The U.S. Centers for Disease Control and Prevention is calling a parasite that infects domesticated cats a “major neglected parasitic infection” which also has infected 1 in 5 Americans.

Kansas City veterinarian Dr. Brian Lucas says the parasite that infects cats and causes toxoplasmosis comes from mice. When cats go to use the litter box to pass stool, it passes on some of the spores from the parasite that people can come in contact with when they scoop out the litter.

Lucas says outdoor cats are more likely to turn up positive for the disease than indoor cats because they’re rodent seekers and the symptoms are almost non-existent. “Their means of eating are to catch prey and eat it, so their likelihood of being exposed is a lot higher,” he says. “However, even in my own house this week, we had a mouse and we have cats so if my cats were to have eaten that mouse they could have gotten exposed to it.”

Lucas says any warm-blooded mammal have the potential of carrying the infection. “So it can be in the meats that we eat that we buy at the grocery stores,” he says. “So, there are other ways that people could potentially come into contact with it.” The CDC lists the disease as one of the leading causes of human death that is attributed to food-borne illnesses in the United States.

The disease can also cause serious illness and even death to people with a low immune system such as newborns, chemotherapy patients, and AIDS patients.

AUDIO: Mary Farucci reports. (1:03)