Contact screening procedures for tuberculosis in Auckland.

Area of Science:

• Public Health
• Epidemiology
• Infectious Disease Control

Background:

• Tuberculosis (TB) remains a significant global health concern.
• Contact screening is a key strategy for early detection and prevention of TB transmission.
• Understanding the yield and patterns of contact screening is crucial for optimizing public health efforts.

Purpose of the Study:

• To audit tuberculosis notifications derived from contact screening in Auckland health districts over five years.
• To identify the demographic groups and exposure types yielding the highest number of new TB cases through contact screening.
• To evaluate the effectiveness of current contact screening protocols and suggest improvements.

Main Methods:

• A retrospective audit of tuberculosis notifications over a five-year period.
• Analysis of data from three Auckland health districts.
• Categorization of notifications based on screening source, patient age, and index case infectiousness.

Main Results:

• 10.7% of all TB notifications originated from contact screening.
• The majority of cases found via contact screening were children (73.2%) under 16.
• Contacts of infectious pulmonary tuberculosis patients yielded the most cases (78.8%), with a particularly high infection rate (23.8%) among close child contacts compared to casual contacts (1.1%).

Conclusions:

• Contact screening is highly effective in identifying infected children, particularly those with close exposure to infectious pulmonary TB.
• Current screening practices for adult contacts may be suboptimal due to focusing only on symptomatic disease and insufficient surveillance duration.
• Restricting contact screening to the highest-risk individuals, such as close contacts of infectious pulmonary TB cases, can substantially reduce workload with minimal loss of case detection.