2022年10-11月臺灣本土副傷寒群聚事件

Investigation of a Multi-County Paratyphoid Fever Outbreak in Taiwan, October–November 2022

副傷寒是由副傷寒沙門氏桿菌（Salmonella enterica subsp. enterica serovar Paratyphi A, Paratyphi B, Paratyphi C）感染所致。臺灣近5年副傷寒本土個案每年平均1例。疾管署於2022年10–11月期間連續接獲6例本土副傷寒個案通報。流行病學調查並未發現共同餐點或食材，38位密切接觸者糞便採檢均為陰性。19位可疑食物來源的調製者糞便檢查亦均為陰性。5案的分離菌株其脈衝電泳（pulsed-field gel electrophoresis，PFGE）圖譜無法區別彼此的差異。全基因體定序（whole genome sequencing, WGS）分析顯示這6案之菌株皆有相同core-genome single-nucleotide polymorphism（cgSNP）圖譜，研判為同一起群聚事件。建議未來副傷寒疫情調查應盡快採集相關檢體，強化潛伏期飲食史詢問技巧，並推動WGS常規化應用以提升群聚偵測與溯源能力。

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.