Until now, public health authorities have relied mainly on a few dozen physicians, medical labs, hospitals and other health care institutions to report regularly on the illnesses they are seeing.
DHMH epidemiologists also investigate and track outbreaks of flu and pneumonia in schools, nursing homes and other institutions.
Last year, the state confirmed 4,029 cases of seasonal flu, peaking in the second week of February. But that is only a fraction of the actual case volume, missing the people who never seek professional care.
Seeking a larger sample and a more comprehensive yardstick, Najera came across FluTracking.net, a program used in Australia during the past two Southern-Hemisphere flu seasons to find more flu cases via the Internet.
So he adapted it for Maryland. "I believe we're the first in the nation" to use it, he said.
People who sign up online provide their birth date, county of residence, ZIP code and e-mail address. They report whether they've had a flu vaccination and whether they work in a health care setting.
Then, once a week during flu season, they receive an e-mail reminder to log on to the survey's Web site.
There, they're asked whether they experienced a fever, cough or sore throat during the previous week. If so, they're asked whether the illness caused them to miss work, school or other normal activities, a rough measure of severity.
Participants are also asked whether they've received their flu vaccination within the prior week - "a chance to tell us if that's changed," Najera said.
The survey is short, and it does not gather enough information to confirm that the participant has the flu, he said. But the symptoms - fever, cough or sore throat - are the same ones the traditional sentinels report to the health department.
While the questions might pick up some nonflu illnesses, such as strep throat and any number of upper respiratory viruses, they will surely catch influenza cases, too.
"The reasoning is that, during the flu season, the great majority of people with those specific symptoms, more often than not, will have the flu and not similar infections," Najera said. "We call it sensitive, but not specific."
Data on when the flu arrives and where and how it is spreading will be shared weekly with local health departments, health care providers and medical laboratories, helping them to plan their responses.
