Improving vector-borne pathogen surveillance: A laboratory-based study exploring the potential to detect dengue virus and malaria parasites in mosquito saliva
Vanessa R Melanson1, Ryan Jochim2, Michael Yarnell3, Karen Bingham Ferlez4, Soumya Shashikumar5, Jason H Richardson6
1 Molecular and Translational Science Division, United States Army Research Institute of Infectious Diseases, Fort Detrick, Maryland, USA
2 Veterinary Diagnostic Technology, Inc., Wheat Ridge, Colorado, USA
3 University of Colorado Denver-Anschutz Medical Campus, Division of Pulmonary Sciences and Critical Care Medicine, Aurora, Colorado, USA
4 Janssen R&D, Malvern, Pennsylvania, USA
5 Infectious Diseases Department, Naval Military Malaria Vaccine Research Program, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
6 IVCC, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
Vanessa R Melanson
Molecular and Translational Science Division, United States Army Research Institute of Infectious Diseases, 1425 Porter Street, Fort Detrick, MD 21702
Source of Support: None, Conflict of Interest: None
Background & objectives: Vector-borne pathogen surveillance programmes typically rely on the collection of large numbers of potential vectors followed by screening protocols focused on detecting pathogens in the arthropods. These processes are laborious, time consuming, expensive, and require screening of large numbers of samples. To streamline the surveillance process, increase sample throughput, and improve cost-effectiveness, a method to detect dengue virus and malaria parasites (Plasmodium falciparum) by leveraging the sugar-feeding behaviour of mosquitoes and their habit of expectorating infectious agents in their saliva during feeding was investigated in this study.
Methods: Dengue virus 2 (DENV-2) infected female Aedes aegypti mosquitoes and P. falciparum infected female Anopheles stephensi mosquitoes were allowed to feed on honey coated Flinders Technical Associates —FTA® cards dyed with blue food colouring. The feeding resulted in deposition of saliva containing either DENV-2 particles or P. falciparum sporozoites onto the FTA card. Nucleic acid was extracted from each card and the appropriate real-time PCR (qPCR) assay was run to detect the pathogen of interest.
Results: As little as one plaque forming unit (PFU) of DENV-2 and as few as 60 P. falciparum parasites deposited on FTA cards from infected mosquitoes were detected via qPCR. Hence, their use to collect mosquito saliva for pathogen detection is a relevant technique for vector surveillance.
Interpretation & conclusion: This study provides laboratory confirmation that FTA cards can be used to capture and stabilize expectorated DENV-2 particles and P. falciparum sporozoites from infectious, sugar-feeding mosquitoes in very low numbers. Thus, the FTA card-based mosquito saliva capture method offers promise to overcome current limitations and revolutionize traditional mosquito-based pathogen surveillance programmes. Field testing and further method development are required to optimize this strategy.