Most infectious diseases infect multiple host species, but to date, efforts to quantify the frequency and outcome of cross-species transmission (CST) of these diseases have been severely limited.
This lack of information represents a major gap in knowledge of how diseases emerge, and from which species they will emerge.
A paper published this week in the journal Science by a team of researchers led by Daniel Streicker of the University of Georgia has begun to close that gap.
Results of a study, conducted by Streicker and co-authors from the U.S. Centers for Disease Control, the University of Tennessee-Knoxville, and Western Michigan University, provide some of the first estimates for any infectious disease of how often CST happens in complex, multi-host communities--and the likelihood of disease in a new host species.
"Some of the deadliest human diseases, including AIDS and malaria, arose in other species and then jumped to humans," said Sam Scheiner of the National Science Foundation (NSF)'s Division of Environmental Biology, which co-funded the research with NSF's Directorate for Geosciences through the joint NIH-NSF Ecology of Infectious Diseases Program.
"Understanding that process," said Scheiner, "is key to predicting and preventing the next big outbreak."
Rabies is an ideal system to answer these questions, believes Streicker.
The disease occurs across the country, affects many different host species, and is known to mutate frequently. Although cases of rabies in humans are rare in the U.S., bats are the most common source of these infections.
To determine the rate of CST, and what outcomes those transmissions had, Streicker and his colleagues used a large dataset, unprecedented in its scope, containing hundreds of rabies viruses from 23 North American bat species.
They sequenced the nucleoprotein gene of each virus sample and used tools from population genetics to quantify how many CST events were expected to occur from any infected individual.
Their analysis showed that, depending on the species involved, a single infected bat may infect between 0 and 1.9 members of a different species; and that, on average, CST occurs only once for every 72.8 transmissions within the same species.
"What's really important is that molecular sequence data, an increasingly cheap and available resource, can be used to quantify CST," said Streicker.
Scientist Sonia Altizer of UGA agrees.
"This is a breakthrough," said Altizer. "The team defined, for the first time, a framework for quantifying the rates of CST across a network of host species that could be applied to other wildlife pathogens, and they developed novel methods to do it."
The researchers also looked at the factors that could determine the frequency of CST, using extensive data about each bat species, such as foraging behavior, geographic range and genetics.
"There's a popular idea that because of their potential for rapid evolution, the emergence of these types of viruses is limited more by ecological constraints than by genetic similarity between donor and recipient hosts," said Streicker. "We wanted to see if that was the case."
He found, instead, that rabies viruses are much more likely to jump between closely related bat species than between ones that diverged in the distant past.
Overlapping geographic range was also associated with CST, but to a lesser extent.
"CST and viral establishment do not occur at random, but instead are highly constrained by host-associated barriers," Streicker said. "Contrary to popular belief, rapid evolution of the virus isn't enough to overcome the genetic differences between hosts."
Streicker believes that what he and colleagues have learned about bat rabies will be influential in understanding the ecology, evolution and emergence of many wildlife viruses of public health and conservation importance.
"The basic knowledge we've gained will be key to developing new intervention strategies for diseases that can jump from wildlife to humans."
Streicker is continuing his work with rabies and bats with funding for a three-year study from NSF.
He and Altizer, in collaboration with investigators at the CDC, University of Michigan and the Peruvian Ministries of Health and Agriculture, will explore how human activities affect the transmission of the rabies virus in vampire bats in Peru--and how those changes might alter the risk of rabies infection for humans, domesticated animals, and wildlife.Media Contacts
Cheryl Dybas | EurekAlert!
Embryonic development: How do limbs develop from cells?
18.05.2018 | Humboldt-Universität zu Berlin
Reading histone modifications, an oncoprotein is modified in return
18.05.2018 | American Society for Biochemistry and Molecular Biology
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.
Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...
A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.
Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
18.05.2018 | Power and Electrical Engineering
18.05.2018 | Information Technology
18.05.2018 | Information Technology