How dirty litter box could slow you down as you age

A common cat-borne parasite already linked to risk behavior and mental illness in humans may also contribute to exhaustion, loss of muscle mass and other signs of “frailty” in older adults, a study published Nov. 6 in the Journal of Gerontology: Medical Sciences.

The research, conducted by an international team of scientists including University of Colorado Boulder, University of Maryland School of Medicine and the University of A Coruña in Spain, is the latest investigation into how the tiny, single-celled organism Toxoplasma gondii (T. gondii) can have major consequences for human health.

“We often think of T. gondii infection as relatively asymptomatic, but this study highlights that for some people it can have significant health consequences down the road,” said co-author Christopher Lowry, professor in the Department of Integrative Physiology at CU Boulder.

About 11% to 15% of people in the U.S. have been infected with T. gondii, and the numbers are often much higher in older individuals. In some countries more than 65% are infected. Once infected, people can unknowingly harbor the parasite for life.

For the study, the team examined the blood of 601 Spanish and Portuguese adults over the age of 65, along with measures of a common geriatric syndrome known as ‘frailty’ – which includes unintentional weight loss, fatigue, loss of cognitive acuity and other indications of declining health. .

As many as 67% of the subjects were ‘seropositive’ and showed markers in their blood of a latent infection.

The researchers found no link between T. gondii infection and frailty, as they originally hypothesized. But they did find that among those infected, those with a higher ‘serointensity’, or higher concentration of antibodies against the parasite, were significantly more likely to be vulnerable.

Higher serointensity could reflect a more virulent or widespread infection, multiple infections, or recent reactivation of a latent infection, the authors said.

“This paper is important because it provides evidence for the first time of the existence of a link between frailty in older adults and the intensity of the response to T. gondii infection,” said co-author Blanca Laffon, professor of psychobiology at the University of California. the interdisciplinary center for chemistry and biology at the University of A Coruña.

How cats spread T. gondii

Wild and domestic cats are considered the definitive hosts of the parasite, while warm-blooded animals such as birds and rodents serve as secondary hosts: when cats eat infected animals, T. gondii takes up residence and multiplies in their intestines, releasing eggs in their feces are disposed of. .

People typically become infected by exposure to those eggs (via litter boxes, contaminated water, or dirty vegetables) or by eating undercooked pork, lamb, or other meat that is contaminated. Most people never know they are infected, with only about 10% initially becoming infected. short flu-like symptoms. But T. gondii tends to linger dormant for decades, shrouded in cysts in muscle and brain tissue (particularly the emotion processing area known as the amygdala) with some insidious consequences, mounting research suggests.