Arizona rabies spike blamed on skunks

NATIONAL REPORT — In Arizona, skunk rabies is on the incline, despite noted decreases in reported cases for the rest of the country.

In fact, the total number of reported cases of rabies in the United States dropped 3.1 percent in 2008 when compared with 2007. Rabies cases in dogs dropped a whopping 19.4 percent, cases in foxes dropped 1.7 percent and even in bats — a notorious reservoir for the virus — the number of cases fell 6.7 percent. Across the board the numbers look positive, though there is one exception: a 7.7 percent uptick of rabies cases in skunks.

Nowhere in the United States is the rabid skunk conundrum more prevalent than in Arizona. In 2007, the state reported just 13 cases of rabid skunks. In 2008, that number jumped to 51, and by 2009 the number of reported rabies cases in skunks ballooned to 144. While national data on rabies cases are not yet available for 2009, statistics gathered from Arizona show that the state experienced a nearly 60 percent spike in reported rabies cases in 2009 when compared with 2008.

"Last year we ended up having a record number of rabid animals reported during the year," says Craig Levy, program manager of the Arizona Department of Health Service's Vector Borne Disease Program. "In fact, we shattered the previous record, which was in 2008 with 176 animals reported. Last year, we had 280."

The presence of rabid skunks in Arizona is a relatively new trend, according to Charles Rupprecht, DVM, head of the rabies program at the Centers for Disease Control (CDC) and Prevention. After testing skunks from Arizona, the CDC was able to determine that a strain of rabies confined to bats jumped over to the state's skunk population. And that is posing greater concern about the potential threat to domestic animals and people.

"If you go ahead and look at the approximately 300 to 400 rabid dogs and cats reported last year in the United States, all of those were due to infection by wildlife, either wild carnivores like skunks and raccoons or from infected bats," Rupprecht notes.

Meanwhile, Levy points out that rabies activity tends to fluctuate based on wildlife populations, and increased competition for resources may drive rabid animals toward more densely populated areas.

"Anytime we see more rabies in wildlife we're going to see more exposures occurring to pet animals, livestock and people," Levy says.

Both Levy and Rupprecht urge veterinarians to encourage their customers to make sure their pets are vaccinated for rabies, and to make sure those vaccines are up to date. Rupprecht also suggests that veterinarians should consider vaccinating animals such as horses if a rabies outbreak is occurring in the region.

Data on national rabies trends during 2009 are slated for release later this year, which should help shed light on whether the surge of cases in Arizona is an isolated incident or a bigger problem.

"We are a little bit ahead in 2010 of where we were at this point in 2009, but that doesn't mean anything for the long-term forecast," Levy says. "I'm hoping we don't set any new records."

Mr. Sweeney is a freelance journalist in Chicago.