America’s Food Safety System Failed to Stop a Salmonella Epidemic. It’s Still Making People Sick.

In May 2018, a rare and virulent strain of salmonella caught the attention of America’s top disease detectives. In less than two months, the bacteria had sickened more than a dozen people, nearly all of them on the East Coast. Many said they’d eaten chicken, and federal food safety inspectors found the strain in chicken breasts, sausages and wings during routine sampling at poultry plants.

But what seemed like a straightforward outbreak soon took a mystifying turn. Cases surfaced as far away as Texas and Missouri. A 1-year-old boy from...