Publisher’s Platform: Basil Salmonella Outbreak is likely 38.6 times larger than reported

Only a small proportion of all Salmonella infections are diagnosed and reported to health departments. It is estimated that for every reported case, there are approximately 38.6 undiagnosed infections. The CDC estimates that 1.4 million cases, 15,000 hospitalizations, and 400 deaths are caused by Salmonella infections in the U.S. every year. Overall, the incidence of Salmonella in the United States has not significantly changed since 1996.^[1]

As of April 17, 2024, a total of 12 people infected with the outbreak strain of Salmonella have been reported from 7 states – Florida, Georgia, Minnesota, Missouri, New Jersey, Rhode Island and Wisconsin. Illnesses started on dates ranging from February 11, 2024, to April 2, 2024. Of 11 people with information available, 1 person has been hospitalized. No deaths have been reported.

Of 12 people interviewed, 10 (83%) reported shopping at Trader Joe’s. Seven sick people reported buying or likely buying organic basil in 2.5 oz clamshell-style containers from Trader Joe’s. Additionally, traceback data collected by FDA determined that Infinite Herbs, LLC, in Miami, Florida, was the supplier of the 2.5-oz packages of organic basil sold at Trader Joe’s stores.

While this investigation is ongoing, do not eat Infinite Herbs organic basil sold at Trader Joe’s stores in those 29 states and Washington DC. The basil was sold in 2.5 oz clamshell-style packages. Investigators are working to determine if additional products may be contaminated.

Salmonella is a bacterium that causes one of the most common enteric (intestinal) infections in the United States – salmonellosis. Salmonella are found in the intestinal tract of wild and domesticated animals and humans.^[2] The term Salmonella refers to a group or family of bacteria that variously cause illness in humans. Salmonella serotype typhimurium and Salmonella serotype enteritidis are the most common in the United States.^[3] Most Salmonella infections are caused by eating contaminated food, especially food from animal origins. One study found that 87% of all confirmed cases of Salmonella were foodborne, with 10 percent from person-to-person infection and 3% caused by pets.^[4]

Salmonella bacteria can be detected in stool. In cases of bacteremia or invasive illness, the bacteria can also be detected in the blood, urine, or on rare occasions in tissues. The test consists of growing the bacteria in culture. A fecal, blood or other sample is placed in nutrient broth or on agar and incubated for 2-3 days. After that time, a trained microbiologist can identify the bacteria, if present, and confirm its identity by looking at biochemical reactions. Treatment with antibiotics before collecting a specimen for testing can affect bacterial growth in culture, and lead to a negative test result even when Salmonella causes the infection.^[5]

Salmonella infections can have a broad range of illness, from no symptoms to severe illness. The most common clinical presentation is acute gastroenteritis. Symptoms include diarrhea, and abdominal cramps, often accompanied by fever of 100°F to 102°F (38°C to 39°C).^[6] Other symptoms may include bloody diarrhea, vomiting, headache and body aches. The incubation period, or the time from ingestion of the bacteria until the symptoms start, is generally 6 to 72 hours; however, there is evidence that in some situations the incubation can be longer than 10 days.^[7] People with salmonellosis usually recover without treatment within 3 to 7 days. Nonetheless, the bacteria will continue to be present in the intestinal tract and stool for weeks after recovery of symptoms—on average, 1 month in adults and longer in children.^[8]

In approximately 5% of non-typhoidal infections, patients develop bacteremia. In a small proportion of those cases, the bacteria can cause a focal infection, where it becomes localized in a tissue and causes an abscess, arthritis, endocarditis, or other severe illness. Infants, the elderly, and immune-compromised persons are at greater risk for bacteremia or invasive disease. Additionally, infection caused by antimicrobial-resistant non-typhoidal Salmonella serotypes appears to be more likely to cause bloodstream infections.^[9] Overall, approximately 20% of cases each year require hospitalization, 5% of cases have an invasive infection, and one-half of 1% die. Infections in infants and in people 65 years of age or older are much more likely to require hospitalization or result in death.

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^[1]           Voetsch, Andrew, et al., “FoodNet Estimate of the Burden of Illness Caused By Non-Typhoidal Salmonella Infections in the United States,” CLINICAL INFECTIOUS DISEASES, Vol. 15, No. 38, Supplement 3, pp. S127-34 (April 15, 2004) available online at http://cid.oxfordjournals.org/content/38/Supplement_3/S127.long

^[2]           Miller, S. and Pegues, D., “Salmonella Species, Including Salmonella Typhi,” in Mandell, Douglas, and Bennett’s PRINCIPLES AND PRACTICE OF INFECTIOUS DISEASES, Sixth Edition, Chap. 220, pp. 2636-650 (2005).

^[3]           Tauxe, R, “Emerging Foodborne Diseases: An Evolving Public Health Challenge.,” EMERGING INFECTIOUS DISEASES, Vol. 3, No. 4, pp. 425-34 (1997) at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2640074/pdf/9366593.pdf

^[4]           Buzby, Jean and Roberts, Tonya, “The Economics of Enteric Infections: Human Foodborne Disease Costs, GASTROENTEROLOGY, Vol. 136, No. 6, pp. 1851-62 (May 2009).

^[5]           Tauxe, R, “Emerging Foodborne Diseases: An Evolving Public Health Challenge.,” EMERGING INFECTIOUS DISEASES, Vol. 3, No. 4, pp. 425-34 (1997) at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2640074/pdf/9366593.pdf

^[6]           American Academy of Pediatrics, “Salmonella infections,” RED BOOK: 2006 Report of the Committee on Infectious Diseases, edited by L. K. Pickering, pp. 581–584 (27^th ed. 2006).

^[7]           Medus, C, et al., “Salmonella Outbreaks in Restaurants in Minnesota, 1995 through 2003—Evaluation of the Role of Infected Foodworkers,” JOURNAL OF FOOD PROTECTION, Vol. 69, No. 8, pp. 1870-78 (Aug. 2006), article abstract and paid-access to full-text available online at http://www.ncbi.nlm.nih.gov/pubmed/16924912

^[8]           Behravesh, C.B., et al., “Salmonellosis,” in CONTROL OF COMMUNICABLE DISEASES MANUAL, 19th Edition, published by American Public Health Association, pp. 535-540. (Heymann, D, editor 2008).

^[9]           Varma, Jay K., et al., “Antimicrobial-Resistant Non-typhoidal Salmonella is Associated with Excess Bloodstream Infections and Hospitalizations, JOURNAL OF INFECTIOUS DISEASES, Vol. 191, No. 4,  pp. 554-61 (Feb. 15, 2005) available online at http://jid.oxfordjournals.org/content/191/4/554.long