Going to the dogs
A FATAL tropical disease has infected large numbers of foxhounds in the US. Public health officials fear that humans may contract the disease if the dogs come into contact with sandflies, which transmit the parasite that causes leishmaniasis.
Late last year, the Millbrook Hunt Club in New York State realised that many of its foxhounds were sick and dying. The dogs were losing their hair, they had skin lesions, swollen limbs and joints, and were wasting away. When vets analysed fluid from the joints of one dog they found the leishmaniasis parasite.
This disease, which in humans can cause fever, anorexia, diarrhoea and darkening of the hands and feet, is commonly found in the Mediterranean and the tropics. It can kill humans. Usually, North Americans -- and their dogs -- only get the disease if they travel to the tropics. So Peter Schantz and his colleagues at the CDC were mystified when they learned that half the foxhounds at Millbrook tested positive.
They tested other dogs living in the area, as well as horses and wild rodents. All the tests were negative, as were those on the kennel's personnel. But hunting clubs often travel, so they advised the Masters of Foxhounds Association of America, based in Leesburg, Virginia, to suspend all travelling for this year's season while they tried to work out what was going on.
By the second week of July, they'd tested 6845 of around 12 000 foxhounds registered with the MFHA. At least 12 per cent of the dogs have some antibodies, suggesting that they have been exposed to the parasite. Around 2 per cent of the dogs have a strong response on the antibody test, indicating the need for more testing to see if they are actively infected, says Dennis Foster, executive director of the MFHA.
"We have found infection now in 29 states and the Ontario province of Canada," says Schantz. Public health officials recommend putting down infected dogs or placing them in quarantine. They hope that these measures will be enough to contain the outbreak.
So far, tests on more than 450 domestic dogs from 40 states have all proved negative. And there have been no human cases. "We believe we have it in control," says Foster. "Those hunts that are completely negative will be able to resume as normal this season."
Corrie Brown of the University of Georgia in Athens, an expert on diseases that can be transmitted from animals to humans, says that leishmaniasis is having a "very scary introduction into the US. We're probably going to see more leishmaniasis in humans as a result." Epidemiologists are unsure how the parasite entered the country. "How did it get in? Nobody really knows," says Brown.
New Scientist issue: 29th July 2000
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