Filariasis is a neglected tropical disease, a parasitic disease caused by microscopic, thread-like worms. Neglected tropical diseases (including filariasis) are prevalent among mostly impoverished (poor) communities located in tropical areas. Traditionally, these diseases have not received as much attention as other diseases.
The reservoir of these filarial worms is the human. They are considered human parasites; animal reservoirs are of minor importance or absent altogether. (Vectors, transmission, and life cycle will be discussed further on the following pages.)
The lymphatic form of filariasis is caused by infection with Wuchereria or Brugia. Over 120 million people in 72 countries worldwide are affected by lymphatic filariasis, according to the CDC.3
Over 863 million people worldwide are at risk of infection and require preventive chemotherapy treatments.4
The disease causes disability but is rarely fatal. However, secondary untreated bacterial infection may result in death.
Infection is not seen in the United States (except for the US territory of American Samoa), although cases may present due to travel or living in these endemic countries.
Filarial Agents and Associated Worldwide Geographic Distribution
| Filarial Agent | General Distribution |
Wuchereria bancrofti
| Tropics and subtropics of Asia, Africa, the Western/South Pacific, and sometimes in South America and Caribbean countries. |
Brugia malayi
| Southeast Asia (Philippines, Indonesia, Malaysia, Vietnam, S. Korea), India |
Brugia timori
| Lesser Sunda Archipelago Islands; (Brugia timori has been found on only two Timorian islands) |
Loa loa
| West Central Africa (South of the Sahara) |
Onchocerca volvulus
| South-Saharan Africa, Yemen, Central and South America |
Mansonella ozzardi
| Central and South America, Carribean |
Mansonella streptocerca
| Tropical sub-Saharan Africa |
Mansonella perstans
| Sub-Saharan Africa, Central and South America, Caribbean |
