(USATODAY.com) - Puppies for sale by a national pet store chain have passed along infections to people in seven states, the Centers for Disease Control and Prevention reported Monday.

Petland puppies were linked to 39 cases of human Campylobacter infections, which causes bloody diarrhea, fever, stomach cramps, nausea and vomiting. Campylobacter is spread through contact with dog poop, but can't spread from person to person. Nine people have been hospitalized because of the outbreak.

Of those infected, 12 were Petland employees and 27 recently purchased or visited a Petland puppy, the CDC reports. Petland is working with health officials.

States affected include Florida, Kansas, Missouri, Ohio, Pennsylvania, Tennessee and Wisconsin.

The CDC advises pet owners to wash hands often, contact a veterinarian if a puppy appears sick or sluggish and don't let puppies lick faces.