Multi-season transmission model of Eastern Equine Encephalitis.
Authors: Petrucciani Alexa, Yu Geonsik, Ventresca Mario
Journal: PloS one
Summary
# Eastern Equine Encephalitis: Understanding Transmission Dynamics in a Changing Landscape Recent decades have witnessed an unexplained surge in Eastern Equine Encephalitis cases despite the disease's recognition since the 1930s, prompting urgent investigation into the mechanisms driving this resurgence. Petrucciani and colleagues developed deterministic and stochastic transmission models parameterised using 16 years of sentinel chicken seroconversion data from Florida to disentangle the roles of enzootic vectors (particularly *Culiseta melanura*) and bridge vectors in perpetuating EEE circulation and spillover to dead-end hosts. The analysis revealed a critical asymmetry: whilst changes in enzootic vector transmission substantially increased avian infection rates, a mere 5% shift in bridge vector host-feeding preference—the propensity to feed on birds versus other animals—increased human infections more than 20-fold, suggesting this ecological parameter acts as a regulatory "valve" controlling disease spillover. The modelling framework explored plausible drivers of recent case increases, including viral mutations enhancing infectivity, altered vertical transmission patterns, and shifts in mosquito feeding behaviour, indicating that climate-driven or behavioural changes in bridge vector ecology may represent a more critical intervention point than enzootic cycle modifications. For equine practitioners, these findings highlight that surveillance of local mosquito populations and their feeding preferences may offer more predictive value for human and equine risk assessment than metrics focused solely on avian seroprevalence.
Read the full abstract on PubMed
Practical Takeaways
- •Monitor mosquito vector populations and feeding behavior patterns in your region, as small shifts in bridge vector host preference can dramatically increase disease risk to horses and humans
- •EEE risk is driven by complex ecological interactions between multiple mosquito species; local public health and biosecurity efforts should focus on controlling bridge vectors that feed on both birds and horses
- •Recent EEE case increases may reflect environmental or behavioral changes in mosquito populations rather than viral changes alone; adaptive management strategies should consider seasonal transmission cycles and regional vector ecology
Key Findings
- •Enzootic mosquitoes (Culiseta melanura) are critical for EEE persistence in bird populations, while bridge vectors drive human disease transmission
- •A 5% change in bridge vector bird-feeding preference can increase dead-end host infections by over 20-fold, acting as a regulatory valve for disease spillover
- •Changes in enzootic vector transmission increase avian cases more drastically than equivalent bridge vector changes, but bridge vector behavior controls spillover to humans and horses
- •Multi-season deterministic and stochastic models using 16 years of sentinel chicken seroconversion data reveal climate and host behavior changes as potential drivers of recent EEE case increases