A review of some aspects of the epidemiology, diagnosis, and control of Mycoplasma hyopneumoniae infections

Mycoplasma hyopneumoniae (MH), one of the most important swine pathogens, is distributed world wide. Alone, MH is relatively benign,but associated with other pathogens, which is almost always the case in field situations, it may cause serious losses. The combination of porcine reproductive and respiratory syndrome virus and MH is particularly important in respiratory problems of grow-finish pigs. Different strains of MH exist, but their significance remains to be evaluated. Transmission occurs mainly by direct contact and aerosol. Cranioventral lesions of pneumonia are suggestive of MH, but are not pathognomonic. The use of modern production technologies has coincided, to a certain extent, with an upsurge of MH-associated problems. Antimicrobials are more efficacious when used for prevention rather than treatment. Optimal timing for vaccination depends on the age at which pigs will come in contact with the organism and their level of maternal immunity when vaccinated. It is possible to produce MH-negative pigs from infected herds and to eradicate the organism without total depopulation.