Doctors say a severe stomach bug is making its rounds in at least eight states, infecting hundreds of people from Texas to Georgia.
The Centers for Disease Control and Prevention say more than 250 people have been infected with cyclospora.
Officials say 10 of those infected have been hospitalized.
Symptoms mirror the flu and include diarrhea, vomiting, headaches and body pain.
Experts say many patients felt those symptoms anywhere from weeks to a month.
Health officials are now trying to find where the mystery parasite may have originated.
Preliminary interviews with patients suggest fresh produce or contaminated water could be to blame.
Fortunately, the symptoms of cyclospora can be treated with antibiotics.
However, health experts say prevention is the best medicine and encourage everyone to wash all fruit and vegetables thoroughly before eating.