The commencement of Epidemiology activities related to TB by TRC dates back to 1968 when the BCG trial in tuberculosis was started in Chingelput, district. Since then the BCG Trial area has been successfully utilized as the population laboratory for the study of the epidemiology of Tuberculosis. After the BCG Trial, disease prevalence surveys were undertaken by TRC, in Raichur, (Karnataka) and North Arcot (Tamilnadu) to estimate the case load in these districts to assist in the evaluation of implementation of the National Tuberculosis programme in these districts. An operational study to document the fate of smear positive cases after chemotherapy was carried out in North Arcot district. The RNTCP was introduced in the BCG trial area in 1999. Currently the Disease Survey and Tuberculin survey are being carried out in the BCG trial area to study the impact of DOTS strategy (RNTCP) on the epidemiology of TB. A case control study was done in 1998 to study the association between Tobacco smoking and Pulmonary TB. In the ongoing disease survey, the information on exposure to risk factors like Tobacco smoking, alcohol consumption are being collected to study the association between these behavioral risk factors with pulmonary TB. The epidemiology unit of TRC has also collaborated with National Tuberculosis Institute, Bangalore, in conducting a nation wide sample survey (tuberculin survey). Studies on mortality among cohorts of tuberculosis patients from Chennai Corporation and Thiruvallur district were completed. Mortality surveys were completed in Andhra Pradesh and Orissa.
Head of Department: Dr. C. Kolappan, Scientist F
Email: kola155@trcchennai.in
Ongoing Studies: 1) Epidemiological impact study: Survey of tuberculosis disease and infection
Principal Investigators: Dr. C. Kolappan, Mr. R. Subramani, Dr. P.G. Gopi
2) Mortality surveys in Andhra Pradesh and in Orissa
Principal Investigator: Dr. C. Kolappan
Funding: GFATM through Central TB division
Ongoing Studies:
1) Epidemiological impact study: Survey of tuberculosis disease and infection
Principal Investigators: Dr. C. Kolappan, Mr. R. Subramani, Dr. P.G. Gopi
Directly Observed Treatment under Short course (DOTS) is the standard of care for management of TB and globally accepted and recommended by World Health Organisation (WHO) in 1991. Information on impact of DOTS on disease prevalence is limited based on population-based surveillance. After the implementation of DOTS in Tiruvallur district in 1999, a series of epidemiological surveys were undertaken in the five blocks of Tiruvallur consisting a population of about 5.8 lakh with a view to estimating the trends of the disease over a period of time and to demonstrate the epidemiological impact of DOTS on TB. The first survey was conducted during 1999-2001 which documented baseline information on TB like prevalence of smear-positive cases, culture-positive cases among adults aged 15 years and above. The tuberculin survey provided data on prevalence of infection and ARTI among children aged less than 15 years. The two disease surveys completed at an interval of 2.5 years have shown a decline in TB prevalence for both smear-positive cases and culture-positive cases. An estimate of the incidence of TB was also obtained. The second and third tuberculin surveys were completed and the analysis was carried out on data from all the three surveys. An annual decline of 6% in prevalence of TB infection was observed from the first and the third surveys conducted at an interval of 4 to 5 years. The II Resurvey was started and completed in the same population using the same methodology. With this survey, a precise estimate on the decline of TB would be obtained. The III Resurvey was started in June 2006.
Apart from the above epidemiological surveys, operational research on different components of the programme is under way.
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2) Mortality surveys in Andhra Pradesh and in Orissa
Principal Investigator: Dr. C. Kolappan
Funding: GFATM through Central TB division
The aims of this study are to
(i) Estimate crude mortality rate in the states of Andhra Pradesh and Orissa.
(ii) Estimate the tuberculosis mortality rate among the general population aged > 15 years.
This is a retrospective cohort study of a sample of 380,000 population each from Andhra Pradesh and Orissa. The cause of death during the follow-up period was ascertained by interview (verbal autopsy). The cause of death was coded using ICD 10 codes.
Survey Period: September 2005 – April 2006.
Study relevance: This study is the first community based TB mortality survey and the findings will form the baseline data for monitoring the trend in the community. Study is completed and the report is being written.
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