The Effect of Climate Change on Disease

Climate change is predicted to cause unprecedented increases in both the severity and frequency of extreme weather events, but the effects are likely to radiate much further. Secondary to these risks, a shifting climate will influence the pattern of health and reshape the burden of disease – especially those transmitted by mosquitoes and ticks.

Malaria and Dengue Fever

Since the geographical distribution of insect-borne diseases is dependent on the environment, climate change will affect the spread of illnesses such as Malaria and Dengue fever. Mosquitoes thrive in warm, humid conditions with high rainfall and so coastal areas suffering from climate change are expected to become increasingly hospitable to disease carriers such as Anopheles and Plasmodium vivax.

 projected malaria.png

As illustrated on the map, Malaria is predicted to expand into new coastal regions, and since coastal areas generally feature higher population density, this is likely to increase the global burden of this disease.

The effect of climate change will affect insect-borne diseases via other subtler means, too. In a warmer environment, the Dengue virus matures at a faster rate, and so the infected mosquitoes have a greater and longer capacity to spread the disease vector.

12123.png

Lyme Disease

Along with the geographical expansion of mosquito-borne ailments, the projected shift in climate is predicted to influence the spread of diseases via ticks. Warmer winter seasons coupled with longer dry periods allow ticks to survive longer, and helps them mature faster. This means that ticks have a greater infection window, which is likely to exacerbate the spread of Lyme disease.

In the United States of America, the population of ticks in Missouri is limited by the cold, wet winters. However, climate change threatens to impose warmer winters and therefore allow the migration of ticks into central America. With larger regions becoming more hospitable to disease carriers, it is likely that the impacts of Lyme disease will begin to spread through the inland population – as illustrated in the figure below.

Tick HAbitat.png

 

The primary impacts of climate change on the environment have been well established, yet secondary risks such as disease patterns are often overlooked and ignored. It is essential that we recognise and investigate these secondary risks so that we can best prepare for the possible spread of disease into the future. Inaction and ignorance is not a neutral stance – refusing to acknowledge the changing landscape of disease will put individuals at harm and entire populations at risk.

 

 

References

1.  McKibben B.  Climate Change Impacts in the United States: The Third National Climate Assessment. 2014 New York Review 1755 Broadway, 5th Floor, New York, NY 10019 USA.

2.  Brownstein JS, Holford TR, Fish D. Effect of climate change on Lyme disease risk in North America. EcoHealth. 2005;2: 38-46

3.  Research UCfA. Climate Change and Vector-Borne Disease. 2011 [cited 2017 22/02/17]. Available from: https://scied.ucar.edu/longcontent/climate-change-and-vector-borne-disease

4.  Slenning BD. Global climate change and implications for disease emergence. Veterinary Pathology Online. 2010;47: 28-33

5.  Naish S, Dale P, Mackenzie JS, McBride J, Mengersen K, Tong S. Climate change and dengue: a critical and systematic review of quantitative modelling approaches. BMC Infect Dis. 2014; 167

6.  Githeko AK, Lindsay SW, Confalonieri UE, Patz JA. Climate change and vector-borne diseases: a regional analysis. Bull W H O. 2000;78: 1136-1147

7.  Rodó X, Pascual M, Doblas-Reyes FJ, Gershunov A, Stone DA, Giorgi F, et al. Climate change and infectious diseases: Can we meet the needs for better prediction? Clim Change. 2013;118: 625-640

8.  Wu X, Lu Y, Zhou S, Chen L, Xu B. Impact of climate change on human infectious diseases: Empirical evidence and human adaptation. Environ Int. 2016;86: 14-23

9.  Campbell-Lendrum D, Manga L, Bagayoko M, Sommerfeld J. Climate change and vector-borne diseases: what are the implications for public health research and policy? Phil. Trans. R. Soc. B. 2015;370: 13-55

10.  Bousema T, Drakeley C. Epidemiology and infectivity of Plasmodium falciparum and Plasmodium vivax gametocytes in relation to malaria control and elimination. Clin Microbiol Rev. 2011;24:377-410

11.  Wu X, Lu Y, Zhou S, Chen L, Xu B. Impact of climate change on human infectious diseases: Empirical evidence and human adaptation. Environ Int. 2016;86: 14-23.

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