Filarial infections are grouped into 3 categories of disease based on the location of disease: lymphatic, cutaneous, and body cavity
-Lymphatic filariasis is caused by three filarial nematodes: Wuchereria bancrofti (most common), Brugia malayi, and Brugia timori
-it is found mostly in South Asia and Africa
-Humans are infected by the bites of infected mosquitoes
-Larvae move to the lymphatics and lymph nodes, where they mature into adult worms, which produce large numbers of microfilariae
Symptoms & Signs
-Classical lesion: Lymphadenitis in the femoral area as a red, enlarged and tender lump spreading centrifugally down the lymphatic channels of the leg (centripetal spread in bacterial lymphangitis)
-recurrent bouts of “filarial fevers” lasting 2 to 3 weeks
-High fever, transient local edema, lymphatic inflammation – Acute adenolymphangitis (ADL)
-Elephantiasis, thickening of the subcutaneous tissues, brawny edema
-Conjunctivitis, headache, photophobia, vertigo, scrotal pain, orchitis, epididymitis, elephantiasis of breasts, vulva
Diagnosis
Detection of microfilariae in peripheral blood, hydrocele fluid; Periodicity determines the best time for blood collection; blood samples for Wuchereria and Brugia are only positive if drawn at night
Serology: Antigen assays, PCR
High-frequency ultrasound: can show motile adult worms
Treatment
Effective agents: Diethylcarbamazine (Drug of choice), Albendazole, Doxycycline, ivermectin
Diethylcarbamazine can cause hypersensitivity reaction with antigen liberation from dead microfilariae