Epic Epidemiology
4:23 pm
Thu January 16, 2014

How Do Scientists Track Connecticut Flu Outbreaks?

Officials from the Connecticut Department of Public Health say there have been 1,029 influenza reports so far this season.
Officials from the Connecticut Department of Public Health say there have been 1,029 influenza reports so far this season.
Credit Stacey Newman/iStock / Thinkstock

Getting an accurate count on flu numbers can be tricky. More than 1,000 cases of flu have been reported in Connecticut this season, but how does the Connecticut Department of Public Health arrive at that number?

Lynn Sosa is the deputy state epidemiologist. She said a lot of people get the flu, but never get tested in a hospital. "They stay home like they are supposed to and they get better on their own. They never seek medical advice," she said.

That means the DPH can't rely on just confirmed reports of flu from hospitals. Sosa said they they need to cast a wider net, looking at a lot of different numbers to calculate the severity of a flu season. "We look at how many people are going to the emergency room with what we would call the 'fever flu,'" Sosa said. The DPH also has a group of "sentinel" health care providers. "Who will voluntarily tell us, these are how many people I've seen in my office with a flu-like illness," she said.

The DPH also looks at hospital admissions for pneumonia. "That's not necessarily always from the flu, but certainly during this time of the year some of those can be attributed to the flu," Sosa said. Finally, there are the more traditional numbers, where Sosa actually counts the number of confirmed influenza cases at hospitals around the state. (In case you're curious, there's been 218 so far.)

A breakdown of the different types of confirmed influenza strains in Connecticut as of mid-January.
A breakdown of the different types of confirmed influenza strains in Connecticut as of mid-January.
Credit Connecticut Department of Public Health

"All of these things together are what give us a better sense of what is going on in the state with flu," Sosa said. The DPH database is then updated weekly to provide a rolling snapshot of how the flu is affecting the state. So far, influenza has been spotted in all 8 Connecticut counties. There have been three flu-related deaths. Fairfield County has the most reported cases -- at 342.