Arboviral Surveillance Maps

With the introduction of West Nile (WN) virus to Florida in 2001, surveillance of arboviral activity has taken on added urgency. Eastern Equine Encephalitis (EEE) and St. Louis Encephalitis (SLE) viruses have been monitored by county mosquito control agencies and the Florida Department of Health (DOH) with sentinel chickens since 1978. West Nile virus was added to the surveillance program in 2001. Increased arboviral transmission to sentinel chickens can indicate an increased risk of arboviral transmission to humans. Timely analysis and interpretation of sentinel chicken surveillance results are imperative for an effective response to prevent arboviral transmission to humans. The spatial and temporal (spatiotemporal) attributes of each arbovirus are different and must be monitored closely. Traditional sentinel flock arboviral surveillance tools include tabular data reports and county-level based maps, which tend to give an exaggerated or underrated spatial view and a very limited temporal view of the arboviral activity. Better local, regional and statewide tools for sentinel flock arboviral surveillance must be developed for real-time use in risk analysis and arboviral activity response planning. Spatial analysis provided by a Geographic Information System (GIS) and temporal analysis using animation can bring surveillance results “to life” and help decision makers better see the real-time regional spatiotemporal attributes of arboviral activity in Florida.

The spatiotemporal aspects of arboviral transmission to sentinel chicken surveillance flocks is more easily interpreted and understood when visualized using an animation video than through traditional graphical and tabular data analysis. The animation video produces a smoother transition of arboviral activity through space and time than was previously possible using county-level paper maps and graphs, allowing viewers to better understand the ecology of each arbovirus. Spatially, EEE tends to be confined to northern Florida, while WN is found from the panhandle to Miami. Temporally, WN is present throughout the year and is spatially more abundant during the summer months, whereas EEE is more frequently reported during the spring and fall months. In addition, the animation video provides a much more efficient manner of segregating seasonal arboviral activity.

Mosquito control agencies’ response mechanisms must be fine-tuned to the spatial and temporal aspects of the individual arbovirus (WN, EEE, or SLE) if they are to respond appropriately. Detection of WN early in the year may not warrant the same response as detection of EEE at the same spatiotemporal location. Some agencies may wish to act based upon spatiotemporal arboviral activity in surrounding counties visualized in the animation video. Other agencies may not respond to activity within their own county, based upon the spatiotemporal aspects of that activity, such as late year EEE activity. The purpose of the animation video is to convey to mosquito control agencies and health departments throughout Florida that the most efficient use of the data generated in the sentinel surveillance programs, is real-time spatiotemporal analysis of surveillance data.