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The influenza virus is the second most common respiratory illness in the world, next to the common cold, according to 2005 information from Florida State University, with an estimate that 25 to 50 million Americans contract the flu each year 1. Highly contagious and most prevalent during the winter, the flu may present with muscle aches and pains, sore throat, fatigue, dry cough and runny nose, and in extreme cases, may lead to death. The influenza pathogen consists of three types.
If you are experiencing serious medical symptoms, seek emergency treatment immediately.
Twenty-five different subtypes of type A influenza exist, notes the Centers for Disease Control and Prevention 2. The type A influenza pathogen has the ability to change its viral makeup. This process is fast and is called antigenic shift. There may be several major changes during the same flu season. The CDC notes that in 2009, a major shift produced the H1N1 influenza pandemic.
- Twenty-five different subtypes of type A influenza exist, notes the Centers for Disease Control and Prevention 2.
- The type A influenza pathogen has the ability to change its viral makeup.
About Type B Strain Flu
The type B influenza pathogen does not change as swiftly as the type A virus, making it easy to monitor. The CDC describes the process as antigenic drift, which produces smaller changes in the viral makeup over a longer period of time. Vaccines are constantly being updated to stay current with the pathogen's ability to change.
Type C influenza virus is different from type A and type B virus, genetically and morphologically, according to the Florida State University 1. Because of the resulting mild symptoms, type C is thought to be of little medical threat.
About Type B Strain Flu
Differences Between Influenza A and B
What Is the Incubation Period for the Flu?
Sweating, Chills, Fatigue & Nausea Symptoms
Symptoms of Type A Influenza
Drugs That Cause Peripheral Neuropathy
The Different Stages of a Common Cold
Common Human Viruses List
The After-Effects of the Flu
What Is the Difference Between Influenza A & B?
- Florida State University: Molecular Expressions: The Influenza Virus
- Centers for Disease Control and Prevention: How the Flu Virus Can Change: "Drift" and "Shift"
- Ghebrehewet S, MacPherson P, Ho A. Influenza. BMJ. 2016;355:i6258. doi:10.1136/bmj.i6258
- Centers for Disease Control and Prevention. Influenza (flu): Types of influenza viruses. Updated November 18, 2019.
- Nakatsu S, Murakami S, Shindo K, et al. Influenza C and D viruses package eight organized ribonucleoprotein complexes. J Virol. 2018;92(6):e02084-17. doi:10.1128/JVI.02084-17
- Bourret V, Lyall J, Frost SDW, et al. Adaptation of avian influenza virus to a swine host. Virus Evol. 2017;3(1):vex007. doi:10.1093/ve/vex007
- Anhlan D, Grundmann N, Makalowski W, Ludwig S, Scholtissek C. Origin of the 1918 pandemic H1N1 influenza A virus as studied by codon usage patterns and phylogenetic analysis. RNA. 2011;17(1):64-73. doi:10.1261/rna.2395211
- World Health Organization. Influenza: FAQs: H5N1 influenza. Updated April 2011.
- Lai S, Qin Y, Cowling BJ, et al. Global epidemiology of avian influenza A H5N1 virus infection in humans, 1997-2015: a systematic review of individual case data. Lancet Infect Dis. 2016;16(7):e108-e118. doi:10.1016/S1473-3099(16)00153-5
- Centers for Disease Control and Preventions. Influenza (flu): Key facts about flu vaccines. Updated April 28, 2020.
- Centers for Disease Control and Prevention. Influenza (flu): Who should & who should NOT get vaccinated. Updated October 11, 2019.
- Asha K, Kumar B. Emerging influenza D virus threat: What we know so far! J Clin Med. 2019;8(2):192. Published 2019 Feb 5. doi:10.3390/jcm8020192
Carrie Cross has been writing for profit and pleasure for more than 35 years. Her background includes business, real estate, entrepreneurship, management, health and nutrition. A registered nurse, she has published various pieces, including web content, numerous newspaper and magazine articles and columns and six books.