Climate change and the transmission of tropical infectious diseases

¶ … Global Warming and the Spread of Disease

Climate change is a natural phenomenon, but man\'s interferences with the natural processes has resulted in an accelerated worming over the last 1,000 years (Dahlman and Renwick 92). This has resulted in climate changes, for example, warm mid-latitude climates which had less rainfall and lower temperatures compared to tropical climates (Dahlman and Renwick 83), are seeing temperature increases which also raise the rate of precipitation. Likewise, even the Antarctica is warming (Dahlman and Renwick 95). This has numerous impacts, one is the increase spread of infectious diseases (Altizer et al. 514).

Disease is spread by living organisms. Living organisms may be adaptive, but their survival is constrained by their environment; if the temperature is incorrect, or the humidity is not suitable, the disease causing organism may die. It is not only the direct impact of environmental changes which may impact on the ability of disease to spread, in many cases the use of an agent is requited; as seen with malaria (Worland 1). Therefore, climatic changes which impact on host organisms may influence the spread of disease. Importantly, while this is often considered in the context of human disease, it is not limited to only the mankind, but the entire animal and plant kingdoms (Altizer et al. 514).

There are many diseases which have long plagued tropical areas; dengue fever, cholera, malaria, and more recently the zika virus are all sensitive to temperature changes (Worland 1; Chan 1). These examples require relativity high temperature levels as they are transmitted by mosquitoes (Chan 1). The World Health Organization states that these diseases can only be transmitted in areas where there is a temperature of between 61 and 100 degrees Fahrenheit, with greater effectiveness the closer the temperature gets to 86 degrees (Worland 1). This indicates that there is a potential problem where temperatures are rising, as global warming is increasing the range and scope of areas that provides a suitable environment for the mosquitos. The situation is also exacerbated by the way the climate change pattern which are increasing temperatures may also increase precipitation in areas, such as mid-latitude areas; increased still bodies of water, which are caused and sustained by rain, also support the presence of mosquitos, facilitating their reproduction. This results in a greater potential for diseases which were once severely constrained by weather condition, to spread outwards and impact more areas (Altizer et al. 514).

It may be argued that the impact will not be equally great in all areas, wealthy areas, such as the U.S. will be more prepared to deal with the spread of the mosquitos, compared to poorer areas, which have fewer resources (Worland 1). However, even if areas are prepared, it does not stop the potential spread. For example, in 2016 the CDC has reported a total of 139 cases of the zika virus being contracted locally in Florida (CDC 1).

Altizer et al. (514) also note the spread is not impacted only by the infection agent, but also the immune response of the potential infected party. Firstly, new diseases are entering areas where there is little natural immunity in the local population due to lack of exposure. In addition, warmer temporaries have been found to lower the effectiveness of host immunity (Altizer et al. 514). The example of mosquito borne illnesses is well documented, but the concept can be expended to many other pathogens which are spreading into new areas; generally warmer climates are able to support more infections pathogens (Altizer et al. 514).