#GETArticleoftheWeek- Malaria and climate change in Africa by Chiamaka Uwalaka
Chiamaka H. Uwalaka
Public Health and Epidemiology Department,
Nigerian Institute of Medical Research, Yaba, Lagos, Nigeria
Malaria is the most common parasitic infectious disease in the world affecting humans and animals.1 About 90 percent of the world’s death due to malaria occur in Africa.2 Fifteen countries in Sub-Saharan Africa and India carried almost 80 percent of the global malaria burden.3 From 2030 to 2050, climate change is expected to cause approximately 250 000 additional deaths per year, from malnutrition, malaria, diarrhoea and heat stress4 Despite the optimistic statement of the U.S. Surgeon General in 1967 that the war on infectious diseases was over and we had won, emergence of infectious diseases has not ceased and never will.5 The WHO estimates that one-sixth of the illness and disability suffered worldwide is owing to vector-borne diseases, with more than half of the world’s population currently at risk.6 Vector-borne diseases are among the most well studied of the diseases associated with climate change, owing to their large disease burden, widespread occurrence and high sensitivity to climatic factors. The vector for malaria disease is the female anopheles mosquito with the majority of clinical disease for malaria caused by Plasmodium falciparum and mostly affecting young children, non-immune adults and pregnant women7 At a time when much money has been invested in scientific research in relation to detection, surveillance and protection against bioterrorist attack, the world is continuing to be under attack from nature’s own biological weapons – pathogens, and of particular significance are those that are deemed to be emerging.8 Climate and weather change are already exerting strong influences on health: increased deaths in heat waves, and in natural disasters such as floods, as well as changing patterns of life-threatening vector-borne diseases such as malaria and other existing and emerging infectious diseases are observed.9 Climate change is projected to alter the distribution of vector borne diseases and malaria is no exception. On Earth, human activities are changing the natural greenhouse resulting in climate change. Over the last century the burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO2). This happens because the coal or oil burning process combines carbon with oxygen in the air to make CO2. To a lesser extent, the clearing of land for agriculture, industry, and other human activities has increased concentrations of greenhouse gases. Changes in land use are also important sources of greenhouse gas emissions.
For example deforestation results in the emission of carbon dioxide to the atmosphere that was previously stored on the Earth’s surface in the form of trees and other vegetation, or locked up in soils.
This is why carbon dioxide is the most important gas in the man-made component of the greenhouse effect.
One of the major consequences of man-made greenhouse effect on climate change is increase in vector breeding capacity as the climate changes that have occurred over the previous century have significantly altered the areas climatically suitable for transmission.
For example, in Africa, areas that have become unsuitable for transmission, mainly through drying, have approximately equaled those that have become suitable areas owing to increased temperatures and greater precipitation. Destruction of forests to create new human settlements can increase local temperatures by 3–4oC and at the same time create breeding sites for malaria vectors.10 The changes in malaria distribution on a global scale are still an area of active research. Despite the strong connection between malaria and climate, there is still quite a bit of uncertainty about future malaria transmission rates worldwide mainly because there are many other factors that affect the spread of the disease including socioeconomic development, drug resistance, and immunity.11
In 2015, the WHO Executive Board endorsed a new work plan on climate change and health. This includes:
- Partnerships: to coordinate with partner agencies within the UN system, and ensure that health is properly represented in the climate change agenda.
- Awareness raising: to provide and disseminate information on the threats that climate change presents to human health, and opportunities to promote health while cutting carbon emissions. • Science and evidence: to coordinate reviews of the scientific evidence on the links between climate change and health, and develop a global research agenda.
- Support for implementation of the public health response to climate change: to assist countries to build capacity to reduce health vulnerability to climate change, and promote health while reducing carbon emissions.
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2CDC. Where Malaria Occurs. 2018. Retrieved from https://www.cdc.gov/malaria/about/distribution.html on 5/7/19
3WHO. Climate Change. 2019. Retrieved from: https://www.afro.who.int/health-topics/climate-change on 30/8/19.
4WHO. Vector Borne Diseases. 2019. Retrieved from: https://www.who.int/news-room/fact-sheets/detail/vector-borne-diseases on 31/8/19.
5Dong J, Olano JP, McBride JW, Walker DH. Emerging Pathogens: Challenges and Successes of Molecular Diagnostics. Journal of Molecular Diagnosis. 2008; 10(3): 185–197.
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7 Beeson JG, Brown GV. Pathogenesis of Plasmodium falciparum malaria: the role of parasite adhesion and antigenic variation. Cellular and Molecular Life Sciences. 2002; 59: 258-272.
8 Millar C, Moor JE. Emerging pathogens in infectious diseases: Definitions, causes and trends. Reviews in Medical Microbiology. 2006; 17(4):101-106.
9Op Cit 15.
10Hamilton AC. The climate of the East Usambaras. In: Hamilton AC, Bensted-Smith R (Eds). Forest conservation in the East Usambara Mountains, Tanzania. IUCN, Gland. 1989:97-107.
11University Corporation for Atmospheric Research (UCAR). Climate Change and Vector Borne Disease. 2019. Retrieved from: https://scied.ucar.edu/longcontent/climate-change-and-vector-borne-disease on 30/8/19.