[Transmission of tuberculosis in the prisons of Madrid]

Prisons are recognized as high-risk settings for tuberculosis transmission. The purpose of this study was to describe the characteristics of prisoners with tuberculosis and to determine the extent of transmission of tuberculosis in the prison population of Madrid.

Patients with positive culture for Mycobacterium tuberculosis between 1997 and 1998 from the prison system of Madrid were included. The medical records for these patients were reviewed, and they were also interviewed. Patients were included in clusters when their isolates contained 1) six or more IS6110 bands in an identical pattern or 2) five or fewer IS6110 bands that matched identically and had an identical spoligotyping pattern.

Culture-proven tuberculosis was diagnosed in 97 prisoners (case rate: 693 per 100.000 per year). Isolates from 73 (75%) patients were available for fingerprinting. The mean age of these patients was 33 yr (SD: 6,9), 92% were male, and 14% were immigrants. Seventy-one percent (71%) of patients were HIV-positive, 32% were active intravenous drug users and 70% nonintravenous drug users in the last two years. Primary drug resistance to isoniazid was 1,8%. Forty-one percent of prisoners (41%) were grouped in 9 clusters. Epidemiological links were found in 37% of clustered patients. Risk factors for clustering were not detected.

The results suggest recent transmission of tuberculosis in the prisons of Madrid. It is essential that correctional facilities comply fully with the recomendations for prevention and control of tuberculosis.