What causes filaria?

Filariasis, commonly known as elephantiasis, is a group of diseases caused by parasitic worms that live in the lymphatic system. The three main species of filarial worms responsible for the majority of cases are Wuchereria bancrofti, Brugia malayi, and Brugia timori.

Transmission of filarial worms occurs when an infected mosquito bites a human and injects the infective larvae (microfilariae) into the skin. These larvae then migrate to the lymphatic vessels, where they develop into adult worms. Adult female worms produce large numbers of microfilariae, which circulate in the bloodstream.

The presence of filarial worms and microfilariae can cause a range of symptoms, including:

1. Lymphatic Obstruction: The adult worms can obstruct the lymphatic channels, leading to a buildup of lymphatic fluid. This can cause swelling in various parts of the body, such as the legs, arms, scrotum (in males), and breasts (in females). In advanced cases, this swelling can become severe and lead to elephantiasis.

2. Inflammatory Reactions: The body's immune response to the presence of filarial worms and microfilariae can lead to inflammation and damage to the lymphatic system. This can result in fever, chills, and pain.

3. Skin Changes: Filarial infections can also cause changes in the skin, including thickening, hardening, and discoloration.

4. Renal and Genitourinary Problems: In some cases, filariasis can affect the kidneys and urinary system, causing proteinuria (the presence of protein in the urine) and kidney damage. In males, filariasis can lead to inflammation and swelling of the testicles (orchitis) and epididymis (epididymitis).

5. Lymphatic Filariasis: Lymphatic filariasis, caused primarily by Wuchereria bancrofti and Brugia malayi, affects the lymph nodes and lymphatic vessels, leading to chronic swelling, tissue fibrosis, and skin thickening in the affected areas.

It's important to note that filariasis is a preventable and treatable disease. Mass drug administration (MDA) campaigns, which involve distributing anti-filarial medications to entire populations in affected regions, have been successful in reducing the transmission of filarial worms and improving the health outcomes of individuals living in endemic areas.