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Onchocerciasis : (On- kough -sir- KY-A -sis) “ River blindness”

Onchocerciasis : (On- kough -sir- KY-A -sis) “ River blindness”. Key Learning Goals. Onchocerciasis will be defined. You will be able to identify the mode of transmission and host of the disease

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Onchocerciasis : (On- kough -sir- KY-A -sis) “ River blindness”

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  1. Onchocerciasis: (On-kough-sir-KY-A-sis)“River blindness”

  2. Key Learning Goals • Onchocerciasis will be defined. • You will be able to identify the mode of transmission and host of the disease • The burden of the disease will be defined showing the incidence and prevalence rates • Control measures through prevention and treatment will be characterized

  3. Onchocerciasis • World's second leading infectious cause of blindness • About 18 million people are currently infected with this parasite • Approximately 300,000 have been permanently blinded

  4. Onchocerciasis • Blackflies that transmit the disease abound in riverside areas, where they breed in fast-flowing water. • Onchocerciasis causes intense itching, disfiguring dermatitis, and eye lesions that can result in blindness. • Without able workers, production is greatly diminished, increasing poverty and famine.

  5. The Life Cycle http://timpanogos.files.wordpress.com/2007/09/river_blindness_cycle-carter-center-alberto-cuadra.jpg

  6. The Blackfly • 4 stages of development: egg, larva, pupa, and adult. The eggs, larvae, and pupae are confined to rivers and streams. • Eggs hatch, larvae drift and attach themselves to rocks and vegetation in flowing water. • Larvae feed by filtering nutrients from the water and grow to about 6-10 mm. They pupate within two or three weeks. • After a few days in the pupal stage the adults escape from the pupa and float to the surface in an air bubble. • Both adult male and female black flies feed on nectar and plant juices to meet their energy requirements. • Mating occurs soon after emergence. • Females of biting species then seek blood, which they require to produce eggs.

  7. Mode of Transmission • Parasites are transmitted from the bite of black flies • Simulium species • Worms spread throughout the body • Strong immune system response that can destroy nearby tissue, such as the eye.

  8. Worldwide Distribution >99% in Africa Yemen S. America Mexico Guatemala

  9. Onchocerciasis affects the body • In the human body, the larvae form nodules in the subcutaneous tissue, where they mature to adult worms. • After mating, the female adult worm can release up to 1000 microfilariae a day. • These move through the body, and when they die they cause a variety of conditions, including blindness, skin rashes, lesions, intense itching and skin depigmentation.

  10. Causes of morbidity • Microfilariae elicit the onchocerciasis syndrome that includes blindness, lymphadenitis, and dermatitis. • O volvulus infection reduces immunity and resistance to other diseases, resulting in a reduction of the life expectancy of infected individuals by approximately 13 years.

  11. The Good News…Prevention andControl Measures • Spraying of blackfly breeding sites with insecticide • Mectizan • Surgical removal of worms

  12. More Good News http://www.mectizan.org/treatment.asp

  13. Thank you

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