Sarah Shohani - Ph.D. student of History, Department of History, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran
Seyed Mohammad Sheikhahmadi - Assistant Professor, Department of History, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran
Kaivan Shafei - Assistant Professor, Department of History, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran
Ruhollah Bahrami - Associate Professor, Department of History, Razi University, Kermanshah, Iran

Worldwide, infectious diseases have been one of the main factors of premature deaths for a long time. Due to the lack of proper social and cultural conditions, Iran suffered a lack of hygiene, particularly in provinces, until the end of the Qajar era. As Hamedan was located on the east-west transporting routes, it was exposed to infectious diseases mainly because of the presence of foreign and domestic merchants as well as traders and pilgrimage caravans. This study is to investigate the outbreak of infectious diseases in Hamedan during the Qajar period and their consequences on demographic transformations and the mortality rate. Regarding methodology, a historical, descriptive-analytic method has been used in the current study, and the data has been gathered using the documentary method. The documents and studies show that infectious diseases caused a population decrease in Hamedan province in the Qajar period. It is worth mentioning that the pandemics of infectious diseases, particularly Cholera and Plague, occurred in Hamedan during this period, one of the primary reasons for the population decrease in this province. Findings show that public ignorance, lack of proper hygiene, primitive, inappropriate routes, as well as poor performance of local and central rulers, primarily affected the increase of mortality and decrease of the population rate.

Hamedan, Qajar, Population decline, Communicable diseases, History of medicine, Iran