BSCS Biology: A Molecular ApproachUnit 5: Responding to the EnvironmentIn the NewsAvian Flu Virus: An Emerging Threat Does this sound familiar?
If you are thinking that this virus sounds like the human immunodeficiency virus (HIV), you are right. But these characteristics also describe a new threat-avian (bird) flu virus. Avian flu viruses occur naturally, and they usually cause only mild infections among wild birds. But every so often a highly contagious strain emerges that kills domesticated birds - chickens, ducks, and geese - with astounding speed. Since late 2003, avian flu virus has killed over 100 million birds in Asia. Avian flu virus is an influenza type A virus. There are over 20 subtypes of type A viruses, and the current avian flu virus is known as subtype H5N1. It does not normally infect humans. However, since 1997 scientists have been recording cases of poultry-to-human H5N1 transmission. With the widespread and devastating avian flu outbreaks of H5N1 in Asia, several dozen people have died. Scientists have not yet documented prolonged human-to-human spread of H5N1. Most of the people who have suffered from H5N1 acquired it from direct contact with infected birds or their wastes. However, given that the virus kills over 60 percent of the humans it infects, the advent of human-to-human transmission would be devastating. Scientists fear that human-to-human transmission of the virus could happen quite easily. Dr. Julie Gerberding, head of the Centers for Disease Control and Prevention, says, "The concern in Asia is that we have this highly pathogenic strain of influenza, circulating widely, and there are really wonderful opportunities for this virus to either reassort [its genes] with human strains of influenza, or with other avian species, and evolve into a strain that has whatever that secret ingredient is that allows it to be effectively transmitted from person to person." Gerberding is pointing to the tendency of influenza type A viruses to intermingle their genes with large chunks of genes from other types of viruses. A combination of H5N1 with an unlucky set of human flu genes could mean a deadly flu with human-to-human transmission. The human immune system would likely not recognize this new viral player. Humans, at least initially, would not be able to mount an effective defense again the virus. Many scientists relate the potential threat from avian flu virus to the 1918 influenza pandemic that killed 20-40 million people worldwide. Accordingly, a global effort is underway both to manage outbreaks of avian flu among bird populations in Asia and to develop effective vaccines and treatments against a new influenza strain. Sources: http://www.aaas.org/news/releases/2005/0221flu.shtml http://www.cdc.gov/flu/avian/gen-info/avian-flu-humans.htm http://www.cnn.com/HEALTH/library/DS/00566.html 1918 flu facts: http://www.stanford.edu/group/virus/uda/ |  |
