Tuberculosis in the elderly

Tuberculosis (TB) today remains one of the world's most lethal infectious diseases. An estimated one-third of the world's population is infected with the tubercle bacillus-Mycobacterium tuberculosis (Mtb), and 7 to 8 million people develop TB disease each year (27). For purpose of clarity, TB infection (latent TB) is defined as harboring Mtb without evidence of active infection, and TB disease is active infection without Mtb based on clinical and laboratory findings. Recognizing that TB has been one of the most neglected international health problems and that the TB epidemic is rampant in many parts of the world, the World Health Organization (WHO) declared TB to be a global health emergency in 1993 (23). Despite the steady decline in TB cases since this time resulting from the overall implementation of more effective infection control practices, directly observed therapy (DOT), and efforts to control the human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) epidemic, preventive and control strategies among other high-risk populations such as the elderly evidently remain a clinical and epidemiological challenge. The geriatric population among all ethnic groups and both genders, represent the largest reservoir of TB infection, particularly in developed nations (9). Clinical features of TB in older adults may be atypical, non-specific, and confused with concomitant age-related diseases (28). Underlying acute or chronic diseases, malnutrition, and the biological changes with aging, can disrupt integumental barriers, impair microbial clearance mechanisms, and contribute to the expected age-associated decline in cellular immune responses to infecting agents such as Mtb. Diagnosis of TB can be difficult and consequently overlooked; this treatable infection may unfortunately be recognized only at autopsy. Furthermore, therapy of TB in the elderly is challenging because of the increased incidence of adverse drug reactions. Optimal treatment of associated chronic diseases, minimization of invasive procedures, limitation of polypharmacy, and adequate nutritional support are essential for this vulnerable population. The institutionalized elderly in addition are especially at high risk for reactivation of latent TB as well as susceptible to new TB infection. This article will discuss the global epidemiology, pathogenesis and immunologic aspects, unique clinical consideration, treatment and prevention of TB, briefly inclusive of the recent published guidelines for targeted tuberculin testing and treatment of latent TB infection as it pertains to the elderly.