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Unformatted text preview: Influenza - Influenza Virus types A, B, C A - most virulent; responsible for most epidemics, pandemics B - less virulent; causes some epidemics C - least virulent; causes mild infections Virulence: invades m.m., ciliated epithelium of nasal, oropharynx, lungs Transmission: URT secretions - droplet nuclei P/E: nasopharynx Disease: Inc. pd. 1- 3 days. Destroys epithelium inflammation. Symptoms vary with antigenic type. Complications: secondary bacterial infections (pneumococcal pneumonia) Immunity: Active infection produces active immunity, but does not protect against future infections due to frequent antigenic changes in virus: 1) Antigenic drift: due to spontaneous mutations, A &amp; B. 2) Antigenic shift: due to recombination with animal viruses, A only. Vaccine: inactivated viruses (current strains)...
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- Fall '09