PARASITOLOGY

PARASITOLOGY

Female worms

in gut

Free-living

soil larvae

Infective larvae

penerate skin

Dormant L 3 larvae activated

during pregnancy

Puppies infected

in utero via placenta

Puppies acquire larvae

via milk

nAdult worms live in the gut of puppies and bitch; eggs pass out via faeces; eggs containing L 2

larvae are ingested by dogs (accidentally by man); in bitch and puppies larvae migrate from gut

to lungs and back to the gut.

n Embryonated eggs are swallowed and the larvae hatch into the gut lumen. Larvae (L 2 )

penetrate through the gut mucosa of the dog and then proceed to migrate to the

lungs; and then eventually back to the gut mucosa to remain dormant within the

tissues.

• Figure 4.4Strongyloides
  stercoralisis an intestinal
  nematode. Free-living soil
  larvae infect the host by
  penetrating through the
  skin. The larva migrates to
  the gut. The mature worm
  first develops a male
  gonad and after sperm
  production the female
  gonads form. There is self-
  fertilisation. The first stage
  larvae hatch out of the
  eggs in the gut lumen.
  Larvae pass out into the
  soil via the faeces. Single
  sex (homogonic) or male
  and female (heterogonic)
  free-living larvae develop
  in the soil.


• Figure 4.5 Toxocara
  canisis a parasitic
  nematode found mainly in
  domestic dogs. Dormant
  third stage larvae are
  activated during pregnancy
  and the puppies are
  infected in utero and/or
  via milk. The worms
  mature in the pups and
  the mother can become
  re-infected from eggs in
  the pups’ faeces.