Tuberculin skin test conversion rate among short-term health care workers returning from Gaborone, Botswana

Our objective was to determine tuberculin skin test conversion rate of health care workers traveling to Botswana. The rate of tuberculin skin test conversion was 4.2% for the entire group studied or 6.87 per 1000 person weeks (95% CI, 1.87-17.60).

International travel by health care workers traveling from low incidence countries to areas of the world where tuberculosis is highly endemic places the health care worker at an increased risk of acquiring tuberculosis.

To determine the tuberculin skin test conversion rate of health care workers living in the United States with previously negative tuberculin skin test results working for less than 1 year in a hospital in Botswana where tuberculosis is highly endemic.

We performed a cross-sectional survey among health care workers affiliated with the University of Pennsylvania School of Medicine who participated in patient care in Botswana between July 1st 2004 and June 30th 2009. We recruited health care workers after returning from Botswana who had a documented negative tuberculin skin test in the year prior to travel, who spent at least 2 weeks but not more than 1 year and who had a documented tuberculin skin test 2-3 months post travel. The main study outcome was a positive tuberculin skin test 6-12 weeks after returning from Botswana, defined by an area of at least 10mm induration 48-72h after placement of the tuberculin skin test.

95 Subjects participated in the study and there were 4 tuberculin skin test conversions. The rate of tuberculin skin test conversion in our study population was 4.2% for the entire group studied or 6.87 per 1000 person weeks (95% CI, 1.87-17.60).

The tuberculin skin test conversion rate was higher than the reported conversion rates for those not working in a health care setting.