A new study says the parasite found in cat feces that causes toxoplasmosis is more widespread than previously thought and more people may be at risk.
Pregnant women have long been warned to beware of emptying their cats' litter boxes because of the dangers of toxoplasmosis, but new research shows the risk may apply to a much larger portion of the population.
Dr. E. Fuller Torrey and Dr. Robert H. Yolken from Johns Hopkins University Medical Center have studied the parasite Toxoplasma gondii or T. gondii, which causes toxoplasmosis and is most commonly found in cat feces. In their report in the journal Trends in Parasitology, Torrey and Yolken estimate that U.S. cats release roughly 1.2 million metric tons of feces into the environment every year, making the dangers of T. gondii a "potential public health problem."
Cat feces called a 'vast' public health problem
Severe toxoplasmosis can cause damage to the brain, eyes and other organs. The risk of serious illness from toxoplasmosis has previously been thought to be an issue primarily for those with compromised immune systems and for pregnant women, because pregnancy lowers the body's immunity and the infection can be passed to the fetus. But this report raises the possibility that toxoplasmosis could impact a larger population.
Another much talked-about study by Czech scientist Jaroslav Flegr claimed T. gondii may also cause paranoia, schizophrenia and other disorders.
Flegr has said that the cat feces parasite "may be quietly tweaking the connections between our neurons, changing our response to frightening situations, our trust in others," according to The Atlantic. In the article, Flegr claimed "Toxoplasma might even kill as many people as malaria, or at least a million people a year."
"There are also suggestions that Toxoplasma gondii can affect memory and other cognitive function in people who are not otherwise ill," the Johns Hopkins scientists told CNN. They added that "In no way have we established Toxoplasma gondii as a cause of these disorders, but it has led us to rethink the possible risks of cat poop."
According to the Centers for Disease Control, more than 60 million people in the U.S. may be infected with the Toxoplasma parasite, but most will not experience any symptoms because their immune system will fight off illness, and rates of infection are actually declining. The primary modes of transmission are through consuming undercooked meat that has been contaminated with the parasite, drinking contaminated water or accidentally swallowing infected cat feces. This accidental "hand to mouth" transmission most commonly occurs after cleaning a litter box or being exposed to contaminated soil.
This problem generally involves outdoor cats; for this reason, the researchers advise gardeners to wear gloves and parents to be especially vigilant about covering sandboxes and other dirt play areas, especially since young children often put their hands in their mouths.
"Cats selectively relieve themselves in areas with loose soil or sand. In the studies we reviewed, we found very high concentrations of Toxoplasma gondii oocysts in these areas," Torrey and Yolken told CNN.
“It should give you pause before you put your child in a public sandbox,” Torrey told NBC News.
Cat ownership in the U.S. increased 50 percent between 1989 and 2006, according to the Johns Hopkins report, up to 82 million, not including an estimated 60 million feral cats. Meanwhile, a single Toxoplasma oocyst (the term for each individual parasite) can lead to infection; a troubling fact considering the researchers told CNN that "a single infected cat can deposit millions of oocysts, each of which may survive in moist soil for 18 months or longer."
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