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40 Cards in this Set
- Front
- Back
problems caused by parasites
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compete for food ingested
mechanical obstructions suck/consume body fluids feed on solid tissue cause pressure atrophy cause allergic reactions destroy host cells produce toxic substances carry disease or other parasites stimulate formation of cancer reduce hosts resistance to otehr diseases and parasites |
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parasite
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an organism that lives upon or within another living organism
at the hosts expense, the parasite gains some advantage |
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facultative parasite
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organism that is usually freeliving that may develop a parasitic existence in some hosts
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incidental/accidental parasite
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a parasite found in a host different from the one it usually lives in
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aberrant/erratic parasite
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found in a different organ than normal
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pseudoparasite
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living organism or inanimate object that may be mistaken for a parasite
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host
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an organism in a parasitic relationship that provides refuge and nourishment for another organism
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definitive host
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host in/on which a parasite acheives sexual maturity
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intermediate host
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harbours an asexual, immature or larval stage of a parasite
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transport host
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type of intermediate host in/on which a parasite survives without undergoing further development
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reservoir host
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host from which an infeciton, parasite or disease may be passed onto another species
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direct life cycle
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parasite requires only one host to complete its life cycle
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indirect life cycle
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parasite requires more than one host species to complete its life cycle
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parasitosis
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parasite is present and is causing lesions or signs of disease
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somatic migration
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migration of larvae through the body
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parasitiasis
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parasite is present and is potentially pathogenic but is not causing signs of disease
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prepatent period
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time from the point of infection until a specific diagnostic stage can be recovered
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hypobiosis
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a temporary halt in the parasitic phase of development at a specific point in the nematode life cycle
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patent infection
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causitve agent can be detected or is shed
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occult infection
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organism is present in the host but cannot be detected and is not being shed
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characterisitcs of roundwords
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free living or parasitic
unsegmented posess an alimentary canal have male and female direct or indirect life cycle 1mm to 1m no circulatory or respiratory system |
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what is the cuticle
2 mods |
thin layer covering the worm
can be modified 1. cervical alae-lateral flattend extensions along anterior ends 2. copulatory bursa-lateral flattened extensions at posterior end assist males in mating |
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digestive tract of nematodes
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long, straight tube
mouth-lips-buccal cavity-esophagus-esophago intestinal valve-intestines- +/- ceca-rectum/cloaca-anus |
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oviparous
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female passes eggs in a morula stage
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ovoviviparous
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female passes eggs with a 1st stage larvae
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larviparous
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female retains the eggs in the uterus until they mature and hatch and then passes live 1st stage larvae
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4 egg types
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ascarid
tichostrongyle/strongyle trichelloid/trichoroid spiruloid |
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ascarid eggs
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thick shelled, round to oval and contain morula
outer shell may appear rough or pitted |
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trichostrongyle
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hookworm eggs
thin shelled, contain a morula stage |
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trichelloid
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lemon shaped
bipolar plugs morula |
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spiruloid
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larvated when passed by host
smooth, thick shelled |
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nematode life cycle
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typically 7 stages
egg-> 5 larval stages 5th is an immature adult stage molt between each larval stage |
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types of transmission
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ingestion
transplacental transmammory predation of transport host invasion through skin |
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benzimidazoles
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interfere with energy metabolism of the worm
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imidazothiazoles
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paralysis of parasite
ascarids, strongyles, whipworms and hookworms |
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organophosphates
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narrow range of safety
can cause neurologic damage to patient stay away from for hearthworms |
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piperazine
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very safe
blocks neuromuscular transmission in the parasite only ascarids |
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avermectins
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ivermectin (heartgard)
toxic reactions in shelties, collies and collie X's used for heartworm prevention |
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praziquantel
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works on all cestode spp
-increases the cestodes cell membrane permeability (droncit) |
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visceral larval migrans
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L2 eggs ingested by humans hatch and migrate through intestinal wall and may end up in other tissues
causes a variety of clinical signs:: blindness, enlarged liver, fever, weight loss inappetence |