Respiratory disease associated with migrating Ascaris larvae in a beef calf

A group of 4-month-old beef calves were examined for clinical respiratory disease with labored breathing, coughing, and fevers of over 104 °F. Necropsy of one of the calves revealed lungs that were not collapsed but had red mottled appearance on cut surface. Assessment of lung tissue by bacterial culture and PCR did not reveal bovine bacterial or viral respiratory pathogens. Histopathology of affected tissues and lymph nodes revealed larval ascarid nematodes. In combination with phylogenetic analysis, amplification and sequencing of ITS1 was used to identify the larvae as Ascaris.