Surendran S N, Veluppillai T, Eswaramohan T, Sivabalakrishnan K, Noordeen F, Ramasamy R
Department of Zoology, Faculty of Science, University of Jaffna, Sri Lanka.
Department of Microbiology, Faculty of Medicine, University of Peradeniya, Sri Lanka.
J Vector Borne Dis. 2018 Jan-Mar;55(1):26-33. doi: 10.4103/0972-9062.234623.
BACKGROUND & OBJECTIVES: Aedes aegypti and Ae. albopictus are major arboviral vectors that are considered to lay eggs, and undergo preimaginal development only in fresh water collections. However, recently they have been also shown to develop in coastal brackish water habitats. The ability of the biologically variant salinity-tolerant Aedes vectors to transmit arboviral diseases is unknown. We therefore, investigated the infection of salinity-tolerant Aedes mosquitoes with dengue virus (DENV) and analysed dengue incidence and rainfall data to assess the contribution of salinity-tolerant Aedes vectors to dengue transmission in the coastal Jaffna peninsula in Sri Lanka.
Brackish and fresh water developing female Ae. aegypti and Ae. albopictus were tested for their ability to become infected with DENV through in vitro blood feeding and then transmit DENV vertically to their progeny. An immunochromatographic test for the NS1 antigen was used to detect DENV. Temporal variation in dengue incidence in relation to rainfall was analysed for the peninsula and other parts of Sri Lanka.
Aedes aegypti and Ae. albopictus developing in brackish water, became infected with DENV through in vitro blood feeding and the infected mosquitoes were able to vertically transmit DENV to their progeny. Monsoonal rainfall was the discernible factor responsible for the seasonal increase in dengue incidence in the peninsula and elsewhere in Sri Lanka.
INTERPRETATION & CONCLUSION: Fresh water Aedes vectors are main contributors to the increased dengue incidence that typically follows monsoons in the Jaffna peninsula and elsewhere in Sri Lanka. It is possible however, that brackish water-developing Aedes constitute a perennial reservoir for DENV to maintain a basal level of dengue transmission in coastal areas of the peninsula during the dry season, and this supports increased transmission when monsoonal rains expand populations of fresh water Aedes.
埃及伊蚊和白纹伊蚊是主要的虫媒病毒传播媒介，一般认为它们只在淡水积水处产卵并经历幼期发育。然而，最近研究表明它们也能在沿海咸淡水生境中发育。具有生物学差异的耐盐伊蚊传播虫媒病毒疾病的能力尚不清楚。因此，我们调查了耐盐伊蚊感染登革病毒（DENV）的情况，并分析了登革热发病率和降雨数据，以评估耐盐伊蚊在斯里兰卡贾夫纳半岛沿海地区登革热传播中的作用。
对在咸淡水和淡水中发育的雌性埃及伊蚊和白纹伊蚊进行体外吸血感染DENV的能力测试，然后检测其是否能将DENV垂直传播给后代。采用NS1抗原免疫层析试验检测DENV。分析了该半岛及斯里兰卡其他地区登革热发病率随降雨的时间变化情况。
在咸淡水中发育的埃及伊蚊和白纹伊蚊通过体外吸血感染了DENV，且受感染的蚊子能够将DENV垂直传播给后代。季风降雨是该半岛及斯里兰卡其他地区登革热发病率季节性增加的明显因素。
淡水伊蚊是贾夫纳半岛及斯里兰卡其他地区季风后登革热发病率增加的主要原因。然而，在旱季，咸淡水发育的伊蚊有可能构成DENV的常年储存宿主，以维持半岛沿海地区登革热的基础传播水平，而当季风雨使淡水伊蚊数量增加时，这有助于增加登革热传播。
