Climate Change as a Public Health Issue

by Shannon O’Neill

The World Health Organization (WHO) estimates that roughly half of the world’s population is at risk of infection by vector-borne disease. Furthermore, vector-borne diseases are responsible for one-sixth of illness and disability throughout the world, killing at least one million people each year. Vector-borne diseases tend to highlight socioeconomics differences and problems, as they increase health inequalities, with developing countries having a 300 times greater mortality rate from them. These countries do not have the resources for preventative care or to manage outbreaks. Additionally, vector-borne diseases tend to paralyze health systems and substantially decrease tourism. Though some efforts to control vector-borne diseases have been quite successful, these diseases still pose a major threat to the world as re-emergence becomes more likely owing to greater organism drug resistance and other changing environmental factors.

Climate change is believed generally to increase the incidence of vector-borne disease, because warmer temperatures often increase the geographical distribution of vectors and increase pathogen success. Furthermore, increased precipitation contributes to the success of vectors that have an aquatic component to their lifecycle. Climate change also affects social and demographic conditions, which can indirectly increase the incidence of vector-borne disease. For example, dams and other water transport projects can become ideal breeding spots for mosquitoes, arguably the most prominent vector of vector-borne diseases. Many models have been formulated to determine the effects of climate change on vector-borne disease, with the biggest takeaway being that these diseases are more successful than they otherwise would have been without climate change, even though such interactions between climate, vectors, and pathogens, are very complex and mostly poorly understood. Many studies have focused on the diseases themselves, to determine if they have changed in reaction to climate change. Such studies, however, are difficult to carry out, because of their long-term data requirements. Nevertheless, results have shown that climate change has increased the incidence of disease in some areas.

Another method that has been used is assessing potential future outbreaks are climate projection models, used to determine areas that are likely to be the most susceptible to future outbreaks. These models have largely focused on temperatures, usually ignoring precipitation rates which is often as important in vector-borne disease success.

Though research and policy is headed in the right direction in order to take care of potential outbreaks, only fractions of the potential problems and costs have been realized, and therefore more information and research in this field should be continued.

Campbell-Lendrum, D., Manga, Lucien, Bagayoko, Magaran, Sommerfeld, Johannes. 2015. Climate change and vector borne diseases: what are the implications for public health research and policy? Phil. Trans. R. Soc. B 370: 20130552.


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