Investigation of the Spanish flu epidemic of 1918 and its impact on Iranian society during the Qajar period with a Focus on documentary research

During World War I, Iran was hit by the deadly Spanish flu, which is considered the worst disease of the 20th century. Three to four waves of Spanish Flu from the spring of 1918 to the summer of 1919/ Rabi al-Thani 1336 to Rajab 1337 AH hit Iran and most countries in the world. The disease came from outside Iran's borders, and foreign factors such as the presence of British, Russian, and Ottoman forces played an important role in accelerating its spread. Domestically, political and economic disintegration and worn and inefficient health infrastructure contributed to the disaster. As a result of this disease, between 10 and 20 percent of Iran's population lost their lives, and its psychological and social effects will cast a shadow over Iranian society for years to come. The question of the article is: How did the Spanish flu spread in Iran and what impact did it have on Iranian society during the Qajar period?The present research was conducted using a library method. Historical sources, memoirs, travelogues of Europeans and archival documents of the Ministry of Foreign Affairs were used in the research. The results of this research show that the deplorable conditions in Iran during World War I and the high mortality rate were not only due to famine, drought, and the occurrence of historical diseases, but that the three deadly waves of the Spanish flu brought the living conditions of Iranians to a very acute stage.