February 20, 2018

CDC, public health and regulatory officials in several states, and the U.S. Food and Drug Administration (FDA) are investigating a multistate outbreak of Salmonella I 4,[5],12:b:- infections.

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 techniques called pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS). CDC PulseNet manages a national database of these DNA fingerprints to identify possible outbreaks. WGS gives a more detailed DNA fingerprint than PFGE.

As of February 16, 2018, 28 people infected with the outbreak strain of Salmonella I 4,[5],12:b:- have been reported from 20 states. A list of the states and the number of cases in each can be found on the Case Count Map page. WGS performed on isolates from ill people were closely relatedly genetically. This means that people in this outbreak are more likely to share a common source of infection.

Illnesses started on dates ranging from October 13, 2017 to January 30, 2018. Ill people range in age from 6 to 67 years, with a median age of 41. Sixteen people are male. Eleven hospitalizations have been reported. No deaths have been reported.

This outbreak can be illustrated with a chart showing the number of people who became ill each day. This chart is called an epidemic curve, or epi curve. Illnesses that occurred after January 23, 2018, might not yet be reported due to the time it takes between when a person becomes ill and when the illness is reported. This takes an average of 2 to 4 weeks. Please see the Timeline for Reporting Cases of Salmonella Infection for more details.

WGS analysis did not identify any predicted antimicrobial resistance in isolates from five ill people. Testing of outbreak isolates using standard antibiotic susceptibility testing methods is currently underway in CDC’s National Antimicrobial Resistance Monitoring System (NARMS) laboratory.

Investigation of the Outbreak

Epidemiologic evidence indicates that kratom is a likely source of this multistate outbreak. Kratom is a plant consumed for its stimulant effects and as an opioid substitute. Kratom is also known as Thang, Kakuam, Thom, Ketom, and Biak.

In interviews, ill people answered questions about the foods they ate and other exposures in the months before they became ill. Eight (73%) of 11 people interviewed reported consuming kratom in pills, powder, or tea. No common brands or suppliers of kratom have been identified at this time.

At this time, CDC recommends that people not consume kratom in any form. The investigation indicates that kratom products could be contaminated with Salmonella and could make people sick. CDC’s recommendation may change as more information becomes available. This investigation is ongoing and we will provide updates as needed.