Main facts filariasis
Lymphatic filariasis affects the lymphatic system and can lead to an abnormal increase in the volume of certain parts of the body, leading to pain, severe disability and social stigma.
In 54 countries around the world, 947 million people are at risk of lymphatic filariasis and need preventive chemotherapy to stop the spread of the disease.
In 2000, more than 120 million people were infected, and about 40 million people were deformed and disabled by the disease.
Lymphatic filariasis can be eliminated by stopping the spread of infection by chemoprevention involving 2 safe drugs, repeated every year for at least 5 years. Since 2000, 6.2 billion treatments have been distributed to stop the spread of infection.
351 million people no longer need preventive chemotherapy because of the successful implementation of WHO’s strategies.
A set of recommended basic care helps alleviate suffering and prevent disability that can occur in people with lymphatic filariasis.
Lymphatic filariasis, commonly known as elephantiasis, is one of the neglected tropical diseases. The infection occurs when the worm parasites responsible for the disease are transmitted to humans by mosquitoes. Usually contracted in childhood, this infection causes hidden damage in the lymphatic system.
The visible, painful and severely disfiguring manifestations of the disease, namely lymphoedema, elephantiasis and swelling of the scrotum, only appear later in life and may result in permanent disability. Affected subjects do not only suffer from physical disabilities; they are also affected by mental disorders and social and financial problems, which are all agents of stigmatization and poverty.
Currently, 856 million people in 52 countries live in areas requiring preventive chemotherapy to prevent the spread of infection. It is estimated that 25 million men worldwide have a hydrocele and more than 15 million people suffer from lymphoedema. At least 36 million people remain with these chronic manifestations of the disease.
The elimination of lymphatic filariasis can prevent unnecessary suffering and contribute to the reduction of poverty.
Cause and transmission of filariasis
Lymphatic filariasis is caused by infection with nematodes (roundworms) of the family Filaridae. These wire worms, which look like wires, are of 3 types:
Wuchereria bancrofti is responsible for more than 90% of cases;
Brugia malayi, which is responsible for most of the remaining cases;
Brugia timori, which also causes the disease in some cases.
Adult filariae lodge in the lymphatic vessels and disrupt the normal functions of the lymphatic system. They have a longevity of 6 to 8 years and, during their lifetime, produce millions of microfilariae (small larvae) that circulate in the blood.
Infection of a mosquito by microfilariae occurs when the mosquito bites an infected host and ingests its blood. The microfilariae reach the infective stage inside the mosquito, then, when it infects someone else, they are released at the level of the skin, which becomes their point of entry into the body of the subject. The larvae then migrate to the lymphatic vessels where they mature, thus perpetuating the cycle of transmission.
Lymphatic filariasis is transmitted by different types of mosquitoes, including those of the Culex genera, widely distributed in urban and semi-urban areas; Anopheles, mostly present in rural areas, and Aedes that are mainly treated in Pacific endemic islands.
Lymphatic filariasis can take on asymptomatic, acute or chronic forms. The majority of infections are asymptomatic, with no outward signs of infection. However, these asymptomatic infections cause damage to the lymphatic system and kidney damage, and alter the body’s immune system.
When lymphatic filariasis becomes chronic, it leads to lymphoedema (swelling of the tissues) or elephantiasis (thickening of the skin / tissues) of the limbs and hydrocele (accumulation of fluid). Breasts and genitals are frequently affected.
These physical deformities often lead to social stigma, mental health problems, loss of income, and increased medical expenses for patients and their caregivers. The socio-economic burden of isolation and poverty is enormous.
Chronic lymphedema or elephantiasis is often accompanied by acute localized inflammations