Thursday, March 09, 2006

Fireblankets, martens, Belgians and being realistic

WHO wound up their meeting to discuss strategies for dealing with the unprecedented panzootic of influenza A/H5N1 still debating whether it would be possible to nip a human pandemic in the bud by an antiviral "fireblanket" approach, smothering the opening sparks at an origin like southeast asia, China or Indonesia. Those who believe this can be done had taken hope from two mathematical models published last year suggesting that if we had incredible luck, skill and resources this might be possible. There is an old adage in the modeling community that all models are wrong, but some models are useful. As a modeler, I believe this. But you always have to ask, "Useful for what?" Believing they are sufficiently quantitatively accurate to use for this purpose (as opposed to qualitatively informative) is to have both misplaced faith and lack of knowledge about what goes into -- and hence what comes out of -- these models. We have discussed this previously here, here and here.

Two reports today suggest just how futile this idea is. The first is the discovery of H5N1 infection in yet another mammalian species in Europe, the stone marten (AP via CNN). A stone marten is a member of the weasel family. They are pine forest dwellers, less than a foot long, nocturnal and carnivores, living on small animals -- like birds. Various species of marten are widespread and can be found in North America, Europe and central asia. How often they have been infected with H5N1 no one knows as this is not an animal where the disease has been looked for previously. The dying stone marten was found on March 2 on the German island of RĂ¼gen, where the dead H5N1 infected cats were also found. German verterinarians are now saying (in hindsight) it is not surprising, as cats and stone martens have similar prey. But it is another indication that this virus is adapting well to mammals and the more it circulates in them the greater opportunity for mammalian adaptation. I doubt that the antiviral fireblanket has set aside any stockpile for small mammals, who also have trouble getting official government ID cards for border crossings so they are usually illegal immigrants.

The second report is of the hospitalization of a Belgian man just back from China where he visited rural areas and food markets. Upon return March 5 he developed fever and headache and was hospitalized in Brussels in an abundance of caution. As the Belgian authorities point out, this is a possible case and not a probable or confirmed one. My guess is it will turn out to be something else. But it shows how easily this virus can move around on apparently healthy people given the speed of travel today. The thought that an antiviral campaign would seal off an area in a way to prevent this is unrealistic (I am being kind here). And there is nothing to say that there wouldn't be multiple and sometimes hidden outbreaks.

Time to give up the idea we can stop this pandemic in its tracks and time to set about preparing for the consequences in earnest and without distractions.