Abstract
Japanese encephalitis (JE) is the major cause of viral encephalitis (VE)
in most Asian-Pacific countries. In Vietnam, there is no nationwide
surveillance system for JE due to lack of medical facilities and
diagnoses. Culex tritaeniorhynchus, Culex Vishnui, and Culex
quinquefasciatus have been identified as the major JE vectors in
Vietnam. The main objective of this study was to forecast a risk map of
Culex mosquitoes in Hanoi, which is one of the most densely populated
cities in Vietnam. A total of 10,775 female adult Culex mosquitoes were
collected from 513 trapping locations. We collected temperature and
precipitation information during the study period and its preceding
month. In addition, the other predictor variables (e.g., normalized
difference vegetation index [NDVI], land use/land cover and human
population density), were collected for our analysis. All the collected
data was pre-processed with the same study extent and spatial resolution
of 30 m. The final model selected for estimating the Culex mosquito
abundance included centered rainfall, quadratic term rainfall, rice
cover ratio, forest cover ratio, and human population density variables.
The estimated spatial distribution of Culex mosquito abundance ranged
from 0 to 200. Our model estimated that 87% of the Hanoi area had an
abundance of mosquitoes from 0 to 50, whereas approximately 1.2% of the
area showed more than 150 mosquitoes, which was mostly in the
rural/peri-urban districts. Our findings may provide better insight into
understanding the spatial distribution of Culex mosquitoes and its
associated environmental risk factors. Such information can assist local
clinicians and public health policymakers to identify the potential
areas of risk for JE virus. Risk maps can be an efficient way of raising
public awareness about the virus and further preventive measures need to
be considered in order to prevent outbreaks and onwards transmission of
the JE virus.