Toxocariasis
is infestation with the juvenile (young)
forms of the common puppy worm Toxocara
canis or, rarely, the similar cat parasite
Toxocara cati. The condition is largely found
in children who come into contact with puppy
fur and soil contaminated with puppy or
cat faeces.
London parkland
has been shown to be widely contaminated
with Toxocara worm eggs deposited by dogs.
Soil samples taken from almost anywhere
within the parks are found to contain their
eggs.
Human infestation
with toxocara is more common than has been
supposed, since many cases are free of symptoms.
Symptoms
Many cases
do not have any symptoms. However,
those that do show the following signs in
the early stages:
- Fever
- Pale colour
- Loss of
appetite and weight
- Coughing
and wheezing
- Feeling
sleepy and uninterested
Causes
When the
eggs are swallowed, they hatch in the intestine.
The juvenile worms burrow through the wall
of the bowel into the bloodstream.
They are
then carried to every part of the body and
can remain alive in the tissues for many
weeks, where their movement produces tracks
of bleeding.
Eventually
they die. At the sites of death, small abscesses
and collections of fibrous tissue and new
blood vessels (granulomas) occur. In some
cases, live juveniles may remain walled
up for years, only to resume their movements
at a later date.
Treatment
The early
stages are often undiagnosed, so that no
specific treatment is given. But if the
condition is detected, the drug albendazole
is often given for one week.
If a person's
eye is affected, this can be a difficult
problem to treat and damage may be permanent.
Steroids
may be used to try to minimise the damage
from inflammation. A laser can be used to
kill the juvenile worm and to prevent its
migration to the more important central
area of the retina.
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Toxocariasis
