Modeling the distribution of Culex tritaeniorhynchus to predict Japanese encephalitis distribution in the Republic of Korea

• Main Authors: Penny Masuoka, Terry A. Klein, Heung-Chul Kim, David M. Claborn, Nicole Achee, Richard Andre, Judith Chamberlin, Jennifer Small, Assaf Anyamba, Dong-Kyu Lee, Suk H. Yi, Michael Sardelis, Young-Ran Ju, John Grieco
• Format: Article
• Language: English
• Published: PAGEPress Publications 2010-11-01
• Series: Geospatial Health
• Subjects: Culex tritaeniorhynchus, geographical distribution, ecological niche modeling, Japanese encephalitis virus, Republic of Korea.
• Online Access: http://www.geospatialhealth.net/index.php/gh/article/view/186

Over 35,000 cases of Japanese encephalitis (JE) are reported worldwide each year. <em>Culex tritaeniorhynchus</em> is the primary vector of the JE virus, while wading birds are natural reservoirs and swine amplifying hosts. As part of a JE risk analysis, the ecological niche modeling programme, Maxent, was used to develop a predictive model for the distribution of <em>Cx. tritaeniorhynchus</em> in the Republic of Korea, using mosquito collection data, temperature, precipitation, elevation, land cover and the normalized difference vegetation index (NDVI). The resulting probability maps from the model were consistent with the known environmental limitations of the mosquito with low probabilities predicted for forest covered mountains. July minimum temperature and land cover were the most important variables in the model. Elevation, summer NDVI (July-September), precipitation in July, summer minimum temperature (May-August) and maximum temperature for fall and winter months also contributed to the model. Comparison of the <em>Cx. tritaeniorhynchus</em> model to the distribution of JE cases in the Republic of Korea from 2001 to 2009 showed that cases among a highly vaccinated Korean population were located in high-probability areas for <em>Cx. tritaeniorhynchus</em>. No recent JE cases were reported from the eastern coastline, where higher probabilities of mosquitoes were predicted, but where only small numbers of pigs are raised. The geographical distribution of reported JE cases corresponded closely with the predicted high-probability areas for <em>Cx. tritaeniorhynchus</em>, making the map a useful tool for health risk analysis that could be used for planning preventive public health measures.