Health Topic Categories

- Infections -

August 2nd, 2018


Seasonal Flu

What Is Flu?

Influenza, or “flu,” is a highly contagious respiratory illness that occurs in seasonal epidemics.  An episode of flu typically runs its course over several days.  Although usually just a severe nuisance, flu can sometimes result in respiratory failure and death.

 

Symptoms

An attack of influenza is usually accompanied by muscle aches, headache, fever, sore throat, red watery eyes, runny nose, and cough.  Only some of the symptoms may be present.

 

These symptoms sound like a cold, and like a cold, flu is a respiratory infection. However, influenza is caused by a different virus and is more severe.

 

Severity

Each year about 200,000 Americans are hospitalized because of flu complications. The number of deaths varies depending on the annual virus strain; but American deaths have recently ranged from 3,000 to 49,000 in a year.  While human lives are most important, it is noteworthy that even mild strains of the flu can impact the American economy by $10 billion annually in lost productivity.

 

Contagion

Influenza is typically spread by the aerosol droplets propelled in the course of a cough or sneeze.  Even people six feet from a sneeze are at increased risk of infection from these micro particles.  

 

Flu can also be spread from surfaces.  If a person coughs into their hand or sneezes into a handkerchief and then touches an object such as a doorknob or computer keyboard, that object becomes contaminated. A person who touches the object shortly afterward can be infected, usually when they transfer the virus from their hand to a mucous membrane such as the nose, mouth, or eye.

 

Because of the high level of contagion, it is important that flu patients remain home to avoid infecting co-workers.

 

Infectivity

Once a person becomes infected by the virus, it takes 1 to 4 days before they exhibit symptoms.  However, they may transmit the virus to others even before symptoms become evident. Thus it is not sufficient to avoid persons who appear to be sick.  It is important to make a habit of frequent hand washing as this can reduce both virus dissemination and acquisition.

 

Complications

Occasionally influenza does not run its normally uneventful course but instead results in complications.  Some of the most serious of these are viral pneumonia, bacterial pneumonia, respiratory failure, an inflammation of the heart (myocarditis), an inflammation of the membrane surrounding the heart (pericarditis), and multiorgan failure.

 

Vulnerability

Fatalities are most common in infants and the elderly. Thus it is important that senior citizens receive vaccination, the “flu shot.”  Vaccination is also important for pregnant women.  Pregnant females are not at risk from the flu shot and they need vaccination because they are at increased risk of complications from flu and they need to pass on their immunity to the newborn.

Others who are at increased vulnerability are those who are immunocompromised from disease or chemotherapy.

 

Pandemics

A pandemic is an epidemic that occurs over a broad area.  Four flu pandemics have occurred in the last century.  These epidemics occurred when a highly contagious and aggressive strain of the virus emerged.  

 

The infamous “Spanish flu” of 1918 killed nearly 675,000 people in the US and a possible 50 million people worldwide.  

 

The “Asian flu” of 1957 killed about 69,800 people in the US.  

 

The “Hong Kong flu” of 1968 took the lives of 33,800 people in the US.  The relatively modest number may have been largely due to the availability of antibiotics to treat secondary bacterial infections.  

 

The “swine flu” of 2009 caused between 9,000 and 18,000 deaths.  The reduced number of deaths in this epidemic may have been due to the fact that 80 million people were vaccinated.

 

Flu Vaccination Does Not Cause Flu

Vaccination against flu can be by injection or nasal spray.  The injection contains virus that is inactivated (“killed”). The nasal spray contains virus that is attenuated (“weakened”) and so altered that it can be active only at the cooler temperatures of the nose and not in the warmer temperatures of the lungs. The result is that flu vaccination does not cause the flu!

 

Vaccination Side Effects

Serious vaccination side effects are quite rare.  They are circumvented by avoiding certain flu vaccinations in specific groups of people.

 

Traditionally, flu vaccine was produced using chicken eggs and was contraindicated in persons with egg allergy.  Since 2012 a vaccine prepared in a different manner has been available for persons 18 years of age and older who are allergic to eggs.

 

An inactivated virus vaccination rather than an attenuated virus vaccination is generally appropriate for persons with weakened immune systems congenitally, from illness, or from chemotherapy.

 

In short, some type of flu vaccination should be appropriate for most individuals 6 months of age and older.

 

So If I Get Vaccinated, I Can’t Get the Flu, Right?

Not quite!  In the recent past flu vaccination has had 70% effectiveness against influenza B and 60% effectiveness against influenza A.  This is so because:

  • The US Center for Disease Control (CDC) must project in advance the virus strains of the upcoming flu season.
  • Different individuals have different capabilities of manufacturing antibodies in response to the stimulus of the vaccine.
  • It takes 1-4 days after infection for flu symptoms to emerge.  Persons can be infected before they receive the vaccination.
  • It requires 7-14 days for the body to build antibodies from the stimulus of the vaccination. Vaccinated people can be infected with flu during this time period.
  • Symptoms of flu can be simulated by other virus infections.  Flu vaccinated persons who seem to get the flu may have these other infections.

 

How Can I Prevent the Flu?

The best method of dealing with the flu is not to have it!  In order to greatly reduce chances of getting the flu, it is most important to take these precautions:

  • Practice frequent hand washing, especially after contact with objects touched by infected persons or the general public.
  • Avoid proximity to infected persons.
  • If infected, stay home and avoid contact with others. Bear in mind that you are infectious for 4-9 days after onset of symptoms.
  • Finally, present yourself for vaccination.  This is your surest way of protecting yourself from flu.  As an added benefit, remember that by getting vaccinated, you are also protecting newborns, elderly, chemotherapy patients, and others unable to fully benefit from their own vaccination.

 

Conclusion

So please stay well this season and protect yourself from flu.

 

Thomas Falasca, DO

View this fact-filled video on flu symptoms from the US Centers for Disease Control!

 

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