Hygiene
Lymphatic filariasis
Lymphatic Filariasis Burkina Faso . Photo Marcus Perkins Fir GSK
Fact sheet Updated March 2017
Key facts
• Lymphatic filariasis impairs the lymphatic system and can lead to the abnormal enlargement of body parts , causing pain , severe disability and social stigma .
• 947 million people in 54 countries worldwide remain threatened by lymphatic filariasis and require preventive chemotherapy to stop the spread of this parasitic infection .
• In 2000 over 120 million people were infected , with about 40 million disfigured and incapacitated by the disease .
• Lymphatic filariasis can be eliminated by stopping the spread of infection through preventive chemotherapy with safe medicine combinations repeated annually for at least 5 years . 6.2 billion treatments have been delivered to stop the spread of infection since 2000 .
• 351 million people no longer require preventive chemotherapy due to successful implementation of WHO strategies .
• A basic , recommended package of care can alleviate suffering and prevent further disability among persons living with disease caused by lymphatic filariasis .
The disease
Lymphatic filariasis , commonly known as elephantiasis , is a neglected tropical disease . Infection occurs when filarial parasites are transmitted to humans through mosquitoes . Infection is usually acquired in childhood causing hidden damage to the lymphatic system .
The painful and profoundly disfiguring visible manifestations of the disease , lymphoedema , elephantiasis and scrotal swelling occur later in life and can lead to permanent disability . These patients are not only physically disabled , but suffer mental , social and financial losses contributing to stigma and poverty .
Currently , 947 million people in 54 countries are living in areas that require preventive chemotherapy to stop the spread of infection .
The global baseline estimate of persons affected by lymphatic filariasis was 25 million men with hydrocele and over 15 million people with lymphoedema . At least 36 million persons remain with these chronic disease manifestations . Eliminating lymphatic filariasis can prevent unnecessary suffering and contribute to the reduction of poverty .
Cause and transmission
Lymphatic filariasis is caused by infection with parasites classified as nematodes ( roundworms ) of the family Filariodidea . There are 3 types of these thread-like filarial worms :
• Wuchereria bancrofti , which is responsible for 90 % of the cases
• Brugia malayi , which causes most of the remainder of the cases
• Brugia timori , which also causes the disease .
Adult worms lodge in the lymphatic vessels and disrupt the normal function of the lymphatic system . . The worms can live for an average of 6 – 8 years and , during their life time , produce millions of microfilariae ( immature larvae ) that circulate in the blood .
Mosquitoes are infected with microfilariae by ingesting blood when biting an infected host . Microfilariae mature into infective larvae within the mosquito . When infected mosquitoes bite people , mature parasite larvae are deposited on the skin from where they can enter the body .
The larvae then migrate to the lymphatic vessels where they develop into adult worms , thus continuing a cycle of transmission .
Lymphatic filariasis is transmitted by different types of mosquitoes for example by the Culex mosquito , widespread across urban and semi-urban areas , Anopheles , mainly found in rural areas , and Aedes , mainly in endemic islands in the Pacific .
Symptoms
Lymphatic filariasis infection involves asymptomatic , acute , and chronic conditions . The majority of infections are asymptomatic , showing no external signs of infection . These asymptomatic infections still cause damage to the lymphatic system and the kidneys , and alter the body ’ s immune system . When lymphatic filariasis develops into chronic conditions it leads to lymphoedema ( tissue swelling ) or elephantiasis ( skin / tissue thickening ) of limbs and hydrocele ( scrotal swelling ). Involvement of breasts and genital organs is
36 Africa Water , Sanitation & Hygiene • May - June 2017