Decrease in risk of tuberculosis infection despite increase in tuberculosis among young adults in urban Vietnam.

Area of Science:

• Epidemiology
• Public Health
• Infectious Diseases

Background:

• Tuberculosis (TB) notification rates have been increasing among young adults in Vietnam.
• Understanding the drivers of this trend is crucial for effective public health interventions.

Purpose of the Study:

• To determine if rising TB notification rates in young adults reflect increased transmission within the general population.
• To analyze trends in TB case notifications and the annual risk of TB infection (ARTI) in Vietnam.

Main Methods:

• Calculated trends in new smear-positive TB case notification rates from 1996-2005 using routine data.
• Analyzed data from repeated tuberculin surveys in children (aged 6-9 years) to assess ARTI trends.

Main Results:

• TB notification rates in the 15-24 age group increased by 4.3% annually from 1996-2006, with higher increases in urban areas.
• ARTI in urban districts declined from 2.4% (1992) to 0.9% (2005).
• ARTI in rural districts showed an initial increase followed by a decline, reaching 0.9% in 2006.

Conclusions:

• The rise in TB notifications among young adults in Ho Chi Minh Province coincided with a decrease in ARTI among children.
• This suggests that the observed TB trend is likely due to increased progression from infection to disease or heightened transmission within the young adult group.
• The findings do not support an increase in TB transmission throughout the general population.