Introduction:
Tuberculosis (TB) is one of the most important causes of global premature mortality and
disability - projected to remain as one of the ten leading causes of disease burden by the year 2020.1 The risk
of transmission from the index case to its contacts is more; particularly in case of smear positive Pulmonary Tuberculosis
cases.2 Any delay in diagnosis and treatment increases the risk of disease transmission to their contacts. Contact
screening is important for early detection of transmission of infection.3 Contact investigation is rarely done in
developing countries because of other priorities and lack of resources.4 This has been an Internationally
recommended strategy in prevention of Tuberculosis.5 The standards of TB care in India also recommends’ the
contact investigation of Index cases.6 Active Case Finding (ACF) and house-to-house survey have shown to be
effective in the detection of new cases even in the developed countries.7 Studies have shown that active case
finding among household contacts yields more TB cases.8-10 Thus, active case finding of TB is needed, particularly
to identify the case yield among household contacts. Hence, the objective of the study was to identify the TB
suspect and estimate the prevalence of TB among household contacts in this region.
Methods:
Study design and Study setting:
A community-based two-stage cross-sectional study was conducted in the localities of
Puducherry district which comes under the State Tuberculosis Unit (TU) of Puducherry Union Territory, India. The present
study was undertaken by the Department of Community Medicine, Sri Manakula Vinayagar Medical College and Hospital,
Pondicherry, which is an active member in STF-RNTCP (State Task Force- Revised National Tuberculosis Control Program)
mechanism and periodically organizes training program on Revised National Tuberculosis Control Program (RNTCP) guidelines
for various health professionals such as doctors, nurses and medical interns.11
Study Population and study period:The household contacts of all cases of ‘New Smear
Positive’ (NSP) Pulmonary Tuberculosis registered between October 2011 and September 2012 in the TU of Puducherry, were
invited to participate in the study.
Data collection: All the household contacts were screened using a contact investigation
check list by the first author. The first author made home visits to the registered NSP patients, traced, identified and
screened the household contacts for symptoms for tuberculosis within two months of registration of the index case. A follow
up visit was made after 8 months of registration of index case, to assess the further development of symptoms of TB among
the household contacts. The TB suspects were identified and two sputum samples (one spot and early morning sample) were
collected from all the symptomatic contacts in a sputum container with patient’s name written on its side. The specimens
were stained by using Ziehl-Neelsen technique and examined by a trained laboratory technician at the nearby Designated
Microscopy Centre.12 The children’s below five years were accompanied to the nearest health centre for further
evaluation and requirement for isoniazid prophylaxis or TB treatment was assessed. The sputum positive household contacts
were referred and started on treatment from the nearby DOTS centre under the supervision of TB health visitor.
Ethical issues: Ethical principles such as obtaining informed consent, respect for
the persons, beneficence and justice were adhered. Clearance was obtained from the Research Committee and
Institutional Ethics Committee of Sri Manakula Vinayagar Medical College and Hospital, Madagadipet, Puducherry. All those
who were found to have tuberculosis were referred to nearby government health care facility, which is equipped to treat
tuberculosis.
Data analysis: Data was entered using Epi Info (Version 3.4.3) software package and
analysed. Statistically, ‘Proportions’ was used to find out the prevalence of Pulmonary Tuberculosis among the household
contacts, different age groups, gender and others like socio- demographic details, environmental factors. Odds ratios were
calculated with 95% Confidence Intervals (CI) and the Chi-square (c2) test were used to assess the association
between the symptomatic contacts and their personal details, environmental factors and with their respective index case
details to test the level of significance.
Results:
Out of 299 registered cases in the given reference period, we could contact 157 index cases
and their 472 contacts. We have excluded 142 index cases, 55(18.4%) due to wrong address, 23 (7.7%) index cases refused to
give consent, 35 (11.7 %) were not available even after three consecutive home visits, 15 (5.016%) were transferred to other
states, 5(1.6%) index cases were dead within one month of diagnosis and 9 (3.01%) were living alone.
A total of 472 Household contacts were identified and recruited in the study (Figure No: 1).
The majority of household contacts 269 (57%) were between the age groups 15 – 45 years and 125 (26.5%) belonged to 0-14 years
of age group, 59(12.5%) belonged to age group 46-60 years and remaining 19 (4%) were above 60 years. Among the household
contacts 277 (58.7%) were female and 195(41.3%) were male (Table 1).
| Table 1: Characteristics for the study subjects and their personal details |
Variables |
With Symptoms
n =96 |
Without Symptoms
n =376 |
Total
n=472 |
Age group (in years) |
|
0-14 |
1 (1.0) |
124 (33.0) |
125 (26.5) |
15-30 |
30 (31.3) |
130 (34.5) |
160 (33.9) |
31-45 |
39 (40.6) |
70 (18.6) |
109 (23.1) |
46-60 |
18 (18.8) |
41 (10.9) |
59 (12.5) |
>60 |
8 (8.3) |
11 (2.9) |
19 (4.0) |
Gender |
|
Male |
21 (21.9) |
174 (46.27) |
195 (41.3) |
Female |
75 (78.1) |
202 (53.7) |
277 (58.7) |
Education level* |
|
Illiterate/Primary |
47 (49.0) |
137 (36.4) |
184 (38.9) |
Middle |
17 (17.7) |
86(22.8) |
103 (21.8) |
Secondary |
16 (16.6) |
64(17.02) |
80 (16.9) |
Higher secondary |
10 (10.4) |
24(6.38) |
34 (7.2) |
Degree |
6 (6.25) |
35(9.3) |
41 (8.7) |
Test of significance (c2, df, p-value) 5.76, 4, 0.218 |
|
Occupation** |
|
Daily wages |
32 (33.3) |
110 (29.3) |
142(30.0) |
Housewives |
43 (44.8) |
54 (14.4) |
97(20.5) |
Business |
2 (2.1) |
11 (2.9) |
13(2.7) |
Salaried |
1 (1.0) |
15 (4.0) |
16(3.3) |
Un employment |
7 (7.3) |
24 (6.4) |
31(6.5) |
Test of significance (c2, df, p-value) 19.95, 4, 0.0005 |
|
Smoking habit |
|
Present |
12 (12.5) |
75 (19.9) |
87(18.4) |
Absent |
6 (6.3) |
26 (6.9) |
32(6.7) |
Test of significance (c2, OR, 95%CI) 0.51, 0.693, 0.2362-2.035 |
|
Alcoholism |
|
Present |
14 (14.6) |
88 (23.4) |
102(21.6) |
Absent |
4 (4.2) |
13 (3.5) |
17(3.6) |
Test of significance (c2, OR, 95%CI) 0.32, 0.517, 0.1475-1.813 |
|
| Figures in parenthesis are percentages, *Children below 4 years excluded in education, **Students were excluded in occupation, *** Females and children in were addiction history |
Among the household contacts, 70 (14.8%) were found to have symptoms of TB during visit made
within two months of registration of index cases and 26 (5.5%) household contacts had symptoms of TB during follow visit made
after eight months after registration of index cases. The symptoms of TB were common in the age group of 31 – 45 years,
39 (40.6%) and females 75 (78.1%). The symptoms of TB were more common among the their spouses 47(49%) and children 17 (17.7%).
It was also found that majority of the symptomatic household contacts 66 (68.8%) belong to Urban area. In the symptomatic
household contacts 3(4.3 %) were found confirmed to have Tuberculosis.
It was also found that environmental risk factors like overcrowding was present in 65(67.7%)
and cross ventilation was absent in 71 (74%) in the houses of the household contacts.
Discussion
The total of 299 (73.3%) index cases were registered in State Tuberculosis Unit, Puducherry
during the study period from October 2011 to September 2012.We could trace 157 (52.5%) cases and their 472 contacts.
The symptomatic household contacts during visit made within two months and after eight months were 70 (14.8%) and 26 (5.5%)
respectively. Out of 70 symptomatic, 3(4.3%) were confirmed to have tuberculosis.
We have excluded 142 index cases of which 55(18.4%) were excluded due to wrong address,
23 (7.7%) refused to give consent, 35 (11.7 %) were not available even after three consecutive home visits, 15 (5.01%) were
transferred to other states, 5(1.6%) were dead within one month of diagnosis and 9 (3.01%) were living alone. This findings
are similar to the studies conducted in India.5,9 In a study conducted inVietnam the reasons for not
to participate were, the death of the index case, absence at the time of interview, or having moved to another address.
10 In our study the majority of index cases were excluded due to wrong address. This can be reduced by ensuring
the completeness of the TB treatment card at PHI (Peripherial Health Institution) with respect to address of the contact
person and initial home visit by the TB health visitor.13
A prevalence of tuberculosis infection was 4.3 % among household contacts during the study
period. It was found that the prevalence rates of tuberculosis among household contacts was varying between 1.2% to 8.3% from
the studies reported from different parts of the world including India.2,3,7,9,10,14-16 This leads to the
assumption that many of these current cases were in fact infected by a member of their own family.17
Golub JE et al have shown that close contact with tuberculosis patients was associated
with smear positivity among household contacts.18 In our study we also found thet the symptoms of TB were more
common among the close contacts of the index case, their spouse, 47(49%) and children, 17 (17.7%).
In our study, out of 472 household contacts screened using the questionnaire, 20.3% were
found to symptomatic. In the screened household contacts, 4.3% were found to be smear-positive. We have found that active
case finding among household contacts of TB patients can serve as an additional method for identifying new TB cases in the
community. Hence, combined active case finding among household contacts and passive case finding can detect substantially
more cases of TB, which is also evident from other studies.5,19 As per the RNTCP guidelines11 in
India, it is prerequisite to screen the household contacts of children below 6 years, but by extending the same to all
the household contacts as indicated in Standards of TB care in India6 will help to reduce the burden of
Tuberculosis in the community.
The limitation of our study is that, it was restricted only to newly diagnosed smear positive
pulmonary tuberculosis, and their household contacts. However if the smear negative patients and extra pulmonary tuberculosis
were included it would have been complete coverage. This could not be undertaken in the present study due to shortage of time
and the paucity of resources.
Conclusion:
Considering the prevalence tuberculosis among the symptomatic of household contact to be 4.3%,
their investigation to rule out TB in earlier stages is a need. It may help prevent further spread of M. tuberculosis
infection in community.
Conflicts of Interest:
The authors declare that they have no competing interests.
Acknowledgement:
The authors acknowledge the funding received from Chest clinic,
Pondicherry under RNTCP financial assistance - MD-PG thesis grant.
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