Habronemosis

Abstract

Equid habronemosis is a widespread parasitic disease caused by the dioecious nematodes Habronema microstoma, Habronema muscae, and Draschia megastoma (Spirurida, Habronematidae). These parasites live as both larvae and adults in the stomach of domestic and wild equids (i.e., horses, donkeys, mules, and zebras), while as larvae they live on the skin and occasionally on other sites, such as ocular and genital mucosa and lung parenchyma. Their life cycle requires an intermediate host, represented by dung-inhabiting secretophagous or hematophagous muscid flies. Habronemosis causes mild to severe clinical symptoms in affected animals, depending on the parasite’s stage of development stage and on localization. Larvae and adults living in the stomach cause gastric habronemosis, while larvae on the skin cause cutaneous habronemosis (known as “summer sores”). When larvae infect other sites, such as the ocular and genital mucosa of horses, they cause mucocutaneous habronemosis. Habronemosis causes severe economic losses, which mainly regard sportive horses, because their performance is impaired and the infection is unaesthetic. Clinical diagnosis of habronemosis is quite difficult, because the symptoms may overlap those of other diseases. Molecular diagnosis is a useful tool for both clinicians and epidemiologists. Macrocyclic lactones are effective against clinical habronemosis, while disease prevention relies on control of flies.