TABLE 1.

Demographic and clinical characteristics of the study populations

CharacteristicActive infectionRecent latent infectionNonrecent latent infection
Total no. of subjects167a14938
Age (yr)
    Median301351
    Interquartile range25-4111-1431-63
% (no.) of males59.3 (99)52.3 (78)71.1 (27)
Ethnic origin [% (no.)]
    Indian subcontinent61.1 (102)0.0 (0)47.4 (18)
    Black22.8 (38)0.0 (0)31.6 (12)
    Caucasian8.4 (14)0.0 (0)18.4 (7)
    Turkish0.0 (0)100 (149)0.0 (0)
    Other7.8 (13)0.0 (0)2.6 (1)
BCG vaccination status [% (no.)]
    Vaccinated58.1 (97)79.9 (119)39.5 (15)
    Unknown11.4 (19)20.0 (30)31.6 (12)
TST [% (no.)]b
    Positive63.5 (106)76.5 (114)31.6 (12)
    Unknown20.3 (34)0 (0)10.5 (4)
Comorbidity [% (no.)]
    None82.0 (137)96.6 (144)57.8 (22)
    Previous TB9.0 (15)0 (0)0 (0)
    Diabetes5.4 (9)0 (0)21.1 (8)
    Human immunodeficiency virus infection4.2 (7)0 (0)0 (0)
    Sarcoid1.8 (3)0 (0)0 (0)
    Alcohol dependence1.2 (2)0 (0)2.6 (1)
    Chronic renal failure0.6 (1)0 (0)2.6 (1)
    Carcinoma0 (0)0 (0)2.6 (1)
    Other9.0 (15)c3.4 (5)28.9 (11)d
  • a The infections of 134 of the subjects were confirmed by culture, and 33 subjects had highly probable active infections (they had clinical and radiological features highly suggestive of TB unlikely to be caused by other disease, and a decision to treat was made by a clinician; there was an appropriate response to therapy and supportive histology where available). Histological findings were available for 15 of the latter 33 cases, and they were supportive in all 15 cases; the subjects had granulomas (n = 13), epithelioid cells (n = 6), caseation (n = 5), and necrosis with acute inflammation (n = 1).

  • b Induration of ≥15 mm in the Mantoux test or grade 3 or 4 in the Heaf test was considered a positive result.

  • c Two subjects had asthma, two subjects had epilepsy, two subjects had ischemic heart disease, two subjects had viral hepatitis, one subject had carpal tunnel syndrome, one subject had chronic obstructive pulmonary disease, one subject had idiopathic thrombocytopaenic purpura, one subject had iron deficiency anemia, one subject had pernicious anemia, and one subject had schizophrenia.

  • d Four subjects had ischemic heart disease, three subjects had asthma, one subject used drugs intravenously, one subject had multiple sclerosis, one subject had osteoarthritis, and one subject had Wegener's granulomatosis. Only one patient, who was suffering from Wegener's granulomatosis, was receiving therapeutic immunosuppression therapy consisting of 1 g twice daily of mycophenolate mofetil and 10 to 15 mg of oral prednisolone.