The clinical, biochemical and bacteriological studies on the bovine leptospirosis were performed. Twenty one native black cattles with hemoglobinuria caused by leptospira infection, were used for experimental materials.
The results obtained were as follows:
1) The first sign of the infection was hemoglobinuria. Anorexia and depression were sometimes observed 1-2 days preceding to hemoglobinuria. Hemoglobinuria was accompanied usually with remarkable anemia and moderate leucocytosis. Fever, jaundice conjunctivitis and constipation were also observed in severe cases. In recovered cases, hemoglobinuria disappeared within 2-6 days, it took about 40 days to 4 months for recovery Apf anemia.
2) Proteinuria was accompanied usually with hemoglobinuria. While hemoglobinuria was observed by the infected cattles, pH of urine tended to be lowered and serum protein, to decrease.
3) The above mentioned methods were applicated, to isolate leptospira organisms from urine of cattle with hemoglobinuria. The urinary excretion of leptospira organisms was continued for about one month after recovery of hemoglobinuria. Leptospira antibodies in the serum, however, were observed to be maintained by high titer for 4 months after recovery.

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Leptospira autumnalis, isolated from cattle, was injected to pregnant guinea pigsin oder to prove whether leptospira infection may be cause of aborion in pregnant animals or not. The results obtained were as follows.
1. Of 21 pregnant guinea pigs which were injected with leptospira, 13 abortion, 2 p premature and 6 normal deliveries were observed.
2. The age of these fetuses was presumed by the'_r body length. It was found, that all the aborted fetuses were less than 60 days of age and the premature delivery occurred at about 60th to 70th days of pregnancy. Regular parturition was observed after the complete pregnant period. Accordingly, if we used pregnant guinea pigs before about the 50th day of pregnancy, all of them would be abort.
3. Leptospira was isolated almost usually from the emulsiar mixture of kidneys and liver of dams and frequently from the uterus and placenta, while the isolation of leptospira successed only in 2 of 21 fetuses.
4. By the time when abortion, was occured the guinea pigs were classified into 4 groups: those aborted (1) at the begining of the febrile stage, (2) during the febrile stage after that, (3) after the febrile stage, and (4) later than that stage. In the first and second groups, leptospira was isolated from the kidney, uterus and placenta but not from the fetus, and in the third group, from the kidney, uterus placenta and fetus. In the fourth group it was never detected from the kidney, uterus, placenta and fetus.
5. From the results obtained, the mechanism of abortion is considered as follows. The abortion in the first group occurred mainly due to the rise of fever accompanied with leptospiremia. In the second group, abortion was caused by the fever and leptospira infection producing pathological alteration in the placenta. In the third group, death of the fetus and the degeneration of the placenta following by leptospira infection were the principal causes of abortion. In the fourth group, it seemed, that the fetus died from the above mentioned causes were delivered after longterm stay in the uterus, as semi-mummified fetus was found in some cases.

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For the purpose of producing most potent immune sera, mice and goats were hyperimmunized with the Nakayama strain of Japanese B encephalitis virus. Thereby the effects of PVL combination and partial bleeding upon neutralizing antibody titre were investigated, the results, were:
1) The sera with neutralizing antibodies of high titre were obtained by repeated injections of live and Merzonin-inactivated viruses of Japanese B encephalitis for a long period of time.
2) Combined use of PVL promoted the rise of neutralizing antibody titre, and shortened the term for hyperimmunization.
3) Hyperimmunization appeared to have a definite limit in producing neutralizing antibodies: further injections beyond that limit gave rise to no more rise in titre.
4) Partial bleeding of in followed by appropriate treatments, brings about no descent of the neutralizing antibody titre and reversely ascends the titre, then the combined PVLadministration proved also effective.
5) Normal mice kept near the ones rzceiving immunizing doses of live virus showed the rise of their neutralizing antibody titre following their growth. This rise in titre appears to be due to the inapparent infection.

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Dysentery vaccines prepared by Toshihiko OSHIRO and Matao SAITO since 1954 in Public Health Laboratory, Hyogo Prefecture by means of detoxication methods with synergic effect of 2-4% calcium chloride as well as 4% formaline proved to be safe by inoculation to nearly c75, 000 persons for these seven years.
I) The following toxic activities of the dysentery vaccine were lessened by Oshiro-and Naito's detoxicating method.
i) lethal or body weight decreasing toxicity in inoculated animals,
ii) skin-reaction developing toxicity in the skin of intradermally inoculated animals,
iii) leucocytotic toxicity in peripheral blood of intravenously or introdermally inoculated rabbits but not leucopenic toxicity.
iv) Leucocytosis in peripheral blood of rabbits by intravenous injection of the vaccine similar to the marked leucocytosis seen in tee animals by intravenous injection of epinephrine.
v) Leucocytosis in rabbits by intradermal inoculation of the vaccine similar to the marked one seen in the animals several hours after intradermal inoculation of epinephrine or cortisone.
II) The above mentioned toxic activities of the vaccine lessened by synergic effect of calcium chloride as well as formalin were regarded as different manifestations of the same substance of endotoxin, an adrenalin-like or adrenalin promoting agent of endotoxin.
III) This toxic principle related closely to adrenalin was detectable by degree of leucocytosis in peripheral blood of interdermally inoculated rabbits.

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The epidemiologic study has been carrie d out on JBE in Japan during last 15 years (1946-1960), in which its secular variations in incidence, mortality and case fatality by age, sex and locality were observed.
One of the purposes of this study was to see some secular changes of the disease after the year when the vaccination has begun to be used for the mass immunization.
The results obtained in the study were as follows:
1) Three big epidemics of JBE have occurred in Japan during the last thirty seven years. After the last epidemic of 1950 the disease has indicated a little increase of incidence rate every two years without any big outbreak.
2) During the last fourteen years the incidence rate of the disease has been 2 to 5 100, 000 population, while the death, rate 1 to 3 and case fatality rate, ca 35%. The incidence rates of both the age groups of 5-9 years and more than 60 years old are higher than any other age groups, so that the incidence curve by age shows M-form. It is always higher in male than in female, while higher the case fatality rate is higher in female, and in older age groups than other age groups.
3) The case rate of the age group of 5-14 years old indicates remarkable decrease annually, since the year of 1956 when the vaccination has been widely used in this age group.
4) Before the year of 1935 JBE attacked mostly on the older aged persons than fifty and not on the younger, so that the incidence curve appeared as S-form. Since then, the age distribution of the disease has gradually changed, and recently, it shapes M-form as mentioned adove. This is the most interesting feature of JBE during past many years from the standpoint of epidemiology. Of this phenomenon there should be many factors to be concerned. The most reasonable factor is that, before the year of 1935, the prevalence and the epidemization of the disease was very little and locally limited and the host susceptibility played a big roll, while after that year the diease has spread all over the country and mass immunity and host resistance has been very much concerned about the occurrence of the disease.
5) It is certainly imagined that there are some foci of infection in accordance with the geographycal distribution of the disease in our country.
6) It was presumed, that 73.0% of children less than 14 years old were vaccinated in Tokyo, 57.1% in Nagoya and 1.7% in Kobe.
7) The incidence rate of the age group of 5-9 years old in Tokyo has apparently decreased after the period when the vaccination had been carried out. The same decrease, in more or less, was seen in each other city also.
8) The ratio of the cases of 0-14 years old to that of more than 14 years old has also decreased year by year. 9) The significant difference has been seen between the incidence rates of both vaccinated and unvaccinated groups in Tokyo during last four years (1956-1959) except year of 1957.
10) The number of all cases admitted to the infectious hospitals in Tokyo and Yoko-hama was 425, and 37.2% of them was diagnosed by virus isolation or CF-Reaction (32>) and the other 62.8% by clinical findings.
11) The prognosis of patients during last five years was as follows:
in 185 cases of 0-14 years old
56.8% Cured completely
16.7% Sequelae
26.5% Death
in 134 cases of more than 15 years old
63.4% Cured completely
9.0% Sepuelae
27.6% Death
13) Among the vaccinated patients, 12.1% of those were completely cured, 14.0% cured with sequelae and 9.3% were dead.
There was no significant difference of the prognosis between the vaccinated (37 cases) and the unvaccinated groups (282 cases).
14) It was estimated, that 17.7% of patients and 28.8% of control persons were vaccinated. The difference of vaccination status between the two groups was apparently significant. (X²= 6.38)

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