(NEW YORK) -- Reported cases of cyclosporiasis, an intestinal illness caused by a parasite, have surpassed 2,600 in Michigan, the state's health department said on Monday.

Cases jumped by more than 1,000 since Friday for a total of 2,642 reported since June 22, according to the Michigan Department of Health and Human Services (MDHHS). At least 44 people have been hospitalized. Michigan typically sees about 50 cases per year.

Most cases have been reported in southeastern Michigan, including Wayne County, where Detroit is located, according to MDHHS.

MDHHS data shows that most cases have been among adults, with the 30-39-year-old group making up the highest share, followed by the 40-49-year-old group and then the 60-69-year-old group.

The outbreak was first identified on June 29, when the Monroe County Health Department announced it was investigating a cluster of cases.

Michigan health officials previously told ABC News that the working hypothesis is that the outbreak is linked to food contamination, but so far, no produce, grower or supplier has been identified.

Earlier this month, MDHHS sent out recommendations to restaurants and other commercial kitchens in southeast Michigan to reduce risks of exposure.

The parasite usually spreads through food or water contaminated with feces, according to the Centers for Disease Control and Prevention. It does not typically spread person-to-person.

Foodborne outbreaks of cyclosporiasis in the past have been linked to various types of imported fresh produce, such as raspberries, basil, snow peas, mesclun lettuce and cilantro, according to the CDC.

At least 31 other states have reported cases of cyclosporiasis, according to an ABC News tally, analyzing CDC data and state health department data.

As of Friday, New York has reported the second-highest number of cases at 470 cases since May 1, followed by Ohio at 364, state health officials told ABC News. Meanwhile, Illinois and Florida are each reporting more than 100 cases as of Friday, according to their respective health departments.

The CDC said it has confirmed 843 domestic cases from May 1 to July 9. The agency wrote on its website that it is "aware that states are likely to report higher case counts of cyclosporiasis than reflected in CDC data and is working closely with states to update numbers as additional cases are confirmed."

The agency said it expects a six-week reporting lag between illness onset and case reporting to the CDC as it receives and reviews the data.

Cyclosporiasis is treated with the oral antibiotic trimethoprim-sulfamethoxazole (TMP-SMX), commonly sold as Bactrim, Septra and Cotrim, and taken for 10 days, according to the CDC.

The agency says people can prevent infection by thoroughly washing produce, cutting away bruised or damaged parts of fruits and vegetables and refrigerating pre-prepared or pre-cut produce.

Additionally, the CDC recommends washing hands thoroughly with soap and water before handling or preparing raw fruits and vegetables.

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