Outbreaks of food poisoning caused by pathogenic halophilic bacteria in Tokyo during 1961 were studied epidemiologically and bacteriologically with the following results.
1. A total of 224 outbreaks of food poisoning were reported in Tokyo during 1961, involving 5, 206 persons. Of them, 73 were of known etiology, affecting 2, 898 persons. Pathogenic halophilic bacteria were incriminated in 56 outbreaks, or 76.7 per cent of the total outbreaks of bacterial food poisoning, which involved 2, 560 persons, or 91.8 per cent of the total patients suffering from the bacterial food poisoning. These data indicate that pathogenic halophilic bacteria play a more important role in causing food poisoning than any other microorganism.
2. Uncooked seafood was given first rank among the causes of halophilic bacterial food poisoning, inducing 30 outbreaks (54.0 per cent) of the 56 mentioned above. Cooked seafood was incriminated in 8 outbreaks, vinegared seafood in 2, processed seafood in 3, and miscellaneous food in the remainder of the 56 outbreaks.
3. In the food poisoning of this etiology, the period of incubation was 13 hours on the average. Of the clinical symptoms manifested, diarrhea never failed to appear and abdominal pain was quite frequent. Pyrexia, headache, nausea, and vomiting were exhibited by about 35 per cent each of the patients involved. Judging from the principal symptoms and the period of incubation, food poisoning caused by pathogenic halophilic bacteria is of infectious type.
4. A total of 386 strains of bacteria were isolated from the outbreaks of food poisoning of this etiology. When they were classified after TAKIKAWA, 134 strains (38.4 per cent) were of type 2, 75 (19.5 per cent) of type 22 and 35 (9.1per cont) of type 17.A high frequency of occurrence was seen restrictedly in the three. No strain was found to be of type 7, 9, 11, 12, or 20. One to 4 strains belonged to each of the other types of TAKIKAWA's classification. When the 386 strains were rearranged according to 0 antigens they possessed, 134 stains (38.4 per cent) belonged to the 0-2 group and 118 strains (30.6 per cent) to the 0-4 group.
5. Among 56 outbreaks of collective food poisoning involving a considerable number of persons, there were 17 outbreaks from which only bacteria of a single type were isolated. From the remaining 39 outbreaks were isolated bacterial strains of type 2 to 4 according to the classi fication of 0 antigens. Moreover, 2 bacterial strains of other types than those of 0 antigen classification mentioned above were isolated from 4 patients involved in these outbreaks.
6. A total of 2, 718 foodhandling persons were examined for carriers. As a result, a strain of type 0-6 and another of unknown type of pathogenic halophilic bacteria were isolated from them. The rate of detection of carriers is much lower than that of Shigella among healthy people.
7. During a period from August, 1961, to December, 1961, a total of 266 patients of sporadic diarrhea were examined for etiological organisms. From them, 22 strains of pathogenic halophilic bacteria were isolated exclusively during a four month period of July to October. None of the bacteria was detected from them durig the other months of the year.
It is likely that those bacteria play an important role in the occurrence of diarrhea in summer. In addition, 16 cases of positive detection of Shigella were reported during the same period of the present survey.
Of the 16 strains, 12 weas isolated in all the months of the year, except July, August, and September.

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Titration of the smallpox vaccines released in 1959, 1960 and 1961 was carried out by pock-counting method and the reduction in virus titer during the storage period by the regulation of the Japanese Government was investigated. Correlation between virus titer in terms of PFU/ml and the rate of positive take in human vaccination was also examined, and the following conclusion was obtained.
1) Hundred per cent positive take in the primary vaccination of infants can be expected rby the multiple puncture method with a vaccine having a potency of more than 107.24 PFU/ml.
2) A reduction in potency on the date of expiration was less than 100.75 PFU/ml, if the vaccine was stored under the conditions indicated by the minimum requirement of biological products.
3) From the above it can safely be said that a vaccine having a potency of more than 108.00: PFU/ml at the time of the national assay will give 100 per cent positive take in the primary vaccination on the date of expiration of the vaccine.

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