Lymphatic filariasis (LF), also known as “elephantiasis”, is one of the world's most debilitating parasitic diseases. Transmitted by mosquitoes, LF is a principal cause of disability in over eighty endemic countries and territories. More than one billion people live at risk of infection, and 120 million individuals already suffer from the debilitating disease.

The parasite responsible for the damage caused by LF is a long, thread-like worm. Most infections are caused by the species Wuchereria bancrofti, followed by Brugia malayi in Asia, and a small number are caused by Brugia timori in parts of Indonesia. As larvae, the “microfilariae” circulate in the blood of an infected person and are taken up by mosquitoes during blood meals. The microfilariae then develop inside the mosquito to become infective-stage larvae, which can infect another person during the mosquito’s subsequent blood meal. Once inside the human body, the microfilariae develop into adult worms which reside in lymphatic vessels. These adult worms can measure up to 10 centimeters in length but only approximately 0.25 millimeters in diameter (with the female worms almost twice the size of the males). As adults, the female worms can release over 10,000 microfilariae each day!

LF causes inflammation of the lymph nodes and/or lymph vessels. Over time, this inflammation combined with the calcification of dying adult worms can lead to blockages of lymph vessels. Due to the reduced flow of lymph fluid, an accumulation can occur and cause swelling, most commonly of the scrotal sac (“hydrocele”), but also of the legs, female genitals, arms and/or breasts (“lymphoedema”). Repeated bacterial and/or fungal infections in the affected areas cause a thickening and hardening of the skin, resulting in “elephantiasis”, which is painful and disfiguring; it can often lead to ostracism from the patient’s community.

The good news is that the spread of LF can be stopped. By reaching at-risk communities once per year with two donated or inexpensive drugs for approximately 6 consecutive years, transmission of the disease from an infected community member to his or her neighbors and family members can be prevented.

For more information about LF and the diverse group of partners working to eliminate it, please visit the website of the Global Alliance to Eliminate LF.