22 recapture experiments and examined the Ae. aegypti flight range and dispersal patterns [65]. Throughout these exten- sive experiments, the majority of mosquitoes were collected from their release house or the adjacent house. Adult Ae. aegypti disperse over relatively short distances, and inter- village movement was detected only rarely. The authors (2005) therefore suggested that people rather than mosquitoes are the primary mode of dengue virus dissemination within and among communities [65]. For Ae. albopictus, several mark-release-recapture experiments were conducted to examine the movement of the species in the domestic environment in Nagasaki, Japan. Takagi et al. [29–31] showed that trivial movement of Ae. albopictus occurred among sites and that the distribution of the released females overlapped with that of wild mosquitoes after a few days of release through trivial movement. Even among vegetation sites, there was a site with a high density of Ae. albopictus as compared to the other vegetation sites. Dispersal was influenced by larval rearing conditions as well. Ae. albopictus females emerging from high larval densities dispersed more often over a considerable distance than those from low larval densities [66]. These studies suggest that dispersal and movement of Ae. aegypti and Ae. albopictus around houses is largely influenced by larval breeding sites, buildings and vegetation in the domestic environment. Microclimate and the avail- ability of hosts also affected dispersal and distribution of dengue vectors [67, 68]. From the entomological viewpoint, the epidemiology of DF/DHF may vary depending on locality because of modified distribution and movement of vector mosquitoes among localities. Thus, environmental assessment at the household level is necessary for dengue control [69]. It was observed that the density of Ae. aegypti varied among houses. In a temple in Thailand, Ae. aegypti and Ae. albopictus were collected from five different buildings used as bedrooms, kitchen, pray room, bell-ringing room and sermon room at four intervals. The movement of people was also observed and estimated as a score calculated as follows: the number of people × time spent in a building in a day × number of days in a week. This score was considered to represent the degree of human presence. Density of Ae. aegypti was positively correlated with the scores derived from each building (Higa et al., unpublished data). For Ae. albopictus, the presence of vegetation around buildings was more important than the human presence. The human presence in a building seems highly important for Ae. aegypti and influences the density among houses. Tropical Medicine and Health Vol.39 No.4 Supplement, 2011 CURRENT DISTRIBUTION BY CLIMATE CHANGE, TRANSPORTATION AND TRADE ON A CONTINENTAL SCALE Climate change For vector-borne diseases, a higher temperature within a range of survival of vectors will enhance reproduction of vector mosquitoes and elongate the yearly period of repro- ductivity [3, 70]. The incubation period of viruses mean- while will be shortened [71]. The recent enhancement of DF/DHF transmission and expansion of the geographic range of the diseases and vector mosquitoes are matters of great concern in that they may be influenced by the global warming trend associated with climate change [72]. Since DF/DHF vaccine is unavailable for practical use and the viruses circulate mainly between human and vector mosquitoes, vector presence is a limiting factor of trans- mission. Since vector-borne diseases are usually tropical diseases, medical entomologists are keenly interested in the effects of global warming on vector distributions at higher latitudes. Kobayashi et al. (2002) clearly showed the relationship between the expansion of Ae. albopictus northward and temperature increases including the annual mean temperature above 11°C, January mean temperature, number of days above 11°C per year, and the total accumu- lated temperature in Japan using Geographical Information Systems (GIS) [55]. Although it is not so easy to demonstrate how the current spread of DF/DHF is related to the geographic expansion of mosquito vectors by climate change, recent computer and remote sensing technologies have allowed researchers to analyze enormous datasets with satellite pictures, GIS and distribution-modeling software easily affordable [73]. These tools have made it possible to predict vector distribution in changing environments. The results of related studies suggest that human behavioral change exerts a more significant impact than climate change on the geo- graphical expansion of dengue vectors [58, 74, 75]. Beebe et al. (2009) analyzed past Ae. aegypti collection data and temperature in Australia and concluded that the increased risk of an Ae. aegypti range expansion in Australia is due not directly to climate change but rather to human adapta- tion to current and forecasted regional drying through the installation of large domestic water storage containers [58]. Global warming enhances the usage of air conditioners, which means that windows are closed and people are less vulnerable to mosquito bites, but frequent use of drinking cans and bottles which can be larval breeding sites may result in increased vulnerability. Events caused by climate change are dynamic and sub- sequent impacts on vector mosquitoes by unknown factors