The Politics of Disease

The language of epidemiology, the study and prevention of the spread of infectious diseases, is steeped in the metaphor of blockade. Doctors and scientists develop "barrier" nursing techniques and try to erect "ring fences" within society to corral a dangerous microbe, preventing it from jumping between people and countries. But one of the lessons learned by Hong Kong, the city hit hardest by the deadly epidemic of Severe Acute Respiratory Syndrome (SARS), is that it does no good to slam the ring-fence gate after the killer has left the pen.

Prompt action by local health authorities can nip...