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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 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.

slide6
Schistosomiasis is commonly found in areas without safe water and good sanitation. At-risk groups include…
  • Agricultural and fishing populations
slide7
Schistosomiasis is commonly found in areas without safe water and good sanitation. At-risk groups include…
  • Agricultural and fishing populations
  • Women performing domestic chores
slide8
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
slide9
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 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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