Chemoprophylaxis trial in Canadian Eskimos

Area of Science:

• Public Health
• Infectious Diseases
• Tuberculosis Research

Background:

• Tuberculosis (TB) remains a significant global health challenge.
• Identifying individuals at high risk for developing active TB is crucial for prevention strategies.
• Preventive therapy aims to reduce the incidence of active disease in at-risk populations.

Purpose of the Study:

• To evaluate the efficacy of a supervised, intermittent preventive treatment regimen for individuals with inactive tuberculosis, positive tuberculin reactions, or large reactions after BCG vaccination.
• To assess the risk of developing active TB in treated versus control groups.

Main Methods:

• A cohort of 120 individuals with inactive TB, 165 positive tuberculin reactors, and 103 BCG-vaccinated individuals with large tuberculin reactions received supervised thrice-weekly isoniazid and ethambutol for 18 months.
• A control group of 217 individuals was observed without specific preventive treatment.
• Follow-up observation averaged 34.8 months for all participants.

Main Results:

• Over 90% of the treated individuals completed the 18-month regimen.
• No cases of active tuberculosis were observed among the treated groups during the follow-up period.
• The control groups experienced 9 cases of active TB, indicating an annual risk of 1.8 per 1000.

Conclusions:

• Supervised, intermittent isoniazid and ethambutol therapy is highly effective in preventing the progression to active tuberculosis in individuals with inactive TB or significant tuberculin reactivity.
• This preventive strategy significantly reduces the risk of developing active TB compared to no treatment.