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ASCARIASIS 蛔蟲症About 1/4 of the world population is infected
Ascaris lumbricoides 蛔蟲
Infection is world-wide distributioncommon in areas where human feaces
are used as fertilizerChildren are more often and mor heavily
infected than adults
The largest Intestinal NematodeMale:15~31 cm x 2~4 mm Female: 22~35 cm x 3~6 mm
Cylindrical and white to tan with tapered endsThe mouth surrounded by 3 lips
Cuticle has both annulations and striations
FemalesDidephic
Ovaries, oviducts & uteri arein the posterior 2/3
Vulva is located 1/3 from the anterior ens
MalesPosterior end curved
Reproductive tube in the posterior half of the body
Has 2 copulatory spicule
Embryonated egg Eggs in faeces
Unfertilised
Trachea
Ingested
Fertilised
Larva hatchesin intestine
Swallowed
Pharynx
Adults insmall intestine
2-cell stageAdvancedcleavage
Infectivestage (L2)
Diagnosticstages
MAN
EXTERNALENVIRNOMENT
L4
200,000~250,000eggs per day
3~4 wks
Life Cycle of Ascaris lumbricoides
Lungs (L3)
Portal circulation
Pathogensis 致病機轉
Abdominal pain, nausea, diarrhoea and vomitingImpaired absorption (吸收不良)
Malnutrition (營養不良)
Amount of worms infected 感染蟲數Effects of visceral larval migration (VLM) 內臟幼蟲移行Mechanical effects due to adult worms 成蟲機械式傷害Nutritional deficiencies
Larvae migration (幼蟲移行)Mechanical damage (機械式傷害) cause
inflammatory (發炎), bacterial infection (細菌性感染) and hypersensitive reaction 過敏反應
In lung cause Loeffler's syndrome
Coughing, bronchial asthma and pneumonia- like symptoms
Infiltartion of eosinphils, macrophages, and epitheloid cells around the larvae
Allergic reaction consisting of dyspena, a dry or productive cough,transient eosinophilia, wheezing ot coarse rales, fever, and a chest X-ray suggestive of viral pneumonia.
Sputum contain eosinophils, Charcot-Leyden crystal and sometimes larvae
Heavy Infection 重度感染
Pass or vomit of worms 排出或吐出成蟲Intestinal obstruction by worm bolus 腸阻塞Intestinal perforation 腸穿孔Bile duct and pancreatic duct obstruction 阻塞膽管及胰管→ cholangitis 化膿性膽道炎
multiple liver absceses 多發性肝膿腫ascarid chronic pancreatitis 慢性胰臟炎
Can be fatal
Atopic Ascariasis蛔蟲異位感染
Bile ductPancreatic ductLiverPeritoneal cavityKidneyAppendixPleural cavityUpper respiratory tract
Adult in liver
Adult in bile duct
Liver egg granuloma
Fertilized egg 受精卵Unfertilized egg 未受精卵Decorticated egg 去蛋白膜卵
Finding A. lumbricoides eggs in faeces
through the anus or mouth
Identifying A. lumbricoides worms expelled
Laboratory DiagnosisFertilized females lay about 200,000 eggs per day
A. lumbricoides eggs
Embryonated egg 胎蟲卵 (infective)pale yellow or colourlesscontains a larva (R-form, 1st or 2nd stage )
Fertilized egg 受精卵oval or round, 60 x 40 mm, yellowish brown egg shell covered by an uneven albuminous coatcontains a central grandular mass
Unfertilized egg 未受精卵elongated, 90 x 45 mm, darker and more albuminouscontains a central mass of large refractile grandules
Decorticated egg 去蛋白膜卵pale yellow or colourlesssmooth egg shell no albuminous coat
Prevention and Control預防及控制
•Providing and using adequate latrines•Avoding the use of human feaces as fertilizer•Treating infected individuals as part of a control programme especially children
Preventing soil becoming faecally polluted by
•Washing the hands before eating•Avoid the eating of uncooked vegetables, green salads and fruits
Preventing eggs being ingested by
Treatment
Pyrantel pamoatesingle dose, 10 mg/kg, max. 750 mg/adultLevamisolesingle dose, children (5 mg/kg), adult (150 mg)
Mebendazolesingle dose, twice a day, 100 mg/each
Albendazolesingle dose, children from 2~12 yr. (200 mg), adult (400 mg)
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