|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,
|SOME ASPECTS OF A TB PREVALENCE SURVEY IN A SOUTH
|Raj Narain, A Geser, MV Jambunathan & M Subramanian:
Bull WHO 1963, 29, 641-64 & Indian J TB 1963, 9, 85-116.
The objective was to establish the prevalence rates
for tuberculosis infection, radiologically active pulmonary tuberculosis
and bacteriologically confirmed diseases for different age and sex
groups. Tumkur District in Mysore State consisting of 2,392 villages,
10 towns of was selected for the study. The district headquarter
town Tumkur was excluded from the survey. Random sample of 62 villages
and 4 town blocks having a population of 34,746 persons constituted
the study population. All the individuals available in the registered
population were given a Mantoux test with 1 TU RT 23 with Tween
80. Longitudinal diameter of induration was read 3-4 days after
the test. At the time of tuberculin test, all persons aged 10 years
and above were offered a single 70mm photofluorogram. For each picture
read as abnormal, a spot specimen of sputum of the individual concerned
was collected at the time of reading the tuberculin test. Age and
sex distribution of infection and disease were studied.
Various parameters concerning the prevalence of
infection and disease in the community were reported. Prevalence
rate of infection in all ages and both sexes of the population was
found to be 38.3%, radiologically active tuberculosis 1.86% and
0.41% sputum positive disease. The infection and disease increased
with age; of the total diseased, half were in age group 40 years
and more and about 2/3 among males.
|KEY WORDS: SURVEY, PREVALENCE, INFECTION, DISEASE,
CASE, COMMIUNITY, RURAL, URBAN.
|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
|PREVALENCE, FATE, SOURCE AND INFECTIVITY OF RESISTANT
IN MYCOBACTERIUM TUBERCULOSIS
|Raj Narain, P Chandrasekhar, Pyare Lal and RA Satyanarayanachar:
Proceed Natl TB & Chest Dis Workers Conf, Hyderabad,
The material on resistant strains of mycobacterium
tuberculosis is derived from the longitudinal survey conducted from
1961-68 in a random sample of 133 villages of 3 taluks of Bangalore
district. About 54,000 persons aged five years or more were surveyed
3 times at an interval of 18 months, two samples of sputum were
collected from persons whose chest X-rays were judged to have abnormal
shadows. The sputum specimens were examined by direct smear and
culture and sensitivity tests were performed.
An attempt is made to study prevalence, fate, source
and infectivity of resistant mycobacterium tuberculosis in three
rounds. PREVALENCE: In the 3 rounds, 199, 194 and 176 cases
respectively yielded positive cultures; Of them, 30, 36 and 53 cases
were having resistant strains. At round III, the number of culture
positive cases has not fallen significantly, but the number of strains
resistant to INH alone has sharply increased (13, 18 & 35).
Both findings are likely to be due to the treatment with INH alone
offered at round II and also due to the fact that treatment was
taken very irregularly. FATE: Over period of 3 years, of
the cases with INH resistant strains, more than 1/3rd were dead,
1/4th continued to remain positive and resistant, and 1/4th became
culture negative. Whereas, of the cases with strains sensitive to
INH, less than 1/3rd were dead, 1/3rd became negative and the remaining
were positive, 1/2 with sensitive strains and 1/2 with resistant
strains. SOURCE OF CASES: The prevalence of cases with resistant
strains at any one round is not due to the persistence of such cases
from previous rounds but by development of new cases with such strains
at each round. INFECTIVITY: The incidence of infection among
contacts with sensitive strain was significantly more than among
the contacts of cases with resistant strain. It is inferred that
the infectivity of sensitive strains is more than that of the resistant
|KEY WORDS: M.TUBERCULOSIS, SENSITIVE STRAINS,
RESISTANT STRAINS, CASE, FATE, PREVALENCE, INFECTIVITY.
|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.
|ESTIMATION OF NUMBER OF REPEAT EXAMINATIONS REQUIRED
TO DETECT ALL TB CASES IN THE COMMUNITY
|R Rajalakshmi & SS Nair: Indian J Public Health
1976, 20, 118-21.
Examination of only one sputum sample cannot detect
all the sputum positive cases in the community. To obtain better
estimates of the prevalence of bacteriologically confirmed disease
in the community, a study was conducted to find out the additional
yield of cases through collection and examination of eight sputum
specimens and also in order to work out correction factors for
estimates based on one or two sputum samples, as collecting multiple
sputa is very difficult. The study was carried out in 77 villages
in Nelamangala Taluk of Bangalore. In all, 5826 persons were referred
for sputum examinations.
Results of all the eight culture examinations were
available for 2973 (51% of the eligibles). Of these 64 persons were
positive by culture of atleast one specimen. Each of the eight specimens
has the chance of detecting a case and any one of them could be
considered as first or second specimen etc. To overcome this difficulty
80 permutations were randomly chosen out of the total 40,320 permutations
possible. Cases from first specimen and additional cases from subsequent
specimens were calculated through four mathematical equations. The
first equation namely Y = KXm (28.66 x-1.40) has been considered
as providing the best fit to the observed data. On the basis of
this equation it appears that additional positives could be obtained
upto the 1Oth specimen. Out of 64 culture positive cases, only 72%
of positives could be detected by first two samples. To get about
95% of the cases, it is necessary to examine at least six specimens
from each individual. Multiple samples are rewarding for detecting
even high grade cultures.
|KEY WORDS: MULTIPLE SPUTUM SPECIMEN, SPUTUM
EXAMINATION, CASE YIELD, PREVALENCE, CASE, SURVEY.
|PRECISION OF ESTIMATES OF PREVALENCE OF BACTERIOLOGICALLY
CONFIRMED PULMONARY TUBERCULOSIS IN GENERAL POPULATION
|SS Nair, GD Gothi, N Naganathan, K Padmanabha Rao,
GC Banerjee & R Rajalakshmi: Indian J TB 1976, 23, 152-59.
This paper reports on a study conducted in the
year 1975 to estimate yield of tuberculosis cases from multiple
sputum specimens, and work out correction factors to be applied
to estimates based on small number of specimens. Eight sputum specimens
were collected within a fortnight from each person with an abnormal
chest X-ray during an epidemiological survey in 77 villages in a
district of south India. Each specimen was examined by Ziehl-Neelsen
technique of microscopy and culture. In all, 3,199 persons were
referred for sputum examination and results of all the eight specimens
were available for 1,652. Of the latter, 64 were culture positive.
The first specimen detected 58% of the culture
positives and the additional positives by later specimens generally
decreased. The contribution from the first specimen was 71% for
cultures showing good growth and 19% for cultures with scanty growth.
Similarly for positives on both culture and microscopy, first specimen
detected 87% whereas the corresponding proportion was 32% for those
positive only on culture. The type of specimen (viz., spot or overnight)
and age or sex of the case did not influence the yield from multiple
examinations. The precision of an estimate of prevalence will depend
on the number of specimens on which it is based and the coverage
obtained in the collection and examination of specimens. Correction
factors to be applied to such estimates based on one or two specimens,
for various levels of coverage have been presented. For example,
an estimate of prevalence based on one sputum specimen with 90%
coverage will have to be nearly doubled to get a more precise estimate.
Using these correction factors, revised estimates of prevalence
have been presented for a number of prevalence surveys conducted
in India. It has been estimated that the total number of infectious
cases in India at present may be at least 3 million, as against
2 million according to earlier estimates.
|KEY WORDS: PREVALENCE, CASE, RURAL POPULATION,
MULTIPLE SPUTUM SPECIMEN, ESTIMATES, SPUTUM EXAMINATION.
|INCIDENCE OF TUBERCULOSIS AMONG NEWLY INFECTED POPULATION
AND IN RELATION TO THE DURATION OF INFECTED STATUS
|VV Krishnamurthy, SS Nair, GD Gothi & AK Chakraborty:
Indian J TB 1976, 23, 3-7.
Some of the parameters relating to duration of
infected status and incidence of disease have been measured by analysing
the data collected from the five year study. Between 1961-68, 119
villages in Bangalore district with total average population of
about 62,000 were surveyed at intervals of 1, 3 and 5 years from
the first survey. All persons were tuberculin tested with 1 TU RT
23 and those aged 5 years or more were X-rayed. Sputum of those
persons showing any X-ray abnormality were collected and examined
for AFB. Persons with X-ray abnormality but bacteriologically negative
or with normal X-ray in all the preceding surveys, and who became
culture positive with X-ray abnormality in the current survey were
termed as "New cases". New cases who had shown 10 mm or
more reaction to 1 TU RT 23 at I Survey were considered infected
previously. New cases, tuberculin negative at I survey but who showed
an increase of 16 mm or more between two consecutive surveys were
considered infected midway between the two surveys.
Of the 42 new cases diagnosed from among the newly
infected during 5 years, 81% came from those infected within one
year. Incidence rate of cases among those who were infected within
one year was about 5 times more than those infected earlier than
one year. Incidence of cases steadily decreased with the increase
in the duration of infection. Further, it was found that one fourth
of all newly diagnosed cases came from the newly infected persons.
However, the size of the pool of previously infected persons in
a community being much larger, at least 72% of the new cases came
from the reservoir of previously infected persons. The incidence
of disease among the newly infected was almost the same in the three
age groups i.e., 5-14, 15-34 and 35 years or more. But, the ratio
of the incidence rates for the newly infected and the previously
infected decreased from 13 for the age group 5-14 to 3 for the age
group 35 years and above. In other words, the incidence of disease
among the newly infected in the age group 5-14 was thirteen times
more than for the previously infected in the same age-group whereas
in the age-group 35 years and above, the incidence among newly infected
was only thrice that among the previously infected.
Out of the 160 new cases diagnosed during the three repeat surveys,
21 per cent cases came from among those who were infected on the
average for one year or less. This is almost in conformity with
the hypothesis that one-fourth of all new active cases come from
new infections less than a year old.
|KEY WORDS: INCIDENCE, INFECTION, CASE, TUBERCULIN
|RELAPSE AMONG NATURALLY CURED CASES OF PULMONARY
|AK Chakraborty & GD Gothi: Indian J TB 1976,
The five year longitudinal epidemiological study
in south India (1961-68) showed that a considerable proportion of
bacteriologically proven cases found in a survey got cured naturally
without the facility of organised treatment in the survey area.
This "natural cure" could be an epidemiologically significant
phenomenon- depending on the stability of such a cure or in other
words, the frequency of relapses among the naturally cured. In all,
108 naturally cured cases of tuberculosis out of a total of 269
cases, from among about 62,000 persons surveyed twice, were followed
up for varying periods of 1 to 3½ years.
It was observed that the average relapse rate was
85.4 per 1000 person years of observation, there being no difference
between the two sexes. Relapse rates were however higher in persons
aged 20 and more compared to those 5-10 years old. Relapses were
not dependent on the bacteriological status at initial diagnosis
i.e., whether positive by culture alone or positive by smear and
culture. The death rate among the naturally cured was 42.7 per 1000
person years and together with relapse constituted the unfavourable
fate after natural cure. It has been calculated that as an input,
adding to the pool of bacillary cases in the community, the ratio
of relapse cases to cases arising afresh from the general population
in a year would roughly be in the order of 1:16. It is concluded
that the naturally cured status could be considered as an epidemiologically
favourable situation, though much less so when compared to the chemotherapeutically
|KEY WORDS: RELAPSE, NATURAL CURE, CASE, RURAL
|ESTIMATION OF PREVALENCE OF BACILLARY TUBERCULOSIS
ON THE BASIS OF CHEST X-RAY AND/OR SYMPTOMATIC SCREENING
|GD Gothi, Radha Narayan, SS Nair, AK Chakraborty &
N Srikantaramu: Indian J Med Res 1976, 64, 1150-59.
The study was undertaken among 22,957 persons belonging
to 55 randomly selected villages of Nelamangala taluk of Bangalore
district in 1975, to find out precise estimates of prevalence of
bacillary disease. Symptom screening was done by well experienced
social investigators, according to a brief interview schedule. Sputum
was collected from all above the age of 5 years reporting chest
symptoms for seven or more number of days during the previous two
months. Within two weeks after symptom questioning, all were tuberculin
tested and all 5 years and above were X-rayed. Additional sputum
collection was done for those asymptomatics who had abnormal shadows
in their chest X-rays.
The overall prevalence rate of culture confirmed
bacillary cases by symptom and/or X-ray screening was 0.32 percent.
Same prevalence was seen with X-ray alone also. But the overall
prevalence rate based on symptom screening alone was 0.21 percent
which is significantly lower than that of symptom and/or X-ray screening,
or X-ray screening alone. The prevalence rates by age and sex based
on symptom screening were about two-thirds that of rate based on
X-ray and/or symptom screening. Hence to obtain prevalence rate
according to X-ray and/or symptom screening, a correction factor
of 1.52 should be applied to the prevalence rates obtained by symptom
screening alone. This correction factor is fairly good for most
of the age groups. It was also estimated that the cost of surveying
the population by symptom screening alone is about half that of
surveying the population by X-ray screening.
|KEY WORDS: PREVALENCE, CASE, SYMPTOM SCREENING,
X-RAY EXAMINATION, RURAL COMMUNITY.
|A COMPARISON OF NEW CASES (INCIDENCE CASES) WHO
HAD COME FROM DIFFERENT EPIDEMIOLOGICAL GROUPS IN THE POPULATION
|VV Krishnamurthy, SS Nair & GD Gothi: Indian
J TB 1978, 25, 144-46.
In a five year epidemiological survey conducted
by National Tuberculosis Institute (NTI) from 1961 to 1968, the
population was mainly classified into three epidemiological groups
(i) with no radiological abnormalities seen in the lungs (Group
N) (ii) having X-ray shadows of non-tuberculous etiology or tuberculosis
etiology but judged as inactive (Group M) and (iii) with shadows
of tuberculosis etiology judged possibly or definitely active but
negative on culture (Group S). The objective of this paper is to
compare the characteristics of cases coming from the above three
groups (N, M and S) in respect to bacillary disease status (a) at
the time of diagnosis and (b) after a lapse of time (Fate). Out
of the total 172 new cases diagnosed during three follow ups, 70
were diagnosed between I & II surveys, 40 between II and III
and 62 between III-IV surveys. In the two 18 months follow up periods,
45 of the total new cases had come from Group N, 31 cases from Group
M and 34 cases from Group S, corresponding figures for 24 months
follow up (III & IV surveys) were 26, 26 and 10 respectively.
In the 18 months follow up it was observed that
proportion of new cases positive on culture in the three groups
were not significantly different. Comparison of fate of cases coming
from three groups were similar in terms of cure, death and culture
positivity. The findings point out clearly that not only development
of disease but also the fate of cases is independent of pre diagnosis
status of the new cases.
From all the 3 groups, disease developed more rapidly
in some cases than in others. This reveals that tuberculosis cases
are not an uniform entity from the point of view of development
of the disease and cure.
|KEY WORDS: INCIDENCE, CASE, EPIDEMIOLOGICAL
GROUPS, RURAL POPULATION.
|INCIDENCE OF PULMONARY TUBERCULOSIS AND CHANGE IN
BACTERIOLOGICAL STATUS OF CASES AT SHORTER INTERVALS
|GD Gothi, AK Chakraborty, K Parthasarathy & VV
Krishnamurthy: Indian J Med Res 1978, 68, 564-74.
The incidence rates of sputum positive pulmonary
tuberculosis (cases) from the five year follow ups of a rural population
done by National Tuberculosis Institute were reported on the basis
of studies at intervals of one and a half to two years. Information
on fate of cases was also likewise reported. These parameters appear
to be imprecise since incidence and fate of cases at shorter intervals
were not taken into account. Thus, the information on incidence
of pulmonary tuberculosis in India is meager as compared to that
on prevalence of disease. Therefore, a study mainly to find out
the incidence and fate of cases at shorter intervals of 3-6 months
was undertaken in 87 randomly selected villages of Nelamangala sub-division,
Bangalore district which was one of the 3 sub-divisions where repeated
epidemiological surveys had been conducted between 1961-68. The
sample of villages in the present investigation was other than that
included in the earlier report. Organized Case-finding, anti-tuberculosis
treatment and BCG vaccination neither existed nor could be provided
in the area till the completion of the study. The present study
was conducted between 1968-1972.
This study conducted among 30,576 persons has shown
that incidence of cases over a period of three months was 0.99 per
thousand and was not much different from the annual rate of 1.03
per thousand reported on the basis of repeated surveys at longer
intervals. That the three months rates were not a quarter of the
annual rates meant that the procedure of calculating incidence rates
on the basis of surveys done at varying intervals after adjusting
for the interval had to be used with great caution. The study of
fate of cases showed that cases converted or reverted even at shorter
intervals and this appeared to be going on continually in the community.
However, incidence of cases and cure and death from among the existing
as well as the fresh cases kept on balancing each other so that
the prevalence rates of cases studied at shorter or at longer intervals
did not show variations.
|KEY WORDS: INCIDENCE, FATE, CASE, RURAL POPULATION,
SURVEY, SHORTER INTERVALS
|CHEST DISEASES AND TUBERCULOSIS IN A SLUM COMMUNITY
AND PROBLEMS IN ESTIMATING THEIR PREVALENCE
|AK Chakraborty, GD Gothi, Benjamin Issac, KR Rangaswamy,
MS Krishnamurthy & R Rajalakshmi: Indian J Public Health 1979,
The entire population of a slum area of Bangalore
city, comprising of 3313 persons was registered, questioned for
symptoms and offered chest X-ray at a centre located in the slum
itself. Those, who had any chest symptom and/or X-ray abnormality,
were offered detailed examinations, viz., clinical examinations,
repeated examinations of sputum for tubercle bacilli, and further
chest X-rays. Of the total 2855 persons X-rayed and/or questioned,
1039 needed detailed examinations and about a fifth of the latter
required referral to a consultant panel for diagnosis of chest diseases.
Further, about 60% of those referred to consultants needed special
investigations. Thus, the study of prevalence of chest diseases
in the community needed considerable facilities and were operationally
difficult. It is envisaged that similar problems will also be faced
if peripheral dispensaries are to make proper diagnosis of chest
diseases, due to the need for referral of large number of patients
and provision of complicated diagnostic facilities at the referral
hospitals. The study seeks to quantify the problem of chest diseases
and tuberculosis in the slum community.
The prevalence of sickness in the population at
any point of time were 49.5%. Sickness related to the respiratory
system was 13.3%. It increased with age and was highest (42.6%)
in those aged 55 years and above. Among 2855 persons X-rayed, 145(5.1%)
had any radiological abnormality in chest. It is seen that respiratory
systems symptoms were commonest in all the age groups. A total of
172 patients were diagnosed to have respiratory system abnormalities
with or without X-ray lesions. Of them, 75% had non- tuberculous
etiology, 7.6% had active pulmonary tuberculosis and the remaining
17.4% had inactive tuberculosis. Prevalence of sputum positive cases
was 0.26% and prevalence of total active pulmonary tuberculosis
was 0.44%. The problem of arriving at final diagnosis was dependent
on application of complicated special investigation tools to a large
community. In view of the low coverage (47.4%) for the special investigations,
prevalence of different chest diseases in the community could not
It is concluded that in the community under study,
the size of the problem of non- tuberculous diseases of the chest
and operational problems in their diagnosis were considerable.
|KEY WORDS: PREVALENCE, URBAN, SLUM COMMUNITY,
CHEST DISEASES, CASE.
|INCIDENCE OF TUBERCULOSIS CASES IN CONTACTS - A
|AK Chakraborty, Hardan Singh & P Jagota: Indian
J Prev & Soc Med 1980, 11, 108-11.
Contact examination is not recommended as a routine
procedure for Case-finding in the District Tuberculosis Programme.
The rationale for not including contact examination as a routine
Case-finding measure is: (1) prevalence rate of tuberculosis among
the contacts is not much higher than in the general population (2)
at the time of diagnosis of an index case, a second case may not
be found in the same household. Though more prevalence cases cannot
be diagnosed by contact examination, is it possible that by keeping
the household contacts, as a group, under surveillance, future incidence
of cases in the community can be substantially prevented? A model
situation has been created by using hypothesis derived from various
studies conducted in India, designed to answer the question. Variables
used in the model are: 40% of the general population are infected
at any point of time, there is only one prevalence case of TB at
any given point of time in an average household of five, 40% of
the non-infected population in a contact household are infected
per year, incidence of disease among newly infected group is seven,
times of the incidence among previously infected, incidence of disease
in general population is 0.13% and from among previously infected
persons 0.3% per year develop sputum disease.
At an incidence rate of 0.13% per year among general
population aged >5 years, it is expected that 111 cases would
arise in a year in the population of 1,00,000 under study. Thus,
of the 111 cases occurring in the community, 101 arise from those
who are not contacts.
The proportional contribution of new cases from
the contact group to the total incidence cases in the entire community
is so small, that even if all the contacts are kept under surveillance,
BCG vaccinated or placed on chemoprophylaxis, still over 90% of
incidence cases cannot be prevented from occurring. This is apart
from the fact that keeping them under surveillance will be highly
costly and is an operational problem of considerable magnitude.
|KEY WORDS: INCIDENCE, CASE, CONTACTS, MODEL
|MORTALITY AND CASE FATALITY OF TUBERCULOSIS CASES
DIAGNOSED IN A RURAL POPULATION OF SOUTH INDIA
|VV Krishna Murthy: NTI Newsletter 1982, 19, 8-13.
Mortality from tuberculosis is an important epidemiological
parameter for defining the problem of tuberculosis in any country.
But due to lack of systematic recording and reporting system, precise
information on cause of death is not available in our country. An
attempt has been made to estimate the case fatality of tuberculosis
cases as well as mortality of cases diagnosed in a longitudinal
study conducted from 1961-68 in Bangalore district. Crude mortality
of cases is defined as the ratio of total deaths observed among
cases to the total number of cases observed, while case fatality
is defined as the ratio of deaths that have occurred due to tuberculosis
to the total number of cases investigated.
The overall observed annual crude mortality was
14.8%, while among culture positive smear positive (C+S+) it was
21%. An upward trend was seen with the increase in the age. The
overall annual crude mortality among culture positive smear negative
(C+S-) cases was 9.5% which is significantly lower than that among
C+S+ cases. The death rates among old and new cases at the end of
18 months were 16.7% and 13.7% respectively. No statistical difference
was found in the crude mortality either among old and new cases
or in relation to the interval of diagnosis. Case fatality due to
tuberculosis was computed by calculating the deaths among non-tuberculosis
population of the same area and during same period and eliminated
from the total deaths observed among tuberculosis cases. The case
fatality of tuberculosis was found to be 13.3%. It was further observed
that out of the total 38 deaths among cases, 89% were due to tuberculosis
and 11% were due to non-tuberculosis causes.
|KEY WORDS: MORTALITY, CASE FATALITY, CASE, RURAL
|TUBERCULOSIS IN A RURAL POPULATION OF SOUTH INDIA:
REPORT ON FIVE SURVEYS
|AK Chakraborty, Hardan Singh, K Srikantan, KR Rangaswamy,
MS Krishnamurthy & JA Steaphen: Indian J TB 1982, 29, 153-67.
The trend of tuberculosis in a sample of 22 villages
of Bangalore district observed over a period of about 16 years (1961-77)
is reported. Distribution of tuberculin indurations did not show
a clear cut demarcation between infected and non-infected. The method
adopted to demarcate the cut off point has been described herewith:
Distribution of tuberculin induration size of 0-14 years was attempted
and extrapolated to higher age groups. Even in these younger age
groups the antimodes were not clearly defined, so the antimode was
arrived by fitting two normal curves as two likely modes.
The choice of demarcation level, therefore, is
somewhat arbitrarily made on the basis of the distributions and
these varied from survey to survey; between 10 mm at survey I and
16 mm at survey V. The actual and standardized infection rates showed
more or less declining trend in 0-4 years, 5-9 years and 10-14 years
age groups. The prevalence of cases was not significantly different
from survey to survey (varying from 3.96 to 4.92 per thousand from
first to fifth survey). However, there was a shift in the mean age
of cases, and better survival rate of cases diagnosed at later surveys.
|KEY WORDS: TREND, CASE, INFECTION, PREVALENCE,
TUBERCULIN READING METHOD, LONGITUDINAL SURVEY.
| DISTRIBUTION OF TUBERCULOSIS CASES AMONG FAMIILY
RELATIONS IN A RURAL COMMUNITY
|R Channabasavaiah & AK Chakraborty: NTI Newsletter
1984, 20, 63-72.
Material from a community survey carried out in
rural areas of Karnataka by the National Tuberculosis Institute,
Bangalore, has been analysed in an attempt to identify significant
categories of the population that may yield higher proportion of
cases. In all, 170 cases diagnosed among 61,581 persons have been
distributed by their role, i.e., head of family (HOF) or not, kinship,
(relationship to the HOF) by age and sex.
It has been observed that a comparatively small
size of HOF male population (16.9%) would contain 55.9% of the total
cases prevalent in the entire X-rayed population. On the other hand,
the broad category other than HOF-male, would have case content
relatively much less in proportion to their population size. Implications
of the finding for house-to-house Case-finding by Multi-purpose
Health Workers (HWs) are discussed here. It is possible to obtain
higher case yield from the group having a higher case content which
is aged 20 years and above and constitutes about 30% of the total
population by confining to symptom screening. On the other hand,
since cases are mostly in the HOF-males, would make it difficult
for HWs to contact them in their normal visiting hours during day,
as most of HOF-males may not be at home. Determined efforts have
to be made by HWs to contact them during their beat schedule.
|KEY WORDS: CASE, FAMILY, RURAL COMMUNITY.
| PREVALENCE OF PULMONARY TUBERCULOSIS IN A PERI-URBAN
COMMUNITY OF BANGALORE UNDER VARIOUS METHODS OF POPULATION SCREENING
|AK Chakraborty, R Channabasavaiah, MS Krishna Murthy,
AN Shashidhara, VV Krishna Murthy & K Chaudhuri: Indian J TB
1994, 41, 17-27.
Screening of the population by Mass Miniature Radiography
(MMR) followed by sputum examination by culture of the X-ray abnormals
is the customary method for arriving at the prevalence rate of cases
in the community. It is not possible to use this methodology by
states to carry out prevalence surveys in these areas, even if they
desire to evaluate the effect of anti tuberculosis measures implemented
by them. Therefore, simpler means of screening population through
chest symptom for sputum examination has been studied by National
Tuberculosis Institute (NTI). The objectives of the present investigation
were to find out the prevalence of bacillary cases by screening
the population through identification of chest symptomatics by Social
Investigators (Sls) or General Health Workers (GHWs) compared to
that by MMR. In a peri urban area 10 kms away and around Bangalore
city all the villages were listed and of the 60 villages were selected
on the basis of a sample random sample. Of them, 30 were covered
by Sls of NTI and the other 30 by GHWs of the state government.
The methodology adopted was that (1) After census taking and registration
of the entire population aged 15 years and above, Sls questioned
the persons house to house for presence of cardinal chest symptoms
of any duration. All chest symptomatics were subjected to MMR and
sputum examination. (2) Similar methodology was adopted by GHWs
in the other 30 villages allotted to them. (3) Without knowing the
symptom status of all the registered persons, aged 15 years and
more belonging to all the 60 villages, were subjected to MMR and
from among those having X-ray abnormalities, to sputum examination.
It was found that GHWs had identified the same
proportion of the persons either having general symptoms or having
chest symptoms from the general population, as Sls. Prevalence rates
of culture positive as well as smear positive cases were similar
by any of the three methods i.e., 0.18%, 0.23% & 0.25% respectively.
Prevalence rates of smear positive cases obtained through symptom
questioning, either by Sls or GHWs, were more or less similar to
the estimates obtained by the more comprehensive screening method
of MMR and/or symptom questioning. The culture positive prevalence
rate following MMR screening was 0.25%, which was lower than the
rates observed in other surveys. The paper discusses the possible
hypothesis that could explain the observation. It also presents
correction factors to compute rates comparable to the best estimate
i.e., that obtained through comprehensive screening by MMR and/or
symptom questioning, followed by sputum culture.
|KEY WORDS: SCREENING TOOLS, CHEST SYMPTOMATICS,
MMR, PREVALENCE, CASE, PERI URBAN COMMUNITY.