Should Tuberculosis Prophylaxis Be Given for the Chronically Dialyzed Patients?

Accessible online at: www.karger.com/journals/nef Until the middle of this century, tuberculosis was, in Dickens’ words, ‘a disease which medicine never cured, wealth warded off, or poverty could boast exemption from – which sometimes moves in giant strides, and sometimes at a tardy sluggish pace, but, slow or quick, is ever sure and certain’ [1]. Mycobacterium tuberculosis is an extremely successful pathogen that continues to thrive in developing countries and is re-emerging in the industrialized world. Globally, it remains a more frequent cause of death than any other infectious agent [2]. Approximately a third of the world’s population is infected with M. tuberculosis, and the World Health Organization estimated that in 1996 there were 8 million new cases of tuberculosis and 3 million deaths from the disease [2]. The sinister synergy between this disease of antiquity and the newer pathogen human immunodeficiency virus is responsible for the death of about a third of all patients with AIDS in Africa [3]. Yet progression to disease and death is far from an inevitable consequence of exposure. There is dramatic variability in the rates of infection among persons exposed to different sources of infection, and of those infected, approximately 90% never become ill. The inability to predict whose patients are most likely to transmit infection and who among those infected will have the disease and infect others remains a major barrier to optimal public health and patient care. Host resistance to M. tuberculosis is mediated by cellular immunity as this is impaired in patients with chronic renal failure [4], the incidence of tuberculosis in dialyzed patients should be high. Cellular and humoral immune responses are suppressed in uremic subjects [5]. The increase in sister chromatid exchange (SCE), chromosal aberrations, tumor markers and the impaired cell function have been reported [6–8]. Uremia thus induces a remarkable suppression of the immune status. In addition, patients receiving hemodialysis spend prolonged periods of time together in health-care facilities, thereby increasing the potential for tuberculosis transmission if a patient has active disease. For these reasons, routine tuberculosis screening of hemodialysis patients has been recommended [9]. Although the Mantoux tuberculin skin test remains the most useful screening tool, cutaneous anergy decreases the accuracy of the test. End-stage renal failure patients on chronic dialysis are prone to tuberculous infection due to a defect in cellular immunity. The incidence is reported to be 10–16 times higher than that in the general population [10–14]. One in every 3 people in the world is infected with M. tuberculosis, and observed rates of new tuberculosis infection are on the increase, especially in the third world [15–18]. In the ‘rich’ countries, latent tuberculosis can be reactivated in a number of ‘high-risk’ patient populations such as AIDS, silicosis, immunosuppression, malnutrition and end-stage renal failure [15–17]. Worldwide tuberculosis