The parasitic disease covered is caused by nematodes of the superfamily Filarioidea. Although this group includes lymphatic filariasis (elephantiasis), onchocerciasis (river blindness), loiasis (Calabar swelling) and forms of mansonellosis, the term filariasis is usually used to describe lymphatic filariasis caused by Wuchereria bancrofti, Brugia malayi or B. timori.
Lymphatic filariasis is transmitted through the bite of infected mosquitoes, which introduce larval forms of the nematode during a blood meal.
Nature of the disease
Lymphatic filariasis is a chronic parasitic disease in which adult filaria inhabit the lymphatic vessels, discharging microfilaria into the bloodstream. Typical manifestations in symptomatic cases include filarial fever, lymphadenitis and retrograde lymphangitis, followed by chronic manifestations such as lymphoedema, hydrocele, chyluria, tropical pulmonary eosinophilic syndrome and, in rare instances, renal damage.
Lymphatic filariasis occurs throughout sub-Saharan Africa and in much of south-east Asia, in the Pacific islands and in smaller foci in South America.
Risk for travellers
Generally low, unless travel involves extensive exposure to vectors in countries or areas at risk.
Avoid exposure to the bites of mosquitoes in countries or areas at risk.