Parasitology

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Parasitology
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Classification
Parasitology
Protozology
Helminthology
Entomology
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Helminthology
Platyhelminthes (Flat worms)
Nematohelminthes (Round worms)
Trematoda (Flukes)
Nematoda
Ceastoda (Tape worms)
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Trematodes of medical importance in our course
Heterophyes heterophyes
Fasciola hepatica Fasciola gigantica
Schistosoma haematobium Schistosoma mansoni
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Schistosoma haematobium Schistosoma mansoni
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Name Schistosoma haematobium Schistosoma mansoni Schistosoma mansoni
Definition- Blood Flukes (Bilharzia) Blood Flukes (Bilharzia) Blood Flukes (Bilharzia)
Distribution Egypt, Africa middle east Egypt, Africa middle east Africa, Latin America portirico.
Disease Urinary Schistosomiasis Urinary Schistosomiasis Intestinal Schistosomiasis
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Unlike trematodes

• Schistosoma has only one intermediate host.
• No reservoir.
• Schistosoma eggs not operculated.
• Forked tail cercaria.
• Cylindrical worm.
• It is the only trematode in which sex is
  separated while other trematodes are
  hermaphrodite.

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Habitat
Definitive host
Intermediate host
Reservoir
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Schistosoma haematobium Schistosoma mansoni
Habitat Urogenital veins (vesical plexus) Mesenteric veins (mesenteric plexus)
Definitive host Human Human
Intermediate host Snail (Bulinus truncatus) Snail (Biomphlaria alexandria)
Reservoir No reservoir No reservoir
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Diagnostic Stage
Infective Stage
Mode of infection
Treatment
Prevention
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Schistosoma haematobium Schistosoma mansoni
Diagnostic Stage Eggs in urine Eggs in stool
Infective Stage Cercaria swimming in fresh water, a forked tail cercaria Cercaria swimming in fresh water, a forked tail cercaria
Mode of infection Cercaria penetrates human skin upon exposure to fresh water containing cercaria. It causes itching at site of penetration. After 2-3 weeks of infection, fever, chills and diarrhoea occurs due to presence of the Schistosoma larva in blood, which migrate to the liver venules. Cercaria penetrates human skin upon exposure to fresh water containing cercaria. It causes itching at site of penetration. After 2-3 weeks of infection, fever, chills and diarrhoea occurs due to presence of the Schistosoma larva in blood, which migrate to the liver venules.
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Schistosoma haematobium Schistosoma mansoni
Treatment Praziquantel (Distocide ,Biltricide) Metrifonate Praziquantel (Distocide ,Biltricide) Metrifonate
Prevention Proper disposal of human sewage and elimination of snail hosts. Proper disposal of human sewage and elimination of snail hosts.
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Schistosomiasis

• Most cases are a symptomatic.
• Symptoms-
• Urinary Schistosomiasis
• haematouria (blood in
  urine).
• Intestinal Schistosomiasis
• gastrointestinal bleeding.
• General complications of chronic Schistosomiasis
  are due to the presence of Schistosoma eggs in
  tissues of spleen, gut wall or urinary bladder
  walls.

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• Egg inflammation granuloma
• fibrosis, hepatomegaly portal
  hypertension
• Portal hypertension speelnomegaly
• ascitis oesophageal varicose.
• S. haematobium eggs in bladder walls
• fibrosis, increase the frequency of bacterial
  infections bladder carcinoma or
  sterility.

No damage in hepatocytes
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• S. mansoni eggs in bladder walls secrete
• proteolytic enzymes damage to the
  distal colon.
• Mortality due to Schistosomiasis occur due to
  bleeding from ruptured oesophageal varicose which
  treated by injection of Sodium Valporate.

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Adult worm
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Schistosoma Couple
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Diagnostic Stage

• Schistosoma haematobium -
• - Eggs found in urine of urinary
  Schistosomiasis
• patients.
• - Oval egg with terminal spine.

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Diagnostic Stage

• Schistosoma mansoni-
• - Eggs found in stool of intestinal
  Schistosomiasis
• patients.
• - Oval egg with lateral spine.

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Infective Stage

• Schistosoma cercaria (forked tail).
• Found in fresh water.
• Penetrate the skin of human upon contact with
  water containing it.

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Intermediate host

• Schistosoma haematobium Bulinus truncatus
• Schistosoma mansoni Biomphlaria
  alexandria

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Drugs used in elimination of worms(Praziquantel)

• It is drug of choice for all Trematodes
  Cestodes except Fasciola species hydated sand.
• The nervous system of Trematodes and Cestodes is
  not completely studied. However Praziquantel was
  found to increase the calcium ion influx inside
  the worm muscle causing prolonged spasms for the
  worm leading to spastic paralysis death of the
  worm.
• This action not observed on Nematodes, insects or
  mammalians.

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• Praziquantel is very safe, taken as a single or
  divided dose according to the worm type.
• Dose is calculated according to the patient
  weight.
• Praziquantel is swallowed, not chewed as it is
  very bitter in taste.

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• Praziquantel is very safe, taken as a single or
  divided dose according to the worm type.
• Dose is calculated according to the patient
  weight.
• Praziquantel is swallowed, not chewed as it is
  very bitter in taste.