Filariasis (Elephantiasis)

Filariasis is an infection transmitted by mosquitoes and caused by 3 different species of worms: Wuchereria bancrofti, Brugia malayi, and Brugia timori.

After the bite from an infected mosquito, the larvae preferentially reside in the lymphatic system.

Symptoms of acute infection are fever, swollen lymph glands, testicles etc. Long term infection results in the classic gigantic swelling of lower limbs (elephantiasis), testicles and breasts.

Where does it occur?

Wuchereria Bancrofti is seen in the tropical parts of Asia, Latin America, Africa and the Pacific Islands.

Brugia malayi is seen in southwestern India, Southeast Asia, central and northern parts of China and Koreas.

Brugia timori is seen in Timor, the islands of Flores, Alores and Roti in southeastern India.

How is it transmitted?

It is transmitted through the bite of mosquitoes that harbors the infectious larvae. The larvae migrate through the blood stream into the lymphatic system and lymph nodes where they mature over months to years. The mature worms release offspring called microfilariae into the blood stream; usually at night.

Is it contagious from person to person?

It is not contagious from person to person.

What is the risk for travelers?

A large number of repeated mosquito bites over a prolonged period of time are needed to start an infection.Therefore the risk is low for short term travelers who are in these regions for less than 3 months.

Risk is highest for long term travelers like missionaries, peace corps volunteers etc.

How soon after exposure will I develop symptoms?

Symptoms are usually seen anywhere from 6 months (acute symptoms of fever, swollen glands etc) to 2-6 years (chronic symptoms of swollen extremities, testicles etc.) after exposure.

What are the signs and symptoms?

Acute symptoms are of fever, headache, swollen lymph nodes, streaky red painful lymphatic channels on legs and arms. One can also see painful swollen testicles. The symptoms last for a few days to weeks and resolve but can recur periodically.

The microfilariae are usually released from the lymphatic system at night, they can migrate to the lungs and cause shortness of breath, wheezing, fever and an elevated eosinophil count in the blood; a syndrome called tropical pulmonary eosinophilic syndrome.

With chronic infection over years, one can develop obstruction of the lymph glands, resulting in huge swollen limbs (elephantitis), scrotum, breast, etc.

Are there any lab tests to diagnose the illness?

Thick and thin smears of blood can demonstrate the larvae. Blood antibody tests by ELISA and PCR tests are also available.

Is there any treatment?

Medications like ivermectin, diethylcarbazine citrate and albendazole are used to treat the infection; usually in combinations. Antibiotics are not usually curative. Swollen limbs, testicles and breasts may require surgical treatment.

What preventive measures can be taken?

Long term residents should take insect safety measures.

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