An outbreak of diarrhea caused by the Cyclospora parasite has surprised health authorities in Michigan and Ohio, with more than 3,000 cases reported to date. Despite the focus on lettuce and leafy greens, officials emphasize that a precise source has yet to be determined.

Michigan has so far recorded 2,640 cases, including 44 hospitalizations, while Ohio has 361 cases with at least 46 hospitalizations, CNN en Español reports. The incidence of this disease appears to be underestimated due to the difficulty of diagnosing it, highlighting the need for more robust surveillance.

“Preliminary information indicates that lettuce is a common commodity that appears frequently during research,” said Dr. Natasha Bagdasarian, Michigan's chief medical officer.

Important considerations

Identifying the source of the outbreak is complicated by the nature of Cyclospora. The count of cyclosporiasis cases is slow and may require patients to remember what they ate weeks ago, reports CNN.

Cyclospora itself is a pathogen that is more difficult to track than others. For example, for some foodborne pathogens, such as E. coli bacteria and salmonella, scientists can sequence their DNA. It doesn't work exactly the same with cyclospora, says Jennifer McEntire, a microbiologist and founder and CEO of Food Safety Strategies.

"In the case of bacterial pathogens, the technology is quite advanced and the organisms are really very, very simple. It's like reading a children's book compared to reading War and Peace, with Cyclospora being War and Peace," McEntire said. “They are all letters of the alphabet, but they are not the same,” he said.

In addition, genomic tests to detect cases are complicated and the lack of resources following cuts to public health systems is evident.

Although the Centers for Disease Control and Prevention (CDC) continues to monitor the situation, the FoodNet system, which previously offered comprehensive coverage, has reduced its reach.

Recommendations for the population

While investigating, health authorities recommend washing fruits and vegetables well and opting for whole lettuce instead of pre-washed ones.

Despite early interventions, identifying the origin of the outbreak is a long and complicated process that requires the collaboration of those affected.

“The Food and Drug Administration (FDA) and CDC are actively working with state partners to identify the source of the increasing number of illnesses,” Emily Hilliard, a spokesperson for the US Department of Health and Human Services, said in an emailed statement.