Types Of Influenza
There are four major types of influenza viruses, i.e., A, B, C, and D. The influenza A and B human viruses are responsible for causing the seasonal outbreak of diseases commonly known as the flu season. The influenza outbreak usually happens at the beginning of the winter season and affects the majority of people. The classification of different influenza virus strains depends on surface proteins such as neuraminidase (N) and hemagglutinin (H). There are almost 11 various NA subtypes and 18 various HA subtype, which causes influenza infection. Following is the detail of the four major types of influenza viruses:
Influenza virus A
Influenza virus A is the major cause of flu pandemics globally, and a pandemic appears when the strains of old and new virus strains of influenza. The ability of influenza virus A to spread is quite efficient and results in causing a pandemic. The influenza virus A further distinguishes into subtypes that we attain by the presence or absence of protein on the virus’s surface. Recent studies suggest that there are almost 198 various combinations of subtype influenza virus A. The most common subtypes which spread most efficiently among the individuals are A(H3N2) and A(H1N1). The categorization of influenza virus A reaches further towards clades and sub-clades. The clades and sub-clades depict the proportion of viruses among the community and help prevent an outbreak of flu.
Influenza virus B
Influenza virus B also results in the most commonly spreading flu among the community. There is no further categorization of influenza virus B into subtypes, but there is a division of influenza virus B into two lineages. The antigenic and genetic properties of influenza virus B change much more slowly than influenza virus B. The two lineages of influenza virus B are B/Victoria and B/Yamagata. The recent data on influenza surveillance reveals that the circulation of influenza virus B changes according to the geographical location. Both lineages are increasing in circulation all over the world.
Influenza virus C
Influenza virus C generally causes mild symptoms and is not responsible for the epidemics. The frequency of influenza virus C is a lot less and does not interest public health importance.
Influenza virus D
The influenza virus D usually affects cattle, and the studies show zero evidence of influenza virus D to cause illness or to infect the human population.