Studies Identify Why Avian Flu Not Spreading Among Humans
Studies conducted by two separate groups of researchers have found that the avian flu virus attaches deep within the human respiratory tract, which prevents the spread of the virus through coughs and sneezes and indicates "why the bird flu is not spreading easily from person to person," the Washington Times reports (Howard Price, Washington Times, 3/23).
The studies "suggest that the virus could acquire" the ability to spread among humans by "switching its preference from the cell receptor found in the lower lung, known as alpha 2-3, to the receptor found on cells in the upper airways, known as alpha 2-6," the New York Times reports.
According to Yoshihiro Kawaoka -- a virologist at the University of Wisconsin at Madison and lead author of one of the studies, which was published on Thursday in the journal Nature -- the avian flu virus would have to undergo many mutations before the virus could cause a pandemic.
The second study, which was led by Thijs Kuiken at the Erasmus Medical Center in the Netherlands and appears this week in the journal Science, found similar results. (Wade, New York Times, 3/23).
Kawaoka said the studies do not eliminate the possibility of an avian flu pandemic. He said, "Flu viruses constantly change. Certainly, multiple mutations need to be accumulated for the H5N1 virus to become a pandemic strain" (Washington Times, 3/23).
Nikki Shindo, an influenza expert at the World Health Organization, questioned the conclusions of the studies. Shindo said, "I don't think it directly affects the transmissibility just because it's in the lower respiratory tract" (Regalado, Wall Street Journal, 3/23).
An abstract of the Nature study is available online.
NPR's "Day to Day" on Thursday included an interview with Paul Offit, chief of infectious diseases at Children's Hospital in Philadelphia, about the likelihood that the avian flu virus will become transmissible between humans (Chadwick, "Day to Day," NPR, 3/23).
The complete segment is available online in RealPlayer.
In addition, Department of the Interior Secretary Gail Norton is scheduled to answer questions about the Bush administration avian flu preparations and surveillance plans in an "Ask the White House" chat on Friday at 2 pm ET. A transcript of the chat will be available online.