History of Influenza: Pandemics in Iran and the World

Influenza type A virus is well known for its capability of genetic changes either through antigen drift or antigen shift. Antigen shift is derived from reassortment of gene segments between viruses, and may result in an antigenically novel virus capable of causing a worldwide pandemic (1). Pandemic influenza was recorded in 1830 33, 1898 1900, four times in the 20 century (2) and once in the 21 century (3). The current paper aimed to discuss the time of influenza pandemics occurrence in Iran (2). Pandemic influenza, 1833: The first established evidence of influenza in Iran is back to the summer of 1833, when it happened with great virulence in Tehran. It is said that this pandemic arrived via trade routes from Syria and Constantinople, which was a part of a larger global pandemic and had involved thousands of people in Asia and Europe. Every day, among the capital’s citizenry, dozens of people died, and the corpses were found in the corner of streets (4). Dr. Cyril Elgood wrote in his book about this event as follows: “During the summer of 1833, a strange epidemic, possibly influenza, broke out in Tehran. It even pierced the boasted immunity of the staff of the mission. Even FathAli Shah was attacked. His doctors reported that he had a severe fever and ague. The state of the city was even worse than that of the villages of Shimran. The deaths ran into many dozens a day (5)”. Pandemic influenza, 1918 (Spanish flu): Illness from the 1918 flu pandemic, also known as the Spanish flu, came on quickly. It was due to A (H1N1) influenza virus. Some people felt fine in the morning but died by nightfall. People who caught the Spanish flu but did not die from it often died from complications caused by the bacteria such as pneumonia. During the 1918 pandemic, approximately 20% 40% of the worldwide population became ill, an estimated 50 million people died, unlike earlier pandemics and seasonal flu outbreaks, the 1918 pandemic flu had high mortality rates among healthy adults. In fact, the illness and mortality rates were highest among adults 20 50 years old (6).