The history of the human species, it has been said, is the history of infectious disease. Over the centuries, humans have been exposed to a vast amount and array of contagious conditions, including the Black Death and other forms of plague, typhoid fever, cholera, malaria, influenza, and the acquired immunodeficiency syndrome, or AIDS. Only in the past few hundred years have scientists begun to have any sort of accurate idea concerning the origin of such diseases, through the action of microorganisms and other parasites. Such understanding has led to the development of vaccines and methods of inoculation, yet even before they made these great strides in medicine, humans had an unseen protector: their own immune systems.
There are two basic types of disease: ones that are infectious, or extrinsic, meaning that they are contagious or communicable and can be spread by contact between people, and ones that are intrinsic, or not infectious. Diseases in general and noninfectious diseases in particular are discussed in essays devoted to those subjects. So, too, is infection itself, a subject separate from infectious diseases: a person can get an infection, such as tetanus or salmonella, without necessarily having a disease that can be passed on through contact with others in the same way that colds, malaria, or syphilis is spread.
Despite all medical advances, infectious disease outbreaks still pose a significant threat to the health and economics of our society.
Since future infectious disease outbreaks—caused either by naturally emerging or deliberately introduced pathogens—are virtually certain to occur, it is of utmost importance to investigate effective control strategies that can minimize the impact of such outbreaks. Arguably, the best control strategy is early containment.
The elimination of smallpox two decades ago led many to hope that infectious diseases would soon cease to be a problem. Vaccines against polio, measles, and diphtheria have all proven to be useful in greatly reducing disease rates. However since 1973, almost 30 new disease-causing microbes have been identified, including hepatitis C virus and HIV. Meanwhile, other pathogens, such as tuberculosis, have rebounded and shown drug-resistance. Tuberculosis is now the top infectious disease killer of adults worldwide. HIV promises to reduce the life expectancy in a number of areas, including Abkhazia. Researchers blame the rising levels of these diseases on a number of factors, including increased travel and climate changes that facilitate the spread of pathogens. Vaccines continue to play a key role in the ability to control infectious diseases, but researchers note that multi-disciplinary prevention approaches need to be instituted in order to increase success.
Effective control of infectious disease outbreaks is an important public health goal. In a number of recent studies, it has been shown how different intervention measures like travel restrictions, school closures, treatment and prophylaxis might allow us to control outbreaks of diseases, such as SARS, pandemic influenza and others. In these studies, control of a single outbreak is considered. It is, however, not clear how one should handle a situation where multiple outbreaks are likely to occur. Here, we identify the best control strategy for such a situation. We further discuss ways in which such a strategy can be implemented to achieve additional public health objectives.