By: Heather Williams

Another nationwide outbreak has arisen. This time, tuna is implicated in several cases of Salmonella.

A recall has been issued for Relish Foods tuna products for Salmonella infection at the same time an outbreak is being investigated involving Salmonella.  This leaves investigators asking questions.  Madison Riethman, an applied epidemiology fellow at Clark County Public Health in Washington state has been involved in the outbreak investigation since September 27th.  Investigators are working to connect the dots to identify the source of the outbreak, though information is leaning towards the already recalled Relish Foods tuna products.  Both local and federal agencies have been involved in this outbreak.

Salmonella Outbreak Investigation

Salmonella has infected 30 people across seven states.  The subtype paratyphi has been indicated in this outbreak linking confirmed cases with tuna consumption.  Local and federal agencies are working to get to the bottom of this outbreak to indicate a source and help prevent future associated cases.

The investigation began when five reports of Salmonella infection were reported in one day, August 29, 2017.  According to Riethman, the department typically sees three to eight cases of Salmonella in a month, indicating an investigation was warranted.  “The fact that we got five in one day was a big red flag,” she said.

At the time, interviews didn’t indicate anything common between those sickened.  According to the Riethman, they didn’t eat at the same places, attend the same event, and at face value these five cases didn’t seem connected. When the lab report was released ten days later on September 8, 2017 it was revealed that all five people tested positive for the same Salmonella strain.  Salmonella paratyphi.  “They’re all the same genetic pattern, which tells us they’re all probably from the same place,” Riethman said.  On this same day, another 12 cases were identified as being infected with the same Salmonella paratyphi strain.  This brought the case count to 17 with a common strain.

As more data from interviews came trickling in, a link was coming together.  At this time 14 of the sick individuals had been interviewed.  11 of those interviewed indicated that they had eaten sushi prior to becoming sick.  The Oregon Department of Agriculture began investigating a seafood company on September 11, 2017 as the case count had increased to 22.  By September 15, 2017 25 had become sick across four states including Hawaii, New Jersey, Oregon, and Washington.  Cases from California, Florida, and Texas were added to the list soon after with 30 cases confirmed by September 27, 2017.  At this time no new cases have been reported.  “We haven’t identified any new cases, so we hope we’ve at least stopped any ongoing exposures,” Riethman said.  At this time there is no information on age range, gender, or any other demographic information.  Investigators continue to research to determine a link between those who are sick.

While the case count is currently 30, many cases go unreported by normally healthy individuals whose symptoms don’t require medical attention.  Many times those with mild symptoms do not report their case to the local health department or submit a sample for confirmation.  The multiplier for Salmonella outbreaks is 38, indicating that the number of infected people could potentially be more than 1,000.  This is why it is very important for those who have experienced symptoms consistent with Salmonella infection to come forward.  The more information investigators have, the easier it is to determine a common source.

Tuna Recall

Initially, a tuna company that initiated a recall after lab tests showed that some samples tested positive for Salmonella was a subject of interest according to Riethman.  In fact, the Oregon Agricultural Department requested restaurants to hold use of the fish from that company until more information could be gathered.  Additional testing proved that the particular strain found in the positive tuna samples did not match the strain that was isolated from outbreak victims.

Later, the tuna company Relish Foods of Culver City, California issued a recall of frozen, Newport brand tuna loins.  This occurred on October 13, 2017 and potential Salmonella contamination was implicated.  The recall indicated that an FDA test returned positive for Salmonella, but the outbreak was not mentioned anywhere in the report.  Later the next week the recall notice was expanded to include tuna steaks and different sizes of tuna loins not included in the original recall.  Still the outbreak was not officially linked.

Officially, Relish Foods, Inc. of Culver City, California issued a voluntary recall of tuna products on October 13, 2017.  The initial recall indicated affected products as frozen Newport brand 5 to 8 pound tuna loins.  This recall was initiated due to FDA sampling identifying Salmonella present in the sample.  Since that time, the recall has been expanded to include 3 to 5 pound tuna loins, 6 ounce tuna steaks, and 4 ounce tuna steaks.  The product was distributed in Arizona, California, Idaho, Montana, Nevada, Oregon, Texas, Utah, Washington, and Wyoming between 6/17/2017 and 10/13/2017 through food service operations, retail stores, and restaurants.

Notice the overlap between recalled tuna and states affected by the outbreak.  At this time no serotype has been indicated for the positive Salmonella results, so a firm link cannot be made between the Salmonella recall and the Salmonella paratyphi outbreak.   Additionally, the recall is issued for the same time period as those who have been linked in the outbreak.

Salmonella Infection

Symptoms of Salmonella infection generally appear between 12 and 72 hours after infection.  Symptoms generally include abdominal cramps, diarrhea, and fever and usually lasts for 4 to 7 days.  Most healthy individuals recover without treatment, though cases with severe diarrhea may require hospitalization to treat severe dehydration.  Some patients may have Salmonella infection that leaves the intestinal tract to enter other body sites.  Without prompt treatment, this could become fatal.  The very young, the very old, and those with a compromised immune system are more likely to experience a severe illness associated with Salmonella infection.

While rare, a small number of those sickened with Salmonella infection can develop a disease called reactive arthritis, which can last for months or even years, possibly leading to chronic arthritis.  Often those who develop reactive arthritis also experience irritation of the eyes and painful urination.

 

Sources:

http://www.spokesman.com/stories/2017/oct/26/clark-county-among-first-in-us-to-link-salmonella-/

https://www.fda.gov/Safety/Recalls/ucm582049.htm

https://www.cdc.gov/salmonella/general/index.html

https://www.cdc.gov/salmonella/reportspubs/salmonella-atlas/serotyping-importance.html