An international team of scientists is using satellite imagery to help determine whether there is a relationship between changes in the landscape in Paraguay and outbreaks in that country of Hantavirus Pulmonary Syndrome, a disease transmitted from rats to humans that affects the respiratory system.
A team of scientists from Kansas State University and their partners are examining areas in Paraguay affected with the virus and looking closer at the landscape there to gain a better understanding of what areas containing rodents infected with the disease look like. The team is relying on a combination of satellite data and site visits to do their work.
“What we’re doing is trying to analyze the spatial environment and figure out what it is about the physical structure of the landscape that is associated with the persistence of the virus’s presence,” Doug Goodin, a geography professor at Kansas State University who is involved with the project, said in a telephone interview.
Hantavirus Pulmonary Syndrome is one of many conditions that erupt from the Hantavirus, strains of which can be found throughout South America and Asia, according to the American Lung Association. Humans get the disease from rodents in a variety of ways: from inhaling airborne excrement or being bitten by the animals, and possibly through contaminated food or water.
Initial symptoms are similar to that of a cold, and also include fever and muscle aches. As the disease progresses, the symptoms include severe respiratory difficulties, including the often-deadly adult respiratory distress syndrome, according to the American Lung Association. The disease has only been on the radar screens of scientists in the Americas since 1993, when an outbreak occurred in the southwest United States, Goodin said.
The project has funding of $1.8 million over four years through a joint program involving the National Institute of Health and the National Science Foundation. The project is currently in its second year.
When the project began, the team took a trip to Paraguay and zeroed in on six study sites in the Department of Canendiyu, which surround the Mbaracayu biosphere reserve, Goodin said.
The team’s hypothesis so far is that outbreaks of the virus can be associated with fragmentation and human disturbance of the landscape, Goodin said.
When land changes happen, the rodent population in the area is put under stress and has to compete with each other for resources. Another hypothesis is that aggressive behavior between the rodents can lead to more transmission of the virus. And since land changes are a result of human behavior, the affected areas often have a higher concentration of population, spreading the disease to more human hosts.
Scientists are hoping that identifying the typical environments of infected rats will better enable them to predict where an outbreak can occur.
Goodin said that the virus has not reached alarming proportions in Paraguay , but that the health monitoring in the area is rather underdeveloped so it could be affecting more people than is realized.
To get a better understanding of the landscape, the team is examining data from the Quickbird satellite, U.S. government Landsat data and vegetation from the Spot 4 and Spot 5 satellites, said Dave Koch, another Kansas State University scientist who works with Goodin on the project, in a telephone interview. The Landsat data helps the team get a “big picture” look at the area, while with the Quickbird data the scientists can focus on the location of individual trees and shrubs in the landscape.
If the project continues, the team might explore the use of other remote sensing technologies such as radar. The preferred habitat for the rodent species Akodon Montensis, or “cursor mouse,” that often hosts the virus, can be dense and woody, making it hard to gauge its features from satellite data.
“The area is sort of a combination of forest, open areas and deforested areas, and radar might help us kind of tease that apart,” Koch said.
The research team includes scientists with the Southern Research Institute of Birmingham, Ala., Texas Tech University of Lubbock, Texas , New Mexico State University of Las Cruces, and the Fundacin Moises Bertoni in Paraguay, a non-government organization focused on conservation efforts.
The use of remote sensing technologies to study the relationship between landscape and disease is nothing new, Goodin said. Previous s tudies have been done looking at diseases transmitted through mosquitoes, such as malaria and yellow fever, as well as the relationship between ocean temperatures and outbreaks of cholera, he said.