|EFFECT ON TUBERCULIN ALLERGY OF TUBERCULIN TESTS
GIVEN 18 MONTHS EARLIER
|Raj Narain, GD Gothi, KT Ganapathy & CV Shyama
Sunder: Indian J Med Res 1979, 69, 886-92.
Enhancing effect of tuberculin allergy as a result
of repeat tests with 1 TU RT 23 on groups tested with I TU, 20 TU
and placebo was studied by random allocation among population not
vaccinated with BCG in 8 villages. In all, 2357 persons were tested
with 1 TU and 759 with normal saline at first round. Based on testing
at three rounds the study population could be divided into eight
different groups and were labelled with alphabets 'a' to 'h' having
been tested once, twice or thrice. The groups 'a', 'c', 'e' &
g' were tested at 2 months, round two with 1 TU RT 23 and
remaining half were not tested. However, all available persons in
the 8 groups were retested at the third round, 18 months after the
initial test. Thus, eight groups cannot be treated as independent
samples but representative of the whole population.
The study did not show enhancing effect due to
previous tuberculin test with 1 TU alone among groups tested once,
twice or thrice after an interval of 18 months. Part of population
was tested with 20 TU at round one; boosting effect was seen at
2 months when test was repeated. However, it was not seen after
18 months but when exactly the boosting effect disappeared was not
known. Thus, there was no increase in reaction even among those
who were tested with a higher dose of 20 TU earlier after 18 months.
The groups provided the largest number for comparison between tested
and the control groups. It is inferred from the study that boosting
with high dose or repeat tests with the same dose does not persist
after 18 months. Hence, for classifying positive tuberculin reactors,
no correction is required to the same individuals/population after
an interval of 18 months or more, as no boosting effect after 18
months has been observed, on the basis of this analysis.
|KEY WORDS: TUBERCULIN TEST, TUBERCULIN ALLERGY,
|ROLE OF TUBERCULIN TEST IN SURVEILLANCE OF TUBERCULOSIS
|MS Krishna Murthy, AN Shashidhara, R Channabasavaiah,
RV Kale, & J Chakravarty: Proceed of Indo US Workshop on major
advances in TB Research, Madras, 4-7 Dec 1989, 111-17.
The National Tuberculosis Control Programme is
in operation since 1962, and its quantitative achievement is being
monitored indirectly through records and reports received from District
Tuberculosis Centres. For direct evidence of impact of the programme,
tuberculin surveys are useful in reflecting the recent epidemiological
situations prevailing in the area. Tuberculosis being a disease
of secular nature, a periodic follow up with five years (arbitrary)
interval may be preferred over the continuous follow up, for finding
the trend of tuberculosis situations in an area.
Keeping in view the importance of tuberculin surveys,
National TB Institute (NTI) has evolved a surveillance system which
can be adopted by any state in India. The state teams can be trained
at NTI in registering population, tuberculin testing & reading,
so as to carry out the surveillance in their respective areas. It
is essential to create a central organisation for surveillance of
tuberculosis using the tuberculin test. The centre would be responsible
for technical & administrative support and monitoring. NTI could
provide technical expertise in formulating the surveillance system,
a training methodology and an in service training to the designated
|KEY WORDS: SURVEILLANCE, TUBERCULIN TEST, TREND,
|ON CONDUCTING TUBERCULOSIS SURVEYS
|National Tuberculosis Institute, Bangalore-3: NTI
Newsletter 1990, 26, 25-27.
A methodology in brief about conducting Classical
Tuberculosis Sample Survey and Tuberculosis Surveillance is given
I. CLASSICAL TUBERCULOSIS SAMPLE SURVEY
A tuberculosis prevalence survey to measure the problem of tuberculosis
in the community is a challenging assignment especially so when
it is to be conducted by an organisation not created with the specific
objectives of carrying out research work e.g., the District Tuberculosis
Centre, State Tuberculosis Centre, etc. However, following procedure
is described in brief: (1) Selection of district for the study,
(2) Collection of basic data like size and distribution of population,
number of towns and villages, (3) Selection of sample population
for survey by valid statistical methods, (4) Census enumeration
of study population by trained census takers - preparation of cards
for all the individuals, (5) Tuberculin testing & reading of
all subjects under study, (6) BCG scar survey, (7) X- ray examination
of the eligible population (> 10 years or > 15 years). Interpretation
of X-rays by standard readers, (8) Collection of sputum from chest
symptomatics and X-ray abnormal individuals, (9) Transportation
of sputum to central laboratory (necessary precaution to be taken
during storing and transportation), (10) Sputum to be examined by
trained staff, (11) Compilation, analysis and interpretation of
data. Number of working teams with full complement of staff depends
upon the size of the study population and the time frame of the
study. An average survey team may have the following personnel on
its strength: Medical Officer - One, Census Takers - Three, Tuberculin
Tester & Reader (one each) - Two, Lab Technician - One, Lab
Asst. - One, X-ray Technician. - One, Dark room attender - One.
Equipment required: Mobile X-ray unit - mounted on a jeep along
with the generator mounted on another jeep, Laboratory infrastructure,
Vehicles preferably jeep.
Apart from the above, the team may need part time
assistance of a Statistician and a few Statistical Computers. In
case a state is interested to carry out an epidemiological survey,
it may need to create the above infrastructure. Once arranged, it
may request the National TB Institute (NTI) to train the required
staff on standard survey techniques under field situations which
is very essential.
II. TUBERCULOSIS SURVEILLANCE
In contrast to the more complex methodology involved in a classical
survey described above, an alternative, much simpler and indirect
method to assess the problem of tuberculosis in the community is
by finding out the infection rate, through tuberculin surveys. It
may be possible to estimate the prevalence of sputum smear positive
disease from infection rate. Such survey is conducted by subjecting
the age-specific unvaccinated population to tuberculin test periodically.
For carrying out the work, one to two teams composed of three to
four properly trained tuberculin testers and readers are needed
along with at least two vehicles and a standby vehicle per team.
Budgetary support for petrol, travelling and daily allowance of
staff, and for minor miscellaneous expenditure like stationery,
spirit, etc., may be required to be provided. Training could be
imparted to such personnel at NTI and their services utilised exclusively
for carrying out tuberculin surveys as a regular ongoing surveillance
activity. If this methodology is found suitable, one may take action
to create posts of tuberculin testers and readers in suitable scales
and draft them for training in tuberculin survey methodology. The
Institute will be happy to train the required personnel for the
purpose, as well as analyse the data so collected for use by the
|KEY WORDS: CLASSICAL SURVEY, SURVEILLANCE, TUBERCULIN
TEST, ASSESSMENT, METHODOLOGY.
|TUBERCULIN TESTING IN THE COMMUNITY THROUGH GENERAL
HEALTH SERVICES IN PREPARATION FOR TUBERCULOSIS SURVEILLANCE - A STUDY
|K Chaudhuri, MS Krishna Murthy, AN Shashidhara, R Channabasavaiah,
TR Sreenivas & AK Chakraborty: Indian J TB 1991, 38, 131-37.
A study was conducted in 1983-84 by the National
TB Institute (NTI) in the districts of Dharmapuri (Tamil Nadu) &
Ananthapur (Andhra Pradesh). Thirteen health personnel were trained
in census taking, tuberculin testing & reading and data keeping
etc., at the NTI according to the standard methodology. The trainees
were repeatedly assessed and only those who achieved a reasonably
high inter-reader correlation with the standard reader were chosen
for the field work. Field work was carried out by these health workers
and supervised by the team leaders of NTI. Children between 0-9
years were tested with 1 TU RT 23 with Tween 80 in tuberculin testing
centres specially set up in each village and the reactions were
read between 48 & 72 hours after the test. The tuberculin testing/reading
coverage was very high. Of 6702 eligible children, 5904 (97%) were
tuberculin test read.
Individual reading assessment carried out at Ananthapur
and Dharmapuri for the State Field Workers (SFWs) showed that agreement
with Standard Reader (SR) of NTI at three induration levels i.e.,
10+ mm, 14+ mm and 18+ mm were very high. The demarcation line between
infected and uninfected appeared to be about 18 mm. In Ananthapur,
the agreement at 18+ mm was 99% and at Dharmapuri it was 100% for
SFW, and 98.4% for SFW-2. The estimates of prevalence rate of infection
were 9.3% - SFW V/s 9.7% - SR at Anantapur, 5.2% - SFW V/s 5.2%
- SR and 7.2% - SFW.2 V/s 7.2% - SR at Dharmapuri. The study further
showed that it was possible to train general health workers, within
a period of 3 months to attain a high level of efficiency. The general
health services can successfully organise on their own a programme
of tuberculin testing in the community with proper liaison and supervision
by some nodal agency. The training and field supervision responsibilities
may be shouldered initially by NTI or another suitable organisation,
till these nodal agencies come up.
|KEY WORDS: SURVEILLANCE, TUBERCULIN TEST, HEALTH
SERVICES, FEASIBILITY, COMMUNITY.
| TUBERCULIN TESTING IN A PARTLY BCG VACCINATED POPULATION
|National Tuberculosis Institute, Bangalore: Indian
J TB 1992, 39, 149-58.
To obtain precise information for computing the
indices of tuberculosis situation in a community, with passage of
time, reliance has been placed on tuberculosis infection rates obtained
by carrying out tuberculin surveys. In most developing countries,
covered extensively by BCG vaccination without prior tuberculin
testing, the tuberculin test has problems of interpretation for
demarcating the infected persons from the uninfected. To overcome
the problem, therefore, the test results are analysed among persons
who do not show a BCG scar and are, thus, considered as normal population.
In this paper, an attempt is made to show that BCG vaccination not
always lead to the formation of a scar, and also that the scar resulting
from BCG vaccination may fade away with time and the person, thus,
may be wrongly included in the unvaccinated group. It has also been
found that there is greater fading of scars in the younger age groups:
in children 0-2 years of age, upto 52% of the scars faded away within
21 months of vaccination. This proportion steadily decreased to
about 8% in the 10-14 years age group.
The implication of the finding is that the demarcation line between
uninfected and infected persons may require to be shifted from survey
to survey, based on the distributions among the 'no scar' population.
Moreover, in a totally vaccinated community, the differences of
reactions may provide the answer to the problem of identifying the
newly infected persons.
|KEY WORDS: TUBERCULIN TEST, BCG SCAR, INFECTION,