Revisiting emerging infectious diseases: the unfinished agenda.

Infectious diseases present a formidable threat to the world today. Not only are new infectious diseases emerging, but those presumed to be contained or eradicated are re-emerging. Developing nations, with the least resources to respond, bear the greatest burden of this threat. However, with the potential to spread rapidly and ubiquitously, infectious diseases present a significant risk to the health and development of all nations. No country or population is immune, and geographic and political barriers offer little protection. Many factors facilitate the spread of infectious diseases, including globalization of travel and trade, weakening of national and international public health infrastructure, deterioration of socioeconomic conditions, and heightened political and civil strife in some developing nations. These conditions render populations more vulnerable to infections and provide an environment conducive to the transmission of infectious diseases. Compounding these risk factors is the emergence of another threat: antimicrobial resistance. Antimicrobial drugs are rapidly losing their effectiveness because of their misuse. As a result, the global health community is confronted with the daunting task of combating more offenders with fewer defenses.