The Filarial Genome Network
Biology and Epidemiology
Mansonella perstans is widely distributed throughout central Africa. In certain locations in Zaire, Nigeria, Ghana, Sierra Leone, Ivory Coast, Zambia, and Uganda extremely high proportions of the inhabitants show signs of infection. It is also found in the new world in Venezuela, Trinidad, Guyana, Surinam, northern Argentina and Amazonia.
M. perstans is transmitted to humans by the midges Culicoides grahami and C. austeni. Once inside the body the infective larvae move to serous cavities (pleural and peritoneal), mesentery, peri-renal spaces, retroperitoneal spaces or the pericardium and mature into adults. Because of their habits the adults are rarely seen but they have been found to be cylindrical in shape with lengths and diameters of 4-5 cm x 0.06 mm in males and 7.8 cm x 0.12 mm in the females. The mated adults produce microfilariae which are unsheathed with lengths and diameters of 200 x 4.5 micrometers. They possess the power of elongation and contraction so they can vary in measurement and form. The microfilariae of M. perstans are smaller than those of W. bancrofti and the caudal end is blunt with a terminal nucleus (see picture below taken from Peters and Gilles 1991). They are nonperiodic and circulate in the blood in equal amounts through out the day and night. The microfilariae can also often be found in the cerebrospinal fluids.
The vast majority of infections with M. perstans are asymptomatic. Some individuals do show symptomless eosinophilia, pleuritis, abdominal pain, and transient skin swellings. However, to date most studies have not found any serious conditions connected with perstanian infection.
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last modified 01/01/96