medical parasitology lab

Raed Z. Ahmed, Medical Parasitology Lab.,2012

Cryptosporidium parvumCryptosporidium parvum

Infect human and most mammals. The infective stage is oocyst containing sporozoites

measuring 4-6µ in diameter. The diagnostics stage is oocyst containing 4 sporozoites. Diagnosis:

– Detecting oocyst in stool.

– Acid-fast stain.


• The most common method of diagnosing Cryptosporidiosis is acid-fast staining methods or the Ziehl-Neelsen stain.

Cryptosporidium parvum Cryptosporidium parvum oocystoocyst


http://gut.bmj.com/content/41/6/801/F2.large.jpg

Isospora belliIsospora belli• Isosporiasis is a human intestinal disease caused by the parasite

Isospora belli.

• The coccidian parasite Isospora belli infects the epithelial cells of the small intestine, and is the least common of the three intestinal coccidia that infect humans.

• Infection causes acute, non-bloody diarrhea with crampy abdominal pain, which can last for weeks and result in malabsorption and weight loss. In immunodepressed patients, and in infants and children, the diarrhea can be severe. Eosinophilia may be present.

• Diagnosis:– Acid- fast stain


Isospora belli oocystIsospora belli oocyst


Life cycleLife cycle Raed Z. Ahmed, Medical Parasitology Lab.,2012

Trichinella spiralis Trichinella spiralis • Cause trichinosis, trichiniasis or trichinelliasis..

• Adult inhabit the small intestine of the rats, pigs and human. Both males and females lie freely in the lumen of the intestine of pigs, rats and human.

• Fertilized female only penetrate the mucosa where the larviposit, they do not lay eggs.

• Larvae is the infective stage, live encysted in the flesh of the host, and they represent the diagnostic stage.

• Human infected by eating undercooked pork containing infective encysted larvae.

• Human is dead end host.


CContinue………..ontinue………..

• Diagnosis:

– Finding larvae in the blood during migration or in muscle after encystation.

– Immunological tests.

– X- ray to detect the calcified larvae in muscle.


Trichinella spiralis larvae encysted Trichinella spiralis larvae encysted in musclein muscle


Entrobius vermicularisEntrobius vermicularis• Also named as human pin worm and seat worm, cause

oxyurdiasis.• Young and mature worms are present in small intestine (at

terminal ileum till fertilization).• Gravid females are present at lower rectum where they lay ova

at perianal region around anus (oviparous).• The female is 0.88-1.3 cm long, it has a long tapering tail

resembling 1/3 its length, its straight.• The male is shorter than female (2-5 mm) the tail is curved

strongly to ventral side, and has a single spicule.• Infective stage: Embryonated Eggs.• Definitive host: human.


Continue………Continue………

• Diagnosis:

– Egg in stool is rarely detected but adults present after purgative.

– Egg can be detected at perianal area as follow:

• N.I.H method (National Institute of Health), its based on swabbing the perianal area with a cellophane paper.

• The adhesive cellulose tape (scotch tape), better result.

• The Vaseline cloth wiping, the collected ova examined.

• Egg morphology:

– 20-50u, transparent with double walled shell, it may show one side convex and the other flat.



Entrobius vermicularis Eggs Entrobius vermicularis Eggs

http://upload.wikimedia.org/wikipedia/commons/5/5d/Eggs_of_Enterobius_vermicularis_5229_lores.jpg

Entrobius vermicularis Adult Entrobius vermicularis Adult


malefemale

Trichuris trichiura Trichuris trichiura • Its commonly called whip worm because of the shape of

this worm (anterior thin and posterior thick).

• Adult inhabit the large intestine in the caecum of man.

• The adult male smaller than female, male 3.4-4.5 cm, female 4-5 cm.

• Trichuris trichiura eggs have distinct shape. (oviparous)

• Diagnosis:

– Stool examination to detect eggs.


Trichuris trichiura EggsTrichuris trichiura Eggs


Trichuris trichiura AdultTrichuris trichiura Adult


http://upload.wikimedia.org/wikipedia/commons/a/a7/Trichuris_trichiura.jpg

Strongyloides stercoralis 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.


Strongyloides stercoralis LarvaeStrongyloides stercoralis Larvae


Rhabditiform

Filariform

S. Stercoralis Adult MaleS. Stercoralis Adult Male


spicules

spicules

S. Stercoralis Adult FemaleS. Stercoralis Adult Female


Ancylostoma duodenalae Ancylostoma duodenalae (Hookworm)(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.


Hookworm Eggs Hookworm Eggs


Hook worm eggs like insects or mites egg, therefore must be differentiated

Mites egg Hook worm eggPlant material

Hookworm LarvaeHookworm Larvae


Filariform Rhabditiform

Hookworm AdultHookworm Adult


MaleFemale

Ancylostoma duodenalae Ancylostoma duodenalae copulatry burasacopulatry burasa


Ancylostoma duodenalae buccal Ancylostoma duodenalae buccal capsule capsule


Comparison between Ancylostoma duodenalae Comparison between Ancylostoma duodenalae and Necator americanusand Necator americanus


Copulatory bursa Copulatory bursa vsvs Copulatory Copulatory SpiculesSpicules


Necator americanus copulatory spiculesAncylostoma duodenalae copulatory spicules

Comparison between S. stercoralis Comparison between S. stercoralis and Hookworm and Hookworm


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