Clinical investigations were carried out with 28 patients of a mass incidence of Izumi fever which broke out on November 1954 in our nurse dormitory. The main clinical manifestations consisted of fever and exanthema. Furthermore, the following symptoms were experienced; headache, chill, perspiration, arthralgia, lumbago, anorexia, nausea, vomiting, stomachache, etc.
The fever curve showed mostly one or two peaks, however, in a few cases three peaks or an irregular type. The fever period lasted 9 to 36 days, the most frequent being 14 to 27 days. The exanthema was almost the same as the hitherto reported ones. They appeared namely as primary, secondary and tertiary eruption and showed erythematous, scarlatinar, measle-like or mixed form. The former two were particularly often encountered. The desquamation was observed in 2/3 of the cases. The liver was swollen in a half of the cases and went parallel with the exanthema.
The spleen was palpable only in a few cases, whereas the lymph nodes were palpable almost in a half. Uroblilinogen was positive in the urine in all cases and the blood sedimentation rate was moderately accelerated in general. Among liver function tests C. C. F. was positive in the beginning in all cases, but contrary to that the Takata reaction and the T. T. T. turned out positive only in a few cases. It is very interesting that in nearly one half of the cases the agglutination test against Proteus Ox K turned out positive in the course of the disease. Streptococcus hemolyticus, II type after Kobayashi was isolated from the larynx in a fairly high rate. A certain relationship might be suspected between this type of staphylococcus and this incidence. Intravenous injection of Tetracin seemed to be effective.