Detecting Disease from Space: Hot Spots of Disease Transmission in the Serengeti Ecosystem of Northern Tanzania
Original report written by UCSB graduate student Lacey Hughey. Interview and editing by Bailee Abell.
In the heart of Eastern Africa is almost 7,000 square miles of a grassland ecosystem. It is home to millions of large mammals that partake in what is regarded to be one Earth’s most remarkable mass game migrations that takes place year after year, despite disease outbreaks and environmental and human threats. This phenomenon—known as the Greater Serengeti Ecosystem—caught the interest of Lacey Hughey, a graduate student at UCSB who aims to improve the livelihood of the ecosystem’s inhabitants. With support from an Earth Research Institute fellowship, Hughey is examining how new satellite-based surveying systems can help reduce disease transmission between wildlife and livestock.
“I became interested in the role that protected areas play in conserving large, mobile species while working as a Wildlife Technician for the US National Park Service in northern California,” Hughey said. “Considering the difficulties we have addressing this issue in a country as developed as the US lead to my specific interest in addressing these challenges in less developed countries...I was instantly hooked on the extreme beauty of this vast, ancient ecosystem that's still fueled by the movements of large, mobile species like wildebeest and elephants.”
Tracking livestock movements is critical to understanding and predicting patterns of disease transmission between wildlife and livestock, which is a global issue that directly impacts local economies as well as entire ecosystems, including the Greater Serengeti Ecosystem. The Greater Serengeti Ecosystem is a region of Eastern Africa that represents the remains of a large, mammal-dominated ecosystem that has existed for over 12,000 years, according to the World Wildlife Fund.
Successful management of the greater Serengeti Ecosystem is critical for Tanzanian economy, as it annually generates thousands of jobs and millions of dollars of tourism each year. Usually, fences protect cattle from interaction with wildlife and reduce disease transmission. However, fencing in the Serengeti would disrupt the movement of over one million white-bearded wildebeest, whose mass migration is a key component of the ecosystem’s function. Increased spread of disease between livestock and wildlife leads to the decline of animal health, loss of individuals, and greatly impacts the function of both the Serengeti and the Tanzanian economy.
“Livestock are crucial to the socioeconomic stability of communities in this area,” Hughey said, “but recent and rapid expansion in livestock production has raised concerns about the long-term sustainability of such unchecked growth. However, conservation managers have been unable to accurately track and assess these changes with traditional methods, so we have been working collaboratively to develop an affordable and accurate satellite based method that can be used in the near future.”
Hughey—alongside assistant professor Douglas McCauley of the Department of Ecology, Evolution, and Marine Biology, and researchers at the University of California, Santa Barbara— remotely censused the livestock in the Greater Serengeti Ecosystem through the use of high-resolution satellite imagery. Following this, the satellite images were uploaded to UCSB’s cloud-based image analysis platform BisQue—a database designed by researchers at the UCSB Vision Research Lab—for undergraduate volunteers to annotate the location of individual animals and report the abundance of livestock in the censused area.
Hughey plans to use these results to estimate the relationship between the density of livestock present and the density of the semi-permanent corrals, or bomas, installed by livestock owners in the area to protect the cattle from nighttime predators. Over time, the results of this research will be used to estimate livestock densities across the Greater Serengeti Ecosystem in order to further examine disease transmission rates between livestock and wildlife.
This research has lead Hughey and her team to aim to develop a low-cost system for surveying livestock density across large and remote areas not only in the Greater Serengeti Ecosystem, but in other regions of the world as well. Their goal is to validate methods that can be adapted to census livestock and wildlife in any landscape open to facilitate remote sensing and where legal or technical limitations prevent the use of manned or unmanned aerial survey methods.
“If we are successful in finding a way to efficiently and accurately survey livestock densities with satellite imagery, there will be numerous directions for future study,” Hughey said. “For example, there is immediate interest in using these results to identify ‘hot spots’ of disease transmission between livestock and wildlife so that vaccination efforts can be targeted more effectively in the future.”
Hughey’s project was made possible with the help of the Earth Research Institute, which granted her the fellowship that supported the time she spent acquiring and processing the imagery used for livestock censusing. This project allowed her to develop skills in satellite image acquisition and processing, and she has built new relationships in collaborating with researchers and conservation organizations in the UK and Tanzania. “[This project] is helping to answer a question of immediate concern to land managers in Tanzania and will hopefully improve the efficiency of livestock and wildlife monitoring efforts in the near future.”