Trends in initial drug resistance over three decades in rural community in South India.

Tuberculosis Research Centre (ICMR), Chennai

Indian Journal of Tuberculosis; 2003; 50; 75-86.

Background : The magnitude of initial drug resistance has important implications for the tuberculosis control programme.

Aims : To study trend of initial drug resistance over a period of three decades in a rural community in five panchayat unions in Chingleput district in south India.

Methods : A total population survey of tuberculosis in the area was undertaken in 1968-70, comprising radiographic examination of all individuals aged 10 years or more and sputum examination of those with abnormal shadows. Subsequently, the total population survey was repeated on 6 occasions at intervals of 2.5 years along with new entrants found at each survey, and on two more occasions (1991-92, 1994-96) in a subset of two panchayat unions. Prevalence cases and (new) incidence cases of culture-positive tuberculosis were identified in each survey, and their susceptibility to Isoniazid and Streptomycin was determined.

Results : Between 1968 and 1986, initial drug resistance to Isoniazid increased from 12.5% to 20.7% in prevalence cases, at an average annual rate of 3.1%. For Streptomycin, the increase was from 6.4% to 12.1% at the rate of 4.9% per annum. In incidence cases, the corresponding annual rate of increase was 3.8% for Isoniazid and 7.4% for Streptomycin. In the subset of the population, that was surveyed in 1991-92 and 1994-96, there was some evidence of a decline in the proportion of resistant cases after 1984-86.

Conclusion : There was a steady increase in the magnitude of initial drug resistance in the community between 1968 and 1986, which probably indicates an unsatisfactory tuberculosis programme during the period.

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