Why are the haemosporidia usually more pathogenic than the intestinal coccidia?

  Abortions plagued a local dairy goatherd last winter and this spring.  What protozoan will be first on your differential list?  What other protozoal parasites will you include on the list?  How are each of these 2 protozoans acquired? 

Sarcocystis capracanis- A goat is the intermediate host and infected by ingestion of the sporulated oocysts containing 2 sporocysts with 4 sporozoites. These sporozoites invade the vascular endothelial cells.

Toxoplasma gondii- Goats (Intermediate Host) are infected by ingestion of the sporulated oocysts and will form tachyzoites and bradyzoites. A kid could be infected transplacentally due to focal placentitis which would cause the doe to abort.

Neospora caninum- A goat could be the intermediate host and infected by ingestion of the sporulated oocysts or a kid could be congenitally infected from transplacental infection.

 Tritrichomonas foetus- (Bovine trichomoniasis) As a veneral disease, it is acquired through sexual transmission. This pathogen is inapparent in bulls; however, the infected bull is usually the cause of spread. The trophozoites are transferred during copulation.

Sarcocystis cruzi- A cow is the intermediate host and infected by ingestion of the sporulated oocysts containing 2 sporocysts with 4 sporozoites. These sporozoites invade the vascular endothelial cells and can cause abortions in cows (and pigs).

Neospora caninum- A calf can be infect transplacentally and an adult can be infected by ingesting sporulated oocsyts.

Which of the parasites on the “goat-abortion” list would be unlikely on the “cow-abortion” list?

Toxoplasma gondii. “Adult cattle appear to be resistant to toxoplasmosis, whereas sheep and goats are susceptible, usually manifesting toxoplasmosis as abortion due to focal placentitis”

Why are fecal exams of dogs not always predictive of Giardia infection?  How can the predictive value of these exams be improved?  That is what tests should be performed and how frequently?  List some alternatives.

The giardia cysts are passed intermittently, not continuously. Trophozoites, although not usually passed in the feces, may be detected on direct fecal smears. Cysts may be concentrated by fecal flotation in zinc sulfate, ran 3 times over a 5-7 day period. A phase contrast microscope or a drop of Lugol’s solution (which will stain the cysts) are helpful tools when trying to analyze a fecal float or direct smear.  Most recently, antigen detection kits have become available which accurately detect infection of Giardia.

What parasites would you suspect in a 5-week-old puppy with diarrhea?  Two protozoans should immediately come to mind.  List three helminth parasites also (2 common, one less common).

What additional parasite would you list if the dog were 5-months-old instead of 5-weeks old?

protozoans: cryptosporidium canis, cystoisospora canis or ohioensis

helminths: toxocara canis, ancylostoma caninum, less common strongyloides

additional for 5 months: trichuris vulpis

Test: Sugar fecal float with centrifuge for long time, IFA, acid fast stain/ other special stains, PCR, ELISA

Prevention: Good sanitation, isolate sick

Test: Sugar Float

Prevention: Prevent predation, clean up environment (don’t allow eggs in feces to sporulate)

Test: Clinical signs, fecal float

Prevention: monthly prophylaxis, prevent predation

Test: sugar fecal float

              Prevention: pick up feces (avoid infective larvae), prevent predation

Test: fecal float, Baerman or zinc sulfate for larvae

            Prevention: raise in uncontaminated environment, avoid moist, muddy areas

Test: sugar fecal float

        Prevention: pick up feces as soon as possible, can live in environment for many years, monthly     prophylaxis

A swine farm is troubled with abortion in sows and diarrhea in the piglets that are born and survive.  List two protozoa that could be involved in the abortions.  What protozoon is most likely involved in the diarrhea in the piglets? 

Cystoisopsora suis (one most likely involved in diarrhea in piglets)

                Sarcocystis (abortion and diarrhea in IH)     

A 3-month-old calf has diarrhea.  What protozoan parasites will be included on your differential?  Include at least 4 different genera. List these genera by prevalence- that is- from most common to least common.   

Treatment: treat coccidiosis with Sulfadimethoxine, Amprolium, supportive care

Prevention: coccidiostats (amprolium, decoquinate, lasalocid, monensin), avoid stress and overcrowding, good sanitation, avoid wet, contaminated areas, provide facilities with minimum fecal contamination of feed and water

Treatment: no approved treatment, maybe paromomycin, tylosin axithromycin, or nitazoxanide. Supportive care until develop immunity is important

Prevention: good sanitation and isolate sick

Treatment: sulfadizamine

Prevention:keep dogs/cats out of herds for a couple of weeks so they stop passing cysts

Treatment: no drugs in US with label claim for giardia, albendazole best for cattle, or febantel

Prevention: Treat all animals, clean up feces daily with gloved hands, disinfect contaminated areas (scrub boots), eliminate standing water and moist areas in stables and pastures.

What protozoal parasites can be diagnosed on a blood smear (stained) exam of a dog?  List at least four different genera.

• Babesia sp.
•  Leishmania
• Hepatozoon
• Trypansoma cruzi

On a routine fecal exam of a horse, many trichomonads are seen on a direct smear.  Explain what should be done now.

        Explain how your response would be different if these were on the fecal exam of a Pixie-bob cat.

Tritrichomonas spp are not pathogenic to horses, so nothing needs to be done unless affected species are in contact.

Pathogenic to cattle, cats, and humans (abortion in cattle and cats, vaginitis in humans)

Tritrichomonas foetus causes feline trichomonal diarrhea (‘cow patty’ feces, dribbling feces) and abortions in cats.

If you found 10 –12 um oocysts in the feces of a dog, what organism/s would be producing them?  Explain any zoonotic/heterospecific concerns.

·         Neospora

·         Not zoonotic

·         Dogs: neurologic signs, hind-limb paresis

·         Cattle: abortion

·         Hammondia

·         Not zoonotic

·         Dogs: not pathogenic

·         Cats: not pathogenic

·         Giardia

o    Zoonotic

o    Mammals: profuse diarrhea

Cryptosporidium and Giardia are frequently considered "water-borne" parasites.  Explain whether or not transmission occurs in the United States where all municipal water is treated with chlorine.

Transmission is still possible in chlorine treated water. Chlorine has no effect on Cryptosporidium or Giardia. However, municipal water is also under constant filtration. Additional treatments, such as ozonization, of the water, helps eliminated the transmission of both organisms. Transmission of these organisms could occur in cities that do not implement this additional treatment process since chlorine treatment alone will not eliminate these two organisms. 

What protozoal parasite should be considered in a horse with neurologic signs?  How would you test for it?  How do horses acquire the infection?  What causes the neurologic problems?  How can this be prevented and treated.  Why do we say the horse is not an Intermediate host?

Sarcocystis neurona

Test: serological antibody or CSF Western Blot

A fecal float would not be successful because the horse will not be passing oocysts or bradyzoites.  The horse can become infected from ingestion of the sporulated oocysts from the environment that are passed from the definitive host, the opossum. The horse is a dead end host, not an intermediate host, because there is no development or reproduction.

Neurological problems arise in the horse from tachyzoites which damage the CNS.

Prevention methods: avoid wild life such as opossums, store food properly, remove any dead carcasses from the environment, vaccination.

Treatment measures should include inflammation reducing medication, elimination of tachyzoites, and the use of Ponazuril or the combination drug, Sulfadiazine and Pyrimethamine.

What parasites can cause anemia in dogs?  Cats? (Include protozoa, arthropods, and helminths)

Dogs:

protozoa: babesia, sarcocystis, Plasmodium, Hepatozoon, Trypanosoma, Leishmania, Isospora

arthropods: Ctenophalides felis or canis, Rhipicephalus, Amblyomma

helminths: A. caninum, Trichuris vulpis, T. canis

Cats:

protozoa: Babesia, Sarcocystis, Plasmodium, Hepatozoon, Trypanosoma, Cytauxzoon, Leishmania, Isospora

arthropods: Ctenophalides felis or canis, Rhipicephalus, Amblyomma

helminths: A. tubaeforme, T. cati

What two helminth parasites are most likely to be responsible for anemia and bottle jaw in sheep?  What other animals can these parasites infect?  (Remember to include a Trematode)  What protozoan can also cause anemia in cattle?

Haemonchus: can infect cattle, goats

Ostertagia: can infect cattle, goats

Fascioloa hepatica – the common (sheep) liver fluke

•   can also infect → other mammals, including cattle and people!

Sarcocystis - cattle are the intermediate host, along with other herbivores, omnivores, and birds; carnivores, people and birds are the definitive hosts, which usually don't present any clinical signs

How is the epidemiology of Babesia gibsoni different from B. canis?  What signalment, clinical signs, and history would prompt you to consider B. gibsoni rather than B. canis?

babesia gibsoni: Rhipicephalus sanguineus tick or blood-blood contact. most common in fighting pit bulls

babesia canis: Rhipicephalus sanguineus OR Dermacentor variabilis, blood transfusions, transplacental. most common in greyhounds.

signalment: susceptible breeds as above.  history: fighting, outdoor dog, blood transfusion. Babesia gibsoni is more pathogenic than B. canis. clinical signs are fever, anorexia, wt loss, icterus, hemoglobinurea, inc pulse, resp rate,splenic and hepatic enlargement, possible death.

A dog from Soddy Daisy was diagnosed by spleen biopsy to have Leishmania.  Prior to living in TN, the dog was a military dog stationed in Spain.  How was the dog probably infected?  What dog breed is most likely to have Leishmania spp in this country?  How is Leishmania infantum spread from dog to dog in N.A.?

What 3 protozoal parasites would you include on the differential list of a dog with partial paralysis and myositis?  How are dogs infected? 

•   Neospora – dogs acquire Neospora through the ingestion of bradyzoites in the tissues of the intermediate hosts (cattle, sheep, goats, cats, and other dogs)

•   Hepatozoon- dogs are infected through the ingestion of an infected tick vector (Rhipicephalis or Amblyomma) containing the sporozoites

•   Trypsanoma cruzi- dogs are infected through the ingestion of infected kissing bugs, blood transfusions from infected animals

•  ***Toxoplasma gondii- dogs (intermediate host) become infected through the ingestion another intermediate host with bradyzoites in tissues; can also become infected through the ingestion of sporulated oocysts. ***doesn't cause paralysis, just causes neuromuscular problems!****

Why is Cytauxzoon more common in outdoor cats than indoor cats?  What animals are reservoir hosts for this parasite?

Cytauxzoon is more common in outdoor cats than indoor cats because the protozoa is transmitted via tick bites by Dermacentor variabilis (American dog tick) or Amblyomma americanum (Lone Star tick).  The tick ingests the parasite from infected RBCs of an infected feline.  Within the tick, gametogony and sporogony occurs.  The sporozoites are injected into a feline when the tick bites, schizonts infect WBCs, and travel to the liver, lung, spleen, and bone marrow.  Merozoites then infect RBCs and the cycle occurs again. 

- Reservoir hosts are bobcats (Lynx rufus).

Why is Trypanosoma cruzi common in wildlife in the United States, but rare in people and in low prevalence in dogs in the US as compared to dogs in other countries? Why is the prevalence in dogs increasing in the US?

Infection occurs via bite by an infected bug, ingestion of the bug, penetration of infected bug feces into wounds, or transplacentally.

Trypanosoma cruzi is common in wildlife in the US because the IH is the Reduviidae (kissing bug) which normally lives in old buildings and nooks and crannies out in the wild, so wildlife are more likely to encounter the bug than are humans and domesticated dogs.

In the US, houses are more secure and people will usually treat homes for insect pests thereby diminishing the risk of exposure, though it does happen.  In other countries where the disease is prevalent (South, Central, and some parts of North America), prevalence in dogs is greater in other countries due to poorer housing and vector control. 

The prevalence in dogs is increasing in the US because there are wildlife vectors in the US, and spread into non-endemic areas is increasing due to immigration over country borders.

  Blood-transfusions can be a source of transmission, so the introduction of infected dogs and humans serve as sources of new infection.

  Fecal exam confirmed that our administrative professional’s 6 week old puppy, Junior, was passing Ancylostoma caninum eggs.  What did we advise her to do?

At 3 months, we again checked Junior’s feces and found Giardia cysts but no hookworms.Tressie (our administrative professional) reported that her friend’s two month-old dog, Geno (the friend is a U Conn fan), visited last night and ate Junior’s fresh feces. (The dog ate the feces; the friend did not.)  Explain whether or not Geno will become infected with Giardia because he ate these feces.

Tressie constantly holds Junior and kisses him in the mouth and other parts of his body.   Explain her chances of acquiring Giardia.

List parasites that may be involved in respiratory problems in cats (five nematodes, one trematode, two protozoa, one arthropod)

nematodes: A. tubaeforme, T. felis, Aelurostrongylus,  Dirofilaria immitis, Eucoleus/capillaria aerophilus

trematode: paragonimus

protozoa: toxoplasma gondii (intermediate host)
arthropod: various ticks cause tick paralysis

acquired from ingestion of paratenic host infected with L3 (amphibians, reptiles, birds, rodents) or ingestion of intermediate host with L3 (snails and slugs)

ingestion of larvated egg or ingestion of paratenic/intermediate host (earthworms)

mosquitos (IH) will ingest blood from a cat with microfilaria.  The microfilaria will molt to an L3 stage in the mosquito.  When the mosquito bites a cat, the infective L3 stage is deposited into the skin.

ingest second intermediate host (crayfish and crabs- crustaceans) infected with metacercaria. (The crustacean infected from cercaria from first IH- snail).

Although many cats infected with Toxoplasma gondii do not exhibit clinical signs that we notice, on occasion infected cats do have respiratory distress and other problems.  What actually causes these clinical signs? 

A former racing greyhound from Florida was shipped to TN for adoption.  Two years later a mixed-breed dog that also resided in the house, developed fever and severe anemia.  A haemosporidian was found in the erthrocytes on a blood smear of this mixed-breed dog..  The greyhound was also serologically positive for this parasite.  The dogs had never fought, and there had been no exchange of blood.  The dogs stayed in the apartment except when they were walked in downtown  Knoxville. Offer a plausible explanation for how this organism was evidently transmitted from one dog to the other.  What is the organism?  What other parasite is also present?

The dogs are infected with Babesia canis.  Both dogs were infected through a tick bite by Rhipicephalus sanguineus (brown dog tick) or perhaps Dermacentor variabilis (American dog tick) that was infected with sporozoites.  The sporozoites were passed in the tick bite.

In July, you are called to a poorly managed dairy farm.  Six of nine, 3-month-old calves - kept in an old barn where dogs, cats, and pigeons are also living - are acutely ill with anorexia, severe weight loss, lameness, and hair loss from the extremities.  What protozoan parasite do you suspect?  Explain how the environmental conditions are related to the spread of the disease.  How could this disease have been prevented?  What treatment is appropriate?

Sarcocystis spp. is likely the cause because cows are the intermediate hosts. Because the cows are in a barn where dogs, cats, and pigeons are also living, it is likely that sporocysts in the environment.  This is because carnivores, people, and birds are the definitive hosts and will pass spococysts in their feces.  If the cows ingest the sporocysts, they will develop clinical signs from the tachyzoites undergoing schizogony. This could be prevented by preventing dogs and cats from defecating in the pastures or barn (or simply separating them altogether). Sulfadiazine and pyrimethane are used to treat Sarcocystis in cattle.

Circle the correct answer and explain why this is true: What is the most probable explanation for cysts in the feces of a dog that was treated for Giardia with fenbendazole 2 weeks ago.

A.Giardia is resistant to fenbendazole

      B.  Misdiagnosis

      C.  Reinfection

      D.  Selection Pressure

      E.  All of the above

C. reinfection

Giardia cysts are very hardy in the envirionment and immediately infective. Reinfection can easily occur if proper preventatives measures are not taken. If the original source of infection was cleaned, then the dog can be contaminated from there. Also, if the dog is not bathed well during its infection it can reinfect itself while self grooming. This is why frequent bathing during a Giardia infection is recommended. 

PPP 5-14 days

rhipicephalus sanguineus (brown dog tick)

Rhipicephalus annulatus

Sandfly (Phlebotomine; Luxomyia)

Triatoma spp (kissing bug)

mosquito (eg Aedes albopictus)

Borrelia burgdorferi (Lyme disease) vector