Beginning in February of this year, numerous kratom-containing products have been linked to a large outbreak of salmonellosis. The FDA has now concluded its months-long investigation after identifying extremely high rates of salmonella contamination in kratom products collected and tested. This has led to multiple recalls, including the agency’s first mandatory recall order to one supplier. In addition to the known addictive properties and serious harms linked to kratom use, the evidence from this investigation points to another significant risk with the use of kratom: salmonella.
Today, we are providing a brief overview of the scientific analysis and how we arrived at these conclusions.
In February, the U.S. Centers for Disease Control and Prevention (CDC) PulseNet identified an outbreak of illnesses due to salmonella (“Salmonella I 4,,12:b:-”) that initially involved 24 people. The illnesses were linked to each other through molecular fingerprinting of the Salmonella I 4,,12:b:- bacteria using a laboratory technique called pulsed-field gel electrophoresis. Interviews conducted by state and local health departments in coordination with the CDC found that a high proportion of the ill people reported recent consumption of kratom, either as capsules, powders or herbal remedies.
In some instances, the affected patients still had the kratom they consumed before becoming ill available for testing. In other instances, patients provided information on the source and brand of the kratom that they had purchased either over the internet or from a commercial establishment. Investigators then collected samples of the named products for further testing.
The collected kratom samples were tested for the presence of salmonella either in state public health laboratories or by FDA laboratories. If salmonella was found, the FDA worked with marketers to voluntarily recall the kratom product to prevent additional people from becoming ill.
In most of these instances, the marketers were cooperative and a series of voluntary recalls ensued. In one instance, the marketer was uncooperative and failed to conduct a voluntary recall to prevent further harm. In this case, the FDA issued a mandatory recall order to protect public health. This was the first time that the FDA has needed to issue a mandatory recall order to protect Americans from contaminated food products since the agency obtained this authority in 2011 in the Food Safety Modernization Act.
As more kratom samples were tested, additional illnesses caused by salmonella serotypes other than I 4,,12:b:- were identified. These testing results were provided to the CDC, which compared the molecular fingerprint data from kratom samples to the CDC’s PulseNet database of salmonella fingerprint data of the salmonella strains collected from sick people in the United States. In several instances, matches were found between the salmonella strains in the kratom samples and strains that had been found in samples from sick people. Interviews of these people, who in some instances had been ill months earlier, found that they too had consumed kratom. This showed that the problem of kratom being contaminated with salmonella was more widespread than originally identified.
As of the end of May 2018, a total of 199 cases of salmonellosis in 41 states have been linked to kratom consumption; 38 percent of those illnesses led to hospitalizations. Fortunately, there have been no known deaths related to these illnesses. In addition to Salmonella I 4,,12:b:-, illnesses have been linked to Salmonella Heidelberg, Salmonella Javiana, Salmonella Okatie, Salmonella Thompson and Salmonella Weltevreden. A total of 81 samples of kratom were collected and tested as a direct result of the outbreak investigation, and 42 (52 percent) were found to be contaminated with salmonella. This means that users of these products had essentially a one in two chance of being exposed to this pathogen.
Although these samples were not randomly collected but instead were tested because they were either consumed by, or mentioned by, ill persons, the more than 50 percent contamination rate is stunningly high. It represents a level rarely seen in outbreak investigations of this nature. It shows that a high proportion of kratom being shipped into the United States may be contaminated with salmonella. Throughout the year, the FDA announced additional kratom recalls due to salmonella contamination of products from multiple different companies and brands, showing that this is a persistent problem.
Most kratom that flows into the United States is sourced from southeast Asia, particularly rural regions of Indonesia and Thailand. In these locations, the plant is being grown, harvested and processed in problematic conditions that readily create the circumstance for widespread contamination with foodborne pathogens. Although some of the kratom is further processed once in the United States into capsules, powders or herbal remedies, based on our findings, these procedures do not appear to be eliminating microbial contamination. This places unsuspecting customers at risk of salmonellosis.
Kratom is not legally marketed in the United States as a drug or dietary supplement. Kratom is an opioid, is addictive and has been linked to severe health consequences and deaths among users. Despite these risks, we know that kratom has grown in popularity in recent years due to unsubstantiated claims about its purported benefits.
It appears the salmonella problem with kratom uncovered earlier this year has probably been occurring for some time and is ongoing. We have closed our outbreak investigation, concluding that anyone consuming kratom may be placing themselves at a significant risk of being exposed to salmonella.
As we have previously stated, there are no proven medical uses for kratom and the FDA strongly discourages the public from consuming kratom. The subsequent findings of this investigation only strengthen that public health recommendation. Kratom is an inherently addictive product that can cause harm, which is reason enough not to consume it. Now, in addition to those risks, we can conclude that there may be a high proportion of kratom and kratom-containing products contaminated with salmonella. It’s another firm reminder of why people should avoid kratom.
The FDA, an agency within the U.S. Department of Health and Human Services, protects the public health by assuring the safety, effectiveness, and security of human and veterinary drugs, vaccines and other biological products for human use, and medical devices. The agency also is responsible for the safety and security of our nation’s food supply, cosmetics, dietary supplements, products that give off electronic radiation, and for regulating tobacco products.