Should We Be Worried About Parasites from Cats?
You can never be slim or rich enough, said the late duchess of Windsor; but can you ever be too worried about your health? Epidemiologists are always finding new things for us to fret about, new threats in the environment for us to avoid if we can or bite our nails over if we can’t. It is, as the French say, their métier.
One of the latest scares is over a parasite called Toxoplasma gondii, a protozoon parasite that until recently was thought to be harmless for everyone except for the fetuses of pregnant women and people with much reduced immunity, for example patients with AIDS or Hodgkin’s lymphoma. This parasite is, if not quite ubiquitous, very common, so if it really is harmful there might be a lot to worry about. This is no time for complacency: where health scares are concerned, it never is.
The definitive host of the Toxoplasma parasite is the domestic cat, but it can be passed on to other animals, especially those that provide us with our animal protein (although cattle are relatively resistant to infection), and it thus enters the human food chain.
A recent editorial in The Lancet contains a sentence that could become a locus classicus of epidemiological neurosis. Having pointed out "the widely held view that Toxoplasma gondii contamination in food and human infection in general should not cause public concern," it goes on to say, "However, infections could have as yet poorly understood adverse consequences." That no definite adverse consequences have not yet been discovered does not necessarily mean that they are not there; there is an old medical dictum that says that absence of evidence is not evidence of absence. Relaxation, about anything then, can never be justified.