How does M hyo cause disease

M. hyo - the primary causal agent
M. hyo is the causal agent of enzootic pneumonia (EP) of pigs. EP is a chronic disease of the respiratory system characterised by a high infection rate in the herd (morbidity), although mortality is usually low.   In its uncomplicated form, symptoms include an unproductive cough which may be associated with a slight fever and reduced feed intake.

Enzootic pneumonia is not a disease of individual animals; instead it is a herd disease which affects large numbers of animals. Non-infected herds become infected by introduction of EP-positive pigs. Infection is also possible via airborne transmission which has been proven to occur over a distance of up to 3.2 kilometres as well as via equipment and by other means.

Enzootic pneumonia starts when the pathogen, M. hyo colonises the cilia in the respiratory tract. Cilia are small, hairlike processes found in the bronchioles of the lungs. With their rhythmic motions, the cilia keep the respiratory tract clear of dirt and bacteria, thus constituting a vital cleansing function for the lungs.

Once attached to the tips of the cilia, mycoplasma destroys the cilia. This impairs the lung's immune system, causing secondary bacteria to adhere to the epithelium and secondary infection to set in.