|ENHANCING OF TUBERCULIN ALLERGY BY PREVIOUS TUBERCULIN
|Raj Narain, SS Nair, G Ramanatha Rao, P Chandrasekhar
& Pyare Lal: Indian J TB 1966, 13, 43-56; Tables i-vii.
Tuberculin tests repeated after an interval of
time, at a different site have been reported to elicit reactions
larger than the first test. A study was undertaken where reactors
of 13mm or less to 1 TU have been tested with 20TU for the study
of low grade reactions. Study was carried out in a previously untested
and unvaccinated rural population (Longitudinal Survey), where only
about 25% of the population showed 14mm or more to 1 TU and the
remaining about 60% showed 10mm or larger reactions to 20 TU. These
results confirm the high prevalence of non-specific allergy in the
It was found that a tuberculin test does enhance
the allergy elicited by a subsequent test. The enhancing effect
is associated with the initial allergy i,e., 8-13mm to 1 TU tuberculin,
especially those elicited by a 20 TU test, increase being almost
confined to those with 10mm and larger reactions to 20 TU. The enhancing
effect increases with increase in age especially among those with
10mm or bigger reactions to 20 TU. It is possible that the enhancing
effect is more in communities with high prevalence of non-specific
|KEY WORDS: TUBERCULIN REACTION, ENHANCEMENT,
NON SPECIFIC ALLERGY, INFECTION, M.TUBERCULOSIS, NTM.
|FIVE YEAR INCIDENCE OF TUBERCULOSIS AND CRUDE MORTALITY
IN RELATION TO NON SPECIFIC TUBERCULIN SENSITIVITY
|GD Gothi, SS Nair, AK Chakraborty & KT Ganapathy:
Indian J TB 1976, 23, 58-63.
The study was undertaken in a sample of 103 villages
of 3 sub-divisions of Bangalore district as a part of the 5 year
study of epidemiology of tuberculosis between 1961-68. The follow
ups were done at 1.5, 3 & 5 years after the first survey.
The entire population was offered tuberculin test with 1 TU RT 23,
a second test with 20 TU RT 23 to those persons who were having
reactions of 0-13 mm to 1 TU. All aged 5 years or more were offered
70mm photofluorograms at each survey. Two specimens of sputum were
collected from persons having abnormal X-ray shadows for examination
of tubercle bacilli. Procedures were uniform at each survey. The
population was divided into three groups on the basis of their tuberculin
reactions: (a) reactors to 1 TU (infected with M.tuberculosis),
b) non-reactors to 1 TU but reactors to 20 TU (infected with atypical
mycobacteria), c) non-reactors to both 1 TU & 20 TU (not infected
with either M.tuberculosis or other mycobacteria). Incidence of
disease and crude mortality were studied separately among these
The five year incidence of culture positive disease
was the highest among 1 TU reactors and the least among reactors
to 20 TU. In the younger age group (5-14 years) the five year incidence
of culture positive disease among reactors to 20 TU was significantly
lower compared with that among 20 TU non-reactors. The reduction
of incidence of culture positive cases in the former group over
that in the latter was 75% for culture positive cases and 61% for
combined culture positive and negative disease. As regards crude
mortality, the overall rate was significantly lower among 20 TU
reactors compared with non-reactors. Even if the significance of
the finding on crude mortality is debatable, it could be concluded
that non-specific infection provides some protection against development
of tuberculosis, at least in younger age groups.
|KEY WORDS: INCIDENCE, DISEASE, MORTALITY, NTM,
|PREVALENCE OF NON-SPECIFIC SENSITIVITY TO TUBERCULIN
IN A SOUTH INDIAN RURAL POPULATION
|AK Chakraborty, KT Ganapathy, SS Nair & Kul Bhushan:
Indian J Med Res 1976, 64, 639-51.
The data from a tuberculosis prevalence survey
carried out in three taluks of Bangalore district in south India
during 1961-68 were analysed to study (i) the prevalence of non-specific
sensitivity in the community i.e., prevalence of infection with
mycobacteria other than M.tuberculosis, as found by testing the
population with tuberculin RT 23 of a lower strength (1 TU) and
higher strength (20 TU), both with Tween 80 and (ii) additional
boosting if any, resulting from testing with higher dose of tuberculin,
immediately following a test with 1 TU RT 23.
The level of demarcation between infected and uninfected
with 1 TU was 0-9 mm induration size and this negative group tested
with 20 TU dose induration of 8 mm or more was considered positive.
Prevalence of infection with M.tuberculosis in the community were
2.1% in 0-4 years, 7.9% in 5-9 years, 16.5% in 10-14 years, 33.2%
in 15-24 years and overall 14.5% in 0-24 years of age group. Infection
rate with other mycobacteria were 12.9%, 44.9%, 66.2%, 62.4% and
45.7% respectively in the above stated different age groups.
Testing the population with 20 TU RT 23 following
a 1 TU test was found not to boost the tuberculin reactions over
that observed on a single test with 1 TU only.
|KEY WORDS: NTM, PREVALENCE, INFECTION, BOOSTING,
TUBERCULIN REACTION, RURAL POPULATION.