Premenstrual syndrome and toxoplasmosis

I would like to quickly put the record straight, as I see it, about the news media’s reporting of a link between premenstrual syndrome and toxoplasmosis. The Irish News are reporting on this today although the Mexican University study to which they refer, on this topic, was published online in December 2016. The Irish Times reporter has acted irresponsibly in writing: “A STUDY involving 151 women linked toxoplasma gondii – a parasite carried by cats – to severe pre-menstrual syndrome (PMS) symptoms”. This distorts the findings of the study. I explain why below.

Toxoplasma gondii
Toxoplasma gondii. My thanks to Wikipedia for the image.
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The way the news was reported may make some women anxious because it builds on an already, I would argue, distorted story that pregnant women should get rid of their cats because of the potential for being infected by toxoplasmosis from their cat’s faeces in litter trays. There is a fear of transmission of T. gondii oocysts from faeces to person (hard to achieve). And an infection can harm a baby in the womb. So there’s a real danger here but it is a very, very slight risk.

In any case, Mexican scientists at Juarez University of Durango state, Mexico tried to determine the association of T. gondii with symptoms and signs of premenstrual syndrome. Four hundred and eighty-nine women (489) between the ages of thirty and forty participated. The authors of the study state, “Our study for the first time reveals a potential association of T. gondii infection with clinical manifestations of premenstrual syndrome”.

So we have to remember that the study found a “potential association”. This is not a definite link and clearly further research is required. And the number of participants was quite low. In fact, The Daily Mail reports that 150 women participated (the Irish News says it is 151) so there’s possibly an error in reporting by these newspapers.

The Daily Mail says that 10 of the women participating in the study were found to be carrying this parasitic protozoan and therefore were infected by toxoplasmosis – a small number. I am surprised that the researchers found it significant. It probably isn’t. We should remind ourselves that it is quite a common infection and is nearly always asymptomatic (without symptoms). And we should also remind ourselves that the most common cause of infection is not from cat faeces but by contaminated meats and vegetables.

How are people infected with toxoplasma
How are people infected with toxoplasma. Screenshot.

The researchers themselves admit that the study was small and that the findings need to be verified by further work. The fear that I have is that it may lead to the abandonment of domestic cats which is why I am making sure that people who read about this fully understand the conclusions of the study and don’t jump to incorrect conclusions.

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