A cross-sectional cattle disease study in Kongor rural council,southern Sudan. I. prevalence estimates and age,sex and breed associations for brucellosis and contagious bovine pleuropneumonia

A cross-sectional study was designed to investigate the prevalence of bovine brucellosis and contagious bovine pleuropneumnia (CBPP) in Kongor Rural Council, southern Sudan and to assess associations between the presence of antibodies for these diseases with age, sex and breed. The detection of Brucella antibodies using the Rose-Bengal plate test was significantly associated with increasing age. The difficulty of estimating the true prevalence of brucellosis from the apparent prevalence based on test results is disscussed. Although no linear association between age and CBPP complement fixation test results were found, cattle of 2–4 years of age appeared to be at higher risk. Local factors important in CBPP disease control planning are discussed.     

Evaluation of a delayed-type hypersensitivity test for the diagnosis of Brucella abortus infection in cattle

The delayed-type hypersensitivity (DTH) test was used to diagnose brucellosis in two cows experimentally induced with brucellosis, and 176 dairy cows from a farm suspected of brucellosis. DTH test results were compared with results of the milk ring test, the serum agglutination test, the complement fixation test and the Coombs test. Cows positive in the DTH test and in one of the other tests were examined bacteriologically. In experimentally infected animals the DTH test was positive 10 days after infection, 1-4 weeks before serologic tests indicated brucellosis. Although the DTH test was positive during the whole experiment, on the one occasion when serologic titres were high, it was negative. Of the 176 dairy cows, 45 were positive in one or more serologic tests. In twelve cows (29%) the diagnosis was inconclusive because they were positive in only one of the serologic tests. In these cases the DTH test confirmed the infection. Three cows with high serologic response tested negative in the DTH test. B. abortus was isolated from 13 of 15 cows examined. We conclude that when serologic results are ambiguous, the DTH test is a useful additional technique for diagnosing brucellosis.     

An evaluation of the delayed-type hypersensitivity test for diagnosing brucellosis in individual cattle: a field study

A field study was conducted to evaluate the delayed-type hypersensitivity (DTH) test in diagnosing brucellosis in cattle, in particular the diagnosis of infection in individual cows. A total of 93 cows that were negative, suspect, or positive to the serum agglutination test (SAT), complement fixation test (CFT), or the milk ring test (MRT) were subjected to the DTH test. The cows were then slaughtered and the supramammary lymph nodes were collected for bacteriologic examination. In 989 cows the DTH test, MRT and serologic tests were negative. When the DTH test results were compared with bacteriologic results, 12 of the 93 cows with CFT titres greater than 1:200 tested negative in the DTH test while bacteriologic results were positive. The sensitivity of the DTH test (calculated on the remaining 81 cows) was 100%; the specificity was 83%. The sensitivity of the DTH test (calculated on 93 cows) was 81%; the specificity was 83%. The sensitivity and specificity of the DTH test correlated well with those of the CFT (86-83%). We conclude that the DTH test is very sensitive, and specific enough to diagnose brucellosis in individual cows. The DTH test should be used in combination with serologic tests in the diagnosis of brucellosis.     

奶牛布鲁氏菌病的诊断与防控

奶牛布鲁氏菌病主要是由牛种布氏杆菌（又称流产布氏杆菌）感染引发,在畜牧业中具有极高的关注度。这种疾病的病症表现多样,感染后的奶牛可能出现流产、死胎、胎盘滞留等现象,同时还可能伴随着关节炎、乳腺炎等疾病。与此同时,该病是一种人畜共患的传染病,病菌主要通过消化道、呼吸道和生殖道传播,对于奶牛养殖者而言,及时发现和诊断奶牛布鲁氏菌病至关重要。本文将详细探讨奶牛布鲁氏菌病的特性与症状、诊断与检测、防控原则与措施。     

Milk yield and reproductive performance of brucellosis-vaccinated but seropositive Holstein cows

The aim of this research was to study if seropositivity for brucellosis in vaccinated cows against this disease hampers reproductive performance and milk production in high-yielding Holstein cows. For this purpose 1,026 healthy cows and 372 cows seropositive for brucellosis were enrolled in this study. Cows positive to card test and subsequently to the rivanol test were further subjected to the radial immunodiffusion (RID) test. It was found that only 11 % of the presumably infected cows by brucellosis screening tests were really infected with this disease. The reproductive performance of the group of cows with 11 % Brucella-infected animals was not impaired; overall pregnancy rate did not differ between seropositive and healthy cows (30.9 vs. 29.6 %). The abortion rates were similar between seropositive cows (5.3 %) and seronegative animals (6.9 %). Cows in the herd with 11 % Brucella-infected animals produced significantly more milk than unaffected cows over a 305-day lactation (10,684?±?1,720 vs. 10,345?±?1,736; mean ± SD; P?<?0.05). It was concluded that in dairy herds vaccinated against brucellosis with both 19 and RB51 strains, supplemental tests such as RID need to be conducted on all reactors in order to maintain diagnostic accuracy. These results also indicate that 11 % animal prevalence of brucellosis did not exert a detrimental effect on 305-day milk yield and reproductive performance in high milk-yielding Holstein cows.     

The use of a brucella protein antigen in dermal hypersensitivity as an adjunct method to diagnose bovine brucellosis

A total of 191 cows in 3 herds were injected with a brucella protein antigen in an effort to compare serologic and bacteriologic findings with delayed hypersensitivity and to possibly detect incubative brucellosis. Using cultural and serologic results, the responses to the BPA antigen were inferior to serologic tests in the diagnosis of infection. None of the 23 skin test positive/seronegative cows were positive on subsequent herd blood tests.     

Intracellular trafficking study of a RB51 B. abortus vaccinal strain isolated from cow milk

Brucella is responsible for one of the major worldwide zoonoses. Over the last century, several vaccines have been used against brucellosis. Among these, the rough vaccine Brucella abortus RB51 was introduced with the idea that it would not interfere with the diagnosis of brucellosis. Recently, RB51 has been isolated from milk and vaginal exudates from vaccinated cows, thus raising the possibility of extensive bacterial replication in these animals. We hypothesized that shedding of RB51 might be related to a change in its intracellular cell cycle. Therefore, we have compared the intracellular trafficking in CHO cells of the virulent B. abortus 2308 and two RB51 strains, the vaccinal strain and the one isolated from cow milk. Both RB51 strains were transiently observed in phagosomes characterized by the presence of the early endosomal marker EEA1 and then were found in cathepsin D-enriched lysosomal compartments, in which they eventually underwent degradation at later post-infection times. In contrast, the virulent 2308 strain replicated within the endoplasmic reticulum. These results suggest that a change in intracellular trafficking cannot account for Brucella shedding in adult vaccinated cows.     

我国奶牛布鲁氏菌病防控的现状与防控措施

布鲁氏菌病是一种人畜共患传染病,世界动物卫生组织将其列为B类动物疫病.病牛可通过其产品和代谢产物排出病原菌,感染人和其他动物,引起其他动物发病.国家对奶牛布鲁氏菌病的防控投入了大量的人力、物力,但收效甚微.近年来,不断有人感染布病的报道出现.笔者根据多年的工作体会,对当前我国奶牛布鲁氏菌病的防控做了现状分析,并提出一些对策供大家参考.     

Correlation of field strain exposure with new cases of brucellosis in six beef herds vaccinated with strain 19

Three hundred sixty cattle at risk in 6 beef herds known to include cows infected with Brucella abortus field strains were vaccinated with 3 x 10(9) colony-forming units of strain 19. Field strain exposure after vaccination was estimated by the number of cows with brucellosis that calved or aborted in the herd. As the number of exposures increased, the number of cows developing brucellosis increased, and 19 exposures in the 6 herds resulted in 9 new cases. The ratio of exposures to new cases varied from 1.0 to 2.0 in the 4 herds with new cases, whereas 2 herds with 1 and 3 exposures, respectively, did not have new cases of brucellosis. The correlation coefficient between the number of exposures and the number of new cases was 0.85, and the coefficient of determination suggested that 73% of the variation in new cases could be explained by the number of exposures in strain 19-vaccinated herds.     

Lungworm disease in dairy cattle: symptoms,diagnosis, and pathogenesis on the basis of four case reports

Clinical lungworm disease appears to occur frequently in Dutch dairy herds. Because the clinical diagnosis is difficult to make in adult cattle, the clinical diagnosis, laboratory diagnosis, differential diagnosis, therapy, and prevention are discussed in this article. In addition, four cases of lungworm disease in adult cattle are presented. The main clinical complaints were coughing, decreased milk production, and weight loss. Several lactating cows died in one herd. The disease history of four herds revealed that introduction of susceptible cows or heifers to herds with cows with subclinical patent lungworm infections had resulted in a pasture infection, leading to clinical problems in both the newly introduced and 'resident' cows of the herd. Further history analysis of the fourth herd revealed that re-introduction of lungworm infection by newly purchased cows in a lungworm free herd resulted in clinical lungworm problems in adult and young animals. The fourth case led to the conclusion that lungworm infection must have been re-introduced by cows purchased from another farm.     

Enzyme immunoassay using mouse monoclonal anti-bovine antibodies for the detection of Brucella abortus antibodies in cow milk

Individual milk samples and artificially constructed tank milk samples from cows with naturally occurring brucellosis were examined by the enzyme-linked immunosorbent assay (ELISA) using sonicated B. abortus S-99 antigen, and mouse monoclonal anti-bovine IgM, IgA, and IgG1 conjugates. ELISA results were compared with the results of the milk ring test using either 1 ml milk (MRT-1) or 8 ml milk (MRT-8). The ELISA using mouse monoclonal anti-bovine IgG1 conjugate was sensitive and specific. In testing individual milk samples and constructed tank milk samples containing milk with low titers in the MRT-1 the ELISA was superior to the MRT-1, and MRT-8. In testing other milk samples, the ELISA was as sensitive or slightly less sensitive than the MRT-8. From a total of 5,910 milk samples collected from cows free from brucellosis, only 24 (0.4%) samples tested positive in the ELISA. All 500 tank milk samples collected from farms negative for brucellosis tested negative in the ELISA. We concluded that the ELISA is a good substitute for the MRT-1 to detect antibodies against Brucella in milk from individual cows. When tank milk is tested for antibodies against Brucella, however, both the MRT-8 and the ELISA should be used.     

A simulation model of intraherd transmission of foot and mouth disease with reference to disease spread before and after clinical diagnosis.

Intraherd transmission of foot and mouth disease virus (FMDV) was examined using a simulation model for a hypothetical 1,000-cow dairy, assuming clinical diagnosis was made when at least 1% (10 cows) or 5% (50 cows) had clinical signs of FMD, I index case cow, and transition state distributions for the latent, subclinically infectious, and clinically infectious periods of FMD calculated from published data. Estimates assumed for the number of animal-to-animal contacts (k) adequate for transmission ranged from 0.6 to 9.0 per hour (13.7-216.0 per day). A total of 40,000 iterations (5,000 for each scenario, assessing 4 adequate contact rates and 2 detection criteria) were run. The model predicted that FMD would not be diagnosed in the herd until 10.0-13.5 days after the index case cow had become infected, at which time between 65% and 97% of the cows (646-967 cows) to nearly 100% (978-996 cows) would already have become infected with the virus, if the number of cows showing clinical signs of FMD at the time of diagnosis were 10 or 50, respectively. At the time of diagnosis, the simulated number of infectious cattle varied substantially from 82-472 to 476-537 cows, depending on adequate contact rate and whether the diagnosis was made when 10 or 50 animals were showing clinical signs, respectively. The simulated number of infectious cows increased rapidly during the first few days after diagnosis. In the scenario where at least 10 cows showing clinical signs was necessary before a clinical diagnosis was made, each day after diagnosis, the number of infectious animals increased by nearly 100 to more than 200 cases per day up to day 5, assuming 0.57-9.0 animal-to-animal contacts per hour, respectively. Results obtained when it was assumed that at least 50 clinical cases were present at the time of diagnosis showed smaller relative increases because nearly one-half of the herd was projected to be infected at the time of diagnosis. From these results, it is clear that once an individual in a herd becomes infected with FMDV, herd infectivity is not static, rather it accelerates as would be expected as long as there are sufficient susceptible animals to sustain the increasing transmission rate, after which time the rate at which new infections occurs will diminish. Results indicate that biosecurity strategies aimed at minimizing both intraherd and interherd contact will be critical in minimizing the spread of FMD before the initial diagnosis is made. In addition, simulations suggest that very early clinical diagnosis of FMD and effective isolation or depopulation and disposal will be critical in limiting the number of infectious animals capable of transmitting the virus to other herds and thus in timely control of an epidemic. Early diagnosis will rely on early virus detection from animals in the preclinical phase of infection, rather than waiting for clinical signs to manifest in sufficient numbers to be noticed and to warrant investigation.     

奶牛布氏杆菌病的血清学调查及分析

为了解奶牛布氏杆菌病的流行情况,及时消灭传染源,切断传播途径,2007年对本辖区的所有奶牛进行血清学调查。主要采用虎红平板凝集试验进行初筛,出现阳性及可疑再用试管凝集试验作进一步确诊。监测结果显示:对本辖区监测的724份奶牛血清样品中,平均阳性率为7.73%,阳性奶牛全部进行了扑杀并作无害化处理;布病在本辖区的个别奶牛场中阳性率高,在今后的一定时期内,需采取进一步的监测净化防控措施。     

Comparison of an indirect ELISA with the Brucella milk ring test for detection of antibodies to Brucella abortus in bulk milk samples.

An indirect enzyme-linked immunosorbent assay (ELISA) for the detection of Brucella abortus antibodies in bovine bulk milk samples was evaluated. About 31 individual milk samples from B. abortus infected cows were diluted into bulk milk from a brucellosis free herd. Individual milk samples obtained from 96 negative or positive herds to ELISA or Brucella ring test (BRT), were tested by ELISA. All positive cows were bled and serum samples were tested by the complement-fixation test (CFT) which was considered the definitive test. A herd was considered infected if at least, one cow was positive in the CFT. Four samples were negative in the BRT at the dilution 1:10 but positive in the ELISA. For samples positive in both tests, BRT titers ranged from 1:10 to 1:480 while ELISA titers ranged from 1:10 to 1:3200.Using bulk milk samples, the sensitivity of the ELISA (98.1%) was higher than the BRT (72.2%) but the specificity of BRT (90.5%) was not statistically different (P=1.0) from the ELISA (88.1%). The implications of the results for brucellosis control are discussed.     

高原奶牛布鲁氏菌病的血清学调查

为了解青海省民和县奶牛布鲁氏菌病的分布和流行情况,净化布鲁氏菌病,对来自12个乡镇的10308份奶牛血清采用试管凝集反应试验(SAT)进行了血清学检测,检出阳性血清23份,阳性率为0.223%,表明青海民和地区存在奶牛布鲁氏菌的感染。     

Epidemiology of bovine brucellosis in the coastal region of Baja California Norte, Mexico: Results of path analyses in an area of high prevalence

Data for path analysis on the epidemiology of bovine brucellosis were collected on 110 premises in the Coastal Administrative Region of Baja California Norte, Mexico. Two structural models were used to identify the significant contributory variables on the bovine brucellosis seropositivity. The first model identified six variables significantly related to seropositivity for bovine brucellosis, and the second model identified five such variables, four of which were the same in both models. These four variables are (1) capital invested in livestock, (2) number of animals eligible for testing, (3) the policy of the owner/manager in regard to the disposal of reactor (infected) animals and (4) the number of cows that aborted in the previous year. Preliminary serotesting revealed this to be an area of relatively high prevalence. The significant contributory variables found in this analysis are compared to a previous and identical analysis on data collected in Mexicali Valley, Mexico, an area with low prevalence and with different herd sizes and management styles.     

Seroprevalence and risk factors for bovine brucellosis in Jordan

We investigated the seroprevalence and risk factors for Brucella seropositivity in cattle in Jordan. The sera from 671 cows were randomly collected from 62 herds. The antibodies against Brucella were detected using a Rose Bengal plate test and indirect ELISA. A structured questionnaire was used to collect information on the cattle herds'' health and management. A multiple logistic regression model was constructed to identify the risk factors for Brucella seropositivity. The true prevalence of antibodies against Brucella in individual cows and cattle herds was 6.5% and 23%, respectively. The seroprevalence of brucellosis in cows older than 4 years of age was significantly higher than that in the younger cows. The seroprevalence of brucellosis in cows located in the Mafraq, Zarqa and Ma''an governorates was significantly higher than that of the other studied governorates. The multiple logistic regression model revealed that a larger herd size (odd ratio = 1.3; 95% CI: 1.1, 2.6) and mixed farming (OR = 2.0; 95% CI: 1.7, 3.7) were risk factors for cattle seropositivity to Brucella antigens. On the other hand, the use of disinfectants (OR = 1.9; 95% CI: 1.1, 2.1) and the presence of adequate veterinary services (OR = 1.6; 95% CI: 1.2, 3.2) were identified as protective factors.     

临夏州奶牛布鲁氏菌病的监测结果与分析

为了全面了解和掌握临夏州动物布病布鲁氏菌病感染和流行状情况,有效制定防控对策,确保人民群众身体和草食畜牧业的健康发展,于2015—2018年笔者对临夏州8县(市)开展奶牛布鲁氏菌病检测。通过实验室检测,对阳性畜及时扑杀,以检测扑杀相结合到逐步达到净化的目的。     

Differential reactivity of bovine lymphocytes to species of Brucella

The reactivity of bovine lymphocytes to 4 species of Brucella was tested in thymidine-uptake assays, using long-term cultured lymphocytes and freshly obtained blood mononuclear cells. Lymphocytes were taken from cows that had been challenge exposed with a virulent strain of B abortus at midgestation. The cows were classified retrospectively as being naturally resistant or susceptible to brucellosis. Lymphocytes taken from these cows had 3 patterns of reactivity with species of Brucella: pattern 1 was defined by reactivity with 4 species (B abortus, B canis, B suis, and B melitensis); pattern 2 was defined by reactivity with all these species, except B melitensis; pattern 3 was defined by reactivity with B abortus and B canis, but not with B suis or B melitensis. There was a statistically significant correlation between susceptibility to brucellosis and expression of lymphocyte cross-reactivity with B suis (P less than 0.01) and with B melitensis (P less than 0.001).     

The use of a single complement fixation test technique in bovine brucellosis, Johne's disease, dourine, equine piroplasmosis and Q fever serology

The same techniques may be used in the complement fixation test (CFT) for the serological diagnosis of bovine brucellosis, Johne's disease (paratuberculosis), dourine, equine piroplasmosis and Q fever (caused by Coxiella burnetii). The reproducibility of results is excellent, falling for the most part within the twofold range and never exceeding the fourfold range. Agreement with other laboratories is excellent (i.e. within twofold) in the case of brucellosis and equine piroplasmosis antibody titres. A good correlation between the occurrence of the disease and serological reactions is found on circumstantial evidence in the cases of dourine, Johne's disease and Q fever. A standard unitage system is used to report the antibody titres found in all the tests. To simplify laboratory protocols, laboratories required to employ the CFT for the diagnosis of these diseases are advised to use a single proven technique in all the tests. Problems experienced with transient false-positive Johne's disease antibody titres in cattle following on tuberculin (bovine and avian) testing make it advisable to take specimens for the Johne's disease test prior to performing the tuberculin tests.