A Bayesian spatio-temporal model for forecasting the prevalence of antibodies to Borrelia burgdorferi, causative agent of Lyme disease, in domestic dogs within the contiguous United States

Abstract

This paper models the prevalence of antibodies to Borrelia burgdorferi in domestic dogs in the United States using climate, geographic, and societal factors. We then use this model to forecast the prevalence of antibodies to B. burgdorferi in dogs for 2016. The data available for this study consists of 11,937,925 B. burgdorferi serologic test results collected at the county level within the 48 contiguous United States from 2011-2015. Using the serologic data, a baseline B. burgdorferi antibody prevalence map was constructed through the use of spatial smoothing techniques after temporal aggregation; i.e., head-banging and Kriging. In addition, several covariates purported to be associated with B. burgdorferi prevalence were collected on the same spatio-temporal granularity, and include forestation, elevation, water coverage, temperature, relative humidity, precipitation, population density, and median household income. A Bayesian spatio-temporal conditional autoregressive (CAR) model was used to analyze these data, for the purposes of identifying significant risk factors and for constructing disease forecasts. The fidelity of the forecasting technique was assessed using historical data, and a Lyme disease forecast for dogs in 2016 was constructed. The correlation between the county level model and baseline B. burgdorferi antibody prevalence estimates from 2011 to 2015 is 0.894, illustrating that the Bayesian spatio-temporal CAR model provides a good fit to these data. The fidelity of the forecasting technique was assessed in the usual fashion; i.e., the 2011-2014 data was used to forecast the 2015 county level prevalence, with comparisons between observed and predicted being made. The weighted (to acknowledge sample size) correlation between 2015 county level observed prevalence and 2015 forecasted prevalence is 0.978. A forecast for the prevalence of B. burgdorferi antibodies in domestic dogs in 2016 is also provided. The forecast presented from this model can be used to alert veterinarians in areas likely to see above average B. burgdorferi antibody prevalence in dogs in the upcoming year. In addition, because dogs and humans can be exposed to ticks in similar habitats, these data may ultimately prove useful in predicting areas where human Lyme disease risk may emerge.

Borrelia burgdorferiInfection and Lyme Disease in North American Horses: A Consensus Statement

“…The seroprevalence of B. burgdorferi in dogs, horses and humans is increasing nationwide, as is the range of the Ixodid tick . Data strongly support the regional spread of Ixodes ticks, and animal and human exposure to B. burgdorferi in the Midwest, Pacific, and East Coasts of the United States.…”

“…Based on 66,582 samples submitted to the Vector Borne Disease Lab at North Carolina State University, data supports a temporal increase in B. burgdorferi infection in dogs in the southern United States between 2008 and 2010 . A baseline B. burgdorferi antibody prevalence map (Fig ) for dogs has been developed by a Bayesian spatio‐temporal model . It might be expected that horses would have a similar or even higher seroprevalence than dogs in the same geographic areas because horses often have equal or greater exposure to tick habitat and are less likely to have tick preventative control treatments.…”

“…The seroprevalence of B. burgdorferi in dogs, horses and humans is increasing nationwide, as is the range of the Ixodid tick. 30,[44][45][46][47][48][49] Data strongly support the regional spread of Ixodes ticks, and animal and human exposure to B. burgdorferi in the Midwest, Pacific, and East Coasts of the United States. A recent review of 6 different literature searches, documented an increased incidence and prevalence of Ixodes scapularis and I. pacificus in the United States within the last 20 years (Fig 1).…”

“…54 A baseline B. burgdorferi antibody prevalence map ( Fig 2) for dogs has been developed by a Bayesian spatio-temporal model. 45 It might be expected that horses would have a similar or even higher seroprevalence than dogs in the same geographic areas 55 because horses often have equal or greater exposure to tick habitat and are less likely to have tick preventative control treatments.…”

“…Observed Borrelia burgdorferi antibody prevalence in domestic dogs for 2015 45. From Stella C. Watson et al PLoS One 2017 with permission.…”