Medical Definition of Lymphatic filariasis

Reviewed on 3/29/2021

Lymphatic filariasis: A parasitic disease caused by the African eye worm, a microscopic thread-like worm. The adult worms can only live in the human lymph system.

Lymphatic filariasis affects over 120 million people in the tropics and sub-tropics of Asia, Africa, Western Pacific, and parts of Central and South America. The disease spreads from person to person by mosquito bites. When a mosquito bites a person who has lymphatic filariasis, microscopic worms circulating in the person's blood enter and infect the mosquito. If the infected mosquito bites another person, they can then get lymphatic filariasis. The microscopic worms pass from the mosquito through the skin, and travel to the lymph vessels. In the lymph vessels they grow into adults. An adult worm lives for about 7 years. The adult worms mate and release millions of microscopic worms into the blood. Once a person has the worms in their blood, when a mosquito bites, the mosquito can transmit the disease to yet another person.

A person needs many mosquito bites over several months to years to get lymphatic filariasis. People living or staying for a long time in tropical or sub-tropical areas where the disease is common are at the greatest risk for infection. Short-term tourists have a very low risk. An infection will show up on a blood test.

At first, most people don't know they have lymphatic filariasis. They usually don't feel any symptoms until after the adult worms die. The disease usually is not life threatening, but it can permanently damage the lymph system and kidneys. Because the lymph system does not work right, fluid collects and causes swelling in the arms, breasts legs, and, for men, the genital area. The name for this swelling is lymphedema. The entire leg, arm, or genital area may swell to several times its normal size. Also, the swelling and the decreased function of the lymph system make it difficult for the body to fight germs and infections. A person with the disease tends to have more bacterial infections in the skin and lymph system. This causes hardening and thickening of the skin, which is called elephantiasis.

Lymphatic filariasis is a leading cause of permanent and long-term disability worldwide. People with the disease can suffer pain, disfigurement, and sexual disability. Communities frequently shun women and men disfigured by the disease. Many women with visible signs of the disease will never marry, or their spouses and families will reject them. Affected people frequently are unable to work because of their disability. This hurts their families and their communities. Poor sanitation and rapid growth in tropical and subtropical areas of the world, where the disease is common, has created more places for mosquitoes to breed and has led to more people becoming infected.

Prevention includes giving entire communities medicine that kills the microscopic worms and controlling mosquitoes. Avoiding mosquito bites is another form of prevention. The mosquitoes that carry the microscopic worms usually bite between the hours of dusk and dawn. If you live in an area with lymphatic filariasis:

  • Sleep under a mosquito net.
  • Use mosquito repellant on your exposed skin between dusk and dawn.
  • Take a yearly dose of medicine that kills the worms circulating in the blood. The medicine will kill all of the microscopic worms in the blood and some of the adult worms. It does not kill all of them.

To treat lymphatic filariasis a person with adult worms should take a yearly dose of medicine that kills the microscopic worms circulating in your blood. While this does not kill the adult worms, it does prevent the person from giving the disease to someone else. Even after the adult worms die, a person can have swelling of the arms, legs, breasts, or genitals. To keep the swelling from getting worse:

  • Carefully wash the swollen area with soap and water every day.
  • Use anti-bacterial cream on any wounds. This stops bacterial infections and keeps the swelling from worsening.
  • Elevate and exercise the swollen arm or leg to move the fluid and improve the lymph flow.



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