Since 1998, Consumer Reports has been testing broiler chickens in the U.S. for contamination and illness. In their latest test, announced in a report released this week, the consumer group found that two-thirds of whole birds purchased in U.S. grocery stores tested positive for Salmonella and/or Campylobacter, the leading bacterial causes of food-borne disease which infect approximately 3.4 million Americans each year. An additional 25,500 are hospitalized and 500 die from infection, according to the report. “Consumers still can't let down their guard,” says the report. “They must cook chicken to at least 165º F and prevent raw chicken or its juices from touching any other food.” The report found Campylobacter in 62 percent of chickens and Salmonella in 14 percent. Of the big brands, Perdue had the best score; Tyson, the worst.