Patricia Ellen Dale

Climate change and dengue: a critical and systematic review of quantitative modelling approaches

BackgroundMany studies have found associations between climatic conditions and dengue transmission. However, there is a debate about the future impacts of climate change on dengue transmission. This paper reviewed epidemiological evidence on the relationship between climate and dengue with a focus on quantitative methods for assessing the potential impacts of climate change on global dengue transmission.MethodsA literature search was conducted in October 2012, using the electronic databases PubMed, Scopus, ScienceDirect, ProQuest, and Web of Science. The search focused on peer-reviewed journal articles published in English from January 1991 through October 2012.ResultsSixteen studies met the inclusion criteria and most studies showed that the transmission of dengue is highly sensitive to climatic conditions, especially temperature, rainfall and relative humidity. Studies on the potential impacts of climate change on dengue indicate increased climatic suitability for transmission and an expansion of the geographic regions at risk during this century. A variety of quantitative modelling approaches were used in the studies. Several key methodological issues and current knowledge gaps were identified through this review.ConclusionsIt is important to assemble spatio-temporal patterns of dengue transmission compatible with long-term data on climate and other socio-ecological changes and this would advance projections of dengue risks associated with climate change.

Wetlands and Mosquitoes: a review

This review brings together information on mosquitoes, the diseases they transmit and the wetlands that provide habitats for the immature stages (eggs and larvae). Wetland values are mentioned, though the main literature on this does not generally overlap the mosquito issue. Mosquito management is overviewed to include: the use of larvicides, source reduction in intertidal wetlands and management in freshwater systems. There is not a great deal of information on mosquitoes and freshwater systems, except for constructed wetlands and they are considered separately. We then consider restoration mainly in the context of wetlands that have been the subject of habitat modification for mosquito control. Land use and climate change, as they affect mosquitoes and the diseases they transmit, are also reviewed, as this will affect wetlands via management activities. Finally the review addresses the critical issue of balancing health, both human and environmental, in an adaptive framework. It concludes that there is a need to ensure that both mosquito and wetland management communicate and integrate to sustain wetland and human health.

IDENTIFYING WETLAND CHANGE IN CHINA'S SANJIANG PLAIN USING REMOTE SENSING

Maximum likelihood supervised classification and post-classification change detection techniques were applied to Landsat MSS/TM images acquired in 1976, 1986, 1995, 2000, and 2005 to map land cover changes in the Small Sanjiang Plain in northeast China. A hotspots study identified land use changes in two National Nature Reserves. These were the Honghe National Nature Reserve (HNNR) and the Sanjiang National Nature Reserve (SNNR). Landscape metrics were used in both reserves to identify marsh landscape pattern dynamics. The results showed that the Small Sanjiang plain had been subject to much change. This resulted from direct and indirect impacts of human activities. Direct impacts, resulting in marsh loss, were associated with widespread reclamation for agriculture. Indirect impacts (mainly in HNNR) resulted from alterations to the marsh hydrology and this degraded the marsh ecosystem. Marsh landscape patterns changed significantly due to direct impacts in SNNR between 1976 and 1986 and again between 2000 and 2005, and, in HNNR between 1976 and 1986. Indirect impacts in HNNR after 1986 appeared to cause little change. It was concluded that effective wetland protection measures are needed, informed by the change analysis.

Challenges in using geographic information systems (GIS) to understand and control malaria in Indonesia

Malaria is a mosquito-borne disease of global concern with 1.5 to 2.7 million people dying each year and many more suffering from it. In Indonesia, malaria is a major public health issue with around six million clinical cases and 700 deaths each year. Malaria is most prevalent in the developing countries of the world. Aid agencies have provided financial and technical assistance to malaria-prone countries in an effort to battle the disease. Over the past decade, the focus of some of this assistance has been in the provision of geographic information systems (GIS) hardware, software and training. In theory, GIS can be a very effective tool in combating malaria, however, in practice there have been a host of challenges to its successful use.This review is based, in part, on the literature but also on our experience working with the Indonesian Ministry of Health. The review identifies three broad problem areas. The first of these relates to data concerns. Without adequate data, GIS is not very useful. Specific problem areas include: accurate data on the disease and how it is reported; basic environmental data on vegetation, land uses, topography, rainfall, etc.; and demographic data on the movement of people. The second problem area involves technology – specifically computer hardware, GIS software and training. The third problem area concerns methods – assuming the previous data and technological problems have been resolved – how can GIS be used to improve our understanding of malaria? One of the main methodological tools is spatial statistical analysis, however, this is a newly developing field, is not easy to understand and suffers from the fact that there is no agreement on standard methods of analysis.The paper concludes with a discussion of strategies that can be used to overcome some of these problems. One of these strategies involves using ArcView GIS software in combination with ArcExplorer (a public domain program that can read ArcView files) to deal with the problem of needing multiple copies of GIS software. Another strategy involves the development of a self-paced training package that can be used to train individuals

Interdisciplinary foundations: reflecting on interdisciplinarity and three decades of teaching and research at Griffith University, Australia

Interdisciplinarity is widely practised and theorised. However, relatively few studies have reflected on university‐wide attempts to foster the concept. This article examines interdisciplinary teaching and learning at Griffith University, Australia. It reflects on the foundations of interdisciplinarity at the university and situates them within the broader context of innovations in worldwide practice; it draws from the literature on interdisciplinarity to traverse the broad understandings of the term; it discusses the Griffith University innovations implemented in support of the concept; and, it reports on the likely outcomes of current methods designed to improve interdisciplinary practice. Whilst challenging barriers to interdisciplinarity continue to exist, compounded by varied conceptions of what interdisciplinarity entails, positive learning and research outcomes have been accomplished at the university from its interdisciplinary foundations, which also provide a platform to go forward.

Habitat characteristics and eggshell distribution of the salt marsh mosquito, Aedes vigilax, in marshes in subtropical Eastern Australia.

Abstract Research at 10 locations in coastal subtropical Queensland, Australia, has shown that salt marshes contained heterogeneous distributions of eggshells of the pest and vector mosquito Aedes vigilax (Skuse) (Diptera:Culicidae). The eggshell distribution was related to specific vegetation assemblages, with a mix of the grass, Sporobolus virginicus (L.) Kunth (Poales: Poaceae), and the beaded glasswort, Sarcocornia quinqueflora (Bunge ex (Ung.-Stern) A.J. Scott (Caryophyllales: Chenopodiaceae), as significantly higher in eggshells than any other vegetation. There were also high numbers in the mix of S. virginicus with the arrowgrass, Triglochin striata Ruiz & Pavón (Alismatales: Juncaginaceae). Both mixed types are found in relatively wetter areas, despite very few eggshells being found generally in the low marsh. Most sites contained S. virginicus and eggshell locations were variable for this species alone. This was probably related to its life form variability in response to salinity and location on the marsh. Location on the marsh was important for eggshell distribution with most eggshells around the edges of pools and depressions, followed by, but to a significantly lesser extent, the marsh surface. Eggshells were fewest in the low marsh. Partition analysis resulted in a tree that simplified and summarised the factors important for eggshell distribution confirming the individual analyses. The potential effects of climate, sea level and other change are also briefly discussed in the context of likely changes to land cover and relative location on the marsh. For example, increased sea level may lead to low marsh conditions extending into higher marsh area with implications for oviposition and numbers of eggshells.

Mosquito species (Diptera: Culicidae) and the transmission of ross river virus in Brisbane, Australia

Abstract This study aimed to identify the major mosquito vectors of Ross River virus (family Togaviridae, genus Alphavirus, RRV) and to explore the threshold of mosquito abundance necessary for RRV transmission in Brisbane, Australia. Data on the monthly counts of RRV cases by statistical local areas from the Queensland Health and the monthly mosquito abundance in Brisbane between November 1998 and December 2001 from the Brisbane City Council were used to assess the pairwise relationship between mosquito abundance and the incidence of RRV disease over a range of time lags using cross-correlations. We used time series Poisson regression models to identify major mosquito species associated with incidence of RRV after adjusting for overdispersion, maximum temperature, autocorrelation, and seasonality. Our results show that Aedes vigilax (Skuse) (relative risk [RR] = 1.32; 95% CI = 1.01–1.74 per 100 mosquitoes per trap) and Culex annulirostris (Skuse) (RR = 1.14, 95% CI = 1.04–1.24 per 100 mosquitoes per trap) were most strongly associated with RRV transmission at a lag of 1 mo. Classification and regression tree (CART) analyses indicate that the occurrence of RRV was associated with an average monthly mosquito abundance of Aedes vigilax above 72 and Cx. annulirostris above 52. The validation analyses indicate that the crude agreement between predicted values and actual observations was 76% (sensitivity, 61%; specificity, 80%). The results may have applications as a decision support tool in planning disease control and risk-management programs.

Climate Variability, Social and Environmental Factors, and Ross River Virus Transmission: Research Development and Future Research Needs

Background Arbovirus diseases have emerged as a global public health concern. However, the impact of climatic, social, and environmental variability on the transmission of arbovirus diseases remains to be determined. Objective Our goal for this study was to provide an overview of research development and future research directions about the interrelationship between climate variability, social and environmental factors, and the transmission of Ross River virus (RRV), the most common and widespread arbovirus disease in Australia. Methods We conducted a systematic literature search on climatic, social, and environmental factors and RRV disease. Potentially relevant studies were identified from a series of electronic searches. Results The body of evidence revealed that the transmission cycles of RRV disease appear to be sensitive to climate and tidal variability. Rainfall, temperature, and high tides were among major determinants of the transmission of RRV disease at the macro level. However, the nature and magnitude of the interrelationship between climate variability, mosquito density, and the transmission of RRV disease varied with geographic area and socioenvironmental condition. Projected anthropogenic global climatic change may result in an increase in RRV infections, and the key determinants of RRV transmission we have identified here may be useful in the development of an early warning system. Conclusions The analysis indicates that there is a complex relationship between climate variability, social and environmental factors, and RRV transmission. Different strategies may be needed for the control and prevention of RRV disease at different levels. These research findings could be used as an additional tool to support decision making in disease control/surveillance and risk management.

Climatic, high tide and vector variables and the transmission of Ross River virus

Abstract

Weather variability, tides, and Barmah Forest virus disease in the Gladstone region, Australia.

In this study we examined the impact of weather variability and tides on the transmission of Barmah Forest virus (BFV) disease and developed a weather-based forecasting model for BFV disease in the Gladstone region, Australia. We used seasonal autoregressive integrated moving-average (SARIMA) models to determine the contribution of weather variables to BFV transmission after the time-series data of response and explanatory variables were made stationary through seasonal differencing. We obtained data on the monthly counts of BFV cases, weather variables (e.g., mean minimum and maximum temperature, total rainfall, and mean relative humidity), high and low tides, and the population size in the Gladstone region between January 1992 and December 2001 from the Queensland Department of Health, Australian Bureau of Meteorology, Queensland Department of Transport, and Australian Bureau of Statistics, respectively. The SARIMA model shows that the 5-month moving average of minimum temperature (β = 0.15, p-value < 0.001) was statistically significantly and positively associated with BFV disease, whereas high tide in the current month (β = −1.03, p-value = 0.04) was statistically significantly and inversely associated with it. However, no significant association was found for other variables. These results may be applied to forecast the occurrence of BFV disease and to use public health resources in BFV control and prevention.