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189 Cards in this Set
- Front
- Back
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"intimate relationship btwn 2 heterospecific organisms, in which one (usually smaller) is metabolically dependent on the host" |
parasitism |
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"the degree to which a parasite species infects a single host species" |
host specificity |
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dirofilaria immitis is an [endoparasite/ectoparasite] with a [low/high] host specificity |
endoparasite
high |
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culex spp. (mosquitoes) are [endo/ecto] parasites with [low/high] host specificity |
ecto
low |
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"host in which parasite reaches sexual maturity" |
definitive host |
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"host in which the parasite is metabolically dependent to complete its life cycle" |
intermediate host (vector) |
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"host that the parasite does not normally infect, may or may not complete development" |
accidental host
*may be dead-end host |
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" a transport host, but parasite does not require to complete its life cycle" |
paratenic host |
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"an animal host that maintains a parasite population and has potential to transmit to human or domestic animal" |
reservoir host |
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life cycle where parasite does NOT require an intermediate host |
direct life cycle |
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life cycle where parasite requires an intermediate host |
indirect life cycle |
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"presence of an agent that has the ability to cause disease" |
infection |
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"the occurrence of dysfunction" |
disease |
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"capable of causing infection" |
infectious |
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infection/disease/infectious?
dog that shows no adverse symptoms to 2 female d. immitis in right vetricle |
infection only |
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infection/disease/infectious?
1,000 juvenile Haemonchus contortus were causing severe anemia in lamb |
infection & disease |
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infection/disease/infectious
cat suffering from large bowel D+ due to Tritrichomonas foetus pass active trophs in their stool |
infection & disease & infectious |
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infection/disease/infectious?
after using the bathroom, she was horrified to see she had passed several active proglottids of the beef tapeworm Taenia saginata |
infection |
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3 characteristics of macroparasites |
1. large - adult tapeworms, adult trematodes, most nematodes, arthropods, acanthocephalans
2. individuals do NOT multiply in/on host
3. dose-dependent |
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3 characteristics of microparasites |
1. small - protozoa, bacteria, viruses
2. individuals multiply in host
3. generally not dose-dependent |
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what is the active form of giardia? |
trophozoite |
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what is the infectious form of giardia? |
cyst |
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for Giardia sp. ______________ leads to pathology |
replication
*binary fission |
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describe life cycle of giardia sp. |
- cysts passed in feces *immediately infectious
- ingestion of cysts
- trophozoites in small intestine |
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pathology of giardia |
- causes irritation/death of epithelial cells & elicits immune response
- mal-digestion, mal-absorption, hypersecretion, increased transit
- enteritis & D+ |
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how do you diagnose giardia? |
- trophs on direct fecal
- cysts on fecal float (zinc sulfate)
- ***ELISA tests for dead OR alive antigen |
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treatment & control of giardia |
- fenbendazole, albendazole, metronidazole, quinacrine
- sanitation: remove cysts from envmt |
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challenge to controlling giardia |
sanitation - esp since cysts are infectious as soon as they are passed in the feces |
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scientific name for coccidia |
Eimeria sp. |
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life cycle of coccidia |
- unsporylated oocysts passed in feces
- sporulation in a few days
- ingestion |
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pathology of coccidia |
- destruction of host cells
- hemorrhagic D+
- concomitant infections may also play a role |
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which is more likely to show coccidial disease - confinement poultry - free-range poultry |
confinement |
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clinical signs of coccidia |
- asymptomatic to fatal hemorrhagic D+
- initial pathology may occur prior to oocyst shedding |
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how do you diagnose coccidia? |
oocysts in fecal float |
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treatment & control of coccidia |
- supportive therapy for symptoms
- sanitation: remove oocysts from evmt
- coccidiostats in production animals > prophylactic |
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challenge to controlling coccidia |
- sanitation
- assume infection = coccidiostats (production animals) |
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where do you see babesia sp? |
- troph in RBC
- intracellular form
- present with anemia |
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life cycle of babesia |
- ingested when tick takes blood meal > tick = intermediate host
- injected when tick takes a blood meal
*indirect transmission |
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routes of transmission of babesia |
- transplacental
- transfusion
- vector (tick)
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describe transovrian spread of babesia in ticks |
- parasite moves from female tick's cells to her eggs |
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describe transstadial spread of babesia in ticks |
- as tick develops & molts, the parasite continues in each new tick life stage
*making lots of baby ticks all with babesia! |
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pathology of babesia |
- destruction of host RBC = anemia
- acute disease = death or chronic illness
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clinical signs & diagnosis of babesia |
- hemolytic anemia, fever, jaundice, listlessness, anorexia, splenomegaly, lymphadenopathy
- intra-erythrocytic parasites on blood smear
- serology & PCR |
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treatment & control of babesia |
- imidocarb, berenil
- pest control: ticks |
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challenges to controlling babesia |
- pest control (tick vectors)
- sanitation - transfusion
- assume infection - transplacental |
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6 physical characteristics of nematodes |
1. cylindrical 2. dioecious (male & female) 3. complete gut (has anus) 4. cuticle (dead body wall they excrete) 5. pseudocoelom (false body cavity) 6. longitudinal muscles (whip around) |
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basic life cycle of pasture-borne nematodes |
1. adult worms in definitive host lay eggs 2. eggs passed in feces 3. L1 & L2 on-pasture feed on microbes 4. L3 - infective stage > retains L2 molt sheath (protection from desiccation) > non-feeding thus limited energy stores > ingested by host (deadly dew drops) |
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describe life cycle of haemonchus contortus |
- ova passed in feces
- L1 to L3 larvae in evmt
- L3 ingested via deadly dew drops while grazing |
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longevity of L3 in on-pasture nematodes: moderate temps + high humidity |
increased longevity (few months) |
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longevity of L3 in on-pasture nematodes: extreme heat + low humidity |
decreased longevity (dessication) |
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longevity of L3 in on-pasture nematodes: extreme cold |
decreased longevity (typically don't survive pasture through winter)
*CAN survive in host either as larvae or parasites |
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longevity of L3 in on-pasture nematodes: increased heat, activity |
decrease longevity due to increased use of energy stores |
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describe host immunity to worms |
- young are naive & fully subject to dose-dependent pathology - acquired immunity develops and decreases likelihood of overwhelming dose pathology - host immunity typically: > eliminates incoming larvae > sequesters larval worms in somatic tissue
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describe worms throughout a young host |
1. ingested infective larvae (lumen)
2. penetration into mucosa (development)
3. re-entry into lumen - adult worms |
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describe worms throughout a competent immune system |
1. ingested infective larvae (lumen)
2. penetration into mucosa (arrested/sequestered)
3. limited re-entry into lumen (fewer adults) |
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is host immunity against a specific worm species usually permanent? |
nope - new infections are NOT prevented |
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what is premunition? |
host immunity against a specific worm species is usually "active" only in the presence of adult worms |
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what causes post-treatment pathology when you elminate adult worms? |
reactivation of over-whelming population of arrested (hypbiotic) larvae |
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define dewormer resistance |
"a genetic sub-population of worms develop the ability to circumvent a SPECIFIC dewormer's mechanism of action" |
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T/F - dewormer resistance cannot be passed to offspring |
false - it is a genetic-linked phenotype and CAN be passed to offspring |
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3 ways that worms develop resistance to dewormer |
1. repeat/frequent exposure to the same one
2. under-dosing accelerates resistance dvpmt
3. frequent deworming eliminates susceptible worms, leaving only resistant ones |
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"the sub-population of susceptible worms" |
refugia |
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what is selective deworming? |
allowing non-clinical animals to remain infected allows sub-population of susceptible worms to remain dominant
*extends longevity of a particular dewormer's efficacy on a particular farm |
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3 main types of dewormer |
1. ivermectin
2. fenbendazole
3. pyrantel |
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"barber-pole worms" - why are they called that? |
Haemonchus contortus
- white ovaries wrap around red intestines |
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are haemonchus contortus dimorphic? |
yes |
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describe life cycle of Haemonchus contortus |
- prepatent in 3 weeks - stongyle ova passed in feces - infectious in 4-6 days pending evmt - L3 ingested while grazing |
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Haemonchus contortus has a [direct/indirect] life cycle |
direct |
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how is Haemonchus contortus transmitted? |
via deadly dew drops (ingestion of L3) |
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pathology of Haemonchus contortus |
- hemorrhagic anemia (severe pallor) - hypoproteinemia (facial edema - "bottle jaw) - morbidity & mortality - necropsy: pallor of organs; thin, non-clotting blood; abundant worms in abomasum |
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describe pathology of peracute disease of Haemonchus contortus |
- extremely lg # of immature worms - no eggs in feces - young exsanguinated before worms mature - severe hemorrhagic gastritis - may remove 1/5 circulating erythrocytes/day - sudden death from acute blood loss |
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describe pathology of acute disease of Haemonchus contortus |
- 1,000-10,000 worms - FEWC as high as 100,000 epg - young susceptible animals - anemia develops rapidly - expansion of erythropoietic response - may remove 1/10 circulating erythrocytes/day |
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describe pathology of chronic disease of Haemonchus contortus |
- 100-1,000 worms - FEWC < 2,000 epg - older animals - 100% morbidity but low mortality - depends on animal's erythropoietic capacity, iron and natural metabolic reserves - anemia/hypoproteinemia not as severe |
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clinical signs of haemonchus contortus |
- anemia - tarry feces - pale mucus membranes - bottle jaw *NOT D+ |
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how do you diagnose haemonchus contortus? |
- McMasters (FWEC) - treat at 1,000 worms > can check resistance & efficiacy also by testing 10-14 days later
- FAMACHA - grading of mucus membranes
- being a sheep or goat! |
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what is the grading scale on FAMACHA? which grade would you treat? |
1-5
3: check mcmasters to decide
4&5: treat |
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how do you treat haemonchus contortus? |
- dewormer (resistance is major issue) > single treatment to pregnant female to target their periparturient rise |
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how do you control haemonchus contortus? |
- pasture sanitation (not practical) - regular scheduled dewormer (resistance) - pasture rotation (2-6 mo rest) - co-species grazing - test & treat selectively (mcmasters/FAMACHA) |
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3 functions of McMasters testing |
1. make selective deworming decisions to deter resistance and promote refugia
2. id hosts that shed a lot of worms
3. determine dewormer efficiacy |
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challenges to controlling Haemonchus contortus |
- infective larvae on pasture
- hypobiotic larvae in host
- worm resistance to dewormers |
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are equine small strongyles dimorphic? |
yes |
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overview of life cycle of small strongyles |
- prepatent period is 3 months - ova passed in feces - L1 to L3 in 2 days to 2 weeks - L3 ingested during grazing
*direct |
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how are small strongyles transmitted? |
ingestion of infected larvae by horses |
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describe arrested phase of small stongyles |
- premunition inhibits devlopment - prepatency of arrested larvae as few as 18 days post-reactivation - post-treatment disease - preparturient rise targets young animals |
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pathology of small stongyles |
- mainly caused by emerging larvae - acute: severe enteritis, D+ & hypoalbunemia - post-treatment: severe enteritis, colitis, D+ & hypoalbuminemia - chronic: granulomatous colitisc |
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clinical signs of small strongyles |
- persistent D+ - edema - poor body condition - colic** |
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how do you diagnose small strongyles? |
- mcmasters FWEC (treat at 200-500)
*will only show adult burden, not disease causing emerging larvae
- check resistance in 10-14 days |
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control for small strongyles |
- pasture sanitation (removal of feces) - regular scheduled dewormer (resistance) - pasture rotation (months of rest) - co-species grazing - test & treat selectively |
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challenges to controlling small strongyles |
- infective larvae in pasture
- hypobiotic larvae in host
- worm resistance
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scientific name for hookworms |
Ancylostoma canium |
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morphology of hookworms |
- dimorphic (male has copulatory bursa)
- hooked anterior
- buccal cavity & teeth |
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transmission of hookworms |
- eggs to infective L3 in 5-7 days
- skin/oral penetration of L3
- ingestion of paratenic host with encysted L3 |
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prepatent period for hookworms |
15-18 days |
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describe arrested larvae of hookworms in host tissue |
- transmammary infections of puppies
- source for chronic hookworm disease
- premunition & larval leak |
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describe process of hookworm infestation in immuno-competent host |
1. L3 penetrate skin or oral cavity - migrate to liver then lungs - somatic migration - arrested in muscle tissues 2. ingestion of paratenic host - complete maturation in gut lumen |
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describe process of hookworm infestation in pregnant dog |
- L3 pentrate skin or oral cavity - migrate to liver then lungs - somatic migration - arrested larvae in muscle tissues - stress allows reactivation - to mammary gland for transmammary transmission to puppies |
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describe process of hookworm infestation in neonates |
1. peracute disease (ingested while nursing) - direct dvpmt to adults in the gut
2. acute disease (skin penetration) - migrate to liver then lungs - tracheal migration & swallowed back to gut |
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describe process of hookworm infestation in immuno-compromised dogs (old) |
- skin/oral cavity penetration - migrate to liver then lungs - somatic migration - arrested in muscle tissue - stress allows reactivation and migration to gut "larval leak" |
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pathology of hookworms |
- hemorrhagic anemia
- peracute, acute & chronic diseases
- zoonosis > cutaneous larval migrans > eosinophilic gastroenteritis |
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clinical signs & diagnosis for hookworms |
- anemia, edema, tarry feces, pale mucus membranes, blood D+
- check membranes in puppies
- fecal centrifugation |
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treatment for hookworms |
- dewormer (fenbendazole, ivermectin)
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how to treat peracute hookworm disease |
- deworm immediately
- may need iron supplement & blood transfusion
- deworm weekly due to re-infection from mom |
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how to treat acute hookworm disease |
- treat at 2-3 weeks old
- repeat treatment every 2 weeks until 2 months
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control of hookworms |
- sanitation - assume infection, especially puppies - heartworm prevention that kills hooks - regular fecal checks - prevent access to paratenic hosts |
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hookworm treatment plan for pregnant dogs |
- treat near parturition to target reactivated larvae
- daily from 40th day of gestation to 14th day of lactation |
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challenges to controlling hookworms |
- sanitation
- arrested larvae > transmammary transmission > larval leak
- paratenic hosts |
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scientific name for common roundworm |
Toxocara canis
*ascarid |
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morphology of ascarids |
- dimorphic (non-bursate) > spicules for copulation - large - 3 fleshy lips & cervical alae |
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describe direct life cycle of ascardis |
- prepatent 3 weeks if transuterine & 4-5 weeks if ingested - ova in feces - infective in 4 weeks - ingestion of egg **very resistant and long lived |
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prepatency of ascardis |
4-5 weeks via egg ingestion
3 week via transuterine |
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describe process of ascarids immuno-competent dog |
- eggs ingested & hatch in stomach - penetrate gut & migrate to liver - lungs - somatic migration - arrested larvae in muscle *adult worms in gut mostly from ingesting paratenic hosts |
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describe process of ascarids in pregnant dog |
- eggs ingested & hatch in stomach - penetrate gut & migrate to liver - lungs - somatic migration - arrested in muscle - stress causes reactivation and travel for transplacental transmission - transmammary if infected during preg. |
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describe process of ascardis in neonates |
1. transplacentral transmission in utero - to liver - lungs - trachea - coughed & swallowed - complete maturation in gut 2. ingested from evmt - hatch in stomach - penetrate gut wall and go to liver then same |
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pathology of ascarids |
- gastroenteritis
- zoonosis > visceral/ocular larval migrans |
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clinical signs of ascarids |
- abdominal pain - potbellied conformation - poor coat condition - fetid mucoid D+ |
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diagnosing ascarids |
- adult worms in feces or vomit
- fecal exam |
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treatment for ascarids |
- deworm (fenbendazole, ivermectin)
- treat puppies at 2-3wks & repeat every 2 weeks until 2 months
- treat pregnant animals leading up to delivery |
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control of ascarids |
- sanitation - assume infection in puppies - heartworm preventive that covers ascarids - prevent access to paratenic hosts |
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challenges to controlling ascarids |
- sanitation (very long-lived)
- arrested larvae (transuterine)
- paratenic hosts |
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what kind of worms are trematoda? |
flukes |
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overview of Fasciola hepatica |
- large, leaf-like, liver/bile duct flukes
- small anterior suckers
- dendritic intestines, testes & ovaries |
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definitive hosts for Fasciola hepatica |
cattle, sheep, goats, camelids |
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1st intermediate host of Fasciola hepatica |
pond/puddle snails |
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2nd intermediate host of Fasciola hepatica |
metacercaria
- aquatic or semi-aquatic vegetation |
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describe young flukes of Fasciola hepatica |
- migrate from intestine to liver - migrate through liver to bile duct (mature) - prepatent period = 2 months - entire life cycle = 3-6 months |
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geographic distribution of Fasciola hepatica |
- gulf coast, esp. FL
- pacific northwest |
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pathology of Fasciola hepatica - acute |
- due to migration of young flukes to liver
- severe liver damage, hemorrage, inflammation
- sudden death, esp. in sheet |
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pathology of Fasciola hepatic - chronic |
- due to adults in bile duct - loss of condition, weakness, hemolytic anemia, hypoproteinemia - liver fibrosis - stenosis of bile ducts - usually result in liver condemnation |
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clinical signs of Fasciola hepatica |
acute: abdominal pain, unwilling to move, sudden death
chronic: weakness, anemia, edema, bottle jaw |
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diagnosing Fasciola hepatica |
- fecal sedimentation
- liver enzyme analysis
- necropsy
- herd history |
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treatment for Fasciola hepatica |
- clorsulon (curatrem)
- albendazole
*neither are licensed for breeding dairy cattle |
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control for Fasciola hepatica |
- snail control (molluscicides; drain pastures)
- grazing control (restrict access to wet areas)
- strategic drug control **Ivomenc Plus (ivermectin + clorsulon) |
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zoonosis of Fasciola hepatica |
1. human fascioliasis - europe, africa, cuba, south america, USA
2. halzoun - ingestion of raw liver; egg attaches to naso-pharynx and has to be removed - middle east |
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describe Dicrocoelium dendriticum |
- lancet fluke - translucent, lancet-shaped bile duct fluke - ventral sucker in anterior half of body - glodular tandem testes posterior to ventral sucker, globular ovary posterior to testes |
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definitive host for Dicrocoelium dendriticum |
ruminants, pigs, deer, rabbits, humans |
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1st intermediate host of Dicrocoelium dendriticum |
terrestrial snail |
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2nd intermediate host of Dicrocoelium dendriticum |
metacercaria - ants
*ingest slimeball with larval fluke |
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describe young flukes of Dicrocoelium dendriticum |
- migrate from intestine to liver - migrate to bile ducts & mature - prepatent period = 50 days - adults can live 6 years or longer |
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pathology of Dicrocoelium dendriticum |
- non-pathogenic in younger animals
- bile duct hyperplasia, hepatic cirrhosis
- slow chronic progressive disease causing decreased productivity in older animals |
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diagnosing Dicrocoelium dendriticum |
- edema, emaciation in older stock
- ova in sedimentation
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geography of Dicrocoelium dendriticum |
widely distributed around the world - northeast US & canada |
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treatment for Dicrocoelium dendriticum |
albendazole in high doses |
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control of Dicrocoelium dendriticum |
- eradicate ant hills & snails (not feasible) |
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general classification name for tapeworms |
cestoda |
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2 general flatworm characteristics regarding digestions |
1. lacks digestive tract
2. absorbs food directly across tegument |
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3 parts of tapeworm body |
1. scolex - holdfast organ - suckers 2. neck - germinative region produces segments 3. strobila - series of maturing segments or proglottids |
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overview of Taenia pisiformis |
- large tapeworm of dogs
- scolex w/non-retractable armed rostellum & 4 suckers
- strobila has rectangular proglottids |
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definitive host of Taenia pisiformis |
dogs, fox, coyote, wolf |
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intermediate host of Taenia pisiformis |
rabbits or squirrels |
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describe young tapes in Taenia pisiformis |
- attach to intestinal lining & develop into mature tapeworms
- prepatent period = 56 days |
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geographic distribution of Taenia pisiformis |
worldwide |
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pathology of Taenia pisiformis |
- none (except in mal-nourished hosts)
- client worry |
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clinical signs of Taenia pisiformis |
- segments presented by clients
- occasionally dog drags tail to no symptoms
- dietary history of eating rabbits |
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diagnosing Taenia pisiformis |
- segment squash
*rectangular segments with single eggs |
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treatment for Taenia pisiformis |
- praziaquantel (doncit)
- epsiprantel (cestex)
****NOT ivermectin |
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control for Taenia pisiformis |
restrict access to rabbits |
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is Taenia pisiformis zoonotic? |
nope |
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what is the most common tapeworm in cats & dogs? |
Dipylidium caninum |
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definitive host of Dipylidium caninum |
canids & felids |
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intermediate host of Dipylidium caninum |
fleas & lice |
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describe young tapes of Dipylidium caninum |
- attach to intestinal lining and mature
- prepatent period = 21 days |
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geographic distribution of Dipylidium caninum |
worldwide |
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pathology of Dipylidium caninum |
- none (except in mal-nourished pets)
- client worry |
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clinical signs of Dipylidium caninum |
- owner brings in segments (no signs)
- occasionally will drag tail
- observation of fleas
- history: lack of flea control |
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diagnosing Dipylidium caninum |
segment squash
- oval segment with egg packets |
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treatment for Dipylidium caninum |
- praziquantel (droncit)
- epsiprantel (cestex)
***NOT ivermectin |
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control for Dipylidium caninum |
flea control |
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is Dipylidium caninum zoonotic? |
yes - children can be infected via ingestion |
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general arachnid characteristics
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- ornate or inornate scutum covers full dorsum of males but only anterior of females
- gnathostome (capitulum) projects anteriorally |
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3-host tick life cycle
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- engorged female drops off 3rd host & lays eggs
- eggs hatch in evnmt (6 legs) - larvae attack & feed on 1st host - larvae drop off & molt to nymphs (8 legs) - nymphs attack & feed on 2nd host - nymps drop off & molt to adults - adults attack, mate & feed on 3rd host |
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amblyomma americanum
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lone star tick
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rhipicephalus sanguineus
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brown dog tick or kennel tick
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dermacenter variablis
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american dog tick
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ixodes scapularis
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black-legged tick or deer tick
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describe 2-host tick life cycle
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- engorged female drops off 2nd host & lays eggs
- eggs hatch in evnmt (6 legs) - larvae attack & feed on 1st host - larvae molt to nymphs on 1st host - nymphs drop off & molt to adults - adults attack, mate & feed on 2nd host |
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describe 1-host tick life cycle
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- engorged female drops off host & lays eggs
- eggs hatch in evmt - larvae attack host - larvae feed on host; molt to nymphs; molt to adults; mate & feed on host |
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tick associated pathology
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- tick paralysis; toxicosis; blood loss
- wound production: bacterial infections - damage to hides *disease transmission |
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8 reasons why ticks are excellent vectors
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1. persistent feeders (hard to dislodge)
2. slow feeders (transmission; dispersal) 3. low host specificity 4. longevity (long lifespan) 5. transovarian transmission 6. transstadial transmission 7. hardy 8. high fecundity |
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nonchemical control of ticks
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- brush/vegetation removal ($$ & labor)
- resistant cattle breeds (brahman) - vaccines - predators & parasites |
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chemical control of ticks
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- dips
- whole body spray - topicals & dusts - insecticide impregnanted in collars & tags - injectants & acaricide boluses (systemics) |
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overview of mallophagan lice
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- head wider than body
- chewing mouth parts - feed on fur, feathers & epidermal debris |
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overview of anopluran lice
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- head narrower than body
- piercing/sucking mouth parts - feed entirely on blood |
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louse life cycle
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- eggs (nits) cemented to hair/feathers and hatch in 1-1.5 weeks
*NOT affected by insecticides - nits hatch & go through series of nymphal stages before becoming adults |
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how are lice transmitted?
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1. close contact
2. grooming tools 3. horse tack; pet collars; clothes |
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lice are typically most common in what season?
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winter
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pathology of mallophagan lice
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- feed on fur/feathers/epidermal debris
- irritation > restless, stressed animals > bite/scratch themselves > decreased productivity |
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control of mallophagan lice
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mainly topicals
- sprays, dips, pour-ons, shampoos |
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anopluran lice pathology
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- feed entirely on blood
> heavy infestations = anemia & death - irritation > restless, stressed, self-damage, decreased productivity |
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control of anopluran lice pathology
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- topicals
> sprays, dips, pour-ons, shampoos - systemics (subQ ivermectin) |
