Worm of the Week - Lymphatic Filariasis
Another installment from our Worm of the Week series, courtesy of student campaigners from Boston University! Today we feature:
Wuchereria bancrofti, Brugia malayai and Brugia timori
A physically and socially debilitating disease, lymphatic filariasis affects over 120 million people in 80 different countries. The thread-like parasitic filarial worms, Wuchereria bancrofti (causing most infections worldwide), and Brugia malayi and Brugia timori (primarily in Asia) lodge in the human lymphatic system. There, adult worms mate and produce millions of microscopic microfilariae that circulate in the person’s blood. Infection spreads by mosquito bites containing larval worms that travel to lymph and grow into adults which takes about six months. Adult worms can live 5 to 7 years.
Sometimes called elephantiasis due to the engorgement and thickening of skin, lymphatic filariasis is characterized by lymphedema, or fluid collection due to improper functioning of the lymph system resulting in swelling. Most infected individuals are asymptomatic and will never develop symptoms. In the severest cases, fluid accumulates in the legs, arms, breasts, and genitalia. Infected persons are at increased risk for bacterial infections in the skin and lymph system.
Microscopic identification of microfilariae in blood smear. Blood collection should be done at night.
Diethylcarbamazine (DEC) kills microfilaria and some of the adult worms; Ivermectin kills microfilaria.
Prevention and Control: The best way to avoid lymphatic filariasis is to avoid mosquito bites (sleep under mosquito net, use repellent, wear long sleeves and trousers). In 1997, the World Health Assembly called for the global elimination of lymphatic filariasis as a public health problem. The strategy for elimination is based on treating everyone eligible to take the medicine living in an affected community with a dose of two drugs: albendazole is used in conjunction with ivermectin (sub-Saharan Africa) and with DEC (elsewhere in world).