On this episode of “The State We’re In,” State Epidemiologist Dr. Benjamin Chan of the N.H. Division of Public Health talks about cyclospora, the infectious parasite that’s been involved in a massive national outbreak that so far includes dozens of cases in New Hampshire.
By Rosemary Ford and Caitlin Agnew
This article has been edited for length and clarity.
Melanie Plenda:
For those who have missed the recent news reports, can you tell us what cyclospora is and why people are concerned?
Benjamin Chan:
Cyclospora is an intestinal protozoan parasite. It’s not something that’s usually life-threatening, but it causes profuse, watery diarrhea. It can also cause things like abdominal cramping, loss of appetite. People can have nausea and vomiting, although perhaps the vomiting part is less prominent than with other types of intestinal infections. Most people with a normal healthy immune system will get better on their own over time, but they can have prolonged symptoms.
If somebody thinks they might’ve been exposed to cyclospora and has on-going symptoms of watery diarrhea, for example, there is testing that can be done, and that testing can be important to identify an infection. There are treatments, antibiotics that can be given, that can help lessen the severity, shorten the duration of illness.
This is, unfortunately, a relatively common infection that occurs this time of year. It’s spread through contaminated water and fresh produce. Usually what we say is that it’s spread through the “fecal-oral” route. That means it’s spread when somebody has cyclospora in their stool, and that stool contaminates water, and that water is used to irrigate crops in another state or another country and then the contamination then gets on the fresh produce. Then, when it gets shipped to somebody and they eat it, they can become infected with cyclospora. This is how outbreaks happen, and historically, this is a parasite that is known to cause outbreaks.
We've had cyclospora outbreaks in berries and lettuce, cilantro and other fresh produce in the past. We’re seeing a very large increase in cyclospora infections nationally, this year — that’s what people are hearing about in the news. Thousands of cases identified in other states like Michigan and Ohio have led to a recall of lettuce. That lettuce [identified at the start of these cyclospora outbreaks] has come from a certain area of central Mexico and been distributed nationwide to many other states across the country, including New Hampshire.
Melanie Plenda:
Can we talk a little bit about how New Hampshire has been impacted by this?
Benjamin Chan:
Cyclospora is a reportable disease, meaning that if a provider or a laboratory diagnoses somebody with cyclospora, it gets automatically reported to the Division of Public Health so we can investigate, try and get some idea about whether there could be an outbreak — for example, related to contaminated food that might need to be recalled.
We’ve been watching what’s been happening at a national level, and every year, typically, in New Hampshire, we have fewer than 10 people diagnosed with cyclospora. Currently in New Hampshire, and these numbers are on our website, we have a total of nearly 80 people so far, in 2026, that have been diagnosed with cyclosporiasis.
Melanie Plenda:
Do you have a sense of why it’s different this year rather than previous years?
Benjamin Chan:
It’s not entirely clear what’s different this year. We do know that this is an organism that can lead to large outbreaks, and we don’t always have a good picture of what’s happening at a national level.
The national outbreak was first recognized when another state identified a large increase in cyclospora infections that were being reported to the state health department. They investigated, as most states do across the country, and they identified that a majority of people being reported to them ate at Taco Bell. That led to a nationwide recall. That’s sort of how this initially has played out.
As more and more attention and awareness has come to this outbreak, that has led to more testing. Factored into this is the idea that probably every year people get cyclospora infections — they develop symptoms, they don’t seek testing because it’s not regularly ordered, or routinely available, and they get better on their own, so they’re never tested, never identified. But in the setting of a large national outbreak, where we’ve done messaging to the public and to healthcare providers, it raises awareness of the fact that there was this outbreak.
The more testing you do, the more people are identifying the infection, and more testing leads to more infections that are identified and then reported to public health so that they can be investigated. I think there’s going to be more information coming in the next days and weeks around potentially other sources of contamination. But again, this is an organism that we know causes outbreaks, and this is the time of year when we would expect to see outbreaks. The numbers we are seeing are much, much larger than historically what we’ve seen in the past.
Melanie Plenda:
What should people do? Should they be avoiding all lettuce or fresh produce? How can they handle this?
Benjamin Chan:
I think there are a number of steps that people can take to protect themselves if they’re concerned about cyclospora.
It’s generally recommended that people wash their fresh berries and fresh produce to the extent possible. If people are concerned that a vegetable might be contaminated they can cook it — cooking will kill the cyclospora parasite. Also they should make sure that they have good handwashing, make sure there’s not cross-contamination happening in the kitchen — between cutting boards, washing the counters, washing the utensils.
The other steps that people can take is just to be aware of where their fresh produce is coming from. There are, this time of year, lots of different farmers markets, particularly in New Hampshire, that are selling locally grown, fresh produce. There are companies and businesses out there that, regarding lettuce, grow lettuce in greenhouses, with much lower risk of contamination. There are products that are out there that people can take advantage of that are either locally grown or grown in ways that reduce or minimize the contamination, particularly for lettuce.
We still recommend and generally promote people to eat fresh vegetables, fresh fruit, but there are steps people can take to make sure they’re minimizing the risk for food-borne infections.
Melanie Plenda:
I want to thank you so much for joining us today, Dr. Chan. All great information.
“The State We’re In” is a weekly digital public affairs show produced by NH PBS and The Marlin Fitzwater Center for Communication at Franklin Pierce University. It is shared with partners in the Granite State News Collaborative, of which both organizations are members. For more information, visit collaborativenh.org.