Tuberculosis: an ancient and evergreen disease

Abstract

Tuberculosis (TB) is a fascinating disease, and still represents a “special laboratory” for immunologists, pathologists, radiologists, respiratory physicians, paediatricians, public-health experts and other specialists. TB, after affecting mammoths and Egyptian mummies, has infected a large fraction of mankind (about one third of them, according to Mantoux-based estimates) of whom no more than 10% of the immunocompetent and up to 50% of immunocompromised individuals, at the end, develop the disease [1, 2]. Due to the consistent transmission rules of TB and its role in medical history, TB epidemiologists have been forced to develop sophisticated epidemiological models aimed at better understanding TB and how better the disease can be controlled and, eventually, eliminated [3, 4]. According to the natural history model, one case of infectious TB is likely to infect approximately 10 persons per year for 2 yrs, thus generating 20 infected individuals [1]. Given that the lifetime breakdown rate ( e.g . the proportion of individuals who will develop TB disease) is estimated to be 10%, and that ∼50% of cases are likely to become sputum smear-positive, one infectious source is likely to add at least another infectious (sputum smear-positive) case to the existing community burden [1, 2]. The World Health Organization (WHO)-recommended interventions, from which the DOTS strategy expanded into the larger vision of the Stop TB Strategy [5], have been effective in decreasing the epidemic curve by recommending, in essence, a set of interventions which need to implemented in order to reach the World Health Assembly targets, e.g. to ensure rapid diagnosis of 70% of existing sputum smear-positive cases and effective treatment of 85% …