(CNN) From January 2017 through February 2018, puppies sold at six pet store companies led to infections in 118 people in 18 states, the US Centers for Disease Control and Prevention reported Thursday.

The cause of illness: Campylobacter, common bacteria that can cause diarrhea, abdominal pain and fever, according to the CDC outbreak report published as part of its Morbidity and Mortality Weekly Report

No deaths occurred, though 26 people were hospitalized. Samples of the bacteria from patients showed resistance to all antibiotics commonly used to treat Campylobacter infections, including macrolides and quinolones, according to the CDC.

Most patients will recover from a Campylobacter infection within five days without treatment, though drinking extra fluids is recommended. In rare cases, an infection can lead to complications, including paralysis and even death. People with weakened immune systems, such as infants, the elderly and those with cancer or other severe illnesses, are most at risk of serious infection.

Sanitation and handling

The investigation began in August 2017, when the Florida Department of Health notified the CDC of six Campylobacter infections linked to a national pet store chain based in Ohio. Information from an examination of data prompted a multistate investigation to identify the source of outbreak and to prevent additional illness.

The CDC identified 118 people, including 29 store employees, who became ill between January 5, 2016, and February 4, 2018. Patients ranged in age from younger than 1 year old to 85, and most (63%) were female. States reporting illness were Connecticut, Florida, Georgia, Illinois, Kansas, Massachusetts, Maryland, Michigan, Missouri, New Hampshire, New York, Ohio, Oklahoma, Pennsylvania, Tennessee, Utah, Wisconsin and Wyoming.

Of the patients interviewed by the CDC, the overwhelming majority -- 99% -- reported direct contact with a dog, and 95% said the dog they'd touched was a pet store puppy. The health agency noted that most infections with campylobacteriosis stem from eating raw or undercooked poultry, unpasteurized dairy products, contaminated water and produce. And although infection usually does not spread from person to person, having sex with an infected person or changing an infected person's diapers can increase the risk.

Though the CDC report does not name pet stores involved in the outbreak, Petland, a national pet store chain, was implicated in the original CDC outbreak notifications.

"As a result of the inquiry, the CDC had no new recommendations for Petland other than to continue our established practice of in-store hand sanitization and education," the chain's director of public affairs, Elizabeth Kunzelman, wrote in an email.

Store records reviewed during the outbreak investigation revealed that 142 of the 149 investigated puppies had received one or more courses of antibiotics, according to the CDC.

Common-sense care

"At Petland all decisions relating to the use of antibiotics is determined by each of our store's independent, licensed, consulting veterinarians who are responsible for examining each of our puppies and determining any medical treatment," Kunzelman said. "We expect veterinarians to practice appropriate discretion with antibiotics on puppies, just as we would expect the same from pediatricians with babies."

Mike Bober, president and CEO of the Pet Industry Joint Advisory Council, which works directly with the CDC to develop educational programs for pet owners as well as industry and governmental organizations, said, "outbreaks of this kind certainly point to a need to make sure that everyone involved in the handling of animals is well-trained and follows important hygiene and handling practices that place an emphasis on preventing and taking steps to avoid disease transmission."

Because animals are living creatures, disease will arise on occasion, he said. "It's not something we can just sanitize out of existence."

"We do think it is responsible care and common-sense care that is the best approach here," Bober said. Wash your hands thoroughly and exercise care and caution when cleaning up after animals, since disease can be transmitted through fecal matter.

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The CDC also advises pet owners contact their veterinarians if they see signs of illness in a puppy or dog.

"Pet ownership is a tremendously positive thing in people's lives," Bober said. "More than two-thirds of Americans have pets, and the health benefits of the human animal bond far outweighs the risks that come with these naturally occurring organisms."