EVERYDAY SCIENCE

Detailed explanation-1: -There are four types of influenza viruses: A, B, C, and D. Influenza A and B viruses cause seasonal epidemics of disease in people (known as flu season) almost every winter in the United States. Influenza A viruses are the only influenza viruses known to cause flu pandemics (i.e., global epidemics of flu disease).

Detailed explanation-2: -influenza, also called flu or grippe, an acute viral infection of the upper or lower respiratory tract that is marked by fever, chills, and a generalized feeling of weakness and pain in the muscles, together with varying degrees of soreness in the head and abdomen.

Detailed explanation-3: -All influenza viruses consist of single-stranded RNA as opposed to dual-stranded DNA. The RNA genes of influenza viruses are made up of chains of nucleotides that are bonded together and coded by the letters A, C, G and U, which stand for adenine, cytosine, guanine, and uracil, respectively.

Detailed explanation-4: -Influenza is an infectious viral illness. The name “influenza” originated in 15th century Italy, from an epidemic attributed to “influence of the stars.” The first documented pandemic, or worldwide epidemic, that clearly fits the description of influenza was in 1580.