| CHANGES IN THE PREVALENCE RATES OF INFECTION IN
YOUNGER AGE GROUPS IN A RURAL POPULATION OF BANGALORE DISTRICT OVER
A PERIOD OF 5 YEARS
|AG Kurthkoti & Hardan Singh: NTI Newsletter
1985, 21, 28-40.
The utility of repeated estimates of prevalence
rates of infection in children as a tool for surveillance in tuberculosis
is now well recognized. Two prevalence surveys at an interval of
5 years were conducted by National Tuberculosis Institute, Bangalore,
with the main objective of studying changes in prevalence rate of
infection among children in the age group of 0-9 years. A total
population of 42,343 residing in 90 randomly selected villages of
Doddaballapur taluk, Bangalore, were registered; of them, 12,535
were children in the age group of 0-9 years. Children were further
classified into two sub groups 0-4 and 5-9 years, with or without
BCG scars. The unvaccinated children in these two age groups formed
the study population.
The population in the study area during the 2nd
repeat survey was similar to that of first survey with regard to
age, sex distribution, except that a growth rate of 1.1% per year
was registered. The BCG scar rate, among children in the age group
0-4, 5-9 years, was 8% & 39% respectively at survey I. All the
unvaccinated children below 10 years were given tuberculin test
with 1 TU PPD RT 23 and reactions were read 72 to 96 hours after
tuberculin testing. In the first survey, level of demarcation to
classify the infected children was 10 mm and above, while in II
survey it was 12 mm and above. It was observed that the prevalence
rate of infection from I survey to II survey was not altered (2.58%
& 2.46%) in the 0-4 years of age, while there was an increase
in the rate from 8.93% to 12.3% in 5-9 years of age in the II survey.
The increase in the infection rate could be attributed to the rising
trend of infection, over reading by tuberculin-readers', skills
of both tuberculin tester and reader, boosting of tuberculin reaction
or scarless BCG vaccination. In conclusion, the study of changes
in the prevalence rate of infection in the younger age group is
simple, cheap, less time consuming. The data can be used for calculating
annual risk of infection as well trend of transmission of infection.
|KEY WORDS: TREND, RISK OF INFECTION, PREVALENCE,
SURVEILLANCE, RURAL COMMUNITY.