Search

Based on studies carried out by the author and his associates in areas of Japan and South Asia where malayan and bancroftian filariasis is endemic, this paper recommends methods for use in microfilaria surveys and in the analysis of data obtained in such surveys. The author recommends the use of measured blood samples of 30 mm(3), with which 3 linear smears are made on slides. The blood films are then stained with azure II and eosin. Microfilarial counts made with such smears are, it is claimed, simpler, less expensive, and more reliable than those made with round, thick smears. Furthermore, the use of 3 smears from each person permits the calculation of correction factors, by means of which the detection rates that would be obtained by the use of different volumes of blood may be calculated.Information obtained by the use of this method has proved to be of great use in epidemiological studies of filariasis in endemic areas, in comparing the prevalence of the disease in different populations, and in evaluating the results of control measures. Different ways of recording and classifying the results are described, and the frequency distribution of microfilarial densities is analysed.

Nation-wide tuberculosis prevalence surveys were conducted by the Japanese Ministry of Health and Welfare in 1953, 1958 and 1963, using the stratified random sampling method. Follow-up surveys were made on one-third of the areas surveyed in the previous year in 1954, 1959 and 1964. In this paper the results of surveys in 1959, 1963 and 1964 are compared with those of previous surveys.The prevalence of active tuberculosis of all forms fell from 3.4% in 1953 and 3.3% in 1958 to 2.1% in 1963. The decrease in active tuberculosis was more marked in the most advanced forms of bacteriologically positive cases and cavitary tuberculosis which fell from 0.75% in 1953 to 0.55% in 1958 and to 0.19% in 1963, and from 0.6% in 1953 to 0.4% in 1958 and 0.3% in 1963, respectively. The prevalence ratio showed a marked fall in the under 50 years age-group but remained on a similar level in the over 50 years age-group.The incidence of pulmonary tuberculosis fell from 0.37% in 1954 to 0.23% in 1959 and to 0.17% in 1964, the age-specific incidence being high in the 0-4 years and 30-44 years age-groups in the 1954 survey. In subsequent surveys the incidence fell in the younger age-groups and increased in the older.Thus, the epidemiological situation in Japan has been improving in recent years except in groups-i.e., older age-groups, unemployed and self-employed persons, merchants, artisans and employees in small enterprises-in which the coverage of tuberculosis control programmes was insufficient.