Intro to Parasitology

Match the Cestode infective from for humans with its parasite:

-Diphyllobothrium latum = Plerocoid larvae in fish -Taenia solium = Cysticercus larvae in pork -Hymenolepis nana = ova

Intestinal protozoa - Amoeba

-unicellular organisms -have two forms: a free-feeding trophozoite and an inactive cyst -The free-feeding trophozoite is amoeboid in shape, has locomotion by extension of pseudopodia, and has just one nucleus -The inactive cyst form is spherical and has 1, 2, 4, or 8 nuclei.

Chilomastix mesnili trophozoite

10 X 4

Giardia lamblia trophozoite

18 X 18

Chilomastix mesnili cyst

18 micrometers

Giardia lamblia cyst

18 micrometers

stronglyoides rhabditiform larva

220 X 15; prominent genical primodium; short buccal cavity

Trichuris ovum (looks like a football)

52 x 25

enterobius ovum (looks like a bread loaf)

60 X 25

Hookworm rabditiform larva

600 X 5; short genital primodium; long buccal cavity

Dientamoeba fragilis trophozoite

8 micrometers; 2 nuclei

ascaris ovum

86 X 40

Enterobius vermicularis

Asymmetrical ova, one side convex with the other side flattened

Acanthamoeba

Causes corneal ulcerations that can lead to blindness & Cyst stage has double-layered, polygonal walls that give clusters of cysts the appearance of a honeycomb

Acnthamoeba

Causes meningoencephalitis, which is usually fatal & Life cycle stages include: trophozoite, cyst and flagellate

Entamoeba histolytica

Cyst is 15

Iodamoeba butschlii

Cyst is 18

Blastocystis hominis

Cyst is 21

Entamoeba coli

Cyst is 35

Endolimax nana

Cyst is 5

Entamoeba hartmanni

Cyst is 7

Identify the morphological differences between cysts and trophozites

Cysts have 1, 2, 4, or 8 nuclei; are not motile; and are spherical is shape. Trophozoites have just 1 nucleus; are motile (by pseudopods); and are amoeboid in shape.

*Length of buccal cavit

For the filarial nematodes, what key characteristic of the microfilarial form is used to identify them y

size & presence/absence of ingested RBCs

How is Entamoeba hartmanni differentiated from Entamoeba histolytica?

The asexual reproduction is referred to as schizogony, which takes place in humans. The sexual reproduction is referred to as sporogony and takes place in the vector.

Humans when infected by Plasmodium serve as the intermediate host allowing the parasite to go through its asexual reproduction process. The asexual reproduction is referred to as:

Amastigote (diagnostic form in humans)

Leishmania species

Phlebotomus sand flies (vector)

Leishmania species

Promastigote (infective form for humans)

Leishmania species

Iodamoeba butschlii

Trop is 18 micrometers

Entamoeba coli

Trop is 45 micrometers

Entamoeba hartmanni

Trop is 5 micrometers

Entamoeba histolytica

Trop is 50 micrometers

Endolimax nana

Trop is 8 micrometers

FALSE, Trophozoites are very fragile and deteriorate quickly in the concentration procedure. They are best seen in a fresh specimen on the saline and iodine wet preps.

Trophozoites are recovered in concentration procedure

Tsetse fly (vector)

Trypanosoma brucei

Trypomastigote (infective form in humans)

Trypanosoma brucei (rhodesiense or gambiense)

Triatomid bug (reduvid or kssing bug) - vector

Trypanosoma cruzi

Trypomastigote (infective form in humans)

Trypanosoma cruzi

Trypomastigote (diagnostic form for humans)

Trypanosoma cruzi & brucei

Entamoeba

What genus has a nucleus that has a single karyosome located centrally or an eccentrically placed karyosome surrounded by a nuclear membrane on which is deposited a distinct ring of peripheral chromatin?

Sporozoite; The infective for of Plasmodium for humans is the sporozoite. The infective for for the vector is the gametocyte.

What is the infective form of Plasmodium for humans?

Scotch tape preparation from perianal area

What is the method of choice for demonstrating a pinworm infection?

the purposes for using the permanent stained smear in the parasitology examination of fecal specimens include all of the answers - Bring out internal structures to confirm id of protozoa, recover protozoan trophozoites, and provide a permanent record

What is/are the purpose(s) of the permanent stained smear in the parasitology examination of fecal specimens?

unidirectional motility and ingested RBCs

What key morphologic criteria is/are used to definitively identify Entamoeba histolytica trophozoites?

Stool & sputum

What specimen(s) would be useful when suspecting an Ascaris infection?

in the sediment at the bottom of the centrifuge tube

Where will you recover parasitic ova, cysts or larvae in the formalin-ethyl acetate concentration procedure?

Plasmodium malariae trophozoite

band/bar

Plasmodium falciparum gametocyte

crescent moon/banana

Strongyloides stercoralis =

filariform larae; *diagnostic form is Rhabditiform larva

Hookworm =

filariform larvae; *diagnostic form is OVA

When collecting more than one stool specimen for O&P, they must be collected at least two days apart from each other. This is to allow time for the parasites' ova and larva to be shed which often occurs at irregular time

in collecting more than one stool specimen for O&P from a patient, what time interval should be used between specimens

fecal-oral routes, sexually, via insect vectors and through penetration of the skin

in what way are parasites transmitted to humans

avoid insect bites. change dietary habits. educations

in what ways are parasitic transmissions controlled or prevented

Ascaris lumbricoides =

ova; infective & diagnostic

Trichuris trichiura =

ova; infective form & diagnostic

Enterobius vermicularis =

ova; infective from & diagnostic

Plasmodium malariae schizont

rosette pattern

Glycogen vacuole

the most prominent diagnostic feature seen in the cyst of Iodamoeba butschii is a

stain the internal structural parts of the protozoa for ease of identification

the purpose for performing the iodine wet preparation as part of the ova and parasite examination is to:

collected from the toilet bowl, contaminated with barium or urine, and greater than 24 hours old and unpreserved

unacceptable stool specimen for parasitology stduies:

1. locomotion by one or more flagella 2. having specific structures such as axostyle and undulating membran

what 2 criteria are used to identify the group of intestinal protozoa known as Flagellates

better detail of internal structure of parasites

what advantage does the iron hematoxylin stain have over the trichrome stain

Chagas' Disease

what disease doe Trypanosoma cruzi cause?

RBCs are rupturing and releasing merozoites into the bloodstream

what is taking place within the patient's blood when a malarial paroxysm occurs

Ixodes scapularis tick

what is the definitive host & vector for Babesia species?

Anopheles mosquito (female mosquito)

what is the definitive host an vector for Plasmodium

making species identification possible by optimal staining of individual parasites showing the detailed morphology of the parasite

what is the purpose o the thin blood smear preparation when testing for parasites in blood

is to examine a large quantity of blood to better detect malaria parasites in cases of light reaction (thick smear) and for the thin smear, to make is possible to definitively identify the individual parasites by optimal staining of these individual parasites showing their detailed morphology

what is the purpose of the thick blood smear preparation when testing for malaria?

possesses 2 nuclei

what is unique about the tropozoite Diientamoeba fragilis

one nucleus and internal axostyle with external undulating membrane over half of the body

what key characteristic(s) is used to identify a Trichomonas vaginalis trop

Entamoeba histolytica

what parasite is the only intestinal amoeba that is pathogenic and causes amoebic dysentery

urine, vaginal discharge, urethral discharge

what specimen(s) will you find Trichomonas vaginalis in

detect motility of protozoan trophozoites

why is it important to do a warm saline preparation of fresh stool specime