Lancet Infect Dis. 2017 Aug;17(8):813-821. doi: 10.1016/S1473-3099(17)30249-9. Epub 2017 May 17.
An outbreak of Zika virus infection was detected in Singapore in August, 2016. We report the first comprehensive analysis of a national response to an outbreak of Zika virus infection in Asia.
In the first phase of the outbreak, patients with suspected Zika virus infection were isolated in two national referral hospitals until their serum tested negative for the virus. Enhanced vector control and community engagement measures were deployed in disease clusters, including stepped-up mosquito larvicide and adulticide use, community participation in source reduction (destruction of mosquito breeding sites), and work with the local media to promote awareness of the outbreak. Clinical and epidemiological data were collected from patients with confirmed Zika virus infection during the first phase. In the second phase, admission into hospitals for isolation was stopped but vector control efforts continued. Mosquitoes were captured from areas with Zika disease clusters to assess which species were present, their breeding numbers, and to test for Zika virus. Mosquito virus strains were compared with human strains through phylogenetic analysis after full genome sequencing. Reproductive numbers and inferred dates of strain diversification were estimated through Bayesian analyses.
From Aug 27 to Nov 30, 2016, 455 cases of Zika virus infection were confirmed in Singapore. Of 163 patients with confirmed Zika virus infection who presented to national referral hospitals during the first phase of the outbreak, Zika virus was detected in the blood samples of 97 (60%) patients and the urine samples of 157 (96%) patients. There were 15 disease clusters, 12 of which had high Aedes aegypti breeding percentages. Captured mosquitoes were pooled into 517 pools for Zika virus screening; nine abdomen pools (2%) were positive for Zika virus, of which seven head and thorax pools were Zika-virus positive. In the phylogenetic analysis, all mosquito sequences clustered within the outbreak lineage. The lineage showed little diversity and was distinct from other Asian lineages. The estimated most recent common ancestor of the outbreak lineage was from May, 2016. With the deployment of vector control and community engagement measures, the estimated reproductive number fell from 3·62 (95% CI 3·48-3·77) for July 31 to Sept 1, 2016, to 1·22 (95% CI 1·19-1·24) 4 weeks later (Sept 1 to Nov 24, 2016).
The outbreak shows the ease with which Zika virus can be introduced and spread despite good baseline vector control. Disease surveillance, enhanced vector control, and community awareness and engagement helped to quickly curb further spread of the virus. These intensive measures might be useful for other countries facing the same threat.
National Medical Research Council Singapore, Centre for Infectious Disease Epidemiology and Research, and A*STAR Biomedical Research Council.
2016 年 8 月，新加坡发现了 Zika 病毒感染疫情。我们报告了亚洲首例对 Zika 病毒感染疫情的全面应对分析。
在疫情的第一阶段，将疑似 Zika 病毒感染的患者隔离在两家国家转诊医院，直至其血清病毒检测呈阴性。在疾病聚集区部署了强化病媒控制和社区参与措施，包括加强蚊虫幼虫和成虫杀虫剂的使用、社区参与源头减少（破坏蚊虫滋生地），以及与当地媒体合作提高对疫情的认识。从第一阶段确诊的 Zika 病毒感染患者中收集临床和流行病学数据。在第二阶段，停止了医院的隔离入院，但继续进行病媒控制工作。从 Zika 疾病聚集区捕获蚊子，以评估存在哪些物种、它们的繁殖数量，并检测 Zika 病毒。通过全基因组测序后的系统发育分析比较蚊株和人株。通过贝叶斯分析估计繁殖数和推断的菌株多样化日期。
2016 年 8 月 27 日至 11 月 30 日，新加坡确诊了 455 例 Zika 病毒感染病例。在疫情第一阶段，163 例确诊 Zika 病毒感染的患者中有 163 例到国家转诊医院就诊，97 例（60%）患者的血液样本和 157 例（96%）患者的尿液样本中检测到 Zika 病毒。有 15 个疾病聚集区，其中 12 个区埃及伊蚊的繁殖率较高。对捕获的蚊子进行了 517 个蚊群的 Zika 病毒筛查；9 个腹部蚊群（2%）对 Zika 病毒呈阳性，其中 7 个头部和胸部蚊群 Zika 病毒阳性。在系统发育分析中，所有蚊子序列都聚集在疫情株系内。该株系显示出很少的多样性，与其他亚洲株系明显不同。疫情株系的最近共同祖先估计来自 2016 年 5 月。随着病媒控制和社区参与措施的部署，估计繁殖数从 2016 年 7 月 31 日至 9 月 1 日的 3.62（95%CI 3.48-3.77）降至 4 周后（2016 年 9 月 1 日至 11 月 24 日）的 1.22（95%CI 1.19-1.24）。
尽管有良好的基线病媒控制，但 Zika 病毒很容易被引入和传播。疾病监测、强化病媒控制以及社区意识和参与有助于迅速遏制病毒的进一步传播。这些强化措施可能对面临同样威胁的其他国家有用。
新加坡国家医学研究理事会、传染病流行病学与研究中心以及 A*STAR 生物医学研究理事会。
