June 09, 2003

Monkey Pox

A number of Midwestern states have reported cases of monkey pox. Apparently these are the first cases of this disease to be reported in the western hemisphere. Fortunately, while monkey pox symptoms are similar to small pox, it is not as virulent and mortality in generally healthy populations is likely to be low.

I have written some on SARS and how it appears that that virus may have jumped from domestic animals to humans. The same appears to be true of monkey pox, but rather than pigs and chickens, the animals are Gambian rats and prairie dogs. The path appears to be from Gambian rat to prairie dog to human. Monkey pox makes the prairie dogs sick and can be fatal to those animals As reported by the AP it may be that most of the cases in the midwest can be traced back to a single exotic pet distributor in Chicago. That shop has been quarantined and many of its prairie dogs have been killed.

This brings to mind a number of thoughts. The first of which is "What in world are people thinking with respect to pets!?" Now I may be a bit curmudgeonly on this front, but I don't think that I am out of line thinking that it doesn't make a lot of sense to bring large African and Texan rodents together in close quarters and then to add a large primate to the mix.

Joel Cohen and his collegues figured out that huge decreases in Chagas disease could be achieved by having the livestock live outside and the humans live inside. While this seems obvious in the case of the rural Andes, it does not seem to be applied to suburban Chicago.

Two other things that come to mind are: 1) the seeming prevalence of disease that jumps from animals to humans; and 2) the global mixing of species. Quick surveys of the web suggest that monkey pox, here-to-fore, has been confined to central Africa. Now it has jumped directly to the metropolitan Midwest. There seems to be no question that the disease was transported by exotic pet traders from Africa to the US. I don't know whether to be amazed that our livestock controls have worked so well for so long or to be horrified at the thought of the geographically artificial inter-species mixing that is going on.

It is likely that this little outbreak will be controlled (provided people don't start turning their sick prairie dogs out into the wild where they can / will infect healthy indigenous populations). And it is in many ways a simple and relatively benign case of human foible and ecentricity. It does, none-the-less, illustrate the kind of thing that we need to manage as we go forward. In this case there are many regulations that control the flow of animals across borders and across ecological niches. That regulatory framework may need to be shored up, but it is one way to approach the problem.

But what happens when something slips through the regulatory net, as appears to have happened with monkey pox; or when the regulatory net is non-existent or inadequate as would be the case with SARS in Guang Dong? When that happens we need another set of mechanisms that are highly dynamic and that can react to a rapidly changing state of affairs. With disease it looks like the strategy is to isolate the disease and then eliminate it; this is the strategy behind quarantine. If a disease gets established in wild populations (as may be the case with SARS and is the fear regarding sick prairie dogs going into the wild) then isolation and eradication will not work and the strategy has to be one of controlling and limiting outbreaks. If we are lucky vaccines can be developed and human morbidity minimized.

Earth systems management is going to have to be able to deal with existing and emerging infectious diseases and the fact that these things will be moved around the globe in strange ways as a function of human weirdness.