11.   Normally, a bird virus has to go through an intermediate body, or host, such as a pig, to become infectious to humans.

12.   Officials constantly keep track of influenza developments because the virus has a nasty habit of changing its basic characteristics.

13.   Past viruses had hokey and unconvincing headers.

14.   Previous macro viruses had to wait for an unwitting human to pass them on via e-mail.

15.   Symptoms may come on fastest when the bite is close to the head, because then the virus has a shorter trip up nerve fibers to the brain.

16.   The AIDS virus has unique and devilish tricks that make it so deadly.

17.   The difference is this virus has a somewhat warped sense of humor.

18.   The harm is the Anna virus has the capacity to overload e-mail servers.

19.   The mousepox virus has no affinity for people and poses no threat to humans.