Development and Field Evaluation of a System to Collect Mosquito Excreta for the Detection of Arboviruses

Abstract

Mosquito-borne diseases are a major public health concern globally and early detection of pathogens is critical to implement vector management and control strategies. Existing methods for pathogen detection include screening sentinel animals for antibodies and analyzing mosquitoes for pathogen presence. While these methods are effective, they are also expensive, labor-intense, and logistically challenging. To address these limitations, a new method was developed whereby mosquito saliva is collected on honey-coated nucleic acid preservation cards which are analyzed by molecular assays for detection of pathogens. However, mosquitoes only expel small amounts of saliva when feeding on these cards, potentially leading to false negatives. Another bodily fluid that is expelled by mosquitoes in larger volumes than saliva is excreta, and recent laboratory experiments have demonstrated that a range of mosquito-borne pathogens can be detected in mosquito excreta. In the current study, we have modified light and passive mosquito traps to collect their excreta and assessed their efficacy in field evaluations. From these field-collections, we detected West Nile, Ross River, and Murray Valley encephalitis viruses. Our findings suggest that mosquito traps are easily modified to collect excreta and, that this system has the potential to enhance detection of pathogens.

Arbovirus surveillance using FTATMcards in modified CO2‐baited encephalitis virus surveillance traps in the Northern Territory, Australia

“…However, since this study was conducted, Ramirez et al () have found that detection of arboviruses in excreta under laboratory conditions was more sensitive compared to detection in saliva, and that excreta samples tested positive to arbovirus RNA within a much shorter time period following the ingestion of an infectious blood meal compared to mosquito saliva samples, where the intrinsic virus incubation period delayed rapid virus RNA detection. Using mosquito excreta for arbovirus detection has since been successfully tested in the field by Meyer et al (), with this method another potential alternative for rapid arbovirus detection.…”

Metagenomic Analysis of the Virome of Mosquito Excreta

“…To determine if viral genomes could be sequenced from excreta sampled from mosquitoes collected using the methods of Meyer et al ( 16 ), studies were conducted in Far North Queensland (FNQ) and South East Queensland (SEQ) in March and April 2018 ( Fig. S1 ).…”

“…Additionally, based on results obtained from sequencing mosquito excreta, virus detection and subsequent isolation could be attempted from the mosquito homogenates for viruses that can be grown in vitro . Use of traps that are highly selective for mosquitoes, such as CO 2 -baited passive box traps that do not deploy lights that attract other insects, is recommended ( 16 , 41 ).…”

“…S1 ). Adult mosquitoes were collected using Centers for Disease Control and Prevention (CDC) model 512 light traps (John W. Hock Company, Gainesville, FL) fitted with collection containers modified from the design described in reference 16 . Collection containers housed two filter paper cards soaked with blue-dyed honey and a removable polycarbonate substrate for excreta collection.…”

“…Additionally, hepatitis B virus, which does not replicate in the mosquito, has been detected in mosquito excreta by RT-PCR and Southern blotting up to 72 h after the ingestion of an infectious blood meal ( 15 ). A system to collect mosquito excreta in the field for the detection of circulating arboviruses has been developed, with mosquito excreta samples having been found to be positive for WNV, RRV, and Murray Valley encephalitis virus (MVEV) in Australia ( 16 ).…”