Flu season is mostly a colloquial term used to describe the regular outbreak in flu cases, or even cases of the common cold during the late fall or winter. Viral activity such as the flu can sometimes be predicted and even tracked geographically. Flu season is most apparent in schools because the closer interactions and lower hygiene cause easier transmission. Some workplaces offer paid sick days, partly to prevent sick individuals from entering the workplace biome. Most often these minor epidemics take 3 weeks to peak, and another 3 weeks to significantly diminish.^[1] Individual cases of the cold or flu however, usually only last a few days. In some countries such as Japan and China, infected persons sometimes wear a surgical mask out of respect for others. Negatively stained flu virions. ... The flu vaccine is a vaccine to protect against the highly variable Influenza virus. ... Influenzavirus A is a genus of a family of viruses called Orthomyxoviridae in virus classification. ... The transmission and infection of H5N1 is a concern due to the global spread of H5N1 that constitutes a pandemic threat. ... Genera Influenzavirus A Influenzavirus B Influenzavirus C Isavirus Thogotovirus The Orthomyxoviridae are a family of RNA viruses which infect vertebrates. ... Negatively stained flu virions. ... The acute nasopharyngitis, often known as the common cold is a mild viral infectious disease of the nose and throat; the upper respiratory system. ... The microorganisms (bacteria and viruses) that cause disease may be transmitted from one person to another by one or more of the following means: droplet contact - coughing or sneezing on another person direct physical contact - touching an infected person indirect contact - usually by touching a contaminated surface airborne transmission - if... In ecology, a biome is a major regional group of distinctive plant and animal communities best adapted to the regions physical natural environment, latitude, altitude and terrain factors. ... A surgical mask is designed to be worn by health professionals during surgery and at other times to catch the bacteria shed from the wearers mouth and nose. ...

More recently, flu vaccinations have made efforts to stop flu season pre-emptively. Since the Northern and Southern Hemisphere have winter at different times of the year, there are actually two flu seasons each year. Therefore, the World Health Organization (assisted by the National Influenza Centers) makes two vaccine formulations every year; one for the Northern, and one for the Southern Hemisphere. The flu vaccine is a vaccine to protect against the highly variable Influenza virus. ... Insert non-formatted text here The Northern Hemisphere is the half of a planets surface (or celestial sphere) that is north of the equator (the word hemisphere literally means half ball). On the Earth, the Northern Hemisphere contains most of the land and population. ... Southern Hemisphere The Southern Hemisphere is the half of a planets surface (or celestial sphere) that is south of the equator (the word hemisphere literally means half ball). On Earth it contains four continents (part of Africa, Oceania, most of South America, and Antarctica) and four oceans (South Atlantic... WHO emblem The World Health Organization (WHO) is a specialized agency of the United Nations, acting as a coordinating authority on international public health, headquartered in Geneva, Switzerland. ... National Influenza Centers (also called National Influenza Centres) are institutions which are formally recognized as such by WHO. Among the more than 110 National Influenza Centers are the WHO collaborating centres and reference laboratories that are involved in annual influenza vaccine composition recommendations. ... A vaccine is an antigenic preparation used to produce active immunity to a disease, in order to prevent or ameliorate the effects of infection by any natural or wild strain of the organism. ...

While most influenza outbreaks in the Northern Hemisphere tend to peak in January or February, not all do. For example, the influenza pandemic of 1918 and 1919 reached peak virulence during late spring and summer worldwide, and not until October in the US. It remains unclear why outbreaks of the flu occur seasonally rather than uniformly throughout the year. The Spanish Flu Pandemic, also known as La Grippe Espagnole, or La Pesadilla, was an unusually severe and deadly strain of avian influenza, a viral infectious disease, that killed some 50 million to 100 million people worldwide over about a year in 1918 and 1919 [1]. It is thought to...

One possible explanation is that, because people are indoors more often during the winter, they are in close contact more often, and this promotes transmission from person to person. Another is that cold temperatures lead to drier air, which may dehydrate mucus, preventing the body from effectively expelling virus particles. The virus may also linger longer on exposed surfaces (doorknobs, countertops, etc.) in colder temperatures. Increased travel and visitation due to the holiday season may also play a role. ^[2]

The garden variety flu that comes around every year is caused by flu virus species Influenzavirus A, Influenzavirus B, or Influenzavirus C. The species A varieties that yearly attack humans are called "human flu virus" which is to say it is a variety of the species "avian flu virus" (species A) that has made genetic changes to adapt to its human hosts. It passes from human to human all year round and never goes away completely. When it is cold (winter in the north, summer in the south part of the world) infection from "human flu" increases something like ten fold or more. Different strains of avian flu virus circulate in different years as it is constantly mutating. The flu vaccine for the 2005 - 2006 flu season contains proteins from the coat of two subtypes of species A and from species B. Species B and C don't have subtypes. Respiratory disease properly named influenza(say: in-floo-en-zah ). Some specific varities of influenza with a vaccination available are: A-New Caledonia, A-California, B-Shanghai. ... The human immunodeficiency virus (HIV) A virus is a submicroscopic parasite that infects cells in biological organisms. ... Influenzavirus A is a genus of a family of viruses called Orthomyxoviridae in virus classification. ... Influenzavirus B is a genus in the virus family Orthomyxoviridae. ... Influenzavirus C is a genus in the virus family Orthomyxoviridae. ... In biology, a species is the basic unit of biodiversity. ... This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ... Binomial name Homo sapiens Linnaeus, 1758 Subspecies Homo sapiens idaltu  (extinct) Homo sapiens sapiens Homo (genus). ... Winter is one of the four seasons of temperate zones. ... Compass rose with north highlighted and at top North is one of the four cardinal directions, specifically the direction that, in Western culture, is treated as the primary direction: north is used (explicitly or implicitly) to define all other directions; the (visual) top edges of maps usually correspond to the... Summer is a season, defined by convention in meteorology as the whole months of June, July, and August, in the Northern hemisphere, and the whole months of December, January, and February, in the Southern hemisphere. ... A compass rose with South highlighted South is most commonly a noun, adjective, or adverb indicating direction or geography. ... The World in plate carrée projection The World In English, world is rooted in a compound of the obsolete words were, man, and eld, age; thus, its oldest meaning is age or life of man. Its primary modern meaning is the planet Earth, especially when capitalized: the World. ... An infection is the detrimental colonization of a host organism by a foreign species. ... The flu vaccine is a vaccine to protect against the highly variable Influenza virus. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... 2006 (MMVI in Roman) is a common year starting on Sunday of the Gregorian calendar. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ...

References

• ^ http://www.niaid.nih.gov/factsheets/flu.htm
• ^ http://www.npr.org/templates/story/story.php?storyId=1551913