Environmental Health Institute, National Environment Agency, Singapore, Singapore.
PLoS Negl Trop Dis. 2012;6(8):e1792. doi: 10.1371/journal.pntd.0001792. Epub 2012 Aug 28.
Zika virus (ZIKV) is a little known flavivirus that caused a major outbreak in 2007, in the South-western Pacific Island of Yap. It causes dengue-like syndromes but with milder symptoms. In Africa, where it was first isolated, ZIKV is mainly transmitted by sylvatic Aedes mosquitoes. The virus has also been isolated from Ae. aegypti and it is considered to be the vector involved in the urban transmission of the virus. Transmission of the virus by an African strain of Ae. aegypti has also been demonstrated under laboratory conditions. The aim of the present study is to describe the oral susceptibility of a Singapore strain of Ae. aegypti to ZIKV, under conditions that simulate local climate.
METHODOLOGY/PRINCIPAL FINDINGS: To assess the receptivity of Singapore's Ae. aegypti to the virus, we orally exposed a local mosquito strain to a Ugandan strain of ZIKV. Upon exposure, fully engorged mosquitoes were maintained in an environmental chamber set at 29 °C and 70-75% RH. Eight mosquitoes were then sampled daily from day 1 to day 7, and subsequently on days 10 and 14 post exposure (pe). The virus titer of the midgut and salivary glands of each mosquito were determined using a tissue culture infectious dose(50) (TCID(50)) assay. High midgut infection and salivary gland dissemination rates were observed. By day 5 after the infectious blood meal, ZIKV was found in the salivary glands of more than half of the mosquitoes tested (62%); and by day 10, all mosquitoes were potentially infective.
CONCLUSIONS/SIGNIFICANCE: This study showed that Singapore's urban Ae. aegypti are susceptible and are potentially capable of transmitting ZIKV. The virus could be established in Singapore should it be introduced. Nevertheless, Singapore's current dengue control strategy is applicable to control ZIKV.
寨卡病毒（ZIKV）是一种鲜为人知的黄病毒，曾于 2007 年在西南太平洋的雅浦岛引发大规模疫情。它会引起类似登革热的综合征，但症状较轻。在该病毒首次被分离的非洲，ZIKV 主要通过丛林型埃及伊蚊传播。该病毒也已从埃及伊蚊中分离出来，被认为是该病毒在城市传播中涉及的媒介。实验室条件下也已证明，非洲株埃及伊蚊可传播该病毒。本研究旨在描述在模拟当地气候条件下，新加坡埃及伊蚊对 ZIKV 的口服易感性。
方法/主要发现：为评估新加坡埃及伊蚊对该病毒的易感性，我们用乌干达株 ZIKV 对当地蚊虫进行了经口感染。感染后，将完全饱血的蚊子保存在环境室中，温度设定为 29°C，相对湿度为 70-75%。然后，从感染后第 1 天至第 7 天，每天从 8 只蚊子中取样，随后在感染后第 10 天和第 14 天（pe）取样。使用组织培养感染剂量（50）（TCID（50））测定法，检测每只蚊子中中肠和唾液腺的病毒滴度。观察到高的中肠感染和唾液腺传播率。在感染性血液餐后第 5 天，超过一半的测试蚊子（62%）中发现了 ZIKV；到第 10 天，所有蚊子都具有潜在的感染性。
结论/意义：本研究表明，新加坡的城市埃及伊蚊易受感染，并且具有传播 ZIKV 的潜在能力。如果引入该病毒，它可能会在新加坡建立。不过，新加坡目前的登革热控制策略适用于控制 ZIKV。
