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Onchocerciasis is the world’s second
leading infectious cause of blindness. The
disease spreads from person to person by
the bite of a blackfly. When a blackfly bites
a person who has onchocerciasis,
microscopic worm larvae (called
microfilariae) in the infected person's skin
enter and infect the blackfly. The larvae
develop over 2 weeks in the fly to a stage
that is infectious to humans. An infectious
blackfly will typically drop larvae when
biting a person. The larvae then penetrate
the skin to infect the person. Because the
worms reproduce only in humans but need
to complete some of their development
inside the blackfly, the intensity of human
infection (number of worms in an
individual) is related to the number of
infectious bites sustained by an individual.
Blindness is usually seen in the setting of
longstanding and intense infection.
Where:
Onchocerciasis is locally transmitted in
thirty countries of Africa, 13 focal areas
located in 6 countries (Mexico,
Guatemala, Ecuador, Colombia,
Venezuela, and Brazil) in the Americas,
and in Yemen in the Middle East.
Treatment:
Onchocerciasis is the second leading
infectious cause of blindness and can
cause debilitating and disfiguring skin
disease. There is neither a vaccine nor
recommended drug available to prevent
onchocerciasis. However, the worldwide
burden of onchocerciasis has been
considerably reduced as the result of very
successful disease control programs led by
the World Health Organization (WHO).
These programs are based on control of
the blackfly population and/or mass
administration to affected communities of
an oral drug called ivermectin
(MectizanTM), that is donated by Merck &
Co., Inc. As a result of these programs,
millions of people are at greatly reduced
risk of debilitating itching, disfigurement,
and blindness caused by onchocerciasis.
CDC
http://www.cdc.gov/parasites/onchocerci
asis/index.html
Global Network
http://globalnetwork.org/aboutntds/factsheets/onchocerciasis
Helen Keller International
http://www.hki.org/preventingblindness/onchocerciasis-control
The Carter Center
http://www.cartercenter.org/health/river_
blindness/oepa.html
TropIKA: Tropical Diseases Research
http://www.tropika.net/index.html
World Health Organization
http://www.who.int/blindness/causes/priori
ty/en/index3.html