Encephalitis in Elderly Population

The elderly population is increasing worldwide. Population of people above 65 years old was 420 million in the year 2000, and is estimated to be 973 million in 2030 (Centers for disease control and prevention [CDCP], 2003). Mortality rate related to infectious diseases decreased after the discovery of anibiotics, particularly in the second half of the twentieth century, however it is stil being a problem in elderly age group. Several immun alterations arise with aging and these alterations make elderly people more vulnerable to infections. In addition, body composition changes with aging, chronic diseases such as hypertension, diabetes mellitus and cardiac failure are more frequent in elderly age group, so this multi-factorial situation also reduces the immunological resistance to infections. For all these reasons, encephalitis is more frequent in elderly people as compared to younger individuals and it usually causes clinically a more severe course. Encephalitis in elderly deserves a more sensitive approach. The disease may be difficultly perceived by clinicians for some reasons. Premorbid brain disorders such as dementia and stroke especially, may lead to diagnostic delay. Numerous co-morbid situations in this age group may lessen the efficiency of treatment and may bring about seconder problems. Therefore encephalitis in elderly may result in severe central nervous system damage, high morbidity and mortality.