Incidence of TB among school-going adolescents in South India
Abstract
Background
Tuberculosis (TB)
incidence data in vaccine target populations, particularly
adolescents, are important for designing and powering vaccine
clinical trials. Little is known about the incidence of
tuberculosis among adolescents in India. The objective of
current study is to estimate the incidence of pulmonary
tuberculosis (PTB) disease among adolescents attending school in
South India using two different surveillance methods (active and
passive) and to compare the incidence between the two groups.
Methods
The study was a prospective
cohort study with a 2-year follow-up period. The study was
conducted in Palamaner, Chittoor District of Andhra Pradesh,
South India from February 2007 to July 2010. A random sampling
procedure was used to select a subset of schools to enable
approximately 8000 subjects to be available for randomization in
the study. A stratified randomization procedure was used to
assign the selected schools to either active or passive
surveillance. Participants who met the criteria for being
exposed to TB were referred to the diagnostic ward for pulmonary
tuberculosis confirmation. A total number of 3441 males and 3202
females between the ages 11 and less than 18 years were enrolled
into the study.
Results
Of the 3102 participants in
the active surveillance group, four subjects were diagnosed with
definite tuberculosis, four subjects with probable tuberculosis,
and 71 subjects had non-tuberculous Mycobacteria (NTM) isolated
from their sputum. Of the 3541 participants in the passive
surveillance group, four subjects were diagnosed with definite
tuberculosis, two subjects with probable tuberculosis, and 48
subjects had non-tuberculosis Mycobacteria isolated from their
sputum. The incidence of definite + probable TB
was 147.60 / 100,000 person years in the active surveillance
group and 87 / 100,000 person years in the passive surveillance
group.
Conclusion
The incidence of
pulmonary tuberculosis among adolescents in our study is lower
than similar studies conducted in South Africa and Eastern
Uganda – countries with a higher incidence of tuberculosis
and human immunodeficiency virus (HIV) than India. The study
data will inform sample design for vaccine efficacy trials among
adolescents in India.
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Source:
BMC Public Health
