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Climate Change Can Increase Risks of Infectious Diseases and Other Health Concerns

Headshots of three smiling scientists
Danielle Buttke (left), Jeff Dukes and Kacey Ernst discussed the health impacts of climate change in a Facebook Live event on Earth Day. | Photos courtesy of pictured

Climate change is already affecting the health of humans and animals, driving increases in infectious diseases and heat-induced illnesses, according to several experts on climate change and epidemiology.

Hosted by the AAAS Center for Public Engagement with Science and Technology, the April 22 Facebook Live event “Looking Ahead on Earth Day: How Climate Affects our Health – and What You Can Do” brought together several experts to address the intersection of climate change and health and to share steps that communities and individuals can take to mitigate negative effects and build resilience.

Climate change could affect outbreaks of zoonotic diseases, illnesses such as COVID-19 that can jump from animals to humans and vice versa, said Danielle Buttke, a veterinary epidemiologist for the National Park Service and coordinator of its One Health initiative to improve the health of people, animals and the environment. Buttke was a 2017-2018 fellow with the AAAS Leshner Leadership Institute, which brings together scientists for intensive training on science communication and public engagement regarding specific topics.

“When you have a healthy ecosystem, it helps to regulate disease,” said Buttke. Yet when the ecosystem is affected by issues such as warming temperatures or a loss of predators, diseases can spread more easily.

Non-native plague, for instance, is impacting populations of wildlife for which experts had not put into place prevention measures.

“This, of course, presents unique opportunities for disease to spill over into humans,” Buttke said.

Human impacts on wildlife and the environment are driving many outbreaks of infectious disease in animals, Buttke said. If human activities destroy a habitat, animals might then migrate into new areas, putting into close proximity groups of animals that had never before connected. Live animal markets also bring together different species – including humans – from different natural habitats, said Buttke.

“You have the potential for new diseases to hop into new species that they had never interacted with previously,” said Buttke.

Stressful situations can exacerbate outbreaks, too. Much in the way that a person might catch a cold more easily when they are stressed, animals are also more susceptible to disease while under stress. If animals are stressed – whether by environmental factors like higher temperatures, drought or being caged at a market – they can experience higher disease burdens, an increased chance of shedding viruses and a higher exposure to new viruses, said Buttke.

Climate change impacts also are affecting the transmission of vector-borne diseases, such as malaria, West Nile virus and Lyme disease, which are spread by mosquitos, ticks and other vectors.

“There’s a really tight link between environmental conditions and vectors of disease. It’s complex but overall in many locations, we expect that we’re going to see increasing vector-borne diseases,” said Kacey Ernst, associate professor and program director of epidemiology at the University of Arizona. Ernst also was a Leshner Leadership Institute fellow in 2017-2018.

Temperature changes and precipitation levels in a location can extend mosquito season, and mosquito populations can persist through shorter, milder winters, said Ernst. Evidence also shows that changes in climate allow animals like ticks to move into new geographic areas, which is one factor that has spurred an increase in Lyme disease in the United States, Ernst said.

Increasing temperatures are resulting in longer, hotter and more frequent heatwaves, which in turn cause health effects like more cases of heatstroke, said Jeff Dukes, professor of forestry and natural resources and biological sciences at Purdue University and director of the Purdue Climate Change Research Center. Dukes was a 2016-2017 fellow with the Leshner Leadership Institute.

The panelists discussed what communities can do to mitigate the impacts of climate change and its ensuing health effects, including following in the footsteps of the locations featured in AAAS’ How We Respond project, which highlights 18 communities that are using scientific information to mitigate and adapt to climate change impacts at a local or regional level.

Marquette, Michigan
Marquette, Michigan, is among the communities that have consulted scientists and community members to develop a plan to protect its residents from the impacts of climate change. | yooperann/Flickr CC BY-NC-ND 2.0

“Scientists report higher temperatures, greater flooding and increased water- and vector-borne illnesses will pose rising threats to residents in Michigan and the Great Lakes area,” the report says. To respond, policymakers in Marquette, Michigan, have worked with scientists and community members to develop a plan for responding to climate change and the impacts on the health of the city’s residents, said Emily Therese Cloyd, director of the AAAS Center for Public Engagement with Science & Technology and the event’s moderator.

Another important strategy for communities is boosting awareness of the effects of climate change and of the resources available to them, said Ernst.

“Trying to get an informed community is one of the best strategies that we can have moving forward, because we can’t just rely on outside entities and outside organizations. We need to be building this resilience within our own populations from within,” Ernst said.

Communities also must recognize that the effects of climate change on health will be different in different places and understand which vulnerable populations will experience the most serious health effects from climate change, experts said. Populations currently being hit hard by COVID-19 – including elderly people, people with existing health conditions and communities with fewer resources – are similar to those that experts anticipate will be disproportionately affected by climate change and the resulting health impacts, Dukes said.

Speakers also identified steps that individuals can take, such as contributing to vector- and disease-tracking through community-engaged science. People can contribute to mosquito surveillance on platforms like iNaturalist or NASA’s GLOBE Mosquito Project, said Ernst. They can also contribute to “syndromic surveillance” projects, which allow individuals to report their disease symptoms, such as the Kidenga project that Ernst runs.

Panelists also encouraged individuals to share the impacts of climate change within their communities, listen to others’ concerns and make visible their own efforts to reduce their carbon footprint, which can encourage others to follow in their footsteps.

Said Buttke, “What you do and how visible your actions are make a huge difference.”