What is a Virus?

Viruses are microscopic organisms that exist almost everywhere on earth and can only reproduce within a living organism at a very rapid rate. There is debate as to whether they are “alive.” They can infect animals, plants, fungi, and even bacteria. Sometimes a virusvirus vi·​rus | \ ˈvī-rəs : a disease-causing agent that is too tiny to be seen by the ordinary microscope, that may be a living organism or may be a very special kind of protein molecule, and that can only multiply when inside the cell of an organism   can cause a disease so deadly that it is fatal. Other viral infections trigger no noticeable reaction. A virus may also have one effect on one type of organism, but a different effect on another. This explains how a virus that affects a human may not affect a dog.

Virus Quick Facts:

• Viruses are quasi-living organisms that cannot replicate without a host cell.
• They are considered the most abundant biological entity on the planet.
• Disease causing viruses include: many cold virus types, rabies, herpes, SARSSARS särz : a severe respiratory illness that is caused by a coronavirus (species Severe acute respiratory syndrome-related virus of the genus Betacoronavirus), is transmitted especially by contact with infectious material (such as respiratory droplets or body fluids), and is characterized by fever, headache, body aches, a dry cough, hypoxia, and usually pneumonia — called also severe acute respiratory syndrome   (a coronoavirus but not CoVid 19), HIVHIV ˌāch-ˌī-ˈvē : either of two retroviruses that infect and destroy helper T cells of the immune system causing the marked reduction in their numbers that is diagnostic of AIDS — called also AIDS virus, human immunodeficiency virus  /AIDS, Spanish fluSpanish flu The Spanish flu (also known as the 1918 flu pandemic) was an unusually deadly influenza pandemic. Lasting from January 1918 to December 1920, it infected 500 million people—about a quarter of the world's population at the time. The death toll is estimated to have been anywhere from 17 million to 50 million, and possibly as high as 100 million, making it one of the deadliest pandemics in human history., H1N1, EbolaEbola Ebo·​la | \ ē-ˈbō-lə an infectious and frequently fatal disease marked by fever and severe internal bleeding, spread through contact with infected body fluids by a filovirus ( Ebola virus ), whose normal host species is unknown. Humans may spread the virus to other humans through contact with bodily fluids such as blood. Initial symptoms include fever, headache, muscle pain, and chills. Later, a person may experience internal bleeding resulting in vomiting or coughing blood. Treatment is supportive hospital care., and CoVid 19. MRSAMRSA : any of several strains of a bacterium (Staphylococcus aureus) that are resistant to methicillin and related antibiotics (such as penicillin) and typically live harmlessly on skin and mucous membranes but may cause usually mild infections of the skin or sometimes more severe infections (as of the blood, lungs, or bones) especially in hospitalized or immunocompromised individuals is not a virus. It is a Staphstaphylococcus staph·​y·​lo·​coc·​cus | \ ˌsta-f(ə-)lō-ˈkä-kəs : any of a genus (Staphylococcus) of nonmotile gram-positive spherical bacteria that occur singly, in pairs or tetrads, or in irregular clusters and include causative agents of various diseases (such as skin infections, food poisoning, and endocarditis) bacterium that causes infectioninfection in·​fec·​tion | \ in-ˈfek-shən a : the state produced by the establishment of one or more pathogenic agents (such as a bacteria, protozoans, or viruses) in or on the body of a suitable host b : a disease resulting from infection in different parts of the body.
• There is no cure for a virus, but vaccination can prevent them from spreading.

Are Viruses Alive? First seen as poisons, then as life-forms, then biological chemicals, viruses today are thought of as being in a gray area between living and nonliving: they cannot replicate on their own but can do so in truly living cells and can also affect the behavior of their hosts profoundly. The categorization of viruses as nonliving during much of the modern era of biological science has had an unintended consequence: it has led most researchers to ignore viruses in the study of evolution. Finally, however, scientists are beginning to appreciate viruses as fundamental players in the history of life.