onchocerciasis on kough sir ky a sis river blindness n.
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Onchocerciasis : (On- kough -sir- KY-A -sis) “ River blindness”

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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

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

key learning goals
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
  • 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
  • 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.
the life cycle
The Life Cycle


the blackfly
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.
mode of transmission
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.

Worldwide Distribution

>99% in Africa


S. America



onchocerciasis affects the body
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.
causes of morbidity
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.
the good news prevention and control measures
The Good News…Prevention andControl Measures
  • Spraying of blackfly breeding sites with insecticide
  • Mectizan
  • Surgical removal of worms

More Good News