Prevention and Treatment of Viral Infections

Free Response

Why is immunization after being bitten by a rabid animal so effective and why aren’t people vaccinated for rabies like dogs and cats are?


Rabies vaccine works after a bite because it takes a week for the virus to travel from the site of the bite to the central nervous system, where the most severe symptoms of the disease occur. Adults are not routinely vaccinated for rabies for two reasons: first, because the routine vaccination of domestic animals makes it unlikely that humans will contract rabies from an animal bite; second, if one is bitten by a wild animal or a domestic animal that one cannot confirm has been immunized, there is still time to give the vaccine and avoid the often fatal consequences of the disease.

The vaccine Gardasil that targets human papilloma virus (HPV), the etiological agent of genital warts, was developed after the anti-HPV medication podofilox. Why would doctors still want a vaccine created after anti-viral medications were available?


Anti-viral medications treat HPV after the skin of the genitals has been infected. Conversely, Gardasil stimulates the immune system to prevent infection of the tissue, even if a person is exposed to HPV. Since HPV is often asymptomatic, particularly in men, the vaccine also controls the spread of disease (patients will not seek treatment for a disease if they do not realize they are infected).