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Flu Viruses Becoming More Resistant To Key Medication

Flu season peaks in February and March in the northern hemisphere. And now more than ever, doctors are concerned that the main drug used to treat this potentially deadly virus is becoming ineffective.

Effectiveness of treatment for flu

Tamiflu is losing its punch (effectiveness). Doctors in the northern hemisphere report flu viruses are becoming more resistant to what was once the best flu treatment available.

At the U.S. Centers for Disease Control (and Prevention), Dr. Alicia Fry analyzes flu viruses. "This year, the prevalence of resistance is very high," she said.

In the past few years, researchers have noticed a change in how one strain of the virus has become resistant to oseltamivir, the generic name for Tamiflu.

"Last year about 12 percent of the Influenza A H1N1 viruses were resistant to oseltamivir, and this season it looks like approximately 98 percent, almost 100 percent, of those viruses are resistant to oseltamivir," Dr. Fry said.

Just two years ago, only one percent of the samples she examined were resistant to the drug.

Resistant strains of flu could lead to possible pandemic

It leaves health officials and doctors concerned about how to treat a possible pandemic and how to care for individual patients.

Dr. Greg Poland of the Mayo Clinic says, "There will be more hospitalizations. And yes, there could be more deaths," he said.

If there is good news, it is that the resistant strain of influenza is no more deadly than normal, unlike the highly lethal bird flu.

But the there is only one, well-tested alternative to Tamiflu: an anti-viral drug called Ralenza. It is given though a dry powder inhaler that many patients find difficult to use. Others cannot use it at all.

"People with chronic respiratory conditions such as asthma, pregnant women and children under the age of seven," Dr. Poland explains.

Best defense against flu

Osiltamivir still works for other strains of influenza, but the Centers for Disease Control is urging doctors to use an older flu-fighting agent if they do not know which strain a patient has. Dr. Fry says prevention may be more important now than ever before.
"The best defense against influenza is vaccination," she said.

But flu vaccines do not offer total protection. So doctors also recommend frequent hand washing and staying away from those who have the flu.

Meanwhile, infectious disease experts are urging the global medical community to find new drugs to combat the flu.

The report from the Centers for Disease Control is in the Journal of the American Medical Association.