Tracking SARS-CoV-2 seropositivity in rural communities using blood-fed mosquitoes: a proof-of-concept study

Area of Science:

• Epidemiology
• Immunology
• Vector-borne disease research

Background:

• Effective disease surveillance for SARS-CoV-2 is limited in regions lacking robust infrastructure.
• Asymptomatic and pauci-symptomatic infections in young populations complicate SARS-CoV-2 detection.
• Traditional sero-surveillance methods are often resource-intensive and challenging in settings like Mali.

Purpose of the Study:

• To evaluate the feasibility of using blood-fed mosquitoes as a non-invasive method for SARS-CoV-2 sero-surveillance.
• To assess the reliability of detecting human anti-SARS-CoV-2 antibodies in mosquito bloodmeals.
• To determine the cost-effectiveness and scalability of this novel surveillance approach.

Main Methods:

• Collection of naturally blood-fed mosquitoes from laboratory and field sites in Mali.
• Laboratory analysis of mosquito bloodmeals for immunoglobulin-G (IgG) antibodies against SARS-CoV-2 antigens using bead-based immunoassay.
• Comparison of sero-positivity rates with existing venous blood-based surveillance data.

Main Results:

• High sensitivity (0.92) and specificity (0.98) in detecting SARS-CoV-2 antibodies in mosquito bloodmeals up to 10 hours post-feeding.
• Detection of rising SARS-CoV-2 antibody reactivity correlating with pandemic progression.
• Crude sero-positivity rates increased from 6.3% (Oct-Nov 2020) to 25.1% (Feb 2021), with one urban site reaching 46.7%.

Conclusions:

• Blood-fed mosquitoes serve as viable, non-invasive samples for large-scale human disease sero-surveillance.
• This method is cost-effective and informative, particularly in resource-limited areas with high mosquito populations.
• Mosquito bloodmeal analysis offers a scalable solution for monitoring both vector-borne and non-vector-borne infectious diseases.