Schistosomiasis neena davisson march 15 2012
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Schistosomiasis Neena Davisson March 15, 2012. Schistosomiasis is a parasitic infection. Schistosomiasis is caused by a trematode helminth. Schistosomiasis is an ancient disease. Schistosome eggs have been recovered from both Chinese and Egyptian mummies.

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Schistosomiasis neena davisson march 15 2012

SchistosomiasisNeena DavissonMarch 15, 2012


Schistosomiasis is a parasitic infection

Schistosomiasis is a parasitic infection

  • Schistosomiasis is caused by a trematodehelminth


Schistosomiasis is an ancient disease

Schistosomiasis is an ancient disease

Schistosome eggs have been recovered from both Chinese and Egyptian mummies


Schistosomiasis is an ancient disease1

Schistosomiasis is an ancient disease

Hieroglyphics also refer to the disease.


Schistosomiasis is prevalent in tropical and sub tropical areas

Schistosomiasis is prevalent in tropical and sub-tropical areas


Schistosomiasis neena davisson march 15 2012

Schistosomiasis is commonly found in areas without safe water and good sanitation. At-risk groups include…

  • Agricultural and fishing populations


Schistosomiasis neena davisson march 15 2012

Schistosomiasis is commonly found in areas without safe water and good sanitation. At-risk groups include…

  • Agricultural and fishing populations

  • Women performing domestic chores


Schistosomiasis neena davisson march 15 2012

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


Schistosomiasis neena davisson march 15 2012

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


But schistosomiasis is largely a disease of children

…but schistosomiasis is largely a disease of children.

Urinary schistosomiasis affects 66 million children throughout 54 countries.


Schistosomiasis causes great morbidity and mortality in the developing world

Schistosomiasis causes great morbidity and mortality in the developing world

  • > 200 million people are infected worldwide, 600 million at risk


Schistosomiasis causes great morbidity and mortality in the developing world1

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


Schistosomiasis causes great morbidity and mortality in the developing world2

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


There are two forms of schistosomiasis

There are two forms of Schistosomiasis

Acute

  • Rash (Swimmer’s itch)

  • Fever

  • Cough

  • Chills

  • Muscle aches


There are two forms of schistosomiasis1

There are two forms of Schistosomiasis

Acute

Chronic

Abdominal pain

Ascites

Enlarged liver

Splenomegaly

Blood in stool

Diarrhea

Hematuria (blood in urine)

Dysuria (painful urination)

Varicose veins

Seizures

Paralysis

  • Rash (Swimmer’s itch)

  • Fever

  • Cough

  • Chills

  • Muscle aches


Biopsy is the primary method of diagnosing schistosomiasis

Biopsy is the primary method of diagnosing schistosomiasis

  • Use fecal smears and urine tests to visualize schistosome eggs

Children infected with schistosomiasis show vials of blood-red urine.


Biopsy is the primary method of diagnosing schistosomiasis1

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

Children infected with schistosomiasis show vials of blood-red urine.


Blood tests also help confirm diagnosis but

Blood tests also help confirm diagnosis but…

  • Positive results may only indicate past exposure


Blood tests also help confirm diagnosis but1

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


Some other diagnostic methods

Some other diagnostic methods

  • For tissue biopsy in case no eggs are found in fecal or urine samples:

    • Colonoscopy

    • Endoscopy

    • Liver biopsy


Some other diagnostic methods1

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


How was schistosome parasite discovered

How was schistosome parasite discovered?

Theodor Bilharz

1825-1862

"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...”


The life cycle of the schistosome relies on two hosts

The Life Cycle of the Schistosomerelies on two hosts


The life cycle of the schistosome relies on two hosts1

The Life Cycle of the Schistosome relies on two hosts

  • Intermediate host: snail

  • Definitive host: human

  • Adult stages have two sexes


There are many forms of schistosomes that cause disease in humans

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


There are many forms of schistosomes that cause disease in humans1

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


There are many forms of schistosomes that cause disease in humans2

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)


There are many forms of schistosomes that cause disease in humans3

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


There are many forms of schistosomes that cause disease in humans4

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


Infection induces t cell response

Infection induces T-cell response

  • Increase in TNF, IL-1 and IL-6

  • Granuloma formation


How do we treat schistosomiasis

How do we treat schistosomiasis?

  • First line drug: Praziquantel

    • Treats all forms of schistosomiasis

    • No side effects


How do we treat schistosomiasis1

How do we treat schistosomiasis?

  • First line drug: Praziquantel

    • Treats all forms of schistosomiasis

    • No side effects

  • Oxamniquine

    • Intestinal schistosomiasis


How do we treat schistosomiasis2

How do we treat schistosomiasis?

  • First line drug: Praziquantel

    • Treats all forms of schistosomiasis

    • No side effects

  • Oxamniquine

    • Intestinal schistosomiasis

  • Metrifonate

    • Urinary schistosomiasis


Praziquantel may target the parasite s calcium ion channels

Praziquantel may target the parasite’s calcium ion channels

  • Mechanism and target is unknown


Praziquantel may target the parasite s calcium ion channels1

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


Praziquantel may target the parasite s calcium ion channels2

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


Praziquantel has many limitations

Praziquantel has many limitations

  • Ineffective against juvenile schistosomes


Praziquantel has many limitations1

Praziquantel has many limitations

  • Ineffective against juvenile schistosomes

  • Develops resistance

    • Resistant strains in Egypt and Senegal

Resistance to S. japonicum


Praziquantel has many limitations2

Praziquantel has many limitations

  • Ineffective against juvenile schistosomes

  • Develops resistance

    • Resistant strains in Egypt and Senegal

  • High rates of reinfection

Resistance to S. japonicum


Praziquantel has many limitations3

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)


Part of the treatment plan needs to include prevention strategies

Part of the treatment plan needs to include prevention strategies

  • Health education/hygiene

  • Installation of safe water supply


Part of the treatment plan needs to include prevention strategies1

Part of the treatment plan needs to include prevention strategies

  • Health education/hygiene

  • Installation of safe water supply

  • Treatment of water supply with molluscicides


Part of the treatment plan needs to include prevention strategies2

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


Works cited

Works Cited

  • Griffiths, Jeffrey. "MPH/CEE241 Biology of Water and Health, Fall 2007 - Tufts OpenCourseWare." Tufts University, 2008. Web. 2 Mar. 2012. http://ocw.tufts.edu/Content/55/lecturenotes/703050/703095

  • "Parasites - Schistosomiasis." Centers for Disease Control and Prevention, 02 Nov. 2010. Web. 2 Mar. 2012. http://www.cdc.gov/parasites/schistosomiasis/biology.html

  • Pearce, Edward J., and Andrew S. MacDonald. "The Immunobiology of Schistosomiasis."Nature Reviews 2 (2002): 499-511. 2002. Web. 2 Mar. 2012.

  • "Schistosomiasis." MicrobiologyBytes, 28 Jan. 2007. Web. 2 Mar. 2012. http://www.microbiologybytes.com/introduction/Schisto.html

  • "Schistosomiasis." World Health Organization, Jan. 2012. Web. 2 Mar. 2012. http://www.who.int/mediacentre/factsheets/fs115/en/

  • Stewart, Terry. "SRG Introduction to Schistosomiasis." University of Cambridge: Department of Pathology, 2010. Web. 2 Mar. 2012. http://www.path.cam.ac.uk/~schisto/schistosoma/index.html


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