An investigation into an E. coli outbreak that has hospitalized nine people is in its early stages, officials said.

Public Health — Dayton & Montgomery County officials are asking anyone who got sick after attending a July 3 customer appreciation picnic at Neff’s Lawn Care in Germantown to call 937-225-4460 to report their illness.

At least 36 people are sick after eating food at the annual customer appreciation picnic and Public Health officials have confirmed that five of the people taken ill are infected with E. coli 0157, said Bill Wharton, a spokesman for the health department.

E. coli 0157 is one of six strains of E. coli bacteria known to produce a toxin that can be fatal.

Wharton said that, to his knowledge, none of the people hospitalized are in life-threatening condition.

Health department staff are investigating the outbreak to see if they can determine the source of the infection, he said, and interviewing the people who got sick.

Investigators will look at how food for the carry-in picnic was prepared and stored. “We’ll go through the whole process,” Wharton said.

They’re also trying to test leftovers from the carry-in picnic, though it’s likely any leftovers have either been eaten or thrown out by now, Wharton said.

An estimated 200 to 300 people attended the event, Wharton said, but the number might be higher.

Symptoms of E. coli infection include stomach cramps and bloody diarrhea. If someone attended the picnic and ate contaminated food, they could still develop symptoms through today, Wharton said.

E. coli can spread through contaminated food, but it can also be passed from person to person, so it’s important that anyone who became ill after attending the event to wash their hands frequently to avoid infecting others in their household, Wharton said.

Most E. coli cases reported in Ohio occur during the summer, said Dr. Mary DiOrio, state epidemiologist for the Ohio Department of Health.

“When people are getting together and having outdoor gatherings this time of year, it’s a good time to remind them about good food safety practices,” she said.

Though E. coli contamination is most often associated with beef, the bacteria are found in produce, including vegetable sprouts, lettuce and cantaloupe, DiOrio said. Cooking and storing food at the proper temperature can help prevent foodborne illness.

More than 50 people were sickened in several states by E. coli 0157 found in romaine lettuce in March. The Centers for Disease Control and Prevention are investigating an outbreak of another strain of toxic E. coli that has sickened 15 people in six states since May.

A third strain of E. coli has been linked to clover sprouts at a national sandwich shop chain. More than 25 people were sickened in 11 states between December and March.

Between 5 and 10 percent of people who are infected with a toxic strain of E. coli develop a condition called hemolytic uremic syndrome, which can lead to kidney failure.

Reported cases of E. coli illnesses decreased about 44 percent from 1996 to 2010 in the U.S., according to the CDC.

Contact this reporter at (937) 225-7457 or peggy.o’farrell@coxinc.com.