The Spread of Infectious Diseases and the Unexpected Costs of Climate Change

by Haley Richardson

Climate change: it’s something we hear about nearly every day whether it’s in class, on the news, or in casual conversation. While most people know that climate change is not a good thing, many are not aware of the specific implications of the changes in the earth’s temperature and atmosphere. One of the more major yet less regarded effects of climate change is how rising global temperatures can change the habitable range of a species. More specifically, infectious agents, as well as the organisms that carry them, can begin to populate areas of the world that they were not able to before, spreading disease to regions that were formerly too cold for them to survive.

Infectious agents, like all other biological entities, have specific environmental factors that determine where they can grow and reproduce at the fastest rate. Often, these environments tend to be hot areas with a high quantity of water or a humid atmosphere. As a result, the areas of the world with the most infectious diseases tend to be the tropics, particularly after monsoon season, which results in large amounts of rain. However, as global temperatures rise, the formerly hot, humid areas of the tropics may become too dry for many disease-carrying organisms to handle, causing them to migrate to more temperate zones. By contrast, regions formerly too cold to have these disease-carrying organisms will become warmer and more humid, allowing the range of the species to expand further north. Furthermore, large-scale extreme weather events such as El Niño, La Niña and others are already increasing in frequency, bringing with them new organisms with new diseases to colonize areas affected by these phenomena.

For example, the infection rate of the malaria virus is primarily attributed to the species that carries it: mosquitoes. Although many parts of the world contain mosquitoes, only a specific species of mosquitoes in the Anopheles genus can carry the malaria virus. Malaria-carrying Anopheles primarily live in sub-Saharan Africa, where the temperature and humidity of the region are ideal for the mosquito’s life cycle. However, as climate change causes global temperatures to rise, Sub-Saharan Africa is expected to become too arid for the mosquitoes to thrive, and so scientists are predicting that they will migrate as far north as Southern Europe.

The consequences of the spread of diseases like malaria could be astronomical, especially in less developed countries where access to health services and vaccinations are limited. Additionally, by migrating to previously uninhabited regions, the Anopheles mosquito would be spreading the malaria virus to populations that had not had a chance to build up an immunity to the disease, amplifying its effects. Other similarly transmitted diseases such as yellow fever, sleeping sickness and dengue fever, as well as bacterial infections such as cholera and Lyme disease, are also predicted to spread at a faster rate and into previously uninhabited areas as global temperatures rise. All of these diseases in their newly acquired ranges could spell disaster for many people worldwide, and in some areas they already have.
​
However, lest this article be all doom and gloom, there are several initiatives that the international community has proposed to manage the spreading of infectious diseases due to climate change. Besides the obvious solution of slowing down carbon emissions to decrease the rate of rising global temperatures, scientists and lawmakers alike have come up with systems to monitor the spread of infectious diseases to ensure that responses to outbreaks will be faster and more efficient than before. Institutions such as the Pacific ENSO Application Centre have developed early-warning systems that could detect extreme weather events that could lead to outbreaks of disease, allowing them to inform governments to prepare relief in advance and educate the public on disease prevention. Other institutions such as the World Health Organization actively provide relief to diseased-ravaged areas, and lobby governments to provide funds and support to affected regions. Furthermore, scientists around the globe are working to develop vaccines to the planet's most deadly diseases, as well as ways to mass produce them in the most cost-effective manner. Thus, as global climate change alters the environment (perhaps irreparably) at a frighteningly fast pace, we can at least hope that human progress will move even faster.