Lungworms

Lungworms are parasitic worms that inhabit the lungs or airways of mammals, birds, and, in some cases, humans. The term covers two main groups: nematodes (lung nematodes) and flukes (lung trematodes). They are found worldwide and can cause disease in domestic animals, livestock, wildlife, and occasionally people.

Nematode lungworms commonly affect dogs, cats, and ruminants. In dogs, Angiostrongylus vasorum is a well-known lungworm; in cats, Aelurostrongylus abstrusus is typical. Dictyocaulus species infect cattle, sheep, goats, and horses. Other nematodes may inhabit the lungs of various hosts. Clinical signs range from mild coughing to severe pneumonia, depending on the species and parasite burden.

Trematode lungworms, or lung flukes, include Paragonimus species such as Paragonimus westermani in humans and other mammals, and Paragonimus kellicotti in parts of North America. Their life cycle usually requires a freshwater snail as the first intermediate host and a crustacean as the second; humans or other definitive hosts become infected by consuming raw or undercooked intermediate or paratenic hosts. Infections typically affect the lungs and may cause chest pain, coughing, and coughing up blood.

Life cycles generally involve larval stages migrating from the digestive tract or other sites to the lungs, where adults reside and egg production occurs. Diagnosis combines imaging, examination of sputum or feces for larvae or eggs (when feasible), and, in some cases, serology or PCR. Treatments rely on anthelmintics such as benzimidazoles or macrocyclic lactones, with species-appropriate choices. Prevention focuses on reducing exposure to intermediate hosts and avoiding ingestion of raw mollusks or crustaceans. Some lungworms have zoonotic potential, and human infections, though rare, have been reported.