Mansonella ozzardi causes 1 of 3 forms of human mansonelliasis, along with Mansonella perstans and Mansonella streptocerca. Mansonella ozzardi is transmitted by Culicoides biting midges in the Caribbean and Simulium blackflies in mainland South America. This infection is more prevalent in men. Farmers and fisherman are at higher risk.

Mansonella ozzardi infection occurs when a midge takes a blood meal from a human, which allows the transfer of filarial larvae to the bite wound. The filarial larvae develop into adults in subcutaneous tissue, mesenteries, and peritoneum, where they produce microfilariae. When a midge takes a blood meal from an infected host, the microfilariae are ingested and develop into larvae in the midge's gastrointestinal tract.

Infection by M. ozzardi is usually asymptomatic. If symptomatic, initial symptoms may include fever, arthralgias, headache, dizziness, coldness in the legs, adenopathy, and hepatomegaly. Cutaneous symptoms include pruritus, angioedema, and hyperpigmentation. Ocular lesions, primarily nummular keratitis, may occur. Peripheral eosinophilia is a characteristic finding.