Health investigators collaborating with the U.S. Centers for Disease Control and Prevention managed to link two separate Salmonella outbreaks to Mexican-grown mangoes through the oldest trick in an epidemiologist’s field book: patient interviews. Since August, the CDC worked with state and local health officials to investigate a number of Salmonella illnesses from a strain known as Braenderup that they soon publicly tied to mangoes grown by Agricola Daniella, which issued a full recall after its products were linked to the outbreak. Behind the scenes, local investigators in 3 states were also wrestling with another Salmonella outbreak, this one identified as Salmonella Worthington, a strain rarely found in the U.S. “The entire country will normally see maybe 15 Worthington cases in a year,” said Ian Williams, Ph.D., Chief of the CDC’s Outbreak Response and Prevention Branch. “Here, we had 16 in just a couple week period.” Between July 19 and September 12, those 16 Worthington cases cropped up in California, New Mexico and Washington state – 3 of the states hit by the larger Braenderup outbreak. Investigators started asking Worthington patients if they had eaten mangoes recently. Of the 9 interviewed, 8 said they had. One patient even tested positive for both Braenderup and Worthington. These multiple-strain outbreaks happen more often than many people realize, Williams said. He rattled off a list of similar outbreaks just from the last year: Cantaloupes with Salmonella Typhimurium and Salmonella Newport; raw tuna with Salmonella Bareilly and Nchanga; live poultry with Newport, Infantis and Lille. “Once you figure out the source of contamination, you’ll usually find other strains in the facility,” he said. Both outbreaks appear to have ended, but Agricola Daniella will remain on the FDA’s Import Alert list until testing proves their products are no longer contaminated.