In the past month 311 patients have been added to the list of people with Salmonella infections related to contact with backyard poultry flocks. One person has died.

The total of confirmed infections now stands at 474, according to an update from the Centers for Disease Control and Prevention. The sick people live in 46 states, but the outbreak could involve more states and additional patients.

One-third of the confirmed patients are children younger than 5 yers old.

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Of patients with information available, 103 have been so sick they had to be admitted to hospitals. Illnesses started on dates ranging from Dec. 15, 2020, to June 4 this year.

"The true number of sick people in an outbreak is likely much higher than the number reported, and the outbreak may not be limited to the states with known illnesses," according to the CDC. "This is because many people recover without medical care and are not tested for Salmonella. In addition, recent illnesses may not yet be reported as it usually takes 3 to 4 weeks to determine if a sick person is part of an outbreak."

Testing in multiple states has shown the outbreak strains of Salmonella in backyard flocks, their enclosures, their bedding and their droppings.