Influenza (Flu)

What is Influenza?

Influenza, more commonly known as the flu, is a viral infection of airways affecting the lungs, throat and nose. There are two main types of Influenza strains called Influenza A and B. Contrary to popular belief, Influenza is completely different than the “stomach flu” categorized with symptoms of nausea, diarrhea and vomiting.

Influenza is considered to be one of the most common illnesses people deal with. It is considered to be very contagious. In high-risk groups, Influenza can be deadly.

Most at risk

  • Residents of nursing homes or long-term care facilities
  • People over the age of 65
  • People with weakened immune systems
  • People who have certain medical conditions such as kidney disease, cancer and diabetes.


What are the Symptoms of Influenza?

People may become mildly ill while others might experience more severe symptoms.

Symptoms include

  • Cough
  • fatigue
  • high fever
  • sore and swollen throat
  • muscle and body aches
  • headaches
  • sudden cold chills
  • varying loss of appetite
  • nasal congestion

Seek medical attention

People who are experiencing more severe symptoms such as the following should see their doctor immediately.

Severe symptoms include

  • rapid breathing
  • chest pains
  • shortness of breath
  • bloody or colored mucous in your saliva
  • confusion or dizziness
  • blue or grey skin color
  • severe or ongoing vomiting

Influenza Causes

Influenza is caused by exposure to an influenza virus. There are hundreds of strains of the influenza virus, and they’re classified into four categories, named ‘A’ through ‘D’. Strains from category ‘A’ are the most genetically diverse, and have been responsible for all known influenza pandemics. Category ‘A’ influenza strains reproduce relatively quickly, and can sometimes be transmitted between different mammals and birds, resulting in sometimes very contagious and resilient viruses. Category ‘B’ and ‘C’ strains are less common and usually not as severe, and category ‘D’ strains do not infect humans.

The influenza virus can be transmitted in three ways:

  • Directly, if an infected person’s mucus or saliva lands directly in someone’s mouth, nose, or eyes
  • Airborne, if someone inhales particles of mucus or saliva that remain airborne after a cough or sneeze
  • Surfaces, if someone touches a surface covered with infected mucus or saliva particles

Depending on the temperature, humidity, and surface it lands on, many strains of the influenza virus can survive outside the body for up to several weeks.

How is Influenza Treated?

Influenza usually can be resolved without treatment.

Treatments include

A person will usually be told to rest, consume plenty of fluids and take any over-the-counter medication for aches and pains such as acetaminophen (Tylenol), Ibuprofen (Advil) or Naproxen (Aleve). A person who is in a high-risk category may be prescribed antibiotics.

The majority of healthcare professionals will advise patients that an annual Influenza vaccination (flu shot) will assist in prevention of getting Influenza. See your healthcare practitioner about getting a flu shot.

Influenza Prevention

The most effective way to prevent most strains of influenza is to receive an annual vaccination. Vaccinations prepare the immune system to effectively fight off any later influenza infection. Vaccinations are especially recommended for those at higher risk: children and the elderly, those with compromised immune systems, and those who live in close quarters, such as dormitories.

Good hygiene can also effectively prevent a lot of influenza infections. The virus is killed by soap and most sanitizers, so frequently washing one’s hands during flu season (autumn and winter) can often thwart possible infections.

It’s critically important for those infected with influenza to simply avoid others while they recover. A major preventable cause of infection is “presenteeism,” or working while sick. Employees or students who continue to work alongside their peers while sick with influenza put those around them at an unfair risk; managers ought to discourage this for the sake of their team’s health and productivity.

Last Reviewed:
September 14, 2016
Last Updated:
February 08, 2018