There were several pandemics and notable epidemics in the 20th century. The three pandemics occurred in 1918, 1957 and 1968. These were known as the Spanish, Asian and Hong Kong influenza, they are now acknowledged to represent three different antigenic subtypes of influenza A which are H1N1, H2N2 and H3N2. There were also three epidemics which occurred in 1947, 1977 and 1976.
1918 pandemic, the Spanish Flu
The Spanish flu of 1918 was a category five and was usually severe and deadly. The Influenza A virus was subtype H1N1. It lasted from 1918 to 1919 and is claimed as the greatest medical holocaust in history killing 50 to 100 million people. It is thought this flu killed more people than those that were killed by the Black Death. It is estimated to have killed over one fifth of the world’s population. The onslaught of this virus was severe and unusual that the virus was misdiagnosed as dengue, cholera or typhoid. The majority of deaths were due to bacterial pneumonia which was a secondary infection cause by influenza but the virus also killed people directly causing massive hemorrhage and edema lungs.
The Spanish flu pandemic spread from the Pacific to the Arctic. The unusually severe disease killed between 2 and 20% of those that were infected. Another unusual factor of this pandemic was that it killed young adults and 65% of those that died were under the age of 65 and more than half were between the ages of 20 to 40 years old. This was a stray from the norm as usually pandemics affect the very young or the very old. It is estimated that 25 million may have been killed in the first 25 weeks of the onslaught of the Spanish flu.
1957 pandemic Asian
The 1957 pandemic was called the Asian influenza. During the time of the 1918 pandemic influenza had gone back to its normal pattern with less virulence through the 30’s, 40’s and 50’s, that is until 1957. This was the first time there was rapid global increase of influenza virus and the first time that researchers had the virus accessible for laboratory investigation. When an epidemic was described in Hong Kong that involved over 250,000 people they acknowledged they were faced with a virus that they knew nothing about. They obtained a sample of this virus in the United States, three weeks, later and it showed that the virus alone without any co invaders was deadly.
The Asian flu was a category 2 pandemic. It originated in China in the early part of 1956 and lasted until 1958. Its origin came from wild ducks combined with a pre existing human strain. This virus was first diagnosed in Guizhou. It spread to Singapore in February of 1957 and reached Hong Kong by April. It entered the US in June. The death toll in the United States was approximately 69,800. This flu affected the elderly who were very vulnerable. This flu killed approximately one to four million people.
The Hong Kong flu 1968 to 1969
The Hong Kong flu was rated as a category 2 flu pandemic. This flu was caused by the virus H3N2 which had descended from the H2N2 by mutating. Some of the genes from multiple subtypes reasserted to form a new virus. The Hong Kong flu pandemic is estimated to have killed one million people worldwide. It was those that ere over the age of 65 that had the greatest death rates. In the United States this flu killed approximately 33,800 people.
In 1946 an outbreak of influenza occurred in Japan and Korea in American troops. This flu spread to other military bases in the US including Fort Monmouth, New Jersey. This is where the prototype FM-1 strain was isolated. This epidemic was notable due to the initial complexity in establishing its cause as influenza A virus due to its considerable antigenic differences from the other influenzas. This epidemic has often been thought of as a mild pandemic due to the fact that although it was globally distributed it caused very few deaths.
There was a vaccine at the time that turned out to be utterly ineffective. Unlike the other influenzas of 43 to 44 and 44 to 45 the vaccine did not work this time. This proved that this virus had taken on a new life that the researchers had to deal with. For the first time there was a correlation of influenza to group A streptococcal carriage and disease.
This epidemic was aborted due to the HA mutant virus, X-53 was selected from X-53 and was produced later and used in the mass vaccination of 43,000,000 people. No cases were found outside of Fort Dix at that time and in the months that would follow the complications of Guillain-Barre syndrome occurred. This made the use of this vaccine a disaster. This virus had a way of disappearing in the summer and returning in the winter but at the time this wasn’t noted.
This influenza was first noticed in the Soviet Union in November 1977 however, later it was determined that it had started in China in May of the same year. This influenza seemed to affect people that were the age of 25 and became a rapidly spreading virus. This virus proved to be mild but still had the typical symptoms of influenza. This had researchers wondering if the previous infection of 1976 had been lying dormant and had been somehow included in the injections that were given in the previous epidemic. This epidemic lead to more questions than answers and the final answer to the 1977 epidemic is not known yet.
April 2009 epidemic
The epidemic that is passing through countries today is still another virus that have mutated into something new. The swine flu influenza that is among us now is a combination of swine, avian and human. So once again researchers are searching for the elusive cause of this flu and as of today there is still no vaccine to fight it. At the present time we are one level away from a pandemic.