Flu is caused by a virus that belongs to the influenza A group. Influenza is an airborne infection of the respiratory system that is found on every continent and can infect individuals of every age group. Its most common symptoms are fever, headache, cough, infection of the sinuses and general fatigue. In severe cases, pneumonia is also possible, and influenza has been known to have fatal outcomes.
Virus
The influenza family of viruses has three subtypes that cause disease in humans. Influenza A, B and C all have been known to infect humans. Viruses that belong to the subtype influenza A are the most likely cause of epidemic outbreaks of the disease. Influenza B causes epidemic outbreaks less frequently than type A. Type C flu is the cause of sporadic infections, it rarely causes an outbreak of more than a few individuals. A flu outbreak is usually caused by a new strain of the influenza virus. New strains usually infect humans after contact with infected animals. The last two dangerous strains have been traced back to an animal reservoir. The H5N1 strain of flu was contracted from the bird populations of Southeast Asia. The H1N1 strain has been traced to Mexican swine.
Transmission
An infected individual has the potential to infect many others with the influenza virus. When an infected individual breathes, sneezes, coughs or speaks, he is excreting the influenza virus into the air, leaving people in the vicinity at risk for infection. A person becomes infected with influenza after the virus comes into contact with her mucous membranes. Your eyes, the inside of your mouth, respiratory tract and nasal canals are all covered with mucous membrane.
Disease
After the virus enters a person's system, it causes clinical symptoms in one to three days. The disease usually resolves itself fully in a week without treatment. The disease causes an array of symptoms, such as fever, headache, muscular pain and fatigue. An infected individual is most likely to infect people around them when their symptoms are most severe. When the disease is the most severe, the concentration of the virus in the body is at its highest. The amount of the virus excreted is also highest when the symptoms are most severe.
Infection Control
Controlling infection is done by finding and treating infected individuals, preventing susceptible individuals from coming into contact with infected individuals and increasing the immunity of susceptible individuals. During a flu epidemic, it is best for susceptible individuals to avoid poorly ventilated and crowded areas, such as theaters and concert halls. These areas increase the risks of infection considerably.
Increasing immunity is done by vaccinating individuals at risk for infection.
Treatment
During flu outbreaks, individuals are treated not only to alleviate their symptoms but also to lower the risk of transmission. Non-steroidal anti-inflammatory drugs are used to alleviate symptoms, and anti-viral medication is used to lower the concentration of the virus. Lowering the concentration of the virus in a patient's body slows the progress of the disease, speeds recovery and lowers the risk of infecting others.
References
- "Control of Communicable Diseases Manual 18th Edition"; David L. Heymann; 2004
- "Harrison's Principles of Internal Medicine 16th Edition"; Lawrence Madoff, James Macguire, Kenneth Brandt, Bruce Gillaind, Scott Thaier; 2005
- CDC: Influenza
- "Preventive and Social Medicine"; K. Park; 1995
- "Epidemiology"; Armen Z. Hambartsumyan; 2002
