A total of 132 people in 38 states have become ill, according to the latest information from a Centers for Disease Control and Prevention investigation. Of the total, 38 were hospitalized.
The U.S. Food and Drug Administration also is investigating the outbreak and, earlier this week, recalled all food products containing powdered kratom from Triangle Pharmanaturals Las Vegas.
In Whatcom County, a woman in her 40s and a man in his 20s were sickened.
Neither was hospitalized.
Symptoms of salmonella illness include diarrhea, fever and abdominal cramps.
Kratom is a plant consumed throughout the world for its stimulant effects and as an opioid substitute. Its users also tout kratom as a natural painkiller and an herbal supplement that helps curb addiction.
Kratom is brewed into a tea, chewed, smoked or swallowed in capsules.
It is also known as thang, kakuam, thom, ketum and biak, according to the Washington State Department of Health, which is warning people against consuming kratom because it could be contaminated with salmonella.