The relationship between mosquito abundance and rice field density in the Republic of Korea.
BACKGROUND
Japanese encephalitis virus (JEV), the causative agent of Japanese encephalitis (JE), is endemic to the Republic of Korea (ROK) where unvaccinated United States (U.S.) military Service members, civilians and family members are stationed. The primary vector of the JEV in the ROK is Culex tritaeniorhynchus. The ecological relationship between Culex spp. and rice fields has been studied extensively; rice fields have been shown to increase the prevalence of Cx. tritaeniorhynchus. This research was conducted to determine if the quantification of rice field land cover surrounding U.S. military installations in the ROK should be used as a parameter in a larger risk model that predicts the abundance of Cx. tritaeniorhynchus populations. Mosquito data from the U.S. Forces Korea (USFK) mosquito surveillance program were used in this project. The average number of female Cx. tritaeniorhynchus collected per trap night for the months of August and September, 2002-2008, was calculated. Rice fields were manually digitized inside 1.5 km buffer zones surrounding U.S. military installations on high-resolution satellite images, and the proportion of rice fields was calculated for each buffer zone.


RESULTS
Mosquito data collected from seventeen sample sites were analyzed for an association with the proportion of rice field land cover. Results demonstrated that the linear relationship between the proportion of rice fields and mosquito abundance was statistically significant (R2 = 0.62, r = .79, F = 22.72, p < 0.001).


CONCLUSIONS
The analysis presented shows a statistically significant linear relationship between the two parameters, proportion of rice field land cover and log10 of the average number of Cx. tritaeniorhynchus collected per trap night. The findings confirm that agricultural land cover should be included in future studies to develop JE risk prediction models for non-indigenous personnel living at military installations in the ROK.
Richards
Erin E
EE
Department of Preventive Medicine and Biometrics, Uniformed Services University, Bethesda, Maryland, USA. erin.e.richards@us.army.mil
Masuoka
Penny
P
Brett-Major
David
D
Smith
Matthew
M
Klein
Terry A
TA
Kim
Heung Chul
HC
Anyamba
Assaf
A
Grieco
John
J
D000383:Agriculture; D000818:Animals; D009033:Culicidae / Q000821:virology*; D004664:Encephalitis Virus, Japanese / Q000302:isolation & purification*; D004672:Encephalitis, Japanese / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control*; D005260:Female; D006801:Humans; D015994:Incidence; D007303:Insect Vectors / Q000821:virology*; D022321:Japanese Encephalitis Vaccines / Q000008:administration & dosage; D016014:Linear Models; D008297:Male; D008889:Military Personnel; D012275:Oryza; D056910:Republic of Korea / Q000453:epidemiology; D012189:Retrospective Studies; D012307:Risk Factors; D012621:Seasons; D014611:Vaccination
D022321:Japanese Encephalitis Vaccines