The World Health Organization (WHO) has estimated that worldwide approximately 5-10% of all respiratory infections are caused by Influenza. Annually, 3-5 million people also go on to develop a severe illness caused by Influenza.
Influenza is transmitted primarily through person-to-person contact with droplets traveling up to 6 feet away. Transmission can also occur through contact with contaminated surfaces and then touching a mucosal surface such as the nose, mouth, or eyes. It is thought that people may be able to transmit the virus up to a day or two before showing symptoms and up to 5-7 days after the start of illness. Symptoms related to Influenza may include fever and or chills, runny nose or congestion, head and body aches, and general fatigue.
The Influenza virus is an enveloped, negative-sense RNA virus in the Orthomyxovirus family. The virus is generally 80-120 nanometers (nm) in diameter. There are three human subtypes (A, B, C). These types are determined by the internal structure proteins. Types A and B are seasonal or pandemic, whereas type C tends to be a mild respiratory illness.
Type A is divided into subtypes and strains based on the two surface "spikes" of glycoproteins. H or HA (Hemagglutinin) with 18 known subtypes, and N or NA (Neuraminidase) with 11 known subtypes. This combination creates the strains (ie. H1N1, also known as swine flu, and H5N1, known as the avian flu). In addition to the glycoproteins, there are also M2 ionic channels along with matrix protein (M1) located just under the outer lipid layer. This M1 protein makes up 40% of the viral protein.
1. Higgins, Dan. "This is a 3-dimensional illustration highlighting the different features exhibited by an influenza virus, including the surface proteins, hemagglutinin (HA) and neuraminidase (NA)." CDC.gov, 2014, https://phil.cdc.gov/Details.aspx?pid=17346
