What is filariasis?
Filariasis is an infection caused by a parasitic worm and is transmitted by insect-bites. It is more prevalent in the tropical areas of Africa, Asia, Central and South America. In India, it is common in eastern Uttar Pradesh and Bihar.
This disease spreads from person to person by mosquito bites. When a mosquito bites an infected person, microscopic worms circulating in his blood enter and infect the mosquito. These worms then pass to the other person when this infected mosquito bites him. The worms transferred from the mosquito, move through the skin, and travel to lymph vessels, where they grow into adults. An adult worm lives for about seven years. The adult worms mate and release millions of microscopic worms into the blood.
There are eight different types of this worm, out of which three are responsible for causing the disease: Wucheria bancrofti and Brugia malayi cause lymphatic filariasis, and Onchocera volvulus causes onchocerciasis (river blindness).
What are the symptoms?
Adult worms live in the lymph vessels and nodes, while the younger forms are found primarily in the blood. The symptoms are seen four to twelve months after infection, and usually begin with swelling and inflammation in the genitals or extremities. Other symptoms include fever, pain and swelling of lymph glands, headache, and inflammation of the lymph drainage areas, swelling of the scrotum, skin rashes and blindness. Progression of the disease often causes enlargement of the legs resulting in a condition called elephantiasis or lymphatic filariasis. This enlargement occurs due to the presence of lymphoedema or presence of fluid in the tissue spaces that may begin to accumulate in the first 24 hours. The skin becomes thick and rough and the increase in the size and weight of the affected parts lead to disability.
How is it diagnosed?
Filariasis can be diagnosed by conducting a blood test that directly shows the presence of worms. Circulating filarial antigen is a standard test for diagnosing Wuchereria bancrofti infections.
What is the treatment?
The treatment of filariasis consists of using medicines that kill the worms combined with the treatment to relieve the symptoms. Diethylcarbamazine
are effective drugs in the treatment of most filarial infections. Other drugs include albendazole
. Antihistamines or corticosteroids
can decrease allergic reactions. In case of elephantiasis, one needs to take a yearly dose of medicine that kills the microscopic worms in the blood. This does not kill the adult worms, but it does prevent transmission of the disease to other persons. Even after the adult worms die, swelling of arms, legs, breasts, or genitals, may be present. One may keep the swelling from getting worse by:
- Carefully washing the swollen area with soap and water everyday.
- Using anti-bacterial anti-fungal creams on the wound.
- Elevate and exercise the swollen arm or leg to move the retained fluid and improve lymph flow.
- Use compression bandages to reduce accumulation of fluid in the legs.
How can it be prevented?
Prevention includes giving medicine that kills the microscopic worms, to the entire community in the areas where the infection is prevalent. Avoiding mosquito bites is another form of prevention. These mosquitoes usually bite between the hours of dusk and dawn. One can follow these steps, if living in an infected area:
- Sleep under a mosquito net.
- Use mosquito repellents on the exposed skin.
- Take a yearly dose of medicine that kills the worms in the blood.