Just last week, health officials reported 48 new cases in Texas. That number has now grown to 353 cases in 14 other states.
The microscopic organism is made of just one cell. The cell can cause cyclosporiasis - an infection of the small intestine.
Health officials aren't sure how people are ingesting the parasite, but in the past it has been linked to eating contaminated produce.
For people in states across the country, it's caused a host of uncomfortable symptoms like watery diarrhea, vomiting, loss of appetite and fatigue. These symptoms can last a few days or a month or longer.
Despite the severe symptoms, CNN senior medical correspondent Elizabeth Cohen says the infection is not fatal.
"One thing that's important know is there are medicines that can help, so this is not something that we're seeing people die from," she said.
Treatment for this infection is usually a combination of antibiotics, fluids and as with many other illnesses, lots of rest.
According to the CDC, there is no vaccine against cyclosporiasis. They suggest that you thoroughly wash your fruits and vegetables several times to avoid infection.