Onchocerciasis

Biological Impact

Onchocerciasis is caused when the body reacts to the presence of microscopic forms of O. volvulus. These worms can live under the skin and in other tissues for up to 14 years. As the worms grow, they mate and reproduce, spreading millions of new microfiliariae to other parts of the body. Itching, rashes, as well as skin depigmentation and nodules can develop as microfiliariae find loci in which to settle and grow. The most destructive consequence, however, is blindness, which is caused by long-term growth of O. volvulus in parts of the eye.

Social Impact

As a chronic infection, onchocerciasis inflicts severe social problems upon its victims.

People with the disease often suffer severe disability, especially blindness, and frequently are unable to work. Fearful of this most extreme manifestation, communities have often abandoned highly fertile areas of soil based near rivers. This trend has impeded social and economic development in badly hit rural areas of Africa.

Prevention, Treatment, and Control

Prevention and control measures against onchocerciasis include insecticide spraying to control blackflies. For instance, in West Africa, a World Health Organization-sponsored control program was able to widely reduce onchocerciasis by applying insecticides via aerial spraying over breeding sites of Simulium blackflies near fast-flowing rivers. However, given the long life cycle of the O. volvulus worms, these control efforts have failed at eradicating the disease in other parts of Africa. Thus, in 1995, the World Health Organization launched an Africa program to eliminate onchocerciasis by creating sustainable distribution systems, within communities, that would deliver ivermectin, a highly effective treatment, to at-risk and infected individuals. These efforts will eventually cover 59 million people throughout Africa. The goals of this campaign are to eliminate onchocerciasis as a serious public health problem and alleviate the social and economic hardships in individuals suffering from onchocerciasis-induced disability.