Positive Tuberculin Skin Test Among Health Care Workers: Prevalence and Risk Factors in Teaching Hospitals of a Highly Endemic Region for Tuberculosis, Zahedan, Iran

Tuberculosis (TB) is not only considered as a community acquired disease, but also as an occupational infection. Health care workers (HCWs) in several countries show an increasing pattern for TB. The current study aimed to determine the prevalence of positive tuberculin skin test (TST) among HCWs in a highly endemic area for TB in Iran, namely Zahedan, the capital of Sistan and Baluchestan province, located in Southeast of Iran, near the border of Afghanistan. In a cross sectional study in 2009, 328 HCWs from all five teaching hospitals in Zahedan were recruited. Inclusion criteria were lack of history of TB in family, receiving BCG vaccination within the first six month after the birth without later booster dose. Age, gender, job, working experience, history of exposure to a known patient with TB and TB vaccine scar were registered. The outcome was positive results during two TSTs (induration > 10 mm). A logistic regression was implemented to determine the predictors of positive TST result. TST was positive in 198 (60.4%) health care workers out of 328. Likelihood of positive TST among HCWs increased in nurses (OR = 4.617, 95% CI = 1.181-18.054, P = 0.028), increasing working experience (OR = 1.178, 95% CI = 1.131 - 1.226, P < 0.001), and history of exposure to patients with TB (OR = 9.035, 95% CI = 4.018 - 20.315, P < 0.001). Age, gender and BCG vaccination scar were not associated with TST results (P > 0.05). The prevalence of positive TST in HCWs in teaching hospitals in Zahedan is so high. Tuberculosis prevention programs should be implemented for HCWs and personnel of hospitals in Zahedan.