Evaluation and follow-up of infectious tuberculosis at the University of Ottawa

A case of active infectious pulmonary tuberculosis (tb) in a recent immigrant to Canada was identified at the University of Ottawa. The student was attending classes regularly and coughing for six months before the diagnosis of infectious pulmonary tb was made. Investigation carried out by the Ottawa-Carleton Health Department identified 871 student contacts. Of the 871 contacts, 773 (89%) were available for testing and follow-up. Initial skin testing with purified protein derivative (ppd) was positive in 149 contacts. Of the 602 contacts testing negative initially 399 (66%) returned for 12-week retesting. Eleven skin test converters were identified. All 160 contacts with positive ppd had negative chest x-ray and were given isoniazid prophylaxis for six months. The estimated cost of the process of contact tracing, testing, follow-up and treatment was $34,036. Although pre-immigration screening policies for tb do exist, additional pre- and postimmigration measures could help in the early detection of active tb and the prevention of its spread.