Mansonelliasis

Mansonelliasis (or mansonellosis) 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.

Mansonelliasis, in the form of M. ozzardi, was first documented in 1897.

Mansonelliasis is found in Latin America from the Yucatán peninsula to northern Argentina, in the Caribbean, and in Africa from Senegal to Kenya and south to Angola and Zimbabwe. M. ozzardi is found only in the New World, M. steptocerca is found only in the Congo basin, and M. perstans is found in both the previously described areas of Africa and Latin America. Prevalence rates vary from a few percent to as much as 90% in areas like Trinidad, Guyana and Colombia.

Infection is more common and has a higher microfilarial dose with age, though studies have found microfilarial dose not to be correlated with symptoms. In parts of rural South America, men have been found more susceptible than women, possibly due to more outdoors work by males as children, and possibly due to cooking fires serving as deterrents to vectors for women who perform more domestic duties. One study in central Africa found M. perstans to be a much more common cause of filariasis symptoms compared to Loa loa and Wuchereria bancrofti.

Since most Mansonelliasis is asymptomatic, it has been considered a relatively minor filarial disease, and has a very low, if any, mortality, though there is little data to base estimates on.

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 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.

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.

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).

...
Wikipedia