Symptoms, transmission, and current treatments for lymphatic filariasis

Lymphatic filariasis

Symptoms, transmission, and current treatments for lymphatic filariasis

What is lymphatic filariasis?

Lymphatic filariasis (LF) – also called elephantiasis – is caused by parasitic worms spread by the bites of infected mosquitoes. The larvae migrate to the lymphatic vessels, where they mature and reproduce. Over time, adult filarial worms trigger inflammation in the lymphatic system, causing damage to lymphatic vessels, even in individuals who show no symptoms. This damage leads to impaired lymphatic function, particularly in the lower limbs, making people living with LF more vulnerable to repeated bacterial infections. These secondary infections often result in ‘acute attacks,’ the most common clinical manifestation of LF, and significantly contribute to worsening lymphoedema (swelling of the legs and feet). Acute attacks typically involve localized pain and swelling, along with fever and chills.

What is the impact of lymphatic filariasis?

657 million people are at risk of lymphatic filariasis
57 million people living with lymphatic filariasis
Endemic in 39 countries
15 million people living with lymphoedema (swelling of the legs and feet)
25 million men living with hydrocele (swelling of the scrotum)

What are the current treatments for lymphatic filariasis?

Albendazole, ivermectin, and diethylcarbamazine citrate (DEC) are currently used in mass drug administration programmes to reduce transmission, but they kill only juvenile worms and have limited effect on adult parasites. Without a drug that kills both juvenile and adult worms, regional and global goals to eliminate the disease may be out of reach.

What new treatments for lymphatic filariasis are needed?

New treatments that can kill both adult and juvenile worms are needed – and these need to be suitable for all people who need them, including pregnant women, children, and people with co-morbidities.

What lymphatic filariasis treatments are we working on?

We are working with the Indian Council of Medical Research to test oxfendazole as a treatment for lymphatic filariasis. If proven effective, the drug may bring a powerful new tool in efforts to eliminate the disease. We are also working with partners across Europe and sub-Saharan Africa to develop and test a safe, child-friendly, field-adapted formulation of the existing drug ivermectin.

How do you get lymphatic filariasis?

Lymphatic filariasis is spread by the bites of infected mosquitoes. The larvae from the mosquito burrow into the skin and migrate to the lymphatic vessels, where they mature and reproduce. The adult worms then provoke chronic inflammation, which can ultimately impair lymphatic function and lead to painful swelling and thickened skin.

What are the symptoms of lymphatic filariasis?

Most people living with lymphatic filariasis are infected when they are children, but the disease is most devastating years later when damage to the lymphatic system can result in abnormal enlargement of body parts, pain, severe disability, and social stigma.

How is lymphatic filariasis diagnosed?

Lymphatic filariasis is diagnosed by detecting the microscopic parasite larvae in the blood or by identifying specific parasite antigens and antibodies through specialized tests.

More information

WHO factsheet

Last updated: October 2026

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