On Earth Day, researchers note that climate change is impacting the areas in which infectious ... [+]
Climate change may not only lead to rising ocean levels and more disruptive weather systems. On this Earth Day, researchers also warn that climate change may lead to new patterns of infectious diseases. As our planet warms, the ranges of pathogens may change. The result? Diseases typically thought to be limited to the tropics may become commonplace in other regions of the world, including the United States.
The trends are already troubling. Nearly 5 million suspected cases of dengue have been reported thus far in 2024, according to data provided by the Pan American Health Organization. This represents a 448% increase for this period over the average of the past five years. Local transmission in the U.S. has been reported in Hawaii, Texas, Arizona, Florida and California, according to the CDC. In Puerto Rico, a public health emergency recently has been declared as the number of cases surges.
Certain pathogens, like dengue virus, Zika virus and the malarial parasite Plasmodium falciparum, are transmitted to humans via mosquitoes. As Earth warms, the locations of these vectors will change.
For example, researchers from Georgetown University investigated the historical range of mosquitoes that transmit malaria in Africa. In an article published in Biology Letters, they reported that the insect habitat gained elevation and extended south from the equator throughout the 20th century. Such changes almost certainly are continuing. As a result, malaria may spread to new regions.
Of course, the impact of climate change on infectious diseases is not limited to mosquito-transmitted illnesses like malaria and dengue. In some cases, the ranges of the pathogens themselves are changing.
Naegleria fowleri, perhaps better known as the brain-eating amoeba, typically is found in warm lakes and rivers. Human infections are very rare and historically have been geographically limited to the southern U.S. But recent evidence suggests that the range of this pathogen may be expanding northward, presumably because of increasing water temperatures.
Similarly, the range of Vibrio species, bacteria found in brackish waters and associated with gastrointestinal illnesses, also is expanding as coastal waters warm.
The news may seem bleak. Indeed, in one recent report, scientists argue that over half of all human infectious diseases may be impacted by climate change. But we can prepare ourselves. In an article recently published in The Journal of Infectious Diseases, Dr. Jan Semenza delineates the current problem and argues that, “Monitoring epidemic precursors of diseases can tackle some of these challenges through early warning systems.”
In other words, a robust, well-integrated global surveillance system will help us prepare for an evolving infectious disease landscape. Perhaps that should be our goal on this Earth Day.
