GRAND RAPIDS, Mich. (WOOD) — E. coli cases are rising in West Michigan, and it’s unclear where they came from.

Some of the cases are landing kids in the hospital.

So far this month, the state health department has reported 98 cases in Kent, Ottawa and Oakland counties. That’s nearly five times more than over the same time period last year.

Kids are more susceptible to the illness. In Ottawa County, three children have been hospitalized with serious kidney complications from E. coli. A Spectrum Health spokesperson confirmed to News 8 that a number of kids are at Helen DeVos Children’s Hospital for the same kidney issues.

While E. coli cases usually rise during the summer, the health department is alarmed by the major increase in August.

“It is significantly higher,” said Jim Collins, the director of communicable disease for the Michigan Department of Health and Human Services. “That’s the signal that originally got us to look more closely at these cases.”

Collins said it’s likely many of the cases are related but just how many is unclear. He also said the kidney complications can “be very serious.”

Dr. Kira Sieplinga, a pediatric hospitalist at Helen DeVos Children’s Hospital, also said hospital officials are “definitely concerned” about the kidney complications.

“As a mom and also a physician, just be using caution with the foods that you’re serving your children right now until we’ve figured out the reason for the outbreak,” she said.

The strain of E. coli that can cause the kidney issues usually occurs three to seven days after the initial diarrhea symptom, Sieplinga said.

“Children less than 10 are more susceptible to that kidney disease,” she said. “We don’t fully understand why.”

Still, kidney complications from E. coli are rare, she said. General E. coli symptoms are abdominal pain, diarrhea, nausea, vomiting and sometimes a low-grade fever.

“Most infections are mild,” Sieplinga said. “The diarrhea will subside usually in about five to seven days. You can usually manage that at home.”

Sieplinga said parents should watch out for diarrhea with blood in it as well as dehydration. Signs of dehydration include decreased urine, energy and saliva, she said.

As a precaution, she also recommended washing your hands, cooking meats thoroughly, washing your fruits and vegetables and making sure you don’t cross-contaminate when preparing food.

“It’s not a situation where we’re just helpless,” Collins added. “There’s a lot of things we can do as individuals to help minimize the impact of these infections.”

It’s unclear where the E. coli outbreak came from. Health departments are racing to investigate how the rise of cases began.

“We’re continuing to look at every possible source,” Collins said. “It’s kind of a detective job. We have to interview all the people who are reported in our system and find out where they ate for the 10 days previous to their infection.”

Sieplinga said E. coli is spread through “oral contact or taking it into the mouth.”

“That’s usually through foods or water,” she said. “Lake swimming or pool swimming where there’s been an infectious contact.”

Health officials aren’t sure if these cases were a one-time exposure or if the illness is still out there, Collins said.

“It could be something that’s persisting in the environment,” he said. “We want to make sure if it’s a product on store shelves and restaurants, we want to make sure that product is removed as soon as we can.”