A new strain of rabies has been discovered in southern New Mexico, federal and state health officials confirmed Tuesday.

While it doesn't present any more of a public health threat than the known strains of the potentially fatal disease, the discovery is generating curiosity in scientific circles because it's the first new strain to be found in the United States in several years.

"It's exciting. It's related to another bat strain. It's similar but unique, so the question is what's the reservoir for this strain," state public health veterinarian Paul Ettestad said.

When scientists talk about the reservoir, they are referring to animals known to host the virus. In many cases, that can be bats, skunks or raccoons. Those animals usually aren't tested because it's assumed they have regular strains of rabies.

Tests are done when it shows up in other animals, including dogs, cats, horses and foxes, Ettestad said.

That was the case when a 78-year-old Lincoln County woman was bitten by a rabid fox in April. Genetic testing at a U.S. Centers for Disease Control and Prevention lab in Atlanta confirmed the strain was one that never before had been identified.

State officials suspect the rabid fox came in contact with an infected bat that was carrying the strain. "It has probably been out there for some time. We just haven't looked that hard for it and by chance we found it," Ettestad said of the new strain.

New Mexico health and wildlife officials have been tracking rabies in the fox population since 2007, when a separate strain found in Arizona gray foxes crossed into New Mexico.

The Health Department will continue working with state wildlife officers to collect foxes that are found dead along roadways in Lincoln County as well as freshly dead bats in hopes of determining where the newly identified strain is coming from, Ettestad said.

About 100,000 animals are tested for rabies each year in the U.S. Of the roughly 6,000 that are positive, only a fraction are tested to determine the type of strain.

So far this year, New Mexico has had only two confirmed rabies cases - a bat from Dona Ana County and the fox from Lincoln County. The state isn't considered a hot zone for rabies and in fact ranks near the bottom when it comes to the number of cases reported each year.

The virus infects the central nervous system. Early symptoms in people can include fever, headache and general weakness or discomfort.

State health officials warned people to stay away from wild or unfamiliar animals and advised parents to teach their children to never touch a bat or other wild animal.