Filariasis (Bancrofti)

The parasite
Bancrofti filariasis is a disease caused by threadlike round worms. Larvae enter the skin via the bite of an infected mosquito and settle in lymph nodes, principally in the groin and axilla.
Adult females release microfilaria into the blood to be available for another feeding mosquito and it is this normally causes fever.
The adult worm does not multiply in the human host, thus severity of disease depends on the number of infected bites received.

Distribution
Tropical areas of Africa, India (espeially in the south), other parts of South East Asia and Central and South America.

Clinical features
Over 300 million people worldwide are infected, but most cases are asymptomatic. Sometimes symptoms such as fever, lymphangitis and oedema develop.
Repeated and chronic infections can cause chronic lymphoedema of the limbs or genitalia which can be very disabling and usually irreversible.
Serious illness is rare in travellers.

Treatment is available for those with heavy infestation usually di-ethyl-carbamazime or sometimes ivermectin.

Prevention is through avoiding mosquito bites. There is no vaccine available.

Recommended for more information
'Lecture Notes in Tropical medicine' . Dion R. Bell. Blackwell Publications ISBN 0-632-02445-0 or ' Mansons textbook of Tropical Diseases' Ed.G.C.Cook WB Sanuders Company Ltd ISBN 0-7020-1764-7.