CDC is collaborating with public health officials in several states and the U.S. Food and Drug Administration (FDA) to investigate a multistate outbreak of Salmonella Paratyphi B variant L(+) tartrate(+) infections. The investigation has not conclusively identified the source of this outbreak, but most ill people interviewed reported eating sushi made with raw tuna in the week before becoming ill. The investigation is ongoing and has not identified a common brand or supplier of raw tuna linked to illnesses.

This outbreak is caused by Salmonella Paratyphi B variant L(+) tartrate(+) bacteria. The illness caused by this bacteria typically includes diarrhea, fever, and abdominal cramps 12-72 hours after being exposed. Salmonella Paratyphi B variant L(+) tartrate(+) does not cause paratyphoid fever, enteric fever, or typhoid fever.

Public health investigators are using the PulseNet system to identify illnesses that may be part of this outbreak. PulseNet is the national subtyping network of public health and food regulatory agency laboratories coordinated by CDC. DNA “fingerprinting” is performed on Salmonella bacteria isolated from ill people by using a technique called pulsed-field gel electrophoresis, or PFGE. PulseNet manages a national database of these DNA fingerprints to identify possible outbreaks. This PFGE pattern has never been seen before in the PulseNet database.

As of May 21, 2015, a total of 53 people infected with the outbreak strain of Salmonella Paratyphi B variant L(+) tartrate(+) have been reported from 9 states. Most of the ill people have been reported from the southwestern United States, or reported travel to this part of the country in the week before they became ill. The number of ill people reported from each state is as follows: Arizona (10), California (31), Illinois (1), Mississippi (1), New Mexico (6), South Dakota (1), Virginia (1), Washington (1), and Wisconsin (1).


Illness onset dates range from March 5, 2015 to May 3, 2015. Ill people range in age from younger than 1 to 83 with a median age of 31, and 47% are female. Among 46 people with available information, 10 (22%) have been hospitalized, and no deaths have been reported.