Environmental Health Institute, National Environment Agency, Singapore, Singapore.
Lee Kong Chian School of Medicine, Nanyang Technological University Novena Campus, Singapore, Singapore.
PLoS Negl Trop Dis. 2023 Jun 22;17(6):e0011400. doi: 10.1371/journal.pntd.0011400. eCollection 2023 Jun.
This paper summarises the lessons learnt in dengue epidemiology, risk factors, and prevention in Singapore over the last half a century, during which Singapore evolved from a city of 1.9 million people to a highly urban globalised city-state with a population of 5.6 million. Set in a tropical climate, urbanisation among green foliage has created ideal conditions for the proliferation of Aedes aegypti and Aedes albopictus, the mosquito vectors that transmit dengue. A vector control programme, largely for malaria, was initiated as early as 1921, but it was only in 1966 that the Vector Control Unit (VCU) was established to additionally tackle dengue haemorrhagic fever (DHF) that was first documented in the 1960s. Centred on source reduction and public education, and based on research into the bionomics and ecology of the vectors, the programme successfully reduced the Aedes House Index (HI) from 48% in 1966 to <5% in the 1970s. Further enhancement of the programme, including through legislation, suppressed the Aedes HI to around 1% from the 1990s. The current programme is characterised by 4 key features: (i) proactive inter-epidemic surveillance and control that is stepped up during outbreaks; (ii) risk-based prevention and intervention strategies based on advanced data analytics; (iii) coordinated inter-sectoral cooperation between the public, private, and people sectors; and (iv) evidence-based adoption of new tools and strategies. Dengue seroprevalence and force of infection (FOI) among residents have substantially and continuously declined over the 5 decades. This is consistent with the observation that dengue incidence has been delayed to adulthood, with severity highest among the elderly. Paradoxically, the number of reported dengue cases and outbreaks has increased since the 1990s with record-breaking epidemics. We propose that Singapore's increased vulnerability to outbreaks is due to low levels of immunity in the population, constant introduction of new viral variants, expanding urban centres, and increasing human density. The growing magnitude of reported outbreaks could also be attributed to improved diagnostics and surveillance, which at least partially explains the discord between rising trend in cases and the continuous reduction in dengue seroprevalence. Changing global and local landscapes, including climate change, increasing urbanisation and global physical connectivity are expected to make dengue control even more challenging. The adoption of new vector surveillance and control tools, such as the Gravitrap and Wolbachia technology, is important to impede the growing threat of dengue and other Aedes-borne diseases.
本文总结了过去半个世纪以来新加坡在登革热流行病学、风险因素和预防方面的经验教训。在这半个世纪里，新加坡从一个拥有 190 万人口的城市发展成为一个拥有 560 万人口的高度城市化的全球化城市国家。新加坡地处热带气候，绿树成荫的城市环境为埃及伊蚊和白纹伊蚊（传播登革热的蚊子媒介）的滋生创造了理想条件。早在 1921 年，就启动了一项主要针对疟疾的病媒控制计划，但直到 1966 年，才成立了病媒控制股（VCU），以应对 20 世纪 60 年代首次记录的登革出血热（DHF）。该计划以减少病媒来源和开展公众教育为中心，以病媒生态学和生物学研究为基础，成功将埃及伊蚊指数（HI）从 1966 年的 48%降低到 20 世纪 70 年代的<5%。从 20 世纪 90 年代起，通过立法等进一步加强该计划，将埃及伊蚊指数（HI）降低到 1%左右。目前的计划有以下 4 个特点：（i）在疫情爆发期间加强的主动的疫情间监测和控制；（ii）基于先进数据分析的基于风险的预防和干预策略；（iii）公共、私营和民间部门之间的协调部门间合作；以及（iv）基于证据采用新工具和策略。在过去的 50 年里，居民的登革热血清流行率和感染率（FOI）大幅持续下降。这与登革热发病率推迟到成年期以及老年人发病率最高的观察结果一致。自 20 世纪 90 年代以来，报告的登革热病例和疫情数量增加，创历史新高，这似乎与这一情况相悖。我们认为，新加坡对疫情爆发的脆弱性增加是由于人群免疫力低下、新病毒变种的不断引入、城市中心不断扩大以及人口密度不断增加所致。报告的疫情数量不断增加，可能还归因于诊断和监测技术的提高，这至少部分解释了病例上升趋势与登革热血清流行率持续下降之间的不相符。不断变化的全球和地方景观，包括气候变化、城市化的不断发展和全球物质联系的加强，预计将使登革热控制更加具有挑战性。采用新的病媒监测和控制工具，如 Gravitrap 和沃尔巴克氏体技术，对于遏制登革热和其他由埃及伊蚊传播的疾病的日益严重的威胁非常重要。
