1957 Volume 31 Issue 7 Pages 452-461
With the complement-fixation test modified by Casals and Palacios, the field works have been also carried out in Japan. The results vary according to the affected areas and the investigators. The infection rate however, is estimated at about 10-30% around the period of epidemic in summer. With 862 inhabitants in the damp fields of Toyama prefecture, the test was performed at several time intervals, the most frequent being 8 times with one person. The total amounted to 3338. Excluding 111 cases which showed anticomplemental and non-specific reactions, 3227 cases were examined on the complement-fixation test. The results were as follows:
Antibody titer (0) 2680 (83.0%)
Antibody titer 2 (+) 315 (9.8%)
Antibody titer 4 (+) 205 (6.3%)
Antibody titer 8 (+) 23 (0.7%)
Antibody titer 16 (+) 4 (0.1%)
Antibody titer 32 (+) 0
Consequently, 16.1% demonstrtaed over 2 (+), 7.2% over 4 (+) and 0.8% over 8 (+).
According to our classification I-IX Group by the neutralisation test with 103 persons, I group (with almost no antibody titer) consisted of 20 persons, III group 13, and IV-IX group (with over 1.7 neutralisation in dex) 62. The highest neutralisation index was 4.4, and only one person proved to have over 4.0 index. One may conclude from the above results, that the encephalitis virus continued to contaminate a fairly great number of population every year, though no encephalitis case was reported during the years of investigation in this area.
