evolution, but dont tell the theists i told you that lol.

Evolution

Those of you who followed the tournament of pandemics know that influenza came very close to winning the whole thing. It came in second to tuberculosis, because influenza was a couple of mutations away from true pandemic capacity. The current swine flu situation? Well, let's just say that if we ran the tournament again, I wouldn't necessarily bet on TB. The story, in a nutshell: a form of influenza generally found in pigs mutated to infect people. This is much the same as happened with avian influenza. Avian influenza, however, does not spread from person-to-person. Swine flu does. So it's a new form to which people have no immunity, and it's going person to person. It is also showing a high mortality rates in Mexico. (ominous side note: the current strain of swine flu infecting humans is an H1N1 virus type, as was the Spanish flu which went pandemic in 1918) It seems clear to me that this new form of flu is spreading rapidly; it will achieve pandemic status quickly. That is not the question. The questions is whether it will be a deadly pandemic. We don't know yet what mortality rates will look like. Swine flu responds to oseltamivir/Tamiflu (at the moment) and zanamivir/Relenza. In the US, it's been a reasonably mild and treatable form of the flu. In Mexico it's been much worse. Just how bad things get depends on how this influenza looks everywhere else. Evolution of the Flu Virus. Human flu virus has two proteins on its surface that can be recognized and attacked by the body's defenses (immune system). They are called hemagglutinins (H) and neuraminidase (N). A person's defense learns to recognize the surface proteins either by being infected with flu virus and recovering or by being vaccinated with a vaccine that contains the H and N proteins (flu shot). After that, any virus that infects with the same H and N on its surface will be quickly recognized and stopped, causing either a mild illness or no illness. This type of defense is known as immunity. The flu can evade a person's defenses by changing the H or N on its surface to one that has not been learned by that person. Type A flu has 16 different H subtypes and nine N subtypes. Minor changes in subtypes of H and N to a form not well recognized by the defenses of people who were previously exposed or vaccinated are responsible for the yearly epidemics of flu during the winter months. Often people have partial immunity (defenses) since strains are similar to those that have circulated in prior years, and vaccines developed from strains most common in the previous year are often effective. However, every 50 to 100 years, the flu virus manages to completely change the H and N on its surface to ones that most humans currently living have not been exposed to; thus, we have no immunity or defense against these altered forms of the virus. When this happens, there is a risk of a worldwide pandemic with a very large percentage of people becoming infected and ill from the flu. One way the flu virus could make such a change would be to combine with parts of the bird flu virus to form a new strain that is both adapted to spread easily between humans and has bird type H and N proteins that human defenses have not learned, and thus humans would have no immunity. Bird flu viruses are related to human influenza viruses but include subtypes that occur mainly in birds. The subtype causing bird flu or avian influenza A among poultry in Asia and elsewhere is known as H5N1 virus. This same subtype is causing limited human infections and deaths. If any of these changes were to occur that allowed a deadly virus to also be transmitted easily from person to person, then a pandemic could begin. The last recorded flu pandemic was 1918-1920, during which over 20 million people worldwide died from flu or its complications. Scientists now believe that an H5N1 subtype, also bird flu, was responsible for this pandemic. Like the current strains of bird flu, the 1918 virus caused a very high death rate even in otherwise healthy people; however, unlike the current strain, it had also developed the ability to spread easily between people.

like anything else in life, if your surroundings become unlivable, life must find a way to adapt to a new situation. for example, cockroaches. a bug spray is made that kills them. some are not killed, and provide their offspring with the ability to not be affected by that particular spray (immune to it). so then a new and stronger spray has to be made.