Evaluation of Vector-Enabled Xenosurveillance in Rural Guatemala

Abstract

Surveillance methods that permit rapid detection of circulating pathogens in low-resource settings are desperately needed. In this study, we evaluated a mosquito bloodmeal-based surveillance method ("xenosurveillance") in rural Guatemala. Twenty households from two villages (Los Encuentros and Chiquirines) in rural southwest Guatemala were enrolled and underwent weekly prospective surveillance from August 2019 to December 2019 (16 weeks). When febrile illness was reported in a household, recently blood-fed mosquitoes were collected from within dwellings and blood samples taken from each member of the household. Mosquitoes were identified to species and blood sources identified by sequencing. Shotgun metagenomic sequencing was used to identify circulating viruses. Culex pipiens (60.9%) and Aedes aegypti (18.6%) were the most abundant mosquitoes collected. Bloodmeal sources were most commonly human (32.6%) and chicken (31.6%), with various other mammal and avian hosts detected. Several mosquito-specific viruses were detected, including Culex orthophasma virus. Human pathogens were not detected. Therefore, xenosurveillance may require more intensive sampling to detect human pathogens in Guatemala and ecologically similar localities in Central America.

Figure 1.

Total and blood-fed mosquitoes collected increases over rainy season. Total mosquitoes collected per household during symptomatic episodes over the 16-week study (gray dashed line). Blood-fed mosquitoes collected per household (black solid line). Rainy season indicated by shaded background.

Figure 2.

Many bloodmeals obtained from avian species due to large numbers of Culex pipiens. The cytochrome oxidase 1 gene was amplified and sequenced to perform a BLAST search using the Barcode of Life database. A total of 343 of 488 (70.3%) species-identified mosquito samples were able to be traced to a single host source. (A) Percent of mosquito bloodmeals identified as mammal or avian host sources for each mosquito species. (B) Percent of all identified host sources Cx. pipiens mosquito bloodmeals. (C) Percent of all identified host sources of Ae. aegypti mosquito bloodmeals.

Figure 3.

Shotgun metagenomic sequencing reveals many insect-specific viruses but no human viruses. Extracted nucleic acid from DBS were pooled by volume according to household, collection time, and type (human or mosquito) in addition to water, FTA card, and HeLa cell controls. Shotgun metagenomic sequencing libraries were created and obtained sequencing reads were run through a taxonomic assessment pipeline as described. Viral reads were tallied by unique taxonomic ID. (A) Total number of reads obtained per n in sample for each library type. (B) Proportion of identified reads aligning at the super-kingdom level to viruses. (C) Virus read tallies (excluding phage) in mosquito libraries with a cutoff value of 30 hits.