Newswise — WASHINGTON — Based on data that span the past 120 years, scientists at Georgetown University Medical Center have found that the mosquitoes responsible for transmitting malaria in Africa are spreading deeper into southern Africa and to higher elevations than previously recorded. The researchers estimate that Anopheles mosquito populations in sub-Saharan Africa have gained an average of 6.5 meters (21 feet) of elevation per year, and the southern limits of their ranges moved south of the equator by 4.7 kilometers (nearly 3 miles) per year.
The study appeared February 15, 2023, in Biology Letters.
“This is exactly what we would expect to see if climate change is helping these species reach colder parts of the continent,” says Colin Carlson, PhD, an assistant research professor at the Center for Global Health Science and Security at Georgetown University Medical Center and lead author of the study. “If mosquitoes are spreading into these areas for the first time, it might help explain some recent changes in malaria transmission that have otherwise been hard to trace back to climate.”
The world is at least 1.2 degrees Celsius (about 2 degrees Fahrenheit) warmer than in the pre-industrial period. In 2011, scientists estimated that earth-bound species were moving uphill at a rate of 1.1 meters per year, and to more polar latitudes at 1.7 kilometers per year, making the movement of mosquitoes a relatively fast shift by comparison.
The investigators focused on mosquitoes in the genus Anopheles both because of their ability to spread malaria, and because of a unique historical dataset tracking their movements. Carlson notes that other species are probably moving in similar ways, but that future research efforts will have to get a sense of what’s happening in different regions or with different diseases to gain the most comprehensive picture possible.
“We tend to assume that these shifts are happening all around us, but the evidence base is fairly limited,” says Carlson. “If we’re reimagining bio-surveillance for life on a hotter planet, a big part of that is going to have to be keeping an eye on animal movement.”
Carlson notes that his team has been learning a lot about long-term biodiversity change thanks to deep historical public health records. “We know so little about how climate change is affecting invertebrate biodiversity. Public health is giving us a rare window into how some insects might be thriving in a changing climate—even if it’s bad news for humans.”
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All study authors are at Georgetown University and include Colin Carlson, Ellen Bannon, Emily Mendenhall, Timothy Newfield and Shweta Bansal.
The authors report having no personal financial interests related to the study. No original data was used in this study as the Anopheles dataset is freely available from previously published research.
About Georgetown University Medical Center
As a top academic health and science center, Georgetown University Medical Center provides, in a synergistic fashion, excellence in education — training physicians, nurses, health administrators and other health professionals, as well as biomedical scientists — and cutting-edge interdisciplinary research collaboration, enhancing our basic science and translational biomedical research capacity in order to improve human health. Patient care, clinical research and education is conducted with our academic health system partner, MedStar Health. GUMC’s mission is carried out with a strong emphasis on social justice and a dedication to the Catholic, Jesuit principle of cura personalis -- or “care of the whole person.” GUMC comprises the School of Medicine, the School of Nursing, School of Health, Biomedical Graduate Education, and Georgetown Lombardi Comprehensive Cancer Center. Designated by the Carnegie Foundation as a doctoral university with "very high research activity,” Georgetown is home to a Clinical and Translational Science Award from the National Institutes of Health, and a Comprehensive Cancer Center designation from the National Cancer Institute. Connect with GUMC on Facebook (Facebook.com/GUMCUpdate) and on Twitter (@gumedcenter).
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