Serological, pathological and polymerase chain reaction studies on Mycoplasma hyopneumoniae infection in the wild boar.

There are evidences that wild boar and domestic pig populations share the vulnerability to certain pathogens and, in consequence, the risk of pathogen transmission. Based on serological evidences, it is known that Mycoplasma hyopneumoniae (Mhyo) is able to infect the wild boar. However, if this infection causes lesions and disease in this species is still unknown. The objectives of the present study were to assess the seroprevalence to Mhyo, as well as the rates of detection of Mhyo (by nested polymerase chain reaction, nPCR) in upper and lower respiratory tract of the wild boar. Moreover, presence of enzootic pneumonia (EP)-like gross and microscopic lesions in these animals was also assessed. Antibodies against Mhyo were detected in 92 out of 428 (21%) serum samples tested. Moreover, Mhyo DNA was detected by nPCR in 17 out of 85 (20%) nasal swabs and in 12 out of 156 (8%) lung samples. No gross EP-like lesions were observed in any of the studied pigs. Besides, presence of EP-like microscopic lung lesions was observed in 18 out of 63 (29%) animals. Mhyo DNA was detected at lung level in 2 out of these 18 (11%) animals. Presence of EP-like microscopic lesions was significantly related (p<0.05) with Mhyo detection at nasal swab swab but not (p>0.05) with its detection in lung samples; such lesions were also linked (p<0.05) with presence of Metastrongylus spp.-like parasite structures. Results of the present study confirm that Mhyo is able to infect and might be able to cause EP-like microscopic lesions in wild boar but, apparently, with a subclinical impact.