2023年1-3月疑似急性A型肝炎IIIA型群聚事件調查

Investigation of A Suspected Hepatitis A Outbreak Associated with Genotype IIIA, Taiwan, January-March 2023

2023年3月衛生福利部疾病管制署檢驗及疫苗研製中心通知新增6例A型肝炎個案之基因分析結果，其中5例為本土個案，基因型皆為IIIA且親緣性相近，疑似本土急性A型肝炎IIIA型群聚。本調查採病例對照研究，針對5例A型肝炎IIIA型病例進行電話訪問，分析其發病前一月飲食史與國人飲食史之差異，結果顯示食用生魚片、生蝦等生食海鮮為本次疑似急性A型肝炎IIIA型群聚之可能風險因子，但並未發現與特定產品相關。建議持續監測全國IIIA型急性A型肝炎個案發生情形，注意飲食衛生，避免生食，無A型肝炎抗體者及高風險族群可考慮接種疫苗，以降低感染急性A型肝炎之風險。

In March 2023, Taiwan Centers for Disease Control identified genetic analysis results of six newly identified patients of acute hepatitis A, of which five were indigenous, and all belonged to genotype IIIA with high genetic similarity. Previously, the prevalent genotype in locally acquired hepatitis A cases was IA, suggesting a potential outbreak of genotype IIIA acute hepatitis A. The preliminary investigation excluded the potential risk of intravenous drug use or needle sharing. We conducted a case-control study; a case was defined as an individual with indigenous acute hepatitis A infection of genotype IIIA, demonstrating high genetic similarity as confirmed through genotyping in March 2023. We interviewed five cases, assessing their demographics, symptoms, and dietary history a month before onset or diagnosis. Statistical analysis using Fisher's exact test compared findings to the general population. Consuming raw fish and shrimp in the month before illness was identified as a potential risk factor, but the specific source of infection remains unidentified. Continuous surveillance of genotype IIIA acute hepatitis A cases is recommended. Public awareness of food hygiene, particularly avoiding the consumption of raw seafood, is essential. Individuals without hepatitis A antibodies or at high risk should consider vaccination to reduce the infection risk.