A) Onchocerciasis Life Cycle Adult worms are threadlike creatures what live encapsulated within fibrous nodules beneath the skin. The female gives birth to over 2000 snakelike larvae called microfilariae every day for 15 to 20 years. Upon birth the microfilariae disperse to the upper layers of the skin and even the eye. The biting backfly ingests the microfilariae when it bites and infected host. The parasite then goes through transformation in the gut, then the muscles of the thorax before it goes into its final metmorphasis into the filariform larva (infectious now). Cycle takes about two weeks and the larva escapes into humans when the blackfly bites a human. In the skin they grow to adulthood and mate where the female produces more microfilariae. Key reservoirs are infected humans where adult filariae live anywhere from 15-20 years Vector = blackfly ( S. damnosum ) which is found near highly fertile rivers. The female blackfly deposits eggs in fast-flowing well-oxygenated water. The larvae absorb nutrients like filter
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