Filariasis

Filariasis is a parasitic disease caused by a microscopic worm. It is transmitted by mosquitos from person to person. It is commonly referred to as Elephantiasis.

The worm lives in the lymphatic vessels of the body. The lymph system of the body transfers fluid from tissues into the venous system and is very important to prevent limb oedema (swelling). It is also important in the fight against infections. The worms can cause a blockage to the lymph vessels which causes dfluid accumulation. This disfigurement is responsible for the term elephantiasis.

Female mosquitos release microfilariae which circulate in the peripheral blood, and these are ingested by other mosquitos to infect other people. This is termed person to person transmission through the bite of a particular mosquito. In the lymph vessels the worms grow into adults. An adult worm can live for 4-6 years and release many thousands of microfilariae which can affect other people.

There are 2 main species of microscopic worms that cause lymphatic disease in humans. These are: Wushereria bancrofti and Brugia malayi.

The disease was once a major problem worldwide. Elimination programs have now limited its geographic presence to a few regions. The disease currently affects over 120 million people in 72 countries. It is found in Africa (Egypt and sub-Saharan Africa), Asia (India, southeast Asia). some islands in the Pacific, Brazil, Guyana and the Dominican Republic.

The disease is responsible for significant disability in many cases.

Travellers are at low risk of acquiring the disease. Those visiting or living in areas of risk for extended periods of time are at much greater risk, particularly if exposed to large numbers of potentially infected mosquitos. Lymphatic filariasis usually occurs from many infected bites over a prolonged period.

Mosquito avoidance measures are important in reducing the risk of exposure.

The primary goal is to eliminate microfilaria from the blood of infected individuals so that transmission to another individual may be prevented. It has been shown that a single treatment with 2 drugs (albendazole with DEC or Ivermectin) is 99% effective in removing microfilaria from the blood for a full year after treatment. It is this strategy which offers hope to eliminate lymphatic filariasis from infected communities. 

Long term residents in areas of risk are strongly advised to participate in community implemented mass drug programs. At least 80% population need to be covered for the program to be successful.