Elephantiasis is a condition characterized by gross enlargement of an area of the body, especially the limbs. Other areas commonly affected include the external genitals. Elephantiasis is caused by obstruction of the lymphatic system, which results in the accumulation of a fluid called lymph in the affected areas.
Functioning as part of the immune system, the lymphatic system helps to protect the body against infection and disease. It consists of a network of tubular channels (lymph vessels) that drain a thin watery fluid known as lymph from different areas of the body into the bloodstream. Obstruction of these vessels results in the massive swelling and gross enlargement characteristic of elephantiasis.
In areas where filariasis is endemic, the most common cause of elephantiasis is a parasitic disease known as lymphatic filariasis and, in the medical literature, the terms lymphatic filariasis and elephantiasis may be used interchangeably. Elephantiasis due to lymphatic filariasis may also be referred to as "true" elephantiasis. In most areas, the lymphatic damage associated with elephantiasis has other causes including certain sexually transmitted diseases (e.g., lymphogranuloma venereum); tuberculosis; an infectious disease called leishmaniasis; repeated streptococcal infections; leprosy; and environmental factors such as exposure to certain minerals (e.g., silica). In some cases, no cause can be identified (idiopathic).
Recently a team of researchers funded by the National Institute of Allergy and Infectious Diseases (NIAID), one of the National Institutes of Health (NIH), has recently revealed the genetic secrets of one of these parasites. The researchers report solving the complete genome of Brugia malayi, one of the worms that causes the often debilitating disease elephantiasis.