WASHINGTON – If you escaped flu infection this year, you have one person to thank: Mother Nature, whose mild winter seems to have put the virus under the weather.
Flu cases are down overall in Maryland, health officials say, but a recent spike in the virus reminds us the season is not over.
Maryland health department officials recently recorded a slight increase in flu cases, but they are unsure why the virus frequency has fluctuated.
According to Katherine Edwards, professor of pediatrics at Vanderbilt University, because of the extensive variety of influenza causes, determining the actual trigger for the disease is a daunting task.
“What influences influenza season is a very difficult thing,” Edwards said. “There’s just a lot of variability in terms of the strains…. It’s very dependent upon the location; it’s very dependent upon the mingling of people.”
However, an overall drop of cases could be attributed the mild winter seen across much of the country, according to Howard County Health Officer Peter Beilenson, who said that warmer temperatures usually encourage people to venture outdoors, which prevents germs from spreading in close quarters.
“It’s been a very light flu season, and in part that may well be that people are out more,” Beilenson said. “It’s a fallacy that people get sick more during the winter because it’s cold out — it’s because people are inside.”
The National Weather Service recorded last month as the fourth-warmest January in history, according to NWS spokesman Chris Vaccaro. Temperatures reached 50 degrees or higher for 14 days, with five of those days soaring to over 60 degrees. The area has seen 1.7 inches of snowfall so far, compared to totals of 10.1 inches last year and 56.1 in 2010, when the D.C. area endured two severe snowstorms in one season.
But despite the overwhelming amount of data indicating a mild winter, there is no actual proof supporting the belief that this warm weather diminishes the influenza virus.
“There are some hypotheses that have been generated that … have never been fully proven that suggest flu viruses may like lower temperatures, lower humidity,” said Tom Skinner, spokesman for the Centers for Disease Control and Prevention. “We at CDC don’t have any proven scientific evidence to suggest that weather … has a direct impact on respiratory diseases, including influenza.”
Maria Said, an epidemic intelligence officer at the Maryland Department of Health, said mild weather could be one of many reasons why the virus is less prominent this year.
“It would be really difficult to say that it’s because of the warm weather, because there are so many different factors that affect the rates of disease,” Said said.
She added that it remains unclear what the recent rise in cases could mean for the rest of the season.
“We’re starting to see a rise, and whether that continues to rise or tapers off … it’s difficult to say,” Said said. “We’re not sure in what direction it’s going to go … I think we’re still watching to see what will happen.”
A late blast of flu activity could serve as a warning for next year, Edwards said.
“The strain that circulates at the end of the season may be a harbinger of what’s going to happen the next season,” Edwards said. “Nobody has the magic prediction to see what things will happen or what strains will circulate.”
In addition to dwindling flu cases, Physicians at Doctors Express clinics throughout the D.C. area have also noticed a higher-than-usual number of respiratory illnesses including bronchitis and allergies, which Doctors Express founder Dr. Scott Burger said is directly related to erratic temperatures.
“If someone gets sick and then it gets cold, we go inside for a few days. We spread it and then it gets warm, and we go back out into the community,” Burger said. “The warmer temperatures have allowed viruses that wouldn’t be active this time of year to remain active.”