Intestinal Nematodes

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Strongyloides stercoralis

• Intestinal Nematodes

Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Life cycle
Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Strongyloides stercoralis

• Adults lives in the small intestine (duodenum and
  jejunum), fertilized females are deeply embedded
  in the mucosa, where they also oviposit.
• Male have a pointed curved tail associated with
  two spicules.
• Female have straight tail without spicules.
• In contrast to the Anclystoma spp., both sexes
  have short buccal cavity.
• Infective stage Filariform larvae.
• Diagnosis
• Based on recovery of the rhabditiform larvae
  passed in stool.
• If diarrhea is present, eggs may also be
  recovered.

Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Strongyloides stercoralis Larvae
Rhabditiform
Filariform
Raed Z. Ahmed, Medical Parasitology Lab.,2012
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S. Stercoralis Adult Male
spicules
spicules
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S. Stercoralis Adult Female
Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Ancylostoma duodenale

• Intestinal Nematodes

Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Life cycle
Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Ancylostoma duodenalae (Hookworm)

• Inhabit human intestine ( jejunum, ileum, and
  rarely duodenum ) and cause Anclystomiasis.
• Male shorter than female and have copulatory
  bursa and two spicules.
• Female is long and has pointed end.
• Both sexes have long buccal cavity with two pairs
  of teeth.
• Infective stage Filariform larvae.
• Diagnosis
• Based on finding ova in fresh stool sample.
• In old sample, larvae present and must be
  differentiated from larvae of Strongyloides
  stercoralis.

Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Hookworm Eggs
Hook worm eggs like insects or mites egg,
therefore must be differentiated
Mites egg
Hook worm egg
Plant material
Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Hookworm Larvae
Filariform
Rhabditiform
Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Hookworm Adult
Female
Male
Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Ancylostoma duodenalae copulatry burasa
Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Ancylostoma duodenalae buccal capsule
Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Comparison between Ancylostoma duodenalae and
Necator americanus
Ancylostoma duodenalae Necator americanus
Old world hookworm New world hookworm
Larger (male 8-11mm) Smaller (male 7-9mm)
Prominent buccal capsule with 2 pairs of teeth Smaller buccal capsule with 2 pairs of semilunar cutting plates
Copulatory spicules not fused Copulatory spicules fused at ends to form a barbed tip
Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Copulatory bursa vs Copulatory Spicules
Necator americanus copulatory spicules
Ancylostoma duodenalae copulatory spicules
Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Comparison between S. stercoralis and Hookworm
Aspect Anclystoma spp. (Hook worm) Strongyloides stercoralis
Rhabditiform larvae Rhabditiform larvae
Buccal cavity Long Short
Esophagus One third of the body One third of the body
Genital permordium Absence Prominent
Filariform larvae Filariform larvae
Esophagus One third of the body Half of the body
Tail Pointed Notched
larvae Striated sheath Unsheathed
Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Ascaris lumbricoides

• Intestinal Nematodes

Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Ascaris lumbricoides

• Ascaris lumbricoides is the giant roundworm of
  human, inhabit small intestine and cause
  Ascariasis .
• There are three diagnostic stages for Ascaris
  lumbricoides
• Fertilized eggs.
• Unfertilized eggs..
• Adult
• Male has a coiled posterior end, 2 minute
  spicules and no copulatory bursa 15-30 cm in
  length.
• Female oviparous have straight, pointed tail and
  no spicules. (lay 200,000 eggs daily) 20-40 cm
  in length.
• Infective stage Embryonated eggs.

Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Ascaris lumbricoides Ova

• Diagnosis
• Stool analysis to detect unfertilized eggs,
  fertilized eggs or adult.
• There are 3 shapes of ova
• Embryonated egg
• Corticated and Decorticated
• Fertilized egg
• Corticated and Decorticated
• Unfertilized egg
• Corticated and Decorticated

Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Ascaris lumbricoides Adult
Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Ascaris lumbricoides Unfertilized Egg
Corticated
Decorticated
Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Ascaris lumbricoides Fertilized Egg
Corticated
Decorticated
Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Ascaris lumbricoides Embryonated Egg
Corticated
Decorticated
Raed Z. Ahmed, Medical Parasitology Lab.,2012
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Ascaris Lumbricoides Larvae
Raed Z. Ahmed, Medical Parasitology Lab.,2012