|
Toxocariasis is sometimes confused with toxoplasmosis, a
disease caused by Toxoplasma gondii, a protozoan harboured
by cats. It has been known for some years that Toxocara
cati, the feline variant of Toxocara canis can
transmit Toxoplasma gondii. It has now been established
(Lin 1998; Silva et al 1997) that dogs also
harbour Toxoplasma gondii.
Whilst cats remain the most important reservoir of toxoplasmosis,
the dog must also be regarded as a vector. Some dogs eat cat
faeces and this may be one route of transmission. The disease
can be fatal to humans and is particularly dangerous to the
unborn child, causing gross deformities. The official stance
on toxoplasmosis can be gathered from the oblique response
given to Baroness Robson's Parliamentary question (House
of Lords 1994).
It may be deduced from the response that there is no prospect
that information which might identify the sources of infection
will be gathered nationally and that to date there seem to
be no government warnings of the dangers of diseases acquired
from cats or dogs. It is possible to misinterpret the results
of otherwise sound investigations into dog-related diseases
because of unrecognised factors in the environment. For example,
blood samples from a group of Luton school children were found
to contain high levels of antibodies (Josephs et
al 1981) despite the fact that some of the children
had no dog at home. It might have been concluded from this
that dogs were not implicated. However, subsequent analysis
of soil samples from a local park revealed dog faeces to be
the source of the infection, so dogs were implicated. Analogously,
allergens from dogs or cats encountered outside the home can
cause asthma, and this may partly explain the high incidence
of this ailment.
|
