|
|
||||||||
Information on the spatial relationships between disease vectors and environmental factors is fundamental to vector-borne disease control. Although it is well known that mosquito abundance is associated with the amount of rainfall and thus the number of larval breeding sites, the spatial relationship between larval habitat availability and adult mosquito abundance is not clear. We investigated the impact of environmental heterogeneity and larval habitats on the spatial distribution of Anopheles gambiae s. s. and An. funestus adult mosquitoes, the most important malaria vectors in the highlands of western Kenya. Mosquito sampling was conducted in May, August, and November 2002, and February 2003. Geographic information system layers of larval habitats, land use type, human population distribution, house structure, and hydrologic schemes were overlaid with adult mosquito abundance. Correlography was used to determine the spatial autocorrelation in adult mosquito abundance among houses and the cross-correlation between adult mosquito abundance and environmental factors. Getis Gi*(d) index was used to define focal adult mosquito abundance clusters. We found a significant autocorrelation in the vector population and a significant cross-correlation between the vector population and larval habitat availability. The threshold distances of both autocorrelation and cross-correlation were significantly varied among seasons. Focal clustering analysis revealed that the adult vector population was concentrated along the Yala River Valley where most larval habitats were found. Regression analysis found that distance of a house to the Yala River, age of the house, elevation, house structure, and tree canopy coverage significantly affected adult mosquito abundance. Our results suggest that vector control targeted at malaria transmission hotspots and supplemented by larval control may be an effective approach for epidemic malaria control in the western Kenya highlands.
Received December 29, 2006. Accepted for publication March 30, 2007.
Acknowledgments: We thank Maurice Okonji, Stephen Ajuma, Peter A. Lutiali, Wilberforce Miheso, and Amos Wabwile for technical assistance, and two anonymous reviewers for valuable comments and suggestions. This paper is published with the permission of the Director of the Kenya Medical Research Institute.
Financial support: This work was supported by National Institutes of Health grants R01 AI 50243 and D43 TW01505.
* Address correspondence to Guofa Zhou, Program in Public Health, College of Health Sciences, University of California, 3501 Hewitt Hall, Irvine, CA 92697. E-mail: zhoug{at}uci.edu
Authors addresses: Guofa Zhou and Guiyun Yan, Program in Public Health, College of Health Sciences, University of California, Irvine, CA 92697, E-mails: zhoug{at}uci.edu and guiyuny{at}uci.edu. Stephen Munga and Andrew K. Githeko, Kenya Medical Research Institute, Kisumu, Kenya, E-mails: smunga{at}kisian.mimcom.net and agitheko{at}kisian.mimcom.net. Noboru Minakawa, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga 849-8501, Japan, E-mail: minakawa{at}post.sagamed.ac.jp.
Reprint requests: Guiyun Yan, Program in Public Health, College of Health Sciences, University of California, Irvine, CA 92697.
This article has been cited by other articles:
![]() |
P. J. Rosenthal Artesunate for the Treatment of Severe Falciparum Malaria N. Engl. J. Med., April 24, 2008; 358(17): 1829 - 1836. [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |