Even if they look clean, backyard poultry can carry Salmonella germs. These germs can easily spread to anything in the areas where the poultry live and roam, the CDC said in its closing report.

It is possible to get sick from touching backyard poultry or anything in their environment. The germs can be spread from hand to mouth contact.

The incident report said 1,135 people were impacted by the outbreak. Of those, 273 were hospitalised. Two deaths were reported in Indiana and Virginia.

Illnesses started 15 December 2020 and continued until 10 October 2021.

The true number of sick people in these outbreaks was likely much higher than the number reported, said the final report, and these outbreaks may not have been limited to the states with known illnesses.

The Salmonella outbreaks involved 48 states, including the District of Columbia and Puerto Rico.

Of 293 people who reported contact with backyard poultry and provided more information, 212 (72%) reported that they bought backyard poultry this year. Purchase locations included feedstores, auctions, and directly from hatcheries.

Traceback of these purchases did not identify a single, common source of backyard poultry. A total of 264 separate purchases from more than 150 purchase locations of 70 different companies were reported. At least 17 hatcheries supplied backyard poultry to these purchase locations.

The investigation is now closed.