MMWR Morb Mortal Wkly Rep. 2020 Jul 3;69(26):820-824. doi: 10.15585/mmwr.mm6926a3.
Los Angeles County comprises 4,058 square miles and is home to approximately 10 million residents (1), an estimated 59,000 (0.6%) of whom experience homelessness on a given night (2). In late 2018, Los Angeles County Department of Public Health (LAC DPH) was notified of a case of hepatitis A virus (HAV) infection in a person experiencing homelessness. LAC DPH conducted an investigation to determine the source of infection, identify additional cases, and identify contacts for postexposure prophylaxis (PEP). Over the next week, LAC DPH identified two additional hepatitis A cases in persons experiencing homelessness who knew one another socially and were known to congregate at a specific street intersection. To identify and respond rapidly to additional outbreak-associated cases, LAC DPH implemented enhanced surveillance procedures, including immediately obtaining specimens for molecular testing from all patients with suspected hepatitis A in the same geographic area. Enhanced surveillance identified four additional cases in persons linked to a senior living campus within two blocks of the intersection where the initial three patients reported congregating. These four cases were linked to the cluster in persons experiencing homelessness through HAV genotyping. Overall, DPH identified seven outbreak-associated hepatitis A cases during October 2018-January 2019. The DPH response to this community hepatitis A outbreak included conducting vaccination outreach to persons at risk, conducting environmental health outreach to restaurants in the outbreak area, and issuing health care provider alerts about the increased occurrence of hepatitis A. Implementation of near real-time molecular testing can improve hepatitis A outbreak responses by confirming HAV infections, linking additional cases to the outbreak, and informing the targeting of prevention efforts.
洛杉矶县占地 4058 平方英里，拥有约 1000 万居民（1），据估计，其中有 59000 人（0.6%）在特定的夜晚无家可归（2）。2018 年末，洛杉矶县公共卫生部（LAC DPH）接到报告，称一名无家可归者感染了甲型肝炎病毒（HAV）。LAC DPH 展开调查，以确定感染源，发现更多病例，并确定接触者接受暴露后预防（PEP）。在接下来的一周内，LAC DPH 在另外两名无家可归者中发现了两例甲型肝炎病例，他们彼此相识，且已知在特定的街道交叉口聚集。为了迅速发现更多与疫情相关的病例，LAC DPH 实施了强化监测程序，包括立即从同一地理区域内所有疑似甲型肝炎患者身上采集样本进行分子检测。强化监测在距离交叉口两个街区内的一个老年人生活园区发现了另外四例病例。这些病例与最初报告聚集在交叉口的 3 名患者有关。通过 HAV 基因分型，这些病例与无家可归者中的聚集病例有关。总体而言，DPH 在 2018 年 10 月至 2019 年 1 月期间发现了 7 例与疫情相关的甲型肝炎病例。DPH 对此次社区甲型肝炎疫情的应对措施包括对高危人群进行疫苗接种宣传，对疫情地区的餐馆进行环境卫生宣传，并向卫生保健提供者发出关于甲型肝炎发病率上升的警报。实施近乎实时的分子检测可以通过确认 HAV 感染、将更多病例与疫情联系起来以及为预防工作提供目标，从而改善甲型肝炎疫情的应对措施。
