Disease Name: Schistosomiasis (‘Bilharziasis’)
Key Points:
Infection occurs when skin comes into contact with contaminated
fresh water in which snail vectors are living
3 main parasite species: S. haematobium (urogenital), S. japonicum
& S. mansoni (intestinal)
Distribution Statistics
Africa (S. mansoni, S. intercalatum, S. Estimated 200,000 deaths globally in 2000
haematobium) At least 290.8 million people require
Asia (S. japonicum, S. mekongi) preventative treatment in 2018, out of which
South America (S. mansoni) 97.2 million were treated
Life Cycle
1. Eggs released from human’s hatch & release miracidia into water which
penetrate snail intermediate hosts
2. Cercariae are produced in the snail which are released into water to
penetrate the skin of the human host when swimming/bathing/fishing
3. Cercariae lose their tails during penetration & become schistosomulae
4. Migrate via venous circulation to the lungs, heart & then develop in the liver
into adults
5. Adults exit the liver via the portal vein system, where male and female
worms copulate & reside in the mesenteric venules (species specific)
6. Females deposit eggs in the small venules of the portal/perivesical systems
7. Eggs move towards intestine or bladder/ureters (species specific) & are
eliminated from the body, often re-contaminating the water
Signs & Symptoms Diagnosis
Haematuria (blood in urine), blood in stool Faecal microscopy (faecal smear or kato-katz
Hepatosplenomegaly, growth stunting method)
Chronic infection can lead to liver fibrosis or Urine filtration for S. haematobium
bladder cancer Serology
Lateral flow test (CCA urine for S. mansoni)
Rectal/bladder snip
Treatment & Control
Treatment with praziquantel (impacts adult
worms only, have to retreat)
Mass drug administration of at-risk
populations to stop the spread of infection
Environmental control – molluscicides
Improved water, sanitation, & hygiene
Health education – reduce amount of people
coming into contact with infected water
https://www.stuvia.co.uk/user/kennedyella
Key Points:
Infection occurs when skin comes into contact with contaminated
fresh water in which snail vectors are living
3 main parasite species: S. haematobium (urogenital), S. japonicum
& S. mansoni (intestinal)
Distribution Statistics
Africa (S. mansoni, S. intercalatum, S. Estimated 200,000 deaths globally in 2000
haematobium) At least 290.8 million people require
Asia (S. japonicum, S. mekongi) preventative treatment in 2018, out of which
South America (S. mansoni) 97.2 million were treated
Life Cycle
1. Eggs released from human’s hatch & release miracidia into water which
penetrate snail intermediate hosts
2. Cercariae are produced in the snail which are released into water to
penetrate the skin of the human host when swimming/bathing/fishing
3. Cercariae lose their tails during penetration & become schistosomulae
4. Migrate via venous circulation to the lungs, heart & then develop in the liver
into adults
5. Adults exit the liver via the portal vein system, where male and female
worms copulate & reside in the mesenteric venules (species specific)
6. Females deposit eggs in the small venules of the portal/perivesical systems
7. Eggs move towards intestine or bladder/ureters (species specific) & are
eliminated from the body, often re-contaminating the water
Signs & Symptoms Diagnosis
Haematuria (blood in urine), blood in stool Faecal microscopy (faecal smear or kato-katz
Hepatosplenomegaly, growth stunting method)
Chronic infection can lead to liver fibrosis or Urine filtration for S. haematobium
bladder cancer Serology
Lateral flow test (CCA urine for S. mansoni)
Rectal/bladder snip
Treatment & Control
Treatment with praziquantel (impacts adult
worms only, have to retreat)
Mass drug administration of at-risk
populations to stop the spread of infection
Environmental control – molluscicides
Improved water, sanitation, & hygiene
Health education – reduce amount of people
coming into contact with infected water
https://www.stuvia.co.uk/user/kennedyella
