Tuberculosis is a chronic, recurrent, infection caused by Mycobacterium Tuberculosis, M. Bovis or M. Africanum. The common TB popular in the Philippines and other Asian countries is pulmonary tuberculosis due to M. tuberculosis. In the United States, where tuberculosis was practically under control, there has been a resurgence, attributed to immigrant carriers. In 1996, there were 21,337 cases reported. Many of these cases were also found to be resistant to the conventional drug therapy against PTB. The prevalence of PTB among Afro-Americans appears to be twice of that among whites. Tuberculosis of the lungs is transmitted by inhalation of the M. tuberculosis organism dispersed as droplet nuclei from a person with pulmonary TB whose sputum is positive. The bacteria may float in the air for several hours. Other modes of transmission are by direct hand or mouth (kissing) contact with infected saliva. Some people with pulmonary TB may not have any symptom whatsoever. The first sign could be a bloody sputum, or a chest X-ray finding of TB, a conversion to "positive" of a previously "negative" Tuberculin Skin Test, or recurrent cough and/or loss of weight. The symptoms could even be so subtle to escape attention. It is therefore important to have a high index of suspicion when a cough or weight loss persists, especially after exposure to someone with PTB. Tuberculosis is a global pandemic, with 9 million new cases of tuberculosis disease and approximately 2 million deaths each year. Ninety-eight percent of patients treated for tuberculosis in the United States between 1993 and 2007 had drug-susceptible strains.
Given current evidence and consensus, the Stop TB Partnership Laboratory Strengthening Subgroup, partner organizations, laboratory experts and the Strategic and Technical Advisory Group for tuberculosis recently endorsed the following WHO policies:
1. The revision of the definition of a new sputum smear positive pulmonary TB case, based
on the presence of at least one acid fast bacillus (AFB) in at least one sputum sample in
countries with a well functioning external quality assurance system.
2. The reduction of the number of specimens to be examined for screening of TB cases
from three to two in places where workload is very high and human resources are
limited. (If both smears are negative, then the algorithm for sputum negative cases
3. The use of liquid culture and rapid species identification to address the needs for culture
and drug susceptibility testing (DST), based on a country specific comprehensive plan for
laboratory capacity strengthening. The use of liquid cultures and rapid species
identification to be implemented as a step-wise approach.