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Occurrence and Severity of Lung Lesions in Slaughter Pigs Vaccinated against Mycoplasma hyopneumoniae with Different Strategies

11 February 2014

New research from Germany reveals that Mycoplasma hyopneumoniae is still a major problem, causing signs of enzootic pneumonia despite the widely applied vaccination.

Different vaccination strategies against Mycoplasma hyopneumoniae have been adopted worldwide. Writing in Preventative Veterinary Medicine, Sonja Hillen from Justus-Liebig-University in Giessen, Germany, and co-authors state that reports from the field indicate varying levels of protection among currently available vaccines.

The goal of their study was to compare the efficacies of three widespread commercial vaccination strategies against M. hyopneumoniae under field conditions. 20 farms were included. Fourteen farms used different single-dose vaccines; vaccine 1 (V1), eight herds; vaccine 2 (V2), six herds; another six farms (V3) used a two-dose vaccination strategy.

Gross lesions of 854 lungs and histopathology from 140 lungs were quantified, and a quantitative PCR was applied to detect M. hyopneumoniae and porcine circovirus 2 (PCV2) DNA in lung tissue (n=140). In addition, porcine reproductive and respiratory disease virus (PRRSV), swine influenza virus (SIV), Actinobacillus pleuropneumoniae, Haemophilus parasuis and Pasteurella multocida were tested by qualitative PCR.

Fifty-three per cent of lungs were positive for M. hyopneumoniae. 55.9 per cent of lungs showed macroscopic enzootic pneumonia (EP)-like lesions.

Lung lesion scores (P<0.001) and M. hyopneumoniae-loads (P<0.008) differed significantly among the vaccination groups, with the most severe cases and highest amounts occurring in V1.

Histological alterations differed (P<0.001) between V1 and V3.

Lung lesion scores and histopathological changes were significantly correlated, with prevalence and load of M. hyopneumoniae indicating that the applied diagnostic tools are valuable in confirming the prevalence and severity of M. hyopneumoniae infections.

Comparing different vaccination strategies against M. hyopneumoniae indicates varying levels of protection. M. hyopneumoniae is still a major problem despite the widely applied vaccination.


Hillen S., S. von Berg, K. Köhler, M. Reinacher, H. Willems and G. Reiner. 2014. Occurrence and severity of lung lesions in slaughter pigs vaccinated against Mycoplasma hyopneumoniae with different strategies. Preventive Veterinary Medicine. 113(4):580–588.

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February 2014

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