Influenza Epidemic

Epidemic usually refers to an occurrence of a disease in large number within a specified community. Influenza can be destructive as the flu virus was responsible for the worst flu epidemic to strike the world since the plague epidemics of the middle ages. The influenza epidemic of 1918-1919 caused the deaths of 20 million people, more than those who died in all the battles of World War I.

The flu virus initially infects epithelial cells in the upper respiratory tract. This has the two-fold effect of causing desquamation of the ciliated epithelium and loss of the protective muco-ciliary escalator. It also results in a non-productive cough. In addition, viral replication causes interferon induction and this causes the array of symptoms that define flu-like symptoms, i.e., fever, headache, chills, malaise and myalgia. Influenza characteristically has an abrupt onset. The upper respiratory illness lasts for approximately a week unless a secondary bacterial infection occurs leading to bronchitis or pneumonia or the influenza virus itself invades the lower respiratory tract.

Influenza belongs to a family of viruses called Orthomyxoviridae. Three genotypes of influenza virus exist, namely influenza A, influenza B, and influenza C. Type A is associated with epidemics and has many mammalian hosts. Type B infects only humans and causes disease but less severe than type A. Type C only infects humans and is thought to be harmless. This strain is genetically and morphologically distinct from the former genotypes.

The most common treatment for influenza is bed rest, plenty of fluids, and aspirin or acetaminophen to relieve fever and discomfort. Antibiotics are not effective against viruses, but they can be used to treat bacterial infection that results from influenza virus. Flu shots and vaccines are an effective means of preventing the disease and apart from these, the antiviral drugs such as Tamiflu, Relenza, amantadine, rimantadine and Peramivir provides relief in case of flu.