Suspected cases of a parasitic infection that causes severe digestive issues are estimated to have tripled in just days - as officials are still trying to track down the source.

The CDC has reported that 145 Americans in 17 states have contracted the cyclospora parasite from an unknown source and 20 have been hospitalized. 

However, state health officials in Michigan confirmed to a local news outlet that there are more than 300 cases of people sickened with the parasite in the state alone. In the CDC's latest update from July 1, no cases were reported in Michigan. 

Michigan state health officials first reported the state's cases earlier this week, but the outbreak appears to quickly be growing. 

No recent travel has been reported among any of the patients, leading officials to believe the source is food. 

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

The CDC 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. 

As of July 1, 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. 

In Michigan, state officials told the Detroit Free Press this week that the first case was identified on June 22 and in the eight following days, dozens of more cases were identified. 

More than a dozen Michigan residents have been hospitalized with the infection. The state typically sees about 50 cases per year. 

Just a few days later, officials confirmed to WXYZ Detroit that there were now more than 300 cases of cyclosporiasis reported in Michigan since June 22.

'Many of these are initial reports, and we cannot say for certain that they are all part of the same outbreak. The investigation continues,' the Michigan Department of Health and Human Services said. 

Daily Mail attempted to contact the MDHHS but its offices were closed in observance of the July 4 holiday. 

Lynn Sutfin, a spokesperson for the Michigan Department of Health and Human Services, previously said in a statement: 'MDHHS is working with local health department[s] in southeastern Michigan to investigate a sudden and large increase in cyclospora cases and identify a common exposure.

'The department is coordinating the multi-jurisdictional investigation, assisting in case interviews. At this time, the source or sources have not yet been identified.'

The state health department issued a health alert to medical providers about the outbreak and is working with the CDC on its investigation. 

Sutfin added: 'Individuals concerned about sudden gastrointestinal illness should contact a healthcare provider.

'Individuals experiencing diarrheal illness or vomiting are encouraged to hydrate, particularly during the high temperatures expected this week.'

If not treated, cyclosporiasis 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, according to the CDC's report, 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.