As the trend of backyard flock tending skyrocketed in recent years, so has deadly infections, the Associated Press reports.

Since 2015, the number of Salmonella infections from contact with backyard poultry has quadrupled across the nation. This year, nearly every state has been pecked by outbreak strains; only Alaska and Delaware can crow about dodging them. The Centers for Disease Control and Prevention has confirmed 1,120 cases. Nearly 250 of those involved hospitalization, and one person died.

But that is likely just scratching the surface of the real numbers, according to CDC veterinarian Megin Nichols. “For one Salmonella case we know of in an outbreak, there are up to 30 others that we don’t know about,” she told the AP.

Salmonella is an invader of the gastrointestinal tract and a common food-borne illness. Those infected can develop diarrhea, cramps, and fever. Young children, the elderly, or people with compromised immune systems can develop more serious illnesses, including blood and organ infections.

Chickens and other fowl can carry Salmonella in their guts with no symptoms and silently shed the germs in feces. The bacteria can get stuck to their feathers and kicked up into dust around a coop.

This is well known to seasoned farmers, and proper handling and precautions can prevent contamination and sickness, the CDC says. Anyone raising or handling live poultry should make sure to wash their hands afterward, for starters. Other measures, like leaving shoes worn in or near a coop outside and not hugging chickens also work to protect poultry keepers.

Backyard poultry can pick up Salmonella at any time, but many come from hatcheries already infected. The US Agriculture Department encourages hatcheries to test for Salmonella, but testing is not required and is done on a voluntary basis. The AP reports that many of the consumer birds come from just 20 or so feed and farm supply retailers. And those draw baby fowl from just about half a dozen large hatcheries across the country.

Consumers can try to get their birds from a hatchery that tests for Salmonella. But Nichols suggests flock owners to just always assume the birds are infected and to care for them responsibly. “We view this as a preventable public health problem and are really hoping we start to see some change,” she said.