A prevalence survey for smear-positive tuberculosis in Thai prisons

Twenty-seven prisons in Thailand.

To measure the prevalence of smear-positive tuberculosis (TB) and to compare its detection using the World Health Organization (WHO) guidelines for prisons or the International Standards for Tuberculosis Care (ISTC) criteria.

Prisoners who were not on TB medications and who had not been treated for TB in the previous 6 months were enrolled in the survey. Prison nurses conducted a one-time mass screening using the WHO questionnaire, with follow-up sputum collection in TB suspects.

Of 71594 prisoners, 22132 (30.9%) were identified as TB suspects, and 254 were confirmed by sputum smear, for a prevalence of 354.8/100000. Males were most likely to be diagnosed with TB disease (OR 2.6), as were those transferring in from another prison versus new prisoners (OR 3.0). The positive predictive value of the WHO criteria was 1.2%, and that of the ISTC standard was 5.9%.

TB prevalence in this survey remained high. WHO guidelines, recognised as a standard, require health workers to question prisoners and measure height and weight. The ISTC standard, a single question about cough >or=2 weeks, is simple, may be asked by non-health personnel and may be a better alternative.