On July 7, 1997, a company physician reported to the Alexandria Department of Health (ADOH) that most of the employees who attended a corporate luncheon on June 26 at the company’s branch in Fairfax, Virginia, had developed gastrointestinal illness.

On July 11, the health department was notified that a stool specimen from one of the employees who attended the luncheon was positive for Cyclospora oocysts. Many others tested positive. It was subsequently revealed in a July 19, 1997, Washington Post story citing local health department officials that basil and pesto from four Sutton Place Gourmet stores around Washington D.C. was the source of cyclospora for 126 people who attended at least 19 separate events where Sutton Place basil products were served, from small dinner parties and baby showers to corporate gatherings. Of the 126, 30 members of the National Symphony Orchestra became sick after they ate box lunches provided by Sutton Place at Wolf Trap Farm Park.

In May 2001, 17 people in British Columbia were sickened with cyclospora associated with basil from Thailand.

In 2005, 300 people in Florida were sickened with cyclospora from fresh basil.

My aunt was part of that outbreak.

Beginning with California strawberry growers wrongly fingered as the source of a 1996 cyclospora outbreak that sickened over 1,000 people across North America (the culprit was Guatemalan raspberries) through to several outbreaks on an Australian cruise ship that sickened at least 314 in 2010, cyclospora keeps popping up.

Today it was Iowa, where consumers are being urged to carefully wash their produce as public health officials hunt for the source of a parasite that has caused severe diarrhea in at least seven Iowans.

The cyclospora infections have been confirmed in five counties in the past two weeks, the Iowa Department of Public Health reported Wednesday. Only 10 such cases had been reported in the state in the previous 20 years.

Dr. Patricia Quinlisk, the department’s medical director said while many previous Iowa cases have involved people who picked up the parasite while traveling to other countries, that doesn’t appear to be the source of this outbreak. “It looks like they got it here,” Quinlisk said.

The epidemiologist said previous U.S. outbreaks have been traced to fresh produce, such as raspberries, basil, snow peas, and mesclun lettuce. She urged the public to carefully wash produce before consuming it.

Washing produce will do little. And good luck washing that pesto from food service.