Abstract
BackgroundDengue viruses (DENV) can be transmitted from an adult female Aedes aegypti mosquito through the germ line to the progeny; however, there is uncertainty if this occurs at a frequency that is epidemiologically significant. We measured vertical transmission of DENV from field-reared Ae. aegypti to their F1 progeny after feeding upon blood from dengue patients. We also examined the transmission potential of F1 females.MethodsWe examined the frequency of vertical transmission in field-reared mosquitoes, who fed upon blood from acutely viremic dengue patients, and the capacity for vertically infected females to subsequently transmit virus horizontally, in two sets of experiments: (i) compared vertical transmission frequency of field-reared Ae. aegypti and Ae. albopictus, in individual progeny; and (ii) in pooled progeny derived from field- and laboratory-reared Ae. aegypti.ResultsOf 41 DENV-infected and isofemaled females who laid eggs, only a single female (2.43%) transmitted virus to one of the F1 progeny, but this F1 female did not have detectable virus in the saliva when 14 days-old. We complemented this initial study by testing for vertical transmission in another 460 field-reared females and > 900 laboratory-reared counterparts but failed to provide any further evidence of vertical virus transmission.ConclusionsIn summary, these results using field-reared mosquitoes and viremic blood from dengue cases suggest that vertical transmission is uncommon. Field-based studies that build on these observations are needed to better define the contribution of vertical DENV transmission to dengue epidemiology.
Highlights
Dengue viruses (DENV) can be transmitted from an adult female Aedes aegypti mosquito through the germ line to the progeny; there is uncertainty if this occurs at a frequency that is epidemiologically significant
Patient cohorts and healthy volunteers Forty patient participants were enrolled between November 2018 and September 2019, with written informed consent obtained by qualified staff from Hospital for Tropical Diseases (HTD)
Ten patient blood samples were excluded from the study because they were DENV-negative when tested by reverse transcriptase polymerase chain reaction (RT-PCR)
Summary
Dengue viruses (DENV) can be transmitted from an adult female Aedes aegypti mosquito through the germ line to the progeny; there is uncertainty if this occurs at a frequency that is epidemiologically significant. Dengue is caused by one of four dengue virus (DENV) serotypes, which are transmitted primarily by Aedes aegypti and Ae. albopictus mosquitoes [3]. In recent years, both species have expanded their geographical distribution and, predictions of various climate change scenarios suggest their distribution will increase further. Both species have expanded their geographical distribution and, predictions of various climate change scenarios suggest their distribution will increase further Such scenarios are likely to trigger emergence and reemergence of arboviruses such as dengue worldwide [4].
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