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Onchocerca v olvulus

Onchocerca v olvulus. By Patrick Foote. Is a nematode. Causes Ochocerciasis or “river blindness” Nematode does not cause blindness, but its endosymbiont Wolbacia pipientis (bacteria) Second leading cause of blindness.

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Onchocerca v olvulus

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  1. Onchocercavolvulus By Patrick Foote

  2. Is a nematode. • Causes Ochocerciasis or “river blindness” • Nematode does not cause blindness, but its endosymbiontWolbaciapipientis (bacteria) • Second leading cause of blindness. • Estimated 18 million suffer from Ochocerciasis, and 270,000 cases of blindness.

  3. Taxonomy • KingdomAnimalia • Phylum Nematode • ClassRhabditea • OrderSpiruida • SuperfamilyFilaroidea • FamilyOnchocercidae • GenusOnchocerca • Species Volvulus

  4. Hosts • Definitive: Humans (only ones) • Intermediate: Black fly (Simuliumyahense)

  5. Geographic • Central and South America. • Mainly Africa

  6. Morphology • Males are 19 to 42 cm long and 130 to 210 um wide. • Females are 33.5 to 50 cm long and 270 to 400 um wide. • Infective larvae of O. volvulus are 500 micrometers by 25 micrometers

  7. Life Cycle

  8. Monsters Inside Me • http://animal.discovery.com/videos/monsters-inside-me-worms-in-my-eye.html

  9. Pathogenesis • Adult worm is least pathogenic. • In Africa, found in pelvis region. • In Americas, it is found above the waist. • Sometimes causes enlargement of body parts and “ hanging groin” which loses elasticity in skin. • Inflammation, can spread to nearby tissues (eye) • Itchy skin • Abnormal pigmentation. • Bacterial infection

  10. Diagnosis • Blood free skin snip (biopsy) • Diagnosis is based on symptoms. • History of exposure to black flies.

  11. Treatment • Treatment and control is done by Ivermectin. • Ivermectin is effective in killing larvae, but does not affect adult worm.

  12. Control • Vector control (black fly) • Treatment of infected patients • Avoidance of black fly. • OCP “Ochocerciasis Control Program” launched in 1974. First tried larvacide on fast flowing rivers to control them. No real effect. • 1988 treatment with Ivermectin for infected people, eliminating it as public concern.

  13. Questions: • What is the definitive host of O. volvulus? • How do you diagnose O. volvulus? • What can this parasite cause? • Where is the parasite found?

  14. References: • http://www.cdfound.to.it/html/onco2.htm • http://www.brighthub.com/health/conditions-treatments/articles/20195.aspx • http://pathmicro.med.sc.edu/parasitology/nematodes.htm • http://animal.discovery.com/videos/monsters-inside-me-worms-in-my-eye.html

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