La Crosse virus (LACV) causes the majority of pediatric arboviral encephalitis cases in the United States, with Ohio historically reporting the highest incidence of LACV neuroinvasive disease (LACV-ND). To identify county-level risk factors, we analyzed two decades (2003-2023) of Ohio surveillance data across all 88 counties using spatial statistical methods. Land-use correlation screening identified deciduous forest cover (ρ = 0.36, adjusted p = 0.006) and pasture/hay cover (ρ = 0.37, adjusted p = 0.004) as significant environmental correlates. However, Amish population share emerged as a substantially stronger predictor (ρ = 0.71, p << 0.001). Cases clustered in east-central Ohio, where Holmes County, home to the world's second-largest Amish settlement, exhibited the highest statewide incidence. We fit a Spatial Durbin Model to decompose within-county (direct) and spillover (indirect) effects while controlling for spatial autocorrelation. Amish population share remained the sole significant predictor after adjusting for land use and spatial structure, with total effects (β = 8.2) significantly larger than environmental variables (deciduous forest β = 0.3, pasture/hay β = -0.7). These findings indicate that Amish lifeways, potentially including occupational exposures, housing characteristics, or healthcare-seeking behaviors, represent critical but understudied LACV risk factors. Given the severe morbidity of pediatric LACV-ND and absence of vaccines, our results support targeted prevention efforts in Ohio Amish communities, contingent on culturally appropriate intervention strategies.
Chaney et al. (Fri,) studied this question.