HISTORICAL ORIGIN AND CURRENT STATE OF INFECTIOUS DISEASES DEPARTMENT OF INFECTIOUS DISEASES

Abstract

Given the ubiquitous nature of microorganisms and the many occasions on which they come into contact with humans, it is surprising how infrequently infectious diseases occur. The reason why some organisms can peacefully coexist with humans while others go on to produce disease lies in the nature of the interaction between microbe and host. Much has been learnt in recent years about mechanisms of microbial disease, especially at the molecular and cellular levels. There is a growing awareness of the active contribution of the environmental context of infection. Knowledge of these processes is necessary to understand how to diagnose, treat and prevent infection effectively. The initial encounter with a new microbial species may result in nothing more than short-lived contact with an external body surface. The microorganism needs to survive and multiply under local conditions (e.g. of temperature and pH) to establish itself in its new habitat. It must successfully compete against an established indigenous microbial flora and resist local defence mechanisms.