Ancylostoma caninum

Toxocara canis

Dirofilaria immitus

Capillaria aerophila

Oslerus (filaroides) osleri

Paragonimus kellicoti

small intestine

have tracheal migration

voracious blood suckers: cause anemia which can cause dyspnea

small intestines

have tracheal migration

Ollulanus

Toxocara cati

Dirofilaria immitis

Physaloptera

Platynosomum concinnum

Do both an antigen and antibody test;

echocardiography, radiographs looking for pulmonary arterial enlargement

sedimentation exam or a good Zn float, looking for thick shelled larvated eggs

Thelazia (the lazy eye?)

Draschia/Habronema

Onchocerca

Setaria

flies sponge up thin-shelled larvated eggs swimming around on the mucus of an infected horse’s eye,

they molt to L3 in the fly,

fly goes to another horse's eye and spits them out

Larvated eggs are passed in the feces and then taken in by flies, where they develop to L3.  The horse either accidentally eats the fly, or the larvae burst out of the proboscis of the fly if it is in the vicinity of mucus membranes, such as those in the mouth or eye.

Mosquitoes transmit L3, usually live in peritoneal cavity, but there can be some aberrant migration to the eye

A 6-month-old filly suffered repeated bouts of colic.  List 4 parasites that can cause colic in horses.

(Be sure to include a cestode.)

Cyathostomes

Strongylus vulgaris

Parascaris equorum

Anaplocephala perfoliata

 treat with Ivermectin, eradicate a closed herd by treating every 5 months for 2 years

A diagnostic lab reported microfilariae on the blood smear of a colt.  The veterinarians at the practice submitting the blood for routine testing disagreed on the significance of this finding. Defend or refute each response.

            Vet 1 – “Impossible!”

The peritoneal worm Setaria creates microfilariae that circulate in the blood.

Horses can also become infected with Onchocerca cervicalis, the nodular worm, which produces microfilariae that stay in the skin. They could possibly be picked up accidentally through puncturing the skin. (probably not though. know the microfilaria are in the skin not the blood.)

A diagnostic lab reported microfilariae on the blood smear of a colt.  The veterinarians at the practice submitting the blood for routine testing disagreed on the significance of this finding. Defend or refute each response.

Vet 2 – “Oh NO!  Heartworms!”

A diagnostic lab reported microfilariae on the blood smear of a colt.  The veterinarians at the practice submitting the blood for routine testing disagreed on the significance of this finding. Defend or refute each response.

Vet 3 – “Nothing to worry about.”    

If it is Setaria, then it is a harmless infection if it stays in the peritoneum, but it can have harmful effects if it migrates to the spinal cord

If it is Onchocerca then it can cause dermatitis, ocular problems, tendinitis (it's probably not onchocerca)

1.Toxoplasma gondii. It could also be Hammondia which is not pathogenic.  It is morphologically indistinguishable from Toxoplasma, so I would still give the same advice to the owner, just to be on the safe side.
Or it could be Besnoitia, but it is rare in domestic spp in the US 

Advice: give several treatments of Clindamycin to kill the tachyzoites, don’t let the cat dig around in the dirt or eat any wild animals, any pregnant, very young, or immunosuppressed individuals should take precautionary measures such as having someone else change the litter box every day, not gardening, washing fruit, cooking meat well.

The Benson family changes Fluffy’s kitty litter every 4 days. Every 4 days they throw Fluffy’s feces into the yard where their dog, Chipper, eats it. Explain why Chipper will/will not become infected with small oocysts approximately 10 – 12 um in size.

T.gondii – not in dogs as DH but can be IH; lots of damage from tachyzooites

Hammondiae – different species in dogs and cats

Besnoitia – not in dogs

if Toxoplasma: dog infected with Tachyzoites developing to bradyzoites since 4 days allows the oocysts to sporulate and become infective to an IH or DH. Tachyzoite replication can cause symptoms. You will not really notice any clinical signs in the dog—maybe myositis.

A local veterinarian leaves out food to attract raccoons to his yard.  Last night his bloodhound passed several large worms that looked a little like cestodes but had large spines on their heads.  He looked through his 15-year-old parasitology book and noticed they looked like parasites from pigs.  What are these worms, and how are they acquired?  What similar worms do pigs have and how do they acquire them?

These are Macracanthorhynchus ingens, and they are acquired by eating millipede intermediate hosts or rodent, snake, or frog paratenic hosts. 

Pigs have M. hirudinaceus and they acquire these by eating dung beetle or June bug intermediate hosts.

What 2 nematode eggs are occasionally found in dog urine? How are each acquired? What clinical signs are associated with each?

Dioctophyma—Ingestion of an aquatic annelid (IH) with the L3 stage or ingesting a Paratenic host (Fish, frogs, crayfish, etc). Clinical signs: kidney failure, enlarged kidney, peritonitis, abdominal pain, blood  in urine

Capillaria plica—ingestion of larvated egg or of a PH (earthworm). 

Clinical signs: none, cystitis, Hematuria, Dysuria, urinary incontinence.

Last year we diagnosed schistosomes in birds from an Oak Ridge Lake.  A few years ago, we necropsied a swan from the same area and found schistosomes.  Raccoons have recently populated that area also.  Explain any zoonotic concerns.

cercarial dermatitis or swimmer’s itch. 

The human schistosmiasis is a different species, and will not be acquired from birds, raccoons, or swans.

The first intermediate host is the snail with the miricidium and then the cercaria (infective stage) leaves the snail. The cercariae can penetrate skin of humans. There are three species:

                   Schistosoma—mammals including humans

                   Ornithobilharzia—birds

                   Heterobilharzia—dog, raccoon, bobcat, opossum

cystoisospora ohioensis or canis

strongyloides

Ancylostoma caninum

toxocara canis

How is the epidemiology of Eimeria in calves different from that of Cryptosporidium?

Eimeria is very species specific (E. bovis or E. zuerinii). 

PPP of 2-3 weeks, patent period of 1-4 weeks. 

live in the intestine, mostly large, but some small, and cause disease by cellular destruction. 

diarrhea with mucus and stringy masses of tissue, straining to defecate, anemia, anorexia, weight loss, retarded growth, and maybe even death. 

Cryptosporidium parvum infects all mammals and birds

PPP of 3-4 days

oocysts are passed sporulated in the feces and so are immediately infective. 

Lives in the small intestine. disrupts microvillous border of epithelial cells - prevent absorption

severe voluminous watery diarrhea, weight loss, dehydration, anorexia, abdominal pain, and may cause death.

A local goat owner is concerned.  His chickens have had severe problems with Eimeria.  Yesterday 2 kids (baby goats, not children) broke into the chicken pen and spent the day grazing in the oocyst-contaminated area.  Explain if the goats are/are not at risk for coccidiosis.

They are not because eimeria is very species specific. the species goats get are Eimeria ninakohlyakimovae or E. arloingi

1. The dog of the goat owner developed diarrhea after eating the droppings of eimeria infected chickens. Explain whether or not the Eimeria are causing the diarrhea. If not, what is?

No because eimeria is species specific and dogs don't have an eimeria species.

Chicken droppings can contain other pathogens like salmonella.

A swine farm is troubled with diarrhea in piglets.  What protozoal parasite is most likely involved?  How are the pigs infected?

Isospora suis.  The pigs become infected by ingesting oocysts containing sporozoites.

Cryptosporidium parvum or Eimeria (bovis or zuernii).  The calf would acquire them by ingesting sporulated oocysts (Cryptosproridium immediately infective when passed).  The owner should be very concerned that she could become infected with Cryptosporidium (it is really bad), but not Eimeria.

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

Fasciola hepatica—can also infect ruminants and other humans, and any mammal really
Haemonchus—can also infect goats

Tapeworms (taenia on the fecal float) are not affected by fenbendazole

treat with praziquantel and flea preventative

A calf with diarrhea was brought in for diagnosis and treatment.  A sugar flotation of the feces was negative.  No eggs, cysts, or oocysts were recovered.  Explain why you can or cannot be sure that coccidia are not responsible for the diarrhea.

You cannot be sure that coccidia are not responsible for the diarrhea, because the diarrhea may be caused before any oocysts are even produced.  They could be undergoing schizogony (asexual reproduction) and causing lots of problems before sexual reproduction and oocyst production begins.

Fascioloides magna was found in the liver of an elk that died in the National Park.  The elk originated in Canada where F. magna is common, but this was the first report of this parasite in TN. Explain any concern that cattle and sheep farmers might have about bringing this parasite into the east TN area.

If the cattle or sheep get F. magna, they will never pass eggs into the environment because the cysts will never make the communication with the bile duct, but they will cause problems in that animal.  In cattle, some sickness may occur while they’re migrating in the liver.  In sheep, they migrate and never settle down, so they cause problems until the sheep die.

Proglottids are recovered from the feces of a 5-year-old, indoor/outdoor cat.  What are the pros and cons for treating the cat?  Why should you attempt/not attempt to determine which species of tapeworm is infecting the cat?  Discuss if a fecal flotation should be run on the cat even though proglottids have been seen.

Tapeworms don’t usually cause much problem in cats other than perianal irritation, but they do cause distress to the owner.  Also, if the tapeworms are Dipylidium caninum, they are zoonotic.  That is also the only reason you would bother determining the species, since Praziquantel can kill any of the tapeworm species.  Run a fecal float to determine the species.

A company representative recently commented that perhaps in a year or so after Revolution (selamectin) is widely used, we will no longer need to teach about tapeworms.  Explain his logic.  Explain why you agree or disagree.

Revolution kills fleas which carry Dipylidium caninum.

could still have contact with a flea (it only takes one) due to neighbor’s dog not having flea control, or coming in contact with an infected yard or house, or contact with wild animals that carry fleas.

Revolution does not have any way of preventing tapeworm infection if the animal eats a flea.

fleas are not involved in the spread of the other tapeworms, Taenia spp.

A 4-H agent noticed small worms in the manure of several calves that the students were raising.  Because the calves are young (about 2 months), he treated them with Ivomec, but has continued to see the tiny white segments after treatment.  What worm is he probably observing?  Why is the Ivomec not effective?  What anthelmintic will you recommend?

He is probably observing Moniezia, which is not susceptible to Ivomec (ivermectin). 

Fenbendazole, Ofendazole, or Albendazole.

List all animals that pass Toxoplasma gondii oocysts in the feces.  Why is the prevalence of toxoplasmosis in veterinarians not higher than in the general public?

Only cats (definitive host) pass T. gondi oocyst in the feces.

Parasite takes 1-4 days in environment to sporulate and be infective.

Most veterinary clinics will be changing litter every day (at least) preventing sporluation

Since clinicians use good hygiene practices and are aware of the parasite, their prevalence of getting toxoplasmosis is the same or even less.

Can also get from eating undercooked meat, congenitally, and orally where oocysts are out in the environment.

The client should be informed of the species and how to prevent it.  Taenia species: DH consume metacestodes in rabbits, rodents, ruminants, deer, and similar IH. 

If Taenia: prevent predation to avoid reinfection and allegations of drug resistance (or retreatment to make extra money) from the client. 

if Dipylidium caninum: flea control 

praziquantel to prevent reinfection through the ingestion of fleas infected with metacestodes.

owner should be educated on zoonosis from ingesting fleas (esp if children in house).

Lydia works on the Ag campus here at UT. One of her colleagues adopted a dog that was previously a stray that roamed our campus. On a routine examination we diagnosed Paragonimus in this dog. Lydia frequently walks the trails in this area with her cat, Ferguson, who loves to eat the snails in the creek. She is concerned that Ferguson will also develop lungworm infection from these snails. Please outline the discussion you will have with Lydia on the possibility of her cat becoming infected with this parasite.

Dogs cannot get lungworms from ingesting the snails.

1^st IH: snail infected with meracidium. 

meracidium undergoes asexual reproduction to form the cercaria that leaves the snail and enters a crayfish, crab, or other freshwater crustacean (2nd IH). 

The cercaria matures into metacercaria in 2^nd IH 

ingested by the cat or dog, DH. 

prevent predation of snails for other reasons 

aelurostrongylus, another lungworm, could rarely be caught by eating a snail with L3 though it's normally through a paratenic host

also prevent crustacean predation.

Perry’s boxer, Jo Jo, is passing white segments in the feces which you examine and diagnose
as Taenia proglottids. Perry is now worried that his inside cat Punkie is also infected with these
tapeworms because Punkie has ingested some of the tapeworm segments from Jo Jo’s feces.
Explain why Punkie will/will not become infected with tapeworms from eating the segments.

Taenia is obtained from eating ruminants and rabbits infected with Taenia metacestodes.

  The metacestodes become mature worms in the small intestine that pass the proglottids in the feces. 

In order to complete the cycle the proglottids must be consumed by the IH, mature into metacestodes, and THEN be eaten by JoJo.

Also, cats don't get the dog taenia - their species is separate.

Discuss what makes an animal a suitable definitive host. To answer this you may want to list 3 objectives the parasite must be able to achieve in the host. Remember – what is the parasite's goal in life?

1.    Must harbor the adult stages so that sexual reproduction can occur

2.    The results of sexual reproduction, oocyst, sporocysts etc., must be able to leave host and cause infection in another organism (to perpetuate the cycle)

3.    Host would preferably not be killed by parasite or kill parasite

Pick the correct answer and explain your response:  Cats that are actively excreting Toxoplasma gondii oocysts in their feces usually...

a.    are asymptomatic

b. develop hemorrhagic diarrhea concurrent with severe dehydration.

c. fail to groom themselves properly and as a result, are likely to become reinfected.

d. suffer from tenesmus and hematochezia.

Answer

a.    are asymptomatic – if the cat is the definitive host T. gondii replicates in the GI and pass oocysts; however, if the cat also acting as an IH tachyzoites can enter the tissues and cause damage due to their rapid multiplication and cell destruction

1.      Pick the correct answer and explain your response: Control of Potomac horse fever in unvaccinated horses includes:

a.       Administering prophylactic doses of praziquantel to control the vector flukes

b.      Routine application of insecticides to horses to prevent feeding by flies

c.       Administering prophylactic doses of penicillin antibiotics to control the Neorickettsia (Ehrlichia) risticii

d.      Avoiding aquatic habitats that may be more likely to harbor infected trematodes

e.       Protecting feed and water from possible contamination with opossum feces

answer : 

d.      Avoiding aquatic habitats that may be more likely to harbor infected trematodes

explain:

Life cycle:  Neorickettsia risticci parasitizes trematodes, trematodes pass eggs, infects snail, flies infected, horses drink flies

If aquatic habitats that harbor these trematodes are avoided then the flies in the area will not be infected with the bacteria, and the horses will not obtain the disease by accidental ingestion of the flies.

1.      Pick the correct answer and explain your response: The pregnant, cat-owning client most at risk for passing toxoplasmosis to her fetus during gestation is one who:

a.       Does a lot of backyard gardening

b.      Does not have a high circulating Toxoplasma antibody titer at the time of conception

c.       Has a high circulating Toxoplasma antibody titer at the time of conception

d.      Has repeatedly eaten raw or rare meat

e.       Owns a cat with a high circulating Toxoplasma antibody titer at the time of conception

answer:

b.      Does not have a high circulating Toxoplasma antibody titer at the time of conception

Explain:

                                  If a woman has never been exposed to Toxoplasma before, if she has her first exposure while pregnant, there could be severe results for her baby. Risk is for a non-immune mother to be exposed DURING pregnancy. It is important to be exposed BEFORE pregnancy…or after…but not during.

Pick the correct answer and explain your response:
In recent years, several commercially-available equine dewormers have been modified to
include praziquantel. What was responsible for this change?
a. new data describing trematodes as a parasite of horses
b. new data describing tapeworms as a parasite of horses
c. new data demonstrating the clinical association between cestodes and colic
d. new data demonstrating widespread anthelmintic resistance in equine nematodes to the
macrocyclic lactones

answer: c. new data demonstrating the clinical association between cestodes and colic

the cestode Anaplacephala perfoliata has been shown to cause colic in horses, while the other cestodes are basically harmless.

this is because A. perfoliata likes to set up at the ileocecal valve, causing inflammation and possibly digestive blockage.

praziquantel is effective against cestodes (tapeworms) so it will prevent this type of colic.