Bird Flu Threat Rises
WHO Expert Panel: World 1 Step Closer to Killer Flu
May 20, 2005 -- The world is one step closer to a devastating killer flu pandemic, World Health Organization (WHO) experts suspect.
Two developments in northern Vietnam spur the renewed concern:
- Deadly bird flu infections are being seen in larger clusters of people -- with a much wider age range -- than ever before.
- The virus is changing in ways that suggest it may be adapting to humans.
- Also of concern is the revelation that one virus isolate was partially resistant to TamiFlu, the only effective treatment for human infection with type H5N1 bird flu.
Because of these developments, the WHO urgently convened a panel of experts that met earlier this month in Manila, Philippines. The panel's report, written on May 11, was released yesterday.
"All countries, both those affected and unaffected by avian H5N1 ... should move ahead as quickly as possible and develop or finalize practical operational pandemic preparedness plans," the panel advised.
Another Tick of the Pandemic Clock
The WHO lists six stages leading from the detection of a new flu virus in animals to a global human flu pandemic. So far, the H5N1 bird flu has been at stage 4: small, highly localized clusters of human infections. At this stage, the virus cannot spread easily from person to person.
The new evidence suggests -- but does not yet prove -- that bird flu may be moving to stage 5. That would mean the virus is becoming increasingly better at person-to-person spread. When stage 6 is reached, there will be rapid human-to-human flu spread and pandemic flu.
It's only a matter of time, says virologist Klaus Stöhr, PhD, DVM, project leader for the WHO Global Influenza Program.
"We are in a situation where we simply have to deal with uncertainties on when this will happen -- not whether this will happen or not," Stöhr said yesterday in a news conference. "We believe a pandemic will happen, but we don't know when and also [we don't know] the severity of the event."
The last flu pandemic was in 1968. That means that this is the first time the world has had the tools in place to track a flu pandemic as it develops. Guénaël Rodier, MD, MSc, director of the WHO Department of Communicable Disease Surveillance and Response, says it's becoming clear that there are many small steps -- rather than alarming leaps -- that lead to a flu pandemic.
"There is no evidence of a big crisis," Rodier said at the news conference. "But there are enough elements to say there may be something going on. ... We have enough data to be concerned. At the same time we don't have enough data to be sure."
"In the last 18 months, we have seen an incremental increase in our concern," Stöhr said. "We do not know if a pandemic can occur next week or next year."