Romaine lettuce from California is safe to eat again nearly three months after an E. coli outbreak sickened 167 people across the country, the U.S. Centers for Disease Control and Prevention has announced.

An updated food safety report issued Wednesday by the Atlanta-based health agency says it’s "no longer advising that people avoid romaine lettuce from the Salinas Valley growing region in California."

The CDC and the Food and Drug Administration launched an investigation into the outbreak on November 22, and consumers in 27 states were warned to throw away or avoid romaine.

The largest number of illnesses reported was in Wisconsin, with at least 21 cases. Other cases were reported in Arizona, California, Colorado, Idaho, Illinois, Maryland, Michigan, Minnesota, Montana, New Jersey, New Mexico, Ohio, Pennsylvania, Virginia, and Washington.

After three months, health officials are still "doing everything possible to find the source or sources of contamination," said Frank Yiannas, FDA deputy commissioner for food policy and response.

"The investigation into how this contamination occurred is important, so romaine growers can implement measures that will prevent future contamination and illnesses," Yiannas said.

The majority of people interviewed after becoming ill reported they had recently consumed romaine lettuce.

No deaths were reported, the CDC said, but at least 85 people needed to be hospitalized, including 15 who developed acute kidney failure.

What is E. coli and how to avoid it

The bacterial strain known as E. coli O157:H7 was also identified in two outbreaks in 2017 and 2018. As in those cases, the latest outbreak may have also sickened people in Canada, reports said.

According to the Washington Post, the bulk of the romaine sold in the U.S. comes from two growing areas: the Salinas Valley of California (harvested in late spring, summer and fall) and the Yuma, Arizona, growing region that includes the Imperial and Coachella valleys of Southern California (winter and early spring).

Contaminated agricultural water is a prime suspect in these outbreaks.