practical parasitology collected and prepared by: wael al laithi

Practical Parasitology

Collected and prepared by:Wael Al Laithi

The Life Cycle of Giardia Lamblia

Giardia lamblia The cysts, are oval measuring from 11 to 14 µm in length and 7 to 10 µm in width. Four nuclei are usually visible along with axonemes, and median bodies. Often, the cyst will appear shrunken, pulling away from the cyst wall

Giardia lamblia The trophozoites are described as having a 'tear-drop' shape and are 18 µm long and 10 µm wide. The trophozoites contain two nuclei, four pair of flagella, two axonemes, and two curved bodies called the median bodies.

Entamoeba histolytica Life cycle

the cysts can survive days to weeks in the external environment and are responsible for transmission

Trophozoites passed in the stool are rapidly destroyed once outside the body

Entamoeba histolytica

CYST 10 – 15 µMtrophozoite15 to 20  µm.

cyst will have 1 to 4 nuclei. In addition, the peripheral chromatin is generally evenly distributed.

Nematoda

Ascaris Lumbricoidesz

Ascariasis is a disease caused by Ascaris Lumbricoides, an intestinal roundworm known as a nematode

Ascaris lumbricoides life cycle

Female 50 cm

Male 30 cm

Ascaris Fertilized, decorticated eggs

size 45 - 85 microns

Fertilized, corticated eggs Ascaris

Ascaris unfertilized or otherwise non-viable eggs

Egg size(infertile): 78 - 105 microns in length Both fertile and infertile ova can be corticated or smooth

The life cycle of Enterobius vermicularis

Female 8-13 mm

Male 2-5mm

Eggs of the human pinworm Enterobius vermicularis

Egg size 50-60 µm by 20-32 µm

Egg size: 52 - 58 microns

Rhabditiform larva length: 250 microns

Filariform larva: 550 microns

3 or 4 days to filariform 2-5

days

Strongyloides stercoralis life cycle

Rhabditiform larva of Strongyloides stercoralis.  100x

larvae hatch in 1 to 2 days. 

after 5 to 10 days

infective larvae can survive 3 to 4 weeks in favorable environmental conditions

Hookworm Ancylostoma braziliense] [Ancylostoma caninum] [Ancylostoma duodenale] [Necator americanus]

Necator americanus : 5 to 11 millimetres , 90 percent of human hookworm infections that occur in tropical and subtropical regions of the world

A. braziliense, from 8 to 11 millimetres long, is normally parasitic in dogs and cats; man, however, is sometimes infected by this species in the southern United States, South America, and Asia.

Hookwormfilariform larva

Rhabditiform larvae that hatch from eggs are 250-300 µm long and approximately 15-20 µm wide.

Hookworm filariform larva

Hookworm eggs in unstained wet mounts, taken at 400× magnification

60-75 µm by 35-40 µm.

Ancylostoma duodenale

Copulatory bursa

Plasmodium

Anopheles mosquito

Schizont: Hepatic Stage

Recognizing Erythrocytic Stages:Schematic Morphology

TROPHOZOITERING

SCHIZONT GAMETOCYTE

Plasmodium falciparum

Rings: double chromatin dots; appliqué forms;multiple infections in same red cell

Gametocytes: mature (M)andimmature (I) forms (I is rarelyseen in peripheral blood)

Trophozoites: compact(rarely seen in

peripheral blood)

Schizonts: 8-24 merozoites(rarely seen in peripheral blood)

M I

Plasmodium vivax

Trophozoites: ameboid; deforms the erythrocyte

Gametocytes: round-oval Schizonts: 12-24 merozoites

Rings

Infected erythrocytes: enlarged up to 2X; deformed; (Schüffner’s dots)

Plasmodium ovaleInfected erythrocytes: moderately enlarged (11/4 X); fimbriated; oval; (Schüffner’s dots) “malariae - like parasite in vivax - like erythrocyte”

Rings

Trophozoites: compact

Schizonts: 6-14 merozoites; dark pigment; (“rosettes”)

Gametocytes: round-oval

Infected erythrocytes: size normal to decreased (3/4X)

Plasmodium malariae

Trophozoite:compact

Trophozoite:typical band form

Schizont:6-12 merozoites;coarse, dark pigment

Gametocyte:round; coarse,dark pigment

Species Differentiation on Thin FilmsFeature 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 spots

Schuffner spots

none

Trophozoite shape small ring, appliqu

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

6-12 merzoites

Gametocyte crescent shape large, round

large, round

compact, round

Species Differentiation on Thin Films

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

Rings

Trophozoites

Schizonts

Gametocytes

Morphology

Malarial parasite trophozoites are generally ring shaped, 1-2 microns in size, although other forms (ameboid and band) may also exist.

The sexual forms of the parasite (gametocytes) are much larger and 7-14 microns in size.

P. falciparum is the largest and is banana shaped, while others are smaller and round.

Morphology

Ring form:

(Plasmodium vivax )

a ring of bluish cytoplasm with

a dot-like nucleus

Trophzoite of Plasmodium vivax

irregular cytoplasm and enlarged nucleus with malarial pigment

( hemozoin)

Schizont of P.vivax

multiple masses of nuclear chromatin

Gametocytes

Male gametocyte Female gametocyte

Note: compact cytoplasm and absence of nuclear division.

Ring form of P. falciparum

Ring with double nuclei Multiple infections

African sleep sickness Trypanosoma brucei gambiense

Tsetse Fly

Trypanosoma Diagnosis

African Trypanosomiasis in Travelers Returning to the United Kingdom

1- Detection of trypanosoma chancre after bite

The Tsetse bite is usually painful and may develop into a red sore called a chancre

2- Blood smear within 21 days from the bit , it will show the parasite

A blood smear from a patient with African trypanosomiasis. a centrally located nucleus, an undulating membrane, and an anterior flagellum. The two Trypanosoma brucei species that cause human trypanosomiasis, T. b. gambiense and T. b. rhodesiense, are undistinguishable morphologically. The trypanosomes length range is 14-33 µm

Trypanosoma brucei gambiense

trypomastigote

Taenia life cycle

An egg of Taenia pisiformis

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The scolex of T. solium has hooks on its anterior end, while the scolex of T. saginata only has the four suckers.

Cercariae are about 1 mm in length

S.haematobium S. Mansoni egg

terminal spine

A lateral spine

Hymenolepis nana

القزمة الشريطية الدودة

The scolex has four suckers and an armed rostellum.

Hymenolepis nana: midll part of gravid progllottids (One of the segments of a tapeworm, containing both male and female reproductive organs )

1 cm long

Hymenolepsis nana. An egg of H. nana, with its characteristic double membrane.

50 µm, ovoid

Trichuris trichiura (whipworm)

eggs become infective in 15 to 30 days

The adult worms (approximately 4 cm in length)

1000 to 7000 eggs per day

Trichuris trichiura (whipworm )

The female measures 35 - 50mm long and the male 30 - 45 mm long.  ova with bipolar plugs.  They

measure 50 - 54m by 20 - 23m.

Trichinella spiralis

Larva in the skeletal muscle

Practical Diagnostic Parasitology

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