infectious diseases
Overview of Filarial Nematode Infections
Introduction
Filarioidea are a superfamily of threadlike, parasitic worms, with numerous families, genus, and species. Their definitive hosts are vertebrates, but only a few filarial species infect humans. Threadlike adult filarial worms reside in lymphatic or subcutaneous tissues. Gravid females produce live offspring (microfilariae) that circulate in blood or migrate through tissues. When ingested by a suitable bloodsucking insect (mosquitoes or flies), microfilariae develop into infective larvae that are inoculated or deposited in the skin of the next host during the insect bite. Life cycles of all filarial worms are similar except for the site of infection. The major filarial diseases below can be grouped based on the location of adult worms. (See also Approach to Parasitic Infections .) Subcutaneous filariasisincludes Loiasis caused by Onchocerciasis (River Blindness) (river blindness) caused by Lymphatic filariasisincludes Bancroftian and Brugian Lymphatic Filariasis caused by Other types of filariasisinclude Mansonellosis caused by Dirofilariasis caused by Some specialty laboratories have screening serologic tests for filarial infection (includingWuchereria,Brugia,Onchocerca, andMansonellainfections). The tests are sensitive but cannot identify the specific filarial infection or distinguish active from remote infection. This distinction is less important in symptomatic travelers, but limits the usefulness of the tests in people from endemic areas. 