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48 Cards in this Set
- Front
- Back
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what are the general features of order Ascarida?
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eggs are thick-walled, distictive, contain single cell; very fecund and resistant in environment because they are long-lived and sticky. Adult worms are large, host-specific, mouth surrounded by 3 fleshy lips; infect terrestrial hosts
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what is the basic life cycle of Ascaridida?
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infective 'egg' is ingested (with L2) - no free-living state > larva released from eggshell >hepatotracheal migration > mature to adult in small intestine
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how, basicly, is the host infected by Ascaridida?
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direct ingestion of egg or ingesting paratenic host; neonates infected by larvae transmitted through placenta or mammary glands
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what, basicly, is the result of a heavy infection?
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moderate enteritis, suboptimal growth, ascarid antigens result in strong allergens, hypersensitivity and inflammatory reactions
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where is Toxocara canis found?
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small intestine of dogs
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where is Toxocara cati found?
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small intestine of cats
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where is Baylisascaris procyonis found?
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small intestine of dogs and racoons
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where is Parascaris equorum found?
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small intestine of horse (especially under 2yrs)
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where is Ascaris suuni found?
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small intestine of pigs
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where is Heterakis gallinarum found?
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cecum of chicken, turkey, other birds
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what is the morphology of Toxocara canis?
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50-180mm. Cervical alae. Ascarid-type eggs with L2 larvae. Adult male has finger-like process at posterior end
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what is the morphology of Toxocara cati?
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30-120mm. Cervical alae prominent
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what is the morphology of Baylisascaris procyonis?
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100-220mm. No cervical alae. Eggs smaller and brown and granular
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what is the morphology of Parascaris equorum?
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adults up to 500mm
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what is the morphology of Ascaris suuni?
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150-400mm. 3 prominent lips but no cervical alae
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what is the morphology of Heterakis gallinarum?
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5-15mm. Esophagus has posterior bub. Lateral alae. Males have pre-anal sucker
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what is the life cycle of Toxocara canis in adults?
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(1) ingests infective L2 eggs > hatch in stomach > penetrate small intestine wall > portal veing > liver > caudal vena cava > heart > pulmonary artery > Somatic Migration to encyst as arrested larvae in various tissues or Tracheal migration via lungs > coughed/swallowed, mature to adult in small intestine (2) ingest paratenic host with encysted larvae in tissues > larvae reactivate in dog's stomach > mature into adult worms in small intestine
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what is the life cycle of Toxocara canis in neonates/immunocompromised?
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(1) ingests infective eggs or (2) ingests paratenic host > mostly tracheal migration > mature to adult in small intestine (3) transmission from mother to pup; arrested larvae in somatic tissues of dam are reactivated in late pregnancy > migrate via transuterine > transmammary
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what is the life cycle of Toxocara cati?
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no transuterine transmission (1) direct ingestion of infective eggs > tracheal or somatic migration common (2) transmammary > larvae in queen's tissues reactivated in late preganacy; larvae mature into adults in small intestine of kitten (3) ingestion of infected paratenic host
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what is the life cycle of Baylisascaris procyonis?
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(1) direct ingestion of eggs or (2) ingestion of infected paratenic host > tracheal migration. Dogs ingest eggs or get eggs on coat for humans to ingest later
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what is the life cycle of Parascaris equorum?
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ingest infective egg (L2) > eggs hatch in small intestine > hepatotracheal migration > coughed and swallowed > return to small intestine 2-4wks after initial infection
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what is the life cycle of Ascaris suuni?
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infection by ingestion of infective egg > larvae hatch in intestine, burrow out > hepatotracheal migration > coughed and swallowed > return to small intestine 7-8d post-infection
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what is the life cycle of Heterakis gallinarum?
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ingest infective eggs or paratenic earthworm
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what is the pathogenesis of Toxocara canis?
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young puppies have gastroenteritis with inflammation, hypersensitivity
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what are the clinical signs of Toxocara canis?
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abdominal pain, pot belly, poor coat condition, fetid mucoid diarrhea (bacteria from small intestine), respiratory signs are rare, adult worms vomited or shed in feces
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how do we diagnose Toxocara canis?
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adult worms in vomit or feces, but fecals are negative unless > 3-5 weeks
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how is Toxocara canis involved in zoonosis?
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visceral and ocular larva migrans via ingestion of infective egg; ocular through granulomatous reaction to larvae in eye
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what is the pathogenesis of Toxocara cati?
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less severe gastroenteritis (than T. canis)
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what are the clinical signs of Toxocara cati?
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less severe than T. canis, potbelly, poor coat, diarrhea
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how is Toxocara cati involved in zoonosis?
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visceral larva migrans
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what is the pathogenesis of Baylisascaris procyonis?
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greater risk of lethal visceral larva migrans and neuro than Toxacara
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what are the clinical signs of Baylisascaris procyonis?
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neuro symptoms from larvae migrating in CNS (aberrant host)
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what is the pathogenesis of Parascaris equorum?
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young horses get respiratory and intestinal, lung congestion via allergic reactions to migrating larvae; catarrhal enteritis, obstruction, performation, hypoproteinemia, colic candidate
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what are the clinical signs of Parascaris equorum?
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foals with diarrhea or fetid feces, potbelly, rough coat, respiratory problems
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what is the pathogenesis of Ascaris suuni?
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severe lesions in the lungs of piglets from repeated migration/inflammation and focal fibrosis (milk spots) in the liver and hypertrophy of tunica muscularis in small intestine resulting in bad absorption
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what are the clinical signs of Ascaris suuni?
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pulmonary disease, coughing (thumps of rapid, shallow, audible expriatory effort), larvae in sputum, diarrhea
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what is the pathogenesis of Heterakis gallinarum?
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minimal pathology in chickens, eggs and larvae are carriers of protozoa Histomonas meleagridis with results in transmission. Causes blackhead disease in turkeys: invade gut wall > inflammation > necrosis of cecum & liver, non-pathogenic in chickens
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what is the prepatent period of Toxocara canis?
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~3-5 weeks (5wks if infected by egg ingestion, ~3wk if infected prenatally), eggs appear only after patency; eggs take 4 wks to become infective in environment
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what is the prepatent period of Toxocara cati?
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~8wks if tracheal migration, shorter if transmammary
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what is the prepatent period of Parascaris equorum?
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~80d. Eggs require 10-14d to become infective. Females very fecund
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what is the prepatent period of Ascaris suuni?
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60d
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what is the prepatent period of Heterakis gallinarum?
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30d
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what is the treatment for Toxocara canis?
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various drugs against adults/larvae in lumen; not effective against migrating/arrested stages. Manage/treat pregnant dogs to reduce prenatal infection; give fenbendazole daily @ 50mg/kg starting at 40th day of gestation and continueing 2 weeks after whelping. treat all puppies with fenbendazole or pyrantel @ 2-3 weeks and repeat q2-3wks until 2 mo old
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what is the treatment for Toxocara cati?
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treatment can be started at 6-8wks (since no transuterine); fenbantel or praziquantel. Most common GI parasite of kittens
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what is the treatment for Baylisascaris procyonis?
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piperazine causes expulstion of larvae and adults. In dogs common anthelmentics are effect. Prevent exposreu to racoon feces
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what is the treatment for Parascaris equorum?
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sanitize environment, clean teats/udder of broodmares (eggs resistant), treat foal @ 2 mo with q2mo until 1 year old. Heavy infections past 4-6mo; do NOT use potent drug/dose because it can cause impaction or anaphylaxis from dead worms) so need to use mineral oil to lubricate dead worms
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what is the treatment for Ascaris suuni?
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eggs are numerous (200,000+/day.) treat sows coming off dirt 2 wks prior to farrowing, wash thoroughly before entering farrowing area. Fembendazole, levamisole + ivermectin to kill adult worms; only pyrantel tarrtrate kills newly hatched larvae which is given daily as a feed additive. not a problem in confinement units, only in dirt.
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what is the treatment for Heterakis gallinarum?
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deworm and clean environment. Don't mix turkeys with chickens or house on same area; infective stages can remain in environment for years in earthworm
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