Intersectoral technologies are those that involve collaboration between health and other sectors. Recent experiences with the control of emerging and resurging diseases, e.g., dengue, have shown that emergency responses by the health sector have limited success - usually because they are begun too late to have any effect. There is a need to think more broadly than the health sector for effective interventions for infectious disease threats (Pinheiro and Corber, 1997; Gubler, 1989).
Collaboration across research disciplines is essential. For example, the use of a hydrological soil moisture model to forecast Anopheles mosquito biting rates in Kenya was only possible because of collaboration between epidemiologists, entomologists and hydrologists (Patz et al., 1998). Barriers to global change research include: the lack of national strategic research plans; lack of communication between disciplines; single-discipline funding agencies that do not fund interdisciplinary research; the pressure of other existing health needs; and the lack of public concern, which would increase priority with decision-makers (CGCP, 1995).
Integrated Environmental Management
The environmental management of ecosystems upon which health depends (i.e., freshwater resources, agricultural areas) should be improved. The incidence of certain water-borne and vector-borne infections can be reduced by several environmental measures. Experience with the WHO/FAO/UNEP/UNCHS Panel of Experts on Environmental Management (PEEM) has shown that early consultations between health and agricultural sectors can greatly reduce the burden of vector-borne diseases (e.g., malaria, schistosomiasis) in large-scale irrigation projects by appropriate adaptations in the management of irrigation water (FAO, 1987). Likewise, collaboration between oceanographers, marine biologists and fisheries experts should lead to the delineation of non-fishing zones on coral reefs, to maintain fish breeding sites and to provide sentinel sites for the undistorted monitoring of ocean warming effects.
Traditional public health interventions for water- and food-borne diseases, which focus on personal hygiene and food safety, have limited effectiveness. A broader approach would consider the interactions between climate, vegetation, agricultural practices and human activity. For example, some farming practices remove vegetation from hillsides and river banks, increasing run-off, leading in turn to more erosion and sedimentation, and the retention of encysted pathogens from livestock excrement. Ecological analysis can result in recommendations for the type, time and place of public health interventions, such as changes in management of water catchment areas, or targeting water treatment to cover high risk periods.
Strategies to control the invasion of climate-sensitive disease vector and pest species require intersectoral collaboration between the health, forestry, environment, and conservation sectors. Climate change is likely to amplify the challenge of pest control, as new ecological niches appear that may sustain exotic pathogens and disease vectors. The recent establishment of the Environmental Risk Management Authority (ERMA) in New Zealand is an example of such a strategy (Anon, 1996). As an evolutionarily-isolated island ecosystem New Zealand is particularly vulnerable to invading species (Leakey and Lewin, 1996). ERMA provides an integrated approach with a wide-ranging brief that includes regulation of importation, investigation of incidents and emergencies, and review of existing hazards. The Authority has formal links with many sectors, must consider public input from diverse interest groups, and reports directly to a senior Minister who holds both the Environment and Biosecurity portfolios.
Within the next decade, more than half the world's population (more than 3.3 billion people) will be living in cities (WRI, 1997). Rapid urbanisation has many adverse environmental and health consequences, and health inequalities between rich and poor are widest in cities of developing countries. Current strategies to reduce poverty and vulnerability to climate variability in urban environments will serve to enhance adaptation to the health impacts of climate change. Some examples are described below.
Natural Disasters: Land use planning can reduce vulnerability to weather disasters by maintaining strict control over any development in high-risk zones and to discourage human settlement in such zones. In addition, governments must ensure that buildings and the urban infrastructure are built to withstand extreme events. Populations in shanty settlements in developing countries are very vulnerable to climate variability, as structures are often flimsy and located on land subject to frequent flooding. Future projections of land-use changes indicate that in many countries the poorest population sectors will congregate increasingly on the land that is most vulnerable to the impacts of natural disasters. Therefore, these countries need to formulate national disaster-response strategies as part of their sustainable development planning.
Urban micro-climates: At the local scale, human activities alter the climate in cities principally by the "heat island" effect that increases temperatures and decreases precipitation. The heat island effect can be reduced by appropriate urban planning (Oke, 1997), including improved insulation of buildings and other design features that reduce heat load, planting trees, and selection of materials with high albedo for roads, parking lots and roofs.
Water quality: A large urban population in developing countries currently does not have access to a safe drinking water source (standpipe or borehole) or to sanitation services (sewers, septic tanks or wet latrines) (WRI, 1997). Flooding may become more frequent with climate change and can affect health through the spread of disease. The only way to reduce vulnerability is to build the infrastructure to remove solid waste and waste water, and to supply potable water. No sanitation technology is "safe" when covered by flood waters, as faecal matter mixes with flood waters and is spread wherever the flood waters go. The usual focus of drainage design on the performance of the minor drainage system (pipes, channels, and overflows) neglects the performance of the major drainage system, including flows over land and in the streets, which occurs during major floods. As the risk of flooding increases with climate change, so does the importance of the major drainage system. New design approaches, which explicitly design roads to act as drains, can radically reduce the duration of flooding. Litter management is critical to the management of urban drainage systems; often the best investment in drainage is better handling of solid waste to prevent systems becoming rapidly blocked with debris.
Early Warning Systems
Weather and climate forecasts may be used, where appropriate, in preventing deaths, injuries and in disease prevention and control. The five-day weather forecasts, achieved over the last decade and now routine in many countries, have saved millions of lives through warnings of hurricanes, floods and other severe weather (Noji, 1997). For example, deaths due to tropical cyclones in South Asia have been dramatically reduced due to meteorological forecasts, systems to disseminate forecasts and the building of storm shelters. The use of historical climate data for planning may reduce food insecurity in many countries. However, meteorological and related services are not used to their full potential in mitigating the adverse health impacts of climate variability.
Illness and deaths due to heatwaves can be prevented by hot weather watch/warning systems, which alert people to impending dangerous weather and provide information on how to avoid illness during weather extremes (Kalkstein et al., 1996). Sentinel surveillance in emergency departments can also be used to monitor increases in heat-related cases (Kellermann and Todd, 1996).
Seasonal regional climate forecasts have proved useful in guiding farmers in Brazil, Zimbabwe, Peru, and other countries in the planting of drought resistant crops and management of fisheries during El Niño years (Glantz, 1996). Seasonal forecasts have been included into many local and regional famine and drought early warning systems (Glantz, 1994). Associations between El Niño and malaria epidemics in Asia and South America have also been described (Bouma and Dye, 1997; Bouma and van der Kaay, 1996; Kovats et al., 1999). The use of climate forecasts for epidemic forecasting needs to be incorporated with early warning systems based on known epidemic risk factors (e.g., heavy rainfall). Initiatives that are underway in East and Southern Africa and India to develop these new approaches for the surveillance and control of epidemic malaria should be supported.
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