Posted by: keherenf | October 11, 2007

Onchocerciasis (River Blindness)


Imagine having the skin on your face infested with tiny parasitic worms that you cannot get rid of. Sound straight out of a horror movie? Well, for those with river blindness, this is a hellish reality.

Pathology: Onchocerciasis (River Blindness) is caused by a filaria worm. This worm gets into the human through the bite of a blackfly. Most blackflies live by fast-flowing streams and rivers,  thus those who are infected usually live close to such bodies of water, giving it the nickname “river blindness”. Once the worm is in the skin, it births thousands of baby worms (microfilariae) which move to the eyes and the skin. When the microfilariae die, their decomposing bodies produce toxins that cause extreme itchiness and lesions. After enough time, this toxicity causes blindness and extreme skin disfiguration.


Symptoms: Some may not show any symptoms at all, while others will display the following most common symptoms: dermatitis (itchy skin), eye lesions, subcutaneous nodules (resembles acne or a skin rash)

Treatment: The oral medication Ivermectin can be given every 6-12 months. It does not kill the adult parasites, but reduces the microfilariae so the disease cannot progress.

Epidemiology: Occurs mainly in Central and West Africa, 6 countries in Latin America, Yemen, and the Arabian Peninsula


Morbidity (# of people affected): 17.7 million are infected with the parasite. Of these, it is currently estimated that about 500,000 are blind due to this disease. In some parts of Africa, over 50% of males over 40 are afflicted. 99% of all of the river blindness cases occurs in Africa.

Mortality (# deaths): This disease does not lead to death

Prevention: Although there is no vaccination or prophylaxis, if you are in an area prone to black river disease, make sure to use bug repellent with DEET and wear clothes that fully cover the body.


Interesting facts:

  • Unlike malaria, to be infected with this disease requires more than one bite from an infected fly.
  • The incubation period for the worms in the body is 9-24 months
  • A female worm can live between 10-15 years and reproduce millions of microfilariae

Eradicating River Blindness: Drug company Merck has pledged to donate the drug Mectizan, an effective medication for river blindness, as long as people need it. This has drastically reduced the number of those suffering from this condition, but has also posed a public health issue as to how to effectively distribute the medication. The Carter Center also has a program to try and eradicate this problem.
For more information:

WHO (World Health Organization)

CDC (Center for Disease Control) 

The Carter Center 



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