Cattle are infected with lungworm through eating grass which is contaminated with infective larvae passed out in the dung of other infected animals. Mild, damp conditions favour the survival of these larvae on the pasture.  The present warm conditions with rainfall favour this situation.

Lungworm is a parasitic infection of the respiratory tract in cattle, which can cause severe disease outbreaks with coughing and respiratory distress. Death can occur in heavy infestations. Other signs can include weight loss, and reduced milk yield in dairy cows.  Animals that are exposed to lungworms usually develop immunity to re-infection. However, a lack of exposure in young cattle can result in clinical disease in older cattle. In order to maintain immunity, further exposure to lungworm is important.  Disease in older animals is being increasingly diagnosed in AFBI both in those that have not previously been exposed, or in those whose immunity has diminished due to not having been re-exposed and so vigilance is advised.