Tuberc Respir Dis.  1973 Jun;20(2):19-32. 10.4046/trd.1973.20.2.19.

Estimated Trends of tuberculosis Prevalence (1970~2030) by Epidemiological Simulation Model in Korea

• KMID: 2529046
• DOI: http://doi.org/10.4046/trd.1973.20.2.19

Abstract

Introduction
Writer estimated the trends of the prevalence of infections cases under the various intensities of prevention and treatment between 1970 and 2030 by utilizing the results of the two prevalence surveys conducted in 1965. 1970. and incidence survey of 1971 in Korea. ln this estimation on the trends, the epidemiological simulation model designed by Y. Azuma was used.
methods
The intensity of BCG vaccination was classified as approach B₁, B₂, B₃, B₄ which means respectively 75%. 120%. 180% and 320% of BCG coverage of newborns during a year. The intensity of treatments are classified as approach T₁, T₂, T₃, T₄ which means to cover respectively 120%. 15%. 32% and 70% of estimated patients under the treatment programme. The trents of the infections cases of pulmonary tuberculosis was estimated under following categories (1) Natural Trends (without BCG and without treatment) (2) BCG alone (without treatment) (3) Treatment alone Cwithont BCG) (4) Combined approaches (with BCG and Treatment programme) (5) Trend under a specific programme:
Results
1) Natural Trend The prevalence of tuberculosis increases gradually up to 1995 in which year the hightest prevalence of 1. 50% was observcd and there after it shows decreasing tendency. ln the year of 2030. 1t was 1. 11%. 2) The trends of infections cases with BCG alone 1n the all approaches. the rates was revealed decreasing tendenc y ofter some years increase. and the discrepanc y of decrease has become larger and in 2030. The rates were 0.81(B₁), 0.50(B₂), 0.15(B₃ ) in the approaches of B₁, B₂, B₃. and B₄ respectively, ln approach B4. the remarkably decreased rate of 0.1 % was seen already in 1910. 3) The trends of infection cases with various approaches of treatment alone. The prevalence of 0.74 in 1970, became 0.71, 0.68, 0.52, 0.16% in after 5 years treatment programme of T₁ T₂, T₃, T₄, respectively and all the approaches were commonly observed to be effective in the decrease of the prevalence. However, in approach T₁,T₂ from about the years of 2000, the rate showed the tendency of increasing again. But in the T₃, T₄, the continuous decreasing tendency of the rate were observed. 4) The trends under the combined approaches of BCG and treatment The decreasing trend was observed in all approaches and more the intensity of the programmes, the more the decreasing trend was remarkable. 5) Trends under specific programme such as the combined approaches of B₄+T₁ and B₁+T₄ , In the approach B₄+T₁ a programme with intensive prevention but neglected treatment the prevalence was observed gradual decrease while in the approach B₁+T₄, a programme with intensive treatment but neglected prevention, the fall of prevalance was observed rather earlier years of the programme. However, the final decrease rate of the prevalence was larger in the approach of B₄+T₁ than in that of B₁+T₄ .