The Lone Star tick, common to the southeastern U.S., is responsible for inducing meat allergies in some people, scientists say. CDC Public Health Image Library hide caption

itoggle caption CDC Public Health Image Library

Last year, Tom Mather caught 15,000 deer ticks in the woods of southern Rhode Island. "People really need to become tick literate," the University of Rhode Island researcher says. Brian Mullen for NPR hide caption

itoggle caption Brian Mullen for NPR

As white-tailed deer have returned to New England in the past century, they've brought with them tick-borne parasites that cause human diseases. marcinplaza /iStockphoto.com hide caption

itoggle caption marcinplaza /iStockphoto.com

Deer ticks like this one can spread a parasite that causes babesiosis. And infected people can spread it through blood donations. Jim Gathany/CDC hide caption

itoggle caption Jim Gathany/CDC