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 34 states since May 1.
According to the most recent data from the Centers for Disease Control and Prevention, published Tuesday, 1,645 cases of cyclosporiasis have been confirmed in the US, while over 5,100 cases need to be analyzed to determine if the infection was caught domestically.
The CDC said case counts are likely to be higher than its data suggests and it is working with states to keep numbers updated.
The states with the most known cases of cyclosporiasis include Michigan and New York
According to the latest CDC data published Tuesday on cyclosporiasis cases confirmed between May 1 and July 13, seven states have seen the biggest spike since last Thursday:
| State | Range of people confirmed sick as of July 9 | Range of people confirmed sick as of July 13 |
| Michigan | 161–300 | 501–900 |
| New York | 81–160 | 161–300 |
| North Carolina | 31–80 | 81–160 |
| Indiana | 11–30 | 31–80 |
| Connecticut | 1–10 | 11–30 |
| Kansas | 1–10 | 11–30 |
| West Virginia | 1–10 | 11–30 |
- Illinois, Kentucky, New Jersey, and Texas also have 31 to 80 cases each
- Florida, Georgia, Oklahoma, Pennsylvania, Tennessee, and West Virginia have 11 to 30 cases each
According to the CDC, the remaining states have identified one to 10 cases each: Alaska, Arizona, Arkansas, California, Colorado, Iowa, Louisiana, Maryland, Massachusetts, Minnesota, Nebraska, New Hampshire, Ohio, Rhode Island, Utah, Washington, 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.
Connecticut: 35 cases confirmed as of July 13.
Florida: 50 between May 1 and July 4, according to its Reportable Diseases Frequency Report.
Illinois: 240 as of 7 a.m. Wednesday, including 111 caught domestically.
Michigan: On Tuesday, the Michigan Department of Health and Human Services said 3,309 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.
New Jersey: As of July 11, 46 reports of cases acquired domestically.
North Carolina: 307 cases and 13 hospitalizations as of July 14.
Ohio: As of Thursday, the Ohio Department of Health had reported 364 cases and 46 hospitalizations this year.
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.
