Flu explained

Influenza, which is often abbreviated to 'fluA viral infection affecting the respiratory system.', is an infectionInvasion by organisms that may be harmful, for example bacteria or parasites. of the respiratory system by one of a number of influenzaA viral infection affecting the respiratory system. virusesMicrobes that are only able to multiply within living cells..

Flu is among the most common causes of respiratory infections in human beings.[1] It is believed that there have been outbreaks of fluA viral infection affecting the respiratory system. since at least the Middle Ages, and possibly even since ancient times.[2]

Flu virusesMicrobes that are only able to multiply within living cells. infect the cells of the upper (mouth and throat) and lower respiratory tractThe parts of the body that are involved in respiration. The respiratory tract includes the nasal passages, throat (pharynx), windpipe (trachea), bronchi and lungs. (the lungs). Very rarely the infectionInvasion by organisms that may be harmful, for example bacteria or parasites. may spread to the bloodstream.[3]

How badly a fluA viral infection affecting the respiratory system. infectionInvasion by organisms that may be harmful, for example bacteria or parasites. affects a person depends very much on the individual. For example, healthy young adults may have a debilitating illness with a high fever lasting one to two weeks but usually without serious consequences. Older people, however, or those with chronicA disease of long duration generally involving slow changes. conditions such as cardiovascular disease, may experience a much more serious infectionInvasion by organisms that may be harmful, for example bacteria or parasites., sometimes with complications such as pneumoniaInflammation of one or both lungs..[4]

Flu is a major public health problem.[3] Indeed, influenzaA viral infection affecting the respiratory system. virusesMicrobes that are only able to multiply within living cells. are the only respiratory virusesMicrobes that are only able to multiply within living cells. to cause increases in the number of adult deaths in the winter months, in temperate climates at least.[5]

Other infections that cause an illness similar to fluA viral infection affecting the respiratory system. include parainfluenza virusesMicrobes that are only able to multiply within living cells., respiratory syncytial virusesMicrobes that are only able to multiply within living cells., and Mycoplasma pneumoniaInflammation of one or both lungs. bacteriaA group of organisms too small to be seen with the naked eye, which are usually made up of just a single cell..[2]

References: 
  1. Hampson AW and Mackenzie JS. The influenzaA viral infection affecting the respiratory system. virusesMicrobes that are only able to multiply within living cells.. MJA. 2006;185(10 Suppl):S39-43.
  2. Taubenberger JK and Morens DM. The pathology of influenzaA viral infection affecting the respiratory system. virusA microbe that is only able to multiply within living cells. infections. Annu Rev Pathol. 2008;3:499-522.
  3. Stiver G. The treatment of influenzaA viral infection affecting the respiratory system. with antiviralA substance that acts against viruses, for example and antiviral drug. drugs. CMAJ. 2003;168:49-57.
  4. Zambon MC. Epidemiology and pathogenesis of influenzaA viral infection affecting the respiratory system.. Journal of Antimicrobial Chemotherapy. 1999;44:3-9.
  5. Newton DW, Treanor JJ and Menegus MA. Clinical and laboratory diagnosisThe process of determining which condition a patient may have. of influenzaA viral infection affecting the respiratory system. virusA microbe that is only able to multiply within living cells. infections. Am J Managed Care. 2000;6(suppl):S265-75.