Endoparasites

Endoparasites

1. Tapeworm-CESTODES

   • Segmented body
     • each segment contains 1 or 2 sets of male/female reprodcutive organs
   • STRONG LINK TO FLEAS
   • Dipylidium caninum

2. Live INTESTINES

   • egg develop in proglottids
     • Passed out in faeces
       • eggs dry out and are released in the environment
         • Eggs then ingested by primary/ intermediate host
         • Flea larvae eat eggs
           • Tapeworm larvae encyst in flea= becomre infective

3. Tapeworm-TAENIA

   • Found in DOGS/CATS
     • T. hydatigena
     • T. Ovis
     • T. pisiformis
     • T. serialis
     • T. taeniaformis
   • HAS INTERMEDIATE HOST
     • birds/squirrels/mice/sheep
     • when ingested- onchosphere moves into the blood/lymph/body cavity (inverts)
       • Onchosphere- embryo ID as the earliest differentiated stage of tapeworm
       • Once in predilection site, develops into either ADULT/LARVAL stage
         • ADULT- Echinococcus granulosus/Taenia Ovis/Taenia hydatigena/Taenia multceps
         • LARVAL-Hydatid cyst/Cysticerus Ovis/Cysticercus tenuicollis/Coenurus cerebralis
         • Once ingested by final host- scolex attaches to mucosa of gut lining
   • indirect life cycle with one intermediate host
   • Adult tapeworm found in small intestine of final host
   • Segments and eggs reach environment in faeces

4. Hydatid disease

   • Dogs infected by eating carcase/offal contaminated by cyst
   • Contamination of environment- canine faeces
   • Eggs survive in environment for up to 1 yr
     • Eggs ingested by intermediate host (usually sheep)
       • eggs hatch and larval form then migrate to predilection site then encysts
         • Cysts develop in liver/lungs- can affect brain
           • Continuation of life cycle when cyst eaten by host

5. Taenia ovis

   • Uncommon
   • Intermediate stage occurs in muscle- heart muscle of sheep

6. Taenai hydatigena- Cysticercus tenuicollis

   • Intermediate stage- found in abdomen of grazing animals

7. Roundworms (Nematodes)

   • No segments
   • Life cycle depends on age of pet
   • Majority live in intestines of animal- can live in R system or blood stream
   • Produce egss that pass out in faeces
     • eggs mature and are ingested by another animal
       • life cycle continues
   • Intermediate host can be involved
     • eats worm eggs and then eaten by another animal
   • Sometimes no clinical signs displayed
     • Signs can be failure to put on weight/foul breath/diarrhoea/constipation
       • Severe worm burden= anaemia/obstruction of bowel
   • Toxocara canis
     • Infected dog passes egg in faeces/milk/utero
       • Toxocare larva (inside egg) develops in environment
         • Dog ingests larva/egg
     • Dogs under 3 months old- after ingestion and hatching in small intestine larvae travel in blood via liver/lungs then return via trachea to intestine
     • Dogs over 3 months old- The hepatic tracheal migration occurs less often- larvae travel to tissue including: liver/lungs/brain/heart/skeletal muscle
       • Prenatal infection occurs in pregnant bitch
         • larvae mobilised 3 weeks priod to birth- migrate to lungs of foetus
     • Toxocare cati- larvae do not migrate to muscles, lie dormant in cysts
       • unborn kittens arent contaminates
         • As soon as kittens begin to feed risk of transmission through milk

8. TREATMENT

   • Febantal
     • In combo with pyrantel act against ascarids/hookworms/whipworms in DOGS
       • inhibit tubulin polymerisation
         • formation of microtubules prevented
         • glucose uptake affected- depletiion of cells ATP
         • Parasite dies due to exhaustion of energy reserves- 2-3 days later
     • Can combine with PYRANTEL embonate- same job as febantel
   • fenbendazole
     • Broad spectrum anthelmintic for CATS/DOGS with roundworm in GI or respiratory tract
       • Adults- infected with GI roundworms/tapeworm
         • T. canis/T cati/taenia spp
       • Weaned puppies/kittens
         • GI roundoworm and protozoa (puppies)
       • Pregnant bitches- reduce prenatal infection of T canis & transfer via milk
       • cats-lungworm
   • Praziquantel
     • Covers all impotant cestodes in DOGS
       • Immature and adult forms
     • rapidly absorbed through parasites surface resulting in paralysis
   • Milbemycin
     • Mites and adult/immature stages of nematodes & larvae of Dirofilaria immitis
     • interferes with invertebrate neurotransmission- paralysis and death
   • Moxidectin
     • DOGS and CATS- heartworm
     • Cats- GI nematodes- toxocara cati (adults worms)
       • Absorbed through skin- max conc 1-2 days post treatment
         • flaccid paralysis of parasites
     • Dogs
       • GI nematodes inc. toxocara canis
   • Nitrscanate
     • broad spectrum anthelmintic against common UK nematodesDOGS
   • Selamectin
     • roundworms- DOGS/Heartworm-CATS
       • paralysis of parasite