Onchocerciasis: (On-kough-sir-KY-A-sis) “River blindness” Goodmoring everyone. Today we will talk about Onchocerciasis which is also known as river blindness. I found this picture on the wordpress website and thought it was a good picture to give you some idea of the burden of this disease. This river blindness statue is located on the Carter Center grounds depicts a child leading a man with a stick. It is common for children to lead blind adults around their communities.

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

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 River blindness is a parasitic infection that affects 18 million people, threatens the vision of about one million, and leaves a third of those irreversibly blind.

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. Onchocerciasis is present in 36 countries of Africa, the Arabian peninsula and the Americans. The prevalence of blindness is high, young, able-bodied people who fearful of contracting onchocerciasis leave their villages, often abandoning rich farmland.  As a public health problem the disease is most closely associated with Africa, where it constitutes a serious obstacle to socio-economic development. The disease causes chronic suffering and severe disability

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

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 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. microscopic parasites are transmitted into the human body through the bite of black flies, which breed along swiftly flowing rivers in endemic areas, primarily in Africa. The unsuspecting victims are infected while undertaking daily tasks, such as farming and fishing.

Worldwide Distribution >99% in Africa Yemen S. America Mexico Guatemala This slide the worldwide distribution of Onchocerciasis.

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 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 microfilariae can also cause inflammation of regional lymph glands which remove foreign material from the distal skin. This inflammation along with the loss of tissue elasticity can lead to protruding lymph glands enfolded in pockets of skin. This condition is especially prominent in the areas around the scrotum (often called the 'hanging groin' effect) and in severe cases is classified as minor elephantiasis.

The Good News… Prevention and Control Measures Spraying of blackfly breeding sites with insecticide Mectizan Surgical removal of worms

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

Thank you Thank you for your attention. Are there any questions?