Abstract
The epidemiological examination on Yato-byo was performed at east-Mikawa district in Aichi Prefecture where in 1952 one case of this disease was found in south-Nagoya without any succession.
Results
1) The ticks living upon 9 wild rabbits, caught at various areas of east-Mikawa-district, were examined. They were mostly Haemaphysalis flava Neumann and Ixodes persuleatus persulcatus and none of Ixodes japonensis was found. The numbers of Haemaphysalis fl. N. were 118, Ixodes p. p. 110. The mites were found mainly from the rabbits seizured at Gamagori area.
2) Fifteen hunters were collected and six out of fifteen came from Gamagori area and 9 from Kosei area. Three out of formerly described six showed positive intradermal reactions. And only one out of this three had positive aggultination test.
This results suggest us that in Gamagori area there will be a large number of persons who have suffered from Yato-byo not positively but latently.
3) As described above, Aichi Prefecture had previously Yato-byo only once. This person had re-examination nine years after his first onset. The intradermal reaction showed strong positive again and the aggulitination titre was 1:40.
