Climate change is perhaps the greatest threat to human health. In a warming world, with changing and unpredictable weather patterns, its effects are all around us.

In 2022, Pakistan experienced the worst floods in the country’s history, placing much of the country under water and giving way to a fivefold increase in the country’s rate of malaria transmission.

 Earlier this year, Brazil declared a state of emergency as its national healthcare system buckled under the pressures of an outbreak of dengue, a neglected tropical disease (NTD) carried by mosquitoes. 

Cases continue to rise and the outbreak shows no sign of stopping. But Brazil is not alone. Over the past two decades, dengue cases have increased eightfold, with the mosquitoes that carry it thriving in areas where climate change has made temperatures higher and precipitation more abundant.

Despite these daily reminders, there is much we do not understand about the impact climate change is exacting on malaria and NTDs, both of which disproportionately impact low-income countries (LICs). An ongoing effort to rid the world of these debilitating diseases by understanding the impacts of climate change isn’t just important – it’s imperative.

Evidence gaps

 An unprecedented scoping review highlights significant gaps in evidence. It was conducted by the World Health Organization (WHO) Task Team on Climate Change, NTDs and Malaria, in partnership with Reaching the Last Mile, a portfolio of global health initiatives driven by the philanthropy of United Arab Emirates President Sheikh Mohamed bin Zayed Al Nahyan.

Spanning 42,693 articles from the past decade, the review correlates climate fluctuations with changing disease patterns, confirming that changing temperature and rainfall patterns will shift the transmission windows and geographies of malaria, dengue and chikungunya.

The research also reveals that, as our planet warms, the poorest and most vulnerable communities are poised to suffer even more. It also highlights that our research agenda is imbalanced, with studies historically focused on where disease burden is low and access to quality healthcare is high.

This is not merely a health issue but a profound injustice that compounds vulnerabilities among those least equipped to bear them.

Given the complex and nonlinear ways these diseases interact with changing climates, the importance of closing our gap in understanding is clear. As we already see with dengue in Brazil – and will continue to see in other areas for years to come – diseases are being transmitted faster and farther than before as vectors like mosquitoes expand to regions previously unexposed to these diseases.

This could lead to new outbreaks in populations without any natural resistance or existing health infrastructure to manage such diseases. It’s only further complicated by increased displacement and migration as a result of a changing climate.

Adaptation and mitigation

Despite the clear risk, our understanding of how to mitigate or adapt to the impact of climate change on malaria and NTDs is limited. Adaptation and mitigation strategies were discussed in only a fraction of the scientific literature reviewed by the WHO Task Team. This needs to change.  

A new research agenda is crucial to inform evidence-based adaptation and mitigation strategies.

In a world acutely aware of the effects of climate change, this all matters immensely if we are to preserve our gains and investments. As global citizens and stakeholders in global health – whether policymakers or researchers, NGOs, funders, or community leaders— we must adapt our strategies and responses not just to the diseases as we’ve known them, but to how they will evolve in a changing climate.

This will require innovative approaches to our public health interventions as dynamic as the challenges they aim to counter.

 We must build resilient, climate-responsive health systems, surveillance programs and intervention strategies to mitigate against or adapt to the immediate-short-term and long-term effects of climate change on malaria and NTDs.

We must ensure communities have the resources to respond to health threats in the context of real-time challenges and changing dynamics, like rising temperatures, extended rainy seasons or drought – particularly in the ‘last mile.’

This will require us to reimagine and invest in a new research agenda driven by scientists on the frontlines of this climate-vector-borne disease nexus aimed at protecting those most vulnerable to its impact.

Stronger action on the ground

We need a committed, global push for research that not only tracks disease trends but actively explores robust intervention strategies that consider the full spectrum of climate impacts. 

This includes a holistic approach to hazard assessment, driven by research that examines the links between hazards, vulnerability and exposure so we can more accurately project the potential effects of climate change on malaria and NTDs.

The climate crisis will only continue to put strain and pressure on already fragile health systems, diverting precious resources from other budget lines, including malaria and NTDs. With more evidence, we can break this cycle and protect the resources needed for disease response.

Last week, the World Health Assembly adopted the WHO’s 14th Global Programme of Work, which prioritises the climate-health nexus. Member states also adopted the strongest resolution yet on climate change and health. 

Now we need to see even stronger action on the ground. Let’s marshal our collective resources and ingenuity to ensure that our responses are as adaptable as the diseases we’re striving to overcome.

The time to act is now. This new WHO paper is not just a summary of data; it’s a call to action. It’s a directive for all of us involved in the fight against malaria and NTDs to look beyond our current horizons and plan for a future where climate change reshapes the landscape of global health. For the sake of the millions at risk, we must heed this call and act swiftly and decisively.

It’s no small challenge, but one that we can overcome together.

Dr Ibrahima Socé Fall is the Director of WHO’s Global NTD Programme.

Dr Michael Adelkunle Charles is CEO of the RBM Partnership to End Malaria.

Image Credits: Yoshi Shimizu, Billy Miaron/ WHO.