Brugia

Brugia is a genus of filarial nematodes that include species pathogenic to humans, most notably Brugia malayi and Brugia timori. Together with related filarial parasites, Brugia belongs to the family Onchocercidae within the superfamily Filarioidea. The principal human-infecting species are B. malayi and B. timori; Brugia pahangi is primarily a parasite of animals and human infections are rare.

Transmission occurs through mosquito bites. Vectors vary by region but commonly include species of Anopheles and Mansonia; the parasites are transmitted when a mosquito ingests microfilariae during a blood meal and later transmits infective larvae to a new host. In humans, adult worms reside in the lymphatic system, where they reproduce and release microfilariae into the bloodstream. Microfilariae typically exhibit nocturnal periodicity, increasing in peripheral blood at night to optimize uptake by nocturnal mosquito vectors.

Clinical features center on lymphatic filariasis. Chronic infection can cause lymphatic dysfunction, leading to limb swelling (lymphedema) and, in some cases, genital swelling and hydrocele. Acute inflammatory episodes can occur and may progress to elephantiasis in severe cases. Symptoms can develop years after initial infection.

Diagnosis relies on detecting microfilariae in blood samples or identifying circulating antigens. Microscopy of blood smears and concentration techniques are common; antigen-detection tests and molecular methods are also used.

Treatment includes antifilarial drugs such as diethylcarbamazine, often combined with ivermectin and/or albendazole. Doxycycline targets Wolbachia endosymbionts and can reduce transmission and worm fecundity. Public health efforts emphasize mass drug administration, vector control, and monitoring to eliminate brugian filariasis in endemic areas.