Swine flu is the common name used to indicate a new type of influenza virus (flu) that causes infection in man. The infection is called swine flu as the virus is believed to have probably originated in pigs. The origin of the disease is currently being investigated. In general swine influenza is a disease of the pigs. Frequent outbreaks of swine flu occur in pigs worldwide. The virus usually does not infect human beings, but it can infect people (rarely) who have close contact with pigs. A sub-type of swine influenza virus, H1N1 strain causes swine flu in mans.
The symptoms of swine flu are very much like seasonal (regular) flu that includes fever (more than 38°C) associated with aching muscles, sore throat and/or a dry cough. In most people the infection resolves within a week without any specific treatment. The exact duration of incubation period of the virus is not known. It is probably two to five days but can be up to seven days. A person with the infection is most infectious shortly after he or she develops the symptom, and remains infective for up to five days (seven days in children). The infectiousness of a person decreases as the symptoms start to subside and the person is not infective after the symptoms settle.
The human version of H1N1 sub-type of virus was initially identified in Mexico in April 2009. Since then the virus has spread worldwide (become pandemic). As it is a new type of flu virus and most people do not have resistance to it; it has spread rapidly worldwide.
Flu pandemics take place periodically. In the last century three pandemics occurred in 1918, 1957 and 1968. Millions of people died in these pandemics globally. In the current swine flu pandemic hundreds of people have died globally. However it is not yet clear how big the threat is, and there is a high probability that the viruses can mutate to become more potent (stronger). Hence scientists are advising caution.