African Swine Fever in a Bulgarian Backyard Farm—A Case Report

Zani, Laura; Dietze, Klaas; Dimova, Zlatina; Forth, Jan Hendrik; Denev, Daniel; Depner, Klaus; Alexandrov, Tsviatko

doi:10.3390/vetsci6040094

Cited by 47 publications

(80 citation statements)

References 22 publications

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“…Therefore, the general mortality rate may not exceed normal levels and the initially low ASF induced mortality can easily be overlooked, particularly in larger farms. It could be shown that ASF virus might circulate in a herd for nearly a month before it causes a marked increase in mortality [ 15 , 17 , 18 ]. Under such conditions, enhanced surveillance targeting sick and dead animals, independently from the mortality rate, would be the only practical option for early ASF detection.…”

Section: Discussionmentioning

confidence: 99%

“…Experimental findings as well as field studies have proven a low transmissibility of ASFV, which may delay the virus spread inside a pen and between pens [ 15 , 16 , 18 ]. The calculated period from infection until onset of infectiousness was around 10 days within a pen and around 13 days between pigs in different pens in a study by Guinat et al [ 15 ].…”

Section: Discussionmentioning

confidence: 99%

“…For the estimation of HRP and the reconstruction of the spreading pathways within the farm, the information obtained from the farm records and interviews with farm staff, clinical and post-mortem findings and laboratory results were evaluated. If clinical data were interpreted, an infection cycle from infection until death of ten days was assumed [ 17 , 18 , 22 ]. For laboratory findings showing positive RT-PCR and immunoperoxidase test (IPT) results after a period of up to 10 days, it was assumed that might have passed from infection until death of the sampled pigs (C. Gallardo, personal communication (European Union reference laboratory (INIA-CISA), Valdeolmos, Madrid, Spain).…”

Section: Case Descriptionmentioning

confidence: 99%

“…It is very important to detect infected farms as early as possible after ASF virus introduction to avoid further spread and to minimize the losses to the pig sector and reduce governmental costs associated with outbreak eradication [ 14 ]. Animal experiments as well as field observations have shown that a low to moderate transmissibility of ASF virus between pigs is leading to a slow spread of the disease within a farm [ 10 , 15 , 16 , 17 , 18 , 19 ]. Therefore, the inadvertent introduction of the virus may remain unnoticed by the farmer or the veterinarian for extended time.…”

Section: Introductionmentioning

confidence: 99%

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African Swine Fever in Two Large Commercial Pig Farms in LATVIA—Estimation of the High Risk Period and Virus Spread within the Farm

Lamberga

Oļševskis

Seržants³

et al. 2020

Veterinary Sciences

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African swine fever (ASF) was first detected in Latvia in wild boar at the Eastern border in June 2014. Since then ASF has continued to spread in wild boar populations covering almost whole territory of the country. Sporadic outbreaks occurred at the same time in domestic pig holdings located in wild boar infected areas. Here we present the results of the epidemiological investigation in two large commercial farms. Several parameters were analyzed to determine the high risk period (HRP) and to investigate the ASF virus spread within the farm. Clinical data, mortality rates and laboratory results proved to be good indicators for estimating the HRP. The measures for early disease detection, particularly the enhanced passive surveillance that is targeting dead and sick pigs, were analyzed and discussed. Enhanced passive surveillance proved to be a key element to detect ASF at an early stage. The study also showed that ASF virus might spread slowly within a large farm depending mainly on direct contacts between pigs and the level of internal biosecurity. Findings suggest improvements in outbreak prevention, control measures and may contribute to a better understanding of ASF spreading patterns within large pig herds. Culling of all pigs in large commercial farms could be reconsidered under certain conditions.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Case Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

African Swine Fever in Two Large Commercial Pig Farms in LATVIA—Estimation of the High Risk Period and Virus Spread within the Farm

Lamberga

Oļševskis

Seržants³

et al. 2020

Veterinary Sciences

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“…African swine fever, tenacity, virus survival, wild boar carcasses and disinfection, the risk for further spread of the disease can be minimized (Zani et al, 2019). If ASF occurs in wild boar, the situation is much more complex.…”

Section: Introductionmentioning

confidence: 99%

African swine fever virus survival in buried wild boar carcasses

Zani

Masiulis

Bušauskas³

et al. 2020

Transbound Emerg Dis

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Since the first introduction of African swine fever (ASF) into the European wild boar population in 1957, the question of virus survival in carcasses of animals that succumbed to the disease has been discussed. The causative African swine fever virus (ASFV) is known to be very stable in the environment. Thus, carcasses of infected wild boar could play a major role as ASFV reservoir and thereby help to locally maintain and spread the disease in wild boar populations. To minimize this risk, removal of wild boar carcasses in ASF affected areas is regarded to be crucial for effective disease control. If removal is not feasible, carcasses are usually disposed by burial on the spot to avoid direct contact of wild boar to the infection source. In this study, carcasses of ASFV infected wild boar buried in Lithuania at different time points and locations have been excavated and retested for the presence of infectious ASFV by in vitro assays and for viral genome by qPCR. Soil samples potentially contaminated by body fluids have been additionally tested for viral genome. In seventeen out of twenty burial sites, samples of excavated carcasses were positive for ASFV genome. However, in none of the carcass samples ASFV could be isolated. On seven sites soil samples contained ASF viral DNA. These results unexpectedly negate the long‐term persistence of infectious ASFV in wild boar carcasses independent from the burial time. In this context, sensitivity of ASFV isolation from carcass samples versus susceptibility of animals and doses needed for oral inoculation has to be further investigated. Furthermore, research is required to consider alternative ASF infection sources and drivers in the infection cycle among wild boar.

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The course of African swine fever in Romanian backyard holdings – A case report

Ardelean¹,

Globig

Năvălici³

et al. 2021

Veterinary Medicine & Sci

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African swine fever (ASF) was diagnosed for the first time in Romania in a backyard holding in Satu-Mare County in July 2017. Since then, more than 3800 outbreaks occurred in the entire country. Disease control strategies in the backyard sector rely almost exclusively on reactive measures implemented upon appearance of clinical signs and laboratory confirmation of ASF. In our descriptive study, infection course and outbreak investigation data of 56 affected backyard holdings in Satu-Mare County has been investigated. Early disease detection based on clinical signs appeared to be efficient. In the majority of outbreaks, ASF was detected within the first 2 weeks after the estimated virus introduction. A clinical phase of 2-8 days was observed before pigs either succumbed to the disease or control measures were implemented on affected farms. A moderate on-farm transmissibility of ASF virus between pigs was observed.Four clusters of outbreaks were identified indicating virus perpetuation and transmission from farm to farm. To suspend infection chains, rapid intervention by isolating affected farms combined with effective biosecurity measures is required. However, due to the backyard peculiarities, quick and effective implementation of control measures has shown to be rather difficult.

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African Swine Fever in a Bulgarian Backyard Farm—A Case Report

Abstract: African swine fever (ASF) is one of the most threatening diseases for the pig farming sector worldwide. As an effective vaccine is lacking, strict application of control measures

Cited by 47 publications

References 22 publications

African Swine Fever in Two Large Commercial Pig Farms in LATVIA—Estimation of the High Risk Period and Virus Spread within the Farm

African Swine Fever in Two Large Commercial Pig Farms in LATVIA—Estimation of the High Risk Period and Virus Spread within the Farm

African swine fever virus survival in buried wild boar carcasses

The course of African swine fever in Romanian backyard holdings – A case report

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