Massachusetts is now on the list of states reporting a cyclospora outbreak

Massachusetts has been added to a growing list of states linked to a multistate cyclospora outbreak, with 147 cases reported in the state so far this season.

The U.S. Food and Drug Administration added Massachusetts and Maine to its list of states affected by the outbreak, which had sickened 9,481 people across 17 states as of Aug. 13.

Massachusetts has reported 147 cases between May 1 and Aug. 1, according to the state Department of Public Health. While that is a higher-than-usual seasonal total, the number remains within the state’s historical range, a DPH spokesperson said.

Annual case totals in Massachusetts have ranged from 23 to 211 between 2016 and 2025.

The next state update is expected in early September and will include cases reported through Aug. 31.

The peak season for cyclospora, a parasite that can cause severe diarrhea and other gastrointestinal symptoms, runs from May 1 through Aug. 31, according to DPH. 

Because the parasite has a relatively long incubation period and more people may seek testing amid increased attention to the outbreak, the state expects to receive additional case reports into the fall.

What’s behind the outbreak?

The FDA has said recalled iceberg lettuce was distributed to food service locations in Massachusetts. Investigations by local boards of health and DPH epidemiologists have identified several small clusters of cases among Massachusetts residents that appear to be linked to the lettuce.

The Centers for Disease Control and Prevention has also updated its outbreak map to show cases in Massachusetts associated with the recalled lettuce.

The FDA said it has begun an on-site inspection and sampling at Taylor Farms de Mexico in coordination with Mexican officials. The agency said it remains confident that all recalled iceberg lettuce connected to this specific outbreak has been removed from the market.

How to reduce your risk

DPH recommends several steps to reduce the risk of cyclospora infection:

• Wash your hands with soap and water for at least 20 seconds before and after handling or preparing fresh fruits and vegetables.
• Rinse produce under clean, running water, even if it is labeled pre-washed. Wash produce before peeling it, and use a clean vegetable brush on firm fruits and vegetables such as cucumbers and melons. Do not use soap or bleach to wash produce. Rinsing is an important step, but it does not reliably remove cyclospora.
• Remove outer layers of produce when possible. Peel produce such as cucumbers, and remove the two or three outer layers from leafy vegetables such as lettuce.
• Cook produce to at least 158 degrees Fahrenheit. Cyclospora cannot survive at those temperatures.
• Prevent cross-contamination by washing countertops, cutting boards, and utensils with hot, soapy water after they come into contact with fresh produce.

Beth Treffeisen is a general assignment reporter for Boston.com, focusing on local news, crime, and business in the New England region.