Wuchereria

Wuchereria is a genus of threadlike parasitic nematodes in the family Filarioidea. The species most commonly associated with human disease is Wuchereria bancrofti, which causes bancroftian lymphatic filariasis. Other filarial species in the broader group infect animals, and human disease caused by Wuchereria outside bancrofti is rare.

Wuchereria bancrofti is transmitted by mosquitoes, including species of Culex, Anopheles, and Aedes, depending on geographic region. In the human host, adult worms reside in the lymphatic vessels and produce microfilariae that circulate in the peripheral blood, typically with nocturnal periodicity. Mosquitoes ingest microfilariae during a blood meal; within the vector, they develop to infective larvae (L3) and are transmitted to a new human host during subsequent feeding. In the human, L3 migrate to lymphatics, mature into adults, and release microfilariae, continuing the life cycle and potentially causing lymphatic pathology.

Clinical features range from asymptomatic to symptomatic disease. Acute manifestations include fever and lymphadenitis, while chronic infection can lead to lymphatic obstruction with limb and genital swelling, hydrocele, and, in severe cases, elephantiasis. Recurrent infections and secondary bacterial complications can worsen outcomes.

Diagnosis relies on detecting microfilariae in blood samples, usually collected at night due to the parasites’ nocturnal periodicity, or on tests that detect circulating filarial antigens. Molecular methods (such as PCR) can confirm species. Imaging and clinical examination aid assessment of lymphatic damage.

Treatment and control involve antifilarial regimens such as diethylcarbamazine (DEC), or combinations including ivermectin and/or albendazole to reduce microfilariae and transmission. Mass drug administration and vector control are central to public health efforts to eliminate lymphatic filariasis in endemic regions.