Infectious diseases in the elderly.

As the percent of our population over age 65 increases, infectious disease in this group is becoming a serious public health concern. Much of our knowledge of infections in the elderly is based on clinical experience and lacks a firm scientific foundation. The increased risk of infections observed with aging may be due to physiologic changes that accompany "normal" aging or the age-associated chronic diseases and the medical, surgical, and diagnostic interventions that accompany them. Epidemiologic studies on populations of well and hospitalized older persons in defined age ranges are needed to examine the relation between specific infectious diseases and risk factors. Although the increased susceptibility of older persons to infectious diseases frequently has been attributed to the decline in immune function that occurs with aging, there are very few data confirming this hypothesis. Additional research is clearly needed on other contributory factors such as nutrition, ciliary transport, bacterial adherence, neutrophil and macrophage function, and complement.