Introduction to Parasitology and Laboratory Procedures

Which stool preservative is best for very long-term storage and preservation of ova and parasites:

Which stool preservative is best for very long-term storage and preservation of ova and parasites:

10% formalin

Which of the following may interfere with finding O&Ps in stool specimens?

tetracycline

Charcot-Leyden crystals are occasionally observed in stool. These crystals are probably from breakdown products of:

Eosinophils

Which of the following is not a part of the macroscopic (naked eye) examination of a stool specimen for ova & parasites?

presence of yeast

Where are O&Ps located in a stool specimen that has been concentrated with formalin ethyl acetate?

in the bottom sediment

The physician suspects that a patient is infected with amoebae; how is the specimen best stored?

mix a sample of the specimen with PVA

Wet preps of stool specimens should be scanned using the _____ objective of the microscope.

10x

Which stool preservative cannot be used if a trichrome smear is required?

Formalin

where asexual reproduction occurs

intermediate host

capable of entering the host

infective stage

where sexual reproduction occurs

definitive host

recognized as host's parasite

infective stage

Adult

Location of the parasite stage in a
human host

Diagnostic Stage

The means by which parasite
stages leave the human

Infective Stage

When the parasite is infective

Method of Infection

The means by which a new
human host is infected (e.g., egg is ingested).

What do a tech need to know about each parasite

The scientific name
 The common name
 The location of the adults in humans
 The diagnostic stage and body specimen of
choice for examination
 The method of infection of humans
 Other specific information pertinent to the
diagnosis of each parasitic infection

The association of two different species of organisms exhibiting metabolic dependence by their relationship

symbiosis

The association of two different species of organisms in which each individual benefits from the activity of the other. Similar interactions within a species are known as cooperation

mutualism

The association of two different species of organisms in which one partner is benefited and the other is neither benefited nor injured.

commensalism. 

The association of two different species of organisms in which the smaller species lives on or within the other and has a metabolic dependence on the larger host species.

parasitism

What are some reason to reject A STOOL SPECIMEN

§Antibiotics

§Barium enemas

§Mineral oils

§Bismuths

§Antidiarrheals

§Anti-malarial drugs

•Urine contamination

•More than one specimen collected on same day

§10% Buffered Formalin

•good for eggs, larvae, cysts

•excellent for long-term storage:

•may distort protozoan forms

•stool in formalin cannot be used to make trichrome smears

§PVA (Polyvinyl Alcohol)

•Preserves all O & P forms (ova, cysts & trophs, larvae)

•Best for trichrome smear preparation

§SAF (Sodium Acetate-Acetic Acid-Formalin)

•Preserves all O & P forms

•Very good for  trichrome smears

•Environmentally safer than PVA