Precious eyesight can be saved, river blindness is one of the leading causes of preventable blindness worldwide. River Blindness is a tropical disease caused by a parasitic worm.
About 300,000 people are blind because of the parasitic worm Onchocerca volvulus and another 800,000 have visual impairment. Nearly 99% of infected persons live in Africa.
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| Man in Tanzania Africa with River blindness |
What is River Blindness?
River
Blindness is transmitted through repeated bites by black flies that bite during
the day. The disease is called River Blindness because the blackfly that
transmits the infection lives and breeds near fast-flowing streams and rivers
and the infection can result in blindness.
Humans
become infected when blackflies deposit Onchocerca infective larvae into the
skin when biting to extract blood. Once inside the human body, the larvae
mature into adults in around 3 months to 1 year. Most adult female worms live
in fibrous nodules under the skin and sometimes near muscles and joints.
Adult
male worms are usually found near the female worms. Nodules form around the
worms as part of the interaction between the parasite and its human host.
Inside the nodules the worms are relatively safe from the human immune
response.
As
adults, female worms produce thousands of new larvae daily. The larvae become
detectable in the skin 10 to 20 months after the initial infection. The adult
worms can live up to 15 years inside the human body, and their larvae have a
lifespan up to 2 years.
The
death of microfilariae is very toxic to the skin and the eye, producing
terrible itching and various eye manifestations (lesions). After repeated years
of exposure, these lesions may lead to irreversible blindness and disfigurative
skin diseases sometimes named "leopard" skin and "lizard"
skin.
How Common is River Blindness?
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| Eye exam |
Worldwide river blindness is second only to trachoma as an infectious cause of preventable blindness. In some West African communities, the disease had blinded about 50% of men over the age of 40 years. People with major river blindness infections will usually have one or more of three conditions of itchy skin rash, eye disease, and/or nodules under the skin.
The
World Health Organization estimates that at least 25 million people are
infected and 123 million people live in areas that put them at risk of
infection. About 300,000 people are blind because of the parasite and another
800,000 have visual impairment. Nearly 99% of infected persons live in Africa. River
Blindness is commonly treated with an oral medicine called ivermectin however; there
is neither a vaccine nor recommended drug available to prevent River Blindness.
Did
you know?
Trachoma
is the world's leading cause of preventable blindness and occurs where people
live in overcrowded conditions with limited access to water and health care.
