Nevertheless, the epidemic is proving less contagious and lethal than other seasonal influenza epidemics in recent years, and does not appear likely to have a significant economic cost.

It is not clear whether this represents a different philosophy or a response to a different kind of pandemic that is expected to be less lethal than avian flu," he said.

As the nature of warfare changes, favoring urban combat and regional conflicts rather than conventional combat, the military is gaining a great deal of interest in less-lethal weapons.