Mansonella ozzardi is found only in the New World, occurring in South America and certain foci in the Caribbean. The adult worms are embedded iii visceral adipose tissue. Although they are usually regarded as nonpathogenic, fever, headache, lymphadenitis, and erythematous irritant skin rashes have been reported in association with their presence. Cold extremities, the result of peripheral vasoconstriction caused by a postulated filarial toxin, have been reported. The microfilariae show no particular periodicity and are about twice the size of perstans and have a different caudal morphology. Simulium amazonicum has been implicated as the vector, and midges of the genus Culicoides have also been suggested.
