In November 2022, a large outbreak of creeping disease was detected in Aomori Prefecture. Investigations included determination of the incidence and an epidemiological survey of 269 patients, pathological examination of the skin lesions in one patient, and a survey of Lake Ogawara Shirauo (Salangichthys microdon) fish that may have been involved in the outbreak of the disease.

The investigation revealed that 263 of the 269 patients surveyed had consumed uncooked or undercooked Lake Ogawara Shirauo; furthermore, Gnathostoma sp., a type of parasite, was detected in the skin lesions of one patient with creeping disease.

This suggested that the creeping disease outbreak could have been associated with Gnathostoma spp., and that the source of infection may have been Lake Ogawara Shirauo, which was consumed by many patients.

However, since no Gnathostoma spp. were detected in the Shirauo and some of the patients with the disease gave no history of eating Shirauo, the cause of the disease could not be established in this investigation. Although this outbreak is currently under control, since the source and route of infection could not be identified by the aforementioned investigation, we consider important to conduct further investigation to identify the cause in order to prevent future outbreaks.

In this study, we conducted a general investigation of 14,570 subjects who provided informed consent among hospital workers who had been vaccinated with the Pfizer's vaccine during the early phase after the vaccine received regulatory approval and were included in the priority survey (cohort survey) conducted by a Scientific Research Group of the Ministry of Health, Labour and Welfare during the initial stages of COVID-19 vaccination. The objective of the study was to investigate the long-term safety of vaccination with the Pfizer's vaccine (monovalent original strain) administered by intramuscular injection from the day after 28 days had elapsed from the last vaccination of the primary series to the end of 12 months after the last vaccination of the primary series.

The safety analysis set included 14,537 participants. The baseline characteristics of the participants were as follows: 32.97% were male and 67.03% were female, with a median age of 43.0 years. The incidence of serious adverse reactions (ARs) was 0.03% (n = 4), and included appendicitis, hemophagocytic lymphohistiocytosis, abortion threatened, and abortion spontaneous in 1 participant each. All serious ARs resolved and none were life-threatening.

The incidence of serious adverse events (AEs) was 0.83% (120 participants). The most common were COVID-19 (9 participants), abortion spontaneous (5 participants), and intervertebral disc protrusion (4 participants).

Of the 13,695 participants who received booster doses (third doses) during the observation period, 2 participants experienced serious ARs and 48 experienced serious AEs.

Of the 2,073 participants (14.26%) who underwent nucleic acid detection and antigen tests for COVID-19, 2.22% (46 participants) tested positive, and all 46 participants developed symptoms of COVID-19. Of these, 9 participants had reported as serious adverse events following vaccination and the outcomes of all events were recovered/resolved. Severe adverse events did not occur in any of the participants.

These results showed a similar trend to the results of clinical trials conducted both in Japan and overseas, and no new concerns regarding the safety of Pfizer's vaccine were identified.

Vibrio vulnificus is Gram-negative rod that is known to cause severe soft tissue infection. V. vulnificus is found in warm coastal environments. In Japan, most cases have been reported from the Kyushu area. A 75-year-old previously healthy man presented to us with septic bullous cellulitis. The causative organism was identified by blood culture as V. vulnificus. He was treated conservatively with antibiotics alone and the lesions resolved completely. V. vulnificus should be considered as a possible causative organism in cases of severe septic cellulitis, even in non-endemic areas such as the Seto Inland sea.

Listeria monocytogenes is a rare etiology of graft infection, with only 17 cases reported previously in the literature. Herein, we present a rare case of aortic arch graft infection caused by L. monocytogenes, in which workup of the patient for the infection revealed colorectal cancer.

The patient was an elderly man with a history of total aortic arch replacement and type 2 diabetes mellitus who presented to us with a several weeks' history of persistent chest and back pain and was hospitalized. Diagnostic work-up indicated an infection of the aortic arch graft. Blood cultures were positive for L. monocytogenes. Prompt relief of pain and improvement in inflammatory marker levels were observed following antibiotic therapy using ampicillin (ABPC) and gentamicin (GM) in combination. A fecal occult blood test conducted for screening was positive. Subsequent upper and lower gastrointestinal endoscopy revealed colorectal cancer, which was treated by laparoscopic surgery. As there was no evidence of metastasis, postoperative chemotherapy was deemed unnecessary. ABPC was administered continuously for a total of 6 weeks, along with administration of amoxicillin (AMPC) for 6 months. The infection was successfully controlled with the long-term antibiotic therapy and there has been no recurrence since.