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Filarial diseases


Global View

What are the filarial diseases?

Lymphatic filariasis (Elephantiasis)
120 million infected
40 million symptomatic
DALYs estimated at 6 million world-wide *
More than 1.3 billion people at risk
More than 25 million men with genital disease and
15 million people with lymphoedema.
Onchocerciasis (River Blindness)
25.7 million infected
746,000 visually impaired

265,000 blinded
DALYs estimated at 389,000 worldwide *
Loiasis (Loa loa) (African eye worm)
14.4 million infected
Often asymptomatic
Can cause itchy swellings (Calabar swellings)
* The Global Burden of Disease Report, WHO, 2004.
 
Geography
Lymphatic filariasis affects an estimated 120 million people living in tropical areas of the world. Approximately two thirds live in South-East Asia, almost one third live in sub-Saharan Africa and Egypt, and the remainder in the western Pacific islands, Brazil, Guyana, Haiti and the Dominican Republic.
Onchocerciasis is almost exclusively confined to West and Central Africa, although there are localized infections in Yemen and some South American countries.
Loiasis occurs in the rain forest and swamp areas of West Africa and in Central Africa on the Democratic Republic of Congo/South Sudan border. 
Transmission
Onchocerciasis (River blindness), Lymphatic filariasis (Elephantiasis) and Loiasis (Loa loa infection) are all caused by parasitic filarial nematode worms that are transmitted between humans by blood-sucking insects.

Onchocerciasis is caused by Onchocerca volvulus, transmitted by the bite of an infected female blackfly; lymphatic filariasis is caused by Wuchereria bancrofti (90% of cases), Brugia malayi (most of the remainder) and Brugia timori, and is transmitted by various mosquito species;  Loa loa worms are transmitted by the bites of Mango flies or by Deer flies.
 
Impact
Filarial diseases are the most devastating of the neglected tropical diseases in terms of social and economic impact.  Families and communities have to bear the brunt of long-term healthcare, coupled with loss of productivity and earnings due to the incapacity to work.  The disabling and disfiguring effects on the individual lead to social stigmatization and isolation.
Symptoms
Filarial disease is not particularly life-threatening, but Onchocerchiasis and Lymphatic filariasis cause long-term suffering and chronic disease with life-long disabilities in millions of people worldwide, such as blindness (onchocerciasis) and swollen limbs and genitals (lymphatic filariasis). Loiasis is usually considered asymptomatic but can cause localized swellings associated with localized and generalized itching.
 
Patient Treatments Needs
Current treatments for onchocerciasis and lymphatic filariasis target the juvenile microfilariae. These drugs can also kill the microfilariae produced by Loa loa. Because of the high load of these microfilariae in many patients, their rapid death can cause severe side effects resulting from the large amount of debris in capillaries. These side effects include encephalopathy and kidney damage. A new treatment for onchocerciasis and lymphatic filariasis in areas where Loa loa is endemic which is effective exclusively against the adult stage parasites will avoid the severe adverse reactions associated with death of the juvenile stage Loa loa parasites and will lead to fewer cycles of treatment in prevention and control programmes.
Tags: Filarial diseases

Filarial Diseases

168 million infected by the 3 diseases

More than 1 billion people at risk

In 81 countries



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