Anxiety over the Avian flu virus, known as H5N1, has spread throughout the world and many experts are sounding the alarm that a pandemic is imminent. Still, the nature of the impending health crisis is uncertain, and questions regarding the force of the pandemic and H5N1's role in it remain unanswered. A diverse group of government and academic experts addressed these and other issues at last Friday's Global Biological Threat Symposium, hosted by UW-Madison's Center for World Affairs and the Global Economy.
Pandemics are epidemics—widespread outbreaks of infectious disease—which have spread beyond a region or continent. Currently, the World Health Organization has set the pandemic alert to level three, indicating evidence of no or very limited human-to-human transmission.
According to Hon Ip, a virologist with the U.S. Geological Survey's National Wildlife Health Center, there is a 30 to 40-year cycle between influenza pandemics. Since the last pandemic occurred in 1968, Ip said that we are really overdue.\
The question is whether H5N1 will be the virus that causes it.
At Friday's symposium, Ip said that out of 191 total human cases of H5N1 infection, there have been 108 deaths. According to the WHO, laboratory-confirmed human cases were reported in Vietnam, Indonesia, Cambodia and Thailand, mostly affecting previously healthy children and young adults.
At the disease's current level of transmission, Ip outlined a trio of possible routes of introduction into the United States. Infected individuals could carry the pathogen on their body or on their clothes if they come into contact with diseased poultry or their virulent secretions and feces.
The migration of infected birds, specifically the ducks, gulls and shorebirds that make up the virus's main reservoir, could lead to the introduction of H5N1. Finally, Ip also said the illegal, undocumented shipments of poultry that make their way into the United States with some regularity are a cause for concern.
According to the WHO, poultry and eggs, if properly cooked, do not transmit the virus.
The WHO said that the current risk from Avian influenza is generally low for most people, since transmission from poultry-to-human is still rare and there has not been any sustained human-to-human spread of the virus. However, many experts are concerned that H5N1, the most virulent Avian flu virus to cross the species barrier, could evolve into a strain that can be easily transmitted between people.
So far, H5N1 hasn't demonstrated this ability. According to Eric Noji, former senior policy advisor for Health and National Security for the Centers for Disease Control & Prevention in Washington, D.C, as the virus is transmitted between different species, the pathogen becomes slightly altered as a result of genetic mixing over time, which could lead to a variety of outcomes.
""These subtle genetic changes could lead to an epidemic or a small cold,"" Noji said.
The unpredictable nature of this microevolution makes disease forecasts uncertain, though the WHO, Noji and Ip said that a pandemic, caused by H5N1 or otherwise, is on the horizon.
""Each additional human case gives the virus an opportunity to improve its transmissibility in humans, and thus develop into a pandemic strain,"" according to the WHO's website. ""The recent spread of the virus to poultry and wild birds in new areas further broadens opportunities for human cases to occur. While neither the timing nor the severity of the next pandemic can be predicted, the probability that a pandemic will occur has increased.""\
