Domestic Cats, and Wild Bobcats and Pumas, Living in Same Area Have Same Diseases

February 3, 2012
Domestic cats, wild bobcats and pumas that live in the same area share the same diseases.

And domestic cats may bring them into human homes, according to results of a study of what happens when big and small cats cross paths.

Initial results of the multi-year study are published today in the scientific journal PLoS One by a group of 14 authors.

The joint National Science Foundation (NSF) and National Institutes of Health (NIH) Ecology and Evolution of Infectious Diseases (EEID) Program funded the study. Scientists at Colorado State University and other institutions conducted the research.

It provides evidence that domestic cats and wild cats that share the same outdoor areas in urban environments also can share diseases such as Bartonellosis and Toxoplasmosis. Both can be spread from cats to people.

"Human-wildlife interactions will continue to increase as human populations expand," said Sam Scheiner, program director for EEID at NSF.

"This study demonstrates that such interactions can be indirect and extensive," said Scheiner. "Through our pets we are sharing their diseases, which can affect our health, our pets' health and wildlife health."

The study looked at urban areas in California and Colorado. Its results show that diseases can spread via contact with shared habitat.

All three diseases the scientists tracked--Toxoplasmosis, Bartonellosis and FIV, or feline immunodefiency virus--were present in each area.

The research also demonstrates that diseases can be clustered due to urban development and major freeways that restrict animal movement.

"The results are relevant to the big picture of domestic cats and their owners in urban areas frequented by wild cats such as bobcats and pumas," said Sue VandeWoude, a veterinarian at Colorado State and co-leader of the project.

"The moral of this story is that diseases can be transmitted between housecats and wildlife in areas they share, so it's important for pet owners to keep that in mind."

The researchers followed wild and domestic cats in several regions of Colorado and California to determine whether the cats had been exposed to certain diseases.

The effort includes data from 800 blood samples from felines of all sizes, including 260 bobcats and 200 pumas, which were captured and released, and 275 domestic cats.

"As human development encroaches on natural habitat, wildlife species that live there may be susceptible to diseases we or our domestic animals carry and spread," said Kevin Crooks, a biologist at Colorado State and co-leader of the project.

"At the same time, wildlife can harbor diseases that humans and our pets can in turn get. Diseases may be increasingly transmitted as former natural areas are developed."

The project also looked at whether bobcats in southern California were segregated into different populations by major highways.

By analyzing genetic and pathogen data, the scientists found that bobcats west or east of Highway 5 near Los Angeles rarely interbred, but that the bobcats did cross into each other's territory often enough to share diseases such as FIV.

"The evidence suggests that bobcats are moving across major highways, but are not able to easily set up new home territories," said VandeWoude.

"They can, however, spread diseases to one another when they cross into each other's territories. This could result in inbreeding of the bobcats trapped by urban development and end up in the spread of diseases."

VandeWoude and Crooks say that the results don't necessarily mean that all domestic cats that are allowed to roam outdoors are at a high level of risk. They plan further studies to better assess that risk.

It does mean that domestic cats and wild cats who share the same environment--even if they do not come into contact with each other--also can share diseases.

The findings show that pumas are more likely to be infected with FIV than bobcats or domestic cats. While FIV cannot be transmitted to people, it is highly contagious among felines.

The rate of Toxoplasmosis was high in pumas and bobcats across Colorado and California.

Toxoplasmosis is caused by a parasite that, when carried by healthy people, has no effect but that can cause complications for infants and adults with compromised immune systems.

Cats only spread Toxoplasmosis in their feces for a few weeks following infection with the parasite. Like humans, cats rarely have symptoms when first infected.

Bartonellosis is a bacterial infection also called cat scratch disease. If someone is scratched by a cat with Bartonellosis, the scratch may become infected, but the infection is usually a mild one.

Other studies underway include a fine-scale analysis of urban landscape features that affect disease incidence; evaluation of pathogen exposure and transmission in bobcats; and a survey of domestic cat owners about their attitudes toward risks for pets from wildlife.

Large-scale projects looking at movement patterns of bobcats and pumas in Colorado, and a motion-activated camera analysis of human and wildlife interactions along urban areas, are also in progress.

The take-home message, the researchers say, is that life in the wild may not be so wild after all.

In addition to VandeWoude and Crooks, co-authors of the paper are: Sarah Bevins, Scott Carver, Mo Salman and Michael Lappin of Colorado State University; Erin Boydston, Lisa Lyren and Robert Fisher of the Western Ecological Research Center, U.S. Geological Survey; Mat Alldredge and Kenneth Logan of the Colorado Division of Parks and Wildlife; Seth Riley of the National Park Service in Thousands Oaks, Calif.; and T. Winston Vickers and Walter Boyce of the University of California at Davis.

NSF's Directorates for Biological Sciences and Geosciences, along with NSF's Directorate for Social, Behavioral & Economic Sciences, support the EEID Program.

For more information on the NSF-NIH EEID Program, please see NSF's special report: Ecology of Infectious Diseases.

-NSF-

Breakthrough Study Confirms Cause of Short Gamma-Ray Bursts

WASHINGTON -- A new supercomputer simulation shows the collision of two neutron stars can naturally produce the magnetic structures thought to power the high-speed particle jets associated with short gamma-ray bursts (GRBs). The study provides the most detailed glimpse of the forces driving some of the universe's most energetic explosions.

The state-of-the-art simulation ran for nearly seven weeks on the Damiana computer cluster at the Albert Einstein Institute (AEI) in Potsdam, Germany. It traces events that unfold over 35 milliseconds -- about three times faster than the blink of an eye.

GRBs are among the brightest events known, emitting as much energy in a few seconds as our entire galaxy does in a year. Most of this emission comes in the form of gamma rays, the highest-energy form of light.

"For the first time, we've managed to run the simulation well past the merger and the formation of the black hole," said Chryssa Kouveliotou, a co-author of the study at NASA's Marshall Space Flight Center in Huntsville, Ala. "This is by far the longest simulation of this process, and only on sufficiently long timescales does the magnetic field grow and reorganize itself from a chaotic structure into something resembling a jet."

GRBs longer than two seconds are the most common type and are widely thought to be triggered by the collapse of a massive star into a black hole. As matter falls toward the black hole, some of it forms jets in the opposite direction that move near the speed of light. These jets bore through the collapsing star along its rotational axis and produce a blast of gamma rays after they emerge. Understanding short GRBs, which fade quickly, proved more elusive. Astronomers had difficulty obtaining precise positions for follow-up studies.

That began to change in 2004, when NASA’s Swift satellite began rapidly locating bursts and alerting astronomers where to look.

"For more than two decades, the leading model of short GRBs was the merger of two neutron stars," said co-author Bruno Giacomazzo at the University of Maryland and NASA's Goddard Space Flight Center in Greenbelt, Md. "Only now can we show that the merger of neutron stars actually produces an ultrastrong magnetic field structured like the jets needed for a GRB."

A neutron star is the compressed core left behind when a star weighing less than about 30 times the sun's mass explodes as a supernova. Its matter reaches densities that cannot be reproduced on Earth -- a single spoonful outweighs the Himalayan Mountains.

The simulation began with a pair of magnetized neutron stars orbiting just 11 miles apart. Each star packed 1.5 times the mass of the sun into a sphere just 17 miles across and generated a magnetic field about a trillion times stronger than the sun's.

In 15 milliseconds, the two neutron stars crashed, merged and transformed into a rapidly spinning black hole weighing 2.9 suns. The edge of the black hole, known as its event horizon, spanned less than six miles. A swirling chaos of superdense matter with temperatures exceeding 18 billion degrees Fahrenheit surrounded the newborn black hole. The merger amplified the strength of the combined magnetic field, but it also scrambled it into disarray.

Over the next 11 milliseconds, gas swirling close to the speed of light continued to amplify the magnetic field, which ultimately became a thousand times stronger than the neutron stars' original fields. At the same time, the field became more organized and gradually formed a pair of outwardly directed funnels along the black hole's rotational axis.

This is exactly the configuration needed to power the jets of ultrafast particles that produce a short gamma-ray burst. Neither of the magnetic funnels was filled with high-speed matter when the simulation ended, but earlier studies have shown that jet formation can occur under these conditions.

"By solving Einstein's relativity equations as never before and letting nature take its course, we've lifted the veil on short GRBs and revealed what could be their central engine," said Luciano Rezzolla, the study's lead author at AEI. "This is a long-awaited result. Now it appears that neutron star mergers inevitably produce aligned jet-like structures in an ultrastrong magnetic field."

The study is available online and will appear in the May 1 edition of The Astrophysical Journal Letters.

The authors note the ultimate proof of the merger model will have to await the detection of gravitational waves -- ripples in the fabric of space-time predicted by relativity. Merging neutron stars are expected to be prominent sources, so the researchers also computed what the model's gravitational-wave signal would look like. Observatories around the world are searching for gravitational waves, so far without success because the signals are so faint.



Lynn Chandler
NASA's Goddard Space Flight Center, Greenbelt, Md.

http://www.nasa.gov/topics/universe/features/gamma-ray-engines.html