Cold and Flu
A-B-C, 1-2-3: Type of Flu and Me
A-B-C, 1-2-3: Type of Flu and Me
Fever, cough, sore throat, and chills—these are all common symptoms of the flu (influenza). According to the National Institute of Allergy and Infectious Diseases, up to 20 percent of Americans suffer from such symptoms every flu season. Although patients often say they have the flu, there are actually several viruses that can cause the respiratory illness. On top of that, some forms of the flu are more severe than others because of a lack of prevalence and subsequent available treatments. Understanding the different types of flu can potentially save your life.
Understanding the Flu A-B-C’s
Flu viruses are literally classified by ABC’s. Influenza A and B are the most common types of viruses. These strains not only cause the annual seasonal flu, they are also responsible for occasional pandemics linked to new strains. A viruses are classified by subtypes based on differences in surface proteins. Unlike B viruses, the A strains can occur in both animals and humans.
Influenza C is not as common as A and B strains, and it isn’t related to the seasonal flu. The annual flu vaccine doesn’t offer protection against C viruses.
Evolution of a Flu Virus
In addition to flu classifications, it’s also important to understand how new viruses form. Each type of flu is based on genetic changes. This explains how some viruses can start in animals and eventually make their way into the human population. Most flu viruses start in birds, and then make their way to pigs before affecting humans.
Seasonal Flu Viruses
Seasonal flu viruses stem from A and B influenza. Such strains are responsible for the miserable flu symptoms many Americans experience every fall and winter, including:
- fever and chills
- body aches and sore throat
- cough and wheezing
- excessive fatigue
Symptoms typically last for one to two weeks, unless other complications develop.
Seasonal flu viruses are highly contagious and mostly spread through small droplets in the air from infected persons.
Swine Flu (H1N1)
Technically known as H1N1, the swine flu was a new strain of virus to humans in 2009. It was dubbed the “swine flu” because this virus was originally exclusive to pigs. Symptoms of H1N1 are the same as the seasonal flu, which can cause difficulties during diagnosis. The virus caused a pandemic between 2009 and 2010 because there was no human immunity to it. Since then, every seasonal flu shot offers protection against H1N1.
Avian Influenza Viruses
More commonly known as the “bird flu,” the avian influenza virus is an A virus that starts in birds. One example is the H5N1 strain, which has caused numerous poultry deaths in the Middle East and Asia over the last decade. Flu.gov reports that this same strain is also responsible for at least 600 human deaths. This strain is believed to have been transmitted between birds and poultry to humans, but not between people.
H7N9 is another form of avian flu virus. According to Flu.gov, no cases of H7N9 outside of China have been found in birds or humans in the U.S. Still, given the way flu viruses transform, you shouldn’t ignore the avian flu just yet. This flu has caused severe respiratory infections and related deaths in China.
The term “pandemic” is a frightening one, and for good reason. Flu pandemics are related to influenza A viruses that are just introduced to the human population. While flu shots may offer immunity to known virus strains, they can’t protect against new ones. This lack of protection leaves humans vulnerable. The most recent occurrence of a flu pandemic was the swine flu in 2009.
Despite the severity of pandemics, Flu.gov says they are a rare occurrence. Flu.gov estimates a total of three pandemics during the 20th century. The best way to protect yourself during a pandemic is to limit travel and practice good hygiene habits.
Scientists and health professionals both rely on the influenza classification process to name and diagnose new strains of the flu. However, flu viruses constantly change. This phenomenon is referred to as an antigenic drift. New viruses form over time, which is why the annual influenza shot contains different strains from year to year. Some types of influenza, such as the avian flu, may become dormant and then reappear years later. No matter what types of viruses are out there, you can help protect yourself by practicing safe hygiene and getting the annual flu shot.
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- About the Flu. (n.d.). Flu.gov. Retrieved October 12, 2013, from http://www.flu.gov/about_the_flu/index.html#
- Avian Influenza A (H7N9) Virus. (n.d.). Flu.gov. Retrieved November 7, 2013, from http://www.flu.gov/about_the_flu/h7n9/index.html
- H5N1 Avian Flu (H5N1 Bird Flu). (n.d.). Flu.gov. Retrieved November 7, 2013, from http://www.flu.gov/about_the_flu/h5n1/index.html
- The Flu Types. (2011, August 8). National Institute of Allergy and Infectious Diseases. Retrieved October 12, 2013, from http://www.niaid.nih.gov/topics/flu/understandingflu/pages/definitionsoverview.aspx