|SIZE & EXTENT OF TB PROBLEM IN URBAN & RURAL
|Raj Narain: Indian J TB 1962, 9, 147-50 & also
in Proceed Natl TB & Chest Dis Workers Conf 1962, 155-68.
The aim of modern Public Health Programmes, is
a reduction in the total amount of disease in the community. The
unit for treatment and cure is not an individual but a sick community.
With this new aim, it becomes essential to know the size and extent
of tuberculosis in the community as it will be helpful not for purposes
of planning only but essentially for the assessment of their effect
on the problem. An attempt is made to review the important features
of the available knowledge about infection, morbidity and mortality
through various surveys. (i) Prevalence of Infection: Tuberculosis
infection is widespread in both urban and rural areas of almost
all parts of the country. Nearly 40% of the population are infected.
To avoid the effect of non- specific allergy and get a more reliable
demarcation, tuberculin reactions of 14mm and more were considered
as positive by National Tuberculosis Institute. (ii) Prevalence
of morbidity: The prevalence of radiologically active tuberculosis
in the population is likely to be 1.5%, Prevalence of bacteriologically
confirmed diseases is 0.4%. Based on single sample of sputum examination,
the prevalence of infectious cases in the country is probably an
under estimate. About two million are infectious at any one point
of time. (iii) Mortality: Deaths from tuberculosis in the
country is not definitely known. The impression of clinicians that
death due to tuberculosis have fallen sharply may not be true. Half
a million deaths will appear an underestimate. About 250 per 1,00,000
persons i.e., one million deaths due to tuberculosis per year seems
to be a reasonable estimate. (iv) Bovine Tuberculosis: Only
a few cases in man caused by the bovine tubercle bacillus have been
reported although 2.75% to 25% of cattle have been found tuberculin
To put in a nut shell, the problem of tuberculosis
in India is a gigantic one and our means of fighting it with the
single tool of BCG, do not even touch the fringe of the problem.
|KEY WORDS: INFECTION, SUSPECT CASE, CASE, MORTALITY,
|FATE OF CASES DIAGNOSED IN A SURVEY
|Raj Narain, G Ramanatha Rao, G Chandrasekhar &
Pyare Lal: Proceed Natl TB & Chest Dis Workers Conf,
The report describes the changes that occurred
during second survey carried out after an interval of one and half
years in the cases diagnosed at the first survey done during 1961-62
from among a total population of about 62,000 in 119 villages in
Bangalore District. It was observed that (1) Of the 62 sputum smear
positive cases also having suggestive chest X-ray shadows, 34% had
died, 35% were sputum positive and 31% had become culture negative
after 1½ years. Of the 10 smear positive cases who were X-ray
normal, non-e was culture positive at the start and 7 were negative
by culture and smear after 1½ years. Of the 67 scanty smear
positive cases (1 to 3 bacilli seen), only 3 were sputum positive,
10 were having X-ray shadows and half were tuberculin negative after
1½ years. (2) Of the 88 culture only positive cases (20 or
more colonies and with X-ray evidence of disease) 31% had died and
47% continued to be sputum positive after 1½ years. A much
smaller proportion of these changes occurred among culture positive
cases with less than 20 colonies. (3) There were 457 persons having
radiologically active tuberculosis on the basis of interpretation
of a single X-ray picture by two independent readers but whose sputum
were negative for AFB (suspect cases). Of these, 38% were tuberculin
negative also. Of those suspect cases who were tuberculin positive,
9% become sputum positive after 1½ years, while only 2% of
the tuberculin negative suspect cases became sputum positive.
It is concluded that there is a lot of variation
in fate among the different categories of cases of pulmonary tuberculosis.
Further, attention has been drawn to the possibility of self healing
in about 30% of the bacillary cases after 1½ years.
|KEY WORDS: FATE, CASE, SUSPECT CASE, NATURAL
|DISTRIBUTION OF TUBERCULOUS INFECTION AND DISEASE
IN CLUSTERS OF RURAL HOUSEHOLDS
|SS Nair, G Ramanatha Rao & P Chandrasekhar: Indian
J TB 1971, 18, 3-9.
Data from 62 randomly selected villages in a district
of south India, which formed part of a prevalence survey carried
out by the National Tuberculosis Institute, Bangalore, during 1960-61,
has been made use of. The survey covered 29,813 persons in 5,266
households. There were 70 cases with bacilli demonstrable either
in smear or culture and 300 suspect cases. Using the village map
(prepared by survey staff), case clusters were formed
first, with each case household as nucleus and adjacent households
within a maximum distance of about 20 meters on either side of the
case households. Households closest to the nucleus household on
either side have been called as 1st neighbourhood and those coming
next in proximity on either side as a 2nd neighbourhood and so on.
The case household and its four neighbourhood together was called
a cluster. If another case household was found within 4th neighbourhood
of the first case the cluster was extended by including the 4th
neighbourhood of the new case also. Such clusters were called composite
case clusters and clusters with only one case household as simple
case clusters. Similarly, suspect case clusters were formed and
differentiated as simple suspect clusters or composite suspect clusters.
Further, to serve as a control group, non-case clusters were constituted
from a systematic sample of 10% households that were not included
in case or suspect case clusters.
Out of 60 case clusters formed, only 7 have multiple
cases showing that there was no evidence of high concentration of
disease in case clusters. While the percentage of child contacts
(0-14 years) infected was considerably higher in case clusters (25.8%),
there was not much difference between suspect case clusters (14.9%)
and non-case clusters (9.8%). Similarly, there was not much difference
between simple and composite clusters. Infection among child contacts
was higher in case households as compared to their neighbourhoods.
To get some idea of the zone of influence of a case or suspect case,
prevalence of infection was studied for 10 neighbourhoods, in simple
clusters to avoid the influence of multiple cases. It appeared that
the zone of influence of a case may extend at least upto the 10th
neighbourhood. It was also noted that there was very little difference
between zones of influence of suspect cases and non-cases. Case
clusters in which the nucleus case had shown activity of lung lesion
(evident on X-ray reading) or had cough showed significantly higher
infection among child contacts. Clusters around cases positive on
both smear and culture did not show higher infection than those
around cases positive on culture only. (This may be due to sputum
examination of single specimen only).
Out of the total infected persons in the community,
only 2% were in case households and 7% in suspect case households,
over 90% being in non-case households. The zone of influence of
a case extending at least upto the 10th neighbourhood and the overlapping
of such zones of influence of cases, present and past, seems to
be the most probable explanation for the wide scatter of infection
in the community. Prevalence of infection among child contacts was
definitely higher in case clusters. But, the significance of this
could be understood only from a study of the incidence of disease
during subsequent years in different types of clusters. It is significant
that only 10% of the total infected persons in the community were
found in case clusters. The case yield in general population, cluster
contacts, household contacts and symptomatics attending general
health institutions have been also compared. The case yield in the
last group (10%) is much higher than the case yield from both types
of contacts (0.7% and 0.6%) which where only slightly higher than
the case yield from the general population (0.4%).
|KEYWORDS: RURAL, HOUSEHOLDS, CLUSTERS, CASE,
SUSPECT CASE, CONTACT, PREVALENCE, INFECTION, DISEASE, SURVEY.
|SOME ASPECTS OF CHANGES IN RURAL POPULATION AND
FATE OF TB CASES AFTER AN INTERVAL OF TWELVE YEARS
|MS Krishnamurthy, KR Rangaswamy, AN Shashidhara &
GC Banerjee: NTI Newsletter, 1974, 11, 1-7.
During second epidemiological survey carried out
in 1972-73, special efforts were made in 21 of 62 villages belonging
to first survey (1961-62) to study the demographic changes and fate
of TB cases after an interval of 12 years.
The findings were: The increase of dejure population
was about 20% over a period of 12 years i.e., an annual increase
of 1.7%. The age structure had altered mainly due to significant
increase in the age group 60 years and above 51% to 64% indicating
aging of population. The loss of original population after 12 years
was 44%, of which 33% was due to migration and 11% due to death.
The overall migration was more among females. The migration rate
was higher in younger age group, being highest in 10-19 years (49%),
next in 0-9 years (38%). Thus, overall migration in 0-19 years was
43%. The death rate was highest in 60 years and above (58%). It
varied from 4-9% in age group 0-39 years. Original population available
after 12 years for re-examination was 56%. Distribution in different
age groups were; 0-9yr = 57%, 10-19yrs = 47%, 20-49yrs = 66%, 50-59yrs
= 44%, 60yrs and more = 28%.
Out of 88 X-ray suspect cases of earlier survey,
87 could be identified and present status of 72 were known. Of them,
16 were normal, 12 and 4 found to be suspect cases and bacillary
cases respectively and 40 had died. Of the remaining fifteen, 11
migrated and 4 not examined. Out of 14 bacillary cases, 13 could
be identified. Of them, 3 were sputum negatives (2 normal and 1
suspect case) 9 had died and 1 migrated.
|KEYWORDS: FATE, CASE, SUSPECT CASE, MORTALITY,
MIGRATION, RURAL POPULATION, DEMOGRAPHIC CHANGES, SURVEY.
|SIGNIFICANCE OF PATIENTS WITH X-RAY EVIDENCE OF
ACTIVE TUBERCULOSIS NOT BACTERIOLOGICALLY CONFIRMED
|SS Nair: Indian J TB, 1974, 21, 3-5.
Available data from longitudinal study (1961-68)
from several different situations have been reviewed to understand
the significance of patients showing radiological evidence of pulmonary
tuberculosis without bacteriological confirmation. SITUATION IN
GENERAL POPULATION: Few of the smear negative but X-ray active tuberculous
patients (suspect cases) found in a survey of rural population done
by National TB Institute, were culture positive (7-10%). On follow
up for 18 months, only 3% of them became culture positive under
conditions where intervention with specific treatment was absent
or minimum. It is thus concluded that most of the cases diagnosed
as active tuberculosis on the basis of single X-ray are not likely
to be cases of tuberculosis. SITUATION AMONG SYMPTOMATICS ATTENDING
HEALTH INSTITUTIONS: Data from the State TB Demonstration and Training
Centres (STDTC) and the District Tuberculosis Programmes (DTP) have
been presented. The New Delhi Tuberculosis Centre records (1970)
show that only 27% of microscopy negative radiologically positive
patients were confirmed on culture. For Bangalore and Agra STDTC,
the proportions so confirmed were 20% and 25% respectively. It has
been calculated that in the DTPs, not more than 30% of the microscopy
negative radiologically positive patients could be the real cases
of tuberculosis. In the DTP situation not more than 10% of the suspect
cases may develop bacteriologically confirmed disease. Thus, not
many of the suspect cases could be real cases of tuberculosis either
on the basis of confirmation by culture or on the basis of development
of bacteriologically positive disease in future.
Are the cases diagnosed early by
radiology? The hypothesis that X-ray discovers cases in the
early stages has not yet been put to a scientific test. Further,
the large differences even between experienced readers in interpreting
X-ray shadows, render the method of X-ray diagnosis questionable.
Is anti tuberculosis treatment of suspect cases warranted?
The possible advantage of considering treatment of suspect cases
as chemoprophylaxis has to be weighed against conservation of resources
for treatment of infectious cases and the possible harmful effects
of anti TB drugs to persons who are not suffering from tuberculosis.
|KEY WORDS: CHEST SYMPTOMATICS, RURAL COIMMUNITY,
|INTERPRETATION OF PHOTOFLUOROGRAMS OF ACTIVE PULMONARY
TB PATIENTS FOUND IN EPIDEMIOLOGICAL SURVEY AND THEIR FIVE YEAR FATE
|GD Gothi, AK Chakraborty & GC Banerjee: Indian
J TB 1974, 21, 90-97.
In this study the material from Five year
study of Epidemiology of Tuberculosis (1961-68) has been analysed
to find out an improved method of interpretation of chest X-rays
to get accurate estimation of prevalence of suspects
in the community. The population of a random sample of 119 villages
from the three taluks of Bangalore district was surveyed four times
with intervals of 1½ to 2 years by tuberculin testing, 70mm
chest photofluorography and sputum bacteriology. Out of 45,434 persons
X-rayed during the first survey, 590 were read as active pulmonary
tuberculosis on the basis of single picture interpretation by two
independent readers. Of them, 460 being sputum culture negative
were classified as initial suspects and these were reviewed
in this study by the panel of three readers together by the method
of joint reading. The interpretation was done comparing
the serial X-rays of individuals taken at intervals along with other
available examination results and personal data. Out of 460 initial
suspects only 110 (23.9%) were confirmed as suspects,
the remaining were judged as non-tuberculous and/or inactive tuberculous
(62.2%) and normals (13.9%).
Fates on five year follow up were compared between
85 confirmed suspects and 385 initial suspects.
The mortality and sputum positive status were found more among the
former group i.e., 23.5 and 25.5 and 14% and 7.2% respectively.
Radiologically, 48.7% of the confirmed suspects and only 10% of
the initial suspects could be classified as suspects at 5th year
follow up. Incidence of bacillary disease among the confirmed suspects
was also found higher. On the basis of joint reading
and five year follow up study, the limitations of single picture
interpretation resulting in considerable over diagnosis were clearly
seen. The comparative reading of serial X-rays along with other
examination results did help in the better assessment of etiology
and activity status of disease. Of the X-rays read as non-tuberculous
and inactive tuberculous when reviewed by joint reading
method, about 67 more suspects could be added. Even then the estimates
of prevalence of suspects based on single film interpretation
which are widely used in India appear to be about 3 times the actual
|KEY WORDS: FATE, SUSPECT CASE, X-RAY, JOINT
READING, SINGLE PICTURE, OVER DIAGNOSIS.
|PREVALENCE AND INCIDENCE OF SPUTUM NEGATIVE ACTIVE
PULMONARY TUBERCULOSIS AND FATE OF PULMONARY RADIOLOGICAL ABNORMALITIES
FOUND IN A RURAL POPULATION
|GD Gothi, AK Chakraborty, VV Krishnamurthy & GC
Banerjee: Indian J TB 1978, 25, 122-31.
A study was carried out mainly to find out the
prevalence and incidence of sputum negative active pulmonary tuberculosis
(suspect cases) among 35,876 persons aged 5 years and above in rural
areas of Bangalore district during 1968-72. Two surveys (I &
II) at an interval of 3 months, succeeded by a follow up examination
of the X-ray abnormals of the earlier surveys, were conducted in
the same villages. Examinations at each survey consisted of tuberculin
test, X-ray and sputum examinations. X-rays were interpreted individually
at the time of each survey by single picture interpretation method
and subsequently by Joint Parallel Reading (JPR) method to
arrive to a diagnosis. In the JPR method X-ray readings and their
comparison was done by a panel of three X-ray readers with full
knowledge of age, sex, result of sputum examination and tuberculin
test of each person with chest abnormality at any of the three surveys.
On a single picture interpretation the overall
prevalence rate of suspect disease was found to be 5.4 per thousand
at I survey and 4.59 per thousand at II survey. There was no significant
difference in the overall age and sex specific prevalence rates
of suspect disease between I & II surveys. Incidence of suspect
disease at the end of 3 months was 2.24 per thousand. By JPR method
the prevalence rates of suspect disease was 3.2 per thousand at
I survey and 3.6 per thousand at II survey. The prevalence rates
by single picture method were overestimated to the extent of 38%
at I survey and 19% at II survey when compared with those found
by JPR method. At I survey prevalence rates on JPR method was significantly
lower than by single picture method. This was not so at II survey.
Similarly, incidence rate of 0.2 per thousand of suspect disease
on JPR was about 1/10th of that found by single picture method.
The incidence of bacteriologically positive cases
in 6 months from among suspect cases on JPR was found to be 28%.
Majority (76%) of non-tuberculous or inactive tuberculous shadows
continued to remain as such after 6 months and about a quarter (23%)
became normal. Incidence of bacteriologically positive cases from
this group was minimal. Of 19,640 persons with normal X-rays 134
(0.7%) developed new shadows in 3 months; 103 (0.5%) cleared after
2-12 weeks (fleeting shadows). Mis-interpretation of the latter
as active tuberculous may falsely boost the estimates of suspect
disease to the extent of about 5%.
|KEY WORDS: SUSPECT CASE, PREVALENCE, INCIDENCE,
RURAL POPULATION, FATE.
|PREVALENCE, INCIDENCE AND FATE OF SUSPECT CASES
OF TUBERCULOSIS IN A RURAL POPULATION OF SOUTH INDIA
|VV Krishna Murthy: NTI Newsletter 1982, 19, 75-80.
The data from a longitudinal survey conducted in
Bangalore district from 1961-1968 by National Tuberculosis Institute
was analysed to find out the prevalence, incidence and fate
of suspect cases. In brief, the survey was conducted in 119
randomly selected villages in three taluks of Bangalore district
and repeated within the next five years. At each survey, eligible
population was subjected to tuberculin, X-ray & sputum smear
and culture examinations.
The overall prevalence rate of suspect cases among
persons aged five years and more was 1.06% at I survey, 0.68%, 0.49%
and 0.43% at II, III and IV survey respectively. In males, the prevalence
rate was 1.19% at I survey & 0.62% at IV survey corresponding
figures for females were 0.94% and 0.24% respectively. A decline
of prevalence of suspect cases from 1.06% at I survey to 0.43% at
IV survey was observed. The overall incidence of suspect cases was
0.16% between I & II surveys, 0.10% between II & III, and
0.06% between III & IV surveys. The overall as well as age specific
annual incidence rates between III & IV surveys were significantly
less than that between I & II surveys. At all the three intervals
the incidence increased with the age. Incidence of suspect cases
in males was more than that in females. Change in disease status
over a period of time is termed as "fate". The
disease status was classified as (i) cure (ii) continued to be suspect
case (iii) converted into bacillary cases and (iv) dead. The percentage
of cure (51.9%, 53.2% and 50.3%) and conversion into bacillary cases(7.2%,5.8%
and 5.4%) were almost the same at all the three intervals. But the
percentage of those who remained suspect cases reduced from 33.5%
at the end of 18 months to 17.5% at the end of 60 months. On the
other hand, the death rate increased from 7.4% at the end of 18
months to 26.8% at the end of 60 months. The decreasing trend of
continuing to be suspect cases at the rate of 10% between two observations,
appears to be corresponding to the increasing trend in the death
rate as seen from the observations made at the three intervals.
|KEY WORDS: PREVALENCE, INCIDENCE, FATE, SUSPECT
CASE, RURAL COMMUNITY, LONGITUDINAL SURVEY.