The Center for Disease Control has issued a warning about a particularly virulent strain of stomach bug that has crossed into 6 states, infected nearly 300 people, and put at least ten of those in the hospital.

The stomach bug–a Cyclospora infection thought to come from imported fruits–has proven hard to track because no common social events link any of the patients, and some people are thought to have contracted it in another state from where they live. The CDC is working with the FDA to try and investigate the root cause of the infection, which causes diarrhea, vomiting, and flu-like symptoms. Adding to the difficulties is the fact that Cyclospora requires a special test and is relatively rare, so it is rarely diagnosed correctly. Still, anyone experiencing similar symptoms should contact their doctor immediately.

“Because Cyclospora can cause a prolonged illness and the disease is treatable with sulfa drugs, we want people to know that they should contact their doctor if they experience a gastrointestinal illness with watery diarrhea that lasts more than two or three days,” said Dr. Henry Anderson, Wisconsin State Health Officer.

The infection can cause relapsing symptoms that last for weeks at a time, because it incubates. Health officials expect to see the number of cases grow in coming weeks.