2015年HIV感染者急性桿菌性痢疾群突發之流行病學調查

Abstract

背景及目的：2015年2月起，國內出現本土桿菌性痢疾的疑似群聚事件，案例多為正值性活躍期之男性且有愛滋病毒感染之病史。本研究目的為探討此波疫情之流行病學特徵及危險因子。 方法：本研究以疾管署「法定傳染病監測系統」連結「傳染病疫情調查系統」及「慢性傳染病追蹤管理系統」，系統性收集所有在2015年1月1日至2015年12月31日期間確診為桿菌性痢疾本土病例，且確診時為已知HIV感染者或確診後15天內新診斷HIV感染之個案，分析其通報時間、居住地域、人口學特徵及HIV個案管理狀態。為探討此波疫情之危險因子，本研究從全國已通報HIV但未罹患桿菌性痢疾者中選取對照組。對照組選擇原則為針對每一病例，依照以下四項條件以1:5比例進行個別配對：年齡（±5歲）、性別、HIV診斷日（±90天）、居住城市。我們進一步以結構化問卷對病例及對照組進行電話訪談，以釐清危險行為，並以邏輯斯迴歸進行統計分析。 結果：2015年全國共通報HIV合併本土桿菌性痢疾39例，皆為男男間性行為者，年齡介於22到47歲間，無共同暴露之飲食和社交場所。病例多為未婚 (37例，94.9%)，從事服務業 (21例，53.8%)，有28例 (71.8%) 居住於台北都會區 (台北市及新北市)。多變項邏輯斯迴歸分析顯示HIV感染者罹患桿菌性痢疾的危險因子為：於HIV照護體系內失聯一年以上（adjusted odds ratio [aOR]: 7.45, 95% CI: 1.68-32.93）、最近病毒量 ≥400 copies/mL（aOR: 2.86, 95% CI: 1.08-7.53）、曾通報梅毒（aOR: 2.73, 95% CI: 1.05-7.15）、及曾通報阿米巴痢疾（aOR: 9.43, 95% CI: 1.81-49.06）。問卷調查成功訪談病例組20人及對照組60人，多變項邏輯斯迴歸分析顯示與罹患桿菌性痢疾相關的危險行為包括：舌肛吻 (aOR: 5.70, 95% CI: 1.03-31.58)、過去一年內在性行為時曾使用RUSH (aOR: 6.34, 95% CI: 1.32-30.52) 以及過去一年內在性行為時曾使用安非他命 (aOR: 9.95, 95% CI: 1.97-50.42)。 結論： 2015年HIV感染者急性桿菌性痢疾疫情係經由男男間口肛性行為傳染。若在性行為時使用RUSH或安非他命等藥物，或在HIV個管系統失聯一年以上，風險將會更高。在防治上，需針對高風險族群進行安全性行為衛教宣導，使民眾充分了解口肛交傳染桿菌性痢疾的風險。醫師須了解桿菌性痢疾可經HIV高風險性行為傳播，並建議所有新診斷急性桿菌性痢疾的病患均應接受HIV篩檢及諮商。

Background and purpose: Since February 2015, a suspected cluster of domestically-acquired shigellosis has been identified in Taiwan. Most cases occurred among sexual active males with underlying HIV infection. We aim to characterize this outbreak and identify the risk factors through case-control study. Method: We systematically identified all newly reported HIV-shigellosis cases during January 1, 2015 to December 31, 2015, using national surveillance databases. We analyzed the temporal trend, geographical distribution, demographic characteristics, and status in HIV case management. To identify risk factors, each HIV-shigellosis case was matched to 5 controls (notified HIV patients without shigellosis) individually by age (±5 years), date of HIV diagnosis (±90 days), and residing city/county. We further used telephone interview with structured questionnaire to identify behavioral risk factors of cases and controls. We use logistic regression for statistical analyses. Result: We identified 39 HIV-shigellosis cases, the majority are young, unmarried men who have sex with men (MSM) in metropolitan area. There was no common exposure to food or water. The 39 HIV-shigellosis cases were matched to 195 control HIV patients. We successfully interviewed 20 cases and 60 controls, after obtaining informed consent. Multiple logistic regression analyses identified following risk factors: loss to follow-up in HIV case management (adjusted odds ratio [aOR]: 7.45, 95% CI: 1.68-32.93), recent HIV viral load ≥400 copies/mL (aOR: 2.86, 95% CI: 1.08-7.53), past syphilis (aOR: 2.73, 95% CI: 1.05-7.15), past amoebiasis (aOR: 9.43, 95% CI: 1.81-49.06）, oral-anal sexual contact (aOR, 5.70, 95% CI: 1.03-31.58), use of RUSH during sexual encounters (aOR: 6.34, 95% CI: 1.32-30.52), use of amphetamine during sexual encounters (aOR: 9.95, 95% CI: 1.97-50.42). Conclusion: The acute shigellosis outbreak spread sexually via oral-anal contact. Chemosex with use of RUSH or amphetamine, and loss to follow-up in HIV care, are additional risk factors. To control the outbreak, risk of shigellosis should be part of routine sex education for sexually active MSM. Physicians should be aware of the association between acute shigellosis and sexual behaviors carrying high HIV risk. HIV testing and counseling is advised for all persons with newly diagnosed acute shigellosis.