Flu (Seasonal Influenza)

By:    Published: May 10, 2012

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The flu is commonly used to describe seasonal influenza, an illness caused by numerous influenza viruses. This infection affects the respiratory system causing symptoms that can range from mild to life threatening, and is highly contagious. According to the Centers for Disease Control and Prevention, an average of 5 percent to 20 percent of the population within the United States will become infected by the flu each year.

Causes

There are three types of seasonal influenza viruses that can cause infection, which are all RNA virus, but differ in their forms of infection and symptoms:

  • Influenza A: This infection is caused by the influenza virus A and is the most severe type, responsible for many of history's devastating epidemics. The most common hosts are wild aquatic birds. This type of flu can be broken down into multiple subtypes that are named based on the proteins present on the surface of the virus: hemagglutinin (HA) and neuraminidase (NA).
  • Influenza B: This infection is caused by the influenza virus B, which can also cause epidemics, although a pandemic caused by this particular strain has yet to occur. It exclusively infects humans and can be life threatening. It is not classified into subtypes like influenza type A.
  • Influenza C: This infection is caused by the influenza virus C, which usually produces mild symptoms in humans. It has not been linked to an epidemic and is not classified by subtype like type A influenza.

Symptoms

The flu typically begins with a fever of 102 degrees or above that usually lasts for a day or two, but can extend up to five days. You might feel very chill, get body aches and flushed skin. Headache, nausea and even vomiting can occur in some cases.

Symptoms of the flu usually begin within two to three days of exposure to the virus. Because the flu is airborne, it usually spreads to the entire family or community. The flu can cause complications, which can be serious and even life threatening. Common symptoms caused by the flu include:

  • Fever
  • Coughing
  • Sore throat
  • Runny nose
  • Congestion
  • Headaches
  • Body aches
  • Chills
  • Fatigue
  • Loss of appetite

The flu and the common cold can share many symptoms, which is why they are often mistaken for one another. Generally speaking, flu symptoms are a lot worse and more intense than the common cold. Colds are also less likely to cause health complications for individuals suffering from health problems like pneumonia or a weakened immune system.

Complications

Certain individuals are at a high risk of developing health complications that are related to seasonal flu. These individuals include:

  • Children under 5 years old (children under 2 years old have an even greater risk)
  • Adults 65 years of age or older
  • Pregnant women
  • American Indians and Alaskan Natives (According to the CDC)

Individuals suffering from the following health problems are also at a high risk for developing health complications caused by the flu:

  • Chronic lung disease
  • Blood disorders
  • Kidney disorders
  • Liver disorders
  • Endocrine disorders
  • Metabolic disorders
  • Heart disease
  • Neurological and neurodevelopmental conditions
  • Obesity
  • Individuals under the age of 19 who are taking long-term aspirin therapy
  • Anyone suffering from a weakened immune system, like those suffering from cancer, HIV or AIDS

In the event of flu-related complications, hospitalization is required. Flu-related complications include:

  • Pneumonia
  • Bronchitis
  • Sinus infections
  • Ear infections
  • Death

Tests/Diagnosis

One of the most common methods of testing the flu to confirm the influenza virus is by swabbing the nose and throat and investigating for a specific antigen that the body produces to fight influenza. Blood tests can be done to check the severity of the infection. Sometimes, x-rays are done to check for the pneumonic infection of lungs caused by the virus.

Treatment

Unless you are at risk for suffering from flu-related complications, the seasonal flu can be treated with home care:

Those suffering from the flu should drink plenty of fluids and get adequate rest during the infection, and even for a few days after the infection has passed. In instances where it is diagnosed quickly, some antiviral medications can make the illness slightly more short-lived than normal. Most people recover within 10 days without medication.

To help prevent getting the flu, there are flu shots and vaccines available. Flu shots are especially important for anyone who is at risk of suffering from flu-related complications. Healthy individuals should also consider receiving some form of flu vaccination, whether it is a flu shot or nasal spray. Consult your physician for more information about flu vaccinations and whether you should receive one or not.

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