A parasitic infection caused by the tissue-dwelling filarial nematode worm Wuchereria bancrofti; a wide range of mosquitoes transmit the infection. When the worm is mature, it inhabits lymph nodes and produces sheathed microfilarial larvae that circulate in the peripheral blood.
Clinical Presentation:
- Infection with the adult worms produces painless subcutaneous nodules that are usually less than 2 cm in diameter, typically over bony prominences.
- Symptoms depend on where the microfilariae migrate to, and vary accordingly. They include: pruritus, papular dermatitis, dermal atrophy and depigmentation or hyperreactive skin disease (Sowda), keratitis, iritis, chorioretinitis, optic atrophy and eventually blindness, orchitis, hydrocele, chyluria, elephantiasis, pulmonary eosinophilia, cough, wheezing, and splenomegaly.
Diagnosis:
- Peripheral blood smear taken between 11pm and 1am or after provocation using diethylcarbamazine (DEC).
- Filarial antigen test.
- Eosinophilia, and specific antiflarial IgG and IgE antibodies.
Treatment:
- DEC which must be obtained directly from the CDC.
- Alternatively Doxycycline. Both drugs are effective against both macro and micro-filaria.
Bottom Line:
One billion people globally are at risk for infection with filaria. 120 million already have the infection. Suspect the infection in patients that have been to Africa, Asia, especially India, Western pacific, Haiti, the Dominican Republic, Guyana and Brazil.
University of Maryland Section of Global Emergency Health
Author: Walid Hammad, MD
References
James AG Whitworth. Filariasis. Medicine. 2005;33:61
