In each outbreak below, a dot represents a test for salmonella performed by the Food Saftey and Inspection Service. A blue dot (·) means no salmonella; a red dot (·) means inspectors found the bacteria.
The government allows some salmonella on poultry — different amounts depending on the product — and even though some samples tested positive for salmonella at these plants, those amounts were within limits allowed by government standards.
Routine FSIS sampling of whole chickens showed no positive tests for salmonella during the six months before this outbreak.
The aftermath: This outbreak began in March 2013 and officially ended in July 2014. During that time, seven strains of salmonella Heidelberg sickened 634 people in 29 states. Nearly 40 percent of the ill were hospitalized, twice the normal rate for salmonella. The chicken was ultimately traced to three California plants of Foster Farms, the largest poultry producer on the West Coast.
Routine sampling of ground turkey showed only eight positives for salmonella out of 61 samples, well within what was then the standard for ground turkey -- 49.9 percent positives.
The aftermath: This strain of salmonella Heidelberg found in ground turkey sickened 136 people and killed one between February and November 2011. Approximately 39 percent of those infected ended up in the hospital. In August 2011, the company recalled more than 36 million pounds of ground turkey. Since the outbreak, FSIS has proposed new standards that will reduce the allowable level of salmonella in ground turkey to 13.5 percent.
FSIS tested whole chickens for salmonella in late 2011 and found no signs of the bacteria, but in the six months leading up to the start of this outbreak in June 2012, the agency didn't perform any sampling, according to the USDA data.
The aftermath: This outbreak officially ended in May 2013, sickening 134 people in 13 states. More than 30 percent of those who fell ill were hospitalized. Some of the salmonella Heidelberg associated with the outbreak was resistant to one of the key antibiotics used to treat the bacteria. The outbreak was traced to two Foster Farms plants, one in Kelso, Wash. and another in Fresno, Calif. Inspectors had been testing whole chickens, but most of those sickened had eaten meat sold as parts -- breasts, thighs or wings.
Routine sampling of ground turkey came up with only two positives for salmonella out of 28 samples, well within what was then the standard for ground turkey -- 49.9 percent positives. Since the outbreak, FSIS has proposed new standards that will reduce the allowable level to 13.5 percent.
The aftermath: The outbreak of ground turkey burgers began in December 2010 and sickened 12 people with salmonella Hadar in 10 states. In April 2011, Jennie-O recalled 54,960 pounds of frozen raw turkey burger products.
Normal FSIS sampling showed no salmonella, but a special "exploratory sampling" program geared at mechanically separated chicken -- meat that is ground into a paste and used in lunch meats and fast food -- did find the bacteria in some tests.
At the time, however, there were no standards for the amount of salmonella allowed on those types of products, meaning Tyson wasn't breaking any rules by selling them. The agency has since proposed new salmonella standards for mechanically separated and ground poultry.
The aftermath: This outbreak began with nine people from a Tennessee correctional facility who were sickened by a strain of salmonella Heidelberg, starting in November 2013. Tyson Foods recalled approximately 33,840 pounds of the chicken in January 2014.