2006-03-21-Researchers identify 2nd strain of bird fluUnderstanding Avian Influenza
2006-03-21-Researchers identify 2nd strain of bird flu
American researchers say the deadly H5N1 form of bird flu has split into two distinct strains, a development that could make it even more difficult to prevent outbreaks among humans.
"Back in 2003, we only had one genetically distinct population of H5N1 with the potential to cause a human pandemic. Now we have two," said Rebecca Garten of the U.S. Centers for Disease Control and Prevention (CDC) at a conference in Atlanta.
The existence of two different types of the avian flu virus could make it harder to develop vaccines to stop the spread of the disease, which has now killed 103 people around the world.
The U.S. team studied 300 samples of the H5N1 virus from infected birds and humans.
Researchers determined that the first known type of H5N1 to make humans sick cropped up in 2003 and 2004, affecting people in Vietnam, Cambodia and Thailand.
The second strain, which showed up in Indonesia in 2005, is the type that has since been showing up most commonly in Europe.
Dr. Nancy Cox of the CDC told Reuters that so far, the second strain is no more easily transmitted among humans than the first one.
"It really doesn't take us closer to a pandemic," Cox said. "It simply makes preparing for the pandemic a bit more difficult."
On Tuesday, Pakistan's agriculture ministry confirmed that H5N1 had been detected in the country for the first time.
The virus showed up on two farms in northwestern Pakistan.
Also, two new outbreaks of H5N1 were confirmed among poultry in northern Malaysia.
Since late 2003, millions of chickens, ducks and turkeys have been slaughtered in an attempt to stop the spread of the disease.