Four things to know:
1. The new numbers represent an additional 227 people and 20 states since investigators’ last update May 16. The CDC also identified four more strains of the bacteria.
2. Twenty-six percent of those infected have been hospitalized. There have been no reported deaths.
3. Evidence shows the outbreaks stem from contact with backyard poultry in several hatcheries. Interviews with patients found 77 percent had contact with chicks or ducklings.
4. The CDC identified one of the strains infecting people after examining backyard poultry samples in Ohio.
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