Lymphatic Filariasis

• Lymphatic filariasis [lim-FA-tick fil-uh-RY-uh-sis] is a disease of the tropics. It is caused by infection with any of several round, thread-like parasitic worms. The most common is infection with a parasite that lives in the lymph system. This is called lymphatic filariasis.
• The parasite is spread from person to person by infected mosquitoes.
• Long-term exposure and repeated infections can cause severe damage to the lymph system and serious, debilitating complications.
• Prevention centers on controlling mosquito populations in communities and avoiding mosquito bites.
What is lymphatic filariasis?
Filariasis is an infection with any of several round, thread-like parasitic worms. The most common type of filariasis is infection with a parasitic worm that lives in the human lymph system. This is called lymphatic filariasis.
What is the infectious agent that causes lymphatic filariasis?
Filariasis is caused by three types of parasitic worms: Wuchereria bancrofti, Brugia malayi, and Brugia timori.
Where is lymphatic filariasis found?
Lymphatic filariasis is a disease of the tropics. Wuchereria bancrofti, the most common filariasis parasite, is found in Africa, India, Southeast Asia, the Pacific islands, the Caribbean, and South America. The Brugia malayi and Brugia timori parasites are found in Southeast Asia.
How is lymphatic filariasis spread?
Filariasis is spread from infected persons to uninfected persons by mosquitoes. Adult worms live in an infected person's lymph vessels. The females release large numbers of very small worm larvae, which circulate in an infected person's bloodstream. When the person is bitten by a mosquito, the mosquito can ingest the larvae. These develop in the mosquito and can then be spread to other people via mosquito bites. After a bite, the larvae pass through the skin, travel to the lymph vessels, and develop into adults, which live about 7 years. Then the cycle begins again.
What are the signs and symptoms of lymphatic filariasis?
Most of the signs and symptoms of filariasis are caused as a consequence of the adult worms living in the lymph system. Tissue damage caused by the worms restricts the normal flow of lymph fluid. This results in swelling, scarring, and infections. The legs and groin are most often affected.
How soon after exposure do symptoms appear?
Symptoms can appear 5-18 months after a mosquito bite.
How is lymphatic filariasis diagnosed?
Filariasis larvae can sometimes be detected in blood.
Who is at risk for lymphatic filariasis?
Those most at risk are people who live in or stay for a long time in tropical areas where the disease is common. Short-term tourists rarely get filariasis. Getting an infection with symptoms usually requires several mosquito bites over a long period of time.
What complications can result from lymphatic filariasis?
Lymphatic filariasis is rarely fatal, but it can cause recurring infections, fevers, severe inflammation of the lymph system, and a lung condition called tropical pulmonary eosinophilia (TPE). In about 5% of infected persons, a condition called elephantiasis causes the legs to become grossly swollen. This can lead to severe disfigurement, decreased mobility, and long-term disability. Testicular hydrocele is a disfiguring enlargement of the scrotum.
What is the treatment for lymphatic filariasis?
Treatment consists of: 1) medicine to kill circulating larvae and adult worms, 2) soap and water and skin care to prevent secondary infections, and 3) elevation, exercises, and, in some cases, pressure bandages to reduce swelling.
How common is lymphatic filariasis?
At least 120 million people in 73 countries worldwide are estimated to be infected with filariasis parasites. The most widespread is Wuchereria bancrofti, which affects about 100 million people in Africa, India, Southeast Asia, the Pacific islands, South America, and the Caribbean. The Brugia malayi and Brugia timori parasites affect about 12 million people in Southeast Asia.
Is lymphatic filariasis an emerging infectious disease?
Yes. Lymphatic filariasis is among the world's leading causes of permanent and long-term disability. The number of infected persons is increasing worldwide, due in large part to unchecked urbanization in many areas where the parasite is common.
How can lymphatic filariasis be prevented?
There is no vaccine for filariasis. Prevention centers on mass treatment with anti-filariasis drugs to prevent ingestion of larvae by mosquitoes, public health action to control mosquitoes, and individual action to avoid mosquito bites. To avoid being bitten by mosquitoes:
• If possible, stay inside between dusk and dark. This is when mosquitoes are most active in their search for food.
• When outside, wear long pants and long-sleeved shirts.
• Spray exposed skin with an insect repellent