ThS. T THANH DUNG TS. NG TH HONG OANH ThS. TRN TH TUYT HOA

Gio trnh

BNH HC THY SN

T SCH I HC CN TH 2005

i

THNG TIN V TC GI PHM VI V I TNG S DNG

CA GIO TRNH

1. THNG TIN V TC GI

Tc gi 1: H v tn:T Thanh Dung

Sinh nm: 1962

C quan cng tc:

B mn:Sinh hc v bnh hc TS.

Khoa: Thy sn

Trng: i hc Cn Th...

a ch Email lin h: ttdung@ctu.edu.vn

2. PHM VI V I TNG S DNG

Gio trnh c th dng tham kho cho nhng ngnh no: Nui trng thu sn, qun

l ngh c, th y, nng hc v bnh hc thu sn.

C th dng cho cc trng no: Cao ng v i hc.

Cc t kha ( ngh cung cp 10 t kha tra cu): Bnh l; bnh truyn

nhim; bnh khng truyn nhim; thuc, ho cht trong thu sn; phng bnh tng

hp.

Yu cu kin thc trc khi hc mn ny: sinh hc c bn, vi sinh i cng, dinh

dng, cht lng nc, k thut nui Thu sn, dch t hc.

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Bnh ho c thuy sa n

MC LC MC LC ................................................................................................................................ 1 BI M U........................................................................................................................... 6

I. GII THIU MN HC.................................................................................................. 6 II. NI DUNG V NHIM V CA MN HC ............................................................. 6

2.1 Ni Dung..................................................................................................................... 6 2.2 Nhim v..................................................................................................................... 6

III. TNH HNH PHT TRIN CA MN HC BNH HC THY SN .................... 7 PHN I: BNH HC THY SN I CNG .................................................................. 9 CHNG I: KHI NIM C BN V BNH L............................................................... 9

I. KHI NIM V BNH L ............................................................................................. 9 1.1 nh ngha................................................................................................................... 9 1.2 Bnh l ........................................................................................................................ 9

II. NGUYN NHN V IU KIN PHT SINH BNH L......................................... 9 2.1 Nguyn nhn pht sinh bnh l................................................................................... 9 2.2 iu kin pht sinh bnh..................................................................................... 11

III. CC LOI BNH........................................................................................................ 11 3.1. Cn c nguyn nhn gy bnh ................................................................................. 11 3.2 Cn c tnh hnh cm nhim ca bnh chia thnh cc nhm sau:........................ 12 3.3 Cn c vo v tr k sinh cc c quan, cc t chc ngi ta chia bnh c, tm thnh................................................................................................................................ 13 3.4 Cn c vo tnh cht qu trnh ca bnh chia. ..................................................... 13

IV. CC TRIU CHNG BNH L................................................................................ 14 4.1 nh ngha triu chng bnh l ................................................................................ 14 4.2 Qu trnh c bn ca bnh l .................................................................................... 14

V. CC THI K PHT TRIN CA BNH................................................................. 18 5.1 Thi k bnh. ......................................................................................................... 18 5.2 Thi k d pht......................................................................................................... 19 5.3 Thi k thnh vng. ................................................................................................ 19 5.4 Thi k khi bnh (thi k cui bnh) .................................................................... 19 5.5 Thi k phc hi ....................................................................................................... 20

Ta i liu tham kha o .............................................................................................................. 20 CHNG II: KHI NIM C BN V BNH TRUYN NHIM V BNH K SINH21

I. KHI NIM C BN V BNH TRUYN NHIM .................................................. 21 1.1 nh ngha v bnh truyn nhim............................................................................. 21 1.2 Ngun gc v con ng lan truyn ca bnh truyn nhim ng vt thy sn... 21

II. BNH K SINH TRNG ............................................................................................. 25 2.1 nh ngha................................................................................................................. 25 2.2 Ngun gc ca sinh vt sng k sinh........................................................................ 26

Ti liu tham kho .............................................................................................................. 32 CHNG III: MT S THUC V PHNG PHP PHNG TR BNH TRN C TM........................................................................................................................................ 33

A. MT S THUC THNG DNG. .......................................................................... 33 I. Tc ng ca thuc v ha cht....................................................................................... 33

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Bnh ho c thuy sa n

1.1. Tc ng cc b v tc ng hp thu....................................................................... 33 1.2. Tc ng chnh v tc ng ph .............................................................................. 33 1.3. Tc ng trc tip v tc ng gin tip.................................................................. 33 1.4 Tc ng chuyn tr v tc ng cha tr.................................................................. 33 1.5 Tc ng hip ng v tc ng tng k................................................................ 33

II. CC YU T HNG N TC NG CA THUC V HA CHT ............. 34 2.1 Yu t v bn thn vt ch (yu t bn trong):......................................................... 34 2.2 Yu t bn ngoi ................................................................................................. 34 2.3 Nhng hin tng dc l xut hin trong qu trnh tc ng ca thuc: ............... 35

III. NGUYN TC S DNG THUC V HA CHT.............................................. 36 B. THUC V HA CHT THNG DNG TRONG NUI TRNG THY SN . 37 I. THUC V HA CHT X L MI TRNG NC........................................... 37

1.1 Chlorine..................................................................................................................... 37 1.2 BKC .......................................................................................................................... 38 1.3 Chloramin T.............................................................................................................. 39 1.4 Iodine ........................................................................................................................ 40 1.5 EDTA........................................................................................................................ 40 1.6 Thiosulphate natri ..................................................................................................... 40

II. Thuc v ha cht dit k sinh trng......................................................................... 41 2.1 ng Sulfat ............................................................................................................... 41 2.2 Thuc tm.................................................................................................................. 42 2.3 Peroxide .................................................................................................................... 42 2.4 Xanh Methylen.......................................................................................................... 43 2.5 Mui n ..................................................................................................................... 43 2.6 Formalin.................................................................................................................... 44

III. Thuc v ha cht x l y ao. ................................................................................... 44 3.1 Vi............................................................................................................................. 44 3.2 Zeolite ....................................................................................................................... 45 3.3 Dy thuc c ............................................................................................................. 46 3.4 Bnh ht tr ............................................................................................................... 47

IV. Cc loi cung cp dinh dng b sung........................................................................ 47 4.1 Vitamin ..................................................................................................................... 47 4.2 Khong...................................................................................................................... 48 4.3 Probiotic.................................................................................................................... 49

V. Thuc khng sinh ........................................................................................................... 50 5.1 Khi nim chung ....................................................................................................... 50 5.2 Nguyn tc s dng khng sinh an ton hp l ........................................................ 51 5.3 Phn loi khng sinh ................................................................................................ 51 5.4 Hot tnh khng khun ca khng sinh ..................................................................... 52 5.5 Phi hp khng sinh: ................................................................................................ 52 5.6 Cc khng sinh thng dng trong nui thy sn....................................................... 53 5.7 S khng thuc khng sinh v cch hn ch............................................................. 53

VI. Mt s cy thuc thng dng trong thy sn ............................................................. 54 6.1. Ti (Allium Sativum L.) .......................................................................................... 54 6.2. C nh ni (Eclipta alba Hassk).............................................................................. 55 6.3 Cy xoan (Melia azedarach L).................................................................................. 55

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Bnh ho c thuy sa n

6.4 Rau sam (Portula Oleracea L)................................................................................... 56 B. PHNG PHP PHNG TR BNH C, TM. ....................................................... 56 I. Tm quan trng ca cng tc phng tr bnh c, tm...................................................... 56 II. Nguyn tc v bin php tng hp phng tr bnh c. .............................................. 56

2.1 Nguyn tc ................................................................................................................ 56 2.2 Cc bin php tng hp phng tr bnh c........................................................... 56

III. Cc nguyn tc chnh phng bnh trn c, tm ............................................................ 59 3.1 Cc nguyn tc chnh phng bnh trn c, tm ........................................................ 59 3.2 Mt s qui nh v vic s dng thuc khng sinh................................................... 59

IV. Mt s phng php tr bnh c, tm........................................................................... 60 4.1 Tm c....................................................................................................................... 60 4.2 Phun thuc xung ao................................................................................................. 60 4.3 Ch bin thuc vo thc n....................................................................................... 61 4.4 Treo gi thuc. .......................................................................................................... 61 4.5 Tim c...................................................................................................................... 61 4.6 Bm thuc................................................................................................................. 61 4.7 Bi trc tip .............................................................................................................. 62

Ti liu tham kho .............................................................................................................. 62 PHN II. BNH C............................................................................................................... 63 CHNG IV: BNH DO VI KHUN V NM ................................................................ 63

I. Bnh do vi khun............................................................................................................. 63 1.1 Bnh m ............................................................................................................. 63 1.2 Bnh trng da ............................................................................................................ 66 1.3 Bnh m gan trn c tra Pangasianodon hypophthalmus......................................... 68

II. BNH NM K SINH.................................................................................................. 71 2.1 Bnh nm thy mi..................................................................................................... 71 2.2 BNH NM MANG ................................................................................................ 74

III. BNH L LOT. CN GI L HI CHNG DCH BNH L LOT TRN C. (EUS: Epizootic Ulcerative Syndrome).............................................................................. 75 Ti liu tham kho .............................................................................................................. 80

CHNG V: BNH DO NGUYN SINH NG VT (ngnh protozoa) ......................... 82 I. Lp trng roi - Flagellata................................................................................................. 83

1.1. Bnh trng roi trong mu c - Trypanosomosis....................................................... 83 1.2 BNH TRNG ROI - COSTIOSIS ......................................................................... 85 1.3 Bnh trng 8 tin mao - Octomitosis ........................................................................ 87

II. Lp bo t trng - Sporozoa .......................................................................................... 88 2.1. Bnh cu trng - Coccidiosis ................................................................................... 88

III. Lp thch bo t trng - Cnidosporidia ........................................................................ 89 3.1 Bnh bo t trng - Myxoboliosis ............................................................................. 89

IV. Lp tim mao trng - Ciliata ....................................................................................... 91 4.1 Bnh t qun trng - Chilodonellosis........................................................................ 91 4.2 Bnh trng bnh xe - Trichodinosis.......................................................................... 92 4.3 Bnh trng qu da - Ichthyophthyriosis.................................................................. 94 4.4. Bnh do trng loa kn .............................................................................................. 96 4.5. Bnh trng hoa loa kn. ........................................................................................... 97

Ti liu tham kho .............................................................................................................. 99

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Bnh ho c thuy sa n

CHNG VI: BNH DO NGNH GIUN SN K SINH ................................................. 100 A. Ngnh giun dp - Plathelminthes ................................................................................. 100 I. LP SN L N CH - MONOGENEA ................................................................. 100

1.1 bnh sn l 18 mc - Gyrodactylosis ..................................................................... 100 1.2 Bnh sn l 16 mc - Dactylogyrosis ..................................................................... 102 1.3. Bnh sn l song thn Diplozoosis. ....................................................................... 103

II. Lp sn l song ch - Digenea ..................................................................................... 105 2.1 SN L K SINH TRONG MT C - DIPLOSTOMOSIS ................................ 105 2.2 BNH MC C - NEODIPLOSTOMOSIS ........................................................... 106 2.3 BNH SN L MU - SANGUINICOLOSIS ...................................................... 107 2.4 BNH SN L GAN - CLONORCHOSIS............................................................ 108 2.5 SN DY - CESTOIDEA ...................................................................................... 110

B. GIUN T - ANNELIDAE.......................................................................................... 111 C. NGNH GIUN TRN - NEMATHELMINTHES ..................................................... 112 I. GIUN TRN - NEMATODA......................................................................................... 112

1.1 GIUN PHILOMETRA............................................................................................ 112 1.2 GIUN CAPILARIA.................................................................................................. 114

II. GIUN U MC - ACANTHOCEPHALA ................................................................. 115 Ti liu tham kho ............................................................................................................ 117

CHNG VII: BNH DO NGNH GIP XC V CC PHI SINH VT KHC ........ 118 I. BNH DO NGNH GIP XC .................................................................................. 118

1.1 Bnh trng m neo - Lernaeosis ............................................................................. 118 1.3 Bnh rn c Argulosis .......................................................................................... 122

II. BNH DO CC SINH VT KHC ........................................................................... 124 2.1 B go (chm chp)................................................................................................ 124 2.2 Bp cy (Dytiscus) .................................................................................................. 125 2.3 Tiu cu to............................................................................................................. 125 2.4 Rong hnh li (Hydrodictyon reticulatum) ........................................................... 125 2.5 Phi sinh vt.............................................................................................................. 126

Ti liu tham kho ............................................................................................................ 131 CHNG VIII: NHNG KHI NIM VA PHNG PHP C BN NGHIN CU BNH TM.......................................................................................................................... 132

I. Nguyn nhn v iu kin pht sinh bnh tm nui .................................................. 132 1. Vt ch ...................................................................................................................... 132 2. Tc nhn gy bnh .................................................................................................... 132 3. Mi trng ................................................................................................................ 133

II. Phng php thu v bo qun mu chn on bnh tm............................................. 133 1. Thu mu .................................................................................................................... 133 2. Chuyn mu n phng th nghim .......................................................................... 134 3. Bo qun mu ........................................................................................................... 135

III. Phng php pht hin bnh tm nui .................................................................... 135 1. Phi theo di cc thng tin v mi trng v qun l ao nui bao gm: ................. 136 2. Quan st du hiu bnh bn ngoi c th tm .......................................................... 136

IV. Phng php chn on bnh..................................................................................... 140 1. Nhng phng php c bn trong phng th nghim ............................................... 140 2. Phng php phn lp v nh danh vi khun .......................................................... 141

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Bnh ho c thuy sa n

3. Phng php m hc ................................................................................................ 141 4. Phng php to phn ng chui nh polymerase (PCR)........................................ 142

Ti liu tham kho ............................................................................................................ 143 CHNG IX: BNH VIRUS.............................................................................................. 144

I. Bnh MBV..................................................................................................................... 144 II. Bnh u vng.............................................................................................................. 145 III. Bnh m trng........................................................................................................... 146 Ti liu tham kho ............................................................................................................ 148

CHNG X: BNH VI KHUN....................................................................................... 149 I. Bnh pht sng............................................................................................................... 149 II. Bnh Vibrio .................................................................................................................. 150 III. Bnh m nu, m en ............................................................................................. 150 IV. Bnh vi khun dng si .............................................................................................. 152 Ti liu tham kho ............................................................................................................ 154

CHNG XI: BNH NM, NGUYN SINH NG VT VA BNH DO CC NGUYN NHN KHC..................................................................................................... 155

I. Bnh nm Mycosis ........................................................................................................ 155 II. Bnh do vi sinh vt bm............................................................................................... 155 Ti liu tham kho ............................................................................................................ 157

CHNG XII: BNH DO CC NGUYN NHN KHC............................................... 158 I. Bnh mang (mang en, mang , phng np mang) ..................................................... 158 II. Bnh hoi c................................................................................................................. 159 III. Bnh cong thn ........................................................................................................... 159 IV. Bnh lt xc khng thnh cng .................................................................................. 160 Ti liu tham kho ............................................................................................................ 162

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Bnh ho c thuy sa n

BI M U

I. GII THIU MN HC

Bnh Hc Thy Sn l mn chuyn su ca ngnh thy sn. Mn hc ny ra i trn c s s pht trin ca y hc, t nghin cu k sinh trng ca ngi: sn l, sn dy m k ch trung gian l c. ng thi ngh nui nui thu sn cng ngy cng pht trin cao, nui vi qui m cng nghip ha, tp trung s lng ln c v mt cao th vic phng, tr bnh c cn c gii quyt cp thit. T dn dn mn Bnh Hc Thy Sn ra i. Tuy nhin, Bnh Hc Thy Sn l mn hc mi v pht trin mun so vi cc mn hc khc. Mn hc ny c lin quan cht ch vi cc mn c s chuyn ngnh khc nh vi sinh, thy ha, ng loi, sinh l c ...c bit l mn hc h tr c lc cho k thut nui v sn xut ging.

Khi phong tro nui thy sn cha pht trin, cc i tng nui ch yu l c, do mn hc ch nghin cu trn i tng l c v c tn l mn bnh c hc Ichthyopathology hoc Fish pathology. Sau thp k 70 tr li y phong tro nui thy sn pht trin, nhiu i tng c nui vi hnh thc nui rt a dng (Ao t, lng, b, ng qung....), ngoi i tng nui l c, cc i tng khc c nghin cu nui: tm, cua, nhuyn th... Cho nn mn hc phi nghin cu cc bnh ca nhiu loi ng vt thy sn khc nn tn gi ca mn hc c m rng hn v c tn l Pathology of Aquatic Animal.

II. NI DUNG V NHIM V CA MN HC

2.1 Ni Dung

Trong phn l thuyt, sinh vin c gii thiu nhng kin thc c bn v bnh hc thy sn. Ni dung bao gm nhng khi nim c bn v bnh l ca ng vt thy sn. Khi nim c bn v bnh truyn nhim v k sinh trng. ng thi, gii thiu cho sinh vin phng php tng hp phng v tr bnh ng vt thy sn, phng php chn on bnh trn ng vt thu sn cng nh cp nht cc thng tin v thuc v ha cht thng s dng trong nui trng thy sn. Phm vi nghin cu bnh cc bnh trn c, tm bao gm: cc bnh do siu vi khun, vi khun, nm, k sinh trng, gip xc v cc sinh vt hi c, tm.

2.2 Nhim v

Mn bnh hc ng vt thy sn c nhim v cung cp cho hc vin nhng kin thc ton din v c bn v bnh hc, cc yu t lin quan n bc pht bnh, phng php chn on bnh, phng php phng tr bnh tng hp, nhng bnh thng gp v gy nguy him cho ngh nui trng thy sn.

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Bnh ho c thuy sa n

III. TNH HNH PHT TRIN CA MN HC BNH HC THY SN

T lu cc nh khoa hc m t mt s bnh c nh: cui th k XIX mt s tc gi xut bn cun sch hng dn bnh c nhng c bn vn m t triu chng lm sng l ch yu. Sang u th k XX cc nh khoa hc th gii bt u nghin cu v vit sch hng dn cc bnh c. Nm 1904, Bruno Hofer ngi c vit cun sch " Tc nhn gy bnh c" (Father of Fish Pathology). Vin s V. A. Dogiel (1882 -1955) thuc Vin hn lm khoa hc lin X c l ngi c cng ln ng gp nghin cu khu h k sinh trng c. ng vit phng php nghin cu k sinh trng c (1929); Bnh vi khun ca c (Bacterial Diseases of Fish, 1939). Theo ti liu ca G. Post vi khun gy bnh c c pht hin u tin vo nm 1894.

Nhng nm 1930 bnh truyn nhim ca c c nhiu nghin cu trong cc phng th nghim. Nm 1949 cun sch gio khoa v bnh c hc c xut bn u tin Lin X c ch bin l tc gi E.M. Lyaiman. Tip theo l cc thp k 50 v 60 cc tc gi chuyn nghin cu v bnh c c tip tc pht trin cc nc: Bychowsky, Bauer, Mysselius- Lin X c, Schaperclau- c, Yamaguti- Nht, Hoffman- M.

Phong tro nui trng thy sn trn th gii ngy cng pht trin mnh m nht l ngh nui tm cc nc Chu - Thi Bnh Dng vo nhng nm ca thp k 80 th lch s bnh tm gn lin vi phong tro nui tm. Nhiu cng trnh nghin cu v bnh tm ng quan tm nh: Couch (1978), Ruangpan (1987), Lightner (1983, 1985), Provenzano (1983), Baticados (1988), Sindermann and Lightner (1988), Johnson (1989), Lightner v Redman (1991) and Bell (1991). c bit, nm 1988 nh bnh hc Sindermann v Lightner pht hin hn 30 loi bnh v triu chng bnh l ca tm bin, cng vi cc nguyn nhn bnh do bnh truyn nhim v khng truyn nhim. Hu ht cc tc nhn gy bnh trn tm bin l do virus, vi khun, nm v nguyn sinh ng vt.

Kt qu nghin cu cc tc nhn gy bnh cho ng vt thy sn n nay rt phong ph: bnh virus ca c n nay phn loi hn 60 loi virus thuc 5 h c cu trc ADN hoc ARN. Bnh virus nhuyn th c 12 loi thuc 8 h, bnh virus gip xc c 14 loi tm v 3 loi cua thuc 5 h. Trong h Baculoviridae gp nhiu nht l bnh Baculovirus.

Vi khun gy bnh ng vt thy sn phn lp c vi trm loi vi khun gy bnh thuc 9 h, vi khun in hnh l nhm vi khun Aeromonas sp, Pseudomonas sp gy bnh nc ngt v nhm Vibrio sp gy bnh nc mn.

Nm gy bnh nc ngt: Saprolegnia, Achlya, Aphanomyces; nc mn: Lagenidium sp, Fusarium, Halipthoros sp va Sirolpidium.

K sinh trng ca ng vt thy sn n nay chng ta phn loi c s lng rt ln v phong ph. Ch tnh k sinh trng c nc ngt thuc khu vc Lin X c phn loi hn 2000 loi (V.A. Dogiel, 1984 - 1985).

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Bnh ho c thuy sa n

B mn bnh c c hnh thnh t u nm 1960 thuc trm nghin cu c nc ngt nh Bng. n nay nc ta hnh thnh b mn bnh c 3 vin I, II, III v c phng chn on bnh c tm i din cho 3 min Bc, Trung, Nam v ven bin. mt s trng i hc c cn b ging dy v nghin cu bnh c tm: Trng a hc Thy Sn Nha Trang, Trng i hc Nng Lm (Th c), Trng i hc Cn Th...

Nhng nm gn y, ngnh nui trng thu sn nc ta pht trin mnh ng k theo hng cng nghip ho ngy cng cao. p ng s pht trin nui trng thu sn bn vng, nc ta c nhiu c s nghin cu bnh c, tm, hnh thnh nhiu phng th nghim bnh hc thy sn vi trang thit b phc v tt cng tc ging dy, nghin cu v chn on bnh cc ng vt thy sn, nhng kt qu nghin cu c b sung dn vo mn hc st vi thc t hn v ngy cng hon chnh v phong ph hn.

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Bnh ho c thuy sa n

PHN I: BNH HC THY SN I CNG

CHNG I: KHI NIM C BN V BNH L

I. KHI NIM V BNH L

Di tc dng ca nhng kch thch bn ngoi, c th sinh vt lun lun bin i thch ng vi nhng thay i . S bin i ca c th sinh vt cn tri qua mt thi gian di. Tuy nhin, nu iu kin mi trng thay i qu t ngt, vt xa phm vi thch ng ca c th, lc ny kh nng thch nghi ca sinh vt vi mi trng s gim v c th biu hin triu chng bnh l. Lc c th hot ng khng bnh thng, cc chc nng sinh l b ri lon, s cn bng gia c th v mi trng b mt i.

1.1 nh ngha

Bnh l g? C nhiu nh ngha khc nhau v bnh, ty theo tc gi khi cp nhng vn khc nhau s c nhng thut ng ring din t. Theo ng Brown, E.E. and Gratzek, J.B., 1980 cho rng Bnh l biu hin trng thi bt thng ca c th sinh vt vi s bin i xu ca mi trng xung quanh, c th no thch ng th tn ti v ngc li khng thch ng th mc bnh v cht. Theo Vin Nghin Cu Sc Kho Thu ng Vt (AAHRI), Thi lan 1995. Trong ti liu Qun l sc kho tm trong ao nui c nh ngha nh sau: Bt k mt s bt thng no trong cu to v chc nng ca c th sinh vt c gi l bnh. C ngha l bnh ch pht sinh do s ly nhim mm bnh m cn do cc vn v mi trng v dinh dng gy ra.

1.2 Bnh l

Bnh l chnh l nhng phn ng ca c th bng s thay i mt phn hay ton b chc nng sinh l bnh thng ca c th sinh vt, khi c tc nhn gy bnh xm nhp, ng thi c s thay i t ngt ca cc yu t ngoi cnh.

II. NGUYN NHN V IU KIN PHT SINH BNH L

2.1 Nguyn nhn pht sinh bnh l

Trong nhng nm gn y ngnh thy sn pht trin rt nhanh. Mc ch ca ngi nui l thu c hiu qu cao nht. Tuy nhin, nh mt qui lut t nhin khi cc hot ng nui pht trin th dch bnh s tng ln. Trong qu trnh nui, cc yu t nh mt nui cao, thc n ngho dinh dng, cht lng nc xu, nhit nc khng thch hp v qun l khng tt l nhng yu t lm cho c, tm yu i, mm bnh c c hi tn cng v ly lan nhanh chng v gy thit hi ln.

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Bnh ho c thuy sa n

Nguyn nhn: l nhng yu t kch thch, tc ng vo c th lm sinh vt thay i hot ng sinh l bnh thng v lm sinh vt b bnh. Bt c mt bnh no cng c nguyn nhn. Nguyn nhn khng ch do cc sinh vt gy bnh m c th mi trng hoc bn thn sinh vt.

Snieszko 1974 gii thch mi quan h gia: mi trng, mm bnh v k ch, qua 3 vng trn theo hnh 1. Bnh xy ra l kt qu tc ng ca 3 yu t trn. Bnh xy ra khi s cn bng ca 3 yu t trn b ph v.

Bnh

Vt ch

Mm bnh Mi trng

Hnh 1.1 Mi quan h gia cc yu t gy bnh.

Khi hi 3 yu t: Mi trng, mm bnh v vt ch th c, tm c th mc bnh. Nu thiu 1 trong 3 yu t th vt nui (c, tm) khng mc bnh. Tuy c, tm c mang mm bnh nhng mi trng thun li cho vt nui v bn thn vt nui c sc khng vi mm bnh th bnh khng th pht sinh c. Do d ngn chn mm bnh bc pht th ngi nui lm tt cc khu sau: Ci to ao tt, ty trng ao h dit mm bnh, chn con ging khe mnh, sch bnh, cung cp thc n y v cht v lng.

Nh vy, 3 yu t trn c mi lin quan mt thit vi nhau, do d khi xem xt nguyn nhn gy bnh cho tm c, khng nn kim tra mt yu t n c m cn phi xem xt c 3 yu t: mi trng, mm bnh v vt nui.

Trong nui trng thu sn, phn ln nguyn nhn gy bnh u tin l nhng bin i xu v mi trng gy sc hay gy tn thng n c th dn n lm gim i kh nng khng bnh ca vt nui.

2.1.1 Tc ng kch thch gy bnh cho c th sinh vt.

C th sinh vt sng trong mi trng chu tc nhiu yu t kch thch nh: Tc nhn l hc, tc nhn ho hc, tc nhn sinh hc do mm bnh nh: virus, vi khun, nm, nguyn sinh ng vt. Sinh vt gy bnh tc ng n vt nui di nhiu hnh

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Bnh ho c thuy sa n

thc nh k sinh cc t bo, t chc c quan gy bnh cho vt nui. Yu t mm bnh ny c th tc ng trc tip hoc gin tip n mi trng sng. T c th nh hng n hot ng sinh l bnh thng ca vt nui.

2.1.2 Do thiu cc cht c th vt ch cn.

Trong qu trnh sng, c th v mi trng c s lin h mt thit, c tc dng qua li, cc cht c th cn khng c hoc khng lm cho c th bin i v mt sinh hc, thm ch c th cht nh bnh thiu dinh dng.

Cn c vo mc c th chia lm 2 loi:

Do khng c hoc thiu cc cht rt cn duy tr c th sng, c th c, tm s c s bin i rt nhanh thm ch c th lm cho c, tm cht t ngt nh oxy, nc

Do thiu mt s cht hoc iu kin sng lc u ca c th sinh vt cha c bin i r nhng c ko di lin tc th s lm cho qu trnh trao i cht b tr ngi, hot ng ca cc h men b ri lon c th khng pht sinh c v pht sinh ra bnh nh thiu cht am, m, ng, vitamin, cht khong Nu trong thc n ca c, tm thiu Canxi v Photpho s lm cho c tm b bnh ci xng, cong thn, d hnh, mm v, ngoi ra cn nh hng n h men tiu ha.

2.1.3 Do bn thn c th sinh vt c s bin i dn n b bnh.

C mt s cht v mt s yu t kch thch trong iu kin bnh thng l cn thit c th p ng nhu cu c th pht trin bnh thng nhng do c th sinh vt c s thay i hoc mt s t chc c quan c bnh l nn cc yu t tr thnh nguyn nhn gy bnh.

2.2 iu kin pht sinh bnh

C th sinh vt pht sinh ra bnh khng nhng ch do mt nguyn nhn nht nh m cn cn c iu kin thch hp. Nguyn nhn quyt nh qu trnh pht sinh v c tnh pht sinh pht trin ca bnh cn iu kin ch c tc dng lm tng ln hay cn tr cho qu trnh pht sinh pht trin ca bnh. Do , nm vng nguyn nhn v iu kin pht sinh bnh hiu r bn cht ca bnh l rt cn thit c bin php phng nga v x l hp l.

III. CC LOI BNH

3.1. Cn c nguyn nhn gy bnh

Cn c vo cc nguyn nhn gy bnh c th chia lm 2 nhm chnh: bnh truyn nhim v bnh khng truyn nhim.

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Bnh ho c thuy sa n

Bnh truyn nhim: l bnh gy ra do tc nhn thuc gii thc vt bao gm: vi khun, virus, nm, nguyn sinh ng vt... Tnh cht ly truyn mnh m v c th thnh nhng dch ln. Ch bnh truyn nhim d nhm ln vi s nhim c cht ha hc.

Bnh khng truyn nhim: l bnh gy ra do mi trng, dinh dng, c t .... Bnh ny khng c tnh lan truyn.

Cc bnh truyn nhim do: - K sinh trng - Vi khun - Nm - Vi-rt

Cc bnh khng truyn nhim do: - Mi trng - Dinh dng - c t

BNH TRONG NUI TRNG THU SN

3.2 Cn c tnh hnh cm nhim ca bnh chia thnh cc nhm sau:

Cm nhim n thun: c, tm b bnh do mt s ging, loi sinh vt gy bnh n c xm nhp vo c th gy ra.

Cm nhim hn hp: C tm b bnh do cng mt lc ng thi 2 hoc nhiu ging loi sinh vt xm nhp vo c th gy ra.

Cm nhim u tin: Sinh vt gy bnh xm nhp vo c th c, tm khe mnh lm pht sinh ra bnh.

Cm nhim k tip: c tm b cm nhim bnh trn c s c cm nhim u tin nh c b nhim nm thy m sau khi c th c b thng.

Cm nhim ti pht: c, tm b bnh khi nhng khng min dch, ln th 2 sinh vt gy bnh xm nhp vo lm cho c pht sinh ra bnh.

Cm nhim lp li: c th c, tm b bnh khi nhng nguyn nhn gy bnh vn cn, tm thi trng thi cn bng gia k ch v vt k sinh nu c sinh vt gy bnh cng chng loi xm nhp vo hoc sc khng ca c th yu s cm nhim

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Bnh ho c thuy sa n

3.3 Cn c vo v tr k sinh cc c quan, cc t chc ngi ta chia bnh c, tm thnh

Bnh ngoi da (Ectoparasites): Trn c bao gm cc bnh nh bnh trng ui, bnh nm thy mi, Trichonosis, Chilodonellosis, Criptobiosis, Lernaeosis. Trn tm cng c mt s tc nhn k sinh trn b mt ca v v cc ph b. Do s pht trin ca cc sinh vt pht trin trn b mt c th tm nh cc tim mao trng Zoothamnium, Epistylis, Vorticella, Acineta v cc to dng si nh Lyngbya. Bnh m en trn v tm, bnh n mn cc ph b tm do nhiu loi vi khun cng gy ra.

Bnh mang: Dactylogyrosis, Cryptobiosis, (Sinergasillosis), Trichodinosis, Ichthyophthyriosis. Trn tm, do cc sinh vt gy bn mang tm nh vi khun, nm, tim mao trng, to v cht cn b bm vo mang lm mang tm c mu nu.

Bnh ng rut (Endoparasites): bnh vim rut do vi trng, Eimerriosis, nguyn sinh ng vt, sn l, sn dy, giun trn, giun u mc.

Bnh mu: bnh m , Trypanosomosis, Sanguinicolosis. Bnh mt s c quan khc: no, mt, c, ti mt, xoang bng, gan.

3.4 Cn c vo tnh cht qu trnh ca bnh chia.

Bnh cp tnh: Bnh cp tnh c qu trnh pht trin rt nhanh chng ch trong vng my ngy n 1-2 tun. C th b bnh hot ng sinh l bin i nhanh chng thnh bnh l, c mt s bnh triu chng bnh cha kp xut hin r th sinh vt cht nh bnh nm mang cp tnh ch cn 1-3 ngy c cht, bnh pht sng ca u trng tm khi pht bnh ch cn 1-2 ngy tm cht ht.

Bnh th cp tnh: Qu trnh pht trin ca bnh tng i di t 2-6 tun, triu chng ch yu ca bnh xut hin v pht trin nh bnh nm mang cp tnh, t chc mang b ph hoi, mang b sng l lot, t mang b t.

Bnh mn tnh: Qu trnh pht trin ca bnh ko di c khi hng thng hoc hng nm. Nguyn nhn v iu kin gy bnh tc dng trong thi gian di v khng mnh lit nhng cng khng d dng tiu tr nh bnh nm mang mn tnh ca c gy mt s t bo mang b cht, mang nht nht. Trong thc t ranh gii gia 3 loi bnh ny khng r v gia chng cn c thi k qu v ty iu kin thay i n c th chuyn t dng ny sang dng khc.

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Bnh ho c thuy sa n

IV. CC TRIU CHNG BNH L

4.1 nh ngha triu chng bnh l

Nhiu tc nhn gy bnh khc nhau xm nhp vo mt hay nhiu c th sinh vt. Nhng chng c qu trnh triu chng din bin ging nhau, qu trnh gi l qu trnh triu chng c bn ca bnh l.

4.2 Qu trnh c bn ca bnh l

Khi tc nhn gy bnh xm nhp vo c th gy ri lon s hot ng bnh thng ca cc c quan to ra hin tng ri lon bnh l. Nhiu bnh c cng 1 qu trnh bnh l th gi l qu trnh c bn ca bnh l.

4.2.1. Gy ri lon s hot ng ca h thng tun hon

C th mun duy tr s sng cn c b my tun hon khe mnh. H thng tun hon khng nhng cung cp cht dinh dng cho c th m cn thi cc cht cn b ra ngoi. c bit, trong khi c th bnh h tun hon cn tp trung bch cu v khng th chng li tc nhn gy bnh. Do c th b bnh, h thng tun hon b ri lon, qu trnh trao i cht ca t bo b tr ngi, sc khng s yu v c th dn n c cht.

a. Thiu mu

l hin tng mu ca c th gim hoc s lng hng huyt cu t i so vi bnh thng gy ra hin tng thiu mu, mt c quan hay t chc no ca c th b thiu mu th gi l thiu mu cc b. B phn thiu mu nhit b h thp, mu sc bin nht. T chc b thiu mu lc u th tch nh li nhng v sau do thiu dinh dng sn sinh ra hin tnga phn gii lm cho t chc b ph, th tch tng ln nh bnh nm mang lm cho mang b thiu mu t chc mang mu trng nht, mt s b phn sng phng ln.

Nguyn nhn dn n hin tng thiu mu c th do sinh vt ht mu, do tc mch mu, do b tt ca b my tun hon hoc thnh phn to mu nh:Fe, Ca, P khng . Tc hi ca vit thiu mu con ty thuc vo mc thiu mu, thi gian, tnh mn cm ca t chc. Nu thiu mu nghim trng c th lm cho t bo t chc b cht dn dn, lm t lit ton thn.

b.Chy mu (xut huyt)

Chy mu l hin tng mu chy ra ngoi huyt qun, nu mu chy ra ngoi c th th gi l xut huyt ngoi cn mu tch t li trong th xoang ca c th th gi l xut huyt ni, c th khi xut huyt ni ln xut huyt ngoi.

Chy mu c th do vch mch mu b ph hoi cng c th vch mch mu khng b dp nt nhng do tnh thm thu ca vch mch mu tng ln m mu c th

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Bnh ho c thuy sa n

tng ln m mu c th thng qua c v d rn c Argulus k sinh bm trn mang v da lm chy mu. Cc nguyn nhn gy ra chy mu gm nhiu yu t nh: c hc, vt l, ha hc sinh vt tc dng. Chy mu cp tnh lm mt s lng mu tng i ln hoc cc c quan trng yu b chy mu thng dn n hu qu xu kh tr khi.

c. ng mu

ng mu l hin tng mt s thnh phn ca mu trong tim hay trong mch mu dnh li b ngng kt thnh khi. Nguyn nhn lm ng mu l lc vch mch mu b thay i do b tn thng, vch g gh d lm cho huyt tiu bn lng ng ng thi tng t bo thng b ni mch mu b tn thng c kh nng sn sinh ra cc si keo lm cho huyt bn dnh li, sau s nhanh chng phn gii to ra nhiu men ln men lin kt cng vi Ca trong mu lm cho Thrombinnogen bin thnh Thrombin.

Mu chy chm to iu kin v thi gian cho mu va ng dnh trn vch mch mu th Fibringen chun thnh Fibrin bn vng lm cho mu ngng kt. Mu chy chm hoc ngng kt, huyt tiu bn c iu kin tch ra 2 bn vch mch mu v tip n vi mng trong ca mch mu lm tng kh nng dnh kt v lng ng, mu chy chm cn gip cho mn ngng kt v cc nhn t ngng kt mu hot ng d dng hn.

d. Tc mch mu

L hin tng mu khng chy c n cc t chc c quan. Nguyn nhn c th do 1 tc ng tn thng, git m xm nhp vo c mch mu di chuyn theo mu gy tc mch mu. Hoc cng c th do vch mch b tn thng gii phng Protrombokinaza l yu t gy ng mu. Do sinh vt, u trng trng, trng trng thnh k sinh lm tc mch mu nh sn l song ch Sanguinicola sp. Ngoi ra cng c th do bt kh hoc do u bu.

4.2.2 Hot t cc b

Hot t cc b l mt b phn no ca c th do cung cp mu b nh tr lm cho t chc b hoi t. Nguyn nhn thng gp l do xoang ng mch b tc, ngoi ra cn c th do s nn bn ngoi ng mch. Bt k ng mch no b tc khng ch l do nhn t c hc lm cn tr mu chy m ng thi h thng thn kinh b kch thch mnh lm cho mch mu b co git lin tc cng dn n hoi t b phn.

a. Ph v tch nc

Dch th c tch t trong cc khe ca cc t chc vi s lng nhiu th gi l ph, cn dch th tch t trong xoang th gi l dch tch nc. Trong dch th ny th hm lng albumin gim, trong c th hay ra ngoi c th u khng lin kt,

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Bnh ho c thuy sa n

dch trong c mu xanh vng. Th tch cc c quan t chc b ph tng ln b mt bng long xanh xao, c nng hot ng ca cc c quan b gim st.

Nguyn nhn dn n cc c quan b ph v tch nc rt nhiu: C th t chc b chn p, do tc ng c gii, c th sinh vt b i hoc thnh phn dinh dng trong khu phn thc n thiu, gan b s cng, thn b yu, h thng thn kinh b ri lon hoc do k sinh trng xm nhp vo c th.

Nhn chung cc t chc c quan b ph v tch nc sau khi tiu tr c nguyn nhn gy bnh c th hon ton hi phc. Nu thi gian qu di, cc t chc c quan b ph v tch nc c nhng bin i qu ln nn mc d nguyn nhn gy bnh tiu tr nhng hin tng ph v tch nc vn cn lm cho t chc b vim, chc nng hot ng ca t chc vn b ri lon, mt s c quan trng nh no chng hn b ph v tch nc d dng lm cho c quan k ch b t vong.

4.2.3 Trao i cht b ri lon

Bt k mt t chc no lc ngh cng nh lc hot ng u thc hin qu trnh trao i cht. Lc c th hot ng mnh, qu trnh trao i cht tng ln v ngc li lc ngh ngi qu trnh trao i cht gim xung. Qu trnh trao i cht chu s iu tit ca h thn kinh trung ng. Trong qu trnh cc cht tham gia trao i c lin quan mt thit vi nhau. Lc c th b bnh s hot ng trao i cht v s lng v cht lng u bin i. tin li nn tch ring tho lun tng phn trong qu trnh trao i cht b ri lon nh hng n s bin i ca t bo, t chc ( ni dung 4.2.5).

4.2.4 Lm cho t chc teo nh li

Qu trnh trao i cht b ri lon lm cho th tch ca t chc c quan ca c th b nh li th gi l t chc b teo c. T chc, c quan teo nh c th do th tch t bo nh li hoc s lng t bo gim, hai qu trnh ng thi pht sinh hoc xy ra trc sau. T chc c quan teo nh khng phi tt c u b bnh ch khi no qu trnh trao i cht b ri lon c th mi mc bnh.

Nguyn nhn lm cho t chc b teo nh:

- Do h thng thn kinh b bnh lm cho qu trnh trao i cht b ri lon.

- Do b chn p, nn lu ngy lm cho h thng tun hon b ri lon.

- S hot ng ca mt s tuyn ni tit mt kh nng iu tit.

- Tc dng ho hc hay vt l cng lm cho c quan c quan teo nh li nh cht phng x.

- Mt s c quan sau mt thi gian di khng hot ng c th b teo nh.

- Ton b c th sinh vt teo nh c khi do b i hoc do h thng tiu ha b tc, c th thiu dinh dng dn n c th gy g, ni tng teo li. Teo

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Bnh ho c thuy sa n

nh biu hin trc tin l t chc m n m, c tim, l lch, gan sau cng l no.

4.2.5 Bin i v s lng v cht lng t bo, t chc

Qu trnh trao i cht b ri lon lm cho s lng v cht lng t bo v cc cht m ca t bo thay i so vi bnh thng gi l bin i tnh cht. C mt s dng bin i di y:

a. T bo, t chc c quan sng ty

Thng do bnh truyn nhim cp tnh, trng c, thiu oxi ton thn dn n lm cho t bo t chc sng ty. Lc ny t bo tin hnh thy phn ng thi c s bin i ion, hm lng ion K+ trong t bo gim, hm lng Na+ v hp cht Clorua tng. S thay i gia cc thnh phn ion l do t bo b tn thng khng nng lng hot ng.

b. Bin i nc

Trong dch tng v hch t bo c nhiu khng bo, loi khng bo ny khng cha m, ng n v nim dch hoc ch c rt t protein lng ng, s xut hin ca khng bo lm t bo tch nc.

S bin i nc v sng ty ca t bo c quan h mt thit vi nhau n lm cho t bo tn thng nhanh lc ion K+ trong mu gim. Trong t bo th ion K+ ra ngoi t bo cn ion Na+ ca dch t bo vo trong t bo. Lc c th b chong (sc ) t bo thiu oxi, nng lng t bo sn ra khng lm yu kh nng dn ion Na+ nn ion Na+ i vo t bo m ion K+ ra ngoi t bo, di cc tnh hung u lm cho ion Na+ trong t bo tng nhiu ln dn n t bo trng nc tc l bin i nc.

c. Bin i trong sut

Bin i trong sut l ch dch t bo hoc cht m ca t bo xut hin cc cht ng u trong nh thy tinh. Cc cht ny nhum bng dung dch Eosin bt mu ng u, ngi ta gi t bo bin i dng trong sut thy tinh. S bin i ny thng xy ra trong t bo t chc m, t bo t chc mu.

d. M bin i

Trong dch t bo xut hin cc git m, ngoi ra lng m vt qu phm vi bnh thng hoc bn thn t bo khng c git m nhng trong dch tng t bo c xut hin git m th ngi ta gi t bo t chc bin m. C quan bin m nghim trng lm cho th tch tng, m khng rn chc mu vng khng bnh thng. M bin i thng l bnh do qu trnh oxy ha cc cht hu c khng m bo; do nguyn nhn thiu mu gy ra, ngoi ra c th c mt s cht c, do c t vi khun lm cho t bo t chc bin i m.

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Bnh ho c thuy sa n

e. Trao i khong b ri lon

Cc cht khong nh Ca, Fe, K, Mg, Na. iu l cc cht dinh dng quan trng ca ng vt, qu trnh trao i cht khong b ri lon lm cho hot ng bnh thng ca c, tm tr thnh bnh l. Trao i Ca b ri lon thng gp hn c. Mui Canxi theo thc n vo rut c hp th tri qua mt qu trnh bin i, trong mu v dch th kt hp vi protein. C th trng thi bnh thng Ca tch lu trong xng, rng l ch yu. Hm lng Ca trong c th thng n nh, nu tha bi tit ra mi trng qua rut v thn. Nhng lc thn kinh b mt kh nng iu tit, tuyn ni tit b ri lon hoc b vim thn mn tnh, h xng b bnh th trongb xng sn c hin tng lng ng. Nu Canxi ha trong vch mch mu c th lm cho vch mch mu mt kh nng n hi, lm bin i tnh cht v mch mu d b v.

f. T chc c th sinh vt b vim .

Chng vim l hin tng c th sinh vt phn ng phng v cc b hay ton thn khi c tc dng kch thch t ngoi vo thng qua phn x ca h thng thn kinh. y l qu trnh c bn trong bnh l.

Bt c mt chng vin no ca c th sinh vt n cng khng xy ra cc hin tng n c m n c quan h mt thit gia 3 qu trnh bin i v cht lng, thm thu ra v tng sinh. Cng 3 qu trnh ny thng khng ging nhau, qu trnh bin i v cht chim u th. c, tm qu trnh thm thu ra tng i thp. Triu chng ch yu ca chng vim: t chc c mu , t chc sng, t chc b nng, t chc vng vim b au, c nng ca t chc c quan b thay i.

Kt qu sau cng ca chng vim trn t chc ca c th sinh vt: Tuyt i b phn chng vim ca c th sinh vt kt thc tt nht l vim cp tnh, sau mt thi gian ngn c th thong qua hp th, ti sinh lin li v c nng ca c th hon ton phc hi.

V. CC THI K PHT TRIN CA BNH.

Di tc dng ca cc yu t gy bnh, c th sinh vt khng phi lp tc b bnh m tri qua mt qu trnh. Cn c vo c trng pht trin tng giai an ca bnh m chia thnh cc thi k sau:

5.1 Thi k bnh.

L thi k t khi nguyn nhn gy bnh xm nhp vo c th n ln th nht xut hin triu chng bnh, lc ny hot ng sinh l bnh thng ca c bt u thay i. Thi k ny di hay ngn khng ging nhau (c th ch my pht nh hin tng trng c, c th vi ngy nh cc bnh truyn nhim, hoc c th vi thng, my nm nh cc bnh k sinh trng). Do n ph thuc vo chng loi, s lng, phng

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Bnh ho c thuy sa n

thc cm nhim ca yu t gy bnh cng nh sc khng ca k ch v iu kin mi trng. C th c, tm b thng khng c thi k bnh.

Thi k bnh chia lm 2 giai on:

- T khi tc nhn gy bnh xm nhp vo c th n khi sinh sn, l nhng bnh do sinh vt k sinh gy ra.

- T khi sinh sn n lc b bnh u tin.

Thi k bnh sinh vt k sinh tm mi cch tch ly cht dinh dng tng cng cng sinh sn v hot ng ca n. V k ch trong thi k ny to ra nhng yu t min dch phng v. Thi k bnh nu c tm c chm sc cho n y , mi trng sng sch s th thi k ny ko di tc hi n tm c hu nh khng ng k. Cn theo di trong qu trnh ng nui c, tm pht hin sm v c bin php phng tr kp thi trong giai on ny l tt nht.

5.2 Thi k d pht.

L thi k chuyn tip t lc xut hin du hiu bnh l u tin n lc bnh l r rng. Thi k ny tc nhn gy bnh tc ng n t chc c quan ca c tm. Vi tc nhn gy bnh l sinh vt thi k ny chng sn sinh rt mnh. Thi k d pht thng ngn, c mt s bnh triu chng khng th hin r nh bnh xut huyt mang.

5.3 Thi k thnh vng.

L thi k bnh pht trin cao nht, triu chng in hnh ca bnh th hin r. Qu trnh trao i cht cng nh hnh thi cu to ca t bo t chc cc c quan trong c th c tm c s bin i. Thi k ny nng nht v thng xuyn gy tc hi cho c, tm. Trong thc t phn chia r rng 3 thi k nh trn rt l kh, bi n chu nhiu yu t nh hng v trong qu trnh tin trin ca bnh thay i phc tp.

V d:

C b nhim Trichodina thi k ny da c nht nht, kh dy, mt nhiu nht v b n.

Trng c b nm thy mi. Hu ht trng c b nhim nm v mt s trng b ung.

5.4 Thi k khi bnh (thi k cui bnh)

thi k ny nu mm bnh thng c th sinh vt th sinh vt c th b cht. Nu thuc cha tr c tc dng dit mm bnh, cc tc nhn gy bnh, triu chng bnh l tuy mt i nhng cha trit , hin tng c cht c gim nhng cha dt hn, cn tng s ln tr.

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Bnh ho c thuy sa n

5.5 Thi k phc hi

Vic cha tr bnh l dt hn, cc chc nng sinh l hon ton phc hi, c th hot ng tr li bnh thng. Cn ch chm sc tt hn bng cch tng khu phn dinh dng cng nh tng khu phn v cht v lng cho c phc hi.

Ta i liu tham kha o

1. Thi Hoa, Bu i Quang T, Nguyn Hu Du ng, 2004. Giao trinh Bnh ho c Thuy san. Nha xu t ban Nng nghip. 423 trang.

2. Ho, N.V., 2000. Mt s vn v k thut nui tm s cng nghip. Nh xut bn nng nghip TPHCM.

3. Kamonporn Tonguthai, S. Chinabut, C. Limsuwan, T. somsiri, P. Chanratchakool, S. Kanchanakhan, I.H. MacRae. Handbook of hybrid catfish: husbandry and health. Aquatic Animal Health Research Institute. 37 pages.

4. Qun l sc khe ao nui tm. Khoa Thy Sn, i hc Cn Th dch. 2002

5. Sindermann C.J. and D.V. Lightner. 1988. Disease Diagnosis and Control in North American Aquaculture. Elservier Scientific Publisher. 431p.

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CHNG II: KHI NIM C BN V BNH TRUYN NHIM V BNH K SINH

I. KHI NIM C BN V BNH TRUYN NHIM

1.1 nh ngha v bnh truyn nhim.

Qu trnh truyn nhim l hin tng tng hp xy ra trong c th sinh vt khi c tc nhn gy bnh xm nhp, tc nhn gy bnh y thuc gii thc vt bao gm: virus, vi khun, nm, k sinh trng.

Trong qu trnh truyn nhim thng bao hm ngha hp hn, n ch s nhim trng ca c th sinh vt, i khi ch l s bt u cm nhim, tc nhn gy bnh ch kch thch ring bit, c trng hp khng c du hiu bnh l r rng. Trong trng hp tc nhn xm nhp vo c th ly bnh nhng cha c du hiu bnh l, lc ny c th gi l qu trnh truyn nhim, song cha th gi l bnh truyn nhim. Bnh truyn nhim l phi km theo du hiu bnh l. Nh vy qu trnh truyn nhim bao gm 3 nhn t:

C tc nhn gy bnh truyn nhim nh: virus, vi khun, nm, k sinh trng.

Sinh vt c mang cc tc nhn gy bnh. iu kin mi trng bn ngoi thun li cho s xm nhp ca cc tc

nhn gy bnh thc y qu trnh truyn nhim. Bnh truyn nhim gy tc hi ln cho k ch do Sinh vt gy bnh c kh nng

sinh sn nhanh nht l virus, vi khun. Ch sau thi gian ngn s lng ca chng tng ln rt nhiu v tc ng lm ri lon hot ng sinh l ca c th k ch. Tc nhn gy bnh cn c kh nng lm thay i, hy hoi t chc m ng thi c th tit ra c t ph hoi t chc ca k ch, lm cho cc t bo t chc hot ng khng bnh thng.

1.2 Ngun gc v con ng lan truyn ca bnh truyn nhim ng vt thy sn

1.2.1 Ngun gc ca bnh truyn nhim ng vt thy sn. Ngun bnh l khu u tin ca qu trnh truyn ly, ngun bnh l ni mm

bnh c tr, sinh si ny n mt cch t nhin v t c bi xut ra ngoi. Trong cc thy vc t nhin: ao, h, sng v cc m, vnh ven bin thng quan st thy ng vt thy sn b mc bnh truyn nhim, ng vt thy sn b nhim bnh l dch t nhin. T mm bnh xm nhp vo cc ngun nc thy sn.

ng vt thy sn b nhim bnh v nhng xc ng vt thy sn b bnh cht l ngun gc chnh gy bnh truyn nhim. Tc nhn gy bnh truyn nhim ng vt

21

Bnh ho c thuy sa n

thy sn sinh sn rt nhanh lm tng s lng v i vo mi trng nc bng nhiu con ng khc nhau ty theo tc nhn gy bnh nh: theo cc vt lot ca c i ra nc qua h thng c quan bi tit, c quan tiu ha, c quan sinh dc hoc qua mang, xoang ming, xoang mi.

Ngoi ra, trong nc c nhiu cht mn b hu c, nc thi cc nh my cng nghip, nc thi ca cc tri chn nui gia cm, gia sc, nc thi sinh hot, phn rc cng to iu kin cho bnh truyn nhim pht sinh, pht trin. * Yu t truyn ly: ng vai tr trung gian a mm bnh t ngun bnh ti vt th cm. Trn yu t ly truyn, mm bnh ch tn ti mt thi gian nht nh ri s b tiu dit, thi gian tn ti ph thuc vo loi mm bnh, loi yu t truyn ly, cc yu t truyn ly gm c nhng yu t hu sinh v nhng yu t v sinh. Cc yu t ly lan c th t: gip xc, nhuyn th, con ngi, t nc, vt dng c, cc ng vt khc, Thc n, sn phm ng vt thy sn v xc cht.

Gip xc, nhuyn thng vt t nhin

Ngoi cnh Ngi v vt nui

Hnh 2.1 ng ly trong ngun dch t nhin

1.2.2 Con ng lan truyn ca bnh truyn nhim ng vt thy sn.

Bng ng tip xc trc tip: ng vt thy sn khe mnh sng chung trong thy vc cng vi ng vt thy sn mc bnh truyn nhim, do tip xc trc tip, tc nhn gy bnh truyn t ng vt thy sn bnh sang cho ng vt thy sn khe.

Do nc:Tc nhn gy bnh truyn nhim trong c th ng vt thy sn b bnh ri vo mi trng nc v sng t do trong nc mt thi gian. Nu ly nc c ngun bnh vo thy vc nui thy sn, tc nhn gy bnh s lan cho ng vt thy sn khe mnh.

Do dng c nh bt v vn chuyn ng vt thy sn: Khi vn chuyn hoc nh bt ng vt thy sn bnh, tc nhn gy bnh c th bm vo dng c, nu dng dng c ny nh bt hoc vn chuyn ng vt thy sn khe th khng nhng n lm ly lan bnh cho ng vt thy sn m cn pht tn ra mi trng nc.

22

Bnh ho c thuy sa n

Mm bnh truyn nhim t y ao: Cng vi cc cht hu c tn ti y ao, tc nhn gy bnh t ng vt thy sn mc bnh truyn nhim, t xc ng vt thy sn cht do b bnh rt xung y ao v tn ti mt thi gian. Nu ao khng c ty dn v phi y k trc khi tin hnh ng nui thy sn, tc nhn gy bnh t y ao i vo nc ri xm nhp gy bnh truyn nhim cho ng vt thy sn.

Do ng vt thy sn di c: ng vt thy sn b bnh di c t vng nc ny sang vng nc khc, tc nhn gy bnh truyn nhim vo vng nc mi, gp lc iu kin mi trng thy i khng thun li cho i sng ca ng vt thy sn, tc nhn gy bnh xm nhp vo c th ng vt thy sn kho lm cho ng vt thy sn mc bnh.

Do chim v cc sinh vt n ng vt thy sn: Chim, c, ri c, ch, mo, bt ng vt thy sn b nhim bnh lm thc n. Tc nhn gy bnh truyn nhim c th bm vo chn m, ming, vo c th ca chng, khi nhng ng vt ny di chuyn ti vng nc khc th tc nhn gy bnh truyn nhim t chng c th i vo nc, ch c hi thun li chng s xm nhp vo c th ng vt thy sn khe vng nc mi v gy bnh truyn nhim.

ng vt thy sn l ngun gc ca mt s bnh truyn nhim cho ngi v ng vt.

C cng nh gip xc, nhuyn th l ngun gc ca mt s bnh truyn nhim cho ngi v gia sc.

Trong c th mt s ng vt thy sn c mang vi khun bnh dch t nh: Clostridium botulinum, Salmonella enteritidis, Proteus vulgaris, Vibrio parahaemolyticus Cc loi vi khun ny c th tn ti trong c th mt s loi ng vt thy sn v n c th ri vo nc v gy nhim bn nc. Nguyn nhn ca ngi mc bnh dch t c th do n c sng hoc c nu nng cha chn c mang vi khun gy bnh nn truyn qua cho ngi.

Trong thy sn, ngun bnh v cc yu t lan truyn c th hin qua s sau:

23

Bnh ho c thuy sa n

CA C C 1 M V QUA N LY:- Do n ao- Bao d ng ch t l ng n c- Th c n t t v m c cho nth ch h p- M t nui th p- Ki m tra a n ca& mi tr ng

AO/KHU NG P

A N CAGI NG

1. S du ng gi ng khng b nh2. X ly

CHIM VA NGV T CO VU

B CA

AO CA

NGU N N C C P

KHA CH N TRA I CNG NHN

CA T NHIN

THI T B

Kh tru ng

Ngn c h n

Ngn c h n

Sa t tru ng tay &chn/ u ng

Sa t tru ng tay &chn/ u ng

Du ng n c gi ngkhoan ho c x ly

T y tru ng b ng viho c b t Clorua

Kh tru ng

1.2.3 Ph

Bnhtheo nhn cn g

Ni mm bntr u tivirus MB

ng vt

Ltru

Lphth

Hnh 2.2 Cc phng php ngn chn s xm nhp ca mm bnh n mi trng ng nui c ng thc truyn ly

c truyn ly t c th bnh qua c th khe bng cc yu t truyn ly g quy lut nht nh m Gramasevxki nu ra, nhng quy lut truyn ly i l c ch truyn ly ca Gramasevxki, gm c:

khu tr u tin ca mm bnh trong c th, l ni c iu kin cho h sinh sn, nhn ln v m bo cho chng c bi xut ra ngoi. Ni khu n rt cn thit cho s lu tn ca mm bnh. V d: ni khu tr u tin ca

V l gan ty ca tm s.

thy sn c 4 phng thc truyn ly.

y qua da, v v mang: c nhiu ni khu tr u tin, do c nhiu ng yn ly v c nhiu loi yu t truyn ly.

y theo ng tiu ha: ni khu tr u tin l rut, ng truyn ly l n, yu t truyn ly ch yu ca ng vt l thc n, ngoi ra nc trong y vc.

24

Bnh ho c thuy sa n

Ly theo mu: ni khu tr u tin, mu ca a, gip xc, mu ng vt thy sn, yu t truyn ly l a hoc gip xc ht mu.

Bnh truyn nhim c th ly theo chiu ngang (Gia cc c th vi nhau) hoc ly t th h ny sang th h khc (ly theo chiu ng), bnh c th ly trc tip hay gin tip.

Da vo cc phng thc truyn bnh ny c th phn loi cc bnh truyn nhim ra nhng bin php phng tr thch ng cho tng nhm bnh truyn nhim.

Da/vy

Mang

Ming

II. BNH K SINH TRNG

2.1 nh ngha

K sinh trng l sinh vt k sinh trn sinh vt khc ly cht dinh dng ca sinh vt lm thc n ng thi gy hi cho sinh vt . Qua thc t sn xut c nh nghi khc: H ng k sinh l mi qu hc tp gia 2 c th. Trong mt sinh vt tm y thng xuyn c tr hay trn c th mt sinh vt khc ly t chc c v dch th ca sinh vt y lm thc n cho mnh ng thi gy hi cho sinh vt . Vdng, quan h

ng vgi l k chcn l ni ck sinh trngk sinh. Khosinh trng h

h

i ngha ny lm sng t 3 gy hi.

t sng k sinh gi l k sinh. K ch khng nhng l ng tr tm thi hay vnh cu c v mi quan h qua li giaa hc nghin cu mt cch cc.

2an h p trongin tt i haHnh 2.3 ng xm nhp ca mm bnh vi khun trn c mi quan h: Quan h ch , quan h dinh

trng. Sinh vt b sinh vt khc gy tc hi un cung cp thc n cho k sinh trng m a n. Cc loi biu hin s hot ng ca k sinh trng vi k ch gi l hin tng h thng cc hin tng k sinh gi l k

5

Bnh ho c thuy sa n

2.2 Ngun gc ca sinh vt sng k sinh.

Thng ngun gc ca sinh vt sng k sinh chia lm 2 giai on:

2.2.1 Sinh vt t phng thc sinh sng cng sinh n k sinh.

Cng sinh l 2 sinh vt tm thi hay lu di sng chung vi nhau, c 2 u c li hay 1 sinh vt c li (cng sinh phin li) nhng khng nh hng n sinh vt kia. Hai sinh vt sng cng sinh trong qu trnh tin ha mt bn pht sinh tc hi bn kia, lc ny t cng sinh chuyn qua k sinh.

V d nh amp: Endamoecha histokytica Schaudinn sng trong rut ngi di dng th dinh dng nh ly cc cht cn b tn ti khng gy tc hi cho con ngi lc ny n l cng sinh phin li, nhng lc c th k ch do b bnh t bo t chc thnh rut b tn thng, sc khng yu, amp th dinh dng nh tit ra men ph hoi t bo t chc rut chui vo tng nim mc rut chuyn thnh amp th dinh dng ln c th gy bnh cho ngi. Nh vy t cng sinh amp chuyn thnh k sinh.

2.2.2 Sinh vt t phng thc sng t do chuyn qua k sinh gi n k sinh tht.

T tin ca k sinh trng c th sng t do, trong qu trnh sng do mt c hi ngu nhin, n c th sng trn b mt hay bn trong c th sinh vt khc, dn dn n thch ng vi mi trng sng mi, y c th tha mn c cc iu kin sng, n bt u gy tc hi n sinh vt kia tr thnh sinh sng k sinh. Phng thc sinh sng k sinh ny c hnh thnh thng xuyn do ngu nhin lp i lp li nhiu ln thng qua k sinh gi ri n k sinh tht.

T tin ca sinh vt k sinh tri qua mt qu trnh lu di thch nghi vi hon cnh mi trng mi, v hnh thi cu to v c tnh sinh l, sinh ha ca c th c s bin i ln. Mt s c quan trong qu trnh sinh sng k sinh khng cn thit th thoi ha hoc tiu gim nh c quan cm gic, c quan vn ng Nhng c quan m bo s tn ti ca ni ging v i sng k sinh th pht trin mnh nh c quan bm, c quan sinh dc. Mt s c tnh sinh hc mi c hnh thnh v dn dn n nh, v di truyn cho i sau, qua nhiu th h, cu to c th cng thch nghi vi i sng k sinh.

2.2.3 Phng thc k sinh.

a. Da theo tnh cht k sinh ca k sinh trng chia:

+ K sinh gi: K sinh trng k sinh gi thng thng trong iu kin bnh thng sng t do ch c bit mi sng k sinh v d nh: Haemopis sp sng t do khi tip xc vi ng vt ln chuyn qua sng k sinh.

26

Bnh ho c thuy sa n

+ K sinh tht: K sinh trng trong tng giai an hay trong ton b qu trnh sng ca n u ly dinh dng ca k ch, c th k ch l mi trng sng ca n. Da vo thi gian k sinh c th chia lm hai loi:

- K sinh c tnh cht tm thi: k sinh trng k sinh trn c th k ch thi gian rt ngn, ch lc ly thc n mi k sinh nh a c Piscicola sp ht mu c.

- K sinh mang tnh cht thng xuyn: Mt giai an, nhiu giai an hay c qu trnh sng k sinh trng nht thit phi sng trn k ch, k sinh thng xuyn li chia ra k sinh giai on v k sinh sut i.

+ K sinh giai on: Ch mt giai on nht nh trong qu trnh pht trin k sinh trng sng k sinh. Trong ton b qu trnh sng ca k sinh trng c giai an sng t do, c giai an sng k sinh nh gip xc chn t Sinergasilus giai on u trng sng t do, giai on trng thnh k sinh trn mang ca nhiu loi c.

+ K sinh sut i: Sut qu trnh sng k sinh trng u sng k sinh, n c th k sinh trn mt k ch hoc nhiu k ch, khng c giai on sng t do nn tch khi k ch l n b cht v d nh k sinh trng Trypanosoma k sinh trong rut a c chuyn qua sng trong mu c.

b. Da vo v tr k sinh chia.

+ Ngoi k sinh: K sinh trng k sinh trn b mt c th trong tng giai an hay sut i gi l ngoi k sinh. c k sinh trng k sinh trn da, trn vy, trn mang, hc mi, xoang ming u l ngoi k sinh v d nh cc ging k sinh trng Trichodina, Ichthyyophthirius, Argulus, Lernaea

+ Ni k sinh: L ch k sinh trng k sinh trong cc c quan ni tang, trong t chc trong xoang ca k ch nh: sn l Sanguinicola sp k sinh trong mu c, sn dy Caryophyllaeus sp, giun u mc Acanthocephala k sinh trong rut c.

Ngoi 2 loi k sinh trn cn c hin tng siu k sinh, bn thn k sinh trng c th lm k ch ca k sinh trng khc v d: Sn l n ch Gyrodactylus sp k sinh trn c nhng nguyn sinh ng vt Trichodina sp li k sinh trn sn l n ch Gyrodactylus sp. Nh vy sn l n ch Gyrodactylus l k ch ca Trichodina nhng li l k sinh trng ca c. Tng t nh trng m neo Lernaea sp k sinh trn c, nguyn sinh ng vt Zoothamnium sp k sinh trn m neo Larnaea sp.

2.2.4 Cc loi k ch.

C rt nhiu lai k sinh trng c qu trnh pht trin qua nhiu giai on, mi giai an c c im hnh thi cu to v yu cu iu kin mi trng sng khc nhau nn c s chuyn i k ch. Thng chia lm 2 loi k ch theo hnh thc k sinh ca k sinh trng.

27

Bnh ho c thuy sa n

hiu th no l k ch trung gian v k ch cui cng ta xem v d sau:

V d 1: rut c chp:

Sn l rut Azygiia ( trng ri vo trong nc) n u trng Miracidium Ra khi c SSn.h.tnh Xm nhp vo gan c

At. Cercaria At. Redia Sporocysces

SSn.v tnh

u trng k sinh trong c (c: l k ch trung gian I)

V d 2: Sn l gan k sinh cc ng vt c l k ch cui cng

( trng ri vo trong nc)

Sn l gan Clonorchis SSn.h.tnh N u trng Miracidium

Xm nhp vo gan c

At. Metacercaria At Cercaria At. Redia Sporocyses u trng k sinh trong c (c: l k ch trung gian I); C: l k ch trung gian II

- K ch cui cng: K sinh trng giai on trng thnh hay giai an sinh sn hu tnh k sinh ln k ch th gi l k ch cui cng.

- K ch trung gian: K sinh trng giai oan u trng hay giai on sinh sn v tnh k sinh ln k ch gi l k ch trung gian. Gian on u trng v giai an sinh sn v tnh nu k sinh qua 2 k ch trung gian th k ch u tin l k ch trung gian th nht cn k ch k tip l k ch trung gian th 2.

2.2.5 Phng thc cm nhim ca k sinh trng.

K sinh trng cm nhim ch yu bng 2 con ng:

a. Cm nhim qua ming.

Trng, u trng, bo nang ca k sinh trng theo thc n, theo nc vo rut gy bnh cho c nh: K sinh trng hnh cu Eimeria sp, giun trn Capilaria sp.

b. Cm nhim qua da.

K sinh trng qua da hoc nim mc, c cn qua vy v mang i vo c th gy bnh cho k ch, cm nhim qua da c 2 loi:

- Cm nhim qua da ch ng: u trng ch ng chui qua da hoc nim mc vo trong c th k ch. V d u trng sn l Posthodiplostonum cuticola c thng v chui vo lp di da tip tc pht trin.

28

Bnh ho c thuy sa n

- Cm nhim qua da b ng : K sinh trng thng qua vt mi gii vo c da ca k ch k sinh gy bnh. V d: K sinh trng Trypanosoma sp. Nh a c c thng da ht mu c khi k sinh trng t rut a vo mu c.

2.2.6 Mi quan h gia k sinh trng, k ch v iu kin mi trng.

K sinh trng, k ch v iu kin mi trng c quan h vi nhau rt mt thit. Quan h gia k sinh trng vi k ch ph thuc vo giai oan pht trin, chng loi, s lng k sinh trng, v tr k sinh v tnh trng sinh l ca k ch. iu kin mi trung sng ca k ch nh hng trc tip hoc gin tip n k sinh trng, k ch v mi quan h gia chng.

a. Tc ng ca k sinh trng i vi k ch.

K sinh trng khi k sinh ln k ch gy hu qu mc tuy khc nhau nhng nhn chung lm cho k ch sinh trng chm, pht dc khng tt, sc khng gim c th b cht. C th tm tt nh hng ca k sinh trng i vi k ch nh sau:

b. Tc ng kch thch c hc v gy tn thng t ho t chc

y l tc dng thng thng nht ca k sinh trng i vi k ch nh ban m giun kim b quanh hu mn ngi lm cho ngi c giun kim k sinh nga ngy kh chu.

VD: Rn c Argulus dng ming v gai bng co ln da c kch thch lm cho c kh chu bi li hn lon hoc nhy ln mt nc.

Tc ng nn v lm tc: c mt s k sinh trng k sinh cc c quan bn trong lm cho mt s t chc t bo b teo nh li hoc b t lit ri cht. Loi tc dng ny thng thy t chc gan, thn, tuyn sinh dc nh sn dy Ligula sp. Mt s k sinh trng k sinh chn p mt s c quan quan trng nh tim, no dn n lm cho k ch cht nhanh chng. K sinh trng k sinh s lng ln trong rut c th lm tc rut ca vt ch nh Acanthocephala sp, Boethriocephalus sp

Tc ng ly cht dinh dng ca k ch: Tt c k sinh trng giai on k sinh u cn cht dinh dng t k ch, v vy nn nhiu hay t k ch u b mt cht dinh dng v b gy tn hi cho c th. K sinh trng Lernaea k sinh trn c m, c trm vi s lng ln s lm cho gy thng thy u rt to, bng v ui tht li nu khng x l vt ch s cht.

Tc ng gy c vi k ch: K sinh trng trong qu trnh k sinh tin hnh trao i cht, bi tit cht cn b ln c th k ch ng thi k sinh trng tit ra cht c gy c cho k ch. Qua nhiu kt qu nghin cu cho bit rn c Argulus c kh nng tit ra dch ph hoi t chc da v mang c. a c ht

29

Bnh ho c thuy sa n

mu c tit ra mem chng ng mu, k sinh trng Trypanosoma sp c men lm v t bo hng cu.

Lm mi gii gy bnh: Nhng sinh vt k sinh ht mu thng lm mi gii cho mt s k sinh trng khc xm nhp vo c th k ch v d: a c ht mu c thng mang mt s k sinh trng ly cho c khe mnh.

Tc dng ca k ch i vi k sinh trng: Vn tc dng ca k ch i vi k sinh trng rt phc tp, i vi ng vt thy sn nghin cu v vn ny cha nhiu nn s nh hng tht c th kh c th kt lun chnh xc.

c. Phn ng ca t bo t chc k ch

K sinh trng xm nhp vo c th k ch gy kch thch lm cho t bo t chc c phn ng. Biu hin ni k sinh trng i vo t chc m hnh thnh bo nang hoc t chc xung quanh v tr k sinh c hin tng t bo tng sinh, vim lot hn ch sinh trng v pht trin ca k sinh trng, mt khc lm cho v tr bm ca k sinh trng khng cn vng chc.

v d : K sinh trng qu da Ichthyophthirius k sinh trn da c, da ca k ch nhn kch thch, t bo thng b tng sinh bao vy k sinh trng thnh cc bc trng lm tm nn cn gi l bnh. Sn l Posthodiplostonrum cuticola k sinh trn da v c c hnh thnh bo nang, vch c t bo sc t en bao vy nn da c c cc ht lm tm en.

d. Phn ng ca dich th.

K sinh trng xm nhp vo th k ch sn sinh ra phn ng dch th. Phn ng dch th c nhiu dng nh: pht vim, thm thu dch pha long cc cht c, va tng kh nng thc bo lm sch cc d vt v cc t bo cht ca bnh. Nhng phn ng dch th ch yu l sn sinh ra khng th, hnh thnh phn ng min dch.

e. Tui ca k ch nh hng n k sinh trng.

Thng k ch trong qu trnh pht trin th c th tng trng, k sinh trng k sinh trn c th k ch cng c s thay i cho thch hp. i vi k sinh trng chu k pht trin c k ch trung gian thng xy ra hai hng:

Mt s ging loi k sinh trn c th k ch c cng v t l cm nhim gim i theo s tng ln ca tui k ch v d sn dy Bothriocephalus gowkongensis

Mt s k sinh trng k sinh c cng v t l nhim k sinh tng ln theo tui ca k ch do lng thc n tng lm trong thc n k ch trung gian cng tng theo, thi gian cng di kh nng tch t v c hi nhim bnh cng

30

Bnh ho c thuy sa n

nhiu. V vy c ln thng c cng v t l cm nhim k sinh trng cng cao.

Mt s k sinh trng pht trin khng qua k ch trung gian t c lin quan n tui ca k ch nh: Chilodonella sp, Trichodina nobilis k sinh trn c cc giai on. Tuy nhin giai on c bt, c hng ging nu nui mt dy, c th cn non nn thng c cng v t l cm nhim cao v gy thit hi ln cho sn xut.

f. Tnh n ca k ch nh hng n k sinh trng.

Tr s k sinh trng l ngoi k sinh v loi k sinh trng chui trc tip qua da vo k sinh bn trong c th k ch ra cn li k sinh trng l ni k sinh chu tc ng rt ln n chui thc n ca c.

C hin n mn b hu c, thc vt thy sinh, ng vt nh nn hay cm nhim k sinh trng c chu k pht trin trc tip hay giun sn c chu k pht trin qua 1 k ch trung gian l ng vt ph du.

V d: c hin hay cm nhim k sinh trng l thch bo t trng Cnidosporidia, c trm c thng cm nhim k sinh trng Balantinidium.

Ngc li c d n cc ng vt thy sinh ln v n c thng b cm nhim cc loi k sinh trng c chu k pht trin phc tp. Giai on u trng ca k sinh trng k sinh cc loi k ch l con mi ca c d nh c nheo, c thiu hay cm nhim sn l song ch Isoparorchis sp c tr, c vc thng cm nhim sn l song ch Dollfustrema sp.

C n sinh vt y b cm nhim cc loi giun sn m qu trnh pht trin ca chng c qua k ch trung gian l nhuyn th, u trng cn trng nh c chp thng b cm nhim sn dy Caryophyllacreus.

g. Tnh trng sc khe ca k ch tc ng n k sinh trng.

ng vt khe mnh sc khng tng khng d dng b cm nhim k sinh trng, ngc li ng vt gy yu sc khng gim, k sinh trng d dng xm nhp vo.

V d: trong cc ao nui c nu nui mt cao, thc n thiu, mi trng nc bn c chm ln d dng nhim bnh hn.

2.2.7 Tc dng ca iu kin mi trng i vi k sinh trng.

K sinh trng sng k sinh trn c th k ch nn n chu tc ng bi mi trng th nht l k ch ng thi mi trng k ch sng hoc trc tip hoc gin tip c nh hng n k sinh trng.

a. mn ca thy vc nh hng n k sinh trng.

31

Bnh ho c thuy sa n

mn trong cc thy vc nh hng n h sinh thi ca c v khu h k ch trung gian, k ch cui cng ca k sinh trng. Gia cc ging loi c s mm cm gia k sinh trng c khc nhau nn khi khu h c thay i nh hng n khu h k sinh trng. mui cao lm nh hng n s pht trin ca k ch trung gian, k sinh trng c nc ngt.

b. nh hng ca nht nc n k sinh trng .

Nhit nc khng nhng nh hng trc tip n k sinh trng k sinh trn c th ng vt thy sn m cn nh hng n k ch trung gian, k ch cui cng v iu kin mi trng. Mi ging loi k sinh trng c th sng, pht trin nhit thch ng. Nhit qu cao hay qu thp u khng pht trin c.

V d: sn l n ch 16 mc Dactylogyrus vastator nhit 24-26oC sau khi trng thnh 4-5 ngy s thnh thc v trng, 3-4 ngy phi pht trin t l n 80-90%, nhng sn l n ch 16 mc loi Dactylogyrus extensus thich hp nhit 15oC, nu nhit cao t l n ca trng s rt thp

c. c im ca thy vc nh hng n k sinh trng.

Thy vc t nhin, thy vc nui ng vt thy sn do din tch c su, hm lng dinh dng khc nhau nn nh hng n thnh phn s lng v cng cm nhim ca k sinh trng. Trong cc thy vc t nhin s loi k sinh trng phong ph hn trong cc ao nui, do trong cc thy vc t nhin , khu h ng vt l k ch trung gian, k ch cui cng cng a dng hn. Trong khi , thy vc ao thng xuyn c ty dn, dit tp, tiu c. Tuy th tm c nui trong ao mt dy i lc c bn phn v cho n nn mi trng nc bn hn lm cho k sinh trng k sinh trn tm, c pht trin thun li v d ly lan. Mt d s lng ging, loi t hn nhng cng v t l cm nhim ca k sinh trng trn tm , c cao hn cc thy vc mt nc ln.

Ti liu tham kho

1. Brown, E. E and J. B Gratzek, 1980. Fish farming handbook. Food, bait, tropical and goldfish.

2. Manual of diagnostic Tests for Aquatic Animals, 2003. http://www.oie.int

3. Nguyn Ln Dng, 2000. Vi sinh hc. Nh xut bn gio dc.

4. Phm, L. , 1992. Vi sinh vt ngun nc, quan h ca chng vi bnh tm c. 5. Qun l sc khe ao nui tm. Khoa Thy Sn, i hc Cn Th dch. 2002

6. Trn Th Thanh Hin, Nguyn Anh Tun, Hunh Th T, 2004. Gio trnh Dinh dng v thc n thu sn.

32

Bnh ho c thuy sa n

CHNG III: MT S THUC V PHNG PHP PHNG TR BNH TRN C TM.

A. MT S THUC THNG DNG.

I. Tc ng ca thuc v ha cht

1.1. Tc ng cc b v tc ng hp thu

Cn c vo s pht huy tc ng ca thuc, thuc lu li b phn bi hay tim hoc hp thu vo trong c th xc nh.

Tc ng cc b: hiu lc ca thuc c pht huy ti ch. V d: Bi cn iod c tc dng ngoi daTc ng cc b khng ch biu hin bn ngoi c th m cn biu hin bn trong c th nh thuc tr bnh ng rut pht huy tc ng trc khi c hp thu vo mu.

Tc ng hp thu: hiu lc ca thuc c pht huy khi thuc c hp thu vo h tun hon.

1.2. Tc ng chnh v tc ng ph

Khi s dng mt loi thuc no c th pht sinh 2 loi tc ng:Tc ng chnh l tc ng ch yu ca thuc khi iu tr mong mun. Tc ng ph l tc ng km theo. Khi s dng thuc cn phng s nguy hi ca tc ng ph. Cc nh bo ch thuc tm mi cch gim ti thiu cc tc dng ph.

1.3. Tc ng trc tip v tc ng gin tip

Tc ng trc tip: ch phn ng ca thuc pht sinh trc tip ti ni thuc tip xc. Tc ng gin tip: ch phn ng ca thuc b phn khc khng do thuc trc tip tc ng.

1.4 Tc ng chuyn tr v tc ng cha tr

Tc ng chuyn tr: tc ng trn cn bnh. Tc ng cha triu chng: ch lm mt hoc gim triu chng bnh, khng c (hoc c rt t) tc ng trn cn bnh.

1.5 Tc ng hip ng v tc ng tng k

Hip ng cng (cng lc b sung hay hip ng b sung): (A+B) = (A) + (B). Hip ng nhn (cng lc bi tng hay hip ng bi tng): (A+B) > (A) + (B). Tng k nhau nu chng lm mt tc ng ca nhau hoc gy thnh cht c. Tng k sinh l: khi phi hp s gy hin tng sinh l tri ngc nhau, lm trit tiu tc ng ca nhau. Tng k ha hc: khi phi hp s xy ra phn ng ha hc lm mt tc ng

33

Bnh ho c thuy sa n

ca nhau hoc hp thnh cht c nguy him. Tng k vt l: khi kt hp 2 cht ngoi c th c s xung khc v vt l lm mt tc dng hoc lm bin dng thuc.

*ng dng ca tc ng tng k trong iu tr v gii c: Trong iu tr, khng dng nhng cht tng k nhau. Trong khi , tc ng gii c th thng dng nhng cht i khng vi cht c gii c. C 3 phng php:

+ Gii c bng phng php vt l: l lm cho cht c khng c hp thu hoc hp thu rt t vo c th, ch khng lm cht c tr thnh khng c.

+ Gii c bng phng php ha hc: l lm cho cht c tr thnh cht khng c bng nhng phn ng ha hc nh kt ta, oxy ha, trung ha.

+ Gii c bng phng php sinh l: l dng nhng cht c tc ng sinh l i khng nhau lm mt tc ng sinh l i khng nhau lm mt tc ng c.

II. CC YU T HNG N TC NG CA THUC V HA CHT

2.1 Yu t v bn thn vt ch (yu t bn trong):

Do loi vt nui: cng mt loi thuc, loi vt ny c th nhy cm hn loi khc.

Do tui vt nui: Vt nui non v gi dng liu nh hn ng vt trng thnh. Vt cn non c tm vc v th trng b hn vt trng thnh, cc c quan cha pht trin hon chnh nn s trao i cht v chuyn ha t chc khc ng vt trng thnh, t tnh cm th i vi thuc v ha cht ca ng vt non khc ng vt trng thnh c v lng ln cht. Vt nui gi c s chuyn ha gii c v thi tr thuc km hn ng vt non.

Tnh cm th ca tng c th. Tnh trng c th: Nhiu loi thuc ch c tc ng mnh khi c th trng

thi bnh, khi c th bnh thng khng c tc ng. Bnh th mn tnh phi dng liu cao hn th cp tnh.

2.2 Yu t bn ngoi

a. Yu t v thuc:

Do tnh cht ca thuc: thuc d phn ly c tc ng nhanh v ngc li (v ho tnh). Thuc th kh tc dng nhanh hn th lng, th rn. thuc tan nhiu hoc bay hi v khuch tn mnh th tc ng nhanh, mnh hn thuc t tan hoc bay hi v khuch tn chm (v l tnh). Do cch tc ng thuc nh vy nn trong tr liu thng dng liu lng t thp n cao.

34

Bnh ho c thuy sa n

Tc ng ca thuc ph thuc rt ln vo cng phn ng ca thuc v c trng c s ca sinh vt.

Ph thuc phng php dng thuc: tim thuc c tc ng nhanh hn trn thuc vo thc n; tim tnh mch c tc ng nhanh hn tim vo c.

Ph thuc nng thuc: trong phm vi nht nh nng thuc tng, tc dng ca thuc cng tng.

Ph thuc nhit v thi gian: khi dng phng php tm hoc ngm c th tc ng ca thuc lin quan n nhit v thi gian.

b. Yu t v mi trng

Nu vt nui b bnh m c sng trong iu kin ngoi cnh thch hp, c chm sc tt tc ng ca thuc cng c pht huy. Kt qu nghin cu thc nghim cho thy hm lng hu c ha tan trong nc cng ln, trong ca nc cng thp th hiu qu ca CuSO4 gim. Nhit , pH, kim, cng, Oxy ho tan cng nh hng n tc dng ca thuc.

2.3 Nhng hin tng dc l xut hin trong qu trnh tc ng ca thuc:

a. Quen thuc

Nhng thuc dng trong thi gian di tc ng ca n yu i v phi dng liu cao hn m khng gy tc ng ng k. V phng din sinh hc, tnh quen thuc l hin tng thch nghi ca t bo i vi mi trng ha hc, do a n suy gim tc dng. Thng xy ra nhng dc phm tc ng trn h thn kinh trung ng.

b. Tnh tch ly

L tnh cht ca mt s thuc t b phn hy trong c th, do nu dng nhiu ln trong mt thi gian c th tch ly thnh liu ng c.

c. Tnh nghin thuc

L tnh quen thuc kt hp vi s n l ca c th i vi tc ng ca thuc.

d. Hng phn Kch thch Kch ng

Hng phn: hin tng tng cng chc nng v hot ng ca cc c quan, cc m, cc t bo, nht l thn kinh ca ton c th. Kch thch: nguyn nhn gy ra hng phn. Kch ng: khi kch thch qu to nn s bin i ni b kch thch gi l kch ng.

e. c ch

L hin tng gim thiu chc nng v hot ng ca cc c quan, cc m, cc t bo, nht l t bo thn kinh.

35

Bnh ho c thuy sa n

III. NGUYN TC S DNG THUC V HA CHT

Do iu kin ca nhng ngi nui c, tm rt khc nhau, ng thi c cu loi c tm th nui ty thuc: h thng hay loi hnh nui, cc thit b dng nui, cht lng nc v a im nui cng khc nhau. Do , phng php p dng trong s dng thuc v ha cht cn phi c iu chnh ph hp. Nhng nhn chung khi x l ha cht phi theo nhng nguyn tc sau:

1. Phi chn on chnh xc nguyn nhn gy bnh trc khi quyt dng x l thuc hay ha cht.

2. c k hng dn s dng thuc trn nhn thuc. Nu cha r cch s dng loi thuc hay ha cht cn dng, phi hi k ngi c chuyn mn.

3. Lu n cc quy nh v s dng thuc ca nh nc.

4. S dng ng liu lng, ng phng php (x l nc, ngm, tm, tim, trn vo thc n,..)

5. Nu mi s dng thuc ln u nn th iu tr vi s lng t trong din tch nh trc khi tin hnh iu tr ton b.

6. Tnh ton ng thi gian ngng thuc hay ha cht.

7. Hn ch ti a vic s dng khng sinh phng bnh.

8. Ghi chp y v chnh xc cc thng tin c c trong qu trnh tr liu.

9. Nn thc v s an ton sc khe, v tc hi i vi mi trng xung quanh v sc khe ngi tiu dng khi s dng thuc v ha cht

10. Xem xt hiu qu kinh t trong vic x l thuc v ha cht. * Mt s lu khi dng ha cht x l mi trng

Ha cht dng x l mi trng c rt nhiu loi, v th cn phi hiu hot tnh ca tng loi v dng ng theo hng dn c hiu qu cao.

Khi dng ha cht x l nc phi bit thi gian chng ht tc dng m bo khi a vo ao nui khng nh hng n tm, c nui.

Dng ha cht x l nc cho ao ang nui tm, hay c phi lu l ha cht s lm cht to v cc vi sinh vt c li trong ao. Thng thng sau khi dng ha cht th mi trng nc c th thay i nh to cht lm nc ao trong, gim quang hp cp oxy cho ao, nn y ao s xu hn do to cht lng xung y ao.

Sau khi dng ha cht nn ci thin mi trng ao nui, nu h nc ao trc khi dng ha cht th cp thm nc mi, cn nu khng h nc th phi thay nc cho ao.

36

Bnh ho c thuy sa n

Dng thuc x l mi trng ao ang nui tm, c phi dng ng liu v dng mt ln, trnh dng liu thp v dng nhiu ln lin tip nhau, v nh th mu nc ao s mt v kh gy mu tr li.

* Nhc im ca vic dng thuc v ha cht

nh hng ti ngun thc n t nhin: ha cht c th dit phn ln to trong h thng nui, gim ng vt ph du v ng vt y.

S dng thng xuyn thuc khng sinh s to ra dng vi khun khng thuc. Thuc hay ha cht c th tn lu trong c th vt nui, nh hng n sc

kho ngi tiu dng.

Tc ng tm l ngi tiu th. B. THUC V HA CHT THNG DNG TRONG NUI TRNG THY SN

Thuc l nhng cht thin nhin hoc tng hp, c kh nng hi phc li nhng chc nng sng vn c ca c th sng. Thuc l nhng sn phm c ngun gc t ng vt, thc vt, khong vt hay sinh hc c bo ch dng cho ngi nhm: phng bnh, cha bnh, phc hi, iu chnh chc nng c th, lm gim triu chng bnh, phc hi hoc nng cao sc khe ca vt nui.

Mc ch s dng thuc v ha cht trong thy sn: Trong nui trng thy sn, thuc v ha cht c dng vi cc mc ch chnh sau:

Ci to ao trc khi nui: ha cht cn c s dng trong trng hp ty ra cc dng c v b cha trong cc tri sn sut ging.

Ci thin mi trng ao nui: lm giu thnh phn phiu sinh ng v thc vt trong nc nhm lm tng lng thc n t nhin cho i tng c nui. Hoc trong trng hp ci to nn y ao hay gi cho cc yu t thy ha khng b bin ng ln.

Kch thch tng trng v tr bnh: bao gm cc loi vitamin, khong vi lng v khng sinh.

Mt s loi ha cht thng dng phng tr bnh c, tm

I. THUC V HA CHT X L MI TRNG NC

1.1 Chlorine

Cng thc:Ca(OCl)2

Tn gi: Chlorin, bt ty trng, chlorua vi, canxi hybochlorite

37

Bnh ho c thuy sa n

Tnh Cht:

Dng bt kh trng hoc dng bt kh mu trng xm c mi Clo, t tan trong nc hoc ru. Trong khng kh bt ty trng ht CO2 v nc, dn dn phn gii v mt tc dng. Di tc dng ca nh sng v nhit, bt ty trng cng c th phn gii. Hm lng Clo c tc dng 25 - 30%.

Tc dng: Chlorine l hp cht oxy ha rt mnh v c tnh c i vi sinh vt. chlorine c kh nng oxi ha hp cht hu c, nitrit, ion st v sulfid. Chlorine tiu dit cc tc nhn gy bnh cho vt nui; vi khun, virus, to, v cc sinh vt khc c trong nc.

Khng th th vt nui vo ao, khi d lng chlorine trong nc ao cha ht di tc dng ca nh sng mt tri c th s dung sodium thiosulfat trung ha. T l trung ha chlorine /sodium thiosulfat = 1/7(Boyd, 1990). Dng thng s dng l Calci Hypochloride hoc Sodium hypochloride (Ca(OCl)2, NaOCl). Khi ha tan chlorine vo nc s hnh thnh Cl2, HOCl, v OCl- v lng ca cc thnh phn ny ty thuc vo pH nc.

Ca(OCl)2 Ca2+ + HOCl + Cl2 + OH- HOCl ' H+ + OCl- Cl2 t khi tn ti pH thp < 2

HOCl tn ti khi 2< pH < 6

HOCl v OCl- cng tn ti khi 6 < pH < 9

OCl- chim u th khi pH >9

Liu lng: Liu lng s dng chlorine rt bin ng, ty thuc vo pH v ph thuc vo mt s yu t khc nh cht hu c ha tan, ammonia Trong nui tm dng ty trng dung c v s l sch mi trng nc ao nui c th dng liu lng l 15-20ppm.

Hin ti c nhiu ni s dng chlorine nh l mt cht dit cc mm bnh v hn ch to pht trin, nng cao cht lng nc trong ao nui, nng s dng trong ao c n 0.1 ppm, trong ao tm c th n 3ppm. Khi dng chlorine s lm gim ng k hm lng phiu sinh thc vt trong ao.

Ch : CaCl(OCl) d phn gii mt tc dng, nn cn gi kn, ni thong, mt v kh. Khi s dng, phi tnh lng thuc c hm lng Clo chnh xc mi c tc dng cha bnh. CaCl(OCl) c th lm phng da, khi s dng cn eo gng tay.

1.2 BKC

Tn gi: Benzalkonium chloride

38

Bnh ho c thuy sa n

Tnh cht: Sn phm thng mi thng cha t 50 - 80% hot cht BKC. BKC dng lng

Tc dng: BKC l cht dit khun ph rng, dit c nm, to v c mt s protozoa. c s dng nh bin php phng v tr liu trong ao tm khi c biu hin xu hay bnh mi bt u. Thng s dng khi thi tit thay i t xut, to trong ao c biu hin tn hay tm c hin tng n yu, biu hin bt thng.

Phng bnh, x l ao: s dng BKC 7-10 ngy 1 ln ty vo cht lng nc. Tr bnh (sng thi ui, mang , t ru, m en nu trn v): liu tng gp i, 2 - 3 ngy/ln

Liu lng: Liu lng s dng t 0.6-1 ppm (50% hot cht) hay 0.3 - 0.6 ppm (80% hot cht) phng bnh.

1.3 Chloramin T

Cng dng:

c s dng tr cc tc nhn gy bnh bn ngoi nh Mycobacteria, khu t trng, trng mt tri, trng qu da v sn l n ch.

Cng nh nhng ha cht khc, nn s dng liu thp sau s tng dn liu lng ln trong trng hp cn thit. Phng php ny c u im l tn t chi ph v thng hiu qu hn dng liu cao. S dng liu thp thng t gy sc cho c v khng cn phi ngng thc n trong qu trnh tr liu.

C th dng trong qu trnh iu tr bnh bng BKC, v chloramin T c ph dit trng rng hn BKC nhng khng c kh nng ty mnh nh BKC. Tuy nhin khng c dng hai cht ny trong cng mt lc.

Liu dng:

Thng thng hn ch tc hi i vi c nn s dng nng 0,5 - 2 ppm sau tng t t nu cn thit.

Tuy nhin liu dng ca ha cht ny ty thuc vo cng ca nc v pH. Nu nc c cng thp v pH

Bnh ho c thuy sa n

Khng dng chloramin T nng cao bng phng php nhng, bi v cht ny s gy hi t chc mang ca ng vt thy sn.

C th s dng chloramin B trong trng hp khng c chloramin T, tuy nhin c th tng liu s dng ln v hot tnh ca chloramin B thp hn chloramin T

1.4 Iodine

Tn gi: I-od

Tc dng: y l sn phm gc iod thng c 10% hot cht, l cht dit khun rt hiu qu, k c cc bo t vi khun. Ngoi ra n cn c tc dng dit nm v mt vi loi virus. Do , ha cht ny c hiu qu trong vic st trng nc ao.

Liu lng: Dng liu lng 0.5 - 1 ppm c tc dng phng bnh v x l nc. Dng liu lng 1 - 2 ppm tr cc bnh do vi khun.

Ch : Iodine b gim tc dng trong mi trng c kim cao do phn ng t kh. Do , khi pha thuc nn thm mt t (vi git) cht axit nh nh axit citric (chanh) hay axit axtic (gim) tng cng hiu qu ca thuc.

1.5 EDTA

Tn gi: EDTA (ethylen ditetra acetate)

Tc dng v liu lng s dng

Dng kt ta cc loi kim loi nng nh ng, st, Cadinium ... c trong nc nh hng n tm, nht l trong qu trnh lt xc c bit giai on u trng v hu u trng. Nc ging khoan thng cha nhiu kim loi nht l st, do nn x l EDTA trc khi s dng cho tm ging, liu lng thng dng t 5-10 ppm. EDTA cn c tc dng dit khun v mt s loi virus. Phng bnh v x l nc liu lng thng dng t 0,5 - 1 ppm v tr cc bnh do vi khun liu lng dng t 1 - 2 ppm.

1.6 Thiosulphate natri

Cng thc: Na2S2O3Tn gi: Thiosulphate natri, sodium thiosulphate

C ch tc dng:

Na2S2O3 +Cl2 NaCl Tc dng

40

Bnh ho c thuy sa n

Dng trung ha chlorine d tha trong qu trnh x l nc, c 1 ppm chlorine cn khong 1 ppm thiosulfate trung ha trit . Tuy nhin trong thi gian x l chlorine s b bay hi nh qu trnh sc kh mnh. Sau mt thi gian di >24 gi c sc kh mnh lng chlorine s dng (20-30ppm) c th mt i m khng cn dng n thiosulfate.

II. Thuc v ha cht dit k sinh trng.

2.1 ng Sulfat

Cng thc: CuSO4Tn gi: ng sulphate hay phn xanh

Tnh cht : Sn phm cng nghip kt tinh mu xanh, khng mi v, c th tan trong nc; trong khng kh c th mt nc v kt tinh bin thnh mu trng. Sau khi ht m li bin thnh Sulfat ng ngm nc mu xanh. Nu qu m c th b chy, nhng khng nh hng n cng dng.

Tc dng: CuSO4 c vi cc nguyn sinh ng vt v cc loi to h ng v c mng keo bao quanh c th. Ion Cu2+ kt hp vi albumin to thnh mui kt ta lm ng vn t chc. Sulphat ng thng c dng tr nguyn sinh ng vt k sinh trn tm c, l cht dit to hiu qu. Ngoi ra sulphat ng cn c tc dng dit khun v nm. Tc dng v liu lng ca sulphat ng trong ao nui ph thuc vo mt s yu t, c bit l kim tng s. Ta c cng thc tnh liu lng s dng nh sau:

kim tng s ca nc (ppm)

Lng sulphat ng cn = -----------------------------------------

(ppm) 100

kim thp hn 50 ppm, c ca sulphat ng khng xc nh c do nn cn thn khi s dng, nu kim thp hn 20 ppm th tuyt i khng c s dng ha cht ny. Trong nc c kim cao (hn 250 ppm) sulphat ng b kt ta nhanh chng, nn nu ch x l mt ln th khng tc dng. Sulphat ng kh c cho tm nht l tm con, do cn phi thn trng trong s dng.

Bng cch treo ti CuSO4 ch cho c n, c th cha mt s bnh do vi trng gy nn th nh v bnh k sinh trng.

Lu :

Khi ha tan CuSO4 trong nc, nhit nc khng c cao qu 600C, nu khng d mt tc dng. CuSO4 s tc dng vi cc cht hu c c sn trong ao, v vy cng hiu ca thuc s gim; do cn tng nng khi dng v nn tnh ton k qua thc

41

Bnh ho c thuy sa n

nghim. Phi tnh chnh xc th tch nc trong ao, nu khng, khi s dng CuSO4 vi nng cao qu 0,7 ppm s gy ng c cho c.

2.2 Thuc tm

Cng thc: KMnO4Tn gi: Thuc tm, kali permaganate, potasium permanganate.

Tnh cht: Kt tinh hnh lng tr di nh, mu tm en, khng trong sut, c nh kim mu lam khng mi, d tan trong nc, khi phi hp vi cht hu c hay cht xy ha d n; cn gi trong l mu, c nt. Tnh theo loi kh, hm lng KMnO4 khng c thp hn 99%.

Tc dng: y l dng ha cht tit trng b mt, dng x l cc loi k sinh ngoi, nm, vi khun dng si bm. Nng s dng 4 - 5 ppm (ngm), hay tm trong dung dch 100 ppm trong 5 - 10 pht tr bnh dnh chn hay bnh mang tm. KMnO4 l mt cht oxy ha cht hu c, v c v dit khun cao. V vy, n c tc dng lm gim mc tiu th oxy ca cc qu trnh ha hc, sinh hc. Cht ny cng c s dng cho ha rotenon ( Lawrence, 1965) v antimycine (Marking and Bill, 1976) l nhng ha cht dng dit c.

Theo Turker v Boyd (1977) cho rng KMnO4 rt c i vi vi khun trong nc c hm lng hu c thp. Vi nng 2ppm th 99% vi khun Gram m v 90% vi khun Gram dng b tiu dit. Nguyn l da trn s oxy ha ca MnO4- ph hy cc t bo trn.

Liu lng: Dng 20 ppm KMnO4 ngm tm trong 15 - 30 pht c th dit c cc trng Gyrodactylus, Dactylogyrus v cng c tc dng vi trng bnh xe, hp qun trng. Nhit nc 21 - 300C dng 10 ppm ngm tm 1g30pht n 2g, cha bnh trng m neo Lernaea v bnh do rn c Argulus.

Lu :

Khng nn tm c, tm bng dung dch KMnO4 di nh nng gay gt hoc nh sng chiu thng v KMnO4 d b Oxy ha mt cng dng.

Khi s dng KMnO4 v s lm gi