Spatiotemporal Environmental Drivers of Eastern Equine Encephalitis Virus in Central Florida: Towards a Predictive Model for a Lethal Disease

Abstract

Eastern equine encephalitis virus (EEEV) is a mosquito-borne virus that affects humans and horses, with a high case fatality rate in both species. The virus can be transmitted by several mosquito species and maintained in multiple reservoir hosts, making EEEV dynamics difficult to anticipate. In this study, we identified spatial and temporal factors that precede EEEV detection using sentinel chicken surveillance data from Orange County, Florida, from 2003 to 2017. We first examined the land cover and mosquito species composition associated with sentinel chicken sites. We then fit distributed lag nonlinear models of EEEV detection at the county scale, using monthly temperature, precipitation, and Southern Oscillation Index values, and at the sentinel flock-scale, using remotely sensed temperature and wetness indicators. We found positive associations between the percent wooded wetlands and the count of EEEV detections. We found Culiseta melanura (Diptera: Culicidae) were more abundant at positive sites in winter and summer, but Coquillettidia perturbans (Walker) were more abundant at positive sites in spring. In the county-wide model, precipitation, temperature, and Southern Oscillation Index values at lags of two, nine, and twelve months were significant, respectively, while temperature and wetness were significant at lags of eight and six months in the flock-specific models.

The Role of Urban-to-Rural Gradients in Mosquito-Borne Disease Risk in Ontario, Canada

“…In addition to the effect of urban landscapes, I found that forested land cover was positively associated with EEEV seroprevalence in Song Sparrows, and negatively associated with WNV seroprevalence. For EEEV virus, this is consistent with the importance of forested wetland areas to the main vectors of EEEV, notably Culiseta melanura (167)(168)(169)(170). In Eastern Ontario, Culex pipiens/restuans mosquitoes are less prevalent in forests (171), which explains my observation that WNV seroprevalence in Song Sparrows was lower in forested land covers.…”

“…For EEEV however, studies investigating a relationship between human landscapes and disease risk are scarce. This is likely a consequence of an established relationship between EEEV prevalence, its primary mosquito vector Culiseta melanura (59), and forested wetland habitats (167)(168)(169)(170). However, mosquitoes involved in EEEV transmission, most notably Culiseta melanura, are still found in urban and agroecosystems (171) that may include patches of forest and wetlands used by these mosquitoes (172,173).…”

Dynamics of eastern equine encephalitis virus during the 2019 outbreak in the Northeast United States

“…melanura has also been found to occasionally feed on mammals in the Northeast (Molaei et al, 2006). In terms of viral dynamics, previous work demonstrated that EEEV circulates year round in Florida and is introduced into the Northeast through seasonal bird migration (Mundis et al, 2022;Tan et al, 2018), although this process does not happen predictably every year. Predicting the annual case dynamics is therefore difficult, having to take into account viral dynamics across multiple species and geographic scales.…”