Latent tuberculosis infection: risks to health care students at a hospital in Lima, Peru.

SETTING

University hospital and university campus in Lima, Peru.

OBJECTIVE

To demonstrate the risk of latent tuberculosis infection (LTBI) in the hospital relative to the community.

DESIGN

Prospective cohort study of university students measuring prevalence, boosting, and conversion of tuberculin skin tests (TSTs) among health care students (HCS) and non-health care students (NHCS).

RESULTS

Among the HCS relative to NHCS, prevalence of initial positive TST was 20.9% vs. 12.2% (P < 0.001), and conversion rate was 1.1% vs. 0% (P = 0.423) at the 10 mm cut-off and 11.8% vs. 0% at the 6 mm cut-off (P = 0.00005). Multivariate analysis showed that the HCS group had a higher risk of baseline positive TST compared with the NHCS group after controlling for confounding factors (OR 1.7, 95% CI 1.1-2.6).

CONCLUSION

HCS are at greater risk than NHCS for having positive baseline TSTs and for TST conversion at the 6 mm cut-off. We conclude that the hospital we studied in Lima, Peru, poses a greater risk than the surrounding community for tuberculosis infection, and greater attention to hospital infection control measures is warranted. A higher rate of skin test boosting among the HCS cohort suggests the possibility of transient, non-progressive LTBI, which merits further study.