Decrease in risk of tuberculosis infection despite increase in tuberculosis among young adults in urban Vietnam.
OBJECTIVE
To assess whether the increase in tuberculosis (TB) notification rates among young adults in Vietnam reflects increased transmission in the population at large.


METHODS
Trends of case notification rates of new smear-positive TB were calculated from routinely reported data of district TB units over the period 1996-2005. Results from repeated tuberculin surveys among children aged 6-9 years were obtained to calculate the trend in annual risk of TB infection (ARTI).


RESULTS
From 1996 to 2006, notification rates in the age group 15-24 years increased by 4.3% per year, and more so in highly urbanised (6.7%) than in rural districts (1.7%). The ARTI in urban districts declined from 2.4% in 1992 to 1.2% in 1998 and 0.9% in 2005. In rural districts, the ARTI increased from 0.7% in 1991 to 1.2% in 1997, and then declined to 0.9% in 2006.


CONCLUSIONS
The increase in TB notification rates among young adults in Ho Chi Minh Province is accompanied by a decrease in ARTI in children. This suggests that the trend in TB notification among young adults reflects increased rates of progression from infection to disease and/or increased transmission within this age group, rather than increased transmission in the population at large.
Pham Ngoc Thach Tuberculosis and Lung Disease Hospital, Ho Chi Minh City, Ho Chi Minh Province, Vietnam.
T N
TN
Buu
H T
HT
Quy
N C
NC
Qui
N T N
NT
Lan
D N
DN
Sy
F G J
FG
Cobelens
D000293:Adolescent; D017677:Age Distribution; D002648:Child; D018563:Disease Notification / Q000706:statistics & numerical data; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D012423:Rural Health; D013997:Time Factors; D014374:Tuberculin Test; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology* / Q000635:transmission; D014504:Urban Health / Q000639:trends*; D014744:Vietnam / Q000453:epidemiology; D055815:Young Adult