Key facts

• Lymphatic filariasis – also known as elephantiasis, is a parasitic disease transmitted by mosquitoes in tropical and subtropical regions.
• Many infected people show no symptoms but may carry the parasite in their blood.
• The painful and disfiguring symptoms of the disease can lead to stigma and prevent people from working
• Global control efforts focus on mass drug administration to interrupt transmission.

Overview

Lymphatic filariasis, often referred to as elephantiasis, is a neglected tropical disease that affects millions of people worldwide, particularly in Asia, Africa, the Pacific, and parts of the Americas. It is caused by infection with three types of parasites of the family Filariodidea.

The parasites are spread by mosquitoes and nest in the human lymphatic system, leading to abnormal swelling of limbs and other body parts. The condition is one of the leading causes of permanent disability in the world.

Signs and symptoms

The majority of people show no symptoms but spread the disease if they are bitten by a mosquito which then transmits the parasite to another person.

Typical signs and symptoms include:

• Swelling of the legs, arms, breasts, or genitals.
• Thickening and hardening of the skin, especially in swollen areas.
• Hydrocele (swelling of the scrotum in men).
• Persistent cough or wheeze
• Bacterial infections of the skin

Dangers and complications

The most significant dangers of lymphatic filariasis are long-term disability and disfigurement. The chronic swelling and thickening of tissue can lead to extreme physical and social hardship.

Recurrent infections of the skin and lymphatic tissue are common, which worsen swelling and further damage the lymphatic system. People affected by elephantiasis often experience poor mental health and social exclusion due to stigma.

In men, hydrocele may cause pain, discomfort, and difficulties with work and daily activities. Without proper management, these complications can become lifelong.

Transmission

Lymphatic filariasis is spread through the bites of infected mosquitoes. Different species of mosquitoes carry the disease in different parts of the world. The parasite can live in the body for many years and later attack the immune and lymph systems.

Lymphatic filariasis rarely occurs in casual travellers. Unlike malaria, it takes repeated bites from infectious mosquitoes for people to become infected.

Treatment

A drug called diethylcarbamazine (DEC) can treat the initial infection but it cannot treat chronic symptoms relating to damage to the lymphatic system – for example elephantiasis. Here, treatment focuses on management of swelling, skin care to prevent bacterial infections, and, where necessary, surgery to correct scrotal swelling.

Prevention

The disease has been successfully controlled since 2000 thanks to mass administration of preventive drugs to populations most at risk of the disease – a combination of albendazole, DEC or ivermectin. Populations are given the drugs once a year for at least six years until the transmission of the disease has been interrupted. Table salt fortified with DEC has also been used to prevent the spread of the disease.

Other strategies involve control of the mosquito through bed nets, insecticide spraying and controlling breeding grounds.

History

Lymphatic filariasis is an ancient disease with depictions of elephantiasis and scrotal swelling dating back hundreds of years. In 2000 the World Health Organization launched a global programme to eliminate the disease and since then 21 countries have been certified as clear. The number of infections fell by 74 per cent between 2000 and 2018.

Useful links

who.int/health-topics/lymphatic-filariasis

cdc.gov/about/lymphatic-filariasis

unitingtocombatntds.org/elephantiasis-lymphatic-filariasis

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