To a large degree, public health depends on safe drinking water, sufficient food, secure shelter and good social conditions. A changing climate could, and is likely, to impact on all of these elements. The IPCC report on the impact of climate change on public health indicates that there could be some localized benefits, including decreased winter deaths in temperate climates, and increases in food production in some high latitude regions. However, overall, the health impacts of a rapidly changing climate are likely to be negative, particularly in poor communities and the least developed countries. The WHO has estimated that climate change already causes over 150,000 deaths annually and this number is expected to rise in the next decade.
Some of the health effects of climate change include:
A major health concern regarding climate change is the increased prevalence and distribution of Malaria. Malaria is the most serious and common vector-borne disease in the world, with between 300 to 500 million cases and 2 million deaths worldwide each year, but most importantly, it is preventable and curable. Malaria mitigation strategies require a combination of preventive and curative treatment methods and close collaboration between the health and climate sectors. The timely provision of climate information with several months lead-time can be combined with a well-developed national and regional response strategy that allocates resources for public outreach and distribution of medication and insecticides well in advance.
Given the limited resources many tropical and sub-tropical countries have in detecting and controlling malaria outbreaks, seasonal climate predictions with high spatial resolution are necessary to prepare for the most effective response in well-targeted areas.
High altitude regions have been protected from endemic malaria because the parasite can not multiply and mosquitos can not develop efficiently in temperatures below 18°C. However, there appears to be an emergence of malaria in the African highlands which may be attributable to increasing temperatures associated with climate change.
Malaria and Climate Change
As global temperatures continue to rise and precipitation patterns appear to alter, it is important to have a system that allows public health practitioners to forecast where and when malaria epidemics may occur. Temperature, precipitation and humidity are considered risk factors for malaria transmission. Increasing temperature accelerates the rate of mosquito larval development, the frequency of blood feeding by adult females on humans, and reduces the time it takes the malaria parasites to mature in female mosquitoes. Increased rainfall creates additional breeding sites for mosquitoes, thus increasing their numbers.
Many countries in Africa do incorporate malaria early detection into their malaria control efforts. Early detection means carefully monitoring rates of malaria incidence, in order to detect an impending outbreak. Early detection can provide enough lead time (days to over a week) to deliver malaria control drugs to the affected region, and thereby minimize the morbidity and mortality associated with the outbreaks. In addition, the climate conditions favouring mosquito breeding, parasite development, and hence transmission need careful and constant monitoring.
Malaria Early Warning Programmes
An integrated framework for an epidemic Malaria Early Warning and Response System (MEWS) was developed by the Roll Back Malaria (RBM) Partners jointly with the International Research Institute for Climate and Society (IRI) and national ministries of health in Africa. MEWS includes seasonal forecasts and climate monitoring as well as vulnerability assessments, case surveillance and response planning. The first operational MEWS has now been put in place in the Southern African countries – with a focus on Botswana – and the initial results are promising. Climate outlooks, with three to four months’ lead-time, are required in responding to an imminent malaria epidemic and national level stockpiling of the supplies that may be needed to effectively respond. The Image to the right is part of the MEWS programme to compare current rainfall to past events which triggered outbreaks.
Climate Models and Malaria
A malaria early warning technique proposed by researchers at the European Centre for Medium-Range Weather Forecasts (ECMWF), the IRI and the Ministry of Health in Botswana incorporates climate forecasts from multi-model ensembles to predict when malaria risk will be at its peak, by examining climatic variables which influence the proliferation of mosquitoes. The team successfully deployed the technique in Botswana and was able to give policy-makers and health programme officers up to four months of advance notice.
An ensemble forecast model, based on the DEMETER project , predicts a probability distribution of climate scenarios and hence, peak times for malaria transmissions. Money was recently invested in a project lead by the Tanzania Meteorological Agency, studying the impacts of climate variability on malaria in Tanzania. The main objective of the project was to further develop and apply the DEMETER methodology of integrating seasonal forecasts and malaria statistics into an end-to-end early warning system for malaria outbreaks. A new database of clinical cases was collected and made available for the wider scientific community, the seasonal cycle of malaria outbreaks determined and the high risk areas identified.
WMO projects and Malaria
WMO, working together with the World Bank, the National Oceanic and Atmospheric Administration (NOAA) of the USA, the IRI, the European Commission, and the NMHSs, develops seasonal climate prediction in Africa with the establishment of the Regional Climate Outlook Forums (RCOFs) since 1996. An integral part of the RCOF sessions held since 2004 in the Southern Africa region and since 2007 in the East Africa-Greater Horn of Africa region is the Malaria Outlook Forum (MALOF) with the primary mission to establish an operational early warning system for malaria.
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