Filariasis is a disease caused by parasitic roundworms of the Filarioidea type, which are transmitted to humans as larvae by certain mosquitoes and flies. They then grow into adults inside the human body. Different species of worm prefer to live in different parts of the body. The worm pictured, Wuchereria bancrofti, lives in the lymph system and can cause a drastic swelling of tissues known as elephantiasis.
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