Parasites by type

Parasites by type

1. Arthropods

   • Insects
     • 3 body segments, hard exoskeleton, 
     • Flies
     • lice
       • heavy infestation called pediculosis
       • trichodectes chewing louse- IH for diplyidium tape worm
       • host specific permanant ectoparasite of mammals and birds
       • identification
         • dorsoventrally flattened 5mm long
         • 3 pairs of legs- wingless
         • blood sucking vs chewing lice
           • blood sucking- narrow head and LARGE claws
           • chewing lice broad head and small legs
       • LIFE CYCLE
         • Eggs->nymph->adult
           • simple metamorphoses 
           • eggs- cemented to the hiar
           • nymph sexually immature adulte emerge from egg
         • whole lifecycle occurs on animal and takes 2-3 weeks
       • PATHOGENESIS
         • chewing lice- rasping mouthparts feed on epithelial scales and feathers
         • sucking lice more pathogenic- pierce- can spread disease feed on blood cause anaemia on mammals only
         • unable to groom properly- self inflicted injury ad hair loss
       • EPIDEMIOLOGY
         • transmission- close contact- can't live off host for long
         • pediculosis seen over winter- thicker coat
         • pediculosis
           • cattle one chewing louse and several sucking lice
           • sheep one chewing- two sucking lice
           • pigs just have one louse type- sucking louse
           • horses have a chewing and a sucking louse
       • CONTROL
         • insectivides struggle to kill lice eggs- hard structures- give 2 treatemetns 2 weeks apart or give one treatment with 2 week residual activity to kill emerging nymphs
         • sucking lice more susceptible to systemic insectivides than chewing lice
     • Fleas
       • laterally flattened wingless insects
         • genus - ctenocephalides
           • TENO-KEF-ALI-DEES
         • cat flea most common can infect cats and dogs, dog flea host specific
       • identification
         • brown, small, large hind legs
         • pronotal and genal combs identify
           • none= pulex human flea
           • dog and cat flea have both
             • cat flea first and second genal comb the same length- sleeker head
               • dog head squarer and the first genal comb much shorter than second
       • life cycle
         • Eggs- not sticky drop off into environment
           • hatch to larvae which form cocoon- sticky attract environmental debris
             • 1-7 weeks grow to 5mm in two moults susceptible to dessication
             • pupa inside cocoon- pupate to adult
               • adult lifespan on host about 10 days
                 • lay egg 36-48 hrs post infection 
         • depends on pupal widow- egg to fully formed adult 3-4 WEEKS
         • juvenile development controlled by hormones- insect juvenile hormone drops after last moult. insect moulting hormone spikes at each one
           • you keep insect juvenile hormone synthetically above a certain level larvae will not develop further
       • epidemiology
         • 5% of flea population is on the animal
         • flea hotspots- accuulations of flea larvae and eggs in environment usually where the animal spends the most time
         • as the animal jumps down - eggs drop off onto the floor
       • pathogensis
         • restlessness- excess grooming, self injury
         • blood loss- possible disease spread
         • FAD flea allergic dermatitis- some animals develop to flea saliva normally following prolonged exposure. even a few bites lead to irritation
           • hair loss
           • crusty papules
           • generalised skin disease- milary dermatitis
       • diagnosis
         • demonstration of parasite- part hair and see flea- send to lab if ID required
         • comb adult over white paper/ blotting paper look for flea dirt
       • control
         • direct application of insectivides or insect growth regulators into the environment- treat all hotspots
         • hygine- vacuuming and wash teh pets bedding
   • Acarina
     • 2 body segments  no wings, antennae or compound eyes
     • mites
     • ticks

2. Helminths

3. protozoa

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