Onchocerciasis “River Blindness”

1. Onchocerciasis“River Blindness” http://www.unep.org/yearbook/2004/images/emergingphoto5.jpg

2. Onchocerciasis“River Blindness” Second leading infectious cause of blindness in the world http://www.unep.org/yearbook/2004/images/emergingphoto5.jpg

3. Onchocerciasis“River Blindness” Second leading infectious cause of blindness in the world http://www.unep.org/yearbook/2004/images/emergingphoto5.jpg Also causes skin lesions and skin nodules and intense itching

4. More than 30million people worldwide are infected with Onchocerciasis http://www.stanford.edu/class/humbio103/ParaSites2004/Onchocerciasis/worldmap.png

5. Transmission is concentrated in central Africa and Latin America Over 90% of all cases occur in Africa http://www.stanford.edu/class/humbio103/ParaSites2004/Onchocerciasis/worldmap.png

6. Infection caused by the parasitic worm Onchocercavolvulus Adult worms Microfilariae of O. volvulus from a skin nodule of a patient from Zambia http://www.icp.ucl.ac.be/~opperd/parasites/images/worms.jpg http://www.dpd.cdc.gov/dpdx/HTML/Filariasis.htm

7. Infection spreads from person to person by the bite of an infected Simulium blackfly WHO/TDR/Stammers

9. Human Stages 1. Infected blackfly introduces third stage larvae onto the skin of the host, then they penetrate the skin

10. Human Stages 1. Infected blackfly introduces third stage larvae onto the skin of the host, then they penetrate the skin 2. Larvae develop into adults in subcutaneous tissue

11. Human Stages 3. Adults produce microfilariae

12. Human Stages 3. Adults produce microfilariae 4. A blackfly ingests microfilariae during blood meal

13. Blackfly Stages 5. After ingestion, microfilariae migrate to the thoracic muscles of the blackfly

14. Blackfly Stages 6. There they develop into stage 1 larvae, and then stage 3 larvae 5. After ingestion, microfilariae migrate to the thoracic muscles of the blackfly

15. Blackfly Stages 7. 3rd stage larvae can infect another human when the blackfly takes a blood meal 6. There they develop into stage 1 larvae, and then stage 3 larvae 5. After ingestion, microfilariae migrate to the thoracic muscles of the blackfly

16. But…how does this cause blindness and other symptoms?

17. But…how does this cause blindness and other symptoms? As mentioned earlier, adult worms produce microfilariae in the human stages 3. Adults produce microfilariae– up to 1000 per day!

18. Microfilariae induce intense inflammatory responses, especially upon their death http://www.icp.ucl.ac.be/~opperd/parasites/onch1.html

19. Microfilariae induce intense inflammatory responses, especially upon their death Some microfilariae will migrate throughout the upper layers of the skin, causing large nodules to form under skin… http://www.icp.ucl.ac.be/~opperd/parasites/onch1.html

20. …and skin rashes and lesions, known as “leopard skin” http://www.icp.ucl.ac.be/~opperd/parasites/onch1.html

21. Others migrate to the surface of the cornea, causing sclerosing Keratitis to occur http://www.icp.ucl.ac.be/~opperd/parasites/onch1.html

22. Others migrate to the surface of the cornea, causing sclerosing Keratitis to occur The infected area becomes increasingly opaque with more microfilariae http://www.icp.ucl.ac.be/~opperd/parasites/onch1.html

23. Ivermectin is the drug of choice for Onchocerciasis • Paralyzes and kills microfilariae of O. volvulus http://3.bp.blogspot.com/-V4h6xT_GaKM/TwcIXiInfaI/AAAAAAAAuAg/Yx6UAxhqif0/s1600/Merck-%2526-Co-Logo.jpg

24. Ivermectin is the drug of choice for Onchocerciasis • Paralyzes and kills microfilariae of O. volvulus • Doesn’t kill adult females, but prevents them from producing any offspring http://3.bp.blogspot.com/-V4h6xT_GaKM/TwcIXiInfaI/AAAAAAAAuAg/Yx6UAxhqif0/s1600/Merck-%2526-Co-Logo.jpg

25. Ivermectin is the drug of choice for Onchocerciasis • Paralyzes and kills microfilariae of O. volvulus • Doesn’t kill adult females, but prevents them from producing any offspring • Thus, prevents transmission http://3.bp.blogspot.com/-V4h6xT_GaKM/TwcIXiInfaI/AAAAAAAAuAg/Yx6UAxhqif0/s1600/Merck-%2526-Co-Logo.jpg

26. Studies in hyperendemic foci have shown the effectiveness of Ivermectin

27. Has anyone done anything about this?

28. Has anyone done anything about this? Onchocerciasis Control Programme (OCP) was launched in 1974 • Launched by WHO http://www.who.int/blindness/partnerships/onchocerciasis_OCP/en/index.html

29. Goals of OCP • Control blackfly populations • Use Ivermectinto treat infected people

30. Controlling blackfly populations involved interrupting transmission by eliminating the blackfly vector http://www.icp.ucl.ac.be/~opperd/parasites/onch1.html

31. Controlling blackfly populations involved interrupting transmission by eliminating the blackfly vector Helicopters are used to spray insecticides on rivers and fast moving waters (Simulium breeding sites) http://www.icp.ucl.ac.be/~opperd/parasites/onch1.html

32. OCP was a huge success and ended in 2002 African Programme for OnchocerciasisControl (1995) OnchocerciasisElimination Programme for the Americas (1992) http://ars.els-cdn.com/content/image/1-s2.0-S1471492201021122-gr1.jpg

33. References Diawara L, Traoré MO, Badji A, Bissan Y, Doumbia K, et al. (2009) Feasibility of Onchocerciasis Elimination with Ivermectin Treatment in Endemic Foci in Africa: First Evidence from Studies in Mali and Senegal. PLoSNegl Trop Dis 3(7): e497. doi:10.1371/journal.pntd.0000497 "DPDx - Filariasis." DPDx– Filariasis. Web. 05 Nov. 2012. <http://www.dpd.cdc.gov/dpdx/HTML/Filariasis.htm>. "Onchocerciasis (River Blindness)." Stanford.edu. Web. 05 Nov. 2012. <http://www.stanford.edu/class/humbio103/ParaSites2004/Onchocerciasis/index.htm>. "Priority Eye Diseases." WHO. Web. 05 Nov. 2012. <http://www.who.int/blindness/causes/priority/en/index3.html>.