Flu is “widespread” in 42 states, including Maryland, according to the Centers for Disease Control and Prevention, bearing out a prediction that this could be a particularly rough year for seasonal influenza.

A Jan. 4 alert from the CDC warned that “influenza activity continues to increase in the United States with most of the country now experiencing high levels of influenza-like-illness,” based on data from Dec. 23 through 29, the most recent available.

The outbreak swelled rapidly in Maryland, growing from “sporadic” in the week ending Dec. 1 to “widespread” two weeks later, according to the Maryland Department of Health and Mental Hygiene. By the end of December, there were “increased” levels of flu-like symptoms reported throughout the state.

Hospitals don’t routinely identify the specific virus afflicting people with flu-like symptoms, including fever, lethargy and a runny nose, but cases of the symptoms have spiked recently, suggesting that flu viruses are circulating locally, said Dr. Vipul Kella, vice chairman of the emergency department at Medstar Southern Maryland Hospital Center in Clinton.

“Especially within the last month, we’ve seen a pretty significant rise in emergency department patients coming in with flu-like symptoms,” Kella said. In most cases, “supportive care” like rehydration and anti-fever drugs are all that is required; although, if the disease is caught early, treatment with Tamiflu, an anti-viral drug, can shorten the course of the illness by about a day, he said.

Flu often can be managed at home, but medical help can be important for the very old or the very young, people with compromised immune systems and those with chronic medical conditions, Kella said.

The flu season seems to be peaking early this year, said Dr. Dianna Abney, acting director of the Charles County Department of Health, who recommended “hand washing, hand washing, hand washing,” to avoid getting sick.

Other preventive measures include staying generally healthy with a good diet, exercise and rest, she said. She also urged people with flu-like symptoms to “stay home” to avoid infecting others, and to cough into the crook of the arm, not the hand, to avoid spreading the virus.

No one really knows why flu seems particularly widespread this year, she said. But there is one bright spot: Scientists did a good job of predicting this year’s strains, so vaccinations are likely to be particularly effective, Abney said.

“The flu that we’re seeing is exactly what’s in the vaccine,” she said.

The vaccination, which contains two types of Influenza A virus and one type of Influenza B, can take a few weeks to be effective, so it is important to be immunized as soon as possible. The health department has held eight free flu vaccination clinics this year and will again offer the vaccine from 10 a.m. to 4 p.m. Jan. 30 at its White Plains offices. Local pharmacies are selling vaccinations as well, she said.

Vaccination does not ensure that a person will not be infected; Kella said he has seen “quite a few cases despite having had the flu vaccine.”

But the vaccine does reduce the risk, with a 2009 study in The New England Journal of Medicine suggesting that the “flu shot,” which uses an inactivated form of the virus, was 60 percent effective against flu A during the 2007-08 flu season. A different form of the vaccine, a nasal spray using viruses that are weakened but not killed, was less effective, though it did prevent some illnesses, the authors concluded.

Strains of Influenza A virus, the generally more severe type, predominate in the CDC region including Maryland, comprising roughly the mid-Atlantic states, according to the CDC website. During four weeks in December, 94 percent of the 914 positive flu test results reported from the region were Influenza A strains, and another 4 percent were Influenza B. Less than two percent, 18 cases total, were 2009 H1N1 virus, dubbed “swine flu,” which caused a pandemic in 2009 and 2010 and continues to circulate at lower levels in the United States, the CDC website states.

emitrano@somdnews.com