Risk of exposure to eastern equine encephalomyelitis virus increases with the density of northern cardinals.
Authors: Estep Laura K, McClure Christopher J W, Vander Kelen Patrick, Burkett-Cadena Nathan D, Sickerman Stephen, Hernandez José, Jinright Joseph, Hunt Brenda, Lusk John, Hoover Victor, Armstrong Keith, Stark Lillian M, Hill Geoffrey E, Unnasch Thomas R
Journal: PloS one
Summary
# Eastern Equine Encephalomyelitis and Cardinal Populations: A Vector Preference Story Understanding disease transmission often requires examining ecological complexity, yet a counterintuitive principle has dominated recent thinking: that diverse host communities actually reduce pathogen risk by offering "dead-end" hosts that interrupt transmission cycles. This study challenged that assumption by investigating eastern equine encephalomyelitis virus (EEEV) transmission in Florida, hypothesising that mosquito vector preferences might override any protective effect of biodiversity. Researchers modelled exposure risk to sentinel chickens across Walton County between 2009 and 2010, testing whether avian species richness or densities of individual species predicted EEEV transmission better, and found that northern cardinal density emerged as the strongest predictor alongside *Culiseta melanura* mosquito abundance—not overall bird diversity. Because northern cardinals are highly preferred bloodmeal hosts for EEEV vectors, their local abundance directly correlates with virus transmission risk regardless of how many other bird species inhabit the area. For equine professionals managing horses in EEEV-endemic regions, this finding underscores that monitoring specific host species ecology—particularly native cardinals—may be more informative for disease risk assessment than broad biodiversity measures, and that vector control efforts should account for which bird species are actively amplifying infections in particular localities.
Read the full abstract on PubMed
Practical Takeaways
- •Properties with high northern cardinal populations may present elevated EEEV risk to horses; consider this in regional risk assessments and vaccination strategies
- •Ecological factors (specific host densities and vector preferences) rather than general biodiversity determine mosquito-borne disease transmission risk
- •Monitor local bird populations as a practical indicator of vector-borne disease pressure in your area
Key Findings
- •Northern cardinal density was the strongest predictor of EEEV exposure risk to sentinel chickens in Walton County, Florida (2009-2010)
- •Culiseta melanura mosquito abundance was included in the highest-ranking predictive model alongside cardinal density
- •Mosquito vector host preferences violate assumptions of dilution effect theory, making pathogen transmission dependent on preferred host availability rather than overall host species richness