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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.

Batista Linhares M, Belloy L, Origgi FC, Lechner I, Segner H, Ryser-Degiorgis MP - PLoS ONE (2015)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Centre for Fish and Wildlife Health (FIWI), Vetsuisse Faculty, University of Bern, Bern, Switzerland.

ABSTRACT
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.

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Related in: MedlinePlus

Map of Switzerland depicting the location of the study areas.The five study areas (units A-E) are indicated by shades of grey. Black lines correspond to canton borders, and blue areas are main lakes. The origin of wild boar (Sus scrofa) samples and their real-time PCR results are indicated by colored dots: Samples negative for Mycoplasma hyopneumoniae are green and positive samples are red.
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pone.0119060.g002: Map of Switzerland depicting the location of the study areas.The five study areas (units A-E) are indicated by shades of grey. Black lines correspond to canton borders, and blue areas are main lakes. The origin of wild boar (Sus scrofa) samples and their real-time PCR results are indicated by colored dots: Samples negative for Mycoplasma hyopneumoniae are green and positive samples are red.

Mentions: The location of the five units within the country and their characteristics are indicated in Fig. 2 and Table 1, respectively. Unit A largely corresponds to the canton of Geneva, on the border of France. It is characterized by one of the highest wild boar densities in Europe (from 10.6–10.0 individuals/km2 [19]) and the highest WBDens in this study. Unit B lies in the heart of the Jura Mountains and covers the cantons of Jura, Basel-Land, a great part of Solothurn and smaller regions of Aargau and Bern. It borders France and Germany. Unit C lies in the center of the Swiss Plateau and covers the canton of Freiburg and a large part of Bern. Its WBDens is relatively low but unevenly distributed within the area (most wild boar being present in the north-west of the region) and the OPDens is the highest of all units. Unit D corresponds to the canton of Thurgovia and borders Germany. It has a hunting bag comparable to unit A but moderate WBDens and OPDens. Unit E corresponds to the canton of Tessin at the border with Italy. Its hunting bag is the highest of all Swiss cantons (over 1000 wild boar in each of the two last reported yearly hunting bags) and its wild boar population is therefore considered as very large despite a moderate WBDens.


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.

Batista Linhares M, Belloy L, Origgi FC, Lechner I, Segner H, Ryser-Degiorgis MP - PLoS ONE (2015)

Map of Switzerland depicting the location of the study areas.The five study areas (units A-E) are indicated by shades of grey. Black lines correspond to canton borders, and blue areas are main lakes. The origin of wild boar (Sus scrofa) samples and their real-time PCR results are indicated by colored dots: Samples negative for Mycoplasma hyopneumoniae are green and positive samples are red.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4352045&req=5

pone.0119060.g002: Map of Switzerland depicting the location of the study areas.The five study areas (units A-E) are indicated by shades of grey. Black lines correspond to canton borders, and blue areas are main lakes. The origin of wild boar (Sus scrofa) samples and their real-time PCR results are indicated by colored dots: Samples negative for Mycoplasma hyopneumoniae are green and positive samples are red.
Mentions: The location of the five units within the country and their characteristics are indicated in Fig. 2 and Table 1, respectively. Unit A largely corresponds to the canton of Geneva, on the border of France. It is characterized by one of the highest wild boar densities in Europe (from 10.6–10.0 individuals/km2 [19]) and the highest WBDens in this study. Unit B lies in the heart of the Jura Mountains and covers the cantons of Jura, Basel-Land, a great part of Solothurn and smaller regions of Aargau and Bern. It borders France and Germany. Unit C lies in the center of the Swiss Plateau and covers the canton of Freiburg and a large part of Bern. Its WBDens is relatively low but unevenly distributed within the area (most wild boar being present in the north-west of the region) and the OPDens is the highest of all units. Unit D corresponds to the canton of Thurgovia and borders Germany. It has a hunting bag comparable to unit A but moderate WBDens and OPDens. Unit E corresponds to the canton of Tessin at the border with Italy. Its hunting bag is the highest of all Swiss cantons (over 1000 wild boar in each of the two last reported yearly hunting bags) and its wild boar population is therefore considered as very large despite a moderate WBDens.

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Centre for Fish and Wildlife Health (FIWI), Vetsuisse Faculty, University of Bern, Bern, Switzerland.

ABSTRACT
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.

Show MeSH
Related in: MedlinePlus