Why did the cat cross Windsor Road?

Illinois Natural History Survey and University of Illinois researchers don't think the answer is as simple as "to get to the other side," in the words of that old joke about the chicken.

So they're embarking this month on a study of free-ranging cats near the UI's South Farms. The study might tell them not only where the felines go, but when and how often. It also might reveal the frequency with which the roving cats cross paths with livestock and wildlife such as migratory birds – not to mention with people.

That's of particular interest, in part, because cats are the "definitive host" of a parasite called Toxoplasma gondii, natural history survey scientist Nohra Mateus-Pinilla said. Which is to say that cats are the only animal known to provide a home for the parasite during its reproduction cycle, said Mateus-Pinilla, a veterinary wildlife epidemiologist and a principal investigator on two cat studies planned this year.

In addition to the South Farms research, a related project will examine free-ranging cats in the UI's Allerton Park near Monticello, providing the first look at their impact on the spread of Toxoplasma gondii to wildlife in a natural area.

Almost any warm-blooded animal can be infected with Toxoplasma gondii, which cats probably get from prey – mice and the like – already infected in a kind of self-propagating cycle, said Milton McAllister, a pathobiology professor in the UI College of Veterinary Medicine and leading expert on the parasite.

Cats spread it in their feces by the millions. In microscopic, dormant, hard-shelled form, it can then survive for long periods in the soil, water and elsewhere in the environment waiting for another animal to infect, whether another cat, a mouse, a pig, a cow, an adult working in the garden or a child playing in a sandbox.

People probably get the parasite, which is contracted by ingestion, from unintentionally transmitting it hand to mouth, or by eating undercooked infected meat. McAllister said a quarter of the people in the U.S. have it, 70 to 80 percent worldwide.

"Most people who are infected do not have any symptoms at all," he said.

At worst, healthy people may suffer briefly from mild fever, sore throat or muscle aches as a result of toxoplasmosis, the condition caused by the parasite, and pass it off as a touch of the flu. But the pathogen can be dangerous, even deadly, for those with compromised immune systems, such as AIDS patients or folks undergoing cancer treatments and organ transplants.

In addition, Toxoplasma gondii is dangerous for unborn children, the reason pregnant women are warned about contact with cats and cat litter.

"It affects the brain, it affects the heart and it can cause birth defects," McAllister said.

He said there's also evidence that the pathogen can have effects not noticeable initially, but later reflected in conditions such as vision loss, learning deficits and even the development of schizophrenia.

Like most people, infected cats, while thought to be the leading transmitters, generally aren't affected, McAllister said.

The UI researchers conducting the studies took pains to emphasize that they're in no way discouraging the keeping of cats as pets. Cats kept mostly indoors are a low risk for contracting, carrying or transmitting the parasite, although cats allowed to roam have a greater chance of being infected.

And there are a lot of cats, both abandoned and born wild, running around in the environment with little of a substantial nature known about just where they go and what they do.

Feral "barn cats," in fact, are something of a farm tradition, one with potential ramifications for modern, animal-dense, mega-livestock operations and for residential development in rural locales, which is increasingly putting the suburbs, farms and natural areas in proximity.

It makes sense to look at what roaming cats are up to and recent technology, much of it developed at the UI, along with available living laboratories such as the South Farms and Allerton, offers the opportunity to do so in greater detail than ever before, said Mateus-Pinilla and Richard Warner, a UI natural resources and environmental sciences professor who's also a principal investigator on both studies.

The researchers will use live traps to catch cats at multiple sites on university property several times for about a year. Feral cats will be sedated briefly using the same sedative veterinarians employ when examining an animal.

Cats at the South Farms will be fitted with radio collars to track their activities by means of an "automated telemetry system" that compares their location with the locations of a series of receiver towers erected in the area, as well as mobile receiving units, about every 10 seconds.

Jeff Horn, the UI graduate student who will collect the data, said the collars are designed to break away if a cat gets stuck on something by the collar.

The technology can locate a collared cat within a few meters, tell if it is moving or at rest, and more, said Horn and Mike Ward, a natural history survey scientist and UI natural resources and environmental sciences professor who helped develop the system.

At Allerton Park, researchers will take small blood samples from feral cats and other wildlife, including raccoons, opossums, squirrels, rabbits, skunks and mice. The blood samples will be tested for Toxoplasma gondii.

Emily Jewell, a graduate student in the UI veterinary college, will collect the parasite data at Allerton. Cats trapped around the South Farms won't be blood tested.

The researchers will put microchip sensors, like those many pet owners use to identify their animals today, in all wildlife (not cats) trapped at Allerton. The chips will identify animals if they're caught again and allow their conditions to be tracked.

Data mining technology, also developed at the UI, eventually will be applied to the information collected in the studies, which should provide a basis for computer modeling the movement and impact of cats in the environment, Ward said.

He and Warner said the techniques developed should be useful for studying other animals, too. Mateus-Pinilla is particularly interested in the use of wildlife as "biosensors" for monitoring the spread of pathogens that can affect both animals and people.