CDC, public health and regulatory officials in several states, and the FDA investigated a multistate outbreak of Salmonella infections. This outbreak was detected when a cluster of people infected with Salmonella I 4,,12:b:- was identified by CDC PulseNet. Epidemiologic and laboratory evidence indicated that kratom was the likely source of this multistate outbreak. Kratom, or Mitragyna speciose, is a plant that grows naturally in Thailand, Malaysia, Indonesia, and Papua New Guinea. It is consumed for its stimulant effects and as an opioid substitute.
State and local health officials interviewed ill people to ask about the foods they ate and other exposures before they became ill. Seventy-six (74%) of 103 people interviewed reported consuming kratom in pills, powder, or tea. Most people reported consuming the powder form of kratom. People who reported consuming kratom purchased it from retail locations in several states and from various online retailers.
During the investigation, health and regulatory officials in several states and the FDA collected various leftover and unopened kratom products from several retail locations and online retailers to test for Salmonella contamination. As additional strains of Salmonella were identified in kratom products, a search of the CDC PulseNet database identified ill people infected with some of these strains, including Salmonella Heidelberg, Salmonella Javiana, Salmonella Okatie, Salmonella Weltevreden, and Salmonella Thompson. These ill people were added to the outbreak investigation. Eighty-five different DNA fingerprints of Salmonella bacteria were identified in samples of kratom products. Several companies issued recalls of kratom products.
As of May 24, 2018, 199 people infected with the outbreak strains of Salmonella were reported from 41 states. Illnesses started on dates ranging from January 11, 2017 to May 8, 2018. Ill people ranged in age from less than 1 to 75 years, with a median age of 38. Among ill people, 52% were male. Of 132 people with available information, 50 (38%) were hospitalized. No deaths were reported.