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ARS Home » Southeast Area » Gainesville, Florida » Center for Medical, Agricultural and Veterinary Entomology » Imported Fire Ant and Household Insects Research » Research » Publications at this Location » Publication #84839
Title: THE USE OF SPATIAL ANALYSIS IN THE CONTROL AND RISK ASSESSMENT OF VECTOR-BORNE DISEASES

Author
item Focks, Dana
item Brenner, Richard
item CHADEE, DAVE - TRINIDAD, WI
item TROSPER, JAMES - MINISTRY OF HEALTH

Submitted to: American Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/18/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Dengue Hemorrhagic Fever (DHF) is a serious viral disease of humans living in the tropics. It is transmitted from person to person through the bite of several species of Aedes mosquitoes which breed in and around houses in water-holding containers such as laundry sinks, drums, flower vases, and discarded tires and trash. Because there is no vaccine, attempting to control DHF has always involved insecticide sprays or a clean-up campaign designed to reduce the number of mosquito-producing containers. Managing this disease has always been expensive and difficult because no one knew where or when mosquito populations within a city were high enough to be dangerous. Scientists at the Center for Medical, Agricultural and Veterinary Entomology in Gainesville, FL, have devised a simple method for measuring and displaying mosquito distributions based on the same principles used to make contour maps. Data from a survey of water-holding statistics (geostatistics) allowing the construction of detailed contour maps showing the total distribution of mosquitoes. Using this "precision targeting" map, dengue control personnel can direct control efforts at only those locations where mosquito populations are high and transmission is possible. Post-treatment contour maps reveal the extent of the control and where additional interventions may be needed. The procedures described by the scientists can be done with commercially-available software to achieve cost-effective dengue control with minimum environmental contamination, and minimal knowledge about the behavior and biology of dengue mosquitoes.

Technical Abstract: Two case studies are presented with the goal of demonstrating the usefulness of spatial statistics in the area of vector-borne disease. In Hawaii, the spatial distribution of Aedes albopictus oviposition within a small military facility located within a forest preserve indicated that the source of adult mosquitoes on the base was the untreatable sylvan areas surrounding the base. A simple spatial analysis of oviposition during weeks with and without insecticide aerosol applications indicated that treatments were ineffective. These analyses led to the conclusion that if source reduction was not a viable alternative, then, without a tangible threat of Ae. albopictus-borne illness, no insecticide control measures should be attempted on the base. Regarding the Trinidad studies, spatial visualization demonstrated dramatically that the traditional Stegomyia indices should no longer be considered viable surrogates of dengue transmission risk as they did not correlate spatially with themselves nor with the absolute densities of Aedes aegypti. Spatial visualization of the number of pupae per person indicated that the threat of dengue was not uniformly distributed throughout the island. Spatial analysis of site differences in the types, frequencies, and productivities of water holding domestic and trash containers indicated that targeted source reduction programs would have outcomes that varied spatially, perhaps justifying tailoring control efforts on a site-by-site basis.