Sep. 6, 2000 Aug. 25, 2000 -- Results of DNA and blood tests obtained by scientists at North Carolina State University's College of Veterinary Medicine and the National Centers for Disease Control and Prevention (CDC) have confirmed cases of visceral canine leishmaniasis -- a rare, often fatal tropical disease that can be transmitted to humans and other animals -- in 21 U.S. states and southern Canada.
The test results suggest leishmaniasis is substantially more widespread in North American canine populations than originally thought.
"We have a very serious disease that leads to chronic debilitation and kidney failure in dogs, and can lead to their death. Unfortunately the disease is extremely hard to diagnose," says Dr. Edward Breitschwerdt, professor of small animal internal medicine at NC State, who helped lead the research effort to facilitate more widespread testing for leishmaniasis after diagnosing the disease at a New York hunt club last spring.
Until researchers determine how leishmaniasis is transmitted in the United States, the threat to human health is not completely known, Breitschwerdt says. Direct contact transmission would pose a far smaller risk than transmission by insects like sand flies or ticks. That mode of transmission, Breitschwerdt says, could create a public health concern.
Leishmaniasis is a parasitic infection and most often occurs in rural areas of the tropics and subtropics, where the most common species of the parasite is transmitted by the bite of an infected female sand fly. Symptoms of leishmaniasis include skin lesions, nose bleeds, swollen lymph glands, weight loss, seizures, hair loss, kidney failure and swollen limbs and joints.
The disease is potentially fatal in humans, but can be treated. While there is no cure for leishmaniasis in dogs, it can be put into remission.
Breitschwerdt says leishmaniasis is prevalent in southern Europe, India and South America, but, until very recently, was not thought to be present in the United States. "I think there is the possibility that there could have been human cases in the United States that weren't diagnosed," he says. Ongoing research efforts should allow scientists to determine the source of the U.S. canine Leishmaniasis, how it's being transmitted, and if the cases in different states come from the same strain of the organism.
Breitschwerdt and his colleagues implemented the new diagnostic tests at the College of Veterinary Medicine last spring in response to a disease outbreak among foxhounds at a New York hunt club. When foxhounds at the club began losing weight and suffering from skin lesions, seizures, swollen limbs and joints, and in most cases fatal kidney failure, the club's attending veterinarian turned to veterinary medicine researchers at NC State for help. Using the DNA and blood tests, Breitschwerdt and his team were able to confirm that the disease was canine leishmaniasis.
The NC State team has been collaborating with the CDC, the Walter Reed Army Institute of Research and the Dutchess County (New York) Department of Health to investigate the New York Leishmaniasis outbreak.
In conjunction with the CDC, they've tested foxhounds from other regions and identified canine leishmaniasis in 21 other states, including North Carolina, and southern Canada. "So we've gone from an outbreak in New York to literally a national epidemic that's probably been smoldering for 15 to 20 years," Breitschwerdt says. It's still not clear how the dogs in New York became infected.
Breitschwerdt's research and testing team is made up of more than a dozen NC State students, clinicians, pathologists and other researchers, including Dr. Michael Levy, professor of parasitology; Dr. Amanda Gaskin, internal medicine resident; Dr. Adam Birkenheur, graduate student; and Lindsay Tomlinson, pathology instructor.
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