The “bird flu” responsible for the deaths of six people in Hong Kong hasn’t so far genetically altered into a more contagious virus that could spark a global epidemic, according to a report released Friday.
While fears of pandemic flu have been quelled for the short term, there is still concern that the virus that has killed thousands of chickens in Hong Kong still may alter into a strain easily transferred to humans.
Also, because researchers continue to be baffled over how the 18 people infected with the virus contracted the flu, scientists at the Centers for Disease Control and Prevention in Atlanta continue to work on a vaccine.
CDC researchers were lead authors of a report on the genetic study of the bird flu virus that appeared Friday in the journal Science.
A flu epidemic begins when a new virus to which humans haven’t built up an immunity appears on the scene and the virus has a genetic makeup that moves easily from human to human, said Tom Skinner, CDC spokesman.
“The bottom line is we haven’t had a new case in humans since Dec. 28; that’s certainly good news,” said Skinner. “If this is a virus transmitted from person to person, it’s not being transmitted efficiently, and that’s good news.”
The CDC researchers studied genetic material collected in Hong Kong from people who contracted the flu virus. Their study showed that the virus, called avian influenza A-H5N1, did not mutate or combine with human flu genes. A bird flu that acquired human flu genes could spread rapidly from person to person.
“It’s the same virus that the birds have. It hasn’t mutated, which is what we believe would have to happen in order for it to turn into a pandemic,” said Dr. Robert A. Lamb, a Northwestern University influenza virus expert who proofread the article for the journal.
To contain the virus, Hong Kong authorities slaughtered 1.2 million chickens, a move that experts such as Lamb say was “essential” to contain the virus.
So far, scientists haven’t found evidence of human-to-human transmission of the virus.
Usually, bird flu viruses don’t infect humans, and the spread of the virus to people alarmed public health officials. But sometimes, bird flu viruses and human flu viruses can mix at the cellular level. This typically occurs in a pig, which is capable of being a host to both the bird and human flus. The two strains mix; the genetic “reassortment,” as scientists call it, can create a novel and strange strain that potentially could lead to a pandemic flu strain.
“This (Science report) allows us to be a bit more optimistic, although still cautiously optimistic,” said Dr. John Flaherty, an infectious disease specialist at the University of Chicago. “There is still a lot more we need to know.”
CDC researchers also found that one reason the bird flu virus may be so lethal is that it doesn’t appear to remain as a respiratory infection but instead seems capable of spreading throughout the entire body.
