a. Definition/Characteristics. Influenza is a highly contagious disease caused
by a virus. The disease spreads by an infected person exhaling the virus, which is then
breathed in by an uninfected person. Once inhaled, the virus comes in contact with
cells of the upper air passages, and new influenza viruses are released in the body.
These viruses infect other cells along the respiratory tract sometimes spreading deep
within the lungs and to other parts of the body. The formerly healthy person exhales
viruses that may be carried away by the air to be inhaled by someone else. Several
different strains of virus including A, B, C, and swine viruses infect people. When the
body produces substances called antibodies, people develop immunity or resistance to
influenza. The antibodies attach themselves to influenza viruses and prevent the
viruses from infecting cells. It is possible for the virus to change its chemical
composition so that the antibodies no longer work. When this happens, the cells of the
body must form new antibodies.
b. Signs/Symptoms. The onset of signs and symptoms is usually sudden and
can include the following:
Slight fever lasting 1 to 7 days (usually 3 to 5 days).
Cough which is nonproductive and dry, occurring in spasms.
Nasal stuffiness and discharge.
Mildly infected throat.
Myalgia (pain in muscles).
Occasional nausea, diarrhea.
c. Complications. These complications can occur:
(1) Necrosis of the respiratory epithelium (tissue death of linings in the
respiratory system) which makes a secondary bacterial infection possible.
The most common complication is pneumococcal pneumonia.
The most serious complication is a staphylococcal infection.