Many of us mistakenly believe that the swine flu is a recent mutation of the influenza virus; however, the reality is that swine flu has been with us for nearly as long as influenza itself. There are two main strains of the flu, avian and swine each of them so named for the animal they’re primarily found in when they aren’t affecting human beings. Swine flu in particular has only rarely come to affect humans and usually only results in a mild form of the flu. Generally those who become infected are those who come into very close contact with the animals such as farmers and workers at plants where the animals are butchered.
Flu Among Pigs
Swine flu made its first documented appearance in 1918 when an avian form of the flu was killing many across the globe (estimates are as high as 50 million, with a third of the world’s population infected) and was first seen as a respiratory infection of pigs. In 1930 this virus was clearly defined as affecting pigs. Having affected their populations since the 1918 influenza outbreak, both pigs and humans are affected by type A and type C influenza and have been since about this time. It’s thought by some that the 1918 outbreak first exposed pigs to the flu through contact with humans who had the virus. The cause of the 1918 outbreak is still unclear.
In 1976 a new form of swine flu broke out at Fort Dix killing the first soldier who was infected and making four others ill. The virus was in existence for only two weeks and never left the base. It did cause the focus on influenza to increase however and it was found that another form of the virus was also traveling at the time which carried on until March of that year. The discovery caused concern among health officials of the time and spurred a flu immunization for the strain in October of the same year. Unfortunately 3 senior citizens died after being immunized and a panic began about receiving the vaccine despite the fact these deaths were caused by other health problems. Only 22% of the population was immunized as a result.
1988 Walworth County Fair
In 1988 the virus killed a woman and infected others. The woman contracted the virus after visiting a hog barn at a fair and was 8 months pregnant at the time. The child was born before she passed away. Out of the 25 pigs present at that fair, 19 were found to be carrying antibodies to the swine flu but none actually carried the infection itself. Between 1 and 3 of the health care workers who cared for the woman when she was ill also contracted the virus but suffered only mild effects and the illness didn’t spread beyond them.
1998 and 2007 Swine Flu Epidemic
In 1998 the swine flu returned as an epidemic among pigs across the US. This time it was found that the virus was a recombinant of flu that had come from both humans and birds. 6 of the 8 gene segments associated with the 2009 strain originated with this form of the flu. Later in 2007, another outbreak occurred among swine in the Philippines causing a red alert in the country. The mortality rate in this case was less than 10% unless hog cholera affected those who contracted it.
All of this leads to the original outbreak in Spring of 2009. Rather than being a new form of the swine flu, H1N1 is actually a combination of swine flu and other influenza genes from both the human and avian varieties. Now, it is affecting human beings as well.