How Public Health Officials Use Data to Protect a Community

Over the course of her career, Dr. Janet Berreman has relied on data to identify, understand, and guide her response to community health needs. One source of that data comes from syndromic surveillance, an automated data feed that can act as an early warning system for emerging health threats. Dr. Berreman discusses how she uses syndromic surveillance in her role as Kauai’s (Kauaʻi’s)* District Health Officer to respond to disease outbreaks and protect public health.

This interview has been edited for clarity and length.

What is syndromic surveillance?

It’s largely anonymous health care data that health officials can use to identify if something unusual is happening or threatening the health of a community in real-time. Syndromic surveillance originated in relation to bioterrorism following the anthrax attacks after September 11, 2001, but now we use it to monitor all sorts of things that can affect our communities’ health.

How does syndromic surveillance work?

Courtesy of the subject

Syndromic surveillance is the automated, electronic, systematic collection and analysis of health care data from participating emergency departments and urgent care centers. The data collected includes triage notes, discharge diagnosis codes, and facility location but does not include personally identifiable information, such as the patient’s name or date of birth. The data is typically submitted to the Centers for Disease Control and Prevention’s National Syndromic Surveillance Program, from which state and local health departments can access and use that information to understand local health care needs, evaluate ongoing public health practices, and identify potential health threats.

Because syndromic surveillance uses near real-time data, it can act as a valuable early warning system for outbreaks of dangerous diseases and other important health conditions. For example, if there’s an influx of people showing up in emergency rooms or urgent care clinics with certain symptoms, like a sudden onset fever and cough, it’s a warning that something could be up. You don’t know if it’s a virus or something more serious, like a case of anthrax poisoning, but you know that it’s something to pay attention to.

How is syndromic surveillance different from other forms of disease reporting?

Syndromic surveillance is based on symptoms rather than confirmed diagnoses. It's also a fully automated form of reporting. Those two things combined mean data collection happens before other types of disease reporting that a provider or laboratory may submit. It's also more complete than other types of reporting because it captures the symptoms of everybody who comes through the emergency room, not just people with a specific diagnosis.

That said, it’s less specific because you don’t generally have a confirmed diagnosis and the data includes everyone with a certain set of symptoms. Those people may in fact have several different diseases or conditions. It’s often a warning rather than a confirmation. It tells you what to be aware of. Whereas, if I get a lab report that's positive for E. coli, then I know this person has E. coli. But by that point, that person was probably sick a few days ago, so they've likely already spread it to other people.

When we have early warning of unusual symptoms—leading us to suspect a disease outbreak—before there are lab reports, we can warn physicians to look out for signs of whatever it is we’re concerned about.

Do you have an example of when syndromic surveillance has helped you identify a threat? Or, alternatively, put people’s mind at ease?

Here in Hawaii (Hawaiʻi), there was a measles detection in the wastewater recently. We were able to use syndromic data for people presenting with symptoms consistent with measles—a rash and a fever. Over a certain period, we looked for an increase in people coming to emergency rooms and urgent cares with rashes and fevers. It turns out that there was an increase in symptoms, but it wasn't measles—it was hand, foot, and mouth disease, which is a common childhood illness. So we let folks know to look out for symptoms of that, but that there probably wasn’t a measles outbreak.

Kauai (Kauaʻi) also had a norovirus outbreak recently. Did syndromic surveillance help you identify and address that situation?

Yes, it did. In 2024, we received a report from a resident that an individual had gotten norovirus while hiking the Kalalau Trail on Kauai (Kauaʻi). That information was really concerning because there are a lot of opportunities for norovirus to spread on the trail.

Norovirus is extremely contagious. It spreads easily from contaminated surfaces or water, and hand-washing is the best protection. The restroom facilities along the trail are limited and quite primitive. People don't usually bring in enough water for their whole time on the trail because it’s a 12- or 13-mile hike there and back. So people are filling their water bottles from the waterfall or stream. They're washing or bathing in the waterfall, in the ocean, or in the cave.

So when we learned about the case, we closed the park to allow for cleaning and environmental testing. And we created a survey to distribute to the hikers who were permitted on the trail during the period the individual had gotten sick to help us understand when, where, and to who else that may have happened.

We also realized that many people who were sick had probably already been out in the community by the time we reached them, so they could have spread norovirus to lots of other people who didn’t hike the trail. That's when we thought, Well, why don't we try some syndromic surveillance and see if there's been an uptick in people coming into emergency rooms and urgent care with vomiting and diarrhea, without a known cause. So we worked with the Department of Health folks on Oahu to look at syndromic surveillance data on Kauai, and we were able to confirm that there was not any uptick in those symptoms.

So in this particular case, we didn’t use syndromic surveillance as an early warning, we used it to watch for signs of disease spread beyond the people who were hiking the trail. And the surveillance reassured us that our efforts to control disease spread had been effective.

You talked about how you use syndromic surveillance to protect public health. Why is public health important in the first place?

When public health is working as it should, it is making sure that everyone in the community it serves can live their best, healthiest lives for as long as possible. Syndromic surveillance helps us protect public health and the community.

Public health allows you to drink tap water. Public health means that when you visit Hawaii (Hawaiʻi), you can swim in the ocean and not get sick. Public health ensures that wastewater is purified before it's released anywhere into our environment. Public health monitored air quality after our volcanoes erupted and after the fires in Lahaina. Public health is why you can feel confident eating a meal that you buy at a restaurant. Public health makes it safe to gather in a room with your colleagues or your family, and at school, at a social event, at a concert, or at a community event—and not have to be unduly concerned about getting sick.

Being able to drink and play in the water, eat the food, breathe the air, gather with the people you love, and live as healthy a life as possible for as long as possible—those are public health’s responsibilities.

*The ʻokina (ʻ) represents the glottal stop consonant, or a pause in speech, in the Hawaiian language. It is a symbol of Hawaiian identity that allows for accurate pronunciation and meaning when spoken.