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About Lymphatic Filariasis

Lymphatic filariasis (LF), commonly known as elephantiasis, is caused by parasitic thread-like worms. It is thought to have been a scourge of civilisation for thousands of years, being first depicted on the ancient murals of Egypt and in the ancient medical text of China, India, Japan and Persia. Elephantiasis and hydrocoele were first associated with parasitic filarial worms and their mosquito vectors in the late 19th century by French, English and Australian physicians working with patients from Cuba, Brazil, China and India.

The transmission cycle
Lymphatic filariasis is transmitted by mosquitoes which carry infective larvae of the filarial parasites Wuchereria bancrofti or Brugia malayi from one person to the next.
The mosquitoes bite infected humans and pick up the microfilariae from the blood. The microfilariae then develop inside the mosquito into the infective larval stage in a process that usually takes seven to 21 days. The larvae then migrate to the mosquitoes’ mouth, ready to enter the bloodstream of the next unsuspecting individual the mosquito bites. The larvae migrate from the site of the bite to the lymphatic system, thus completing the life cycle.  

Symptoms
While not life threatening, LF can permanently damage the lymphatic (a network of vessels that regulate the body’s fluid and is part of the immune system) and renal systems, and thus create a lifetime of disability. The adult worms cause fluid to collect which leads to swelling in the arms, legs, breasts and genitals. This is called lymphoedema.

Acute episodes of local inflammation involving skin, lymph nodes and the lymphatic vessels often precede or accompany lymphoedema. Some of these are caused by the body’s immune response to the parasite, but most are the result of bacterial infection of the skin when normal defences have been partially lost due to the underlying lymphatic damage. Such infections cause a grotesque hardening and thickening of the skin, known as elephantiasis.

The LF parasites have a particular tendency to attack the male urogenital system. Up to 50 per cent of infected males may ultimately develop serious symptoms, such as swelling of the scrotum which, in time, may develop into massive elephantiasis of the scrotum, known as hydrocoele. The urogenital damage can lead to lifelong social and sexual disabilities and, although skin hygiene of the genital area can be helpful, the main treatment for hydrocoele is surgical repair.

Although the swelling of legs and genitals prevent patient from leading a normal life, it is the acute feverish attacks that cause them most discomfort. Most LF patients, suffers these attacks regularly - once or even twice a month - with each attack lasting anything up to seven days making them feel very poorly and make any work difficult.

Social impact
LF exerts a heavy social burden, particularly since the chronic complications are considered shameful and are often hidden. For men, the genital damage is a severe handicap leading to physical limitations, poor self-image and social stigmatisation. Persons affected by lymphoedema are sometimes considered undesirable, and are severely stigmatised. Marriage, usually an essential source of security, is often impossible for men and women with chronic implications.

Economic impact
LF further exacerbates poverty by physically incapacitating people during what should be the most productive years of their lives. Lost productivity caused by the disease costs billions of dollars across the world each year. LF also puts a tremendous strain on healthcare systems and the healthcare costs faced by patients can be prohibitive. In addition to its economic impact, LF inflicts heavy psycho-social consequences on affected individuals.

Countries with Lymphatic filariasis
Map showing Lymphatic filariasis endemic countries and of those countries, those that are using albendazole. View larger version.

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