Tuesday, January 10, 2006

Bird Flu IS Among Us

Probe: Bird flu can be mild

New research finds human cases of avian virus more pervasive than thought, but can be easily shaken


January 10, 2006

Thousands of mild human cases of avian influenza have occurred throughout the two-year outbreak in Vietnam - epicenter of the disease in Southeast Asia - suggesting that the infection is far more pervasive than previously thought, new research has found.

The investigation by a team of scientists from the Karolinska Institute in Sweden is not altogether bad news. It suggests bird flu can be so mild in some people that they easily shake the infection without medical attention. And while the new research reveals that infections with the H5N1 virus is more widespread, it also underscores that the strain does not kill 50 percent of people infected with it.

Infectious disease experts yesterday said the research provides a strong counterpoint to growing fears about the infectiousness of avian influenza, especially in light of reports of human cases apparently smoldering in Turkey for months.

"The symptoms most often are relatively mild," wrote Dr. Anna Thorson, lead investigator of a project that surveyed more than 45,000 people in northwest Vietnam where highly lethal outbreaks have led to waves of poultry die-offs.

"Close contact [with sick or dead birds] is needed for transmission to humans," she said.

Thorson, reporting in yesterday's issue of the Archives of Internal Medicine, randomly selected residents in Vietnam's Bavi district and asked them a series of questions about exposure to poultry and having any flu-like illnesses. The study was conducted between April 1 and June 30, 2004. The first human cases were reported in Vietnam in the fall of 2003.

About 80 percent of those responding to the survey reported living in homes that maintained fowl and about 25 percent of those respondents said they lived in homes where birds had become sick or died suddenly. All told, 8,149 people said they had experienced flu-like symptoms, but the illnesses lasted no more than three days. Thorson and her team defined flu-like symptoms as cough and fever. Respondents with direct contact with sick or dead birds were 73 percent more likely to report symptoms.

The research confirms what experts at the World Health Organization have said all along: Close contact with affected birds is key to infection. Infectious disease specialists at the Centers for Disease Control and Prevention have emphasized that human-to-human transmission would be needed to trigger a global flu pandemic on the scale of the 1918 outbreak that quickly circled the globe, killing 50 million people.
Good news, right?

Maybe. After all, viruses mutate at incredibly swift rates. That this particular mutation made the leap and is mild doesn't mean: a) it's stopped mutating or b) that a new mutation, a deadlier mutation, could still make the leap to mammals (and of course, humans).

Let's get through February, and we can all breathe a little easier for now.