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Two strains of bovine Theileria from northern Nigeria were shown to be identical to Theileria mutans in the indirect immunofluorescent antibody test. One of the strains was transmitted by the tick Amblyomma variegatum; large macroschizonts, typical for T mutans, could be demonstrated in infected cattle. It is concluded from these experiments and from the literature that there is reliable evidence so far for the occurrence in Nigeria of only two bovine Tehileria species, T mutans and T velifera. 相似文献
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Schreuder BE 《Tijdschrift voor diergeneeskunde》1999,124(6):182-184
After a discussion of the different hypotheses about the causative agent of prion diseases, various aspects of the two most important animal prion diseases, i.e. BSE and scrapie are described. This thesis focuses on the search for a preclinical diagnosis. A major breakthrough was the discovery of a new technique for detecting the disease-associated protein in tonsillar biopsies from scrapie-infected sheep long before clinical signs appeared. Another essential part of the studies described in this thesis concerned a risk analysis for BSE in a country like the Netherlands. Major risk factors were assessed, including an assessment of the efficacy of Dutch rendering procedures in the inactivation of the agents of scrapie and BSE. 相似文献
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G.?L.?GadburyEmail author H.?K.?Iyer H.?T.?Schreuder 《Journal of Agricultural, Biological & Environmental Statistics》2002,7(1):42-57
In this article, we propose an adaptive procedure for testing for the effect of a factor of interest in the presence of one or more confounding variables in observational studies. It is especially relevant for applications where the factor of interest has a suspected causal relationship with a response. This procedure is not tied to linear modeling or normal distribution theory, and it offers a valuable alternative to traditional methods. It is suitable for applications where a factor of interest is categorical and the response is continuous. Confounding variables may be continuous or categorical. The method is comprised of two basic steps that are performed in sequence. First, confounding variables alone (i.e., without the factor of interest) are used to group observations into subsets. These subsets have the property that, when restricted to a subset, there is little or no remaining variation in the response that is attributable to the confounding variables. We then test for the factor of interest within each subset of observations. We propose to implement the first step using a technique that is generally referred to as tree-structured regression. We use a non parametric permutation procedure to carry out the second step. The proposed method is illustrated through an analysis of a U. S. Department of Agriculture (USDA) Forest Service data set and an air pollution data set. 相似文献
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Five sheep, free from Mycoplasma conjunctivae and ocular Chlamydia infection, were experimentally inoculated with M. conjunctivae and five more sheep were exposed to the infection by contact. Keratoconjunctivitis developed in all ten sheep. As in natural outbreaks of infectious keratoconjunctivitis (IKC), clinical signs were generally moderate and transient, and recurred in some sheep. M. conjunctivae was detected throughout the 53-day observation period. Clinical diagnosis was confirmed by histopathologic examination of three sheep. Moraxella ovis, found in six of the ten sheep before the start of the experiment, appeared to play no etiologic role in the development of IKC. 相似文献
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Incidence of indurative lymphocytic mastitis in a flock of sheep infected with maedi-visna virus 总被引：1，自引：0，他引：1
D J Houwers J J Pekelder J W Akkermans E J van der Molen B E Schreuder 《The Veterinary record》1988,122(18):435-437
Sheep in a flock in which 88 per cent of the ewes had antibodies to maedi-visna virus were clinically examined for udder induration during lactation and after drying off. On both occasions about half of the ewes had indurated udders. Histological examination revealed lymphocytic mastitis associated with maedi-visna virus infection, in the udders of six of 25 hoggs (24 per cent), 21 of 39 shearlings (53.8 per cent) and 42 of 67 ewes (62.7 per cent). Distinct lung lesions were found in 8 per cent of the hoggs, 12.5 per cent of the shearlings and 10 per cent of the ewes. The results of a clinical examination of dry udders were correlated with the histological findings. 相似文献
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B.E.C. Schreuder 《The Veterinary quarterly》2013,33(3):182-192
Summary An update on animal spongiform encephalopathies other than BSE was presented in part I of this article. Part II of this article focuses on bovine spongiform encephalopathy (BSE). The article describes clinical signs, histological and other changes leading to a diagnosis, the differential diagnosis, and the prospects for pre‐clinical diagnosis of this disease. It describes the origin and course of the epidemic in the UK and discusses the question why it is only the UK which has witnessed such a large‐scale epidemic. Predicted to arrive much earlier, the epidemic now finally seems to have passed its peak. The article goes on to discuss the chance of the disease occurring in a country like the Netherlands and the measures taken to prevent and control the disease, should it occur. The article concludes with a discussion of what has been found with regard to genetic factors, the results of experimental and unintentional artificial transmission of BSE to various species, and possible implications for human health. 相似文献
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It is only in the last 5 years that the Netherlands has been confronted with cases of bovine spongiform encephalopathy (BSE). The cases diagnosed to date have not been clearly linked to imports from the United Kingdom. This article describes the various possible explanations for the Dutch cases. The risk factors involved, have either a connection with imported BSE, local origin of BSE, or both. These factors can also be divided into introductory risk and propagation risk, terms that were also used in an EU risk assessment study. Research at ID-Lelystad since the early 1990s and at IKC-Ede has tried to assess the relative importance of the various risk factors, the results of which are discussed in this paper. The paper does not deal with the specifics of the cases diagnosed to date, because of the absence of an in-depth epidemiological investigation, but provides a general assessment of the risk factors that might have played a role. Important factors have been, in addition to the initial imports of cattle and meat and bone-meal from the UK, the continuing imports from other countries with covert BSE and the cross-contamination within the animal feed production lines. Emphasis is on the period of the early and mid-1990s, the period in which most calves with diagnosed BSE were born. 相似文献