Populations of large wildlife are declining around the world, while zoonotic diseases (those transmitted from animals to humans) are on the rise.
A team of Smithsonian scientists and colleagues have discovered a possible link between the two. They found that in East Africa, the loss of large wildlife directly correlated with a significant increase in rodents, which often carry disease-causing bacteria dangerous to humans. The team's research is published in the Proceedings of the National Academy of Sciences, April 28.
Smithsonian scientists found that when large wildlife like zebras decline on the African savanna, either due to a decreasing population or human made barriers like roads and fences, it can a significant increase in rodents, which often carry disease-causing bacteria dangerous to humans.
"Our study shows us that ecosystem health, wildlife health and human health are all related," said Kristofer Helgen, curator of mammals at the Smithsonian's National Museum of Natural History and co-author of the research.
Large animals, such as elephants, giraffes, antelope and zebras, have a profound influence on their ecosystems by feeding on vast amounts of vegetation and compacting and disturbing soil. As populations of these large species decline, the ecosystems they once dominated change in many ways.
The team's main question was whether the loss of large wildlife influences the risk of people contracting diseases spread by rodents—a pressing question, as more than 60 percent of infectious human diseases are zoonotic.
"Understanding the linkages between biodiversity loss and zoonotic disease is important for both public health and nature conservation programs," said Hillary Young, former Smithsonian post-doctoral fellow and current assistant professor at the University of California, Santa Barbara. "While this correlation has been the topic of much scientific debate, ours is one of the only studies to offer clear experimental evidence." Young is the lead author of the research paper.
Using 24 acres of savanna that had been fenced off for 15 years to keep large animals out in central Kenya, the scientists examined rodent populations inside and outside the area for three years.
They also tracked the presence of Bartonella infections in the rodents and their fleas. Bartonella, a group of bacteria found around the world, can cause bartonellosis in humans—an infectious disease that can lead to joint swelling, liver damage, memory loss and other symptoms.
The team regularly trapped rodents in the area, represented by several species of mice, rats and gerbils. Each rodent was identified to species, sexed, weighed and marked. A blood sample and fleas, if they were present, were collected from each rodent for testing before it was released where it was captured.
The team found that rodent and, consequently, flea abundance doubled inside the area that excluded large wildlife. Without having to compete with large animals for food, the rodent population grew twofold. When the rodents and fleas in the area doubled, the team found that those infected with Bartonella doubled as well.
The removal of large wildlife from the ecosystem could be directly linked to the increase in rodents and the rodent-borne disease, thus increasing risk to humans. These results suggest that a partial solution to problems of rodent-borne disease could come in the form of wildlife conservation.
"Africa's large wildlife faces many threats—elephants, rhinos and other large mammals continue to decline in the face of growing human populations, expanding agriculture and the impacts of poaching and wildlife trade," said Helgen. "While we know that conservation is good for wildlife and for economies reliant on tourism, our study shows a less-intuitive dimension of conservation that could greatly benefit the people living alongside wildlife."
This study is the first of several more to come. The team plans to expand its research to a wider suite of infectious diseases to see which might respond similarly and which do not. They will also undertake further studies not only in carefully controlled experimental sites but in the "real world" where humans have already altered the landscape and eradicated much of the large wildlife.
The team's research has implications well beyond Africa. "While rodent-borne diseases are a major issue in Africa, they are everywhere—Europe, Asia, North and South America," Young said. "What we find here may very well be applicable in other parts of the world."
John Gibbons | Eurek Alert!
Malaysia's unique freshwater mussels in danger
27.09.2016 | The University of Nottingham Malaysia Campus
How to detect water contamination in situ?
22.09.2016 | Tomsk Polytechnic University (TPU)
Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.
Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...
The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.
“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...
With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.
Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...
For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.
Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...
At AKL’16, the International Laser Technology Congress held in May this year, interest in the topic of process control was greater than expected. Appropriately, the event was also used to launch the Industry Working Group for Process Control in Laser Material Processing. The group provides a forum for representatives from industry and research to initiate pre-competitive projects and discuss issues such as standards, potential cost savings and feasibility.
In the age of industry 4.0, laser technology is firmly established within manufacturing. A wide variety of laser techniques – from USP ablation and additive...
27.09.2016 | Event News
23.09.2016 | Event News
20.09.2016 | Event News
27.09.2016 | Life Sciences
27.09.2016 | Physics and Astronomy
27.09.2016 | Life Sciences