It seems like the Midwest is a hotbed for medical mysteries these days.
Earlier this week, scientists traced a brand-new virus to ticks in Missouri. Now disease detectives are hot on the trail of another puzzling pathogen in the heartland.
A stomach bug has sickened at least 321 people across 14 states, the Centers for Disease Control and Prevention said Friday. The source of the outbreak is still unknown, though the parasite that's causing the outbreak, cyclospora, is usually found in food.
About 90 percent of the cases have been reported in Iowa, Texas and Nebraska. But the bug has also cropped up in the Southeast and New England.
Health officials say they still don't know how cyclospora is making it into people's meals.
Most of us aren't familiar with cyclospora, and that's a good thing. The parasite, which likes to hang out on fresh fruits and vegetables, causes a rather nasty bout of diarrhea that can last weeks.
"It's a tenacious critter," Dr. William Schaffner from Vanderbilt University told CBS News Thursday. "It can produce a prolonged, watery, very uncomfortable diarrhea."
And the bug doesn't stop there. "What's unique to this parasite is that it causes anorexia," or lack of appetite, says Ynes Ortega, from the University of Georgia's Center for Food Safety. "People lose a lot of weight, very fast."
"I have a friend who got the disease, and she said it was like being pregnant at first," Ortega told Shots. "Even the sight or smell of food makes you nauseous."
It's not the worst parasite out there, Ortega says. But it can put you in the hospital if you have a weakened immune system or another underlying illness.
At least 18 people have been hospitalized in the current outbreak.
The good news, Ortega says, is that the treatment for cyclospora is fast and effective. Sulfa drugs wipe out the infection quickly.
Cyclospora is relatively rare in the U.S. Most food poisonings here are caused by bacteria or viruses, like E. coli and norovirus. In contrast, Cyclospora is a protozoan, which typically hangs out in tropical and subtropical regions.
"We never realized that this parasite would come into the developed world," Ortega says. "Travelers would get it when they ate contaminated fruits and vegetables in communities with poor sanitation."
But since the U.S. started importing more of its produce, cyclospora has been tagging along. The first large outbreak occurred in 1996 and affected more than a thousand people. The CDC recorded about 4,100 cases between 1997 and 2008.
Often times, farm workers get the bug on their hands and then transfer it to produce. Or contaminated water is used to irrigate crops.
Previous outbreaks in the U.S. have been linked to basil, snow peas and raspberries. But any fresh fruit or vegetable can carry the bug. So until health officials pinpoint the source of the cyclospora, people should wash all their fruits and vegetables thoroughly.
"You can reduce the number of organisms on produce by washing it well," Ortega says. But to get rid of parasites completely, food has to be cooked. Sanitizers and bleach aren't going to work either.
People with watery diarrhea and other symptoms of cyclospora should contact their doctors, Ortega says. "This will help the CDC figure out just how wide spread the outbreak is and track down the source."