North Carolina’s Department of Public Health laboratory confirmed on Thursday that the ongoing Salmonella Paratyphi B outbreak linked to Smiling Hara unpasteurized tempeh was caused by contaminated packages of spore culture used in the product’s fermentation process.

At least 63 people in four states have been sickened in this outbreak.

According to the Buncombe County Department of Health, the U.S. Food and Drug Administration is now tracing the origin of the culture to identify the source of the contamination. The FDA is also investigating the potential for other outbreaks linked to the culture.

Click here for more details about the outbreak.