Science and the challenge of emerging and re-emerging diseases

The twentieth century has seen great strides in the fight against infectious diseases, Yet, despite advances in the development of antibiotics and vaccines, the fight against infectious diseases is far from over. Indeed, recent decades have seen an upsurge in the emergence or resurgence of infectious diseases, stemming from the increasing world population, rapid international travel on a large scale, and increased exposure of human beings to disease vectors in nature, A shift of resources away from infectious disease control, public health and sanitation has been aggravated by the fact that antibiotics which were once effective against some of the most common human infections have gradually become ineffective, In addition, changes to the environment may bring the animals that carry disease into closer contact with human beings, During the last quarter-century, more than thirty disease-carrying micro-organisms have emerged in human populations, some of which cause dramatic and lethal disease in localized outbreaks or over great distances, at the cost of enormous suffering and expense to society, Meanwhile, several common diseases have re-emerged and spread or have increased rapidly in prevalence after periods when they were no longer considered to be a problem.