Three people in Minnesota have fallen ill with salmonella, part of a national outbreak that health authorities have linked to pet hedgehogs.

Officials have confirmed 20 cases in eight states since December 2011, the U.S. Centers for Disease Control and Prevention (CDC) said Friday.

Four people have been hospitalized and one has died in Washington state.

After an investigation, the center concluded that the strain came from contact with hedgehogs, which have become popular pets in some parts of the country.

Fourteen of 15 patients interviewed by the CDC reported contact with a hedgehog or its environment before getting sick.

While investigators haven't determined how common salmonella is in the small spiny mammal, they said the bacteria is common in a variety of small animals, including reptiles, amphibians and poultry.

"Animals can appear healthy and clean but still carry the pathogen salmonella," said Tara Anderson, a CDC epidemic intelligence officer.

The CDC said people who touch hedgehogs or their environments should take extra care to follow basic hygiene practices such as washing hands. Pet owners should avoid washing out terrariums or feed bowls in kitchen sinks to avoid contamination, according to Kirk Smith, supervisor of the foodborne diseases unit for the Minnesota Department of Health.

The three reported cases in Minnesota were salmonella typhimurium, the same strain found in the other seven states.

Of the three cases in Minnesota, the state Health Department confirmed direct contact with a hedgehog in one case, which the CDC used to isolate a strain of the bacteria. Smith said the department couldn't confirm contact with a hedgehog in the other two cases, but said they were "almost certainly related" to contact with the animal.

The current outbreak in Minnesota is modest compared to other salmonella cases, Smith said. "It's probably just a small part of a much bigger issue of getting salmonella from animals," he said.

Food-borne salmonella is more common, Smith said, but getting the bacteria from animals is more common than previously thought, he said.

The CDC said 45 percent of the recent cases involved children 10 or younger, and it urged adults to supervise children washing their hands.

Salmonella symptoms include diarrhea, fever and abdominal cramps 12 to 72 hours after infection, according to the CDC's website. Symptoms can last four to seven days, and those infected usually recover without treatment.

However, for those with weaker immune systems, such as infants or the elderly, a severe infection is more likely, according to the CDC.

Anderson said the CDC would be contacting breeders to try to determine the source.

Kevin Burbach is a University of Minnesota student reporter on assignment for the Star Tribune.