Filariasis

Infection with filarial nematodes, transmitted by biting flies and mosquitoes in tropical countries. Adult worms can live 10–15 years. Different species cause different disease, mostly skin/lymphatic with systemic features.

Filarial parasite	Disease
Onchocerca volvulus	Onchocerciasis (river blindness)
Wuchereria bancrofti	Bancroftian (lymphatic) filariasis
Brugia malayi / timori	Malayan (lymphatic) filariasis
Loa loa	Loiasis
Mansonella spp.	Mansonelliasis
Dirofilaria spp.	Dirofilariasis

Clinical features

• Onchocerciasis — itchy red spotty dermatitis (from microfilariae), which can ulcerate/secondary-infect; ocular disease → blindness.
• Bancroftian/Malayan — lymphatic disease → elephantiasis.
• Loiasis — itch similar to onchocerciasis; the adult worm may cross the eye.
• Mansonelliasis — often asymptomatic; chronic itchy dermatitis with lichenification.
• Dirofilariasis — humans are poor hosts; occasionally tender inflamed nodules.

Treatment (species-specific)

Disease	Treatment
Onchocerciasis	Ivermectin (drug of choice) ± nodulectomy
Lymphatic filariasis	Diethylcarbamazine (DEC) ± ivermectin (synergistic); doxycycline to kill Wolbachia; surgery for severe lymphoedema
Loiasis	DEC first-line — ivermectin contraindicated (risk of retinal haemorrhage and fatal encephalopathy); worm can be extracted from the eye
Mansonelliasis	DEC + mebendazole (M. perstans); ivermectin (M. streptocerca)
Dirofilariasis	Surgical removal/extraction of the worm

Prevention is by vector control and bite avoidance.