Mansonelliasis is the condition of infection by the nematode Mansonella. The disease exists in Africa and tropical Americas, spread by biting midges or blackflies. It is usually asymptomatic. Symptoms and signs Infections by Mansonella perstans, while often asymptomatic, can be associated with angioedema, pruritus, fever, headaches, arthralgias, and neurologic manifestations. Mansonella streptocerca can manifest on the skin via pruritus, papular eruptions and pigmentation changes. Mansonella ozzardi can cause symptoms that include arthralgias, headaches, fever, pulmonary symptoms, adenopathy, hepatomegaly, and pruritus. Eosinophilia is often prominent but do not occur in all cases of Mansonelliasis. M. perstans can also present with Calabar-like swellings, hives, and a condition known as Kampala, or Ugandan eye worm. This occurs when adult M. perstans invades the conjunctiva or periorbital connective tissues in the eye. M. perstans can also present with hydrocele in South America. However, it is often hard to distinguish between the symptoms of Mansonelliasis and other nematode infections endemic to the same areas. Causes Mansonelliasis is caused by nematodes (roundworms) in the Mansonella genus that reside in the skin or certain body cavities. The specific species are M. perstans, M. streptocerca and M. ozzardi. Vectors and life cycle During a blood meal, an infected midge (genus Culicoides) or blackfly (genus Simulium) introduces third-stage filarial larvae onto the skin of the human host, where they penetrate into the bite wound. They develop into adults that reside in body cavities, most commonly the peritoneal cavity or pleural cavity, but also occasionally in the pericardium (M. perstans), subcutaneous tissue (M. ozzardi) or dermis (M. steptocerca). In M. perstans, size range for female worms is 70 to 80 mm long and 120 μm in diameter, and the males measure approximately 45 mm by 60 μm. In M. steptocerca, the females measure approximately 27 mm long. Their diameter is 50 μm at the level of the vulva (anteriorly) and ovaries (near the posterior end), and up to 85 μm at the mid-body. Males measure 50 μm in diameter. In M. ozzardi, adult worms are rarely found in humans. The size range for females worms is 65 to 81 mm long and 0.21 to 0.25 mm in diameter but unknown for males. Adult worms recovered from experimentally infected Patas monkeys measured 24 to 28 mm long and 70 to 80 μm in diameter (males) and 32 to 62 mm long and .130 to .160 mm in diameter (females). Adults produce