The Center for Disease Control and Prevention (CDC) has confirmed that an outbreak of Campylobacter has infected 55 people in 12 states. Originally, all of the cases were linked to puppies sold at Petland in various states, however new information suggests that the people sickened in a few instances did not contract the illness from a Petland dog.

Thirteen people have been hospitalized because of the outbreak that began last month. Although the CDC explained that the infection is rather common, this strain is resistant to antibiotics, leading to a serious condition in some sufferers.

The infection is spread by contact with dog feces and symptoms include diarrhea, abdominal pain and cramping. Dr. Brian Lamb, from West Penn Medical Associates explained to reporters that some people never develop symptoms at all and heal from the infection naturally.

He also warned that lack of hygiene is the most common form of contraction. “If you don’t wash your hands afterwards, innocently touching your mouth or touching something that comes in contact with your mouth, you’re able to get it,” he said.

The CDC began an investigation last month when 39 cases of the illness were reported. By using DNA of the bacteria, experts were able to trace the infection to Petland puppies being sold over the last few months.

“We know that Campylobacter is common in dogs, that’s not new to us,” CDC veterinarian Dr. Mark Laughlin said. “But an outbreak of human illnesses due to contact with dogs is quite unique.”

He explained that 14 of the confirmed cases were Petland employees in five different states. Thirty-five others recently purchased a puppy from the retailer or visited the store, or a person who’d purchased a dog from it.

However, cases in Utah, Wyoming, New Hampshire and Maryland seem to suggest that the strain isn’t limited to the Petland pets. In a statement released by the company, it read, “more than 98% of people obtain their puppies from other sources, including shelters, rescues, friends, online and through local advertising. Petland is therefore pleased that the CDC is expanding its investigation.”

The chain is “redoubling” its efforts regarding proper hand sanitation too. The company said that it will reinforce “proper hand sanitation before and after playing with any of our puppies.” They added that the chain will continue to follow “strict sanitation procedures and protocols put in place by consulting veterinarians.”

The problem with this strain is that it can’t be combatted by antibiotics. The symptoms can be very severe in young children and the elderly, and lead to serious complications.

Brenda Douglas of Kansas City purchased one of the infected dogs from Petland in April. Veterinarians prescribed erythromycin for her infected pet, but she couldn’t believe it when the CDC listed that medication as one of the ones that were ineffective.

She had been treating her puppy for diarrhea for months before he was finally diagnosed correctly. Petland has paid for her medical bills, but she also requested and received a $3,500 refund for the animal.

Douglas said she wasn’t qualified to care for the dog she bought, especially considering that that poor puppy could have lasting digestive disorders. Douglas was fed up and callously stated, “I’m washing my hands of the whole thing.” She added, “It’s a mess. It’s unfortunate that it happened.”

She also said that Petland should be testing dogs for the disease before they are sold to customers.

Experts urge people to wash their hands after cleaning up after their pet or being in contact with an infected dog. Laughlin recommended that people “wash your hands thoroughly with soap and running water for 20 seconds any time you come into contact with animals. Especially when you are cleaning up animal poop or you come into contact with their food or their environments.”

If anyone suspects that they or their dog has Campylobacter, it’s advisable to seek a professional diagnosis immediately. The outbreak shows no signs of stopping.