In 1997 a virulent strain appeared, able to infect the human nervous system.

The cercariae are very particular over where they develop, needing small, forested areas with streams to infect their human host.

Further the metacestodes recovered from infected liver were used to infect a human volunteer, whom they had given two years earlier.

Any mammal infected with rabies may behave unexpectedly, even aggressively, and could infect a human with rabies by biting.

The weaponized agent must be resistant to degradation by rain and ultraviolet radiation from sunlight, while retaining the ability to efficiently infect the human lung.