Usually most people have heard of influenza, or in other words influenza. Influenza is a contagious respiratory disease caused by the flu that affects the nose, throat and even lungs. There are three different types of influenza viruses which are: influenza A, influenza B and influenza C. Influenza A is the most common in humans. In most cases with the flu you would only get a mild to severe illness, but sometimes it could lead to death. There's really no way to prevent the flu, but to reduce your chances you could always get the flu shot. There are many different symptoms that accompany the flu such as: fever, cough, sore throat, runny nose, body or body aches, headache, tiredness and sometimes even vomiting. It's also important to know that not everyone will have a fever from the flu. Most experts believe the virus spreads among people who have the flu when they cough, sneeze or talk. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an Original Essay Sometimes, you may get the flu simply by touching a surface that has the flu virus on it. If you have the flu and don't know you have it, you can still give it to someone. People with the flu are most contagious in the first three to four days after the onset of the illness. Some people may be contagious as early as one day before symptoms appear and five to seven days after symptoms appear. Some people with not as strong immune systems, such as children, may be able to infect people for longer than seven days. The average time to get the flu is one to four days, but the average is about two. There is no way to cure the flu, but there are things that can help prevent it. The things most people will get the seasonal flu vaccine. The seasonal flu vaccine usually contains two strains of the influenza A virus and one or two strains of the influenza B virus. The strains contained in the vaccine are the same for all types of influenza in a given year, but may change from year to year in year. Influenza is a virus that has hundreds of different strains. These strands are separated into groups known as influenza A, B, and C. Influenza A is the most common for humans. The influenza A virus is divided into further groups known as subtypes H and N. So if you see something like "H#N#", that's influenza A. There are many different types of subtypes, but there are only three different combinations. There are sixteen H subtypes and nine N subtypes. Other combinations have been found, but they are only found in animals such as pigs and birds. The three combinations most commonly found in humans are H1N1, H2N2, and H3N2. Even in these types, the influenza virus can mutate and change every year. For this reason, there are four different ways to name the influenza virus. The four ways are: host of origin, geographic location of origin, strain numbers, and year of discovery. When the CDC (United States Centers for Disease Control and Prevention) and the WHO (World Health Organization) name a new strain of influenza virus they must follow some steps. They first start with the influenza group it falls into, then as A, B, or C. They then name the host, place of origin, strain number, year of discovery, and the HN subtypes in parentheses. Please note: This is just an example. Get a custom paper from our expert writers now. Get a Custom Essay An example of an influenza A virus would look like this:.