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18 Cards in this Set
- Front
- Back
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Secondary Nematode Pathogens/Contributors
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Haemonchus sp
Trichostrongylus spp Bunostonum spp Oesophagostomum sp Chabertia sp Trichuris sp |
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Secondary Nematode Pathogens/Contributors of Sheep
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Nematodirus spp
Cooperia spp Strongyloides sp Bunostonum sp Oesophagostomum sp Chabertia sp Trichuris sp |
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Names, Appearance, Life Cycle and Pathogenicity of Large Strongyles of Horses
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Strongylus equinus, S. edentatus, S. vulgaris, Triodontophorus spp.
Gross appearance Stout worms, 1.5-5cm long Large buccal cavity Bursa visible Leaf crowns, teeth, dorsal gutter Life cycle: L3 from grass ingested penetrate intestinal mucosa then: S. Vulgaris migrates through mesentaeric artery PPP 6-7 months S. edantatus through liver hepatic portal circulation and peritoneum. PPP 11-12 months S. equinus swims to liver through peritoneal cavity then back to intestine PPP 9 months Triodontophorus molts from L3 L4 in wall of intestine Pathogenicity Plug feeders: ulcers, bleeding, anemia |
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Life Cycle and Pathogenicity of Small Strongyles of Horses
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Cyathostomes
Small worms < 1.5cm long Life cycle Ingest L3 larvae invade mucosa of LI Larvae may develop to L4 without interruption Or can arrest at EL3 stage L4 emerge into gut lumen and mature to adult worms PPP 8-12 weeks Pathogenicity Plug feeders (superficial mucosa) Cyathostomosis L3 local inflammatory response Type 1: Larval emergence through summer. Tens or hundreds of thousands Type 2: emergence of previously arrested larva Serious disease, wt loss, severe diarrhea |
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Secondary Pathogens
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Trichostrongylus axei
Cattle, sheep, pigs, horses Pathogenicity is similar to Ostertagia but does not enter gastric glands nodular lesions Habronema/Draschia spp Spiruroids occurring in stomach Draschia found in torpics Mild gastritis Indirect lifecycle – Musca spp Onchocerca spp Filarial nematode, Indirect LC, cullicoides (midge) is intermediate host Thelazia sp Same as cattle, conjunctivitis, Indirect LC flies (Musca) |
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Life Cycle of Trichinella spiralis
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Life cycle:
L1 liberated from cysts by host digestive enzymes invade intestinal mucosa females lay prelarvae 5 days later enter lymphatics enter bloodstream transported to muscles develop into encysted L1 2-3 weeks later in striated muscle |
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Zoonosis of Trichinella spiralis
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Humans can become infected by eating undercooked pork (or another infected mammal)
Outbreaks are becoming less frequent in US and Europe, may still be a problem in less developed countries 5 larvae ingested per gram of body weight is fatal Periorbital edema, myalgia, fever, gastroenteritis, pruruitis, dermatological lesions, eosinophillia (in 20%) Control: Treatment of mammals rarely performed Sub/non clinical Meat inspection (most important method) Detected via biopsy, enzymatic digestion methods, ELISA Infected carcasses are destroyed Roast meat evenly to at least 77°C internal temp Freezing -15°C for 20 days |
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Macracanthorhynchus sp
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Beetle intermediate host
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Spiruroids: Ascarops stongylina and Physocephalus sexalatus
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Stomach worms of pigs
Not very pathogenic (secondary pathogens) |
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Toxocara canis
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Most prevalent nematode of dogs.
Almost ALL!! Puppies harbor this worm Can cause serious disease in large numbers Can invade human tissues Impairment of vision, media attention Typical ascarid: fleshy adult worm, up to 18cm long and lives in small intestine of dog, fox, and other canidae. Egg is characteristic dark egg with a pitted surface Significance/clinical signs Pot-belly, diarrhea, vomiting, wt loss: young puppies Can cause intestinal obstruction Possible zoonosis |
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Zoonosis of Toxocara canis
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3 disease syndromes in humans
Visceral larval migrans (VLM) Eosinophilia, hepatomegaly, fever, asthma Ocular larval migrans (OLM) Unilateral partial impairment of vision More common Covert toxocarosis (-iasis) Non specific clinical signs associated with high Ab titre In most cases, Toxocara infections are not serious, and many people, especially adults infected by a small number of larvae (immature worms), may not notice any symptoms. The most severe cases are rare, but are more likely to occur in young children, who often play in dirt, or eat dirt (pica) contaminated by dog or cat stool. |
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Toxocara canis Lifecycle in Puppies
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Larvae migrate via hepatotracheal route small intestine become adult eggs passed in feces
PPP is about 4-5 weeks |
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Nematodes of Dogs
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Toxocara canis- ascarid- small intestine
Toxascaris leonina- ascarid- small intestine Uncinaria stenocephala- hookworm- small intestine Ancyclostoma caninum- hookworm- small intestine Trichuris vulpis- whipworm- cecum Filaroides (Oslerus) osleri- lungs Angiostrongylus vasorum- heart Dirofilaria immitis- heart |
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Nematodes of Cats
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Toxocara cati- ascarid- small intestine
Toxascaris leonina- ascarid- small intestine Aelurostrongylus abstrusus- lungs |
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Lifecycle and Epidemiology of Toxocara canis in Other Warm-blooded Adults
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Many animals can be paratenic (similar to intermediate) host
Larvae migrate liver via heart to lungs stay in blood stream and back to heart somatic tissues (liver, kidney, musculature) granulomatous reactions “waiting phase” Will be protected from antiparasitics and remain inactive until: Eaten: ie non-canid Or pregnancy: female canids Treated male canids are not very signficant |
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Epidemiology of Toxocara canis in Dogs
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Infection of dogs is by ingestion of the L2, which can occur in four ways
Ingestion of embryonated egg Prenatal infection Transmammary infection Ingestion of paratenic host Infection of a paratenic host can occur by: Ingestion of embryonated egg Ingestion of larvae in the tissues of another paratenic host Each female T. canis 250,000 egg/day Eggs are not infected until L2 Eggs can survive 4-5 years, accumulated in environment Ie: breeding kennels, city parks, etc |
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Lifecycle and Epidemiology of Toxocara canis in Other Warm-blooded Adults
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Many animals can be paratenic (similar to intermediate) host
Larvae migrate liver via heart to lungs stay in blood stream and back to heart somatic tissues (liver, kidney, musculature) granulomatous reactions “waiting phase” Will be protected from antiparasitics and remain inactive until: Eaten: ie non-canid Or pregnancy: female canids Treated male canids are not very signficant |
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Epidemiology of Toxocara canis in Dogs
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Infection of dogs is by ingestion of the L2, which can occur in four ways
Ingestion of embryonated egg Prenatal infection Transmammary infection Ingestion of paratenic host Infection of a paratenic host can occur by: Ingestion of embryonated egg Ingestion of larvae in the tissues of another paratenic host Each female T. canis 250,000 egg/day Eggs are not infected until L2 Eggs can survive 4-5 years, accumulated in environment Ie: breeding kennels, city parks, etc |
