Abstract
“The time to close the book on infectious disease” is far from near. Infections seem to be here to stay and have increased in importance in spite of enormous success in the field of prophylactic efforts, hygiene, vaccinology, and treatment. A large number of new agents and infections have appeared during the last decades. Conditions earlier thought to have other etiologies are today known to be distinct and have been proven to be of infectious origin. Infections alone can constitute major incidents, or they can be part of or a consequence of an incident. Even in the relatively new incident category of terrorism, infections must be seriously considered. Climate change and other changes in nature today constitute major threats of increasing infectious incidents. The increasing problem with antimicrobial resistance is, at present, considered to be one of the strongest disease threats. Infectious incidents are unique in the sense that they usually have an insidious onset, have a time span before they are detected as present or even as serious. Once the infection has started to spread, the development and increase can be extremely quick, even logarithmic. The extent of infectious incidents can be larger than that of most other disasters, and is best exemplified through different pandemics. The most important weapon to control infectious outbreaks or epidemics is active surveillance, leading to different kind of actions.