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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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Detected target groups of Mycoplasma hyopneumonia types in the five study areas.Data refer to PCR-positive nasal swabs from wild boar. Study areas: units A-E. Dark blue: ABC/REP type. Light blue: ABC-only type. Grey: REP-only type.
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pone.0119060.g004: Detected target groups of Mycoplasma hyopneumonia types in the five study areas.Data refer to PCR-positive nasal swabs from wild boar. Study areas: units A-E. Dark blue: ABC/REP type. Light blue: ABC-only type. Grey: REP-only type.

Mentions: Both PCR targets (ABC and REP) were amplified in about half (52.4%, N = 117/223) of the real-time PCR-positive samples of nasal swabs. From all positive nasal swabs, 30.4% (N = 68/223) was detected only by the REP target and 17.0% (N = 38/223) only by the ABC target. All three Mhyop types (ABC/REP, ABC only, and REP only) were present in samples from each geographical unit but in different proportions. While in the northern wild boar population (units A-D) both targets were usually detected within a sample (59.5%, N = 115/193), in unit E the majority of the PCR-positive wild boar reacted only to the ABC target (Fig. 4, p-values < 0.0001).


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)

Detected target groups of Mycoplasma hyopneumonia types in the five study areas.Data refer to PCR-positive nasal swabs from wild boar. Study areas: units A-E. Dark blue: ABC/REP type. Light blue: ABC-only type. Grey: REP-only type.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0119060.g004: Detected target groups of Mycoplasma hyopneumonia types in the five study areas.Data refer to PCR-positive nasal swabs from wild boar. Study areas: units A-E. Dark blue: ABC/REP type. Light blue: ABC-only type. Grey: REP-only type.
Mentions: Both PCR targets (ABC and REP) were amplified in about half (52.4%, N = 117/223) of the real-time PCR-positive samples of nasal swabs. From all positive nasal swabs, 30.4% (N = 68/223) was detected only by the REP target and 17.0% (N = 38/223) only by the ABC target. All three Mhyop types (ABC/REP, ABC only, and REP only) were present in samples from each geographical unit but in different proportions. While in the northern wild boar population (units A-D) both targets were usually detected within a sample (59.5%, N = 115/193), in unit E the majority of the PCR-positive wild boar reacted only to the ABC target (Fig. 4, p-values < 0.0001).

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