Schistosoma

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Schistosoma

• General character
• Morphology
• Reproduction system
• Importance

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Morphology

• Size - Female 12 to 26 mm
• - Male 6 to 22 mm

The three main species infecting humans are
Schistosoma haematobium, S. japonicum , and S.
mansoni.  Two other species, more localized
geographically, are S. mekongi and S.
intercalatum
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Adult an larve of Sch.
Schistosomulum
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Geographic Distribution

• Schistosoma mansoni is found in parts of South
  America and the Caribbean, Africa, and the Middle
  East
• S. haematobium in Africa and the Middle East and
• S. japonicum in the Far East.
• Schistosoma mekongi and S. intercalatum are found
  focally in Southeast Asia and central West
  Africa, respectively.

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Life Cycle
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Miracidium Cercaria
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Liver worm
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Clinical Features

• Many infections are asymptomatic. 
• Swimmers itch ( Cercarial Dermatitis)
• Acute schistosomiasis (Katayama's fever) may
  occur weeks after the initial infection,
  especially by S. mansoni and S. japonicum.
• .  Manifestations include fever, cough, abdominal
  pain, diarrhea, hepatospenomegaly, and
  eosinophilia.
•   Occasionally central nervous system lesions
  occur
• cerebral granulomatous disease may be caused by
  ectopic S. japonicum eggs in the brain, and
  granulomatous lesions around ectopic eggs in the
  spinal cord from S. mansoni and S. haematobium
  infections.

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Schistosoma egg
                                                                                        

• JK

Sch.mansoni egg
Sch. japonicum egg
Sch. Haematobium egg
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Epidemiology of Schistomiasis
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Intermediate host
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Cercarial Dermatitis
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Immuno-pathologic consequences

• Continuing infection may cause granulomatous
  reactions and fibrosis in the affected organs,
  which may result in manifestations that include
• colonic polyposis with bloody diarrhea(Schistosom
  a mansoni mostly)
• portal hypertension with hematemesis and
  splenomegaly(S. mansoni, S. japonicum,)
• cystitis and ureteritis (S. haematobium) with
  hematuria, which can progress to bladder cancer
• pulmonary hypertension (S. mansoni, S.
  japonicum, more rarely S. haematobium)
  glomerulonephritis and central nervous system
  lesions

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Hepatomegaly splenomegaly
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Granuloma( Sch. japonicum egg)
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Granuloma( Sch. hematobium egg)
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Granuloma
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Laboratory Diagnosis

• Microscopic identification of eggs in stool or
  urine is the most practical method for diagnosis.
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• Stool examination should be performed when
  infection with S. mansoni or S. japonicum is
  suspected,
• and urine examination should be performed if S.
  haematobium is suspected.

Tissue biopsy (rectal biopsy for all species and
biopsy of the bladder for S. haematobium) may
demonstrate eggs when stool or urine examinations
are negative.
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Antibody detection

• Antibody detection can be useful to indicate
  schistosome infection in patients who have
  traveled in schistosomiasis endemic areas and in
  whom eggs cannot be demonstrated in fecal or
  urine specimens.

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Treatment

• Safe and effective drugs are available for the
  treatment of schistosomiasis. 
• The drug of choice is praziquantel for infections
  caused by all Schistosoma species. 
• Oxamniquine has been effective in treating
  infections caused by S. mansoni in some areas in
  which praziquantel is less effective. 

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