Vector-Host Interactions of Culiseta melanura in a Focus of Eastern Equine Encephalitis Virus Activity in Southeastern Virginia.
Authors: Molaei Goudarz, Armstrong Philip M, Abadam Charles F, Akaratovic Karen I, Kiser Jay P, Andreadis Theodore G
Journal: PloS one
Summary
# Eastern Equine Encephalitis: Understanding Mosquito-Host Interactions in Virginia Culiseta melanura mosquitoes are the principal vectors of Eastern equine encephalitis virus (EEEV) in eastern North America, yet their feeding preferences and role in virus transmission had not been thoroughly characterised in mid-Atlantic regions where equine outbreaks occur. Researchers collected nearly 200 engorged mosquitoes from 55 sites across Suffolk, Virginia during the 2013 transmission season and identified blood meal sources through mitochondrial DNA sequencing; simultaneously, they screened field-caught mosquitoes for active EEEV infection using multiple detection methods including cell culture and PCR. Blood meal analysis revealed that 95.2% of feeds were taken from birds, with American Robins accounting for 42.6% of all avian meals, followed by Northern Cardinals (16.0%) and European Starlings (11.2%)—all recognised as EEEV-competent species—whilst just 4.3% of blood meals came from mammals; EEEV infection peaked in late July with a maximum likelihood infection rate of 4.46 per 1,000 mosquitoes across 106 positive pools. The critical finding that Cs. melanura predominantly feeds on avian hosts confirms the mosquito's role in maintaining enzootic cycles amongst bird populations, but the small yet consistent proportion of mammalian blood meals (4.3%) indicates occasional spillover risk to horses and humans during high transmission periods. For equine professionals, these data reinforce the importance of peak-season (late July onwards) vector control measures, protective strategies for at-risk animals in endemic areas, and heightened clinical vigilance when EEEV activity is documented in local mosquito populations.
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Practical Takeaways
- •Eastern equine encephalitis risk is highest in late July; implement vector control and vaccination protocols during this peak transmission window
- •Properties with abundant American Robins and Northern Cardinals pose higher EEEV transmission risk as these bird species sustain the enzootic cycle
- •Although rare, mammalian feeding by Culiseta melanura indicates horses can be infected; maintain appropriate biosecurity and mosquito management during outbreak seasons
Key Findings
- •Culiseta melanura obtained blood meals from avian hosts in 95.2% of cases, with American Robin (42.6%) and Northern Cardinal (16.0%) being primary hosts
- •EEEV was detected in 106 mosquito pools with peak virus activity in late July 2013 at an infection rate of 4.46 per 1,000 mosquitoes
- •Only 4.3% of blood meals came from mammalian hosts, suggesting limited but potential epidemic transmission to horses and humans