ABSTRACT
Epidemiology is the study of patterns of disease occurrence and the factors that influence such patterns. Historically, epidemiology was concerned with epidemics of those infectious diseases that were responsible for much suffering during the eighteenth and nineteenth centuries, such as cholera and typhoid. Nowadays, the scope of epidemiology has been extended to include acute conditions, such as the occurrence of episodes of food poisoning, and chronic diseases, such as various types of cancer.
