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organisms living together
- symbiosis that is mutually beneficial
- no disadvantage to either party
one party draws benefit from relationship but neither party is harmed
one party draws benefit (parasite) and the other is harmed (host)
parasite in/on animal
What is the difference between a facultative and an obligate parasite?
- facultative parasite: may or may not be parasitic
- obligate parasite: always parasitic (can only exist as a parasite)
What is a patent infection?
reproducing adults (female reproducing eggs)
Define prepatent period.
time from parasite entry until reproduction occurs
Define incubation period.
time from infection to disease
What's the difference between the prepatent period and the incubation period?
prepatent is before infection and incubation is from infection to time of disease
To be successful, a parasite must do what?
- gain entry to host
- avoid destruction and avoid destroying the host
- progeny gain entry to next host
List 5 ways a parasite can gain entry to a host.
- skin penetration
- inoculated by vector
How do parasites cause disease?
- cellular or tissue destruction
- interfere with blood supply
- mechanical obstruction
- competition for nutrients
- irritation to the host
- competition for nutrients
- irritation to the host
- transmission of disease
- host hypersensitivities
- ingestion of host's blood
- secondary infections
- external parasites
- live on the host
- internal parasites
- live in the host
What is helminthe?
flatworms and roundworms
Define definitive host.
host in which the parasite reaches reproductive stage
Define intermediate host.
- some parasites require a host for part of the life cycle
- for development of intermediate/larval stages
What's the difference between biological and mechanical vectors?
- biological vector: parasite uses vector for life cycle changes
- mechanical vector: no life cycle changes go on and the vector is just used to transport the parasite
What is paratenic (transport) host?
- carries immature parasite
- no development occurs
- host may spread it over distances
What is an incidental or aberrant host?
unnatural, may/may not be hurt
What is meant by the term "reservoir"?
wildlife hosts that make eradication and control difficult
What's the difference between direct and indirect life cycles?
- direct: parasite needs only one host
- indirect: intermediate host required (requires more than one host)
What are different ways to test for the presence of parasites?
- fecal exam
- gross exam
- microscopic exam
- direct smear
- concentration methods (flotation and sedimentation)
The gross fecal exam includes description of what things?
- presence of blood
- presence of mucus
What is the difference between hematochezia and melena?
- they are different types of blood present in feces
- hematochezia: red and from colon
- melena: black, tarry and from upper GI tract
Where does mucus in stool come from?
How do you perform a direct smear?
- mix small amount feces with saline
- look for protozoa, larvae, and ova
- stain smear
How do you perfom a passive floatation?
- mix feces and solution in cup, test tube, kit container
- pour through strainer
- add floatation solution to just over top (meniscus)
- place cover slip on top
How do you perform a centrifugal sedimentation?
- mix feces with water (filters out debris)
- centrifuge for 3 - 5 minutes
- slowly pour off supernatant
- pipette from top of sediment
- place on slide
- add cover slip
How do you use a Baermann Apparatus?
- wrap feces in gauze
- hold gauze in water with stick
- keep in water for several days
- the larvae will sink
How do you perform a centrifugal and floatation
- mix feces and solution in a cup, test tube, or kit container
- pour thru screen into test tube
- centrifuge for 3 - 5 minutes at 1500 rpms
- fill to top with more floatation solution
- lay cover slip over top of tube
- examine in 10 minutes - the ova will have floated to the cover slip
What is the time requirement for floating in saturated sugar solution?
20 - 30 minutes
What is the time requirement for floating in zinc sulfate solution?
10 - 15 minutes
What is the time requirement for floating in sodium nitrate solution?
10 - 15 minutes
What are the advantages to using saturated sugar solution?
- readily available ingredients
- doesn't distort worm ova
- long shelf life
- doe not crystalize
What are the disadvantages to using saturated sugar solution?
- sticky and messy
- ova rise slowly (20 - 30 minutes)
- may get a false negative
- may distort larvae and cysts
What are the advantages to using zinc sulfate?
- commerically available
- floats protozoan cysts without distortion
What are the disadvantages to using zinc sulfate?
- may distort helminth ova
- some use magnesium sulfate
What are the advantages to using sodium nitrate?
- efficient at floating ova
- may even float fluke eggs
- commerically available
What are the disadvantages to using sodium nitrate?
- expensive to buy
- forms crystals and air bubbles
- distorts ova if it sits more than 20 minutes
- floats more fecal debris
What specific gravity should floatation solutions be between? Why?
- 1.200 - 1.300
- will make eggs float and debris/poop sink
How should your light be when examining unstained fecals?
Why hsould you drop your condenser down when examining fecals?
because it's a liquidq
What power(s) should you use?
Which technique works best for finding larvae?
What is the McMaster technique used for?
- for a quantitative fecal exam, mainly used for large animals to see if there are enough eggs to see if they are worth medicating
- weigh out feces
- add solution
- add to chamber
Who are at most risk for parasitic zoonoses?
What can you do besides using drugs to decrease transmission of parasites?
- get rid of feces
- prevent access to urine
- destroy ova/larvae
- human sanitation (wear gloves)
What are the different types of symbiosis?
_____ symbiotic relationships are parasitic.
Most symbiotic relationships are what?
What is an incidental parasite?
parasite in the wrong host (aberrant host)
What are the two types of vectors?
What is a fomite?
inanimate object transferring a parasite
What is the order of classification?
For a scientific name, what is capitalized and what is not capitalized?
- genus: capitalized
- species: not capitalized
What is a scientific name made up of?
genus and species
What is the silly memory trick for remembering the order of classification?
kings play chess or fight green snakes
What is another name for transplacental migration?
What is transplacental migration?
- larvae within the circulation leave blood and become dormant in muscles and organs until host becomes pregnant
- in late pregnancy larvae leave tissues, cross placenta and enter fetal tissues
- the neonate born with larvae
What is transmammary infection?
- arrested development until become pregnant
- larvae enter mammary glands of host
- larvae is then secreted in the milk
What are trematodes?
What are cestodes?
What are protozoa?
single celled organisms
What are nematodes?
What are acanthocephalans?
thorny - headed worms
Are acanthocephalans common in dogs and cats?
no, they are rare
What are arthropods?
- hard, segmented bodies
- insects and arachnids
What are the different types of hosts?
- transport (paratenic)
- aberrant (accidental)
What is a life cycle?
how parasite develops and reproduces
What are the different ways to diagnose parasites?
- observe adult parasite
- observe immature form (larva, egg)
- serological tests for antibodies
- clinical signs from patient
Why do we do fecal exams?
to diagnose the source of GI disease
What are some sources of GI disease that we can see in a fecal exam?
- hemorrhage in GI tract
- pancreatic insufficiency
What are the different types of fecal consistency we see in a gross exam?
Does the age of the poop affect the results of a fecal exam?
What types of parasites do we see in a gross exam?
What are proglottids?
tape worm segments
Does ova float in water?
What type of floatation solutions do we use?
- saturated sugar
- saturated salt
- sodium nitrate
- zinc sulfate
What are kits?
what you send home with clients to collect a fecal sample
What are different types of disposable kit?
Where does the centrifugal sedimentation concentrat ova?
at the bottom
When do we use centrifugal sedimentation?
use for heavy ova (flukes)
What part of the slide do we examine during a microscopic examination?
the entire slide
Will we ever need to go to high dry in microscopic examination?
What is a quantitative fecal exam?
find the number of eggs per gram feces
What types of serological tests do we use?
- western blot
What do serological test look for?
What do we need to do for client education?
explain treatments and why and when re-treatments may be needed and how the patient can be re-infected
What is treatment based on?
How do we prevent parasites?
- need to know life cycle (how it spreads, presistence in environment, reservoir hosts, intermediate hosts)
- drug therapies used for prevention
- sanitation techniques
How do we control the intermediate host?
- limit access to them
- avoid uncooked/undercooked meat
- remove other host (fleas, ticks, etc)
- monthly preventative drugs
When do we deworm cows?
early spring, 4 weeks, 8 weeks
When do we deworm horses?
When do we deworm pups/kittens?
every 2 weeks beginning at 2 weeks of age
What are the two ways the CDC say we need to do for treatment and prevention of parasites for dogs and cats?
- deworm at 2, 4, 6, 8 weeks of age and then every 3 months until 1 year of age
- deworm at 2, 4, 6, 8 weeks of age then begin monthly heartworm preventative year-round
What kind of periodic testing do we need to do for prevention?
fecal analysis & blood work