A salmonella outbreak related to exposure to wild songbirds and birdhouses left 19 people ill in eight states, eight of whom were hospitalized.
The Centers for Disease Control and Prevention said they were studying salmonella infections in California, Kentucky, Mississippi, New Hampshire, Oklahoma, Oregon, Tennessee, and Washington state in people aged 2 months to 89 years.
Six cases have been reported in Washington and five in Oregon. No deaths were reported.
Public health officials across the country surveyed 13 of the infected and asked them about animals they had come into contact with a week before they became ill, the CDC said. Nine said they owned a bird feeder and two reported that they came into contact with a sick or dead bird. Ten people said they had pets that had access to or contact with wild birds, the agency said.
To avoid further cases, the CDC recommends cleaning birdhouses and bird baths once a week or when dirty. People should avoid bare-handed feeding of wild birds and wash their hands with soap and water after touching bird food or bathing, or handling a bird.
In California, where three human cases have been reported, the state Department of Fish and Wildlife warned of an outbreak in February and reported that it had been “swamped” by calls from Californians finding sick or dead finches at birdhouses.
Andrea Jones, director of bird protection at Audubon California, said the state had determined that most of the birds affected by the outbreak were pine teats, a species of finch that spends the winter in California. That year, numerous pine cisks gathered in California, which allowed the outbreak to spread among the birds.
“It can happen any year, but this has been a particularly bad year,” said Ms. Jones. “Pine Siskins aren’t very good at social distancing.”
Sick birds often look weak, sluggish, or appear to have difficulty breathing, Ms. Jones said. She added that most birds die within 24 hours of being infected with salmonella.
Many pine teats are now leaving California for Canada, Ms. Jones said, adding that she hoped the outbreak could end soon.
Salmonella bacteria can spread from birds to pets and humans. According to the CDC, people can experience diarrhea, fever, and stomach cramps six hours to six days after being infected. Children, adults aged 65 and over, and people with compromised immune systems sometimes have worse cases of salmonella, although most people will recover without treatment in one case a week or less.
With many people recovering quickly and not being tested for salmonella, it was likely that the actual number of cases caused by the outbreak was much higher than the number of reported cases, according to the CDC.
About 1.35 million cases of salmonella are reported in the US each year. Of these, about 26,500 will have to be hospitalized and 420 will die, according to the CDC