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33 Cards in this Set
- Front
- Back
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What parasite characteristics influence infection? What about host?
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- parasite: level of exposure including hosts with infection and environmental conditions
- host infection influenced by behavior, immunity, and genetics - immunity can be natural and acquired, influenced by host age, gener, reproductive, nutritional status - genetics influences behavior and immunity |
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What is the "70-30" rule?
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- worm population isn't normally distributed but rather overdispersed
- smaller portion of the population has the largest portion of wormload - 30% of population has 70% of worm load - most animals maintain low to moderate parasite burdens |
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What immune responses occur during parasitic infections? Which of those are dominant?
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- Th1 and Th2 respond to parasitic infections, Th2 appears to most dominant
- Eosinophils typically elevated as well - normal immunity limits reinfection, reduces growth, and reproduction of parasites |
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What are the general characteristics of Phylum Platyhelminthes?
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- includes mostly flatworms
- parasites are hermaphrodites - definitive host dx by presence of eggs, intm. host more difficult to dx - include tapes and flukes |
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What are the general characteristics of Class Cestoda? What orders are included in this class?
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- includes tapeworms that are segmented and relatively long, body is divided into 3 regions
- adults live in host GIT - generally the small intestine! - worms have no intestine, instead absorb nutrients across surface - require at least 1 intm. host - includes order Cyclophyllidea and Pseudophyllidea - Cyclophyllidea most common in domestic animals and humans, most imp. family in this group is Taeniidae, all others called non-Taeniads - Pseudophyllidea are common in fish and animals that eat them |
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What are the general characteristics of Class Cestoda? What orders are included in this class?
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- include the scolex, neck, and strobila
- scolex includes the suckers or hooks that attach to gut wall - neck is the region of cell division that gives rise to new segments called proglottid - strobila is a collective term for all segments, oldest segments at post. end, these will be larger |
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What is contained within each tapeworm segment?
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- each segment contains at least one set of all repro organs from both sexes
- each segment matures - once matures, segment fills with eggs or becomes gravid |
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What is the general term for a larval tapeworm?
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Metacestode
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What are the characteristics of Family Taeniidae within order Cyclophyllidea?
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- include Taenia spp. and Echinococcus spp.
- all members of the Taeniidae family have similar eggs, eggs can be found in fecal exam but not always present despite infection - definitive are typically mammalian predators and intm hosts are typically herbivores or omnivores - ALL will be vertebrates - gravid segments shed and pass from the host - larval stages more imp. for dz |
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What hosts differences exist between Taeniidae and non-Taeniads?
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- non-Taeniads have invertebrate intm. hosts and vertebrate def. hosts
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What are the two important types of larvae in the family Taeniidae?
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- include Taenia spp. and echinococcus spp.
- all members of the Taeniidae family have similar eggs, eggs can be found in fecal exam but not always present despite infection - definitive are typically mammalian predators and intm hosts are typically herbivores or omnivores - ALL will be vertebrates - gravid segments shed and pass from the host - larval stages more imp. for dz |
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Describe the cysticercus larvae.
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- most common stage of Taeniidae infections
- sort of like a fluid filled bladder that has been inverted - scolex has been invaginated - infection with this is cysticercosis, 1:1 ratio of larvae to adult tapeworm |
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What are the two most common Taenia seen in small animal practice? What are the intm. hosts? What is the dx and trt?
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- T. pisiformis infects dogs and taeniaeformis infects cats
- THESE ARE VERY HOST SPECIFIC - eggs are shed in segments Rabbits are the intm host for T. pisiformis and rodents for T. taenieformis - both intm. host contains cysticercus larvae - dx with centrifugal fecal floatation, but cause very few clinical problems - trt includes praziquantel, epsiprantel, and FBZ |
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What other Taenia spp. are found in dogs? What are the intm. hosts?
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- T. hydatigena requires the dog as a def. host
- Intm. host includes wild animals, domestic ruminants, pigs - cysticerci attached to peritoneal membranes |
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What parasite requires a dog/sheep cycle? What are the symptoms? How does this Taenia differ from the others?
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- T. multiceps requires a dog/sheep cycle but is uncommon in the US
- this taenia has a different larval stage called coenurus, it's also a fluid filed bladder, membrane forms many scoleces, this larval stage doesn't have a 1:1 ratio instead 1 larvae gives rise to multiple adult tapeworms - in sheep this tape loves to form a cyst in the brain |
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What are the general characteristics of Echincoccus spp.?
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- E. granulosus and multilocularis
- Hydatid cyst larval stage, def host eats eggs in feces, intm host must eat infected viscera - zoonotic potential |
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Describe the general characteristics of E. granulosus including clinical problems and the life cycle.
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- intm. host (generally sheep) contain unilocular hydatid cysts esp. common in liver and lung, infection occurs when they eat infected feces, aseuxal reproduction occurs in intm. host
- dogs are generally def host, infection occurs when they eat contaminated viscera, sexual reproduction in def host - generally uncommon the US, trt with praziquantel in dogs, remove sheep carcasses - zoonotic potential, humans become infected when they ingest hydatid cyst of infected tissues |
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What the general characteristics of E. multilocularis? include the life cycle, hosts, etc.
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- fox is generally def. host, sometimes dog, RARELY the cat
- intm. host is generally small rodents, - again intm. hosts are infected with infected feces (except humans - infected with hydatid cyst) - multilocular hydatid cyst instead of unilocular - zoonotic parasite, difficult to get rid of in humans - dx is difficult in dogs, treat with praziquantel |
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What spp. of Taenia requires humans as a def. host and is contracted by way of infected beef? Describe the general characteristics.
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- T. saginata uncommon in the US
- Cysticerci larvae are in bovine muscle, cattle contract through feces infected with human egg segments - Dx in cattle during slaughter inspection - humans experience weight loss but clinical signs really aren't that severe - no trt in cattle |
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What spp. of Taenia requires humans as a def. host and is contracted by way of undercooked pork? Include the symptoms and life cycle.
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- T. solium is a human porcine life cycle parasite, occurs worldwide, but esp developing countries
- the adult worms like T. saginata don't really cause any problems - cysticerci is what causes problems including cysticercosis and neurocysticercosis - clinical signs include headache, confusion, seizures, also causes adult onset epilepsy |
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What are the general characteristics of non-taenid Cyclophyllidean tapeworms?
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- belong to several different families but is unimportant
- use arthropod intm. hosts as opposed to mammalian hosts - larval/metacestode stage is a cysticercoid, no fluid filled bladder, invaginated single scolex |
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What the general characteristics of E. multilocularis? include the life cycle, hosts, etc.
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- most common tapeworm of dogs and cats in the US, cats and dogs are def host.
- fleas are intm. host, uncommonly lice, flea larvae ingest eggs packets from gravid segments, cysticercoid larvae develop in body cavity - infection in def. host occurs following INGESTION of flea which contains the cysticercoid, 2 wk PPP - will generally see tapeworm segments in perianal area, eggs packets not usually seen in fecal sample because packets aren't broken, multiple eggs are present within packet - infections are usually non-pathogenic however this parasite is zoonotic especially for young children - trt with praziquantel and epsiprantel, also requires using flea control |
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What common horse non-taeniad tapeworm we discussed in class? Describe the general characteristics, life cycle, etc.
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- Anoplocephala perfoliata, common in the Eastern US esp.
- pasture mites are in the intm. host, they ingest infect egg packets - horses ingest infected mites - Usually asymptomatic, short tapeworms cluster at ileocecal junction, occasionally causes inflammation, ulceration, in severe cases perforation and intussusception - dx is difficult, segments not seen in manure - trt with praziquantel 1-2x annually, infection can't be prevented |
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What is the common ruminant tapeworm? Describe general characteristics and trt.
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- Moneizia spp., very common
- often see segments in manure, esp in young animals, eggs in fecal exams as well - no effects really on production - trt with BZD's |
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What are the general characteristics of Order Pseudophyllidea?
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- life cycles are complex, at least one aquatic animal as intm. host
- have sucking grooves instead of round suckers - segments aren't passed in feces, eggs in feces appear more like fluke eggs, have an operculated cap - relatively unimportant |
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What are the general characteristics of Phylum Platyhelminthes, Class Trematoda?
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- commonly referred to as flukes, clinical important ones belong to Order Digenea
- another group Monogenea are important parasites of fish |
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Describe the characteristics of Order Digenea. Include life cycle, hosts, etc.
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- leaf shaped, unsegmented, 1-2 suckers
- usually needs two intm. hosts, first one is always a snail - operculated eggs passed in feces, produced by adults - larval stage is called miricidium, eggs hatch in water before larval stage, larvae swim to specific snail host - land snails ingest eggs - asexual repro in the snail - next stage is cercaria which is out of the snail, either swims to next host and or is ingested on land, stage within second intm. host is metacercaria - def host ingests metacercaria |
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What are the flukes of interest in the US?
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- regionally: Fasciola hepatica and Nanophyetus salmincola (small animals)
- sometimes will see Fascioloides magna in large animals - sporadic cases of Paragonimus kellicotti |
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Describe the life cycle characteristics of Fasciola hepatica.
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- adults reside in liver and bile ducts of hosts
- ruminants most commonly, but also dogs, cats, horses, humans, rabbits - adults release eggs in the bile ducts, eggs are passed in the feces, hatch in aq. environ. - miricidium is first larval stage, uses a specific snail host for first intm. host, asexual repro occurs - cercaria is the next larval stage which migrates from snail host and forms a cysts in the environment and becomes metacercaria - metacercaria can be ingested and infect def. host - larval metacercaria migrates through intestinal walls to liver, migrate through liver for a few weeks and then enters bile ducts to mature, PPP is 10-12 wks |
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What is the clinical important of F. hepatica? Where is found geographical and how is it dx?
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- cattle: chronic poor doing including anemia, hypoproteinemia, weight loss, decrease milk production, immunity will gradually develop enough to rid the parasite
- small ruminants: more severe clinical dz, greater liver damage, less long term protective immunity - found commonly in Gulf Coast states, HI, Pacific northwest, specific to spp. of snail found there - some zoonotic potential - dx: history, clinical signs, fecal exam with sedimentation but not accurate, liver enzyme levels, sometimes ELISA |
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How is F. hepatica treated and controlled?
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- treat clinically infected with Albendazole and closulon, in endemic regions routine treatments occurs
- manage drainage areas |
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Describe the characteristics including clinical importance, trt, etc of Paragonimus kellicotti.
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- eggs are passed in feces of def. host, first intm = snail, second = crayfish
- occasionally transport hosts such as rats involved - generally asymptomatic but can respiratory signs - dx by fecal exam but not the best, sedimentation seems to be the most accurate - very high dose praziquantel can be tried, 14-21 d of FBZ also - zoonotic, DON'T eat raw crayfish |
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What are the two dz's that flukes serve as dz vectors for.
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- Nanophyetus salmonicola: intestinal fluke of bears, minks, dogs in Pacific Northwest, second host is fish, when dogs eats fish, fluke is ingested and the rickettsia bacterial dz causes salmon poisoning which is extremely deadly
- Ehrlichia risticii: fluke of bats carry this, bats are def host, snails and insect larvae are intm. hosts, horses are innocent bystander, "Potomic Horse Fever" |
