Parasitology Module 4

what is modified acid-fast stain used for?

visualization of cryptosporidium

Macroscopic vs. Microscopic

• Observe characterisitcs of feces (visible mucus, blood, adult worms), age of specimen

• direct wet mounts, concentration of specimens, permanent stains

4 methods for analyzing stool specimens

direct wet mounts, concentration techniques, permanent stains, rapid screening tests

how should a stool specimen be stored

• room temp. if used within an hour

• refrigerated if used in couple hours to overnight

how to use a weighted pharmaceutical capsule

one end of capsule is swallowed, goes down the digestive system, pull back up with the other end of the capsule, mucus is left on the string and used for testing

how many stool specimens are needed for exams?

3

unacceptable stool specimens:

containing water, urine, oil laxatives, barium, antibiotics

2 preservatives for stool

PVA & 5% formalin

container used for specimen

sterile container with tight fitting top or screw top lid

2 enemies of stool specimens

time and temperature

2 most important criteria for a satisfactory stool specimens

quality and freshness

what type of stool specimens do we need?

one saline laxative and one normally passed specimen

Diagnostic stages of protozoa

Cysts and trophozoites

Diagnostic stages of Helminths

Ova, larvae, proglottids

What is a hydatid cyst?

How does it relate to immunohematology?

bladder filled with fluid that becomes the size of a grapefruit

the fluid contains P1 antigen and used to neutralize with anti-P1 antibody

Fish tapeworm

almond shaped scolex, two slit grooves called bothria, uterus is rosette shaped, broad proglottid,

ingested by copepod

what role does cysticercoid play in life cycle of dwarf tapeworm?

attached to mucosal wall of intestine to develop into strobilia

Pork tapeworm Vs. Beef tapeworm

• Taenia solium; armed; gravid proglattids are flabby and inactive

• Taenia Sagata; unarmed

• Both are attached to intestinal wall and contain ova in proglattids

unarmed Vs. armed rostellum

• lacks hooks that attach to intestinal wall

• contains hooks for attachment

why do tapeworms not need a digestive system?

already in a pool of digested food that is absorbed and used for nourishment

anatomical regions of tapeworms

scolex (suction cups), neck, proglottids

what phylum and class do tapeworms belong?

why are they called tapeworms?

Phylum Platyhelminthes; Class Cestoda

flat shaped and resemble a tape measure

why are schistosomes called “blood flukes”?

name 3 species:

located in blood vessels

shistosoma mansoni, schistosoma japonicum, schistosoma haematobium (found in urine)

what flukes are confused with tuberculosis

Paragonimus westermani

what are two liver flukes?

Fasciola hepatica and Clonorchis sinensis

what are the largest fluke found in humans?

how is it diagnosed?

Fasciolosis buski

finding operculated ova in feces

immature stages of flukes:

egg, miracidium, sporocyst, redia, cercaria, metacercaria

flukes are in what phylum and class?

Phylum platyhelminths; Class digenea/ trematoda