Global progress in infectious disease control.

There is both good news and bad news concerning infectious disease control globally. The good news is that smallpox has been eradicated, eradication of poliomyelitis and guinea worm disease is on track, and many infectious diseases are under effective control in much of the world. The advances are primarily the result of improved sanitation, effective use of vaccines, and introduction and use of specific therapies (whose impact has primarily been on mortality, rather than incidence). The bad news is that infectious diseases are still the leading cause of death world-wide, new diseases are emerging, old diseases are re-emerging, there are ominous interactions between diseases, and antibiotic resistance is emerging as a major problem. There are many promising developments for the future, including new and improved vaccines, new specific therapies, and new strategies to deal with infectious disease. However, unless eradicated, infectious diseases remain a threat and require continuous efforts to be kept under control. Given the ability of infectious agents to evolve, it is certain that the future will also hold new problems and new diseases.