Introduction. Typhoid fever, caused by Salmonella enterica serovar Typhi, is a systemic infection. Approximately 40 cases occur annually in Japan, most of which are imported. In August 2023, a researcher engaged in phage typing of S . Typhi was diagnosed with typhoid fever. Case Presentation. A 48-year-old man presented with high fever, diarrhoea, malaise and loss of appetite. Initial findings, including liver dysfunction and severe inflammation, led to a suspected diagnosis of autoimmune disease. However, blood cultures identified S . Typhi, confirming typhoid fever. Comparative genomic analysis demonstrated clonality between the strain handled in the laboratory and the patient isolates, indicating a laboratory-acquired infection. Conclusion. This case underscores the need for ongoing vigilance regarding the risk of laboratory-acquired infections and highlights the value of whole-genome sequencing for tracking. It would be also emphasized that this is the first reported case in Japan linked to phage typing, a conventional typing method for S . Typhi. This raises the urgency of transitioning from phage typing to genotyping and recommends mandatory typhoid vaccination for laboratory personnel working with S . Typhi to minimize infection risk.
Morita et al. (Sun,) studied this question.