US map shows cyclospora parasite hot spots, as 5 states see the biggest spikes in diarrhea cases

• 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 weeks of watery diarrhea.

The infection has been reported in 45 states since May 1, according to state-level health department data.

According to Georgetown's Health Security Operations Center, which is tracking both state-level and national data, more than 8,260 cases of cyclosporiasis have been reported in the US, with the bulk of cases spread across the Midwest and mid-Atlantic states.

On Thursday, the US Food and Drug Administration identified shredded iceberg lettuce from a supplier in Mexico that was sent to Taco Bell locations in five states as one source of the outbreak, but there are likely other food sources driving the spread. A source close to the federal investigation confirmed to Business Insider that the supplier is Taylor Farms, one of the largest salad companies in North America.

Business Insider created a map showing the number of cases in each state. It is primarily based on data reported by state health departments, either from their official channels or in statements to local news outlets.

Such data was not immediately available from Georgia, Rhode Island, or Utah, so for those the range of cases given by the Centers for Disease Control and Prevention was used instead.

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

The high number of confirmed cases in Michigan — more than 4,300 — 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," public health expert Katelyn Jetelina wrote in her newsletter, Your Local Epidemiologist, on July 11.

By Thursday, Ohio (1,409), New York (510), Indiana (327), and North Carolina (307) were all reporting more than 300 confirmed cases.

How to avoid Cyclospora, which has been linked to chopped lettuce

The Michigan health department said Monday that ongoing investigations suggest "lettuce or salad greens" are a possible source of contamination, but other foods can't be ruled out.

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 trace back to a definitive source.

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

Health authorities say in order to definitively kill the parasite, cook foods to at least 158 degrees Fahrenheit. Buying whole heads of lettuce and peeling back the outer layer of leaves rather than choosing pre-washed, bagged, or pre-mixed salads is also a good move, if you are more risk-tolerant.

According to the CDC, the typical cyclospora season lasts until late August, and cases could continue to rise until then.