Filariasis epidemiology and demographics

Lymphatic filariasis is widely distributed all over the world and affects as many as 120 million individuals worldwide. It is also responsible for disability in about 40 million patients. It affects children and the probability of infection increases with age. The causative worms are found predominantly in tropical areas.

• Lymphatic filariasis affects over 120 million people and it has been the leading cause of disability among filariasis patients.^[1]
• It has been reported that 1 billion people are at risk of being infected with the disease.^[2]

• Filariasis causes disability in 40% of the patients affected.^[3]

• Filariasis commonly affects children.
• It affects children before age of 5 but they remain asymptomatic and the symptoms appear after the puberty.^[2]

• Men and women are affected equally by filariasis.

• There is no racial predilection for filariasis.

• Distribution of the different nematodes causing lymphatic filariasis as the following:
  • Wuchereria bancrofti is encountered in tropical areas worldwide.
  • Brugia malayi is limited to Asia.
  • Brugia timori is restricted to some islands of Indonesia.
  • Onchocerca volvulus, which causes river blindness, occurs mainly in Africa with additional foci in Latin America and the Middle East.
  • Loa loa and Mansonella streptocerca are found in Africa.
  • Mansonella perstans occurs in both Africa and South America.
  • Mansonella ozzardi occurs only in the Americas, from Mexico south to South America and in the Caribbean.
• In endemic areas of the world (e.g., Malaipea in Indonesia), up to 54% of the population may have microfilariae in their blood.^[4] In the Americas, only four countries are currently known to be endemic: Haiti, the Dominican Republic, Guyana and Brazil.

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