Okayama Igakkai Zasshi (Journal of Okayama Medical Association)

Epidemiological Studies on the Epidemic of Japanese B Encephalitis during 7 years of 1959-1965 in Western Japan (with Special Reference to Okayama, Tottori, Hyogo, Kochi, Ehime, Kagawa, Tokushima, Miyazaki, and Aichi Prefecture)

The Epidemiological Study of Japanese B Encephalitis in Japan, Part 3

Masana Ogata, Norihiko Hasegawa, Yoshiaki Takagoshi, Toru Takehisa, It ...

1966 Volume 78 Issue 1supplement Pages 1-29
Published: January 30, 1966
Released on J-STAGE: August 24, 2009

DOIhttps://doi.org/10.4044/joma1947.78.1supplement_1

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1) Data has been presented on the trend of Japanese B. Encephalitis from 1959 to 1965 in Okayama, Miyazaki, Kagawa, Tokushima, Kochi, Ehime, Hyogo and Aichi Prefectures, middle and western parts in Japan.
2) The prevalence started from Miyazaki, most southern part in Japan, and progressed succesively to Kochi, Okayama, Tottori and Miyagi. The difference in date between Okayama and Miyazaki was 20 days, Okayama and Kochi was 10 days, Okayama and Tottori, adjacent to northern part in Okayama, was 2 days and also the difference in date between northern and southern part in Okayama was 7 days. We woulld like to call this phenomenon “Tendency towards northeast”.
This tendency can be arranged in the order of its average atmospheric temperatures. However, there is no correlation between the date of incidence in each year and the temperature gradient.
3) From 1950 to 1959, the incidence rate was higher in the southern district than in the northern district, and from 1960 to 1965 it became higher in the northern district than in the southern district of Okayama Prefecture.
4) The incidence rate by age from 1960 to 1965 was higher in the old over 60 ages in northern district and in the child below 10 ages in the southern district of Okayama Prefectuve. A marked tendency to decrease the incidence rate in the child has been seen since 1959. This downward tendency would be caused by the J. B. E vaccination.
5) There is some indication from the geographycal distribution that the prevalence spreaded from focus to other villages contiguously, except for the town.
6) In past five years the district where the incidence rate exceeded over 10/100, 000 peoples three times or exceeded over 20 was shown by the following districts,
Northern district in Okayama. Prefecture
Eastern and western district in Tottori. Prefecture
Northwest district in Hyogo. Prefecture
East and west parts in Kochi. Prefecture
Southern district in Miyagi. Prefecture
In general, the high incidence was observed in the plain near mountain or the basin but not in the town.
7) There is a phenomenon that when the incidence rate was over 20 in the year, the incidence rate next year became low.

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Haemoagglutinin Inhibition Test of Japanese B Encephalitis in the Serum of Swine, Heron and Inhabitants in Okayama Prefecture

The Epidemiological Study of Japanese B Encephalitis in Japan, Part 4

Masana Ogata, Norihiko Hasegawa, Katashi Hitomi, Kengo Awaya, [in Japa ...

1966 Volume 78 Issue 1supplement Pages 31-39
Published: January 30, 1966
Released on J-STAGE: February 16, 2009

DOIhttps://doi.org/10.4044/joma1947.78.1supplement_31

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Haemoagglutinin inhibition test (HI test) of Japanese B Encephalitis was conducted in the people, pigs and heron that lived in Okayama Prefecture in 1966, and following results were obtained.
1. The first epidemic in the pigs in the year was shown on the middle of June and 20% of the pigs showed positive HI test, 1:160 or above. The second wide epidemic in the pigs was also observed in the begining of August and all of the pigs showed positive HI test. The above results were obtained from the HI test of pigs in the slaughterhouses, and the HI test of serum obtained from the ear veine of pigs in the breeding house also showed similar results.
2. On the HI test of night heron, caught at the nests in the mountain at Tsudaka Village, half of heron showed positive reaction. However HI test of white heron lived in the nests near the nests of night heron, showed negative reaction.
3. On the HI test of inhabitants in Higashiawakura Village, where the patient of Japanese B Encephalitis has not been found, a half of the inhabitants injected Japanese B Encephalitis vaccine showed positive reaction and the non vaccinated group showed negative reaction.
4. The high specific active antibody of HI reaction was prepared from pig γ globulin by DEAE cellulose column çhromatography.

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Epidemiological Studies on the Epidemic of Japanese B Encephalitis during Past 15 Years (1950-1964) in Tottori Prefecture

The Epidemiological Study of the Japanese B Encephalitis in Japan, Part 5

Iwao Teratani, Masana Ogata

1966 Volume 78 Issue 1supplement Pages 41-49
Published: January 30, 1966
Released on J-STAGE: February 16, 2009

DOIhttps://doi.org/10.4044/joma1947.78.1supplement_41

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In their epidemiological studies on the epidemic of Japanese B Encephalitis that broke out in Tottori Prefecture during past 15 years (1950-1964), the authors obtained the following results.
1) Every year's morbidity rate except 1954 in Tottori Prefecture was higher than that in all Japan.
2) As for the season of prevalence, the end of August or the beginning of September was a peak of prevalence.
3) In the next year of a high epidemic year, there was tendency that the peak of prevalence expressed as median was later coming than that of the former year.
4) As for the district of prevalence, the morbidity rate of Sakaiminato City is the smallest in Tottori Prefecture during past 15 years.
5) As for the sex, male morbidity rate was higher than female one.
6) Concerning age, rate of morbidity in children below 10 years of age has been decreased, and that in people above 60 years of age has been increased during past 5 years.

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ELECTROENCEPHALOGRAPHIC STUDY ON JAPANESE B ENCEPHALITIS

with special reference to applicatiou of electroencephalography to diagnosis and prognostication

Eiji Hamamoto, Shunsuke Ohtahara, Yoshito Takabatake, Yukio Mukai, Eij ...

1966 Volume 78 Issue 1supplement Pages 51-59
Published: January 30, 1966
Released on J-STAGE: February 16, 2009

DOIhttps://doi.org/10.4044/joma1947.78.1supplement_51

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It is the purpose of this paper to present an electroencephalographic study on Japanese B encephalitis for elucidating its pathophysiology, aiding its diagnosis and treatment and for evaluating its prognosis.
Electroencephalograms of 19 patients admitted to our clinic were investigated in their courses of Japanese B encephalitis.
We clinician have had only one method to know cerebral pathology in encephalitis, that is to judge on neurological signs and symptoms, and yet it is not entirely reliable. However, EEG can disclose pathological process which has been taken place and is going on in the acute stage in the brain of the patient and we can grasp whole pathology objectively by EEG. Besides this, we suppose we can know the prognosis of the patients more accurately by reading EEG than other conventional methods.
In the acute stage, there is a bilateral symmetric monorhythmic continuous high voltage delta activity of 1 to 2.5c/s with frontal dominancy. This pattern is very characteristic of the Japanese B encepaalitis. This finding suggests that the primary lesion of this disease is located in the subcortical structure, especially in the ascending reticular formation of the brain stem.
Electroencephalographic findings in the process of Japanese B encephalitis are illustrated in Table 1
Patients recover from encephalitis with the EEG findings in the order of 1) to 7) (from up to down) shown on the Table 1. in his EEG if the patient follows uneventful course.
We have confirmed it takes about 1 year for the patient to follow the above-mentioned process and finally attain normal EEG. This is quite different from in the case of aseptic meningitis.
If the patient fails to follow the above-mentioned course and stop at some stage in the middle, we consider this patient has much possibility to develop mental deficiency or other nourological sequelae.
In the case that patient shows epileptic discharge in his EEG during convalescent period, we predict this patient will develop clinical epilepsy sooner or later.
We, therefore, think it very important to have successive EEG study at least for four years on the patient with encephalitis even after his clinical abnormality clears up.

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Electron Microscopic Study on Japanese B Encephalitis Virus

Kiyoshi Hiraki, Zensuke Ota, Shinya Suzuki, Kenji Takahashi, Masahito ...

1966 Volume 78 Issue 1supplement Pages 61-68
Published: January 30, 1966
Released on J-STAGE: February 16, 2009

DOIhttps://doi.org/10.4044/joma1947.78.1supplement_61

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The ultrastructure and developmental process of Japanese B encephalitis virus were studied by electron microscopy in porcine kidney stable (PS) cells infected with the Mukai strain of Japanese B encephalitis virus. The virus and PS cells were kindly supplied by Dr. Y. Kanda Inoue at the Virus Institue of Kyoto University. PS cells were cultivated in bottles containing 10% calf serum and 0.5% lactalbumin hydrolyzate in Earle's balanced solution. Titration of cellassociated virus was estimated by cytopathic effect. At various intervals following infection, the cells were fixed in buffered 1% osmium tetroxide solution, embedded in methacrylates and cut on a Leitz ultramicrotome. After sections were stained in saturated uranyl acetate solution, they were observed in the Hitachi type HU ll electron microscope.
Japanese B encephalitis virus particles were hexagonal in thin sections and approximately 40 mμ in the longest diameter, composed of the outer membrane, 30Å in thickness, viroplasm, 30Å in thickness and an electron-dense nucleoid, 25 mμ in diameter, After the virus particles developed in the process of budding on the wall of the cytoplasmic vacuole, they were densely packed in the vacuole usually in random arrangement and occasionally in crystalline arrays. The vacuole containing the virus particles gradually migrated to the cell surface and liberted the particles to the exterior of the cell through a narrow canaliculus which was formed between the vacuole and cell surface.

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The seasonal distribution of mosquitoes and the incidence of Japanese B encephalitis at Okayama and Kurashiki in 1963

Seiiti Inatomi, Kazuo Itano, Mitiya Kimura, Taneo Tsubota, Yosihiro It ...

1966 Volume 78 Issue 1supplement Pages 69-75
Published: January 30, 1966
Released on J-STAGE: February 16, 2009

DOIhttps://doi.org/10.4044/joma1947.78.1supplement_69

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Mosqnitoes were collected by light-trapping twice a week during nights from May through September, 1963, totally 30 times from two spots of Kurashiki City and 32 times from one spot of Okayama City.
The number of mosquitoes collected was 1, 563 and 2, 882 from Hama and Mizushima in Kurashiki City respectively, and 9, 185 from Okayama City.
Culex tritaeniorhynchus first occurred at the end of May at Mizushima, in the middle of June at Okayama, and in the beginning of July at Hama, and reached their peak in July, on the 23rd at Mizushima, on the 29th at Okayama, and on the 30th at Hama.
While the first incidence of Japanese B encephalitis at Okayama and Mizushima was reported approximately three weeks after the maximum occurrence of the mosquito, it was as early as on the 20th of July at Hama being ten days ahead of the peak.

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The seasonal distribution of mosquitoes and the incidence of Japanese B encephalitis at Okayama aud Kurashiki in 1964

Seiiti Inatomi, Kazuo Itano, Mitiya Kimura, Taneo Tsubota, Yosihiro It ...

1966 Volume 78 Issue 1supplement Pages 77-84
Published: January 30, 1966
Released on J-STAGE: February 16, 2009

DOIhttps://doi.org/10.4044/joma1947.78.1supplement_77

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Mosquitoes were collected by light-trapping twice a week during nights totally 38 times from Okayama City, 25 times from Ichinomiya near Okayama City, and 34 times and 40 times from Mizushima and Hama in Kurashiki City, and the number of mosquitoes trapped was 5, 209, 331, 144, 782, and 4, 395 respectively.
The maximum occurrence of mosquitoes was on the 10th at Hama, on the 13th at Okayama, on the 17th at Mizushima in July, and on the 3rd of August at Ichinomiya.
The incidence of Japanese B encephalitis was reported three weeks after the maximum occurrence of mosquitoes in each spot.

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