Tuberculosis screening and prevention for foreign-born students: eight years experience at Ohio University

In the mid-1980s, international students enrolled at Ohio University were identified as a high-risk group for tuberculosis (TB), contributing an estimated 30%-50% of all active TB cases in the sparsely populated county where the university is located. While the student health center routinely screened all newly enrolled international students with PPD Mantoux tests, no provision for Isoniazid (INH) chemoprophylaxis was available until the Preventive Medicine/Public Health Section of Ohio University College of Osteopathic Medicine initiated a program in September 1985. In 1993, cases of active TB among international students had declined significantly from a pre-1986 rate of 97.5/100,000 student-years to 19.4/100,000 after 1986 (P < .01), while case rates among other groups in the county increased. Positive PPD reaction rates have remained high (53.6%), but less than 15% of international students who should have taken INH chemoprophylaxis by Centers for Disease Control (CDC) criteria did so. This finding suggests that other factors may have contributed to the observed decline in active cases. We examined the influence of five variables (age, gender, geographic origin, BCG vaccination status, and year of enrollment) on PPD status. In this international student population, geographic origin and BCG vaccination status were the most important contributors to positive PPD testing. We suggest that PPD status alone may no longer be sufficient to distinguish those at higher risk of developing active TB in similar populations. A changing mix in international students' geographic origin and BCG vaccination status may help explain the decrease in active case rates in the face of continued high positive PPD rates.