USAID's NTD Program

Lymphatic Filariasis

Life Cycle

Step 1: An infected mosquito deposits microscopic larvae while biting a person.

Step 2: The larvae migrate to the human lymphatic system.

Step 3: In the lymphatic system, the larvae mature into adult worms, where they mate and form nests. These nests cause blockages, resulting in fluid collection, swelling, and fever. Adult worms live for about five to seven years.

Step 4: Female worms produce millions of microfilariae that swarm in the blood at night when mosquitoes bite, continuing the cycle.

Step 5: When a mosquito bites a person who has lymphatic filariasis, it ingests the microfilariae and becomes infected.

Step 6 and Step 7: While inside the mosquito, the microfilariae develop over a period of a week into infectious larvae, and the cycle continues.

While infections are contracted throughout life, most individuals can remain asymptomatic for years, with symptoms emerging during adolescence and adulthood.

Learn more about lymphatic filariasis:

• Epidemiology
• Symptoms
• Diagnosis
• Treatment
• Prevention, Control, and Elimination
• Back to Lymphatic Filariasis Overview