More than 1.2 billion people around the world are threatened by lymphatic filariasis (LF), one of thirteen neglected tropical diseases. This debilitating disease affects 120 million people in 83 countries, including Brazil, India, and much of Central Africa. Caused by thread-like parasitic worms that attack the lymphatic system, LF is usually contracted during childhood, often before age five, but the disease manifests itself in adulthood.
More than 40 million people—the poorest of the poor—are seriously incapacitated by the swelling of the limbs, breasts, and genitals caused by LF. Next to mental illness, LF is the leading cause of disability in the world. Annual economic losses are estimated at $4 billion. LF is one of only six infectious diseases considered eliminable by the World Health Assembly, which has set a timetable for worldwide elimination by 2020.
LF is not generally a fatal disease, and therefore tends to receive less attention than killers such as AIDS, tuberculosis, and malaria. However, the overt manifestations of LF—such as elephantiasis and male hydrocele—maim, disfigure, and socially isolate people for a lifetime. Filarial infection also renders tissues especially susceptible to injuries and a host of normally innocuous bacteria and fungi.
Even young infected children likely suffer some kidney and lung impairment due to thousands of circulating filarial worms in the blood, though they often do not yet display the overt manifestations of the disease. In people with lymphedema or elephantiasis, acute inflammatory attacks of the lymph nodes and vessels can be so severe they generate second-degree burns and require emergency treatment. In some cases, complications from infections compounded by a person’s LF-compromised lymphatic system can be fatal.