SSome epidemiological aspects of classical swine fever in ...vetarhiv.vef.unizg.hr/papers/2011-81-1-6.pdf · ooccurred in the eastern part of Croatia in three municipalities of the

51ISSN 0372-5480Printed in Croatia

VETERINARSKI ARHIV 81 (1), 51-66, 2011

Some epidemiological aspects of classical swine fever in Croatia Some epidemiological aspects of classical swine fever in Croatia (2006-2008)(2006-2008)

Marina PavlakMarina Pavlak11*, Vanja Vrkić*, Vanja Vrkić 2 2, Denis Cvitković, Denis Cvitković11 Sanja Šeparović Sanja Šeparović33, , Anđelko GašparAnđelko Gašpar44, and Marko Tadić, and Marko Tadić11

11Department of Veterinary Economics and Analytic Epidemiology, Faculty of Veterinary Medicine, University Department of Veterinary Economics and Analytic Epidemiology, Faculty of Veterinary Medicine, University of Zagreb, Zagreb, Croatiaof Zagreb, Zagreb, Croatia

22Department of Parasitology and Parasitic Diseases with Clinic, Faculty of Veterinary Medicine, University Department of Parasitology and Parasitic Diseases with Clinic, Faculty of Veterinary Medicine, University of Zagreb, Zagreb, Croatiaof Zagreb, Zagreb, Croatia

33State Veterinary Administration, Ministry of Agricultural, Fisheries and Rural DevelopmentState Veterinary Administration, Ministry of Agricultural, Fisheries and Rural Development44Croatian Veterinary ChamberCroatian Veterinary Chamber

PAVLAK, M., V. VRKIĆ, D. CVITKOVIĆ, S. ŠEPAROVIĆ, A. GAŠPAR, M. PAVLAK, M., V. VRKIĆ, D. CVITKOVIĆ, S. ŠEPAROVIĆ, A. GAŠPAR, M. TADIĆTADIĆ: : Some epidemiological aspects of classical swine fever in Croatia (2006-Some epidemiological aspects of classical swine fever in Croatia (2006-2008).2008). Vet. arhiv 81, 51-66, 2011. Vet. arhiv 81, 51-66, 2011.

ABSTRACTABSTRACT

The aim of tThe aim of this study was to present some aspects of epidemiological features of the classical swine fever his study was to present some aspects of epidemiological features of the classical swine fever (CSF) epidemic in Croatia between 2006 and 2008. Pig production before the CSF epidemic in the Vukovar-(CSF) epidemic in Croatia between 2006 and 2008. Pig production before the CSF epidemic in the Vukovar-Sirmium County and the infl uence of some risk factors such as swill feeding and contact with wild boars, as Sirmium County and the infl uence of some risk factors such as swill feeding and contact with wild boars, as well as temporal characteristics of the occurrence of CSF outbreaks have been investigated. The temporal data well as temporal characteristics of the occurrence of CSF outbreaks have been investigated. The temporal data related to the occurrence of CSF outbreaks in Croatia and the data on pig production in the Vukovar-Sirmium related to the occurrence of CSF outbreaks in Croatia and the data on pig production in the Vukovar-Sirmium County have been analyzed. The data related to pig production included the number of agricultural households County have been analyzed. The data related to pig production included the number of agricultural households keeping pigs, that is, the number of small pig farms and number of pigs in the Vukovar-Sirmium County. The keeping pigs, that is, the number of small pig farms and number of pigs in the Vukovar-Sirmium County. The data related to the occurrence of the CSF epidemic in Croatia included the days of occurrence of outbreaks data related to the occurrence of the CSF epidemic in Croatia included the days of occurrence of outbreaks and the time interval between two outbreaks from 17 July 2006 until 7 May 2008. The fi rst outbreak of CSF and the time interval between two outbreaks from 17 July 2006 until 7 May 2008. The fi rst outbreak of CSF occurred in the eastern part of Croatia in three municipalities of the Vukovar-Sirmium County, then spread into occurred in the eastern part of Croatia in three municipalities of the Vukovar-Sirmium County, then spread into another 11 counties. At the time of CSF occurrence, there were 1,178 small pig farms observed and 16,034 pigs another 11 counties. At the time of CSF occurrence, there were 1,178 small pig farms observed and 16,034 pigs in that area. From the point of view of risk factors, at 532 (45.16%) out of the 1,178 observed pig farms, pigs in that area. From the point of view of risk factors, at 532 (45.16%) out of the 1,178 observed pig farms, pigs were kept extensively while at 252 of them (21.39%) pigs were swill-fed. The analysis of the distribution of the were kept extensively while at 252 of them (21.39%) pigs were swill-fed. The analysis of the distribution of the number of CSF outbreaks by day diagnosed shows that new outbreaks were recorded 70 times at intervals of a number of CSF outbreaks by day diagnosed shows that new outbreaks were recorded 70 times at intervals of a minimum of one day and maximum of 86 days during the 621 days of the epidemic. The time interval between minimum of one day and maximum of 86 days during the 621 days of the epidemic. The time interval between two new outbreaks was usually up to 10 days, mostly one day. The highest number of new outbreaks registered two new outbreaks was usually up to 10 days, mostly one day. The highest number of new outbreaks registered in the same day was 8 on the 235in the same day was 8 on the 235thth day from the beginning of the epidemic. day from the beginning of the epidemic.

Key words: Key words: classical swine fever,classical swine fever, Croatia, occurrence, time interval, risk factors Croatia, occurrence, time interval, risk factors

*Corresponding author:Marina Pavlak, Ph.D, DVM, Faculty of Veterinary Medicine, University of Zagreb, Heinzelova 55, 10000 Zagreb, Croatia, Phone: +385 1 23 90 134; Fax: +385 1 24 41 390; E-mail: [email protected]

52

M. Pavlak et al.: Classical swine fever in Croatia (2006-2008)

Vet. arhiv 81 (1), 51-66, 2011

Introduction Introduction Classical swine fever (CSF) is the most important contagious viral infectious disease Classical swine fever (CSF) is the most important contagious viral infectious disease

affecting domestic pigs as well as wild boars world-wide. The disease is caused by the affecting domestic pigs as well as wild boars world-wide. The disease is caused by the classical swine fever virus belonging to the classical swine fever virus belonging to the PestivirusPestivirus genus of the genus of the FlaviviridaeFlaviviridae family family ((VAN OIRSCHOTVAN OIRSCHOT, 1992; MOENNIG, et al., 2003; PATON and GREISER-WILKE, 2003, 1992; MOENNIG, et al., 2003; PATON and GREISER-WILKE, 2003). ).

CSF occurs world-wide, including Europe, Central and South America, Asia and CSF occurs world-wide, including Europe, Central and South America, Asia and Africa (Africa (EDWARDS et al., 2000EDWARDS et al., 2000). The disease was eradicated in Australia in 1963, Canada ). The disease was eradicated in Australia in 1963, Canada in 1964 and the United States in 1977 (in 1964 and the United States in 1977 (ELBERSELBERS et al., 1999 et al., 1999). The European Union (EU) ). The European Union (EU) also succeeded in eradicating CSF and reaching the status of CSF free countries (OIE, also succeeded in eradicating CSF and reaching the status of CSF free countries (OIE, 2008). In the early 1990s, the EU control program was based on a strategy of non-2008). In the early 1990s, the EU control program was based on a strategy of non-vaccination, stamping-out and intensive surveillance supported by veterinary legislation vaccination, stamping-out and intensive surveillance supported by veterinary legislation and zoo-sanitary measures (and zoo-sanitary measures (ELBERSELBERS et al., 1999; MOENNIG et al., 2003 et al., 1999; MOENNIG et al., 2003). However, the ). However, the virus was periodically reintroduced into domestic pigs through wild boars (virus was periodically reintroduced into domestic pigs through wild boars (KADEN, 1999; KADEN, 1999; FRITZMEIER et al., 2000; VOS et al., 2003FRITZMEIER et al., 2000; VOS et al., 2003) or through imported pigs and pig products ) or through imported pigs and pig products ((GIBBENSGIBBENS et al., 2000; VOS et al., 2003 et al., 2000; VOS et al., 2003), swill feeding (), swill feeding (FRITZEMEIERFRITZEMEIER et al., 2000; et al., 2000; MOENNIG,MOENNIG, 2003; VOS et al., 20032003; VOS et al., 2003) and semen () and semen (ELBERS et al., 1999; HENNECKEN et al., 2000ELBERS et al., 1999; HENNECKEN et al., 2000). According ). According to data of the World Organization of Animal Health (OIE), in the period between 1996 and to data of the World Organization of Animal Health (OIE), in the period between 1996 and 2009, following the EU policy of non-vaccination, intensive surveillance and eradication, 2009, following the EU policy of non-vaccination, intensive surveillance and eradication, CSF outbreaks were observed in 24 European countries, including 16 EU member states CSF outbreaks were observed in 24 European countries, including 16 EU member states (Table 1). The most numerous and economically most important outbreaks occurred in (Table 1). The most numerous and economically most important outbreaks occurred in industrialized countries such as Germany, the Netherlands, Belgium, Spain and Italy industrialized countries such as Germany, the Netherlands, Belgium, Spain and Italy ((MEUWISSEN et al., 1999; FELIZIANI et al., 2005; BOLZONI and DE LEO, 2007MEUWISSEN et al., 1999; FELIZIANI et al., 2005; BOLZONI and DE LEO, 2007). Several ). Several CSF epidemics occurred in the Netherlands in 1997-1998. A total of 429 outbreaks CSF epidemics occurred in the Netherlands in 1997-1998. A total of 429 outbreaks was observed and approximately 700,000 pigs from these herds were slaughtered, was observed and approximately 700,000 pigs from these herds were slaughtered, consequently causing important economic losses (consequently causing important economic losses (ELBERS et al., 1999; PLUIMERS et al., ELBERS et al., 1999; PLUIMERS et al., 1999; MANGEN et al., 2002; KLINKENBERG et al., 2005; VOS et al., 20051999; MANGEN et al., 2002; KLINKENBERG et al., 2005; VOS et al., 2005). In Belgium, in ). In Belgium, in 1997 eight herds in different locations were confi rmed to be positive and 46,561 pigs 1997 eight herds in different locations were confi rmed to be positive and 46,561 pigs were slaughtered in order to put the epidemics under control (were slaughtered in order to put the epidemics under control (MINTIENS et al., 2001MINTIENS et al., 2001). In ). In Spain in 2001-2002, the disease was confi rmed in 49 herds and 291,058 animals were Spain in 2001-2002, the disease was confi rmed in 49 herds and 291,058 animals were slaughtered (slaughtered (ALLEPUZ et al., 2007ALLEPUZ et al., 2007). The eradication of CSF is especially challenging in ). The eradication of CSF is especially challenging in countries where CSF is spread in wild boar populations, which could be the main source countries where CSF is spread in wild boar populations, which could be the main source of infection (of infection (LADDOMADA,LADDOMADA, 2000; 2000; ARTOISARTOIS et al., 2002; ŽUPANČIĆ et al., 2002; ROIĆ et al., et al., 2002; ŽUPANČIĆ et al., 2002; ROIĆ et al., 20072007). In Germany between 1990 and 1998 there were 424 outbreaks of CFS in domestic ). In Germany between 1990 and 1998 there were 424 outbreaks of CFS in domestic pigs and most of them were due to direct or indirect contact with infected wild boars pigs and most of them were due to direct or indirect contact with infected wild boars ((FRITZMEIER et al., 2000FRITZMEIER et al., 2000). ).

In Croatia the strategy of non-vaccination and eradication was introduced in January In Croatia the strategy of non-vaccination and eradication was introduced in January 2005. Until then vaccination and eradication were the main preventive measures applied 2005. Until then vaccination and eradication were the main preventive measures applied in order to prevent the introduction and spread of CSF in the country. In spite of obligatory in order to prevent the introduction and spread of CSF in the country. In spite of obligatory

53


Vet. arhiv 81 (1), 51-66, 2011

vaccination, several outbreaks of CSF at small farms were recorded in 1996 and 1997 vaccination, several outbreaks of CSF at small farms were recorded in 1996 and 1997 (Table 1) ((Table 1) (JEMERŠIĆ JEMERŠIĆ et al., 2003et al., 2003). After introducing the policy of non-vaccination, CSF ). After introducing the policy of non-vaccination, CSF was detected for the fi rst time on 17 July 2006 in the Vukovar-Sirmium County lasting until was detected for the fi rst time on 17 July 2006 in the Vukovar-Sirmium County lasting until 7 May 2008, when it was fi nally resolved. From 17 July 2006 until 30 March 2007 there 7 May 2008, when it was fi nally resolved. From 17 July 2006 until 30 March 2007 there were 106 outbreaks of CSF and 3,917 pigs were destroyed. Between July and December were 106 outbreaks of CSF and 3,917 pigs were destroyed. Between July and December 2006, 11,945 pigs were destroyed at 91 locations in four counties. From 1 January 2007 2006, 11,945 pigs were destroyed at 91 locations in four counties. From 1 January 2007 until 25 March 2007, CSF was detected in 59 small private farms in 9 counties (until 25 March 2007, CSF was detected in 59 small private farms in 9 counties (PAVLAK PAVLAK et alet al.., 2007a; 2007b, 2007a; 2007b). According to the report of the World Organization of Animal Health, ). According to the report of the World Organization of Animal Health, in the course of the CSF epidemic in Croatia, there were 129 outbreaks including 13,796 in the course of the CSF epidemic in Croatia, there were 129 outbreaks including 13,796 susceptible domestic pigs. Out of that number, 727 pigs showed clinical symptoms while susceptible domestic pigs. Out of that number, 727 pigs showed clinical symptoms while 318 died. Another 12,297 pigs were destroyed and 3 animals slaughtered.318 died. Another 12,297 pigs were destroyed and 3 animals slaughtered.

CSF causes important economic losses to the pork industry world-wide, especially CSF causes important economic losses to the pork industry world-wide, especially in an export-oriented country (in an export-oriented country (ELBERSELBERS et al., 1999; et al., 1999; MEUWISSEN MEUWISSEN et al., 1999; et al., 1999; EDWARDSEDWARDS et et al., 2000al., 2000). Therefore it is advisable to analyze the economic impacts and epidemiological ). Therefore it is advisable to analyze the economic impacts and epidemiological characteristics of CSF epidemic. The aim of this study is to present some epidemiological characteristics of CSF epidemic. The aim of this study is to present some epidemiological features of the CSF epidemic in Croatia in 2006-2008. First, we analyzed the pig features of the CSF epidemic in Croatia in 2006-2008. First, we analyzed the pig production in the Vukovar-Sirmium County, taking into account the number of agricultural production in the Vukovar-Sirmium County, taking into account the number of agricultural households and number of pigs. Furthermore, we analyzed some risk factors such as swill households and number of pigs. Furthermore, we analyzed some risk factors such as swill feeding and contact with wild boars at the beginning on the CSF epidemic in the Vukovar-feeding and contact with wild boars at the beginning on the CSF epidemic in the Vukovar-Sirmium County. Finally we analyzed the temporal characteristics of the occurrence of Sirmium County. Finally we analyzed the temporal characteristics of the occurrence of outbreaks during the CSF epidemic in Croatia in 2006-2008.outbreaks during the CSF epidemic in Croatia in 2006-2008.

Materials and methodsMaterials and methodsThe data related to the occurrence of the CSF epidemic in Croatia as well as the data The data related to the occurrence of the CSF epidemic in Croatia as well as the data

related to pig production in the Vukovar-Sirmium County, where the CSF epidemic started, related to pig production in the Vukovar-Sirmium County, where the CSF epidemic started, have been analyzed. These data include the total number of agricultural households, the have been analyzed. These data include the total number of agricultural households, the number of agricultural households keeping pigs, e. g. number of small pig farms and the number of agricultural households keeping pigs, e. g. number of small pig farms and the number of pigs in the Vukovar-Sirmium County. The data were collected from the Central number of pigs in the Vukovar-Sirmium County. The data were collected from the Central Bureau of Statistics of the Republic of Croatia. Bureau of Statistics of the Republic of Croatia.

The data used for risk assesment, such as swill feeding and extensive farming where The data used for risk assesment, such as swill feeding and extensive farming where contact with wild boars was possible, were based on the information collected by the contact with wild boars was possible, were based on the information collected by the State Veterinary Administration at the beginning of the CSF epidemic in the Vukovar-State Veterinary Administration at the beginning of the CSF epidemic in the Vukovar-Sirmium County in 2006, through a questionnaire within the framework of the control of Sirmium County in 2006, through a questionnaire within the framework of the control of the CSF epidemic. The response rate for the answer about swill feeding was 91% and for the CSF epidemic. The response rate for the answer about swill feeding was 91% and for the type of farming (extensive or intensive farming) was 79%. the type of farming (extensive or intensive farming) was 79%.

In the analysis of the occurrence of the CSF epidemic in Croatia four variables were In the analysis of the occurrence of the CSF epidemic in Croatia four variables were considered: the number of occurrence of new outbreaks, e. g. the number of confi rmed considered: the number of occurrence of new outbreaks, e. g. the number of confi rmed CSF outbreaks by day diagnosed (Var1), the number of new outbreaks (Var2), the intervals CSF outbreaks by day diagnosed (Var1), the number of new outbreaks (Var2), the intervals

54


Vet. arhiv 81 (1), 51-66, 2011

between two new outbreaks in days (Var3) and the cumulative interval between two between two new outbreaks in days (Var3) and the cumulative interval between two outbreaks in days (Var4). The data used included the period between 17 July 2006 and 7 outbreaks in days (Var4). The data used included the period between 17 July 2006 and 7 May 2008. The data about the number of occurrences of CSF outbreaks were obtained May 2008. The data about the number of occurrences of CSF outbreaks were obtained from the State Veterinary Administration of the Ministry of Agriculture, Fisheries and from the State Veterinary Administration of the Ministry of Agriculture, Fisheries and Rural Development and from the World Animal Health Information Database of the Rural Development and from the World Animal Health Information Database of the World Organization for Animal HealthWorld Organization for Animal Health

All results were analyzed by Statistica 8.0 and Excel 2002. The risk factors were All results were analyzed by Statistica 8.0 and Excel 2002. The risk factors were estimated through the odd ratio based on the ratio of probability of an event occurring estimated through the odd ratio based on the ratio of probability of an event occurring to the probability of it not occurring (to the probability of it not occurring (MARTIN et al., 1988; THRUSFIELD, 1995MARTIN et al., 1988; THRUSFIELD, 1995) using ) using WinEpiscope 2.0. WinEpiscope 2.0.

Results Results The fi rst outbreak of CSF, after a 7 year absence in the country (Table 1), occurred in The fi rst outbreak of CSF, after a 7 year absence in the country (Table 1), occurred in

2006 in the eastern part of Croatia in the Vukovar-Sirmium County, spreading into 11 other 2006 in the eastern part of Croatia in the Vukovar-Sirmium County, spreading into 11 other counties in the central part of the country. In the Vukovar-Sirmium County herds located counties in the central part of the country. In the Vukovar-Sirmium County herds located in three municipalities were struck, one of which (Municipality 1) is the area with the in three municipalities were struck, one of which (Municipality 1) is the area with the highest number of pigs in this county. The number of pigs in this municipality amounted highest number of pigs in this county. The number of pigs in this municipality amounted to 26,134 which was 13.94% of the total number of pigs in the Vukovar-Sirmium County to 26,134 which was 13.94% of the total number of pigs in the Vukovar-Sirmium County in 2003. The total number of agricultural households, the total number of agricultural in 2003. The total number of agricultural households, the total number of agricultural households keeping pigs, that is, the number of small pig farms and the number of pigs households keeping pigs, that is, the number of small pig farms and the number of pigs in this county and in the affected municipalities are presented in Table 2. It may be seen in this county and in the affected municipalities are presented in Table 2. It may be seen that out of 26,316 agricultural households in this county, 16,915 of them (64.28%) are that out of 26,316 agricultural households in this county, 16,915 of them (64.28%) are small pig farms. Out of total number of small pig farms in the Vukovar-Sirmium County, small pig farms. Out of total number of small pig farms in the Vukovar-Sirmium County, 2,235 farms (13.21%) were located in three municipalities with CSF outbreaks. Out of the 2,235 farms (13.21%) were located in three municipalities with CSF outbreaks. Out of the total number of pigs in the Vukovar-Sirmium County in 2003, 33,137 pigs (17.67%) were total number of pigs in the Vukovar-Sirmium County in 2003, 33,137 pigs (17.67%) were located in these three municipalities and out of that number 78.87% pigs were located in located in these three municipalities and out of that number 78.87% pigs were located in Municipality 1. Municipality 1.

When the CSF epidemic started, 1,178 pig farms and 16,034 pigs were observed. In When the CSF epidemic started, 1,178 pig farms and 16,034 pigs were observed. In 55 (4.69%) observed farms, 868 pigs (5.41%) were euthanized (Table 3). 55 (4.69%) observed farms, 868 pigs (5.41%) were euthanized (Table 3).

According to breeding type, piglets and breeding pigs are the most frequent types of According to breeding type, piglets and breeding pigs are the most frequent types of pigs in households. Consequently piglets and breeding pigs were the most frequent types pigs in households. Consequently piglets and breeding pigs were the most frequent types of pigs euthanized during the eradication (Table 4). of pigs euthanized during the eradication (Table 4).

From the point of view of risk factors, out of 1,178 observed pig farms, on 532 From the point of view of risk factors, out of 1,178 observed pig farms, on 532 farms (45.16%) pigs were kept extensively, while on 252 farms (21.39%) pigs were swill-farms (45.16%) pigs were kept extensively, while on 252 farms (21.39%) pigs were swill-fed (Table 5). Extensive farming means that pigs were kept free on land where contact fed (Table 5). Extensive farming means that pigs were kept free on land where contact between domestic pigs and wild boars was possible. between domestic pigs and wild boars was possible.

Basic statistic data of the occurrence of CSF outbreaks in Croatia from 2006 to 2008, Basic statistic data of the occurrence of CSF outbreaks in Croatia from 2006 to 2008, including the number of the occurrence of new outbreaks e. g. number of confi rmed including the number of the occurrence of new outbreaks e. g. number of confi rmed

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Vet. arhiv 81 (1), 51-66, 2011

Tabl

e 1.

Cla

ssic

al sw

ine

feve

r out

brea

ks in

dom

estic

swin

e in

Eur

opea

n co

untri

es in

per

iod

from

199

2 to

200

8

Cou

ntry

Year

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

Alb

ania

3-

--

--

3-

--

--

-A

ustri

a2

--

--

1-

--

--

--

Bel

gium

-8

--

--

1-

--

--

-B

osni

a an

d H

erze

govi

na-

43-

-1

5278

8423

--

--

Bul

garia

18

84

11

3211

4-

32

1C

roat

ia7

10-

2-

--

--

-14

115

-C

zech

Rep

ublic

22

2113

--

--

--

--

-F

Y R

epub

lic o

f Mac

edon

ia-

--

1915

3212

38

--

--

Fran

ce-

--

--

-9

137

--

--

FRY

(Ser

bia

and

Mon

tene

gro)

11

873

6269

172

128

5244

110

--

--

Ger

man

y4

4411

415

176

378

462

383

-8

--

Hun

gary

--

--

--

--

--

-61

81Ita

ly49

5518

93

5-

1-

--

--

Latv

ia2

--

--

--

--

--

--

Luxe

mbu

rg-

--

--

777

1-

--

--

The

Net

herla

nds

-42

45

--

--

--

--

--

Rom

ania

--

--

-1

5415

518

2-

--

-R

ussi

a26

1011

1416

14-

64

3-

81

Slov

akia

2596

9014

2140

4837

12-

--

3Sl

oven

ia1

--

--

--

--

--

--

Spai

n-

7821

--

3316

--

--

--

Switz

erla

nd-

--

49-

--

--

--

--

Ukr

aine

1-

47-

-2

--

--

--

Uni

ted

Kin

gdom

--

--

16-

--

--

--

-So

urce

: Wor

d O

rgan

izat

ion

for A

nim

al H

ealth

- Offi

ce In

tern

atio

nal d

es E

pizo

otie

s (O

IE),

Paris

(Dat

a fr

om 1

996

to 2

004

- Han

dsta

tus,

and

from

20

05 to

200

8 -W

AH

ID)

56


Vet. arhiv 81 (1), 51-66, 2011

Table 2. Number of agricultural households and pig in Croatia, in Vukovar- Sirmium County and in the three affected municipalities before the occurrence of CSF epidemic

No. of agricultural households

No. of agricultural households keeping pigs Number of pigs

Republic of Croatia 448.532 214.814 1.726.895Vukovar-Sirmium County 26.316 16.915 187.497Municipality 1 1.703 1.182 26.134Municipality 2 1.058 636 4.271Municipality 3 1.223 417 2.732Total in three municipalities 3.984 2.235 33.137

Source: Agricultural Census 2003, Crostat Databases - Central Bureau of Statistics, Republic of Croatia

Table 3. Number of observed households keeping pigs and number of pigs as well as number of euthanized pigs in the affected municipalities in the Vukovar-Sirmium County at the beginning of

the epidemic

District

No. of observed households

keeping pigs

No. of observed households by euthanized pigs

No. of observed pigs No. of euthanized pigs

N N % N N %Municipality 1 426 2 0.47 8.802 47 0.53Municipality 2 459 41 8.93 4.406 592 13.44Municipality 3 293 12 4.10 2.826 229 8.10Total 1.178 55 4.67 16.034 868 5.41

57


Vet. arhiv 81 (1), 51-66, 2011

Tabl

e 4.

Num

ber o

f obs

erve

d ho

useh

olds

and

num

ber o

f obs

erve

d an

d eu

than

ized

pig

s acc

ordi

ng to

mun

icip

aliti

es in

rela

tion

to

bree

ding

type

at t

he b

egin

ning

of t

he e

pide

mic

Mun

icip

ality

1M

unic

ipal

ity 2

Mun

icip

ality

3N

o. o

f ob

serv

edN

o. o

f eu

than

ized

% o

f eu

than

ized

No.

of

obse

rved

No.

of

euth

aniz

ed%

of

euth

aniz

edN

o. o

f ob

serv

edN

o. o

f eu

than

ized

% o

f eu

than

ized

Sow

s11

783

0.25

788

126

15.9

939

252

13.2

7Pi

glet

s30

0040

1.33

1963

211

10.7

515

9212

67.

91B

reed

ing

pigs

4577

40.

0916

3925

315

.44

833

455.

40B

oars

470

016

212

.50

96

66.6

6To

tal

8802

470,

5344

0659

213

.44

2826

229

8.10

Tabl

e 5.

Num

ber o

f obs

erve

d ho

useh

olds

by

type

of f

arm

ing

and

by p

igs f

ed w

ith sw

ill in

the

CSF

affe

cted

mun

icip

aliti

es in

the

Vuk

ovar

-Sirm

ium

Cou

nty

at th

e be

ginn

ing

of C

SF e

pide

mic

Mun

icip

ality

No.

of h

ouse

hold

s ke

epin

g pi

gs

Type

of f

arm

ing

Swill

feed

ing

Inte

nsiv

e fa

rmin

gEx

tens

ive

farm

ing

No

data

Yes

No

No

data

Mun

icip

ality

142

614

419

983

6930

552

Mun

icip

ality

245

910

827

774

131

289

39M

unic

ipal

ity 3

293

137

5610

052

222

19To

tal

1178

389

532

257

252

826

110

Tabl

e 6.

Bas

is st

atis

tic d

ata

of o

ccur

renc

e of

CSF

out

brea

ks in

Cro

atia

from

200

6 to

200

8

Varia

bles

*N

Mea

nC

onfi d

ence

+

95%

Confi d

ence

- 9

5%M

inM

axR

ange

Varia

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Vet. arhiv 81 (1), 51-66, 2011

Var1:Var3: r = 0.0363; P = 0.7658; y = 7.923 + 0.0267*xFig. 1. Time distribution of CSF new outbreaks (Var3) by days diagnosed in 2006-2008 in Croatia

Fig. 2. Time frequency (in days) between new CSF outbreaks in 2006-2008 in Croatia

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Vet. arhiv 81 (1), 51-66, 2011

Var1:Var4: r = 0,9735; P = 00,0000; y = 55,8199 + 6,9918*xFig. 3. Cumulative time distribution of occurrence of CSF new outbreaks in 2006-2008 in Croatia

Var1:Var2: r = -0,0732; P = 0,5473; y = 2,077 - 0,0054*xFig. 4. Distribution of number of CSF outbreaks (Var2) by ordinal number of days diagnosed

(Var1) in 2006-2008 in Croatia

60


CSF outbreks by day diagnosed (Var1), the number of new outbreaks (Var2), the interval CSF outbreks by day diagnosed (Var1), the number of new outbreaks (Var2), the interval between two new outbreaks in days (Var3) and the cumulative interval between two new between two new outbreaks in days (Var3) and the cumulative interval between two new outbreaks in days (Var4) are presented in Table 6. The time distribution of CSF outbreaks outbreaks in days (Var4) are presented in Table 6. The time distribution of CSF outbreaks is shown in Figures 1-4. It may be seen that 70 new outbreaks by day diagnosed were is shown in Figures 1-4. It may be seen that 70 new outbreaks by day diagnosed were recorded (Fig. 1). The interval between two new outbreaks was a minimum of 1 day and recorded (Fig. 1). The interval between two new outbreaks was a minimum of 1 day and a maximum of 86 days (Fig. 2) during the 621 days of the epidemic (Fig. 3). The most a maximum of 86 days (Fig. 2) during the 621 days of the epidemic (Fig. 3). The most frequent interval between two outbreaks was one day (Fig. 1). Most of the new outbreaks frequent interval between two outbreaks was one day (Fig. 1). Most of the new outbreaks were observed within a 10-day period. Only in a few cases was the time interval between were observed within a 10-day period. Only in a few cases was the time interval between two new outbreaks longer than 10 days (Fig. 2). two new outbreaks longer than 10 days (Fig. 2).

The pattern of outbreaks in relation to the time of occurrence of new outbreaks is The pattern of outbreaks in relation to the time of occurrence of new outbreaks is presented in Figures 4 and 5. It shows that one new outbreak per day was identifi ed 42 presented in Figures 4 and 5. It shows that one new outbreak per day was identifi ed 42 times. On the other hand, 8 new outbreaks in the same day were observed only once. The times. On the other hand, 8 new outbreaks in the same day were observed only once. The highest number of outbreaks (8 outbreaks in the same day) was observed on the 235highest number of outbreaks (8 outbreaks in the same day) was observed on the 235thth day day of the epidemic.of the epidemic.

DiscussionDiscussionIn the early 1990s, the EU adopted a non-vaccination control policy (Council In the early 1990s, the EU adopted a non-vaccination control policy (Council

Directive 2001/89/EC), e. g. the control strategy was based on eradication and intensive Directive 2001/89/EC), e. g. the control strategy was based on eradication and intensive surveillance supported by veterinary legislation and zoo-sanitary measures. This involved surveillance supported by veterinary legislation and zoo-sanitary measures. This involved

Fig. 5. Frequency of new outbreaks of CSF in 2006-2008 in Croatia

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movement restrictions and culling of infected and healthy but susceptible animals within movement restrictions and culling of infected and healthy but susceptible animals within a 3 km area from the source of the infection (a 3 km area from the source of the infection (ELBERSELBERS et al., 1999; MOENNIG et al., 2003; et al., 1999; MOENNIG et al., 2003; COHEN et al., 2007COHEN et al., 2007). The advantage of this strategy is in the stimulation of free market ). The advantage of this strategy is in the stimulation of free market trade of animal products between countries who have adopted this strategy. Economic trade of animal products between countries who have adopted this strategy. Economic calculations indicated that the costs of vaccination could be higher than costs of application calculations indicated that the costs of vaccination could be higher than costs of application of control measures (of control measures (COHEN et al., 2007COHEN et al., 2007). ).

After introducing the policy of non-vaccination in Croatia in January 2005 (Offi cial After introducing the policy of non-vaccination in Croatia in January 2005 (Offi cial Gazette, 187/04), CSF was detected for the fi rst time on 17 July 2006 in the Vukovar-Gazette, 187/04), CSF was detected for the fi rst time on 17 July 2006 in the Vukovar-Sirmium County, located in the eastern part of Croatia. The outbreaks were observed in Sirmium County, located in the eastern part of Croatia. The outbreaks were observed in three municipalities located in the eastern part of the Vukovar-Sirmiumin County with three municipalities located in the eastern part of the Vukovar-Sirmiumin County with numerous households keeping pigs, i.e. small pig farms, in a relatively small area. numerous households keeping pigs, i.e. small pig farms, in a relatively small area.

According to the Agricultural Census of Central Bureau of Statistics of the Republic According to the Agricultural Census of Central Bureau of Statistics of the Republic of Croatia, the Vukovar-Sirmium County is one of three counties with the highest number of Croatia, the Vukovar-Sirmium County is one of three counties with the highest number of pigs in Croatia. In 2003, 7.87% of agricultural householders keeping pigs and 10.85% of pigs in Croatia. In 2003, 7.87% of agricultural householders keeping pigs and 10.85% of pigs in Croatia were located in the Vukovar-Sirmium County. Out of the total number of pigs in Croatia were located in the Vukovar-Sirmium County. Out of the total number of pigs in the Vukovar-Sirmium County, 13.21% of small pig farms and 17.67% of of pigs in the Vukovar-Sirmium County, 13.21% of small pig farms and 17.67% of pigs were located in three municipalities affected by CSF. The total area of these three pigs were located in three municipalities affected by CSF. The total area of these three municipalities is 251.51 kmmunicipalities is 251.51 km2,2, where there were 2,235 small pig farms and 33,137 pigs in where there were 2,235 small pig farms and 33,137 pigs in 2003. Most of pig farms (1,182 or 52.86%) were located in Municipality 1 (area of 122.89 2003. Most of pig farms (1,182 or 52.86%) were located in Municipality 1 (area of 122.89 kmkm22) with the highest number of pigs (26,124) in the Vukovar-Sirmium County. However, ) with the highest number of pigs (26,124) in the Vukovar-Sirmium County. However, the primary outbreaks were observed in Municipality 2 which covers a much smaller area the primary outbreaks were observed in Municipality 2 which covers a much smaller area (28.36 km(28.36 km22) with a much smaller number of pigs (4,271), but in this municipality there ) with a much smaller number of pigs (4,271), but in this municipality there are many small pig farms located at a short distance from each other. Consequently, most are many small pig farms located at a short distance from each other. Consequently, most of observed households, as well as most households where the method of eradication of observed households, as well as most households where the method of eradication was applied, were in Municipality 2. Out of 1,178 observed households and out of 55 was applied, were in Municipality 2. Out of 1,178 observed households and out of 55 observed households with euthanized pigs, 38.96% households and 74.55% households observed households with euthanized pigs, 38.96% households and 74.55% households with euthanized pigs were located in Municipality 2 (Table 3). The highest number of with euthanized pigs were located in Municipality 2 (Table 3). The highest number of euthanized pigs (68.20%) was also observed in this area. The CSF occurrences in other euthanized pigs (68.20%) was also observed in this area. The CSF occurrences in other European countries (European countries (ALLEPUZ et al., 2007; BOLZONI and DE LEO, 2007; FELIZIANI et ALLEPUZ et al., 2007; BOLZONI and DE LEO, 2007; FELIZIANI et al., 2005; MEUWISSEN et al., 1999; MINTIENS et al., 2001al., 2005; MEUWISSEN et al., 1999; MINTIENS et al., 2001) show that most CSF infections ) show that most CSF infections persisted and spread in the areas with high pig density. Since pig density is an important persisted and spread in the areas with high pig density. Since pig density is an important risk factor associated with the occurrence and spread of CSF infection, it can explain risk factor associated with the occurrence and spread of CSF infection, it can explain the occurrence of primary outbreaks in that County after the introduction of the non-the occurrence of primary outbreaks in that County after the introduction of the non-vaccination strategy. On the other hand, there was a likelihood of CSF occurrence in this vaccination strategy. On the other hand, there was a likelihood of CSF occurrence in this area since the Vukovar-Sirmium County is located in the eastern part of Croatia bordered area since the Vukovar-Sirmium County is located in the eastern part of Croatia bordered by a country with no CSF free status. The occurrence of CSF outbreaks in this region by a country with no CSF free status. The occurrence of CSF outbreaks in this region with numerous small pig farms and the application of the control measures in the infected with numerous small pig farms and the application of the control measures in the infected and restricted areas caused important losses in pig production in Croatia. According and restricted areas caused important losses in pig production in Croatia. According

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to to TADIĆ TADIĆ et al. (2007)et al. (2007) the direct and indirect losses from CSF occurrence and control the direct and indirect losses from CSF occurrence and control consequences on the infected householders amounted to 1,583.98 kunas (287.1 USD) consequences on the infected householders amounted to 1,583.98 kunas (287.1 USD) per animal eradicated. At the beginning of the epidemic in the Vukovar-Sirmium County, per animal eradicated. At the beginning of the epidemic in the Vukovar-Sirmium County, 868 (5.41%) pigs from 55 (4.67%) households were euthanized (Table 3). According to 868 (5.41%) pigs from 55 (4.67%) households were euthanized (Table 3). According to PAVLAKPAVLAK et al. (2007a) et al. (2007a), there were 106 affected households and 3,917 euthanized pigs in , there were 106 affected households and 3,917 euthanized pigs in the Vukovar-Sirmium County in 2006 and 2007. 51.89% households were struck by CSF the Vukovar-Sirmium County in 2006 and 2007. 51.89% households were struck by CSF and 22.16% of pigs euthanized at the beginning of the epidemic, i.e. in the fi rst 14 days and 22.16% of pigs euthanized at the beginning of the epidemic, i.e. in the fi rst 14 days of the epidemic. Due to control measures including eradication of diseased and healthy of the epidemic. Due to control measures including eradication of diseased and healthy animals, occurrence of CSF epidemic causes great economic losses to the pork industry, animals, occurrence of CSF epidemic causes great economic losses to the pork industry, especially in agricultural areas. Therefore, in the Vukovar-Sirmium County, which is one especially in agricultural areas. Therefore, in the Vukovar-Sirmium County, which is one of the largest agricultural counties in Croatia, the CSF epidemic presented a great problem of the largest agricultural counties in Croatia, the CSF epidemic presented a great problem since 88.29% of all agricultural households are small pig farms. since 88.29% of all agricultural households are small pig farms.

Risk factors such as swill feeding and extensive farming, where contact with wild Risk factors such as swill feeding and extensive farming, where contact with wild boars is possible, have been estimated by odds ratio as a relative measure of association boars is possible, have been estimated by odds ratio as a relative measure of association ((THRUSFIELD, 1995; MARTIN et al., 1988THRUSFIELD, 1995; MARTIN et al., 1988). For this purpose was used a case-control study ). For this purpose was used a case-control study design including the data on pig farms on which pigs showed or did not show clinical design including the data on pig farms on which pigs showed or did not show clinical symptoms e. g. the disease was present or not. These two groups were considered in relation symptoms e. g. the disease was present or not. These two groups were considered in relation to the number of farms on which the pigs were swill-fed or not and kept extensively or to the number of farms on which the pigs were swill-fed or not and kept extensively or intensively. Out of the 1,178 pig farms observed, in 252 households (21.39%) pigs were intensively. Out of the 1,178 pig farms observed, in 252 households (21.39%) pigs were swill-fed. No association between swill feeding and disease development was found. Only swill-fed. No association between swill feeding and disease development was found. Only on two farms were diseased pigs fed with swill, while on 13 farms diseased pigs were on two farms were diseased pigs fed with swill, while on 13 farms diseased pigs were not swill-fed. Out of 1,178 observed pig farms, on 532 farms (45.16%) pigs were kept not swill-fed. Out of 1,178 observed pig farms, on 532 farms (45.16%) pigs were kept extensively. Extensive farming has been analyzed as a risk factor of exposure to contact extensively. Extensive farming has been analyzed as a risk factor of exposure to contact between domestic pigs and wild boars. Most of the pig farms which kept pigs extensively between domestic pigs and wild boars. Most of the pig farms which kept pigs extensively were located in Municipality 2 with a high pig density and where the fi rst outbreaks were located in Municipality 2 with a high pig density and where the fi rst outbreaks were noted. Consequently, in this area the highest number of pigs was covered by were noted. Consequently, in this area the highest number of pigs was covered by eradication control measures. Out of 41 observed households with euthanized pigs in this eradication control measures. Out of 41 observed households with euthanized pigs in this municipality, there were 17 households (41.46%) with extensive farming. Municipality municipality, there were 17 households (41.46%) with extensive farming. Municipality 1 is the area with the highest number of pigs in the Vukovar-Sirmium County (Table 2) 1 is the area with the highest number of pigs in the Vukovar-Sirmium County (Table 2) and also with a high number of households with extensive farming. But in this area only and also with a high number of households with extensive farming. But in this area only 0.53% of observed pigs were euthanized. On the other hand in Municipality 3 there is 0.53% of observed pigs were euthanized. On the other hand in Municipality 3 there is much more intensive than extensive farming and here the association between extensive much more intensive than extensive farming and here the association between extensive farming and disease was noted. The odds ratio in this area was 2.47. This means that in farming and disease was noted. The odds ratio in this area was 2.47. This means that in Municipality 3 the probability of the disease in extensive farming was about twice as high Municipality 3 the probability of the disease in extensive farming was about twice as high as the probability of the disease in intensive farming. The differences in the probability as the probability of the disease in intensive farming. The differences in the probability of exposure to the risk factor in Municipality 3 in comparison to other two municipalities of exposure to the risk factor in Municipality 3 in comparison to other two municipalities may be explained by the number of extensive and intensive farms. Although in all three may be explained by the number of extensive and intensive farms. Although in all three municipalities the number of farms affected by the disease was similar, there was a much municipalities the number of farms affected by the disease was similar, there was a much

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lower number of extensive than intensive farms in Municipality 3, unlike in the other two lower number of extensive than intensive farms in Municipality 3, unlike in the other two municipalities. municipalities.

According to the statistical data on CSF time distribution in Croatia, during the According to the statistical data on CSF time distribution in Croatia, during the CSF epidemic from July 2006 to April 2008, new CSF outbreaks (Var1) occurred 70 CSF epidemic from July 2006 to April 2008, new CSF outbreaks (Var1) occurred 70 times. During these 70 occurrences, a minimum of one and a maximum of eight new times. During these 70 occurrences, a minimum of one and a maximum of eight new CSF outbreaks were identifi ed (mean = 1.89, Confi dence 95% = 1.53-2.24). Out of all CSF outbreaks were identifi ed (mean = 1.89, Confi dence 95% = 1.53-2.24). Out of all observations of CSF outbreaks, in 60% of cases one new CSF outbreak was identifi ed and observations of CSF outbreaks, in 60% of cases one new CSF outbreak was identifi ed and in 21% two new CSF outbreaks were found per day. The highest number of outbreaks in 21% two new CSF outbreaks were found per day. The highest number of outbreaks identifi ed in one day was eight, which was observed on the 235identifi ed in one day was eight, which was observed on the 235thth day of the epidemic, day of the epidemic, or on day 23 according to the ordinal number of new outbreak occurrence. The most or on day 23 according to the ordinal number of new outbreak occurrence. The most frequent interval (80%) between two new outbreaks was within a 10-day period (mean frequent interval (80%) between two new outbreaks was within a 10-day period (mean 8.87 days, Confi dence 95% = 5.3-12.45 days). These data show a long-term CSF epidemic 8.87 days, Confi dence 95% = 5.3-12.45 days). These data show a long-term CSF epidemic with numerous outbreaks, mostly occurring separately, e. g. one outbreak per day. In the with numerous outbreaks, mostly occurring separately, e. g. one outbreak per day. In the fi rst two weeks, the epidemic spread in the area around the primary outbreak and during fi rst two weeks, the epidemic spread in the area around the primary outbreak and during this period a high number of euthanized pigs was observed. However after the primary this period a high number of euthanized pigs was observed. However after the primary outbreaks, the CSF epidemic spread into another 11 Counties of Croatia. On the same outbreaks, the CSF epidemic spread into another 11 Counties of Croatia. On the same day eight outbreaks were observed in three different Counties. The occurrence of new day eight outbreaks were observed in three different Counties. The occurrence of new CSF outbreaks in other parts of Croatia after the application of control measures in the CSF outbreaks in other parts of Croatia after the application of control measures in the area of the primary outbreaks could be explained by swill feeding and indirect contact area of the primary outbreaks could be explained by swill feeding and indirect contact with the primary or secondary outbreak areas, through transportation before the CSF was with the primary or secondary outbreak areas, through transportation before the CSF was diagnosed or before the restricted zone was established. The transport of infected animals diagnosed or before the restricted zone was established. The transport of infected animals in the infectious period before the disease was diagnosed, as well as illegal transport in the infectious period before the disease was diagnosed, as well as illegal transport of animals through the restricted zone could favor a long-term epidemic curve. This is of animals through the restricted zone could favor a long-term epidemic curve. This is in accordance with the CSF epidemic observed in the Netherlands where purchase of in accordance with the CSF epidemic observed in the Netherlands where purchase of infected animals and direct and indirect contact by transport vehicles and persons was infected animals and direct and indirect contact by transport vehicles and persons was defi ned as the main source of infection. The movement of pigs which are incubating the defi ned as the main source of infection. The movement of pigs which are incubating the disease or are persistently infected is the most common mode of CSF spread, especially disease or are persistently infected is the most common mode of CSF spread, especially at the beginning of outbreaks (at the beginning of outbreaks (ELBERS et al., 1999ELBERS et al., 1999). Similar data have been obtained in ). Similar data have been obtained in Germany where swill feeding was estimated as a primary source of CSF epidemic and Germany where swill feeding was estimated as a primary source of CSF epidemic and contacts with infected domestic pigs and wild boars were the main routes of the spread of contacts with infected domestic pigs and wild boars were the main routes of the spread of the CSF epidemic (the CSF epidemic (FRITZEMEIER et al., 2000; FRITZEMEIER et al., 2000; MOENNIG MOENNIG et al., 2003et al., 2003). ).

The CSF epidemic in Croatia in 2006-2008 spread to a large number of small pig farms The CSF epidemic in Croatia in 2006-2008 spread to a large number of small pig farms including three different counties at the same time and showed a long-term characteristic. including three different counties at the same time and showed a long-term characteristic. The long-term epidemic curve can be explained by the many small pig farms in a relative The long-term epidemic curve can be explained by the many small pig farms in a relative small area, where direct and indirect contacts were much more possible and presented the small area, where direct and indirect contacts were much more possible and presented the main routes of transmission. The long-term epidemic curve, as well as the high number main routes of transmission. The long-term epidemic curve, as well as the high number of euthanized pigs, led to a considerable decrease of pork production in the agricultural of euthanized pigs, led to a considerable decrease of pork production in the agricultural counties as well as in the whole country. counties as well as in the whole country.

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SAŽETAKSAŽETAKPrikazana je epidemiološka procjena pojave klasične svinjske kuge (KSK) u Republici Hrvatskoj od 2006. Prikazana je epidemiološka procjena pojave klasične svinjske kuge (KSK) u Republici Hrvatskoj od 2006.

do 2008. godine sa stajališta vremenskoga pojavljivanja. Analizirana je brojnost svinja prije pojave KSK u do 2008. godine sa stajališta vremenskoga pojavljivanja. Analizirana je brojnost svinja prije pojave KSK u Vukovarsko-srijemskoj županiji i utjecaj nekih rizičnih čimbenika kao što su hranjenje pomijama i mogućnost Vukovarsko-srijemskoj županiji i utjecaj nekih rizičnih čimbenika kao što su hranjenje pomijama i mogućnost dodira s divljim svinjama na pojavu i širenje KSK. Za analizu proizvodnje svinja u području Vukovarsko-dodira s divljim svinjama na pojavu i širenje KSK. Za analizu proizvodnje svinja u području Vukovarsko-srijemske županije uzeti su podatci o brojnosti gospodarstava koja drže svinje te podatci o broju svinja po srijemske županije uzeti su podatci o brojnosti gospodarstava koja drže svinje te podatci o broju svinja po gospodarstvima i po kategorijama. Podatci na temelju kojih se temeljila epidemiološka analiza pojave i širenja gospodarstvima i po kategorijama. Podatci na temelju kojih se temeljila epidemiološka analiza pojave i širenja KSK u razdoblju od 17. srpnja 2006. do 7. svibnja 2008. godine uključivali su točan datum pojave pojedinih KSK u razdoblju od 17. srpnja 2006. do 7. svibnja 2008. godine uključivali su točan datum pojave pojedinih žarišta, vrijeme između pojave pojedinih žarišta i vrijeme trajanja žarišta te broj zabilježenih žarišta u jednom žarišta, vrijeme između pojave pojedinih žarišta i vrijeme trajanja žarišta te broj zabilježenih žarišta u jednom danu. Prva žarišta KSK u Hrvatskoj zabilježena su na istoku zemlje u Vukovarsko-srijemskoj županiji u tri danu. Prva žarišta KSK u Hrvatskoj zabilježena su na istoku zemlje u Vukovarsko-srijemskoj županiji u tri općine, a tijekom vremena proširila se na 11 županija. Analizirajući rizične čimbenike na području Vukovarsko-općine, a tijekom vremena proširila se na 11 županija. Analizirajući rizične čimbenike na području Vukovarsko-srijemske županije, ustanovljeno je da su se u 532 (45,16%) od 1.178 promatranih gospodarstava svinje srijemske županije, ustanovljeno je da su se u 532 (45,16%) od 1.178 promatranih gospodarstava svinje držale ekstenzivno dok su se u 252 (21,39%) gospodarstva svinje hranile pomijama. Analizirajući vremensko držale ekstenzivno dok su se u 252 (21,39%) gospodarstva svinje hranile pomijama. Analizirajući vremensko pojavljivanje KSK u razdoblju od 2006. do 2008. godine, pojava novih žarišta KSK zabilježena je 70 puta i to pojavljivanje KSK u razdoblju od 2006. do 2008. godine, pojava novih žarišta KSK zabilježena je 70 puta i to u razdoblju od najmanje jednog i najviše 86. dana tijekom 621 dana trajanja epidemije. Broj žarišta zabilježen u razdoblju od najmanje jednog i najviše 86. dana tijekom 621 dana trajanja epidemije. Broj žarišta zabilježen u jednom danu najčešće je bio jedan. Najviše žarišta zabilježenih u jednom danu bilo je osam i to 235-og dana u jednom danu najčešće je bio jedan. Najviše žarišta zabilježenih u jednom danu bilo je osam i to 235-og dana od početka pojave epidemije. od početka pojave epidemije.

Ključne riječi:Ključne riječi: klasična svinjska kuga, Hrvatska, vremensko pojavljivanje, rizični čimbenik klasična svinjska kuga, Hrvatska, vremensko pojavljivanje, rizični čimbenik

Received: 19 June 2009Accepted: 29 October 2010

Vet. arhiv 81 (1), 51-66, 2011

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