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Indian Journal of Community Medicine

An Epidemiological Study of Prevalence of Tuburculosis in the Urban Slum Area of Ahmedabad City

Author(s): A.M. Kadri, A. Bhagyalaxmi, M.K. Lala, Parimal Jivrajini, Madhu Vidhani, Tushar Patel

Vol. 28, No. 3 (2003-07 - 2003-09)

Deptt. of Community Medicine, B.J. Medical College, Ahmedabad

Abstract:

Research questions: (l) What is the prevalence of Tuberculosis in slums of Ahmedabad? (2) What is the relation of age, sex and occupation with the prevalence of Tuberculosis? (3) What is the relapse rate?

Objective: To study prevalence of tuberculosis in urban slums of Ahmedabad city and to find out relevant epidemiological factors playing important role.

Study design: Cross-sectional.

Setting: 30 clusters from slums of Ahmedabad City.

Participants: 10864 people of the slums and 51 cases of Tuberculosis from this population were taken for detailed study.

Study variables: Caste, age, sex, occupation etc.

Statistical analysis: Chi-square test, proportions.

Results: Overall point prevalence of tuberculosis was found to be 4.69/1,000. Higher prevalence was observed among males (5.44/1,000) in comparison to females (3.81/1,000). Rise in the prevalence with increase in age was seen with highest prevalence in the age group of 60+ (4.81/1,000). Retired persons reported high prevalence (25.21/1,000). Unemployed and service people were having prevalence of 4.41/1,000 and 4.14/1,000 respectively. 59.4% of the studied cases had suffered from tuberculosis more than once.

Key Words: Prevalence, Age, Sex, Occupation, Tube

Introduction:

India has more cases of TB than any other country. In India. the estimated prevalence of sputum positive patients is 0.4% (3.5 million cases)1. Current tuberculosis epidemic in India started probably in the mid 19th century, reached at its peak some 50 years later at the beginning of 20th century and that it has been naturally declining slowly over years. But we were having little information about the country picture on tuberculosis2.

According to the review of global tuberculosis by WHO, India comes under a group of high prevalence countries with annual risk of infection ranging between 1-2.5%3. It is generally agreed that currently in India there are about 14 million suspected and about 3.5 million bacteriologically proved cases of pulmonary tuberculosis with prevalence of 4.84/1,0004.

The first attempt to have an estimation of prevalence of tuberculosis was carried out nationwide by Indian Council of Medical Research in a sample survey study during 1955-58. Thereafter, from time to time prevalence studies were conducted by different people and institutes.

Baseline information on the disease situation is one of the prerequisites for the development of appropriate control measures.

It is equally important to have adequate information on epidemiological, social, economic and cultural factors and their interaction, which not only influence the spread of tuberculosis but also ought to influence the methods of control and effective treatments.

Material and Methods:

Based on a pilot study carried out in one of the slums of Ahmedabad, prevalence of tuberculosis was estimated to be 9/1,000 in general population of the slums. A sample size of 10,565 was calculated at 5% level of significance and 20% allowable error.

30 cluster sampling method was adopted for study. These clusters were identified from 43 election wards of the city. From each cluster nearly 353 persons (around 71 houses) were studied. Besides socio-demographic information of the population, any case of tuberculosis present in the family in the last twelve months from the date of survey was taken up for detailed study. For the study purpose, a case of tuberculosis meant a person who was diagnosed by practicing doctor and put on the treatment tuberculosis (case paper, file, prescription or investigation for and drug history was sought for further confirmation).

Results:

Table I: Prevalence Rate (PR) of Tuberculosis according to age and sex,

Age V (Years) Male Female Total
Population studied Cases P.R./1,000 Population studied Cases P.R./1,000 Population studied Cases P.R./1,000
0-9 1283 2 1.56 1084 2 1.84 2367 4 1.69
10-19 1521 1 0.66 1225 0 0.00 2746 1 0.36
20-29 999 7 7.01 925 3 3.24 1924 10 5.20
30-39 832 8 9.62 823 8 9.72 1655 16 9.67
40-49 673 4 5.94 540 3 5.56 1213 7 5.77
50-59 350 6 17.14 204 1 4.90 554 7 12.64
60+ 218 4 18.35 187 2 10.69 405 6 14.81
Total 5876 32 5.44 4988 19 3.81 10864 51 4.69

2,148 houses were surveyed and total 10,864 persons were studied. Out of them 5,876(54.09%) were males and 4,988(45.91%) were females. Sex ratio was 848.87. The mean age of males and females were 24.6±1.69 and 24.24±1.63 years respectively. 47.06% of the population belonged to 0-19 age group, 49.21% belonged to 20-59 age group while 3.73% were sixty or above sixty years of age (Table I).

Point prevalence of tuberculosis cases found in the surveyed population was 4.69/1,000 (of all ages and both sexes). Males were having higher prevalence (5.44/1,000) in comparison to females (3.81/1,000). This difference was statistically not significant. (Z=0.27, p>0.05). The lowest prevalence was seen in the population of below 20 years of age group, thereafter, it showed increasing trend with rising age except 40-49 years of age. People of sixty years and above had highest prevalence i.e. 14.81/1,000 (Table I).

The prevalence of tuberculosis among Hindus and Muslims was 4.6/1,000 and 3.8/1,000 respectively. Overall prevalence of tuberculosis in adult population was 8.03/1,000. The highest prevalence was found in retired persons (25.21/1,000). Labourers were second in the list with prevalence of 10.95/1,000 followed by businessmen (8.22/1,000). Unemployed and service people were having 4.41/1,000 and 4.14/1,000 prevalence respectively.

Every second patient (54.9 %) had already suffered from tuberculosis previously. More than 90% of the cases were of pulmonary tuberculosis, 3.92% were cases of extra pulmonary tuberculosis and 3.92% were having both types of tuberculosis.

Discussion:

The studied population showed age pyramid having broad base and tapering top. In the study of epidemiology of tuberculosis in an urban population of New Delhi the age composition of the studied population showed pattern typical of a developing country6.

Prevalence of tuberculosis in the study area was 4.69/1,000 which is less than the national rate (5.44/1,000), but quite near to the State (4.38/1,000) rate and higher than the findings of urban Gujarat (2.79/1,000) in National Family

Health Survey-2 (NFHS-2)7. Present study was carried out in the slums of Ahmedabad, which may be the reason behind the difference.

Prevalence of tuberculosis was found to be higher (5.44/1,000) in males than females (3.81/1,000). However, the difference was not significant (Z=0.27, p>0.05). A study carried out in Raichur district of Karnataka also showed higher prevalence in males (11.9%) than females (7.l%)8. In another survey carried out in the urban population of Delhi prevalence was 4.3/1,000 and 2.24/1,000 respectively for males and females6. NFHS-2 also states higher prevalence of tuberculosis among males (6.24/1,000) than females (4.6/1,000)7.

With the increasing age, prevalence of tuberculosis rises. Highest prevalence was seen in persons aged 60 years and above, while lowest in childhood. This observation can be related with that of NFHS-2 (13.74/1,000 in 60+ years and 1.53/1,000 in 0-14 years) and survey carried out in urban population of Delhi (highest prevalence in the 55+ age group (11,98%)6,7. Increasing age weakens the resistance to the diseases is the proven fact behind the high prevalence in aged people, while low prevalence in children may be due to BCG vaccination as it is claimed to provide protection against childhood tuberculosis.

Religion played little role in the prevalence of tuberculosis as there was not much difference in the prevalence among Hindus and Muslims, whereas, among Christians and others prevalence was 30/1,000. Since, they were reported only in a very few so statistical conclusion was not considered in the present study.

Retired persons showed highest prevalence of tuberculosis, as they were the old age people with weak immunity. Higher prevalence in the labourers and businessmen can be related with the mobility, and possibilities of coming in contact with large number of people. Labourers are having higher mobility and businessmen are having higher chances of coming in contact to different people in contrast to unemployed who were showing lowest prevalence.

The alarming finding of the study was that more than half of the cases (54.9%) had already suffered from tuberculosis at least once.

Limitations:

The diagnostic criteria used in the study was "Diagnosed by any registered practitioners, Government or Private", which may not be always 'Bacteriologically diagnosed' cases of the tuberculosis. So, comparison with other studies are guarded in this paper.

References:

  1. Technical guidelines for tuberculosis control. Central TB Division, Directorate General of Health Services, Nirman Bhavan, New Delhi, 1999.
  2. Stefan Gryzoboski. Epidemiology of Tuberculosis with particular reference to India. Indian Journal of tuberculosis 1995; 42:195-200.
  3. Kothi A. The global tuberculosis situation and the new control strategy of the World Health Organization. Tubercle 1991; 72.
  4. Lalit Kant. On estimation of Burden of tuberculosis in India. Indian Journal of tuberculosis 2000; 47:1298-9.
  5. Nair SS. A comprehensive, multipurpose. National Sample Survey on Tuberculosis - A challenge and a golden opportunity. Indian Journal of Tuberculosis 2000; 47: 53-7.
  6. Study of epidemiology of Tuberculosis in an urban population of Delhi: Report on 30 years follow-up. Indian Journal of tuberculosis 1999; 46: 113-24.
  7. National Family Health Survey-2 India. International Institute for Population Sciences, 1998-99; Mumbai 198-202.
  8. Gopi PG, Vallishayee RS, Appe Gowda BN, Paramasivan CN, Ranganatha S, Venkataramu KY et al. A tuberculosis prevalence survey based on symptoms questioning and sputum examination. Indian Journal of Tuberculosis 1997, 44: 171-80.
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