TUESDAY, Feb. 3 (HealthDay News) -- There are far fewer cases of flu in the United States so far this year compared to last year, a sign that the nation may be in for a relatively mild flu season, experts said Tuesday.

But, the experts also said they're keeping a close watch on bacterial infections such as methicillin-resistant Staphylococcus aureus (MRSA). MRSA is resistant to certain antibiotics and can strike flu patients -- particularly hospitalized ones -- and is potentially fatal.

"The influenza activity we have seen in the United States has been relatively mild in comparison to last season," Nancy Cox, director of the U.S. Centers for Disease Control and Prevention's Influenza Division, said during a teleconference.

So far, the states with the most cases of flu are New Jersey and Virginia, Cox said, adding that hard numbers are difficult to come by, so health officials are relying on anecdotal reports.

The number of patients with flu that doctors are seeing is also well below the seasonal baseline. The national baseline is about 2.4 percent -- the percent of patients with flu symptoms seen by doctors, Cox said.

"That is unusual for this time of year and is indicative of a relatively mild influenza season," she said.

Also, deaths from pneumonia associated with influenza are well below the epidemic level, Cox said.

The most common flu virus this year is influenza A -- primarily the H1 viruses, Cox said. This is one of the groups of viruses included in this year's flu vaccine, she said, adding that the vaccine also includes AH3 and influenza B viruses.

Cox noted that the H1 strains of the influenza virus are resistant to the commonly used antiviral medication Tamiflu.

"We expect that influenza activity will continue to increase during the coming weeks before the season peaks. It's not too late to get your influenza vaccination," she said.

Despite the good news so far, health officials said they were concerned about the increase in bacterial infections associated with flu, including bacterial pneumonia and MRSA.

"Bacterial infections kill many of the people who die from influenza complications," Dr. Andrew Pavia, a member of the Infectious Diseases Society of America (IDSA) Task Force on Pandemic Influenza, said during the teleconference.

MRSA has also emerged as an infection responsible for deaths among healthy people after influenza, not just those who have been hospitalized, Pavia said. "To date, our planning has not really gotten us ready to deal with that threat," he said.

Pavia said that, last year, the father of actress Cameron Diaz came down with the flu, then a few days later developed pneumonia with MRSA and died. "This is the kind of threat that we need to able to prepare for in a pandemic," he said.

During the 2006-07 flu season, of 74 children in the United States who died from flu, 22 also had staph infections, about 73 percent of which were MRSA, according the CDC.

The CDC says that every year an estimated 5 percent to 20 percent of the U.S. population gets the flu, more than 200,000 people are hospitalized from complications, and about 36,000 people die from the disease.

Meanwhile, experts are still worried about the possibility of a bird (avian) flu pandemic.

"Since 2004, we have been dealing with a large public health issue, which is the spread of avian influenza," Dr. Keiji Fukuda, head of the World Health Organization's global influenza program, said during the teleconference. "In the past three months, we have continued to see a great deal of activity. Since then, we have had about 16 people get infected," he said.

Fukuda said that, even though there has been progress in controlling the virus in birds, it remains widespread and persistent. "In the assessment of WHO, the threat of pandemic influenza remains as high as ever -- it remains a public health priority," he said.

Bird flu isn't the only flu virus capable of a pandemic, Fukuda said. "Right now, many organizations around the world are keeping watch on other viruses," he said.

Tuesday's teleconference was part of the Seasonal and Pandemic Influenza 2009 Symposium in Washington, D.C., sponsored by the Infectious Diseases Society of America.

More information

For more on flu, visit the U.S. Centers for Disease Control and Prevention.

SOURCES: Feb. 3, 2009, teleconference with Nancy Cox, Ph.D., director, Influenza Division, U.S. Centers for Disease Control and Prevention; Andrew Pavia, M.D., Infectious Diseases Society of America Task Force on Pandemic Influenza; Keiji Fukuda, M.D., M.P.H., head, World Health Organization's global influenza program; Seasonal and Pandemic Influenza 2009 Symposium, Washington, D.C.

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