No decrease in annual risk of tuberculosis infection in endemic area in Cape Town, South Africa

Area of Science:

• Public Health
• Infectious Disease Epidemiology
• Tuberculosis Control

Background:

• Tuberculosis (TB) remains a significant public health challenge globally and in South Africa.
• Understanding the dynamics of TB transmission is crucial for effective control strategies.
• Previous studies have highlighted the burden of TB in urban settings, necessitating ongoing surveillance.

Purpose of the Study:

• To estimate the change in annual risk of tuberculosis infection (ARTI) in two urban communities in Cape Town.
• To compare ARTI with tuberculosis notification rates and treatment outcomes.
• To assess the effectiveness of current TB control measures in these communities.

Main Methods:

• Tuberculin skin test surveys were conducted in 1998-1999 and 2005 among children aged 6-9 years.
• Annual risk of tuberculosis infection (ARTI) was calculated based on prevalence data.
• Tuberculosis notification rates and treatment outcomes were obtained from the TB register.

Main Results:

• The overall ARTI was 3.7% in 1998-1999 and increased to 4.1% in 2005.
• Pulmonary TB notification rates significantly increased from 646 to 784 per 100,000 between 1998 and 2002.
• ARTI remained stable in Ravensmead but significantly increased in Uitsig, linked to higher case rates and previously treated cases.

Conclusions:

• Tuberculosis transmission rates remain high in the studied Cape Town communities.
• Current TB control measures appear insufficient to curb transmission effectively.
• There is a critical need for enhanced strategies to control tuberculosis in these urban areas.