Outbreaks In Domestic Pigs Research Articles

Investigating the role of free-ranging wild boar (Sus scrofa) in the re-emergence of enzootic pneumonia in domestic pig herds: a pathological, prevalence and risk-factor study.

Enzootic pneumonia (EP) caused by Mycoplasma hyopneumoniae has a significant economic impact on domestic pig production. A control program carried out from 1999 to 2003 successfully reduced disease occurrence in domestic pigs in Switzerland, but recurrent outbreaks suggested a potential role of free-ranging wild boar (Sus scrofa) as a source of re-infection. Since little is known on the epidemiology of EP in wild boar populations, our aims were: (1) to estimate the prevalence of M. hyopneumoniae infections in wild boar in Switzerland; (2) to identify risk factors for infection in wild boar; and (3) to assess whether infection in wild boar is associated with the same gross and microscopic lesions typical of EP in domestic pigs. Nasal swabs, bronchial swabs and lung samples were collected from 978 wild boar from five study areas in Switzerland between October 2011 and May 2013. Swabs were analyzed by qualitative real time PCR and a histopathological study was conducted on lung tissues. Risk factor analysis was performed using multivariable logistic regression modeling. Overall prevalence in nasal swabs was 26.2% (95% CI 23.3–29.3%) but significant geographical differences were observed. Wild boar density, occurrence of EP outbreaks in domestic pigs and young age were identified as risk factors for infection. There was a significant association between infection and lesions consistent with EP in domestic pigs. We have concluded that M. hyopneumoniae is widespread in the Swiss wild boar population, that the same risk factors for infection of domestic pigs also act as risk factors for infection of wild boar, and that infected wild boar develop lesions similar to those found in domestic pigs. However, based on our data and the outbreak pattern in domestic pigs, we propose that spillover from domestic pigs to wild boar is more likely than transmission from wild boar to pigs.

Modelling the spread of Swine Vesicular Disease Virus and Vesicular Stomatitis Virus in an area of livestock units without any control measures and measurement of consequential impact resulting from an assumed introduction into one livestock farm

EFSA Supporting PublicationsVolume 9, Issue 5 285E External scientific reportOpen Access Modelling the spread of Swine Vesicular Disease Virus and Vesicular Stomatitis Virus in an area of livestock units without any control measures and measurement of consequential impact resulting from an assumed introduction into one livestock farm Dr. Dirk Eisinger, Dr. Dirk Eisinger Dr. Dirk EisingerSearch for more papers by this author Dr. Dirk Eisinger, Dr. Dirk Eisinger Dr. Dirk EisingerSearch for more papers by this author First published: 21 May 2012 https://doi.org/10.2903/sp.efsa.2012.EN-285 This external report is not produced by EFSA. It is published to help keep the public informed of developments related to EFSA's scientific work. EFSA reserves its rights, view and position as regards the issues addressed and conclusions reached in the present document, without prejudice to the rights of the authors. Published date: 21 May 2012 Question number: EFSA-Q-2011-01135 AboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat References Backer, J.A., Brouwer, H., van Schaik, G., van Roermind, H.J.W., 2011. Using mortality data for early detection of Classical Swine Fever in The Netherlands. Prev. Vet. Med. 99, 38– 47. Backer, J.A., Hagenaars, T.J., van Roermund, H.J.W., de Jong, M.C.M., 2009. Modelling the effectiveness and risks of vaccination strategies to control classical swine fever epidemics. Journal of the Royal Society Interface 6, 849– 861. Bates, T.W., Thurmond, M.C., Carpenter, T.E., 2003. Description of an epidemic simulation model for use in evaluating strategies to control an outbreak of foot-and-mouth disease. Am. J. Vet. Res. 64, 195– 204. EFSA, 2012. Scientific Opinion on Swine Vesicular Disease and Vesicular Stomatitis. The EFSA Journal 10, 2631. Elbers, A.R.W., Stegeman, A., Moser, H., Ekker, H.M., Smak, J.A., Pluimers, F.H., 1999. The classical swine fever epidemic 1997–1998 in the Netherlands: descriptive epidemiology. Prev. Vet. Med. 42, 157– 184. Garner, M.G., Beckett, S.D., 2005. Modelling the spread of foot-and-mouth disease in Australia. Aust Vet J 83, 758– 766. Grimm, V., Berger, U., Bastiansen, F., Eliassen, S., Ginot, V., Giske, J., Goss-Custard, J., Grand, T., Heinz, S., Huse, G., Huth, A., Jepsen, J.U., Jørgensen, C., Mooij, W.M., Müller, B., Pe'er, G., Piou, C., Railsback, S.F., Robbins, A.M., Robbins, M.M., Rossmanith, E., Rüger, N., Strand, E., Souissi, S., Stillman, R.A., Vabø, R., Visser, U., DeAngelis, D.L., 2006. A standard protocol for describing individual-based and agent-based models. Ecol. Modell. 198, 115– 126. Grimm, V., Berger, U., DeAngelis, D.L., Polhill, J.G., Giske, J., Railsback, S.F., 2010. The ODD protocol: a review and first update. Ecol. Modell. 221, 2760– 2768. Harvey, N., Reeves, A., Schoenbaum, M.A., Zagmutt-Vergara, F.J., Dubé, C., Hill, A.E., Corso, B.A., McNab, W.B., Cartwright, C.I., Salman, M.D., 2007. The North American Animal Disease Spread Model: A simulation model to assist decision making in evaluating animal disease incursions. Prev. Vet. Med. 82, 176– 197. Ribbens, S., Dewulf, J., Koenen, F., Laevens, H., de Kruif, A., 2004. Transmission of classical swine fever. A review. Veterinary Quarterly 26, 146– 155. Staubach, C., Teuffert, J., Thulke, H.-H., 1997. Risk analysis and local spread mechanisms of classical swine fever. Epidémiol. santé anim. 31–32, 6.12.1– 3. Stegeman, A.J., Elbers, A.R.W., Bouma, A., de Jong, M.C.M., 2002. Rate of inter-herd transmission of classical swine fever virus by different types of contact during the 1997–8 epidemic in The Netherlands. Epidemiol. Infect. 128, 285– 291. Thulke, H.-H., Eisinger, D., Beer, M., 2011. The role of movement restrictions and pre-emptive destruction in the emergency control strategy against CSF outbreaks in domestic pigs. Prev. Vet. Med. 99, 28– 37. Volume9, Issue5May 2012285E ReferencesRelatedInformation

Challenge of Pigs with Classical Swine Fever Viruses after C-Strain Vaccination Reveals Remarkably Rapid Protection and Insights into Early Immunity

Pre-emptive culling is becoming increasingly questioned as a means of controlling animal diseases, including classical swine fever (CSF). This has prompted discussions on the use of emergency vaccination to control future CSF outbreaks in domestic pigs. Despite a long history of safe use in endemic areas, there is a paucity of data on aspects important to emergency strategies, such as how rapidly CSFV vaccines would protect against transmission, and if this protection is equivalent for all viral genotypes, including highly divergent genotype 3 strains. To evaluate these questions, pigs were vaccinated with the Riemser® C-strain vaccine at 1, 3 and 5 days prior to challenge with genotype 2.1 and 3.3 challenge strains. The vaccine provided equivalent protection against clinical disease caused by for the two challenge strains and, as expected, protection was complete at 5 days post-vaccination. Substantial protection was achieved after 3 days, which was sufficient to prevent transmission of the 3.3 strain to animals in direct contact. Even by one day post-vaccination approximately half the animals were partially protected, and were able to control the infection, indicating that a reduction of the infectious potential is achieved very rapidly after vaccination. There was a close temporal correlation between T cell IFN-γ responses and protection. Interestingly, compared to responses of animals challenged 5 days after vaccination, challenge of animals 3 or 1 days post-vaccination resulted in impaired vaccine-induced T cell responses. This, together with the failure to detect a T cell IFN-γ response in unprotected and unvaccinated animals, indicates that virulent CSFV can inhibit the potent antiviral host defences primed by C-strain in the early period post vaccination.

The role of movement restrictions and pre-emptive destruction in the emergency control strategy against CSF outbreaks in domestic pigs

Classical swine fever (CSF) outbreaks in domestic pig herds lead to the implementation of standard control measures according to legislative regulations. Ideal outbreak control entails the swift and efficient culling of all pigs on premises detected positive for CSF virus. Often all pig holdings around the detected cases are pre-emptively destroyed to exclude transmission into the neighbourhood. In addition to these measures, zones are defined in which surveillance and protection measures are intensified to prevent further distant disease spread. In particular, all movements are prohibited within standstill areas. Standstill also excludes the transport of fattened pigs to slaughter. Historical outbreaks provide evidence of the success of this control strategy. However, the extent to which the individual strategy elements contribute to this success is unknown. Therefore, we applied a spatially and temporally explicit epidemic model to the problem. Its rule-based formulation is tailored to a one-by-one model implementation of existing control concepts. Using a comparative model analysis the individual contributions of single measures to overall control success were revealed. From the results of the model we concluded that movement restrictions had the dominant impact on strategy performance suggesting a reversal of the current conceptual thinking. Additional measures such as pre-emptive culling only became relevant under imperfect compliance with movement restrictions. The importance of movement restrictions for the overall control success illustrates the need for explicit consideration of this measure when contingency strategies are being amended (e.g. emergency vaccination) and associated risks assessed.

Porcine brucellosis (Brucella suis)

Porcine brucellosis (Brucella suis)

Epidemiological risk factors of Aujeszky’s disease in wild boars (Sus scrofa) and domestic pigs in Spain

An Aujeszky’s disease (AD) control and eradication campaign started in Spain in 1995, and as a result, AD virus (ADV) seroprevalences have notably diminished in Spanish domestic pig herds, but eradication has not yet been achieved. Since the presence of ADV in Spanish wild boar populations can impede schemes to eradicate ADV in domestic pig, we conducted analyses of risk factors and investigated associations between the patterns of ADV seroprevalence at the municipal level in the wild boar and the domestic pig, respectively, in south-central Spain. There was a clear influence of individual factors on the risk of wild boar to test positive to ADV. Concerning the domestic pig, higher ADV seroprevalences were observed with increasing numbers of pigs per farm. Indoor pig farms showed higher seroprevalences than open-air farms. Our results show that, at least at the study scale, the level of ADV seroprevalence in domestic pig farms is not influenced by the level of ADV seroprevalence in the coexisting wild boar populations. Also, there was no influence of domestic pigs ADV seroprevalence on the risk of wild boars to test seropositive. Finally, there was no evidence for a statistical association between ADV seroprevalence levels in wild boar and domestic pig at the municipal level in the study region. These findings are of interest for both veterinary and public health authorities. Nevertheless, more effort is needed in order to elucidate the nature of particular ADV outbreaks in domestic pigs in the study region due to possible contacts with wild boars, which will probably require a molecular approach.

CP7_E2alf: A safe and efficient marker vaccine strain for oral immunisation of wild boar against Classical swine fever virus (CSFV)

Wild boar are an important reservoir of Classical swine fever virus (CSFV) in several European countries, where most of the primary outbreaks in domestic pigs are directly related to the endemic disease situation in the wild boar population. Oral immunisation has been introduced as an additional control measure to accelerate CSF eradication in wild boar in Germany since 1993. Immunisation with an oral bait vaccine based on the conventionally attenuated live vaccine strain “C” proved to be safe and effective, but does not allow differentiation between infected and vaccinated animals. Therefore, we examined the vaccine efficacy of the recently constructed chimeric pestivirus CP7_E2alf, whose coding sequences for the major envelope protein E2 of BVDV strain CP7 are replaced by E2 of the CSFV strain Alfort187 [Reimann I, Depner K, Trapp S, Beer M. An avirulent chimeric pestivirus with altered cell tropism protects pigs against lethal infection with classical swine fever virus. Virology 2004;322(1):143–57]. Following oral immunisation of wild boar, CP7_E2alf proved to be completely avirulent. Furthermore, all vaccinees were fully protected from clinical disease after a highly virulent CSFV challenge infection. The immunised animals seroconverted within 3 weeks after vaccination for CSFV E2-specific and CSFV neutralising antibodies, whereas prior to challenge infection no antibodies against CSFV E rns were detected with an appropriate CSFV-specific marker ELISA test. Thus, the BVDV backbone of CP7_E2alf enables serological and genetic differentiation from wild type CSFV infection. In conclusion, CP7_E2alf represents the first efficient and safe marker vaccine candidate for oral immunisation of wild boar against CSFV.

Phylogenetic analysis of classical swine fever virus (CSFV) field isolates from outbreaks in South and Central America

To date, there is little information concerning the epidemiological situation of classical swine fever (CSF) in the Americas. Besides summarizing the available data, genotyping of isolates from outbreaks in domestic pigs in several countries of South and Central America was performed. For this, a 190 base fragment of the E2 envelope glycoprotein gene was used. European strains and isolates, and historical isolates from the United States (US) were included for comparison. In contrast to the situation in most parts of Europe, where group 2 isolates predominate, it was found that all the isolates from the American continent analyzed belonged to group 1 and were further resolved into three subgroups. The Cuban isolates clustered in subgroup 1.2, whereas the isolates from Honduras and Guatemala clustered in subgroup 1.3. The remaining isolates from Argentina, Brazil, Colombia and Mexico generated four poorly resolved clusters in subgroup 1.1, together with the vaccine strains, with historical European and US isolates, and with a recent Russian isolate. While the vaccine strains and the historical European isolates formed a relatively distinct cluster, one of the US isolates clustered together with the Mexican, and another one with Colombian isolates. Historically, CSF (hog cholera) was observed almost simultaneously in the US and in Europe in the first half of the 19th century, and its origin remains a matter of discussion. Our results showed that the US isolates are closely related to isolates from South America, while appearance of isolates in Cuba on one hand and in Honduras and Guatemala on the other hand, seems to have been due to unrelated events. This allows to speculate that at least in the American continent, CSF virus may have appeared independently in several regions, and spreading may have been a secondary effect.

Molecular epidemiology of classical swine fever in Italy

To gain an insight into the molecular epidemiology of classical swine fever (CSF) in Italy, virus isolates originating from outbreaks that occurred between 1985 and 2000 in wild boar or in domestic pigs in mainland Italy and in Sardinia were analysed by genetic typing. For this, a fragment (190 nucleotides) of the E2 glycoprotein gene was sequenced and phylogenetic analyses were performed, including older Italian isolates and isolates from recent outbreaks in Europe for comparison. The results show that in mainland Italy, several independent epidemiological events occurred in the last decade. In the north of the country, viruses of genotype 2.2 have persisted in wild boar, causing sporadic outbreaks in domestic pigs. In contrast, viruses of subgroups 2.1 and 2.3 appeared only intermittently in different regions of the mainland. In 1997, classical swine fever virus (CSFV) isolates belonging to the subgroup 2.1 and genetically and epidemiologically related to the Dutch isolate in Venhorst, affected domestic pigs exclusively. The isolates of subgroup 2.3, derived from wild boar as well as from domestic pigs were closely related to isolates from Germany and Poland. In Sardinia, CSF is an endemic in wild boar and affects domestic pigs also. Genetic typing showed that viruses of subgroups 1.1 and 2.3 have been present, the last ones being unrelated to the mainland viruses of the same subgroup. Due to the large quantities of pig and wild boar meat imported in some parts of Italy, it cannot be established if these viruses were always present in either the mainland or Sardinia, or if they represent recent introductions.

Genetic typing of classical swine fever virus isolates from the territory of the Czech Republic.

Epizootiological studies based on genetic typing were performed using 14 isolates from outbreaks of classical swine fever (CSF) in domestic pigs and wild boar in the Czech Republic which occurred between 1991 and 1998. They were compared with Austrian, Slovakian, Hungarian, Polish and German isolates. The aim of this study was to characterise the CSF virus isolates and find out the possible relationships between the outbreaks in domestic pigs and wild boar, and to map the spread of the virus in the Czech Republic. For this, fragments of the 5' nontranslated region (5' NTR) and of the E2 glycoprotein gene were sequenced and used for genetic typing. The analysis of both fragments of the genome showed that the Czech isolates belong to two CSF subgroups within group 2, namely to subgroups 2.2 and 2.3. A close relation was found with Austrian isolates from 1992 and 1994, belonging to subgroup 2.2. The isolates in subgroup 2.3 formed a very homogeneous group, although they originated from different regions of the country. They seem identical to two Slovakian isolates from 1998, and differed from Hungarian isolates from 1992. Epizootiological links became evident when the epidemiological data were compared.

Epidemiology of classical swine fever in Germany in the 1990s.

In Germany, 424 outbreaks of CSF in domestic pigs and a great number of cases in wild boar were recorded between 1990 and 1998. Most of the federal states ('Bundesländer') were affected. Epidemiological data from field investigations combined with genetic typing allowed to distinguish seven unrelated epidemics and a number of sporadic outbreaks in domestic pigs. Detailed epidemiological data was available for 327 outbreaks. It was found that 28% of these were primary outbreaks. Most of them were due to indirect or direct contact to wild boar infected with CSF virus or swill feeding. Infected wild boar remain the main risk for domestic pigs. The most frequent sources of infection in secondary or follow up outbreaks were the trade with infected pigs, neighbourhood contacts to infected farms and other contacts via contaminated persons and vehicles, respectively. An increased risk of virus transmission from infected herds to neighbourhood farms was observed up to a radius of approximately 500m. More than two thirds of the infected herds were discovered due to clinical signs. About 20% were identified by epidemiological tracing on and back. These were scrutinised because contacts to infected herds were evident. In conclusion, tracing of contact herds and clinical examination combined with carefully targeted virological testing of suspicious animals is likely to be the most important measure to immediately uncover secondary outbreaks. Obligatory serological screening in the surveillance and the restriction zones do not seem to be efficient measures to detect follow-up outbreaks.

Serological and immunohistochemical study of African swine fever in wild boar in Spain

A serological and immunohistochemical study of African swine fever was carried out in wild boar killed in seven municipalities in the north of the province of Cordoba during two hunting...

Influenza virus A/swine — Outbreaks in domestic pigs and antibody findings in human sera

In the last years, the occurrence of influenza viruses A/H1N1 (Hsw1N1) in pig stocks of different countries has been increasingly reported. In general, the isolated viruses were related to the influenza virus A/New Jersey/8/76 H1N1 (Hsw1N1). Human infections were not reported in these outbreaks. Since March 1981, very limited influenza outbreaks in several pig stocks of the GDR with high morbidity and very low lethality have been observed. The illness took an uncomplicated path and generally subsided after 3 days. Some of the virus isolates were examined and typed as influenza virus A/swine/Potsdam/81/H1N1 (Hsw1N1). By serological examinations of convalescent pigs the aetiologic importance of the isolates was confirmed. Infection of the contact persons by the influenza virus A/swine/Potsdam/81 is to be regarded as likely according to the serological results.