Disease & Vector Studies I
Disease & Vector Studies I
Accurate, rapid, and cost-effective surveillance of arbovirus mosquito vectors is critical for monitoring species distribution and infection prevalence and ultimately mitigating transmission risk. Currently, vector surveys conducted by the Southern Nevada Health District (SNHD) are limited to a few productive sentinel sites, with considerable infrastructure and logistical requirements. New vector surveillance methods that are simple and unbiased at the sampling stage are needed. One potential method to increase efficient vector sampling capacity may be to exploit detection of environmental DNA (eDNA), shed by vectors breeding in aquatic environments.
In this study, we first designed and optimized a novel multiplex TaqMan quantitative PCR (qPCR) assay, based on single nucleotide polymorphisms in cytochrome oxidase I, for simultaneous detection of the three major regionally important arbovirus vector species: Culex (Cx.) quinquefasciatus, Cx. tarsalis, and Aedes (Ae.) aegypti. Next, 50ml water samples were collected from across Clark County using sterile plastic syringes and were filtered through 0.22µm sterile polyether sulfone syringe filters. Collection sites included water bodies that were adjacent to overnight gravid traps and BG sentinel traps, set by the SNHD, to compare vector species composition between sampling methods and additional aquatic environments in local public parks, golf courses, and drainage ditches. eDNA was extracted from filter membranes and screened for vector species presence using our qPCR assay. eDNA deposited by co-occupying Cx. quinquefasciatus and Ae. aegypti was detected in water samples, without observable larvae breeding, from multiple drainage ditches. Cx. tarsalis was identified in water samples from stormwater runoff and drainage channels in a public park.
eDNA surveillance has the potential to be implemented as a field-friendly, arbovirus vector surveillance tool for expanded entomological monitoring capacity in southern Nevada, to detect changes in dispersal patterns of arbovirus vector species as well as the spread of new invasive vector species.