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Why does my cat do that? The mystery of purring
by Darina Schweizer
What do raw meat and cat litter trays have in common? Both are potential sources of infection with the Toxoplasma gondii parasite.
There are a number of inconvenient things about being pregnant. One of those inconveniences, the Toxoplasma gondii parasite, however, offered me a silver lining during my own pregnancy: for a whole nine months, I didn’t have to clean out our cat’s litter tray. Allow me to explain why.
Toxoplasma gondii, a single-celled organism found all over the world, causes a zoonosis (a disease transmitted from animals to humans) known as toxoplasmosis. It’s a parasite with the ability to embed itself into our cells – the cells in our muscles and brain, to be precise. As spine-chilling as that sounds, most people who become infected at some point in their lives don’t suffer any consequences. Many of them don’t even realise that they’ve caught it. The pathogen can, however, be dangerous to people with compromised immune systems. Unborn children can also be at risk if their mother becomes infected with toxoplasmosis during pregnancy.
In Switzerland, the number of people with Toxoplasma gondii antibodies has been steadily decreasing since the 1980s, from over 50 per cent of the population at that time, to less than 30 per cent today. The figures in Germany are significantly higher, with an average of 50 per cent for adults. In the USA, however, only one in ten people on average have been infected with the pathogen in the past.
There are two main ways that a toxoplasmosis infection can occur:
In some cases, unborn babies become infected in the womb if their mother comes into contact with toxoplasmosis during pregnancy. However, if the mother is infected before falling pregnant, the embryo is protected by the mother’s antibodies.
Eighty to 90 per cent of all toxoplasmosis infections are symptom-free. However, even when symptoms do appear, their resemblance to flu means people infected with toxoplasmosis are often unaware of it.
Prenatal Toxoplasma infections, on the other hand, (that is, when a woman becomes infected during pregnancy and transmits the pathogens to her unborn child), can have more serious consequences. If the infection occurs during the first trimester of pregnancy, it can severely damage the embryo or cause miscarriage. If the infection occurs later in pregnancy, the effects are varied, ranging from retinitis, to calcification of the brain’s vascular structures, to other changes in the brain.
A T. gondii infection isn’t just dangerous to unborn children. People with compromised immune systems are also at risk of severe consequences, including encephalitis (inflammation of the brain).
The Robert Koch Institute has issued some advice to help prevent infection with the parasite:
If you want to find out more, you’ll find more information (in German) on the Swiss Federal Office of Public Health or Robert Koch Institute websites.
Header image: Sandyman/ShutterstockScience editor and biologist. I love animals and am fascinated by plants, their abilities and everything you can do with them. That's why my favourite place is always outside - somewhere in nature, preferably in my wild garden.