MTAP 1 PARASITOLOGY (PROTOZOAN)

INTESTINAL AMOEBA

Unicellular, microscopic parasites.

Trophozoites and Cyst

______ and ______ stages are part of the amoeba life cycle

CYST

_____ infective stage

Trophozoites

________ is the active reproductive stage

Excystation

development of a cyst into a trophozoite

Encystation

development of a trophozoite into a cyst

Entamoeba histolytica

-The only pathogenic ameoba for the GIT.

-Can also affect the liver (amoebic liver abscess) & the CNS.

Entamoeba histolytica

Cyst are quadrinucleated, with fine, evenly distributed peripheral chromatin pattern and centrally located karyosome. Cigar-shaped chromatoidal bars are found in the cytoplasm

Entamoeba histolytica

Trophozoites are motile via means of pseudopods, exhibiting unidirectional, progressive motility. It is uninucleated with finely granular cytoplasm which contains RBC inclusions

colitis and liver abscess.

(E. histolytica) Most invasive amoeba and only one known to cause ___ and ___

Entamoeba coli

Cysts are nucleated, with up to eight (8) nuclei. It has large, eccentrically located karyosome, with unevenly distributed chromatin pattern. Cytoplasm contains chromatoidal bars with splinter-ends.

Entamoeba coli

Trophozoites are motile via pseudopods exhibiting non-progressive motility. They contain single nucleus and coarse cytoplasm.

Blastocystis hominis

Currently classified as round with large central body that pushes nuclei near the periphery.

5 or more per 400x field

(Blastocystis hominis) Should be reported esp. when numerous______

-Entamoeba coli

-Blastocystis hominis

NON-PATHOGENIC AMOEBA

-Endolimax nana

-Entamoeba gingivalis

-Iodamoeba butschlii

-Entamoeba hartmanni

Other Non-pathogenic Amoeba:

ENDOLIMAX NANA

smallest amoeba to infect humans

Entamoeba gingivalis

causes asymptomatic mouth and genital tract infections; has NO CYST form.

Iodamoeba butschlii

characterized by large, iodine- staining glycogen vacuole.

Entamoeba hartmanni:

similar to E. histolytica in terms of appearance; can be differentiated thru the size (E. hartmanni is smaller than E. histolytica); small race amoeba

FLAGELLATES

-Uses flagella for motility

-Can be found intestinally or extra-intestinally (in the blood or tissue).

GARDIA

is the ONLY PATHOGENIC intestinal flagellate. Typically associated with mild to moderate diarrhea which can lead to malabsorption and steatorrhea.

Giardia lamblia

(a.k.a. G. duodenalis and G. intestinalis)

Giardia lamblia

CYST: Non-motile, non- feeding and infective stage; presence of four (4) nuclei

Giardia lamblia

Trophozoite has the typical old man with eye glasses appearance; possessing four (4) pairs of flagella, exhibiting the falling leaf motility.

ENTERO-STRING TEST

______ for duodenal material may also be performed.(G. LAMBLIA)

Balantidium coli

Largest protozoan to infect humans

-large, kidney bean macronucleus

-smaller, round micronucleus.

(Balantidium coli) Double walled cyst contains 2 nuclei:

-Stool exam

-FECT

-Sheather’s sugar flotation

DX for Cryptosporidium parvum

Cyclospora cayetanensis

-clinically significant species

-Produces non-bloody diarrhea but usually asymptomatic.

-Acid-fast oocyst

-Oocyst is passed unsporulated

humans

Cystoisospora belli definitive host

-Direct wet mount

-Concentration methods

DX for Cystoisospora belli

Plasmodium falciparum

causes the most severe form of malaria (blackwater fever)

-P. vivax

-P. falciparum

-P. malariae

-P. ovale

-P. knowlesi

5 major species causes malaria:

Plasmodium falciparum & Plasmodium vivax

Majority of the infection in the Philippines are caused by ____ and___

SPOROGONY

the sexual phase that occurs within the intestinal tract of mosquito.

SCHIZOGONY

the asexual phase that occurs in the human host; schizogony consists of the pre-erythrocytic, erythrocytic and the gametogonic cycle.

finger stick

Blood should be collected by_______ and blood smears made immediately

EDTA

_______can be used as an anticoagulant in a venipuncture.

THICK smear preparation

a drop of blood is placed on a glass microscope slide and allowed to air dry. The RBCs are lysed (LAKING) in distilled water & the material is stained with Giemsa.

THIN smear preparation

a drop of blood is placed on a glass microscope slide & the blood is spread out on the slide using another slide. The smear is fixed in METHANOL to prevent RBC lysis & then stained.

Every 36 hours

-P. falciparum

_______ malignant tertian malaria______

Every 48 hours

-P. ovale

______ ovale malaria_____

Every 48 hours

-P. vivax

_______ benign tertian malaria_______

Every 72 hours

-P. malariae

_______quartan malaria_______

TROPHOZOITES OR RING FORMS

-Demonstrated using Giemsa or Wright’s stain.

-Found in RBCs; intracellular ring-like in appearance (blue cytoplasmic ring connected to a red chromatin dot).

SCHIZONTS = merozoites

-Presence of numerous pigmented granules that are reddish brown in color.

-Increase in size of parasite due to active chromatin activity (gene regulation).

-Schizonts contain merozoites, the number & arrangement depend on the species.

GAMETOCYTES = pink to purple

-Presence of chromatin mass that appears pink to purple.

-Gametocytes are usually round to oval in shape; however P. falciparum gametocytes are characteristically crescent or banana-shaped.

Babesia microti

Transmission is thru bite of a deer tick (Ixodes scapularis) – the same vector of the Lyme disease agent (Borrelia burgdorferi).

Babesia microti

similar to P. falciparum; 2 to 4 rings per RBC are often seen, sometimes appearing like a “maltese cross” or as tetrads.

cats

D.H of Toxoplasma gondii

-Pregnant women

-lamb and pork

(Toxoplasma gondii) ______are usually at risk o Transmission is thru ingestion of undercooked meat ____ and _____ containing viable tissue cysts.

Toxoplasma gondii

Tachyzoites (trophozoites) are crescent to round in shape.

Toxoplasma gondii

Cysts contain many bradyzoites.

Naegleria fowleri

-Can cause primary amoebic meningoencephalitis (PAM), which is often fatal within 3-6 days.

-Found as free-living parasites in lakes, ponds and swimming pools where the water is warm.

cyst, trophozoite, flagellate

Forms of Naegleria fowleri

Acanthamoeba

Can cause granulomatous amoebic encephalitis (GAE) and amoebic keratitis (cornea infection), especially associated with the use of contaminated cleaning solution for contact lenses

cyst & trophozoite

Morphology of Acanthamoeba

Trichomonas vaginalis

-Causes vaginitis in women; men however, are generally asymptomatic carriers.

-Sexually transmitted disease and can infect neonates (aspiration pneumonia) during delivery.

Trichomonas vaginalis

TROPHOZOITE:Have jerky motile, with an undulating membrane & are pear shaped.

3 to 5 anterior and 1 posterior

(Trichomonas vaginalis) FLAGELLA: _____ and ______

-amastigote

-promastigote

-epimastigote

-trypomastigote.

Hemoflagellates 4 stages of development:

AMASTIGOTE

non-flagellated ova form, found in tissue.

PROMASTIGOTE

flagellated stage found in the vector, rarely seen in the blood.

EPIMASTIGOTE

long, slender, flagellated form found in arthropod vectors.

TRYPOMASTIGOTE

has an undulating membrane running the length of the body; found both in the vector & bloodstream of humans.

Africa & S. America

Trypanosomiasis occurs mainly in ____ and _____ not found in the Philippines.

T. brucei

causes trypanosomiasis or sleeping sickness which affects the lymphatic system & CNS; typical signs include swollen lymph nodes at the posterior base of the neck (Winterbottom’s sign);

TSE TSE FLY

T. brucei vector

gambiense & rhodensiense

T. brucei 2 major subspecies

Trypanosoma cruzi

-Causes Chagas disease or American trypanosomiasis.

-Associated with the formation of lesions known as CHAGOMA, conjunctivitis, edema of the face and legs and heart muscle involvement leading to myocarditis.

kissing bug (Triatomine bug)

Trypanosoma cruzi Transmitted by the bite of____

-liver

-spleen

-reticuloendothelial involvement.

Disseminated leishmaniasis:

sandfly

Leishmania vector

-Africa

-Eastern Europe

-South/Central America

(Leishmania)Mainly a disease of ____,____, and ____