BackgroundThe application of the Geographic Information Systems (GIS) to the study of vector transmitted diseases considerably improves the management of the information obtained from the field survey and facilitates the study of the distribution patterns of the vector species.MethodsAs part of a study to assess remote sensing data as a tool for vector mapping, geographical features like rivers, small streams, forest, roads and residential area were digitized from the satellite images and overlaid with entomological data. Map of larval breeding habitats distribution and map of malaria transmission risk area were developed using a combination of field data, satellite image analysis and GIS technique. All digital data in the GIS were displayed in the WGS 1984 coordinate system. Six occasions of larval surveillance were also conducted to determine the species of mosquitoes, their characteristics and the abundance of habitats.ResultsLarval survey studies showed that anopheline and culicine larvae were collected and mapped from 79 and 67 breeding sites respectively. Breeding habitats were located at 100-400 m from human settlement. Map of villages with 400 m buffer zone visualizes that more than 80% of Anopheles maculatus s.s. immature habitats were found within the buffer zone.ConclusionsThis study amplifies the need for a broadening of the GIS approach which is emphasized with the aim of rejuvenating the dynamic aspect of entomological studies in Malaysia. In fact, the use of such basic GIS platforms promote a more rational basis for strategic planning and management in the control of endemic diseases at the national level.

Malaria control programme utilizing indoor residual spraying of chemical insecticide is only effective if a high coverage of targeted area is achieved. The effectiveness of the residual spraying, on the other hand, relies on the efficacy and residual activity of the insecticides applied, which to a certain extent are influenced by the nature of the sprayed surfaces. The bioefficacy of indoor residual-sprayed deltamethrin wettable granule (WG) formulation for the control of malaria was compared with the current dose of deltamethrin wettable powder (WP) in malaria endemic areas in Balai Ringin, Sarawak. Doses of 20 mg/m 2 WP (control), 20 mg/m 2 WG, 30 mg/m 2 WG and 40 mg/m 2 WG were sprayed separately on different surfaces namely, wooden, rough-bamboo, smooth-bamboo and brick surfaces. Residual activity of WP and WG formulations was tested against lab-bred Anopheles maculatus using WHO standard procedure. Deltamethrin at 30 mg/m 2 WG exhibited the highest sustainable level of effectiveness against An. maculatus (An. maculatus mortality was between 95%-100%) up to week 60 post-spraying when sprayed on smoothbamboo surface. These results indicated that 30 mg/m 2 WG could be an ideal concentration for controlling malaria vector effectively up to 15 months of which long-lasting residual spraying was envisaged. The usual two spraying cycles per year with 20 mg/m 2 deltamethrin WP could be replaced with 30 mg/m 2 deltamethrin WG since the long residual activity was achieved by employing a single spraying only.

Knowledge of the composition and biting habits of mosquito associated with endemic areas is important in establishing sound vector control programmes and understanding the epidemiology of vector borne diseases. The biting activity cycle of several mosquito species in Serian, Sarawak was observed and described. Collections were carried out indoors and outdoors for 12 hours from 6.00 pm to 6.00 am using human landing catch techniques. A total of 7271 mosquitoes comprising 27 species belonging to six genera were collected. Mansonia bonneae (23.6%) was the predominant species caught in the study areas followed by Culex vishnui (22.3%), Culex pseudovishnui (19.6%) and Culex tritaenorhynchus (13.7%). A high rate of human biting activity by Ma. bonneae was detected during November but the activity was low during January. The biting activity of Ma. bonneae was found higher outdoor compared to indoor and peaked at 7.00 pm-8.00 pm. Cx. vishnui also exhibited similar biting activity peak while Anopheles letifer exhibited biting activity peaked at 12.00 am-1.00 am. Cx. pseudovishnui showed biting patterns which were almost similar between indoor and outdoor activity and could be considered active throughout the 12 hour period.

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