Member Research and Reports

Member Research and Reports

Kentucky: Geographical Clusters and Predictors of Rabies

The rabies virus causes progressive encephalomyelitis that is fatal in nearly 100 percent of untreated cases. In the United States, prevention, surveillance, and control costs for rabies are high, with wildlife acting as the primary reservoir for the disease.

[Photos: Dr. Steven R. Browning (left) and Dr. W. Jay Christian (right)]

In a new paper by a group of epidemiologists from the University of Kentucky, researchers report on their investigation of the current distribution of wildlife rabies in three southeastern states, with particular focus on raccoons as the primary eastern reservoir. They also identify demographic and geographic factors which may affect the risk of human exposure. The paper authors are: Ms. Sara Reilly of the Virginia Department of Public Health, an MPH graduate of the UK College of Public Health, with Dr. Wayne Sanderson, Dr. W. Jay Christian, and Dr. Steven R. Browning, all of the UK College of Public Health department of epidemiology. The paper appears in Vector-Borne and Zoonotic Diseases.


[Photos: Ms. Sara Reilly (left) and Dr. Wayne Sanderson (right)]

The ecologic study obtained county-level rabies surveillance data from state health departments and the United States Department of Agriculture Wildlife services for North Carolina, Virginia, and West Virginia from 2010 to 2013. A spatial statistical analysis was performed to identify county clusters with high or low rates of raccoon rabies in the three states. Potential demographic and geographic factors associated with these varying rates of rabies were assessed using a multivariable negative binomial regression model.

In North Carolina, raccoons constituted 50 percent of positive tests, in Virginia, 49 percent, and in West Virginia, 50 percent. Compared to persons residing in West Virginia counties, persons in North Carolina counties had 1.67 times the risk of exposure ( p < 0.0001) to a rabid raccoon and those in Virginia counties had 1.82 times the risk of exposure ( p < 0.0001) to a rabid raccoon. Compared to those counties where farmland makes up less than 17 percent of the total area, persons residing in counties with 17–28 percent farmland had a 32 percent increased risk of exposure to a rabid raccoon. In counties with 28–39 percent farmland, there was an 84 percent increased risk of exposure.

State, rurality, and percent of area designated as farmland were the best predictors of risk of raccoon rabies exposure. Further research is needed to better understand the effect of the oral rabies vaccine program in controlling the risk of human exposure to raccoon rabies.