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249 Cards in this Set
- Front
- Back
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true or false: worms are usually highly host specific and can only live in its specific host?
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False
Worms are highly adapted to the DEFINITIVE host, but in many cases can also have an intermediate host. |
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true or false: worms do not undergo asexual multiplication in the definitve host?
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false.
Most worms multiply sexually. Some are parthenogenic. |
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what age group is most at risk for worm infection?
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young
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why, in many cases, do we accept worm control versus complete eradication?
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because they are very hard to eradicate completely and small numbers are usually not very pathogenic.
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true or false: an individual animal's susceptibility to a high worm burden is highly dependent on external conditions such as nutrition and exposure to other infections agents?
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False. An individual's susceptibility to a large worm burden is by-and-large a heritable trait.
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what type of immune response is typical of a worm infection?
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Th-2, eosinophilic (recall: IgE)
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compare the treatment objectives for helminth infection in small animals versus food animals versus horses.
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Small animal:
- Elimination - Best products from vet - Cost less important Food animals: - Control - Product usually not from veterinarian - Cost very important Horses: - Aspects of both |
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which organization(s) regulate anthelmintics?
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FDA
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What are the NINE types of anthelmintics that we are studying in this course?
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1. Benzimidazoles
2. Imidazothiazoles (levamisole) 3. Tetrahydropyrimidines (pyrantel, morantel) 4. Macrolides or macrocyclic lactones (antiparasitics not antibacterials) 5. Isoquinolones (praziquantel and epsiprantel) 6. Cyclic depsipeptide (emodepside) 7. Benzenesulfonamide (clorsulon) 8. Amino acetonitriles (monepantel)—not in US YET 9. Spiroindole (derquantel)—not in US |
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name some benzimidazoles and their mode of action
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albendazole, fenbendazole, febantel, oxibendazole
affects tubulin |
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name some macrocyclic lactones and their mode of action
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Ivermectin, doramectin, eprinomectin, selamectin,
moxidectin, milbemycin affects glutamate gated chloride channels |
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name an imidazoithiazole and its mode of action
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levamisole
Acetylcholine agonist |
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name some tetrahydropyrimidines and their mode of action
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pyrantel, morantel
Acetylcholine agonist |
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name some isoquinolones and their mode of action
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praziquantel, epsiprantel
affects cell membrane permeability |
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name a cyclic depsipeptide and its mode of action
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emodepside
affects lactrophilin receptor |
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name a benzenesulfonamide
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clorsulon
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name an aminoacetonitrile and its mode of action
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monepantel
affects acetylcholine receptor |
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name a spiroindole and its mode of action
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derquantel
selective cholinergic agonist |
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resistance to one member of a group of anthelmintics, resistant to all in that group
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side resistance
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resistance to one group of anthelmintics conferring resistance to another group of anthelmintics
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cross resistance
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what word MUST you use in an essay regarding pesticide resistance?
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refugia
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what benzimidazole is approved for use in the most species?
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fenbendazole
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comment on the administration of benzamidazoles
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- Need to stay around for awhile to work (multiple doses in non-ruminants)
- fenbendazole needs to be given with food in small animals - Rumen acts as reservoir in ruminants |
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which benzamidazole is likely to be given to dairy cattle to manage a routine worm infestation and why?
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fenbendazole
no milk withdrawal time. Others are not approved for lactation or have long withdrawal times. |
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what is the spectrum of action of benzimidazoles?
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- nematodes: all life stages
- albendazole and fenbendazole also have activity against tapeworms and flukes |
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imidazothiazole and tetrahydropyrimidines
- examples (species) - spectrum of action - mode of action - administration - withdrawal time - safety |
- levamisole (ruminant, pig); pyrantel (horse, dog, cat, pig); morantel (bovine, Goats)
- adult nematodes - cholinergic agonists: depolarizing of neuromuscular junctions - oral, injection - meat, days; morantel has no withdrawal; the rest not for dairy - good; levamisole has most problems |
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macrolides
- examples - spectrum of action - mode of action - administration - withdrawal time - safety |
- avermectins: ivermectin, doramectin, eprinomectin, selamectin; milbemycins: milbemycin, moxidectin
- nematode adults and larvae; arthropods - binds to glutamate gated chloride channels: hyperpolarization of nn. and mm. - oral, SubQ, topical, sustained release (moxidectin) - withdrawal zero to weeks for meat; eprinomectin & moxidectin have no milk withdrawal; others not for dairy - safe. exceptions: ivermectin in collie breeds and moxidectin in horses; eco: ivermectin can delay fecal processing but low with interval dosing |
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isoquinolones
- examples - spectrum of action - mode of action - administration - safety |
- praziquantel, epsiprantel
- tapeworms and some flukes - tetanic contraction of muscles, probably from change of permeability of tegument to calcium - oral - safe |
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cyclic depsipeptidases
- examples (species) - spectrum of action - mode of action - safety |
- emodepside (cats only)
- nematodes - binds to presynaptic lactrophilin receptor causing flaccid paralysis - safe |
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benzene sufonamides
- examples (species) - spectrum of action - administration - withdrawal time |
- clorsulon (bovine); often combined with ivermectin
- bovine liver fluke - oral and injectible - not for dairy |
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piperazine
- species - spectrum of action - mode of action |
- pigs, birds, horses
- pigs and birds: ascarid nematodes; horses: small strongyles (not common) - anticholinergic: paralyze worms |
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amino acetonitriles
- example (species) - spectrum of action - mode of action |
- moneprantel (large animals) (not yet available in US)
- nematodes (especially those resistant to other anthelmintics) - AcCh receptor on muscle; hypercontraction of body and spasmodic contraction of pharynx |
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spiroindoles
- example - spectrum of action - mode of action |
- derquantel (in combination with ivermectin)
- nematodes - selective cholinergic anatagonist in mucsle; flaccid paralysis |
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benzimidazoles
- examples (species) - spectrum of action - mode of action - administration - withdrawal time - safety |
- fenbendazole (bovine, dog, horse, goat, pig); albendazole (bovine, sheep); oxibendazole (horse); oxfendazole (bovine); febantel (dog; cat product no longer available)
- nematodes; adult, larvacidal over longer periods, ovidical; tapeworms and flukes (albendazole, fenbendazole) - prevent microtubule assembly; secondary effect on some enzymes - oral - meat withdrawal days to weeks (albendazole longest at 27 d); milk: fenbendazole has no withdrawal time, but others not for dairy |
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the "skin" of a nematode is called what?
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cuticle
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what is the basic anatomy of a nematode?
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- cuticle surronded by hypodermis and longitudinal muscles
- pseudocoel with hemolymph (hydrostatic skeleton) - gut tube and sex organs seen in cross-section |
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describe the structure, organs, and neurotransmitters of the nematode nervous system
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- ganglia with longitudinal nerve cords
- papillae as tactile receptors - acetylcholine and GABA |
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describe the nematode digestive system
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- food depends on worm and location
- oral opening - buccal capsule - pharynx (important in taxonomy and ID) - intestine - anus in female; cloaca in male |
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describe nematode reproduction and sexual dimorphism
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- most dioecius (separate sexes)
- some are parthenogenic (diploid eggs that don't need fertilization to become an embryo) - females usually larger - males have spicules (used in ID) - females release eggs or larvae |
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how many molts does a nematode go through to become an adult?
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four: L1-L5
note, no molt for L5-->adult |
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name four superfamilies order strongylida
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Trichostrongyloidea
Strongyloidea Ancylostomatoidea Metastrongyloidea |
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name three genuses of order ascaridida
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1. Toxocara
2. Parascaris 3. Ascara - Baylisascaris (racoon) - Ascarida (avian) - Heterakis (avian) |
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Name 7 genuses of Trichostrongyloidea
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Oestertagia, Haemonchus, Trichostrongylus, Cooperia, Nematodirus, Dictocaulus, Hyostrongylus
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name four clinically important types of Strongyloidea
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Equine Strongyles, Cyathostomes, Strongylus (vulgaris), Oesophagostomum
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comment on the passage, development, and morphology of the ascarid egg
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- passed in fresh feces as a single cell
- larva develops up to L3 in the egg - take 2-4 weeks - the only worms with a thick shell and a single egg inside |
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pig ascarid genus and species, common name
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Ascaris suum
roundworm |
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Ascaris suum
- location of adult in the host - how long before egg becomes infective? - prepatent period |
pig ascarid (roundworm)
- small intestine - at least 3 weeks. (egg can be viable for years) - 6-8 weeks |
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Ascaris suum
life cycle |
pig ascarid (roundworm)
- eggs-->L3 in the environment - L3 is the infective larva in the egg - L3 hatches in the intestine and burrows through intestinal wall - hepatic portal to liver - burrow thorugh liver to bloodstream - bloodstrream to lungs - coughed up, swallowed - become adults in small intestine - eggs shed in fresh feces - prepatent period is 6-8 weeks |
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Ascaris suum Dx
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pig ascarid (roundworm)
Fecal exam |
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Ascaris suum clinical importance
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pig ascarid (roundworm)
- inflammation of liver ("milk spots") - liver condemnation - lesions regress after 4-6 weeks - dyspnea - secondary lung infection - low productivity - (rarely) block bile ducts, obstruct/perforate BVs |
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who is most at risk of developing disease from Ascaris suum infection and why?
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pig ascarid (roundworm)
- young pigs that are heavily infected. - immunity develops during 1st infection |
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Ascaris suum control and treatment, including drugs
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pig ascarid (roundworm)
- remove feces - kill eggs (very difficult: need flame, steam, lye) - treat prefarrowing sows - BZDs, pyrantel, macrolides, lavamisole, dichlovos |
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Ascaris suum zoonosis
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- respiratory disease in calves
- can infect humans |
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human ascarid Genus and species
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Ascaris lumbricoides
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ascarid of horses and other equids Genus and species
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Parascaris equorum
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Parascaris equorum
- prepatent period - most susceptible animals - clinical signs |
(horse ascarid)
- PPP 11-14 weeks - foals and young horses LARVAE - damage lungs through mechanical damage and inflammation - 2ndary infections - nasal discharge - unthrifty - may be permanent in severe cases ADULTS - low levels, no signs - unthrifty - pot belly - perforation or impaction in very heavy infection |
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Parascaris equorum Dx and Tx
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horse ascarid
- eggs in fecal float - numbers used to evaluate drug efficacy - all nematocidal anthelmintic effective - macrolides and FBZ for 5 days is larvacidal |
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Parascaris equorum environmental and drug control
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horse ascarid
- remove feces - clean stalls with 5% phenol solution - wash udders before foaling - treat at 8 weeks of age and monthly to every six months |
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how long do Parascaris equorum eggs require to be in the environment before they are infective?
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2 weeks
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what is the genus of the small mammal ascarids?
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Toxocara
(roundworms) |
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What is the prepatent period of Toxocara canis? How long do eggs take to become infective?
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(roundworms)
PPP is 5 weeks and 3 weeks after birth in congenital infections eggs infective after 3-4 weeks |
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how can Toxacara canis adults become dormant in the host and what predisposes the host to this condition?
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(roundworms)
- adults can migrate to tissues and become dormant in granulomas - older hosts with immunity have a higher prevalence |
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Why is the Toxocara canis prepatent period only 3 months in newborns, but 5 months in adults?
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(roundworm)
Because the somatic reservoirs activate 40-45 days after pregnancy, migrate transplacentally, and infect the liver of the developing fetus. |
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If puppies are infected with Toxocara canis at birth, why is the mother at risk?
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(roundworm)
The dam can acquire infection through coprophagia because she needs to lick her pups to stimulate defecation. |
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What are three common transport hosts of Toxocara canis
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(roundworm)
Rodents, birds, earthworms |
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Comment on the clinical signs with respect to worm burden in puppies infected with Toxocara canis
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(roundworm)
Light infections - no clinical signs Moderate to heavy: - diarrhea and constipation - colic and pot belly - vomiting - unthrifty, poor hair coat - death with heavy infection |
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what is the preferred drug for treatment of Toxocara canis in puppies and why
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(roundworm)
pyrantel because it is easy to administer and usually requires only one dose |
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what drugs are effective in the treatment of Toxocara canis infection?
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(roundworm)
pyrantel, macrolides, fenbendazole, febantel |
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Comment on the treatment of pregnant dams for Toxocara canis
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(roundworm)
It is off-label use - fenbendazole or macrolides |
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Toxocara canis Tx and control
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(roundworm)
- Treat lactating dams - Off-label treatment of pregnant dams - treat other dogs as needed or routinely - remove feces - wash surfaces with 1% bleach (doen't kill eggs, but removes sticky surface) |
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low long do Toxocara canis eggs take to develop in the environment to become infective?
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(roundworms)
3-4 weeks |
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Genus and species of cat roundworm
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Toxocara cati
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What are ways that cats can become infected with Toxocara cati
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(roundworms)
- direct from infective eggs - transport hosts (e.g. rodents) - transmammary (minor) - NOT transplacental |
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How is Toxocara cati treated and controlled?
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(roundworm)
same as Toxocara canis |
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comment on the zoonosis of Toxocara canis and T. cati
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can be transmitted to humans:
- visceral larva migrans - ocular larva migrans |
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what are the two syndromes of human toxocariasis?
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(roundworms)
- Visceral larva migrans (VLM) - Ocular larval migrans (OLM) |
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what are the symptoms of visceral larval migrans syndrome in human toxocariasis? Risk factors?
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- eosinophilia, fever
- hepatomegaly - respiratory signs - encephalitis (rare) Risk factors: age, pica |
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what are the symptoms of ocular larval migrans syndrome in human toxocariasis?
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- endophthalmitis
- chorioretinitis - badness |
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what are the major socioeconomic risk factors for human toxocariosis?
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- soil related occupation
- non-U.S. birth - poverty - educational level - lead level - household crowding take-home message: poor people |
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what is the role of contact with infected dogs in human toxocariasis?
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probably not great
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what is another less prevalent genus of roundworm that infects dogs and cats besides Toxocara?
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Toxascaris
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raccoon ascarid
- Genus and species - clinical importance and zoonosis - control |
- Baylisascaris procyonis
- causes visceral larval migrans in many species - severe CNS signs with fatailities in human puppies - rarely patent in dogs - treat captive raccoons |
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Name two avian ascarid genuses, their location in the host, and clinical signs
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1. Ascarida
2. Heterakis - transport host of blackhead in turkeys - weight loss - ruffled feathers - depressed |
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what is the common Stongylida superfamily in ruminants?
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Trichostrongyloidea
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what is the common Stongylida superfamily in Horses
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Strongyloidea
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what is the common Stongylida superfamily in small animals and humans?
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Ancylstomatoidea
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which superfamily of Strongylida does not have direct life cycles?
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Metastrongyloidea
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what does a stongylid egg look like?
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oval, thin shell, ball of cells inside
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what is the life cycle of most strongylids?
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- eggs laid in fresh feces
- L1 develops inside egg - L2 and L3 develop outside egg in the fecal mass and distributed into the environment by rain and other mechanical forces - L3 is ingested by host - does not migrate like ascarids - L3 - L5, adult in host |
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what factors favor the development of strongylid eggs from egg to L3? What factor favor the survival of L3?
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Development:
- warm temp (> 50 ºF) - moisture Survival: - cool temp - moisture |
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Explain hypobiosis in strongylids
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- L3 or L4 in the definitive host may become dormant after infection
- may be due to environmental factors or immunity - might be a part of the life cycle to adapt to seasonal climate changes |
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what is the "HOT complex?"
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common strongylids of large animals:
- Haemonchus - Ostertagia (Teladorsagia) - Trichostrongylus |
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what is the most important helminth that infects cattle?
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Ostertagia ostertagi (strongylid)
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brown stomach worm of cattle Genus and species
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Ostertagia ostertagi (strongylid)
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brown stromach worm common in small ruminants
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Ostertagia circumcincta
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What is the life cycle, including minimum and maximum prepatent periods, for Ostertagia spp.?
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(strongylid in ruminants)
- ruminant ingests L3 from pasture - larvae enter gastric glands for a minimum of several days - emerge into lumen and become adults - prepatent period of 21 days (max 4-6 months) |
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what are clinical signs of Ostertagia infection?
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(strongylid in ruminants)
- damage the abomasal wall - cell dedifferentiation and hyperplasia - nodules in gastric glands - loss of normal gastric gland function - Anorexia with moderate infection - Heavy infection: diarrhea, anorexia, weight loss, unthriftiness, hypoproteinemia (bottle jaw) |
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what are the two syndromes of Ostertagia infection and what causes each?
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(strongylid in ruminants)
- Type 1: accumulation of worms past pathogenic threshold - Type 2: large amount of worms emerging from hypobiosis |
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Type 1 Ostertagiasis:
- incidence risk - time of year - mortality risk - clinical signs |
(strongylid in ruminants)
- many susceptible animals affected - mid to late grazing season - few fatalities - diarrhea, weight loss |
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Type 2 Ostertagiasis:
- incidence risk - time of year - mortality risk - clinical signs |
(strongylid in ruminants)
- few animals affected - before major transmission season (when arrested larvae emerge) - high mortality - acute, severe diarrhea and dehydration |
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what are risk factors for disease resulting from Ostertagia infection?
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(ruminant strongyles)
Stressed animals: - nutritional - diseased - periparturient - other stresses (e.g. car broke down on I-81) |
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what is the most important small ruminant strongylid in the world?
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Haemonchus contortus
(strongylid) |
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If upon necropsy, you find worms in the abomasum of a cow, what worm is it likely to be?
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Haemonchus placei
(strongylid) |
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If a sheep or goat has anemia, what infection should be on your rule-out list?
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Haemonchus infection
(strongylid) |
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Haemonchus life cycle:
- prepatent period - effect of weather |
(strongylid of small ruminats and cattle)
- 2-3 week PPP - likes humid, warm weather - hypobiosis in cold weather |
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what strongylid species can can infect the stomach/abomasum of horses, pigs, and cattle?
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Trichostrongylus axei
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where in the host do most species of Trichostrongylus spp. infect? Clinical signs?
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- small intestine
- diarrhea in heavy infection |
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what strongylid species stays in the egg until L3?
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Nematodirus spp.
(a trichostrongylid) |
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lung worm Genus and type of worm
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Dictyocaulus spp.
trichostrongylid |
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trichostronglyid of the pig intestine
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Hyostrongylus
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equine strongyles are of what order and superfamily?
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Order Strongylida
Superfamily Strongyloidea |
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what are the two subfamilies of equine strongyles and their common names?
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- Strongylinae: large strongyles
- Cyathostominae: small strongyles |
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where do equine strongyles typically reside in the host?
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cecum and large intestine
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what is the life cycle of small strongyles (Cyathostomes), including the prepatent period?
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- L3 go to cecum, colon when ingested
- enter crypts of Liberkuhn and penetrate mucosa - develop or become hypobiotic - return to lumen to mature (up to 2 cm long) - without hypobiosis, PPP is about 6-14 weeks |
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Small strongyles--Cyathostomes clinical importance, including syndromes, signs, Dx
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- low numbers, no apparent effect
- larvae cause problems, not adults Acute (Type 2) cyathostomiasis: - rapid onset, fever - diarrhea - edema, hypoproteinemia - Dx: difficult; may see larvae in feces, but often negative fecal - hard to treat if there are large numbers of worms - double dose of fenbendazole for 5 days - moxidectin - not fully effective against hypobiotic larvae Chronic (Type 1) cyathostomiasis: - accumulation of large numbers in gut wall - inflammation and thickening of gut wall - colic - intermittent diarrhea - unthriftiness - Dx: high fecal egg count |
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what is unique about Strongylus vulgaris compared to other large stongyles? Pathogenesis and clinical signs?
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- L4 circulates in the blood stream
- can cause embolism - can damage vessel walls - thrombembolism - bowel necrosis - colic |
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what is the prepatent period for Strongylus vulgaris?
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6 months; 2 dewomings per year is enough
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what worm causes "pimply gut" in the large intestine of cattle, small ruminants, and pigs?
|
Oesophagostomum spp
(strongyloidea) |
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what is the best management practice for GI worm control in sustainable systems?
|
- don't eradicate worms
- keep worms at a low level - this keeps refugia up and resistance low Tools: RID: - Reduce parasite exposure on pasture - Immunity of the host - Drugs |
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what are some ways to reduce stongylid parasite exposure on pasture?
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- reserve pasture with fewest larvae for the most vulnerable animals
- reduce stocking density - remove manure - after grazing, harvest regrowth for hay - pasture rest - MIXED GRAZING |
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how can you use the immunity of the host to control stongyles?
|
- selective deworming - only use it on animals that need it the most
- culling (remember that worm burden is heritable) - select resistant animals - good nutrition |
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what anthelminthics are used most commonly in cattle and small ruminants?
|
- macrolides
- benzimidazoles - levamisole |
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what anthelminthics are used most commonly in horses?
|
- macrolides
- pyrantel - benzimidazoles |
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what superfamily and family do hookworms belong to and what are their hosts?
|
Superfamily Ancylostomatoidea
Family Ancylstomatidae hosts: small ruminants, ruminants, humans, other vertebrates |
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Ancylostomatoidea morphology:
- mouthparts - length - egg |
- large buccal capsule with teeth or cutting plates for bloodsucking
- 1-2 cm in length - typical strongylid egg |
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name three species of canine hookworms
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1. Ancylostoma canium***
2. A. braziliense 3. Uncinaria stenocephalia |
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name three species of feline hookworms
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1. Ancylostoma tubaeformae
2. A. braziliense 3. Uncinaria stenocephalia |
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Ancylostoma canium:
- site of infection in host - time from egg-->L3 - four routes of transmission |
(canine hookworm)
- small intestine (jejunum) - 2-7 days depending on temperature Routes of transmission: 1. Skin penetration 2. ingestion of larvae 3. Ingestion of transport host 4. Transmammary |
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Ancylostoma canium name three fates of the larvae in the dog.
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(canine hookworm)
1. Become adult in small intestine 2. Enter intestinal wall and later emerge 3. join somatic reservoir |
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Who is at most risk for Ancylostoma canium infection and what are the clinical signs?
|
(canine hookworm)
- most often seen in puppies - low worm numbers asymptomatic - diarrhea-melena - anemia, hypoproteinemia - unthriftiness - skin lesions |
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comment on Ancylostoma canium immunity
|
(canine hookworm)
- most exposed adults will develop immunity - there will be no disease unless immunocompromised, overwhelming parasite numbers, or malnourished |
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Ancylostoma canium Dx and Tx
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(canine hookworm)
Dx: fecal float. It is the only common strongylid egg in small animals Tx: canine anthelminthics except for piperazine. Repeat in 2-3 weeks. |
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Ancylostoma canium prepatent period
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(canine hookworm)
about 2 weeks after transmammary infection |
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what is Ancylostoma tubaeformae: host and common name?
|
feline hookworm
|
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what is the importance of Ancylostoma braziliense?
- hosts - how to they get into host - diseases |
- dogs, cats, and humans
- penetrate skin - cutaneous larva migrans |
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hookworm of ruminants:
- genus - how do they get into host - diseases |
- Bunostomum spp.
- penetrate skin - cutaneous larva migrans - large numbers can cause anemia, death |
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what is the common intermediate host for metastongyloides?
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molluscs
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name two species of metastongyloides and:
- hosts - where in the host is infection - disease |
1. Aleurostrongylus abstrusus
- many hosts - in the lungs - subclinical to serious respiratory disease 2. Parelaphostrongylus tenuis - white-tailed deer (preferred), camelids, sheep, goats - infects meningeal veins and venous sinuses - infects spinal cord and brain |
|
|
what are the two most effective ways to control metastrongyloidea?
|
- anthelminthics
- control mollusks (snails, slugs) |
|
|
what order and superfamily include heartworms?
|
Order Spirurida
Superfamily Filaroidea |
|
|
what is the typical intermediate host of the filaroids?
|
arthropods, such as insects
|
|
|
how could you tell a male adult heartworm from a female?
|
males have a coiled tail
|
|
|
what is the genus and species of heartworm?
|
Dirofilaria immitis
|
|
|
what geographic location will you typically find Dirofilaria immitis?
|
anywhere there are mosquitoes, especially the Gulf Coast. Mid-Atlantic, and Mississippi River states
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|
how long can microfilaria survive in the blood of the definitive host?
|
1 year
|
|
|
what is the life cycle for Dirofilaria immitis?
|
- mosquito bites dog and L3 crawl into bite wound, entering the host's bloodstream
- adults in the right heart and pulmonary arteries - females release microfilaria into the blood - mosquito takes a blood meal and the microfilaria develop up to L3 in the mosquito GI tract. - the cycle repeats |
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|
Dirofilaria immitis:
- how do L3 reach the arteries? - how long does it take them to reach the pulmonary arteries? - what is the prepatent period? - how long can adults live in dogs? |
- L3 migrate through the tissue and abdominal wall to thorax and enter the bloodstream
- Takes about 70 days to reach the pulmonary arteries - PPP = 190 days (about 6 months) - adults can live 5+ years in the dog |
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true or false: microfilariae produced in a dog must go to a mosquito to develop?
|
True
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what are the two major tests for heartworm infection?
|
- ELISA antigen test
- Knotts test (see microfilariae in the blood; only good for patent infections) |
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how long after Dirofilaria immitis infection is antigen detectable by an ELISA test?
|
5 months
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if a dog is not on heartworm medication and over 7 months of age, why should you test for heartworm infection before starting a prophylaxis regimen?
|
because if microfilariae are in high abundance, the heartworm preventative may kill them and cause significant problems such as anaphylaxis.
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how do monthly heartworm preventatives control heartworm infection?
|
They kill larvae acquired in the previous 45-60 days
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|
|
why could doxycycline be effective at treating a heartworm infection?
|
doxycycline kills Wolbachia, an obligate symbiont o fDirofilaria immitis.
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how do macrolides affect Dirofilaria immitis for the following life stages?
- microfilariae - L3 - "early" L4 - "late" L4 - adult |
- microfilariae: kill
- L3: kill - "early" L4: kill in 1-3 doses - "late" L4: kill with chronic monthly administration - adult: sterilizes most; NOT a treatment |
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why is heartworm testing in cats problematic?
|
- cats are rarely microfilariae-positive
- antigen test may be negative due to low worm numbers or immature worms - antibody tests have been developed |
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|
what is the most common manifestation of heartworm disease in cats?
|
HARD - heartworm associated respiratory disease
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|
why is heartworm difficult to treat in cats?
|
because the arsenicals are fatally toxic
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|
besides dogs and cats what other pet can get typical heartworm disease?
|
ferrets
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|
|
what causes "summer sore" in horses?
|
Habronema, a spiruid parasite of the equine stomach
|
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|
what is Thelazia, what does it infect, and where in the body of the host does it infect
|
Thelazia is a spiruid parasite of horses, ruminants, and dogs that infects the eye
|
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Physocephalus and Ascarops: what are they, what do they infect, where in the host do they infect, and what diesase to they cause?
|
spiruid parasites of pigs that infect the stomach and cause catarrhal enteritis
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|
|
Physaloptera:
- type of parasite - hosts - site of infection in the host - life cycle - Dx |
- spiruid parasite
- dog, cats, various wild animals - infects the stomach - beetle, cricket intermediate host - diagnose eggs in the feces |
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Habronema
- type of parasite - hosts - site of infection in the host - life cycle - clinical signs |
- spiruid
- infects horses - lives in nodules in the stomach - flies deposit larvae around mouth or other moist areas - larvae cause "summer sore" in other locations; can be mistaken for exuberant granulation tissue, neoplasia |
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Thelazia:
- type of parasite - hosts - site of infection n the host - life cycle - treatment |
- type of parasite: spiruid; "eye worm"
- hosts: horses, cattle, dogs - site of infection n the host: eye - life cycle: fly intermediate host - treatment: removal of worm |
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|
if a client finds dark brown worms in their toilet bowl, what are they likely to be?
|
Horsehair worms, which are not parasitic to mammals
|
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|
what is the genus name of whipworms and what is their location in the host?
|
Trichuris, located in the large intestine
|
|
|
Trichuris vulpis
- location in host - life cycle - prepatent period - Dx |
(canine whipworm)
- infects the cecum and colon - eggs develop infective stage in environment - dogs infected by ingesting infective eggs - 3 month PPP - eggs found in a fecal float, but this may be difficult because of the long PPP and intermittent egg shedding |
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|
canine whipworm genus and species
|
Trichuris vulpis
|
|
|
Trichuris vulpis
- Tx - Control |
(canine whipworm)
- Fenbendazole, febantel - give now, 3 weeks, and 3 months - remove feces - expose eggs to desiccation |
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|
comment on the zoonotic potential of Trichuris
|
(whipworm)
very host specific |
|
|
name three Genuses of capillarid worms (Order Enoplida)
|
1. Eucoleus
2. Pearsonema 3. Aoncotheca |
|
|
what are three species of capallarids that infect dogs and where in the body to they infect?
|
Eucoleus aerophilus - bronchial parasite (also cats)
Eucoleus boehmi - nasal Pearsonema spp - bladder (also cats) |
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what are three species of capallarids that infect cats and where in the body to they infect?
|
Eucoleus aerophilus - bronchial parasite (also dogs)
Pearsonema spp. - bladder (also dogs) Aoncotheca putorii - intestine |
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|
which capillarid species infect ruminants?
|
Aoncotheca spp.
|
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|
What is the basic life cycle of Trichinella?
|
- adult worms in SI or warm blooded animals
- females produce larvae that encyst in skeletal muscle of the same host - infection is from carnivorism of the tissue cysts |
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in what domestic animal in particular is Trichinella important?
|
pigs
|
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|
how are Trichinella cysts killed in meat so that they are not infective?
|
cooking and freezing
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|
what is the most common source of human Trichinella infection in the US?
|
Bear meat
|
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|
what is the genus and species name of equine pinworm, how is the host infected, how is it diagnosed and treated?
|
- Oxyuris equi
- infected by ingestion if eggs - fertilized females glue eggs to the perianal area - irritation from worm movement and egg glue - pruritis, "rat tailed" appearance - do the scotch tape test for eggs - treat with anthelmintics and clean blankets, etc. |
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|
Strongyloides stercoralis
- type of parasite - host - life cycle - Dx |
- a nematode of order Rhabditida
- dog small intestine - parthenogenic females release L1 - L1-->L3 in environment - infection through skin penetration - diagnosis with the Bearmann test |
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|
comment on the reproductive capability of tapeworms and flukes
|
They are hermaphrodites, but prefer to mate when possible
|
|
|
what is the common name for Cestodes?
|
Tapeworms
|
|
|
What are the two Orders of Class Cestoda?
|
Order Cyclophyllidea
Order Pseudopyllidea |
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|
with regards to the cyclophyllid type of tapeworms, comment on the following:
- mouth parts - number of intermediate hosts - egg morphology - prevalence |
- mouth parts: suckers
- 1 intermediate host - egg has hooks - prevalence: the most common type of tapeworm |
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with regards to the pseudophyllid type of tapeworms, comment on the following:
- mouth parts - number of intermediate hosts - egg morphology - prevalence |
- mouth parts: bothria
- 2 intermediate hosts - egg does not have hooks - prevalence: the less common type of tapeworm |
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|
what are the 3 regions of the body of the tapeworm and what is their appearance and function?
|
1. scolex - skinny part with suckers/hooks/bothira; attaches to gut wall
2. neck: distal to the scolex; region of cell division and production of stobila 3. strobila: collective term for all of the segments of the tapeworm, which are produced by the neck |
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from what do the stobila of a tapeworm grow and how are older/younger stobila positioned on the worm?
|
- the stobila (segments) grow from the neck
- the oldest segments are most distal to the scolex and neck |
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|
what are the three stages of devlopment for a tapeworm segment?
|
1. immature
2. mature (has repro organs of both sexes) 3. gravid: contains fully developed eggs |
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|
what is the general term used for a larval tapeworm in an intermediate host?
|
metacestode
|
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|
what is the most important Family of tapeworms?
|
Taeniidae
|
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|
comment on the eggs of Taeniidae:
- fecal exam - appearance and contents of egg - how they differ in appearance from genus to genus |
- may or may not be present in feces because they are passed in segments
- a thick brown "shell" with radial striations that look like a sunburst - contains an embryo called an oncosphere or hexacanth with 6 hooks - all eggs in this family are identical |
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|
what are the intermediate hosts and definitive hosts of Taeniidae?
|
- intermediate host is an herbivore or omnivore mammal
- definitive host is a carnivore |
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|
what are the four metacestode stages of Taeniidae in order of increasing complexity?
|
1. cysticercus
2. strobilocercus 3. coenurus 4. hydatid |
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|
what is a cysticercus and what is its gross appearance? What is an infection with them called?
|
a larval stage of the Taeniidae tapeworms
- fluid filled bladder - inverted, invaginated scolex - cysticercosis |
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|
comment what happens when a cysticercus is ingested? What does it produce?
|
(Taeniid tapeworm larva)
- the cyst is lysed, releasing the scolex, which attaches to the intestinal wall - one cysticticercus produces one adult becuase it has only one scolex |
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|
name the two genera of Taeniid tapeworms in the US that infect small animals
|
1. Taenia
2. Echinococcus |
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|
name seven species of Taeniid tapeworms with small animal definitive hosts.
|
1. Taenia pisiformis
2. Taenia taeniaeformis 3. Taenia hydatigena 4. Taenia ovia 5. Taenia multiceps 6. Echinococcus granulosis 7. Echinococcus multilocularis (5 Taenia and 2 Echinococcus) |
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what is the life cycle for Taenia pisiformis:
- eggs - intermediate host - larval stage - adult size |
- eggs shed in segments
- rabbit intermediate host - cysticercus in rabbit - adults up to 70 cm |
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what is the life cycle for Taenia taeniaeformis:
- eggs - intermediate host - larval stage - adult size |
- eggs shed in segments
- rodent intermediate host - strobilocercus in rodent - adults up to 2 m |
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|
comment on the clinical significance, Dx, and Tx of Taenia taeniaeformis and Taenia pisiformis
|
- minor, if any signs
- undesirable for clients - Dx: segments on animal or in environment - Tx: praziquantel, epsiprantel, FBZ; restrict hunting |
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Taenia hydatigena:
- definitive host - intermediate hosts - larva - practical importance |
(tapeworms)
- dog is definitive host - wild and domestic ruminants and pigs are intermediate host - larva are large cysticerci attached to peritoneal membranes - may cause concern at slaughter of food animals |
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|
Name the intermediate and definitive host for the following:
- Taenia ovis - Taenia serialis - Taenia multiceps |
(tapeworms)
- Taenia ovis: IH = sheep; DH = dog - Taenia serialis: IH = rabbit; SH = dog - Taenia multiceps: IH = sheep; DH = dog |
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|
comment on the importance of Taenia ovis
|
(tapeworms)
- cystecerci in sheep muscle - causes carcass condemnation - cases found in Canada and western US |
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|
Taenia multiceps
- hosts - larval stage - geographic location |
(tapeworms)
- IH = sheep; DH = dog - coenurus is the larval stage (fluid-filled bladder with many scoleces; 1 coenurus gives rise to many adults) - very rare in the US |
|
|
what is a coenurus?
|
larval stage of a Taeniid comprising fluid-filled bladder with many scoleces. 1 coenurus gives rise to many adults
|
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|
Echincoccus:
- two important species - size of adults - comments on larvae |
(tapeworms)
- Echincoccus granulusis and Echincoccus multilocularis - very small adults (compared to large Taenia) LARVAE: - mestacestodes undergo asexual mulitplication - hyatid cyst (like coenurus, but can form small cysts inside of the primary cysts) - thousands of scoleces can form |
|
|
Echinococcus granulosus
- hosts - location in definitive host - geographic location - how are eggs passed? - type of metacestode - location of metacestode in intemediate host |
(tapeworms)
- IH = sheep; DH = dog - location: rare in US, but common in sheep producing areas - in SMALL intestine of canid - eggs passed in tiny tapeworm segments - unilocular hyatid cyst, usually in the liver or lung of sheep |
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|
what is a hyatid cyst?
|
a fluid-filled membrane containing many cysts. Like a coenurus, but can form small cysts inside of the primary cysts that can contain thousands of scoleces.
|
|
|
how is Echinococcus granulosus treated in sheep? Dogs?
|
- sheep: difficult to treat, usually surgical
- dogs: praziquantel |
|
|
comment on the zoonisis of Echinococcus granulosus
|
(tapeworms)
- infective to humans by ingestion of eggs - larval stages can be found in multiple organs, including brain, lungs, liver, spleen, intestines, and bone marrow |
|
|
Echinococcus multilocularis
- geographic location - definitive hosts - intermediate hosts - larva |
- northern US and Canada
- IH = small rodents and humans - DH = fox, sometines dogs, rarely cats - larva is a multilocular hyatid cyst (grows by budding chambers, like cancer) |
|
|
what two species of Taeniidae have human definitive hosts?
|
- Taenia saginata
- Taenia solium |
|
|
Taenia saginata
- hosts - larvae - prevalence - Dx and Tx in intermediate host - Dx and Tx in definitive host |
(tapeworms)
- IH = beef; DH = humans - larvae are cysticerci in bovine muscle - low prevalence in the US, but increased risk of infections from immigration and occasional contamination of cattle feed (infected guy takes a dump in pasture) - Dx in cattle: slaughter inspection - Tx in cattle: none - Dx and Tx in humans: send them to a "real" doctor |
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|
Taenia solium
- hosts - location in definitive host - geographic distribution - larvae in normal intermediate host |
(tapeworms)
- IH = pig; DH = human - small intestine of human - worldwide, especially developing countries - larvae are cysticerci in pig muscle |
|
|
comment on the zoonosis of Taenia solium and Taenia saginata
|
(tapeworms from pigs and beef)
- if humans ingest eggs, they will host cysticerci - "cysticercosis, neurocysticercosis" - symptoms develop when cystecerci die in the nervous system - headache, confusion, seizures - leading cause on adult onset epilepsy - major problem in Mexico and Latin America |
|
|
In the US, what is the most common way that Taenia solium is trnsmitted?
|
usually human-human, not from pigs.
|
|
|
Non-Taeniad cyclophyllidean tapeworms:
- intermediate hosts - metacestode stage |
- IH = arthropods
- metacestode is called a cysticercoid (small cyst with invaginated single scolex) |
|
|
Dipylidium canium
- hosts - location in host - how is it acquired by definitve host? - prepatent period - Dx - clinical importance - Tx and control |
(non-Taeniid tapeworm)
- IH - fleas (rarely lice); DH = dogs and cats - in dog and cat small intestine - animal eats the flea and becomes infected - 2 week PPP - Dx: tapeworm segments in arianal area; rarely, egg packets in fecal - scooting, owners repulsed by moving segments, zoonotic (young children at greatest risk) - Tx: praziquantel - control: get rid of fleas |
|
|
Ruminant and Equine Tapeworms:
- Genera and hosts - location in host - intermediate host - how does infection occur? |
- Anoplocephala: horses
- Moniezia: ruminants - located in small intestine - cysticercoid in pasture mites after they ingest the eggs shed in feces of definitive host - definitive host infected when the mites are ingested while grazing |
|
|
Anoplocephala perfoliata
- definitive host - intermediate host - prevalence - location of adults - clinical signs - Dx and Tx |
(non-Taeniid tapeworm)
- DH = horse, IH = pasture mite - very common infection - adults in the cecocolic junction of horse - usually asymptomatic, but can cause inflammation and ulceration - Dx: fecal often negative; antibody test of limited use - Tx: praziquantel or 2X dose of pyrantel (part of a normal horse deworming schedule) |
|
|
Moniezia spp.
- definitive host - intermediate host - Dx - Tx |
(non-Taeniid tapeworm)
- DH = cattle; IH = pasture mites - Dx: segments in manure of young animals; eggs in fecal - Tx: benzimidazoles |
|
|
what is the usual intermediate host for avian tapeworms?
|
arthropods
|
|
|
for the pesudophyllidea tapeworms, what type of intermediate host is rquired?
|
an aquatic animal such as fish, amphibians, and reptiles
|
|
|
what do the eggs of pseudophyllidea look like in a fecal exam?
|
they look like fluke eggs except they have a cap
|
|
|
Spiometra spp.
- definitive host - common name - common intermediate hosts - geographic location |
(pseudophyllid tapeworm)
- DH = cats and sometimes dogs or wild animals - "zipper tapeworm" (because of the dots along the middle of its segments) - infected by eating amphibians or reptiles - common in SW US (where you find lots of amphibians and reptiles) |
|
|
Diphyllobothrium spp.
- common name - definitve hosts - intermediate hosts - prevalence |
(pesudophyllid tapeworm)
- broad fish tapeworm - DH = dogs, cats, humans, wildcarnivores - IH = fish - no longer seen in US except on House |
|
|
what is the common name for Trematodes?
|
flukes
|
|
|
how many orders of trematodes are clinically important?
|
(flukes)
2 |
|
|
for the trematodes relevant to mammals, comment on:
- morphology - segmentation - mouthparts - egg morphology - intermediate hosts |
(flukes)
- flat, leaf-shaped - unsegmented - usually 2 suckers - eggs with caps ("operculated") - usually 2 intermediate hosts - first intermediate host is always a snail |
|
|
for the trematodes important to mammals, what is the first intermediate host?
|
(flukes)
always a snail |
|
|
when a trematode egg hatches, what is released and what distinguishing anatomical feature do they have?
|
(flukes)
the egg hatches a miricidium, which has cilia note: this is what is ingested by the snail |
|
|
when a trematode leaves a snail, what is it called?
|
(flukes)
cercaria |
|
|
what is the name of the 2nd larval stage of Fasciola hepatica that is in or on the second intermediate host?
|
(flukes)
metacercaria |
|
|
what is the name of the trematode larval stage that the host ingests?
|
(flukes)
metacercaria |
|
|
what is the name (taxonomic and common) of the most clinically important trematode in the US?
|
(flukes)
- Fasciola hepatica - the liver fluke |
|
|
Fascolia hepatica:
- hosts - location in host - geographic distribution |
(liver fluke)
- ruminants - also dogs, cats, horses, humans, rodents - worldwide distribution |
|
|
Fasciola hepatica life cycle:
- adult location and egg release - egg --> larval stages - infection of adult - larval development - prepatent period |
(liver fluke)
- adults are in bile ducts, where they release their eggs - eggs deposited in water - eggs hatch into a miricidium - miriciduim infects snail - resulting cercaria encysts on vegetation and debris and become metacercaria - host infected by ingesting the metacecaria - once ingested, migrates through the intestinal wall and to the liver - they can crawl all over the liver and end up in bile ducts - PPP = 10-12 weeks |
|
|
what are the three areas in the US with the highest prevalence of Fasciola hepatica?
|
(liver fluke)
- gulf coast - pacific northwest - hawaii |
|
|
Clinical signs of Fasciola hepatica in cattle in sheep.
|
(liver fluke)
Cattle: - "chronic poor doing" - anemia, hypoproteinemia - weight loss - lower milk production - gradually develops immunity Sheep: - more severe disease, which can be fatal, because they don't develop good immunity |
|
|
Fasciola hepatica Dx
|
(liver fluke)
- history, clinical signs - SEDIMENTATION fecal exam (not very sensitive) - liver enzyme levels - sometimes, ELISA antibody test |
|
|
Fasciola Hepatica Tx and control
|
(liver fluke)
Tx: - routine Tx where common - treat when transmission is low, when worms are adults and smails are dormant - albendazole (not fenbendazole) and clorsulon Control: - management of premeses: drain, fence out marshy areas - near impossible to control snails |
|
|
besides Fasciola hepatica, what three other animal flukes are seen in the US?
|
Fascioloides magna:
- midwest - liver fluke of whitetailed deer - infects shep and goats - Dr. Zajac wants to fry one and eat it if one is found by a deer hunter Paramphistomum spp.: - rumen fluke occasionally seen in cattle and in jars in the MDL lab Paragonimus kellicotti: - cysts in the lung parenchyma of wild animals, dogs, and cats |
|
|
Paragonimus kellicotti
- geographic distribution - hosts - location in the host - intermediate hosts |
(a lung fluke)
- North America - wild animals, dogs, cats - cysts in the lung parenchyma - 1st IH = snail (obviously) - 2nd IH = crayfish/crawfish/crawdaddy - transport hosts may be involved |
|
|
Paragonimus kellicotti
- clinical importance - Dx - Tx |
(a lung fluke)
- may be asymptomatic or cause clinical respiratory disease (don't eat raw crayfish) - Dx: fecal - eggs may float but often distorted; sedimentation is the best - Tx: we don't need to know. Just look it up. |
|
|
what are Schistosomes?
|
A family of flukes that live in the veins of definitive host. Snails release cerceriae that can penetrate human skin, leading to "swimmer's itch"
|
|
|
what parasite causes "swimmer's itch?"
|
Schistosomes (a type of water-borne fluke)
|
|
|
Heterobilharzia spp.:
- hosts - how infection happens - location of parasite - clinical signs - Dx |
(a fluke)
- wild animals, occasionally dogs - eggs pass through SI tissues - infects mesenteric veins of the SI and liver - diarrhea, melena, hematochezia (frank blood in the feces), vomiting, lethargy - Dx: tricky. PCR available |
|
|
Name two species of flukes that act as disease vectors and information regarding them.
|
Nanophyetus salmincola
- intestinal fluke of carnivores in the Northwest - 2nd IH = fish - fluke carries Rickettsia, which causes "salmon poisoning" in dogs a fluke of bats is a vector of Ehrlichia risticii, which causes Potomac Horse fever. Horses are innocent bystanders |
|
|
what is the syndrome in human primates in which they think that they have parasites on their skin that makes them itch?
|
delusional parasitosis
|
