Schistosomiasis (Snail Fever)

http://www.youtube.com/watch?v=1CQdd39Lq1g

• Humans acquire schistosomiasis by direct contact with the larval stages (known as cercariae) that swim in freshwaterSpecies of flatworm

Length as adult

Disease Percentage of cases

worldwide

Major geographic locations

Schistosoma haematobium

.4-.8 inches Urogenital schistosomiasis

63% Africa, Middle East

Schistosoma mansoni

.2-.7 inches Intestinal and hepatic (in the

liver) schistosomiasis

35% Africa, Middle East, Americas

Schistosoma japonicum and

Schistosoma mekongi

.5-1 inch Intestinal and hepatic

schistosomiasis

1% China, the Philippines,

Southeast Asia

Where Schistosomiasis Occurs

• Poor rural populations – People whose everyday activities involve fishing, bathing,

or swimmining in schistosome-contaminated water or working in agricultural areas irrigated by contaminated waters are at the highest risk of infection

Discussion

• Suppose you are the primary bread winner in your household and were recently infected with Snail Fever. You fish 12 hours a day to provide for your family and are barely getting by.– Would you tell your family you have Snail Fever?– Would you keep working your job?– Would you seek medical attention?

Effects of Schistosomiasis• Schistome eggs become

trapped: – bladder – reproductive organs– Intestines– Liver

• Results in:– mechanical damage– ruptured blood vessels– Bleeding– inflammatory response

(obstructs urine and blood flow)

Effects of Schistosomiasis Continued

• The schistosomes can live for years in the veins of the bladder and intestine

• Constant egg release chronic blood loss anemia

• Long-standing anemia, inflammation, and organ damage: – Growth retardation– Undernutrition– Cognitive delays– Chronic abdominal pain– Exercise intolerance– Poor school performance– Reduced work capacity

Discussion

• How do some of the long term health effects of Snail Fever that we discussed (anemia, kidney failure, liver disease) have an impact on the quality of life of those affected individuals, their families, communities and the surrounding communities?

• What effects would you expect to be seen psychologically? Economically?

Schistosomiasis and HIV/AIDS

FGS causes genital lesions, increasing risk of contracting HIV/AIDS 3-4 foldAfrica’s lowest cost AIDS prevention strategy = fighting FGS with praziquantel

Praziquantel• Most effective means of controlling

schistosome infections • Launched in the 90s in Brazil, China,

Egypt, Morocco, the Phillipines, Saudi Arabia, Tunisia, and Puerto Rico– Disease is close to being eliminated

(zero transmission) in Morocco and Puerto Rico

• Leads to:– improvements in growth and physical

fitness– Anemia reductions– Can reverse urinary and liver disease

Controlling Schistosomiasis• In 2010, only 33 million of the 236 of children at risk for schistosomiasis received

praziquantel Bill & Melinda Gates partnered with major pharmaceutical companies and world agencies in the London Declaration in 2012– Reaffirmed support for mass drug administration

Schistosomiasis Control Initiative (SCI):

• Founded in 2002 from the Gates Foundation and USAID• Helps map prevalence of the disease, formulation of a strategy

plan, and requesting and obtaining praziquantel

Discussion

• Do you think a global drug administration of praziquantel will end Snail Fever? Why or why not?

• Is there another approach we should take to end these infections?

• WHO PSA https://www.youtube.com/watch?v=2u_qPN8lR98

Living With Schistosomiasishttp://www.youtube.com/watch?v=5wQbpgAdIMs