This map shows which states are the hotspots of the parasitic diarrhea outbreak

• There's an outbreak of cyclosporiasis in the US, and Michigan has the most reported cases.
• The cyclospora parasite causes diarrhea and is spread through contaminated food and water.
• We created a map to track which US states have the most recorded cases of cyclosporiasis.

Michigan is the hotspot for an outbreak of cyclosporiasis, an infection caused by a parasite that can trigger diarrhea.

The infection has been reported in 31 states since May 1.

According to the most recent data from the Centers for Disease Control and Prevention, published Thursday, 843 cases of cyclospora have been reported in the US.

The CDC said case counts are likely to be higher than its data suggests and said it is working with states to keep numbers updated.

The states with the most known cases of cyclospora include Michigan and Ohio

As shown in the map above featuring the latest CDC data, the states with the most cases in descending order are:

• Michigan: 161 to 300 cases
• New York: 81 to 160 cases
• Texas, North Carolina, New Jersey, Kentucky, Illinois: 31 to 80 cases each
• Florida, Georgia, Indiana, Pennsylvania, Tennessee, Virginia: 11 to 30 cases each

According to the CDC, the remaining states have identified one to 10 cases each: Alaska, Arkansas, California, Colorado, Connecticut, Iowa, Kansas, Louisiana, Maryland, Massachusetts, Minnesota, Nebraska, New Hampshire, Ohio, Rhode Island, Utah, West Virginia, and Wisconsin.

Some states, including Ohio and Michigan, have issued state-level data that differs from the CDC's. Business Insider contacted the CDC and states with the most cyclosporiasis cases for the latest information, and did not immediately receive a response.

Ohio: On Thursday, the Ohio Department of Health reported 364 cases and 46 hospitalizations this year.

Michigan: On Monday, the Michigan Department of Health and Human Services said 2,640 cases had been reported in the state. Typically, 40 to 50 cases are reported in Michigan annually. The department updates data on hospitalizations on Thursdays: As of July 9, 44 reported cases had been hospitalized in Michigan.

The number of confirmed cases in Michigan doesn't necessarily mean the outbreak started there.

"It is more likely to mean Michigan is better resourced for testing, reporting, and epidemiological legwork, so more of its cases are getting caught and counted," Katelyn Jetelina, assistant professor adjunct of epidemiology at Yale School of Public Health, wrote in her public health newsletter, Your Local Epidemiologist, on July 11.

How to avoid cyclospora, which has been linked to salad and lettuce in Michigan

The MDHHS said Monday that early investigations suggest lettuce or salads are a possible source, but other foods can't be ruled out. "No specific type of produce, grower or supplier has been identified as the source," it said.

Cyclospora spreads through contaminated food and water, and symptoms, including watery diarrhea, nausea, and stomach cramps, can take up to two weeks to show, making it difficult to identify a source.

The parasite is resistant to disinfectants, and washing food doesn't guarantee its removal, as it is particularly good at sticking to produce.

In light of early evidence suggesting that lettuce and bagged salad are potential culprits, Michigan's health department advised:

• Cooking greens to at least 158 F (70 C) is safest.
• Buying whole heads of lettuce rather than pre-washed, bagged, or pre-mixed salads.
• Removing two to three outer layers of leaves.
• Washing the inner leaves thoroughly under clear running water.