Introduction

Onchocerciasis, or river blindness, has historically been one of the most important causes of infectious blindness. It is endemic to sub-Saharan Africa and six countries of Central and South America. The disease, although not fatal, results in severe socioeconomic disruption of affected communities. Onchocerciasis is caused by infection with the nematode Onchocerca volvulus. O. volvulus is an obligate parasite of humans, which is notable because most Onchocerca are parasites of ungulates. The sexual stages of the parasite exist in the human host. The adult females produce large numbers of larvae (known as microfilaria), which distribute themselves throughout the dermis of an infected individual, although they are also capable of invading other organs, such as the eye. The parasite is transmitted between infected humans by vector black flies of the genus Simulium. When a black fly takes a blood meal from an infected individual, microfilaria are ingested along with the blood. The microfilaria undergo two molts to form infective larvae, or L3, which migrate to the head capsule of the fly. When an L3-infected fly feeds, the L3 are introduced. The L3 then undergo two more molts to produce adult parasites, completing the life cycle. The prepatent period, or the time between the introduction of the L3 into a human host and the final development of a fertile female, is 18-24 months.

Three internationally supported programs to eliminate onchocerciasis as a public health problem have been initiated in the past 30 years. These included the Onchocerciasis Control Programme in West Africa (OCP), which was instrumental in eliminating blinding onchocerciasis as a public health problem in 11 countries of West Africa. The OCP conducted active operations in the period of 1975-2002. The OCP primarily relied on a strategy of vector control supplemented in later years by ivermectin distribution, the single drug known to be safe and effective for the treatment of onchocerciasis. Two programs, the African Program for Onchocerciasis Control (APOC) and the Onchocerciasis Elimination Program in the Americas (OEPA), are currently active. Both solely rely on ivermectin distribution. The goal of this article is to review the development of DNA-based diagnostics for

O. volvulus and their application both to onchocerciasis control and to biogeographical studies.

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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