The species of mosquitoes that transmit malaria and yellow fever, diseases caused by protozoa and viruses also transmit filariasis, caused by a parasitic worm- a nematode or round worm. Filariasis affects 300 million people living in tropical and sub tropical areas of the world. The worm invades the subcutaneous tissues and lymph system of the human body, blocking the flow of lymph and producing symptoms of inflammation, edema, and abscesses and in one form of the disease, blindness. Filariasis is not unknown to Americans; some 15,000 soldiers contracted the disease during World War II fighting in the Pacific Theatre, and cases have been reported along the Carolina coast area. But most of the victims of filariasis live in a region extending from Africa through Asia to the islands of New Guinea and Borneo. Its symptoms can develop insidiously during an incubation period that may last from three months to a year after infection. There can be brief attacks of a low grade fever, with chills and sweating, headache, nausea and muscle pain. The patient may also feel sensitive to bright lights. Signs and symptoms more specifically related to filariasis are the appearance of red, swollen skin areas with tender spots that indicate the spread of threadlike worms through the lymphatic system. Most likely sites for the first signs of filariasis are the lymph vessels of the legs, with later involvement of the groin and abdomen, producing the swollen lower frontal effect known as elephantiasis.
