r. z. ahmed, medical parasitology lab., 2011 parasites endoparasitic helminthes platy helminthes...

MEDICAL PARASITOLOGY LAB.

REVISION

R. Z. Ahmed, Medical Parasitology Lab., 2011

Parasites

Endoparasitic Helminthes

Platy helminthes

(Flat worm)

Trematoda(Flukes)

Cestoda(Tape worm)

Nematode(Round worm)

Protozoa

Protozoao Classification of protozoa according to final habitat in man:

Intestinal and urogenital parasites:

E.g.: Entamoeba histolytica, Giardia lambilia, Trichomonas

vaginalis, Balantidium coli.

Blood and Tissue parasites:

E.g.: Toxoplasma gondii, Tryponasma spp., leishmania spp.,

Plasmodium spp..


Nematode o Classification of nematode according to the final habitat in

the man:

Intestinal nematode:

E.g.: Ascaris lumbricoides, Enterobius vermicularis,

Anclystoma duodenalae, Trichuris trichiura, and

Strongyloides stercoralis.

Tissue nematode:

E.g.: Wucheraria bancrofti, Trichinella spiralis, and Loa

loa.


Trematodao Also name as Flukes.

o Classification of Trematoda according to the final habitat in

man:

Liver flukes ( liver or bile ducts ):

E.g.: Fasciola spp.

Intestinal flukes :

E.g.: Hetrophyes hetrophes.

Blood flukes:

E.g.: Schistosoma spp.


Intestinal Protozoa

1. Entamoeba histolytica/ dispar

o E. histolytica inhabit large intestine and cause amoebic

dysentery.

o There is two diagnostic stages for E. histolytica/ dispar:

1. Cyst ( infective stage ).

2. Trophozoite ( motile form, motility by pseudopodia ).

o Diagnosis:

Stool examination to see cyst stage, or trophozoite stage if

the sample is fresh.


E. histolytica/disparCyst

Iodine Wet mount


E. histolytica/dispar

Trophozoite


Intestinal Protozoa

2. Giardia Lamblia

o It is the most common flagellate of the intestinal tract that

cause giardiasis .

o There is two diagnostic stages for Giardia lamblia :

1. Cyst ( infective stage ).

2. Trophozoite ( motile form, motility by flagella ).

o Diagnosis:

Stool examination to see cyst stage, or trophozoite stage if

the sample is fresh.


G. lamblia Cyst


G. lamblia Trophozoite


Urogenital Protozoa3. Trichomonas vaginalis

o Its pathogenic, inhabit the urogenital system.

o There is no cyst stage but only have trophozoite stage:

o Trophozoite is the infective and diagnostic stage and motile by

flagella.

o Diagnosis:

- Female: finding trophozoite in vaginal discharge.

- Male: finding organism in urethral prostatic discharge.


T. Vaginalis trophozoite


Intestinal Protozoa4. Cryptosporidium

parvumo Infect human and most mammals.

o There is one diagnostic stage for Cryptosporidium parvum:

Oocyst have 4 sporozoites.

o Infective stage: Oocyst containing sporozoites.

o Diagnosis:

Detecting oocyst in stool.

Staining with Acid – fast stain.


C. parvum oocyst


Tissue Protozoa5. Toxoplasma gnodii

o Habitat: reticulo-endothelial system, monocyte, and

muscle fiber and cause toxoplasmosis.

o There are two diagnostic stages for Toxoplasma gondii:

1. Cyst

2. Oocyst have 4 tachyzoites .

o Infective stage: Oocyst.

o Intermediate host: Human.

o Definitive host: Cat.


T. gondii tachyzoites



Blood Parasites

Blood Parasite

Plasmodium

Plasmodium falciparum

Plasmodium vivax

Plasmodiumovale

Plasmodium malariae

Microfilariae

Trypanosoma

Leishmania

Blood Protozoa6. Trypanosoma spp.

o T. cruci (Americans) cause Chaga’s disease.

o T. bruci (Africans) cause sleeping sickness disease.

o have many stages:

Amastigote, Promastigote, Trypomastigote, and Epimastigote.

o Intermediate host: Tse tse fly.

o Definitive host: Human.

o Infective stage: Metacyclic trypomastigote.

o Diagnostic stage: Trypomastigote.

o Diagnosis:Blood smear within 21 days from the bite, it will show the

parasites. R. Z. Ahmed, Medical Parasitology Lab., 2011

Trypanosoma


Blood protozoa

o There is many species affect man: L. tropica : cause skin lesion ( cutaneous ) L. braziliense : cause muco-cutaneous lesion. L. donovani : cause visceral lesion.

o Have two stages: Amastigote ( Leishmania stage ), in man (reticuloendothelial

cell). Promastigote ( Leptomonas stage ), the infective stage and

present in the lumen gut of the sand fly. o Intermediate host: Sand fly.o Definitive host: Human.o Diagnosis:

- Thick and thin blood film.- Skin scraping.

7. Leishmania spp.


Leishmania promastigote


Blood Protozoa

o Four species of Plasmodium are the causative agent of

malaria, these are:

P. vivax, P. malariae, P. falciparum, and P. ovale.

o Intermediate host: Human.

o Definitive host: Anopheles mosquitoes.

o Plasmodium spp. have 4 stages:

Ring form (young trophozoite.), Late ( old ) trophozoite,

Schizonts, and Gametocyte.

o Infective stage: Sporozoites.

o Diagnosis: Thick and stained thin blood film to detect parasites.

8. Plasmodium spp.


Ring form

P. vivax P. ovale

P. malariae P. falciparum

Trophozoite form

P. vivax P. ovale


Schizonts form

P. vivax P. ovale


Gametocyte form

P. vivax P. ovale


Comparison


Thick smear Thin smear

Lysed RBCs, many layer Fixed RBCs, single layer

0.25 μl blood/100 fields ( large volume )

0.005 μl blood/100 fields ( small volume )

Good screening test ( positive or negative )

Good species differentiation

Save time Requires more time to read

Low density infection can be detected as blood elements more concentrate ( more sensitive )

Low density infections can be missed

More difficult to diagnose species

Good species differentiation

Species differentiation on thin films

Feature P. falciparum P. vivax P. ovale P. malariae

Enlarged infected RBC

+ +

Infected RBC shape round round, distorted

oval, fimbriated

round

Stippling infected RBC

Mauer clefts Schuffner's spots

Schuffner's dots

none

Trophozoite shape small ring, applique

large ring, amoeboid

large ring, compact

small ring, compact

Chromatin dot often double single large single

Mature schizont rare, 12-30 merozoites

12-24 merozoites

4-12 merozoites( scattered )

6-12 merozoites

( rosette )

Gametocyte crescent shape

large, round large, round compact, round

Nematode1. Ascaris lumbricoides

o Ascaris lumbricoides is the giant roundworm of human, inhabit

small intestine and cause Ascariasis .

o There are three diagnostic stages for Ascaris lumbricoides :

1. Eggs (embryonated, fertilized, and unfertilized).

2. Larvae.

3. Adult:

Male: have 2 minute spicules and copulatory bursa.

Female: pointed tail and have no spicules.

o Infective stage: Embryonated eggs.

o Diagnosis: Stool analysis to detect egg or larvae.


Adult Stage

50 cm

30 cm


Ova or eggso There are 3 shapes of ova:

1. Embryonated egg:

Corticated.

Decorticated.

2. Fertilized egg:

Corticated.

Decorticated.

3. Unfertilized egg:

Corticated.

Decorticated.


Embryonated egg

Corticated Decorticated


http://tmcr.usuhs.mil/tmcr/chapter10/large10/10-02C.jpg

Fertilized eggs



Unfertilized eggs



Larvae stage


Nematode

o Other names: human pin worm and seat worm.

o Young and mature worms are present in small intestine (at

terminal ileum till fertilization).

o Gravid females are present at lower rectum where they lay ova at

perianal region around anus.

o Infective stage: Eggs.

o Diagnosis:

- Egg in stool is rarely detected but adults present after

purgative.

- Egg can be detected at perianal area by using scotch tape test.

2. Enterobius vermicularis


E. vermicularis adult


E. vermicularis eggs


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

Nematode

o Inhabit human intestine ( jejunum, ileum, and rarely duodenum )

and cause Anclystomiasis.

o Male shorter than female and have copulatory bursa and two

spicules.

o Female is long and has pointed end.

o Both sexes have long buccal cavity with two pairs of teeth.

o Infective stage: Filariform larvae.

o Diagnosis:

- Based on finding ova in fresh stool sample.

- In old sample, larvae present and must be differentiated from

larvae of Strongyloides stercoralis .

3. Anclystoma duodenalae ( Hook worm )


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

differentiated.

Mites egg Hook worm egg


Plant material

Anclystoma adult

MaleFemale


Anclystoma larvae


Filariform Rhabditiform

Anclystoma male copulatory bursa


Anclystoma buccal capsule


Nematode

o Adults lives in the small intestine ( duodenum and jejunum ).

o Male have a pointed curved tail associated with two spicules.

o Female have strait tail without spicules.

o In contrast to the Anclystoma spp., both sexes have short

buccal cavity.

o Infective stage: Filariform larvae.

o Diagnosis:

- Based on recovery of the rhabditiform larvae passed in

stool.

- If diarrhea is present, eggs may also be recovered.

4. Strongyloides stercoralis


S. stercoralis larvae


Rhabditiform

Filariform

S. stercoralis adult male

spicules

spicules


S. stercoralis adult female


Aspect Anclystoma spp. (Hook worm)

Strongyloides stercoralis

Rhabditiform larvae

Buccal cavity Long Short

Esophagus One – third of the body

One – third of the body

Genital permordium Absence Prominent

Filariform larvae

Esophagus One – third of the body

Half of the body

Tail Pointed Notched

larvae Striated sheath Unsheathed


Comparison

Nematode

o Adult inhabit the large intestine and cause trichuriasis.

o Adult male is smaller than female.

o Trichuris trichiura eggs have distinct shape.

o Because of the shape of this worm ( anterior thin and

posterior thick ) called whip worm.


o Diagnosis:

Detection of eggs in the stool.

5. Trichuris trichiura ( whip worm )


T. trichiura egg


T. trichiura adult


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

http://www.google.ps/imgres?imgurl=http://www.biolib.cz/IMG/GAL/17331.jpg&imgrefurl=http://www.biolib.cz/en/image/dir0/id17331/?viewall=1&termflt=3546&usg=__vbcv6KyTtpTGiwUBbbqOPtf8GUM=&h=479&w=521&sz=28&hl=ar&start=7&zoom=1&tbnid=QhVrQ804bzqKVM:&tbnh=120&tbnw=131&prev=/images?q=trichuris+trichiura&um=1&hl=ar&lr=&safe=active&sa=N&tbs=isch:1&um=1&itbs=1

Nematode

o Adult inhabit the small intestine of the rats and pigs. Both

males and females lie freely in the lumen of the intestine of

pigs and rats.

o Fertilized female only penetrate the mucosa where the

larviposit, they do not lay eggs.

o Larvae is the infective stage, live encysted in the flesh of the

host, and they represent the infective stage.

o Diagnosis:

- By finding the adult parasites in early days of infection.

- Finding larvae in the blood during migration or in muscle

after encystation.

6. Trichinella spiralis


T. spiralis larvae encysted in muscle


Cestoda1. Hymenolepis nana ( Dwarf tape worm )

o Larvae inhabit the small intestine so, there is no intermediate

host.

o This is the smallest tape worm in man.

o Eggs have double membrane and contain six hooked

oncosphere.


o Diagnosis:

Stool examination to detect the eggs.


H. nana adult


H. nana eggs


H. nana scolex


Cestoda

o There are two species that infect man and cause Taeniasis.

Taenia saginata ( Beef tape worm ).

Taenia solium ( Pork tape worm ).

o Both have mature, immature and gravid segments.

o Both have scolex provided with four cup- shaped suckers.

o In both species the infective stage is the cysticercus.

o Intermediate host:

T. saginata: Cows.

T. solium: Pigs.

o Definitive host: Human.

3. Taenia spp.


Taenia spp.o Taenia saginata and Taenia solium must be differentiated from

each other by the following:

Mature segment, gravid proglotid and adult worm.

o Diagnosis:

By finding gravid proglotid or eggs in stool.

• Direct fecal smear.

• Brine flotation technique.

• Cellophane - tape technique.


Comparison


Aspect Taenia saginata Taenia solium

Adult size Longer ( 4 – 8 meters ) Smaller ( 2 - 4 meters )

Number of segment

1000 – 2000 700 - 1000

Mature segment

Pass singly by their own activity

Pass in chain

Gravid proglotid

With 15 – 30 uterine branches With 7 – 13 uterine branches

Scolex Devoid rostellum and hooks With rostellum and 2 rows of hooks

Larvae Cysticercus bovis in cattle only Cysticercus cellulosae in pig as well as in man

Eggs


We can’t use egg to differentiate to species for each other


Scolex

Taenia soliumTaenia saginata


Mature segment


Gravid proglotid




Adult worm


Trematodao Also name as Flukes.

o Classification of Trematoda according to the final habitat in

man:

Liver flukes ( liver or bile ducts ):

E.g.: Fasciola hepatica.

Intestinal flukes :

E.g.: Hetrophyes hetrophes.

Blood flukes:

E.g.: Schistosoma spp.


Blood flukes

o Eggs are non operculated, but spined.

o Cercaria has a bifid tail and penetrate intact skin.

o Cause human bilharziasis.

o There are three species:

Schistosoma mansoni, cause intestinal bilharziasis.

Schistosoma jabonicum, cause intestinal bilharziasis.

Schistosoma haematobium, cause schistosomal hematuria

or urinary bilharziasis.

o Infective stage in three species is the Cercaria.

o Intermediate host: Snail.

o Definitive host: HumanR. Z. Ahmed, Medical Parasitology Lab.,

2011

Schistosoma spp.

Schistosoma spp.


o Habitat:

S. mansoni lives in the mesenteric venules of large intestine

and produce eggs in stool.

S. jabonicum lives in the mesenteric venules of small

intestine and produce eggs in stool.

S. haematobium lives in the venous plexus of the urinary

bladder and produce eggs in urine.

o Diagnosis:

- Stool analysis should be performed to find eggs when

infection with S. mansoni or S. jabonicum is suspected.

- Urine analysis should be performed to find eggs when

infection with S. haematobium is suspected.

Snail


Snails Schistosome species

Bulinus spp. S.haematobium

Biomphalaria spp. S.mansoni

Oncomelania spp. S.japonicum

Schistosoma egg


S. jabonicumS. haematobiumS. mansoni

Lateral spine

Terminal spine Rounded spine

Schistosoma Cercaria


Schistosoma adult male


Schistosoma adult female


Schistosomal miracidium


Snail


Oncomelania spp.Biomphalaria spp.

Bulinus spp.

Liver flukes


Fasciola spp.

o Fasciola hepatica lives in the liver of man.

o Fasciola spp. have many stages:

Oval eggs have miracidium, cercaria, metcercaria, larvae

and adult stage.

o Intermediate host: Snail.

o Definitive host: Sheep.

o Infective stage (human): Metacercaria.

o Human infected by ingestion metacercaria from infected

sheep.

o Diagnosis:

Stool analysis to find Fasciola egg.

F. hepatica egg



F. hepatica miracidium


F. hepatica larvae


Medical entomologyo Lice

o Flea

o Bed bug

o Ticks

Hard ticks

Soft ticks

o Mite


Lice

Lice egg


Flea


Ticks


Ticks

Soft ticks Hard ticks


Tick mouth part


Mite

Mite egg


Bed bug


THE END

r. z. ahmed, medical parasitology lab., 2011 parasites endoparasitic helminthes platy helminthes...

Documents

o trophozoite

medical parasitology

o habitat

o diagnosis

o infective stage

o classification of

trophozoite stage

o classification of