Concern Over Transmission of Spongiform Encephalopathy
Language:  English  Article Type:CSO   [Article by Nigel Hawkes, Science Editor: "Zoo Antelope  Catch Mad Cow Disease"] [Text] Scientists at London zoo have discovered that a strain of "mad cow disease" affecting a type of antelope can be transmitted much more easily than was thought. The finding uncovers a threat to breeding other species in captivity unless it can be shown that they are not equally vulnerable. The scientists say there is no evidence that similar transmission is occurring among cows. The zoo's small herd of kudu, spiral-horned antelopes closely related to cows, has been severely hit by a disease similar to bovine spongiform encephalopathy (BSE). Of eight animals born in the herd since 1987, five have contracted the disease. Only one of the five could have eaten feed containing protein from sheep, believed to be the origin of the outbreak. The kudu is not the only zoo species to suffer the disease since it appeared in cows. It has also been found in domestic cats and their larger relations, the cheetah and the puma, in eland and nyala, and in the gemsbok and the Arabian oryx. In the United States, mink have been affected by it. The infective agent and its mode of transmission are unknown, but the evidence from kudu suggests that some species may be more easily infected than others. Sheep are believed to catch the disease by contact with placentas in fields after births, but in the case of the kudu even this route seems unlikely. In THE VETERINARY RECORD, the scientists eliminate most routes of infection. Infected feed cannot account for four cases. Nor can at least three of the affected animals have caught the disease from their mothers, who did not suffer from it. It is possible but unlikely that the mothers were carriers that passed on the infection without having symptoms themselves. If this were so, it would have important implications for the disease in cows. It is more likely, the scientists believe, that an unidentified agent entered the herd in contaminated feed and was passed along, as with more mundane infections. Because of the danger to other animals, the kudu herd has been isolated. Another danger taken seriously by the zoo, a world centre for breeding rare and endangered species, is that animals bred in captivity could carry the infection when released into the wild. If they proved as vulnerable as the kudu, this could be disastrous. The scientists say that the next step must be to examine whether the agent causing the disease in kudu is the same as that in cows. If it is, the conclusion would be that the kudu were simply more susceptible to the disease. If, however, it turned out to be a different and more easily transmittable form, the case for isolating the kudu would be even stronger. TIMES NEWSPAPERS LIMITED, 1993
affected animals;mad cow disease;london zoo;similar transmission;kudu herd;endangered species