Why climate change could lead to more infectious diseases

Most infectious diseases in humans start in another animal. Three out of four new or emerging diseases in humans are caused by animals, as are six out of 10 infectious diseases known to infect humans, according to the CDC.

The reason for this is simple: As we interact with our environment and all the organisms that live in it, we are bound to be exposed to zoonotic diseases – zoonotic diseases. animals to people – whether we like it or not. Unfortunately, with climate change ravaging our planet, humanity is potentially exposed to new diseases.

In a new study published Thursday in the journal Nature, researchers predict that climate change will shake up where animals live, fueling the exchange of more infectious viruses than ever before — and all in dangerous proximity to humans. Incredibly, this impending global health crisis could be happening — and potentially happening even as we manage to keep global warming down to 2 degrees Celsius, above which we will enter an unstable world of climate change.

“This study takes an important first step in building a model to measure a hypothesis: Climate change will promote species dispersal as they track the most suitable climate conditions, ” Erin Mordecai, an infectious disease biologist at Stanford University who was not involved in the study, told The Daily Beast in an email. “This dispersal will lead to new contacts between species that have never been in contact with each other in the wild, leading to potential pathogen exchange.”

For many years, scientists studying climate change have known that storms, widespread floods and droughts caused by an erratic climate are responsible for waterborne diseases and diarrhea in many parts of the world. vulnerable areas of the world, Dr. Aaron Bernstein, a pediatrician and public health researcher at the Harvard TH Chan School of Public Health who was not involved in the new study, told The Daily Beast.

“There is some evidence that warming may contribute to more malaria in places like the East African highlands and the Andes in South America because mosquitoes can live higher up the slopes,” says Bernstein. mountains,” said Bernstein. “But there have been and continue to be concerns about how climate change might affect the movement of pathogens from one animal to another or from animals to humans.”

We don’t have a clear picture of how thousands of species of mammals seeking a cooler climate will affect global health. There are about 10,000 viruses in nature that can infect humans as far as we know. Thomas Gillespie, an ecologist and epidemiologist at Emory University, who was not involved in the study, told The Daily Beast, most of them are quietly hiding among wild mammals and have most likely will jump to humans.

To understand what the future holds, scientists at Georgetown University and other research institutions have spent the past five years testing various computer simulations to see what happens when the The land use and communities of a species change with changing climate. And what they discovered was astounding: By 2070, there will be 4,000 times greater numbers of viruses that can be transmitted between species. That means wild mammal species will share more viruses than ever before. Above all, these virus transmission hotspots are located near human communities, especially in tropical regions such as Southeast Asia and East Africa.

“We [found] Disproportionately these are densely populated areas such as many urban areas and underdeveloped areas will experience these novel encounters that will be driven by past climate change. ,” said Gregory Albery, an infectious disease ecologist at Georgetown University and co-author of the new research book, in a statement. “And it also happens in much more arable land than would be expected in all these types of wilderness. These are obviously places close to people and livestock. “

This forecast doesn’t look at whether animal-to-human transmission of the virus will spike in tandem, but the researchers say we could most likely see more outbreaks of familiar diseases like Ebola. , influenza and COVID-19, and outbreaks from new and unknown viral diseases.

Colin Carlson, an environmental scientist at Georgetown University and co-author of the new study, said: “Climate change is creating a myriad of hotspots for future risk of zoonotic transmission or danger. The chance of transmission from animals is now right in our backyard.”

While the new study is a much-needed wake-up call, experts like Mordecai and Gillespie say more field work is needed because the nature of infectious disease is complex and there are many factors — like human trade, mobility and other animals such as insects and birds — tied to climate change. But there is hope that this research will inspire humanity to take action to prevent the impending doom of climate change.

“[This paper] provides an important impetus for reducing greenhouse gas emissions and mitigating climate change: It is one avenue by which climate change can affect human and animal health,” Mordecai said. “Policymakers should also prioritize surveillance for pathogens, particularly where wildlife, humans and livestock interact, as well as preserving intact ecosystems that support populations of healthy animals and ecosystem services.”