Tuberculous infection in a rural population of south India: 23-year trend.

A survey was conducted in Bangalore district of south India between February 1984 and January 1986 to study the tuberculosis infection rate. The data from this survey, along with the information derived from the earlier ones in the same area conducted between 1961-1968, have been used in the report to study the trend of tuberculosis. Tuberculin test results in 0- to 14-year-old unvaccinated children from each survey were distributed, and based on the antimode, infected persons were identified. The standardized prevalence rates in population from the surveys were converted into risk rates by using the TSRU methodology and compared. The average annual risk of infection of 1.1% observed in 1961 declined to 0.61% in 1985, representing a decline of approximately 37% in nearly 23 years. This amounted to an average decline of 3.2% per annum over the period. The trend probably represented a natural dynamics. Whether organized intervention played some role could not be commented upon. Similar studies in other parts of the country are recommended in order to have information on the trend in the country as a whole.