The tests traced the salmonella to closed containers of ground black pepper that would have been used to coat salami at Daniele Inc., a meat company in Burrillville, health department spokeswoman Annemarie Beardsworth said.
Daniele recalled more than 1 million pounds of salami last month after many of those who got sick reported they ate it.
Beardsworth said about half the people sickened didn't eat any salami.
"That maybe tells you that we're not done looking for a source of the outbreak yet," she said.
Daniele had two suppliers for the pepper, and the U.S. Department of Agriculture and the U.S. Food and Drug Administration are working to trace its origin and determine if it was distributed anywhere else, Beardsworth said.
"It was imported, and any pepper that is now coming into the country is going to be subject to additional testing," she said.
She said it was not yet known which country the pepper came from and whether it was sold directly to consumers or used in prepared foods.
The federal Centers for Disease Control reported this week that at least 203 people had been infected with the same strain of salmonella since July 1, and at least 40 were hospitalized.
It was reported in 42 states and the District of Columbia, including Alaska, Alabama, Arizona, California, Colorado, Connecticut, Delaware, Florida, Georgia, Iowa, Idaho, Illinois, Indiana, Kansas, Louisiana, Massachusetts, Maryland, Maine, Michigan, Minnesota, Missouri, North Carolina, North Dakota, Nebraska, New Hampshire, New Jersey, New Mexico, New York, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, West Virginia and Wyoming.