The Food and Drug Administration banned the sale of turtles with shells less than 4 inches long in 1975 when it found kids couldn't resist kissing the tiny pets, sometimes contaminating themselves with the salmonella commonly found on turtles.
Turtle-related illnesses dropped sharply after the ban, but U.S. the Centers for Disease Control and Prevention said cases have been recorded in 30 states, The Washington Post reported Thursday.
A busy illegal trade keeps churning out the small pets, officials said, often raised on turtle farms and sold at flea markets, on the Web or in pet stores.
"We've really seen a big influx of these turtles for sale," Mike Lathroum, a senior officer with the Maryland Natural Resources Police, said. "I don't know why. We've not been able to determine the source."
People selling the turtles are often transients, doing business online or out of their cars.
If they get caught in one venue, officials said, they set up shop in another.
"We've not been successful at putting anyone in jail," Lathroum said. "A lot of times these people are from out of state, so getting them back here for court has been difficult. We write the ticket, and they go on their way."