Science On Tap

Whenever a woman becomes pregnant, she receives unusual advice: don’t change cat litter. While cat litter may seem relatively innocuous (well, except for the gross factor), it poses a real danger to a developing fetus. Hiding in cat poop are the eggs of a parasite, Toxoplasma gondii.

This parasite is usually not a problem for healthy humans; our immune systems can fight it off and we rarely feel major effects. However, for a fetus with an undeveloped immune system, Toxoplasma gondii can have devastating effects such as brain damage, blindness, or even death. The child may even be born appearing fine but may develop blindness or learning disabilities in adolescence.  Because of this, pregnant women who might have been exposed to this parasite, through cat litter, contaminated soil, or contaminated food, often get a blood test for Toxoplasma gondii.  If they are found to have Toxoplasmosis, infection by Toxoplasma gondii, they are prescribed anti-parasite medications which usually save their children from the infection.

Unfortunately, blood tests for Toxoplasmosis aren’t ubiquitous; rather, they are ordered on an “as needed” basis. In a study in the US, only 8% of women who gave birth to children with Toxoplasmosis were tested during pregnancy. 

But, why aren’t these women being tested?

These tests can be expensive and are deemed “unnecessary.” After all, every year there are only 400 to 4,000 cases of toxoplasmosis in babies in the United States. (Unfortunately, no recent studies have come out to make that number more precise). Regardless, this number is small compared to the 4 million babies born every year in the US. But, I would certainly argue that those babies that were infected with Toxoplasmosis deserve efforts to reduce infection.

Last year, a study came out in PLOS Neglected Tropical Diseases, that showed the effectiveness of a new finger-prick test for Toxoplasma gondii. Using a sample size of 205 pregnant women, this new finger-prick test was found to be 100% sensitive to toxoplasmosis and 100% specific for this parasite. Furthermore, this test only costs $4 to $5.

If this finger-prick test becomes widespread, Toxoplasmosis testing may become much more common, preventing congenital Toxoplasmosis.