Why infectious diseases are spreading — and what we can do about it
As global temperatures rise, malaria and other infectious diseases are on the move. Dr. Jennifer Gardy, a senior scientist with the Bill and Melinda Gates Foundation and UBC alumnus, explains why this poses a major threat to global health— and why we need to act now, together.
As a senior scientist with the Bill & Melinda Gates Foundation, I strongly believe that malaria eradication — zero malaria worldwide — is possible within a generation. I also know that it’s not going to be an easy trajectory. One of the factors that complicates our work is climate change.
Rising global temperatures aren’t just a challenge for those of us working to eradicate malaria — they’re also one of the most disruptive threats the global health community has ever encountered. How we choose to respond today will have enormous consequences for the world our children and grandchildren will live in tomorrow.
The reality is that climate-related disruptions, from floods to cyclones to food insecurity, are intimately linked to global health. They directly influence everything from a population’s vulnerability to disease through to disease ecology, epidemiology and transmission, and ultimately to our ability to effectively respond to infectious threats.
As I wrote this from my home office in Chicago, my city was experiencing the worst air quality in the world due to smoke from Quebec’s wildfires, and people with respiratory conditions were being asked to stay indoors. That may be possible for a privileged few, but workers whose jobs keep them outdoors are risking their health in order to preserve their economic livelihoods.
Meanwhile, the World Meteorological Centre has declared July 2023 the hottest month on record, with many places across the globe routinely exceeding temperatures of 40C. In the immediate term, heat like this is profoundly dangerous for anyone going outside or working in poorly ventilated indoor environments; in the medium- and longer terms, rising temperatures are changing disease ecology in myriad ways.
Many infectious threats can be effectively countered with vaccines, robust testing and treatment programs, and programs aimed at preventing spillovers of disease from animal into human populations.
Warming temperatures extend disease transmission seasons, meaning that viruses like dengue that were once seasonal can now spread throughout the winter months in certain geographies. Melting snowpacks and rising ocean temperatures have unleashed old strains of species such as anthrax and Vibrio, and have created the ideal conditions for harmful algal blooms to grow, rendering our coastal waters and our seafood supplies dangerous.
Droughts force insects and wild animals to gather around any available water source, putting them in close contact with human populations and seeding disease spillover events, from West Nile virus to hemorrhagic fevers like Ebola.
At the other end of the spectrum, floods result in wastewater overflow and increased direct and foodborne transmission of a range of diseases, from cholera to typhoid. And, as both of these types of climate emergencies impact our ability to grow crops, food insecurity and population displacement put large portions of our world’s most vulnerable populations at even greater risk for communicable and non-communicable diseases alike.
In my own work on malaria, I see these threats seemingly converge into a perfect storm. Changes in temperature, humidity, and rainfall are altering the malaria map and bringing the mosquito vector back to places where the disease had previously been eliminated. In fact, the United States recently reported its first locally acquired malaria infections in decades.
In other parts of the world, the malaria transmission season is growing longer with prolonged rainy seasons. Higher rates of malaria infection place a heavier burden on health care — disrupting our ability to deliver basic health services, often where they are needed most. This, in turn, has a profound impact on our ability to prevent, test for, and treat malaria, creating an ever-tightening cycle of infection and poor health.
The reality we face as a global health community is that our planet’s temperature will continue to rise for several decades, even if we were to completely eliminate greenhouse gas emissions today. Our children and our children’s children will still be facing many of the climate-associated infectious disease threats outlined above — that is, unless we take collective action to mitigate these threats now.
What does this action look like? Luckily, for many diseases, we already know what works. Malaria is preventable and treatable. Through intensive mosquito control efforts and use of other prevention tools, from bed nets to preventive treatments, many countries completely eliminated malaria from within their borders in the late 1990s.
Similarly, many other infectious threats can be effectively countered with vaccines, robust testing and treatment programs, and programs aimed at preventing spillovers of disease from animal into human populations.
As the global health community, we must double down on disease control efforts and work towards reducing the incidence of malaria and other climate-sensitive threats today so that we’re better prepared for outbreaks and resurgences of disease in the future.
How we choose to respond today will have enormous consequences for the world our children and grandchildren will live in tomorrow.
Disease control will require smarter, more strategic use of our current tools, and it will also require new ones. For example: innovative and efficient prevention tools like a single injection of monoclonal antibodies that can be delivered in challenging settings and offers a full season’s worth of malaria protection, or self-replicating RNA vaccines that have the potential to be manufactured more quickly and in larger quantities than traditional vaccines.
To make these and other interventions sustainable, we need to build and strengthen our health systems at home and around the world, so they can withstand disruption from climate and other events. Most importantly, we need to ensure that the most vulnerable people have access to health services, so they can live longer, healthier lives.
Ultimately, keeping the global spread of infectious disease in check will be a multidisciplinary effort, engaging researchers, academia, governments, health authorities and professionals across domains from health to social sciences to engineering to entomology. It will unfold at all levels — from global, national and regional policy decisions to hyper-local delivery of life-saving interventions. And none of it will be possible unless it’s driven from the ground up, engaging local communities and understanding how their lived experiences can inform better disease control strategies.
At the Bill & Melinda Gates Foundation, we are committed to accelerating malaria eradication in the face of the climate crisis. This is a necessary but winnable battle in what we know will be a long-term war against climate change, and it’s a battle that will take collaboration between organizations like the Foundation and the brightest minds from academia.
My own journey at UBC — as an undergraduate student curious about microbiology, then a postdoctoral fellow exploring the intersection of computational biology and immunology, and ultimately a faculty member developing innovative new approaches to public health epidemiology — shows just how much a community like UBC can shape the next generation of global health and climate science leaders.
UBC inspires its students to explore new areas and follow their interests, particularly through innovative and interdisciplinary programs. It nurtures talent and shows students how their work can have real-world impact. And it recruits world-class talent whose bright ideas will become the innovations that in the future will help us secure a healthy and resilient future for our world’s population.
Dr. Jennifer Gardy (BSc’00)
Deputy Director, Surveillance, Data, and Epidemiology
Bill and Melinda Gates Foundation
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