Outbreak Investigation
Investigation of a Multi-County Paratyphoid Fever Outbreak in Taiwan, October–November 2022
DOI: 10.6524/EB.202605_42(10).0001Tien-Hao Chang1*, Angela Song-En Huang1, Wan-Chin Chen2, Jui-Hsin Chang3, Chih-Kai Chang4, Pei-Yuan Wu5, Ying-Shu Liao5, Chien-Shun Chiou5
2026 Vol.42 NO.10
Correspondence Author： Tien-Hao Chang1*
- 1Office of Preventive Medicine, Taiwan Centers for Disease Control
- 2Division of Infection Control and Biosafety, Taiwan Centers for Disease Control
- 3Northern Regional Center, Taiwan Centers for Disease Control
- 4Central Regional Center, Taiwan Centers for Disease Control
- 5Center for Diagnostics and Vaccine Development, Taiwan Centers for Disease Control
Abstract：
Paratyphoid fever is caused by the bacteria Salmonella enterica subsp. enterica serovar Paratyphi A, S. Paratyphi B, or S. Paratyphi C. During 2017–2021, an annual average of one locally-acquired paratyphoid fever case was reported in Taiwan. In October 2022, the Taiwan Centers for Disease Control was notified of six patients with paratyphoid fever in five different counties who had no apparent epidemiological linkages. We conducted an investigation to verify the outbreak and identify possible infection sources. Among the cases, no common food exposures were found. All 38 close contacts had negative stool cultures, although two were symptomatic. None of the 19 food handlers from three suspected restaurants reported symptoms; all 19 stool cultures were negative. Five of six isolates had indistinguishable pulsed field gel electrophoresis (PFGE) patterns. Whole genome sequencing (WGS) of the six isolates had the same core-genome single-nucleotide polymorphism (cgSNP), indicating that all 6 cases formed a cluster. It is recommended that future paratyphoid outbreak investigations prioritize the timely collection of relevant specimens, improve the accuracy of dietary history taking, and promote the routine application of whole genome sequencing to enhance outbreak detection and traceback.
