It's not a perfect sampling, Najera said. For example, it misses Marylanders who do not use computers or who lack access to the Internet.
But the more people who take part, the more reliable the data will be. Australia, a nation of 21 million, enrolled 3,600 people in its surveys. Maryland, with a population of 6 million, is hoping for 2,000.
Howard County health officer Dr. Peter L. Beilenson called the effort "interesting ... modestly useful and it's free." But he cautioned that participants are self-selected and might not be representative of the population at large, including particularly vulnerable groups such as day care providers and people with suppressed immune systems.
"What would we be doing differently with that information?" he asked. "We can always do better, but our main purpose is getting as many people vaccinated as possible, and educating people on how to prevent the spread of the flu."
The Maryland flu tracking survey is just one Internet-based alternative for public health authorities seeking to monitor flu activity. Another is Google search tracking.
When people get sick, the online search engine provider has found, many of them run Internet searches on their symptoms. And Google says the volume of searches on key flu-related terms closely mirrors the volume of flu cases reported by traditional means to CDC.
"By counting how often we see these search queries, we can estimate how much flu is circulating in various regions of the United States," says the company Web site. You can track flu-related queries, state-by-state, at www.google.org/flutrends/.
Nationally, seasonal influenza remains at a "low" level, according to the latest CDC report, for the week ending Nov. 8. It notes "sporadic" activity in 15 states, "local" activity in one state and no activity in the rest.
The CDC has had no reports of pediatric deaths so far this season. The count of adult deaths related to pneumonia and influenza was below the "epidemic" threshold. So far, the Type A flu viruses have dominated the lab results, outnumbering the Type B strains by a margin of 4-to-1.
Maryland health officials continue to urge residents to get vaccinated.
Noting the flu-like illnesses and gastroenteritis that spread through crowds gathered for a papal visit to Australia last summer, they said they expect a similar pattern among the more than 1 million people expected to crowd Washington for the presidential inauguration Jan. 20.
