More than 100 people have been sickened by a parasite across more than a dozen states and officials are investigating to track down the source. 

The CDC reports 145 Americans in 17 states have contracted the cyclospora parasite from an unknown source and 20 have been hospitalized. No recent travel has been reported among the patients, leading officials to believe the source is food. 

The cyclospora parasite causes cyclosporiasis, an infection that leads to diarrhea, severe cramping, nausea and vomiting and fatigue. 

As of June 16, the CDC reports 145 cases in people aged five to 86. The illnesses range from May 1 to June 6. No deaths have been reported. 

The agency said: 'Local, state and federal (CDC, FDA) public health authorities are investigating several clusters of cases in more than one state. Investigations to identify potential sources are ongoing.'

It is possible there are more undiagnosed cases in other states as well, as not everyone who contracts the parasite gets tested or treated for it. 

Cyclosporiasis is acquired through eating or drinking food or beverages contaminated with the parasite, often from feces. Symptoms usually occur about a week after exposure. 

Human-to-human transmission is rare.  

If not treated, the illness could last for more than a month, with symptoms subsiding and reappearing multiple times. 

To prevent cyclosporiasis, the CDC recommends avoiding consuming food or water at risk of contamination with feces and following general food safety preparation guidelines. 

Treatment consists of a course of the antibiotic trimethoprim-sulfamethoxazole, which is sold as Bactrim, Septra or Cotrim. 

Most people with a healthy immune system will recover without any treatment. 

Cases of cyclosporiasis tend to rise between May and August and it is more common in people returning to the US from foreign travel. 

In the current outbreak, New York is experiencing the most cases, between 31 and 80. 

Texas and Illinois are experiencing the second-most cases, between 11 and 30. 

The remaining 14 states with cases are experiencing between one and ten cases in each. 

Previous outbreaks have been linked to bagged salad kits, cilantro, basil and other leafy green produce - though no source or suspected source has been identified in this outbreak.  

An additional 45 cases of cyclosporiasis have been reported in people who ate or drank food or water that made them sick while traveling outside of the US.

These patients range in age from 17 to 89 years old. 

Of the 45 patients, three have been hospitalized and no deaths have been reported. 

The CDC did not reveal where the patients had reported recent travel.