-
Define trophozoite.
motile form
-
Define bradyzoite.
resting form in tissue cysts
-
Define cysts.
resting form, may be passed in feces
-
Define oocyst.
passed in feces
-
Define tachyzoite.
destructive form
-
Who does Giardia affect?
anything that is mammal
-
What species can serve as reservoirs in nature for Giardia?
beavers
-
Is there an intermediate host for Giardia?
no
-
Where does Giardia infect its host?
small intestines
-
What clinical signs are there with Giardia infection?
- diarrhea
- cramping
- anorexia
- flatulence
- weight loss
-
What is the infective form of Giardia?
trophozoite
-
How does Giardia enter the body?
through food or water
-
What is the prepatent period of Giardia?
1 - 2 weeks
-
How is Giardia diagnosed?
- trophozoites are found in fresh direct fecal smears
- IFA
- EISA
- Small cysts can be found on centrifugal floataion with zinc sulfate as the flotation medium
-
What is the treatment for Giardia?
- Metronidazole
- Dogs and ruminants: fenbendazole
- Albendazole for large animals
-
How much metronidazole would a 44 pound dog need if you are asked to dose it at 50 mg/kg QD x 5d to treat Giardia?
20, 000 mg
-
Are pet owners more commonly infected with Giardia than people who have no pets?
no epidemiologic relationship between pet owners and human infection
-
Is there a vaccine for Giardia?
yes
-
What flagellate causes venereal disease, abortion, and infertility in cattle?
Tritrichomonas fetus
-
How is tritrichomonas fetus diagnosed?
- see organisms on cytology from vagina/prepuce
- serology of bulls
- culture of preputial flush
-
What organism causes canker in birds?
avian trichomonas
-
How is avian trichomonas diagnosed?
- crop wash
- DQ stained smear of lesion
-
What is the reservoir of Balantidium coli?
swine
-
Association with what species increases the risk of Balantidium infection in humans?
swine
-
Which protozoan we discussed has the largest cyst form?
Balantidium
-
What is commensal?
living with, on, or in another, without injury to either
-
Are most species of amoeba harmful?
no, most are non-pathogenic
-
What type of test will give you the best chance of finding intestinal protozoan trophozoites?
fresh direct fecal smears
-
What type of test will give you the best chance of finding Giardia cysts?
centrifugal flotation
-
What is the definitive host of Toxoplasma gondii? Where does it live in the definitive host?
-
What is the intermediate host of Toxoplasma gondii? How is the intermediate host affected?
- amphibians, fish, reptiles, birds, and all species of mammals
- lymph nodes, heart, skeletal muscle, brain
-
How can the intermediate host become infected with Toxoplasma gondii?
- ingestion of bradyzoites in meat
- ingestion of oocyts
-
How is the definitive host infected with Toxoplasma gondii?
cats ingests tissue cysts containing bradyzoites (usually by eating mice)
-
What are the three life forms of Toxoplasma gondii?
- oocysts
- tachyzoites
- tissue cyst containing bradyzoites
-
How big are toxoplasma oocysts?
10 - 12 microns (small)
-
What happens after a cat eats an infected mouse? Describe the life-form changes.
- cat ingests bradyzoites from mice
- bradyzoites "hatch"(turn into tachyzoites) and penetrate the epithelial cells of the small intestines
- reproduction occurs
- cat sheds unsporulated oocysts
-
Are Toxoplasma oocysts infective immediately upon being released into the environment?
no...it takes 1 - 3 days in the environment for the oocysts to become infective
-
Is Toxoplasma considered a dange in immunocompetent individuals? What happens to the organism in an immunocompetent intermediate host?
- no
- there are no clinical signs
-
What three organ systems are most commonly affected in the cat?
-
Are cats showing signs of disease caused by toxoplasmosis usually shedding oocysts?
no
-
Is there a Toxoplasma antigen test?
no
-
How long will a positive antibody titer (concentration) for Toxoplasma last in the cat? What precent of healthy cats are seropositive?
- positive titers last for years
- this does not mean the cat is shedding oocysts (not shedding = no danger to humans)
- 40%
-
Does a positive test mean a cat is infected with Toxoplasma?
no, it just means at some point in its life it ingested the infection
-
Can a healthy cat test positive for Toxoplasma?
yes
-
List all the preventative measures pregnant women should take to avoid contracting toxoplasmosis.
- avoid litter boxes
- if they can't avoid litter boxes: wear gloves while scooping litter, clean litter box daily before oocysts can sporulate and become infective
- meat should be cooked well
- wash hands after handling raw meat
- wash fruits and vegetables well
- wear gloves while gardening
- cover outdoor sand boxes
-
What organism that causes abortion in ruminants was until recently believed to be Toxoplasma?
Neospora caninum
-
What are the three forms of Neospora caninum?
- tachyzoites
- bradyzoites
- oocysts
-
Who is the definitive host for Neospora caninum?
dogs
-
Can Neospora caninum be spread vertically (from mother to baby)?
yes...can cross placenta and infect fetus
-
What is the intermediate host of Isospora? Eimeria?
there is no intermediate host
-
In general, are protozoan oocysts resistant in the environment? Are they infective immediately upon entering the environment?
no and no
-
What is the genus name of the parasite you have probably seen in fecals from puppies or kittens? Is it zoonotic?
-
Why do you sometimes see blood in feces from puppies or kittens infected with isospora?
because they reproduce in intestinal cells which causes diarrhea, blood, and or mucus
-
Is the life cycle of Isospora direct or indirect?
direct
-
What is the prepatent period of Isospora felis or canis?
1 week
-
Why would a veterinarian choose not to treat Isospora infection in a healthy, asymptomatic animal?
because this type of animal typically has an immune system strong enough to take care of it itself...they develop an immunity over time
-
How is it that Cryptosporidium can enter municipal water supplies?
because occysts are found in about 65-97% of surface water (lakes, ponds, swimming pools, etc)
-
How is Cryptosporidium diagnosed?
- small oocysts found on fecal float
- acid-fast staining
- immunofluroescent staining
- ELISA test for antigen
-
What does Crytosporidium cause?
-
Is there an intermediate host for Cryptosporidium?
no
-
Is Cryptosporidium zoonotic?
yes
-
What species commonly carry Cryptosporidium?
- calves under 4 weeks of age
- small ruminants
-
Describe what happens in "autoinfection" and why parasites that can undergo this phenomenon can be so dangerous.
- autoinfection is the ability of a parasite to re-infect a host without ever passing out of the host.
- this is dangerous because it can cause an overwhelming infection
-
Of the ones we've discussed, which parasitic protozoan oocysts are the smallest?
cryptosporidium
-
Is there an epidemiological relationship between being in the veterinary profession and contracting Cryptosporidium?
yes...rates of infection are higher in the veterinary profession
-
What is the causative organism of EPM?
sarcocystis neurona
-
What is the definitive host of sarcocystis?
opossums
-
What kind of host is the horse for EPM?
aberrant
-
What species serve as intermediate host for EPM?
-
How do horses become infected with EPM?
the sporocysts are ingested in opossum feces. they get into the GI tract and then the blood and then the CNS
-
What species spreads EPM through its feces?
opossum
-
How is it best to diagnose EPM in horses?
antibodies in CSF (blood tests only indicate exposure)
-
What kind of pollen has the "Mickey Mouse ears"?
pine pollen
-
What types of protozoa will we be studying?
- flagellates
- amoebae
- ciliates
- coccidians
-
What are the different types of flagellates?
- giardia
- tritrichomonas
- trichomonas
-
What does the trophozoite of giardia look like?
- tear drop
- two nuclei "eyes"
- 8 flagella (4 pairs)
-
What type of reproduction does giardia have?
asexual
-
Describe cyst ingestion of giardia.
- trophozoites divide by longitudinal fission (asexual reproduction)
- they proliferate in the small intestines
- trophozoites are then passed in diarrhea but are incapable of causing infection and soon die
-
Where do cysts for giardia attach in the small intestines? What does it do there?
- brush border of small intestines
- absorb food
-
What do the "suckers" of the giardia cysts do to the small intestines and what does this cause?
- damage villi where they attach
- causes secretory diarrhea
-
Which is the most common intestinal parasite in people in North America?
giardia
-
What species does Balantidium coli infect?
- dogs
- primates including humans
-
What kind of life cycle do Balantidium coli have?
direct lifecycle
-
Where do Balantidium coli infect?
the large intestines
-
What are the symptoms of Balantidium?
- often asymptomatic
- can cause diarrhea, abdominal pain, can be severe in debilitated humans
-
How do animals get entamoeba histolytica?
humans spread to pets
-
What are the symptoms of entamoeba histolytica
- diarrhea
- ulcerative colitis
-
What are the different coccidians?
- isospora and wimeria
- cryptosporidium
- toxoplasma
- sarcocystis
- neospora
-
How are coccidians spread?
by ingestion
-
How do you diagnose coccidians?
- on float or direct smear
- may be hard to find so seological tests exists
-
Define sporocyst.
passed in feces
-
Define sporozoites.
invade cells
-
Define merozoite.
dividing form
-
Define meront.
in tissue cysts
-
Define microgamont.
sperm
-
-
What are the different life forms of toxoplasma in cats and what do they do?
- oocyst (shed in feces)
- tachyzoites (detrimental, motile form)
- bradyzoites (resting form in tissue cysts)
-
Which organ system in cats becomes infected with toxoplasma?
any of them
-
Are seropositive cats a risk to humans?
no
-
Describe the life cycle in the intermediate host for toxoplasma.
tachyzoites form and invade and multiply in any tissue. they for tissue cysts containing bradyzoites in muscle, organs and CNS
-
What can toxoplasma cause in human babies?
- abortion
- blindness
- retardation
- seizures
-
If a pregnant woman has a positive titer test for toxoplasma, what does that mean?
she is protected
-
What are the clinical signs of Neospora caninum?
- neurological (ataxia, stiffness, circling, ascending paralysis, and rigid hyperextension of hind limbs)
- muscle atrophy
- seizures
- head tilt
-
Who is most commonly infected with Neospora caninum?
puppies 5 - 6 weeks old
-
What is the treatment for Neospora?
-
How is Neospora diagnosed?
- histology
- serology in large animals
- PCR
-
How do you prevent Neospora?
avoid feeding dogs raw meat diets
-
What are the different intestinal coccidia?
- isospora
- eimeria
- cryptosportidium
- sarcocystis
- toxoplasma
-
What kind of life cycle does isospora and eimeria have?
direct life cycle (no intermediate host)
-
When do isospora sporulate?
1 - 2 days (eimeria takes longer)
-
How do animals get isospora or eimeria?
- host eats infective oocyst
- sporozoites hatch and enter intestinal cells
-
What animals get eimeria?
- cattle
- sheep
- goats
- swine
- rabbits
- poultry
- horses
- not found in dogs or cats
-
What is the treatment for isospora and who do we treat?
- sulfonamides and environmental control (strong ammonium hydroxide...resistant to most disinfectants)
- neonates
-
Where do cryptosporidium live in hosts?
intestines
-
What is the treatment for cryptosporidium?
supportive care
-
Cryptosporidium can be fatal for what kind of people?
immunocompromised people
-
How do people typically get cryptosporidium?
public water sources
-
What kind of life cycle does sarcocystis have?
predator-prey life cycle
-
Define the predator-prey life cycle.
- sporocysts passed from definitive host
- sarcocysts live in muscles of intermediate host (prey species)
- birds/insects transport hosts
-
What does sarcocystis cause in rottweilers?
- encephalitis
- dermatitis
- myocarditis
-
What are the clinical signs of EPM?
- ataxia, incoordination
- muscle atrophy
- facial paresis/paralysis
- difficulty swallowing
- collapse
- seizures
-
What does EPM stand for?
equine protozoal myeloencephalitis
-
What is the treatment for EPM?
Marquis antiprotozoal paste
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