Perspective: aging and infectious diseases: past, present, and future.

As we enter into the 21st century, infectious disease specialists will be managing a greater number and proportion of patients with infections who are > or = 65 years old. Much has been learned about aging, host resistance, and infections over the past 15 years. However, if we are to meet the challenge of the complex issues of geriatric infectious diseases, infectious disease clinicians, teachers, and researchers must assume a more proactive role in clinical care, training, education, and research on problems and issues confronting the aging population.