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

Fertilized, corticated eggs Ascaris

Ascaris Fertilized, decorticated eggs

size 45 - 85 microns

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 8-13mm

Male 2-5mm

Eggs of the human pinworm

Enterobius vermicularis

Egg size 50-60 µm by 20-32 µm

Strongyloides stercoralis life cycle

Egg size: 52 - 58 microns

Rhabditiform larva length: 250 microns

Filariform larva: 550 microns

3 or 4days to filariform

2-5 days

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

Ancylostoma duodenale, 8 to 13 millimeters long, is found on all continents but is most prevalent in warm regions.

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.

Hookworm

filariform 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 StageSchizont: 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)

Infected erythrocytes: normal size

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 FilmsSpecies 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 FilmsSpecies Differentiation on Thin Films

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

Rings

Trophozoites

Schizonts

Gametocytes

MorphologyMorphology

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

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

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

MorphologyMorphology

Ring form:Ring form:

((Plasmodium vivaxPlasmodium vivax ) )

a ring of bluish a ring of bluish cytoplasm with cytoplasm with

a dot-like nucleusa dot-like nucleus

Trophzoite of Trophzoite of Plasmodium vivaxPlasmodium vivax

irregular irregular cytoplasm and cytoplasm and enlarged enlarged nucleus with nucleus with malarial pigmentmalarial pigment

( hemozoin)( hemozoin)

Schizont ofSchizont of P.vivax P.vivax

multiple masses of multiple masses of nuclear chromatinnuclear chromatin

GametocytesGametocytes

Male gametocyte Female gametocyte

Note: compact cytoplasm and absence of nuclear division.

Ring form of Ring form of P. falciparumP. 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 Trypanosoma brucei gambiensegambiense

trypomastigotetrypomastigote