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, it's the first new strain to be found in the United States in several years.
The new rabies strain was found in a 78-year-old woman 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," said state public health veterinarian Paul Ettestad.
"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," he added.
A reservoir refers to animals that carry and spread the virus. In many cases, that can be bats, skunks or raccoons. Those animals usually aren't tested because it's assumed they have known strains of rabies.
Rabies evolves to match the animals it infects. Dog rabies -- the strain most specific to dogs -- has not been seen anywhere in the United States since 2004.
Rabies kills more than 50,000 people a year globally, according to the World Health Organization. It is easily prevented with a vaccine, but many people do not realize they have been infected and once symptoms begin to show, it is almost impossible to treat. There are only a couple of cases a year in the U.S.