Before the advent of chemotherapy, tuberculosis was one of the major causes of death in both Western [1] and also several non- Western countries [2]. While effective chemotherapy for tuberculosis has been available since the 1950s (isoniazid (INH) was introduced in 1952, the less effective para-aminosalicylic acid (PAS) and streptomycin slightly earlier [3]) the prognosis of untreated tuberculosis is still of great importance, as many patients will not receive appropriate treatment because their condition was never properly diagnosed as tuberculosis. For example, both the Cambodian [4] and Vietnamese [5] prevalence survey show that only about 20% of tuberculosis-patients identified in these surveys were on treatment at the time of the survey
