1. Schistosomiasis Neena Davisson March 15, 2012

2. Schistosomiasis is a parasitic infection
Schistosomiasis is caused by a trematode helminth

3. Schistosomiasis is an ancient disease
Schistosome eggs have been recovered from both Chinese and Egyptian mummies

4. Schistosomiasis is an ancient disease
Hieroglyphics also refer to the disease.
in the “Papyrus Ebers” (1550 BC) appear to refer to the disease, bloody urine being frequently mentioned. Middle East Assyrian records ( BC)

5. Schistosomiasis is prevalent in tropical and sub-tropical areas
Schistosomiasis is endemic to Africa, and is also found in the Far East, South America, the Caribbean, and the Middle East. The worms that cause schistosomiasis are not found in the United States.

6. Schistosomiasis is commonly found in areas without safe water and good sanitation. At-risk groups include…
Agricultural and fishing populations
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7. Schistosomiasis is commonly found in areas without safe water and good sanitation. At-risk groups include…
Agricultural and fishing populations
Women performing domestic chores
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8. Schistosomiasis is commonly found in areas without safe water and good sanitation. At-risk groups include…
Agricultural and fishing populations
Women performing domestic chores
Irrigation workers
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9. Schistosomiasis is commonly found in areas without safe water and good sanitation. At-risk groups include…
Agricultural and fishing populations
Women performing domestic chores
Irrigation workers
Refugees
“Off track” tourists
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10. …but schistosomiasis is largely a disease of children.
Children who swim and play in infested waters
School-aged children (10-14 yrs) are the highest at-risk group
Causes growth stunts, affects memory and IQ
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Urinary schistosomiasis affects 66 million children throughout 54 countries.

11. Schistosomiasis causes great morbidity and mortality in the developing world
> 200 million people are infected worldwide, 600 million at risk
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12. Schistosomiasis causes great morbidity and mortality in the developing world
> 200 million people are infected worldwide, 600 million at risk
85% of infections in sub-Saharan Africa
About 280,000 die every year from infection
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13. Schistosomiasis causes great morbidity and mortality in the developing world
> 200 million people are infected worldwide, 600 million at risk
85% of infections in sub-Saharan Africa
About 280,000 die every year from infection
Morbidity – growth stunting, cognitive impairment, hepatic fibrosis, urinary obstruction, cancer
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14. There are two forms of Schistosomiasis
Acute
Rash (Swimmer’s itch)
Fever
Cough
Chills
Muscle aches
Rash:

15. There are two forms of Schistosomiasis
Acute
Chronic
Rash (Swimmer’s itch)
Fever
Cough
Chills
Muscle aches
Abdominal pain
Ascites
Enlarged liver
Splenomegaly
Blood in stool
Diarrhea
Hematuria (blood in urine)
Dysuria (painful urination)
Varicose veins
Seizures
Paralysis
Varicose veins:
Rash:
Seizures and paralysis will only occur if the schistosome eggs reach the brain or spinal cord

16. Biopsy is the primary method of diagnosing schistosomiasis
Use fecal smears and urine tests to visualize schistosome eggs
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presence of eggs is definitive diagnosis
Children infected with schistosomiasis show vials of blood-red urine.

17. Biopsy is the primary method of diagnosing schistosomiasis
Use fecal smears and urine tests to visualize schistosome eggs
Blood in urine can be detected using chemical reagent strips
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presence of eggs is definitive diagnosis
Children infected with schistosomiasis show vials of blood-red urine.

18. Blood tests also help confirm diagnosis but…
Positive results may only indicate past exposure
Latency period 6-8 weeks since it takes time for the eggs to develop and stimulate an immune response
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19. Blood tests also help confirm diagnosis but…
Positive results may only indicate past exposure
Tests are not positive until the patient has been infected for 6-8 weeks
Latency period 6-8 weeks since it takes time for the eggs to develop and stimulate an immune response
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20. Some other diagnostic methods
For tissue biopsy in case no eggs are found in fecal or urine samples:
Colonoscopy
Endoscopy
Liver biopsy
Colonoscopy Image:

21. Some other diagnostic methods
For tissue biopsy in case no eggs are found in fecal or urine samples:
Colonoscopy
Endoscopy
Liver biopsy
To measure extent of infection:
MRI CT
Ultrasound
Chest x-rays
Echocardiograms
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MRI Image:

22. How was schistosome parasite discovered?
Theodor Bilharz
First described by Theodor Bilharz in 1851
Kasr-el-Aini hospital in Cairo
Post-mortem examination
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"After my attention had been drawn to the liver, I soon found a white long helminth in the blood of the portal vein in quantity, which I assumed to be a nematode but which I immediately recognised as something new. The microscope revealed a splendid distomum with a flat body and a curving tail which exceeded the body about ten times in length...”

23. The Life Cycle of the Schistosome relies on two hosts
Snails grow schistosome sporocysts that develop into free-swimming cercariae.
Cercariae attach to and penetrate human skin, and migrate through blood vessels to reach portal blood system.
During migration, cercariae develop into male and female adult parasitic worms which incorporate human proteins into surface structure causing little or no immune response.
Parasite mating occurs in portal blood system and eggs are produced. Eggs stimulate a strong immune response.
Some eggs migrate through bowel or bladder and are shed in feces or urine, while other eggs migrate to other tissues.
Eggs shed into urine or feces may reach maturity in freshwater and infect susceptible snails.

24. The Life Cycle of the Schistosome relies on two hosts
Intermediate host: snail
Definitive host: human
Adult stages have two sexes
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25. There are many forms of schistosomes that cause disease in humans
S. mansoni – causes intestinal schistosomiasis and is prevalent in 52 countries of Africa, the Caribbean, the Eastern Mediterranean and South America
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26. There are many forms of schistosomes that cause disease in humans
S. mansoni – causes intestinal schistosomiasis and is prevalent in 52 countries of Africa, the Caribbean, the Eastern Mediterranean and South America
S. haematobium – causes urinary schistosomiasis and affects 54 countries in Africa and Eastern Mediterranean
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27. There are many forms of schistosomes that cause disease in humans
S. mansoni – causes intestinal schistosomiasis and is prevalent in 52 countries of Africa, the Caribbean, the Eastern Mediterranean and South America
S. haematobium – causes urinary schistosomiasis and affects 54 countries in Africa and Eastern Mediterranean
S. japonicum – causes intestinal schistosomiasis in the Pacific region (aka ‘Katayama’ disease)

28. There are many forms of schistosomes that cause disease in humans
S. mansoni – causes intestinal schistosomiasis and is prevalent in 52 countries of Africa, the Caribbean, the Eastern Mediterranean and South America
S. haematobium – causes urinary schistosomiasis and affects 54 countries in Africa and Eastern Mediterranean
S. japonicum – causes intestinal schistosomiasis in the Pacific region (aka ‘Katayama’ disease)
S. mekongi – causes intestinal schistosomiasis in 7 African countries

29. There are many forms of schistosomes that cause disease in humans
S. mansoni – causes intestinal schistosomiasis and is prevalent in 52 countries of Africa, the Caribbean, the Eastern Mediterranean and South America
S. haematobium – causes urinary schistosomiasis and affects 54 countries in Africa and Eastern Mediterranean
S. japonicum – causes intestinal schistosomiasis in the Pacific region (aka ‘Katayama’ disease)
S. mekongi – causes intestinal schistosomiasis in 7 African countries
S. intercalatum - found in 10 African countries

30. Infection induces T-cell response
Increase in TNF, IL-1 and IL-6
Granuloma formation
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31. How do we treat schistosomiasis?
First line drug: Praziquantel
Treats all forms of schistosomiasis
No side effects
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32. How do we treat schistosomiasis?
First line drug: Praziquantel
Treats all forms of schistosomiasis
No side effects
Oxamniquine
Intestinal schistosomiasis
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33. How do we treat schistosomiasis?
First line drug: Praziquantel
Treats all forms of schistosomiasis
No side effects
Oxamniquine
Intestinal schistosomiasis
Metrifonate
Urinary schistosomiasis
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Neguvon = Trichlorfon = Metrifonate
This is the metrifonate used to treat cattles, horses, pigs

34. Praziquantel may target the parasite’s calcium ion channels
Mechanism and target is unknown
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Prevents newly hatched worms from growing or multiplying
Increases exposure of schistosome antigens – elicits immune response

35. Praziquantel may target the parasite’s calcium ion channels
Mechanism and target is unknown
Causes severe spasms and paralysis of worms’ muscles caused by influx of Ca2+ ions
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Prevents newly hatched worms from growing or multiplying
Increases exposure of schistosome antigens – elicits immune response

36. Praziquantel may target the parasite’s calcium ion channels
Mechanism and target is unknown
Causes severe spasms and paralysis of worms’ muscles caused by influx of Ca2+ ions
Metabolized through cytochrome p450 pathway via CYP3A4
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Prevents newly hatched worms from growing or multiplying
Increases exposure of schistosome antigens – elicits immune response

37. Praziquantel has many limitations
Ineffective against juvenile schistosomes
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38. Praziquantel has many limitations
Ineffective against juvenile schistosomes
Develops resistance
Resistant strains in Egypt and Senegal
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Resistance to S. japonicum

39. Praziquantel has many limitations
Ineffective against juvenile schistosomes
Develops resistance
Resistant strains in Egypt and Senegal
High rates of reinfection
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Resistance to S. japonicum

40. Praziquantel has many limitations
Ineffective against juvenile schistosomes
Develops resistance
Resistant strains in Egypt and Senegal
High rates of reinfection
Cannot be taken by HIV/AIDS patients on Rifampin (inhibits CYP3A4)
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41. Part of the treatment plan needs to include prevention strategies
Health education/hygiene
Installation of safe water supply
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42. Part of the treatment plan needs to include prevention strategies
Health education/hygiene
Installation of safe water supply
Treatment of water supply with molluscicides
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43. Part of the treatment plan needs to include prevention strategies
Health education/hygiene
Installation of safe water supply
Treatment of water supply with molluscicides
Vaccine – not yet developed
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44. Works Cited
Griffiths, Jeffrey. "MPH/CEE241 Biology of Water and Health, Fall Tufts OpenCourseWare." Tufts University, Web. 2 Mar
"Parasites - Schistosomiasis." Centers for Disease Control and Prevention, 02 Nov Web. 2 Mar
Pearce, Edward J., and Andrew S. MacDonald. "The Immunobiology of Schistosomiasis."Nature Reviews 2 (2002): Web. 2 Mar
"Schistosomiasis." MicrobiologyBytes, 28 Jan Web. 2 Mar
"Schistosomiasis." World Health Organization, Jan Web. 2 Mar
Stewart, Terry. "SRG Introduction to Schistosomiasis." University of Cambridge: Department of Pathology, Web. 2 Mar