Mycoplasma hyopneumoniae (M.hyo)

The bacterium is endemic in most swine herds worldwide. Infection leads to a loss of the ciliated epithelium of the trachea and the bronchi, as well as to a modulation in the immune response of the respiratory tract.

Due to the reduced clearance and the impact on the local immune system M.hyo facilitates secondary infections with other respiratory pathogens

e.g. Pasteurella multocida. Clinical disease resulting from M.hyo and secondary infections is referred to as Enzootic Pneumonia (EP). Typical clinical signs are a chronic cough, reduced weight gain and an increased feed conversion ratio, mainly observed in finishing pigs. Only in severe and complicated cases an increase in mortality rate is noticeable. The onset and course of disease depends on multiple factors like the infectious dose and the virulence of the M.hyo strain, secondary infections, co-infections and environmental conditions, e.g. ventilation.

Clinical disease can be treated with antibiotics, which help to control the symptoms. However, lung lesions already present at start of treatment will lead to reduced performance. Prevention is believed to be the most effective method for decreasing the economic impact of the disease. Beside the improvement of housing and climate conditions, herd management (e.g. acclimatization of gilts, separation of age groups), hygiene and biosecurity, vaccination against Mycoplasma hyopneumoniae is an important tool for the control of Enzootic Pneumonia.