March 9, 2016

CDC is collaborating with public health officials in multiple states and the U.S. Food and Drug Administration (FDA) to investigate a multistate outbreak of Salmonella Montevideo infections.

Public health investigators are using the PulseNet system to identify illnesses that may be part of this outbreak. PulseNet, coordinated by CDC, is the national subtyping network of public health and food regulatory agency laboratories. PulseNet performs DNA fingerprinting on Salmonella bacteria isolated from ill people by using techniques called pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). CDC PulseNet manages a national database of these DNA fingerprints to identify possible outbreaks.

A total of 11 people infected with the outbreak strain of Salmonella Montevideo have been reported from 9 states. A list of states and the number of cases in each can be found on the Case Count Map page.

Illnesses started on dates ranging from December 12, 2015 to February 9, 2016. Ill people range in age from 9 years to 69, with a median age of 31. Seventy-three percent of ill people are male. Among 9 ill people with available information, 2 reported being hospitalized, and no deaths have been reported.

This outbreak can be illustrated with a chart showing the number of people who became ill each day. This chart is called an epidemic curve or epi curve. Illnesses that occurred after February 11, 2016 might not yet be reported due to the time it takes between when a person becomes ill and when the illness is reported. This takes an average of 2 to 4 weeks. Please see the Timeline for Reporting Cases of Salmonella Infection for more details.

Investigation of the Outbreak

Collaborative investigative efforts of state, local, and federal public health and regulatory officials indicate that pistachios produced by Wonderful Pistachios of Lost Hills, California are a likely source of this outbreak.

In interviews, ill people answered questions about foods eaten and other exposures in the week before they became ill. Of the nine ill people who were interviewed, eight (89%) reported eating pistachios in the week before illness started. This proportion is significantly higher than results from a survey of healthy people in which 12% reported eating pistachios in the week before they were interviewed. When asked about the brand of pistachios eaten, five (63%) of eight ill people reported eating Wonderful brand pistachios.

Recent laboratory testing isolated the outbreak strain of Salmonella Montevideo from samples of raw pistachios collected from Paramount Farms, where Wonderful pistachios are grown.

Investigators are using WGS to get more information about the DNA fingerprint of Salmonella Montevideo causing illness. WGS showed that isolates from ill people are closely related genetically. In addition, WGS showed that isolates from raw pistachios supplied by Paramount Farms are also closely related genetically to isolates from ill people. This close genetic relationship provides additional evidence that ill people in this outbreak became ill from consuming pistachios produced by Wonderful Pistachios.

On March 9, 2016, Wonderful Pistachios voluntarily recalled a limited number of flavors and sizes of in-shell and shelled pistachios because they may be contaminated with Salmonella. The pistachios were sold under the brand names Wonderful, Paramount Farms, and Trader Joe's and were sold nationwide and in Canada, Mexico, and Peru.

This investigation is ongoing, and we will update the public when more information becomes available. CDC and state and local public health partners are continuing laboratory surveillance through PulseNet to identify additional ill people and to interview those people about foods they ate before they got sick.