Onchocerciasis is one of several neglected tropical diseases and is the result of infection with the parasitic worm Onchocerca volvulus. It transmits to humans through multiple bites of the Simulium genus blackfly. The species of Simulium which serve as vectors will vary in geographic regions of the world where the disease takes place.
Populations at Risk
The blackfly resides and breeds near fast-flowing streams or rivers, and since humans who acquire the infection may become blind, another name for the medical condition is River Blindness. Approximately 99 percent of people with the disease reside in Africa; the major disease burden is in sub-Saharan Africa (Centers for Disease Control, 2010).
It also infects people in Yemen, the Arabian Peninsula, and the Americas. Specifically, it occurs in Colombia, Ecuador, Mexico, Brazil, Guatemala, and Venezuela. But onchocerciasis is mostly present in West and Central Africa. Worldwide, this disease is the second leading infectious cause of blindness. The World Health Organization estimates that there are 37 million people on the globe with this medical condition.
Since agricultural villages which are proximal to fast-flowing rivers and streams are at risk for human acquisition of onchocerciasis, many people have left those communities and moved to large cities in Africa. This migration has led to poverty, unemployment, sanitation problems, and malnutrition. In other words, the economic loss and social burden from the disease are quite serious.
International travelers may acquire the disease too if they remain in an area where the disease occurs commonly. And travelers who stay there for at least three months are more likely to get it than casual or short-term visitors. This means that missionaries, Peace Corps workers, adventure travelers, and field researchers are at risk for onchocerciasis in these regions.
Nevertheless, long-term travelers may not acquire the infection when they travel to regions where the transmission rates are low such as the Americas.
Mortality Rate Zero
Onchocerciasis does not cause immediate death of the patient; in fact, the mortality rate from it is zero. However, it may shorten the patient’s lifespan by several years especially if he or she does not obtain medical treatment.
Sources
- Centers for Disease Control. (2010). Parasites—Onchocerciasis (also known as River Blindness). Retrieved January 11, 2012.
- World Health Organization. (2012). Onchocerciasis. Retrieved January 11, 2012.
Disclaimer: The information contained in this article is for educational purposes only and should not be used for diagnosis or to guide treatment without the opinion of a health professional. Any reader who is concerned about his or her health should contact their physician for advice.
Michael Koger - Dr. Koger obtained his medical education at Meharry Medical College and specialized in Internal Medicine.
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