After an incubation period of one to four days, a bout of influenza typically resolves after three to seven days. 

Each flu season, however, claims its victims, and for those of us who recover it seems unbelievable that something seemingly no worse than a bad cold can actually be a killer.

Influenza is a highly contagious viral illness that occurs predominantly in the winter months. Similar to the common cold, flu affects the respiratory tract, but symptoms tend to be more severe.

Two weeks max

According to the Harvard Special Report Viruses and Disease, the flu is caused by one of three different virus types: influenza A, B or C. It spreads rapidly through airborne droplets of saliva, personal contact and by sharing utensils or items like clothing and other personal effects.  

Although you’ll probably feel a lot better after a week, you might be stuck with a lingering cough and general malaise for approximately another week.

Four ways the flu can kill you

The following are four examples of conditions that can turn a run of the mill bout of flu into a killer:

1. A weak immune system

Both the very young and old have weaker immune systems. Infants and young children have not yet built up an effective immune system, and in the case of senior citizens immunity may not be as strong as it used to be. 

This doesn’t mean that people in their thirties don’t die from the flu. A hundred years ago, for example, the Spanish flu killed indiscriminately.

In 2008, researchers discovered what made the 1918 flu so deadly: The virus was able to weaken victims’ bronchial tubes and lungs, which led to bacterial pneumonia (secondary infection).

According to Centers for Disease Control and Prevention (CDC), people with HIV and Aids are at high risk for influenza-related complications because of a weakened immune system.

Other factors that can weaken your immunity are:

• Lack of sleep
• Chronic stress
• Poor hygiene
• Insufficient exercise
• Poor nutrition
• Smoking and drinking
• Excessive use of antibiotics

2. Respiratory failure

The influenza virus causes infection of the upper respiratory tract (nasal passages, throat) and lower respiratory tract (lungs). This leads to inflammation, an immune reaction that causes swelling in these organs.

When lung tissue becomes swollen with immune cells, it becomes harder or impossible for oxygen to reach the blood vessels. This is called respiratory failure, which is one of the most common and fastest ways the flu can kill you. Death can occur quickly and with little warning.

3. Sepsis

Infection of the respiratory tract caused by the flu virus can trigger an inflammatory response, not only in the lungs, but in the entire body.

Like inflammation in the lungs, the rest of your organs may also develop severe swelling as part of the immune reaction. This triggers sepsis, which is when the inflammation overwhelms your organs, causing multiple shutdown and rapid death.

4. A secondary infection

When your immune system is struggling with a viral infection, other bacteria that are present in the body, but are normally under control, can attack the lungs and cause a secondary infection. This is called pneumonia. Secondary pneumonia can develop slowly as the bacteria multiply inside your lungs and overwhelm your exhausted immune system.

Antibiotics may help, but may not be able to kill the bacteria fast enough. If anyone with influenza suddenly appears to take a turn for the worse, it might be pneumonia, in which case one needs to get medical help as soon as possible. 

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Eugene Lotter