As many colleagues whom I have Zoomed over the past years will know, I have always had a cat or two. When my kids were gestating, I remember both the GP and ante-natal staff giving strict instructions about avoiding litter trays because of the real and significant risk of toxoplasmosis, particularly to the unborn, immune-deficient foetus. So, when my stepdaughter recently acquired a kitten just weeks before dropping the next human in the family, I mentioned this and was surprised to hear that not one of her health professionals had mentioned the toxoplasma gondii parasite.

That got me thinking. I recall how toxoplasmosis scars due to chorioretinopathy use to be commonplace. Indeed, one of the patients in my qualifying exams had exactly that for me to diagnose. But over the past decades, they do seem to be less commonplace. While the current overall rate of toxoplasma infection in the UK is between 23-33%, the higher prevalence the further south and the highest in Greater London, it would appear that the old advice to pregnant women may have led to a decline in eye disease related to this infection.

A new study from the University of Bristol has concluded that, with increasing numbers of immunocompromised individuals in the population, ‘it is essential for health professionals to be aware of this important disease for both at-risk groups and the general public.’ Otherwise, we might start to see an increase in those familiar scars, or worse, active ocular inflammations again.

More worrying still, work in the US has shown that the protozoan, when hosted by rats, secretes a chemical that makes them more docile and more easily caught by cats. And newer stats still have established a link suggesting that humans carrying Toxoplasma are more likely to have depression and have car accidents. Maybe the infection has a more subtle impact.

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