Some people view their backyard chickens as pets — but they shouldn't snuggle or kiss them.

That advice comes from the U.S. Centers for Disease Control and Prevention, which is cautioning the public about a multistate salmonella outbreak related to live poultry.

Although the CDC has put out similar warnings in recent years, officials say the number of illnesses and salmonella outbreaks linked to live poultry is rising amid changes in the farming industry and as more people keep birds in their backyards.

"Since the 1990s, not only have we seen an increase in outbreaks, what we think is driving that is an increase in the trend and interest in owning backyard poultry," said Dr. Megin Nichols, a public health veterinarian at the CDC. "People are very interested in understanding more of where their food comes from."

Backyard chicken owners counter that the hobby is a safe, fun and educational way to provide food for their families.

They also say the CDC's safety guidelines are just basic common sense.

"You should do what your mom told you to do back when you were a little kid," said Laura Mikulski, who has three chickens in her backyard in Ferndale, Mich. "You should wash your hands, maintain sanitary conditions, and anything that could have touched something that touched poo, you don't put it in your mouth."

Salmonella bacteria live in human and animal digestive tracts and are shed through feces. The bacteria causes fever, severe diarrhea and abdominal cramps.

Most people recover from an infection in a few days without treatment. In rare cases, complications can lead to death.

Nichols said changes in farming industry practices are part of the reason salmonella outbreaks linked to live poultry are on the rise.

Individuals and feed stores are able to purchase chicks online through large mail-order hatcheries, she said. Chicks are often housed and shipped in large numbers, stressful conditions that can lead them to shed salmonella in higher numbers.

Some feed stores keep chicks in large bins that are accessible to the public.

"The way these chicks are produced and then sold has changed significantly, which is, I think, why we now see these large multistate outbreaks that spread across the country rather than small, local outbreaks," Nichols said.

She said the CDC began to more thoroughly investigate outbreaks in 2009. That's also when the agency began picking up on large, multistate outbreaks.

Officials often see an association with illnesses and people who recently purchased their birds.

"These aren't necessarily the birds that have been in the backyards for years and years," Nichols said. "These multistate outbreaks are often birds that just came into the home, that are stressed and they're shedding salmonella.

"There is also the cuteness factor, which means some people bring them into their house, cuddle them, kiss them, and by doing that give themselves salmonella."

The CDC urges people to wash their hands after handling chickens and not to allow them in their homes. Those who are younger than 5 or older than 65 or have weakened immune systems should not handle live poultry.

People should not drink or eat in the area where the birds are kept, the CDC says. And kissing live poultry is a definite no-no.

"We want people to be aware that there are great benefits from interacting with animals through raising poultry," Nichols said. "You have to just take simple measures to keep yourself and your family safe."