cestodes and immunology Flashcards
common name for cestodes
tapeworms
head of tapeworm? segments?
scolex; proglottis
Why can tapeworm infection be missed if a gross fecal exam is not done
Intact proglottids are too heavy to float
What effects do tapeworms have on the host
- intestinal obstruction
- injury to intestinal mucosa (enteritis)
- interfere with absorption of nutrients
Name the genus for 5 kinds of tapeworm and tell what the definitive host species is
dipylidium (dogs and cats)
taenia (dogs and cats)
echinococcus (dogs and cats)
anaplocephala (horse)
monezia (ruminants)
Besides worming the animal, what must be done to prevent reinfection with cestodes?
control the intermediate host
intermediate host for dipylidium
fleas
intermediate host for taenia
rabbits and rodents
intermediate host for echinococcus
sheep, deer, elk, humans
intermediate host for large animal tapeworms
mites
immunology
cells from other organisms have proteins on the surface that are recognized by an animal’s immune system as not belonging to the animal’s body
antigens
proteins not wanted in the body
antibody
fit the shape of antigen to remove it
sensitivity
Ability to correctly identify all animals that are truly positive for a given reaction procedure
Specificity
Measures the number of false positives produced with a given reaction procedure
sensitivity vs specificity
- highly sensitive tests are prone to false positives
- highly specific tests are prone to false negatives
sample collection tubes
Red top- serum
Lavender- plasma unless otherwise noted
Green top- if heparinized plasma is requested
serum handling
● Clot for 20 to 30 minutes at room temperature
● Centrifuge for 10 minutes at ≤1500 rpm
plasma handling
● Centrifuge immediately after collection
* Pipette serum or plasma into a transfer tube and label
* Freeze or refrigerate for later use
ELISA
● most commonly used in vet practice
● accurate way to detect specific antigens: viruses, bacteria, parasites hormones
- test for antibody in serum: contains heart worm, feline leukemia, FIV, Parvo, progesterone
CELISA
● Uses patient antigen
● Uses enzyme-labeled antigens, as well as monoclonal antibodies
● Intensity of color varies with concentration
● equine infectious Anemia
latex agglutination
- uses small, spherical latex particles coated with an antigen suspended in water
- if serum containing the correct antibody is added, agglutination occurs
- bovine brucellosis
false negatives can occur
when excessive amounts of antigen or antibody are present
prozone phenomenon
excess antibody: it is possible that each antibody molecule binds with only one or two antibodies and does not cross-link so that agglutination does not occur
excess antigen: can result in lack of cross linking when the excess antigen surrounds any small clumps that may form
lateral flow immunoassay
● Uses colloidal gold, enzymes, and color reagents or agglutinated latex particles
● Antibodies present in the membrane of the test cassette where sample is applied.
● Positive results show two areas of color, test, and control.
immunology analyzers
● Are available for practices but are not common - Some only read test results
● Larger units are used in reference laboratories
● Can read multiple tests at once
● Many automated analyzers use the principles of chemiluminescence
Chemiluminescence
● Principle similar to the ELISA method except that the test uses a substrate that reacts to produce light
● Amount of light produced can be quantified
● Used for detection and quantification of pathogens as well as other substances
- Thyroid hormones, cortisol, pancreatic lipase, progesterone, and testosterone
Coomb’s test
detects the presence of autoantibodies
Direct Coombs’ reaction
- detects antibodies that attack RBC’s
- positive test: Immune-mediated hemolytic disease
indirect Coomb’s
- detects circulating antibodies
- positive test: antibodies against body’s own tissue
immunodiffusion
- Patient serum and antigen placed in separate wells on an agar plate
- Both diffuse through the agar and form a band of precipitation where they meet
- no band = no antibody present
- detects: equine infectious anemia and johne’s disease
Radioimmunoassay
● Mainly used in research and diagnostic laboratories.
● Similar to CELISA but uses a radioisotope instead of an enzyme.
● Antigen is labeled with a radioisotope and an antibody.
● Radioactivity is measured and compared with a standard curve to determine the concentration of antigen in the patient’s serum.
Fluorescent Antibody Testing
● Not common in veterinary practice but available in reference laboratories
● Used to verify a tentative diagnosis
- two tests: direct and indirect
- Patient sample added to a fluorescent dye- conjugated antigen
- Examined microscopically for fluorescence
Antibody Titers
● Not routinely performed
● May be needed to distinguish between active infection and prior exposure
● Used when reliable antigen test not available
● Can be used to determine need for revaccination
titer
greatest dilution at which a sample no longer yield a positive result
Molecular Diagnostics
● Analyze DNA and RNA
● Many state diagnostic laboratories offer testing
molecular diagnostics DNA tests are used to
- identify cancers
- detect genetic defects
- pedigrees
- bacterial contaminants in food
advantages to molecular diagnostics
- increased sensitivity and specificity
- small samples
- faster results
disadvantages to molecular diagnostics
- contamination gives false positives
- high levels of expertise to run tests
- high cost
Reverse Transcriptase Polymerase Chain Reaction
- similar to PCR but tests single-stranded RNA
- must first be converted to double-stranded DNA before PCR can continue
Real-Time Polymerase Chain Reaction
● Decreases the risk of contamination
● More easily automated
● Faster and easier to run
● fluorescence probe attaches to DNA segments
Polymerase Chain Reaction
● Small amount of DNA detected is amplified to better run the test and determine results.
● Three steps:
- Denaturation
- Annealing
- Extension
- Process repeated 25 to 30 times to gain enough DNA
