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Experimentally-induced cases of sweating sickness in calves were used in an effort to correlate the blood chemistry with some of the known pathological changes. Results showed that the "sweating" associated with necrotic dermatitis did not alter blood electrolyte levels. Laboratory evidence of a disseminated intravascular coagulopathy was found which(More)
We became increasingly concerned about indications of possible substandard efficacy of some generic anthelmintics, particularly after P.C. van Schalkwyk (personal communication, 1990) had found some batches of imported generic products obtained from international brokers to be poorly active, despite apparently normal physical characteristics. Therefore,(More)
Antibodies in the sera of domestic ruminants that have been infected with Ehrlichia bovis and other ehrlichial agents cross-react with the Kümm strain of Cowdria ruminantium used in the indirect fluorescent antibody test as antigen. These cross-reactions are also shown by the Elisa test in which the Ball 3 strain of the heartwater agent is used as antigen.
An ELISA was developed using an SDS extract of Brucella abortus as antigen to detect antibodies in cattle sera. The antigen was stable at 4 degrees C for at least 4 years and although it gave optimal results at a 1/4,000 dilution it could detect reactors at a 1/32,000 dilution. Based on comparative CF tests on 430 sera from negative herds and 187 sera from(More)
A quantitative study of the changes in the protein pattern of the salivary glands of female Rhipicephalus evertsi evertsi during the entire repletion process was undertaken. These results, in conjunction with the previously determined toxic phase, indicated the presence of a toxic protein. The development of a sensitive in vitro assay using a Xenopus(More)
The isolation of Cowdria ruminantium by means of wheat germ lectin affinity chromatography as described in this paper permits the recovery of partially purified viable organisms under mild conditions in short time. These conclusions are based upon results of analyses of column fractions by intravenous inoculation into sheep, protein determination,(More)
Investigation into the presence of C. ruminantium antigen, using an enzyme-linked immunosorbent assay (ELISA) in various tick tissues and haemolymph of adult Amblyomma hebraeum ticks revealed that the organism invades a number of body parts and can be demonstrated in A. hebraeum. In females, the gut, salivary glands, hypodermis and synganglion and in males,(More)
The presence of endotoxin was examined in 5 sheep with experimentally-induced heartwater. Two peaks in endotoxin levels were recorded in 4 out of the 5 sheep during the acute stage of the disease. The 1st peak coincided with or occurred shortly after the febrile reaction (over 40 degrees C). The 2nd peak occurred 3-5 days after the 1st, and in 2 sheep this(More)
The events leading to the production of an effective vaccine against heartwater are summarized. The production techniques used at Onderstepoort to produce and control the quality of the infected blood and nymph suspension vaccines, and covering their respective advantages and disadvantages, are compared. The many problems of these vaccines and how they may(More)