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At least 19 recordsLinked to original sources

Pathogenesis of abortion of bovine brucellosis.

Bovine brucellosis is a major disease of cattle characterized by abortion during the last trimester of gestation. During many years important pieces of research have been done looking for a better understanding of this particular phenomenon. Yet, the fact that the abortion takes place in the last period of gestation result in a fascinating interrogant for such a unique event. The present review includes most of the information available regarding to this matter. Emphasis is done in the interaction of Brucella abortus with the trophoblastic cells of the bovine placenta.

Abortion, Veterinary↗

Evaluation of three LPS-specific monoclonal antibodies for the immunodiagnosis of bovine brucellosis.

Bovine sera collected during the Australian brucellosis eradication campaign were used to assess the value of three monoclonal antibodies (MAb Bruce 1, 4 and 7) for the immunodiagnosis of bovine brucellosis in a competitive enzyme immunoassay (CEIA). Each MAb reacted to a different epitope of lipopolysaccharide molecules on the cell surface of Brucella abortus. When the sensitivity of the CEIA was set at 100 per cent so that all infected animals were identified, the specificity of the test using MAb Bruce 1 and Bruce 7 was 69 per cent and 52 per cent, respectively. On the other hand, a quarter of the sera from infected cattle did not inhibit the binding of MAb Bruce 4 to the antigen. With a maximum sensitivity of 75 per cent, the specificity of the CEIA using MAb Bruce 4 was 94 per cent. However, all three MAb cross reacted with sera from sheep infected with Bovis, Histophilus ovis and Actinobacillus seminis.

Animals↗

[Clinical and epidemiological aspects of bovine brucellosis in tropical Africa].

Bovine brucellosis, in the tropical regions of Africa, is very different, both clinically and epidermiologically, from that observed in temperate zones. From the clinical point of view, abortion is rare and extra-genital lesions (hygromas and abscesses) are frequent. From the epidemiological point of view, the rate of infection is low and the disease has very little tendency to spread. The reason for these differences may be explained by climatic conditions (temperature, insolation, humidity) as well as by breeding conditions (principally nomadic or transhumant breeding). Where climatic and breeding conditions resemble those of intensive breeding in temperate zones the clinical and epidemiological aspects tend towards similarity with the usual form of bovine brucellosis.

Abortion, Veterinary↗

Evaluation of an indirect ELISA for the diagnosis of bovine brucellosis.

Control and eradication of bovine brucellosis is usually based on the serological detection of antibodies. In Argentina, the rose bengal test (RB) and the buffered plate antigen test (BPA) are the 2 screening tests officially recognized, whereas the 2-mercaptoethanol test (2ME) and the tube agglutination test (SAT) are the confirmatory assays currently in use. In order to improve the serological diagnosis of bovine brucellosis in Patagonia, Argentina, an indirect enzyme-linked immunosorbent assay (I-ELISA) kit distributed by the International Atomic Energy Agency was evaluated. Sera from negative nonvaccinated, negative but vaccinated, and positive animals were tested by all the above techniques. The specificity of the I-ELISA (98.9% and 97.2%) was similar to that of the BPA, RB, 2ME and complement fixation (CF) tests when used to test sera from negative nonvaccinated and negative but vaccinated animals, respectively. The sensitivity of the I-ELISA (98.7%) was higher than the BPA test (96.1%) and the CF test (95.2%). The I-ELISA kit evaluated in this study was thought to be a valuable tool for the diagnosis of bovine brucellosis in the Patagonia region where little epidemiological information is available about this disease, and where large numbers of sera should be tested to obtain such information.

Agglutination Tests↗

Comparison of the results of some serological tests for bovine brucellosis.

A total of 1887 bovine sera positive to the Rose Bengal plate test were subjected to other serological tests for bovine brucellosis: the complement fixation test using warm fixation (CFTW),the serum agglutination test (SAT) and the radioimmunoassay (RIA). The SAT was generally much less sensitive than the CFTW. Many sera, however, gave positive reactions in the SAT but no reaction in the CFTW or the RIA. These SAT reactions were attributed to IgM antibody. Comparison between the results of the CFTW and the RIA led to the conclusion that 200 ng could be used as a minimum diagnostic reaction in the RIA.

Agglutination Tests↗

Examination of lochia as an aid to the early diagnosis of bovine brucellosis.

The standard technique for diagnosing bovine brucellosis is the serological examination of blood samples. As affected females may excrete large numbers of the Brucella organism in the lochia, the bacteriological and smear examination of such material appeared to be a suitable alternative for early diagnosis. Of the lochia samples collected from 210 cows and heifers within 12-24 h after parturition or abortion, 10.9% were bacteriologically positive. Only 70% of these could be diagnosed correctly as positive by microscopic examination. This technique also resulted in 3.3% false negative and 1.4% false positive diagnoses. Results of the serological examinations of blood, collected simultaneously with the lochia samples, correlated fairly well with those obtained microscopically. Culture of lochia samples on a suitable medium appears to be the method of choice, when dealing with the early diagnosis of bovine brucellosis.

Animals↗

Recent developments in vaccination against bovine brucellosis.

Recent research in vaccination against bovine brucellosis has been directed towards reducing the serological response to vaccination and to developing serological tests better able to distinguish vaccinal titres from those resulting from field infection. In the case of strain 19 vaccination, developments such as reducing the dose of vaccine and improving serological tests have so reduced the serological response as to allow adult vaccination to be carried out in combination with eradiction by test and slaughter. B. abortus 45/20 vaccine is being increasingly used as a combined diagnostic aid and protective agent. Progress has been made in identifying antibodies produced in response to this vaccine.

Agglutination Tests↗

Isolation of brucella abortus from two dogs in contact with bovine brucellosis.

On a farm where several cattle were serologically positive for bovine brucellosis, three dogs were found to have titres greater than 400 i.u. to Brucella abortus. The titres persisted until the dogs were killed over two months later. Two male dogs were necropsied. B. abortus was isolated from the spleen of both dogs. While farm dogs are not thought to be a major reservoir of bovine brucellosis they may be considered as possible carriers in imfected herds and should be considered during the investigation and eradication of bovine brucellosis.

Animals↗

How to substantiate eradication of bovine brucellosis when aspecific serological reactions occur in the course of brucellosis testing.

Collaborative work was financed by the EU to develop and assess new diagnostic tools that can differentiate between bovine brucellosis and bovine infections due to Yersinia enterocolitica O:9 either in conjunction with, or as an alternative to, the classical serological, bacteriological or allergic skin tests. Sixteen heifers were experimentally infected with Brucella abortus biovar 1 (five heifers), Brucella suis biovar 2 (two heifers), Y. enterocolitica O:9 (six heifers) and Y. enterocolitica O:3 (three heifers). Four heifers, naturally infected with Y. enterocolitica O:9 that presented aspecific brucellosis serological reactions were also included in the experiment. A self-limited infection was induced in cattle by B. suis biovar 2. All the brucellosis serological tests used, i.e. the slow agglutination test (SAW), the Rose Bengal test (RB), the complement fixation test (CFT), indirect and competitive ELISA's, lacked specificity when used to analyze sera from Y. enterocolitica O:9 infected animals. A Yersinia outer membrane proteins (YOPs)-ELISA was also used and although the test is able to detect a Yersinia group infection, it provided no evidence of whether or not there is a possible brucellosis infection when dual infections are present. The brucellergen IFN-gamma test showed a lack of specificity also. The only test that was proven to be specific is the brucellergen skin test. All brucellosis serological tests, except the indirect ELISA, were limited in their ability to detect B. abortus persistently infected animals. Based on these experimental studies, a strategy was implemented as part of the year 2001 Belgian Brucellosis Eradication Program to substantiate the eradication of bovine brucellosis. Epidemiological inquiries have identified risk factors associated with aspecific serological reactions, possible transmission and infection of cattle by B. suis biovar 2 from infected wild boars; and both legal and administrative measures taken by the veterinary services. No cases of bovine brucellosis have been confirmed in Belgium since March 2000.

Animals↗

Application of an enzyme-linked immunosorbent assay in the final stages of a bovine brucellosis eradication program.

Bovine field serums from the Australian brucellosis eradication program were used to compare 2 enzyme linked immunosorbent assays (ELISA) with the complement fixation test (CFT) and Rose Bengal test (RBT). One ELISA used an anti-bovine IgG horseradish peroxidase conjugate (ELISA 1) and the other a monoclonal anti-bovine Ig alkaline phosphatase conjugate (ELISA 2). When compared with the CFT, the ELISA 2 like the ELISA 1 lacked specificity in B. abortus vaccinated herds but the ELISA 2 was more specific than the ELISA 1 in previously infected herds and equally as specific as the ELISA 1 in nonvaccinated Brucella free herds. In this study the ELISA 2 proved more sensitive than the CFT, RBT and ELISA 1 particularly in herds where B. abortus biotype 2 was present. The value of using the ELISA 2 in conjunction with the CFT in an eradication program is discussed.

Agglutination Tests↗

Applied serology in the latter stages of the eradication of bovine brucellosis.

Late in the program to eradicate bovine brucellosis from Western Australia, Rose Bengal test (RBT) and complement fixation test (CFT) results on the serums from 2,307 cattle (from herds where infection was still present after a minimum of 3 complete herd tests) showed that 327 were positive in the CFT and 246 were positive in the RBT (p less than 0.001). Subsequent testing by the RBT, CFT and the indirect haemolysis test (IHLT) of 722 serums from cattle slaughtered as part of infected herds showed that of 177 cattle positive on culture, 138 were positive in all 3 tests, 9 were negative in all 3 tests and no animal positive on culture had a reaction only in the RBT. In the 177 cattle from which B. abortus was isolated, positive reactions in the CFT occurred in the serums of 159 of them. Application of the RBT as a screening test followed by a confirmatory CFT would have resulted in 149 of the 177 cattle being positive and application of the CFT/IHLT (double test) on the serums of all cattle in the herds would have resulted in 168 or the 177 being regarded as positive.

Animals↗