Climate change-driven migrations worsen infectious diseases in vulnerable regions

By Priyanjana Pramanik, MSc.Reviewed by Susha Cheriyedath, M.Sc.Aug 1 2024

In a recent perspective article published in the journal Nature Climate Change, researchers explored the complex relationship between migrations caused by climate change and the increased burden of infectious diseases.

The authors emphasized how factors like pathogen spread, overcrowding, and closer proximity to disease vectors exacerbate health risks.

They pointed out that the countries most affected by these health consequences are often the least responsible for climate change, highlighting the urgent need for further studies to provide robust evidence and develop targeted interventions.

Perspective: Impacts of climate change-related human migration on infectious diseases. Image Credit: ArteIndex / Shutterstock

Climate change and infectious disease risks

Climate change has been linked to heightened risks of transmission of infectious diseases, driven by factors such as internally displaced persons and changing land use patterns.

A comprehensive review has revealed that over 50% of known infectious diseases could be exacerbated by climate hazards, while several reports have established pathways through which climate change increases disease transmission.

Changes in climatic and land use patterns are increasing the frequency of events where zoonotic viruses are transmitted and, thus, the probability of them spilling over into human populations.

Other pathways described by researchers include the increase in suitability for vectors of disease and faster transmission of pathogens at warmer temperatures. Extreme weather events also disrupt health systems, leading to overcrowding and increased disease burden.

Despite the growing evidence, the interplay between climate change, migration, and health remains underexplored, with most research focusing on short-term impacts. Vulnerable regions, particularly in Africa and Asia, bear the greatest burden of these health challenges despite contributing minimally to greenhouse gas emissions.

This imbalance underscores the need for region-specific adaptations to tackle these multifaceted crises effectively.

Drivers of climate change-related migration

Climate change is reshaping global habitability, with severe impacts such as sea-level rise in Bangladesh potentially displacing millions by 2060. Migration can serve as an adaptation strategy, though it is often a last resort due to factors like socioeconomic status and political instability.

Fast-onset events, such as hurricanes, cause immediate displacements, whereas slow-onset events, like rising temperatures, lead to long-term migrations, especially in regions reliant on agriculture. The journal paper specific examples, such as the impact of Hurricane Maria in Puerto Rico and the 2011 drought in the Horn of Africa, to illustrate these drivers.

High-income countries generally have greater resilience to climate impacts than low—and middle-income countries (LMICs), which are at higher risk of health issues related to these migrations.

There is a critical need for targeted studies to understand the health impacts in LMICs for effective mitigation strategies.

Impact of migrations on infectious diseases

Climate change-related migrations influence the dynamics of infectious disease through forced displacements, which lead to overcrowding, inadequate sanitation, and heightened risks of diseases like malaria, cholera, and human immunodeficiency virus (HIV).

Increased proximity to animal vectors, food insecurity, and urbanization further elevate the risk of zoonotic spillovers and disease outbreaks in new regions. Displaced populations are often exposed to diseases they lack immunity against, while returning migrants can introduce pathogens to non-endemic areas.

Additionally, habitat loss and increased human-wildlife interactions due to land-use changes exacerbate disease transmission. The paper highlights the increased risks associated with temporary shelters and changes in wildlife behavior due to habitat loss. Addressing these issues requires targeted interventions in housing, sanitation, and disease surveillance.

Strategies for adaptation

Short-term interventions for climate-related threats focus on immediate responses, such as evacuations and the provision of essential services during extreme weather events. While these measures have reduced mortality rates, they are inadequate as such events become more frequent.

Long-term strategies, including mitigation and adaptation, are crucial. Mitigation efforts aim to reduce the consequences of climate change, while adaptation strategies enhance human resilience. Examples include strengthening healthcare infrastructure, monitoring for disease outbreaks, and developing climate-resilient cities like Fukuoka and China's Sponge City.  

Preparedness is vital, particularly in regions historically less affected by climate events but now increasingly vulnerable. The paper emphasizes the importance of building climate-resilient healthcare facilities and integrating sustainable practices to manage health consequences.

Conclusions

Despite mounting evidence that climate change is linked to the spread of infectious diseases, the current understanding of the interrelationships between climate change, human displacement or migration, and the transmission of infectious diseases is limited.

Climate disasters will lead to short-term displacements as well as long-term migrations, significantly influencing the burden and spread of infectious diseases.

Weather-related events like floods and storms have caused most large-scale displacements within countries in recent years, exacerbating disease spread through increased spillovers, overcrowding, and limited access to healthcare.

The paper identifies knowledge gaps in evaluating adaptation strategies and stresses the need for comprehensive research to combat these health challenges effectively.

This calls for focused research on these intersecting issues, especially in LMICs, which often are less prepared for climate challenges and experience disproportionately higher levels of displacement.

Further comprehensive research on mitigation and adaptation strategies is essential to effectively combat the health challenges that climate change poses.