Assessment of milk ring test and some serological tests in the detection of <Emphasis Type="Italic">Brucella melitensis</Emphasis> in Syrian female sheep

Brucella melitensis infection prevalence among Syrian female sheep, to evaluate a number of serological tests and to discuss some epidemiological aspects of brucellosis, was studied. A total of 2,580 unvaccinated Syrian female sheep sera samples were tested for B. melitensis antibodies detection using four serological methods: the Rose Bengal test (RBT), the serum agglutination test (SAT), the complement fixation test (CFT) and an indirect enzyme-linked immunosorbent assay (iELISA). In addition, 2,375 milk samples were collected, then milk ring test (MRT) and bacterial isolation test were employed to evaluate the natural organism shedding. The samples were considered positive in 66%, 64%, and 60% when we employed the RBT, SAT, and iELISA tests, respectively. Whereas, the CFT test revealed the smallest number of positive samples. By using the MRT, the total prevalence of brucellosis was nearly 38% of samples. A large variation was observed concerning the studied areas, ranging from 24% in Tartous to 44% in both Damascus and Damascus rural areas. Brucella was isolated from only 677 samples out of the 2,375 female sheep milk samples.     

Brucellosis of camels in Kuwait

This study investigated the presence of Brucella antibodies in serum and milk obtained from camels in Kuwait. Brucella strains were also isolated from the foetus using standard technique (Webridge Lab Techniques). Three serological tests for serum were adopted. These tests were Rose Bengal Plate Test (RBPT), the Serum Tube Agglutination Test (SAT) and the Complement Fixation Test (CFT). The RBPT was used for all sera samples, and both SAT and CET were used for the positive RBPT. Camels that showed a titer of 1:40 in SAT or 1:5 in CFT or greater were considered positive. Thirteen of the samples examined were found positive by CFT (at 1:5); by SAT, they showed a titer of 1:20. One serological test, the Milk Ring Test (MRT), was used for milk. Here 3 and 2 were considered positive reactors but 1+ was considered suspicious. We were unable to isolate the Brucella organism from Sedemine and Cream of milk, but we isolated them from Foetus Brucella abortus and it is confirmed by Webridge Laboratory, U.K. It is Brucella abortus (Biovar 1). The prevalence rate was 14.8% from serum by the CFT and RBPT methods and 10.8% by the SAT method. For milk, the prevalence rate was 8.0%. Two Brucella abortus were isolated from 5 foetuses.     

Investigation of bovine brucellosis in the Northeastern Turkey

Bovine brucellosis, caused by Brucella abortus, is a significant problem for both public and animal health in Turkey. This study was conducted on the calving seasons between 2001 and 2006. A total of 626 serum samples of cattle obtained from 27 herds with a history of abortions was examined for Brucella antibodies by RBPT, SAT and ELISA. Of the cattle sera analysed, 221 (35,30%) and 206 (32, 92%) and 247 (39,45%) were found to be positive by RBPT , SAT and ELISA, respectively. B. abortus was isolated from 48 (32,21%) of 149 lung samples and stomach contents of the aborted fetuses. Based on the biochemical tests and the agglutination tests with monospecific A and M antisera, only 3 of the isolates were found to be B. abortus biotype 1 and the remaining 45 were biotype 3. This study also revealed that the dominant biotype of B. abortus was biotype 3 in this region. The determination of the agents responsible for bovine brucellosis and serosurvey of this disease are expected to help better understanding of this zoonotic infection in this region and neighbouring countries.     

补体结合酶联免疫吸附试验方法的建立

为改进免疫学诊断技术的准确性,研究了一种基于补体结合的免疫学检测新技术———补体结合酶联免疫吸附试验（CF-ELISA）。CF-ELISA技术采用酶标记抗菊糖纯化豚鼠补体C3抗体及其酶显色系统作为补体参与反应的指示系统,用ELISA方法进行补体结合试验。经对布氏菌病抗体检测的初步试验结果显示,CF-ELISA技术可检测到0.01 IU的布氏菌病抗体,灵敏度与间接酶联免疫吸附试验（iELISA）相当,是虎红平板凝集试验（RBPT）试管凝集试验（SAT）的5 000倍、补体结合试验（CFT）的10 000倍。对349份确诊布氏菌病感染群牛、羊血清的检测结果显示,CF-ELISAi、ELISA、CFT、SAT、RBPT的阳性率分别为35.82%3、6.39%、31.81%、30.09%、36.1%,CF-ELISA与iELISA、CFT、SAT、RBPT的阳性符合率分别为：98.4%、88.8%、80.0%、90.6%。CF-ELISAi、ELISA、CFT、SAT、RBPT对490份布氏菌病阴性群牛、羊血清的阴性率分别为100%、99.6%、100%、99.4%、99.8%,CF-ELISA与iELISA、CFT、SAT、RBPT的阴性符合率分别为：99.6%1、00%、99.4%、99.8%。研究表明,CF-ELISA是具有高特异性和高敏感性的布氏菌病免疫学检测技术。     

Comparison of four serological tests in the diagnosis of caprine brucellosis

Results from four serological tests for diagnosing brucellosis--serum tube agglutination (SAT), agar gel immunodiffusion (AGIT), Rose Bengal plate (RBPT) and complement fixation (CFT)--were compared using sera from goats from farms infected with Brucella melitensis. Ninety-two goats were negative and 29 positive to all four tests. The remaining 85 reacted to one or more tests. The RBPT was the most sensitive test and the AGIT the most specific, when compared with the CFT. The results suggest that the SAT adds little information when used with other tests but that RBPT and AGIT are useful for testing caprine brucellosis where facilities for the CFT are not available.     

Small ruminant brucellosis and community perception in Jijiga District,Somali Regional State,Eastern Ethiopia

A cross-sectional study of brucellosis in small ruminants was carried out from October 2008 to March 2009 in Jijiga District, Somali Regional State of Ethiopia. Seven hundred thirty sera samples (421 of sheep and 309 of goats) were randomly collected from purposively selected villages of the study area. Structured questionnaire format was developed, pre-tested and administered to assess the perception of the community pertaining to brucellosis in sheep and goats. Sera samples were screened by Rose Bengal Plate Test (RBPT), and all samples tested positive by the RBPT were subjected to Complement Fixation Test (CFT) for confirmation. Of 12 serum samples that were positive by RBPT, 11 were positive by CFT. Statistically significant differences were not observed between the species as well as the sex groups (P > 0.05); however, the variation between the age groups was statistically significant (P < 0.05). Analysis of the questionnaire survey suggests that improper handling of aborted materials, consumption of raw milk, and lack of awareness about the disease, among others, might greatly contribute to further spread of brucellosis in their livestock and exposes the community to a public health hazard. In general, the sero-prevalence in the study area was not so high; nevertheless, appropriate brucellosis control and prevention methods should be implemented to circumvent future potential for economic losses and the public health hazard of the disease.     

The use of skin delayed‐type hypersensitivity as an adjunct test to diagnose brucellosis in cattle: A review

Summary

Brucellosis, caused by bacteria of the genus Brucella, is a contagious disease that causes economic loss to owners of domestic animals due to loss of progeny and milk yield. Because cattle, sheep, goats, and to a lesser extent pigs are considered to be the source of human brucellosis, serological tests have been used to screen domestic animals for antibodies against Brucella. Although the serological tests helped to eradicate brucellosis in many countries, serological tests are not always adequate to detect latent carriers of Brucella. Therefore, the use of the skin delayed‐type hypersensitivity (SDTH) test, which is independent of circulating antibodies, might improve the diagnosis of brucellosis. In the literature, however, there are conflicting reports as to the value of the SDTH test for the diagnosis of brucellosis. Some studies consider the test unreliable, whereas others advocate its use because it detects brucellosis earlier than serological tests. The objectives of this study were therefore to assess the characteristics of the SDTH test, to select a Brucella strain that will yield a suitable brucellin for use in the field, and to determine whether the use of serological tests in combination with the SDTH test improves the detection of brucellosis. The results of this study clearly show that the SDTH test detects latent carriers of Brucella and confirms brucellosis in cattle with ambiguous serological test results. Brucellins prepared from smooth or mucoid strains of Brucella are better suited for use in the field than brucellins prepared from rough strains because they detect brucellosis in cattle with acute as well as chronic infection. The SDTH test is highly specific (99.3% specificity), and repeated testing of naive cattle or cattle infected with microorganisms that serologically cross‐react with Brucella does not sensitize cattle to subsequent SDTH tests. However, it is possible that some naive cattle may serologically react to the injection of brucellin. The effect of these serological reactions on the sero‐diagnosis of brucellosis is limited, because cattle may only now and then react serologically either with the serum agglutination test (SAT) or the complement fixation test (CFT). Nevertheless, cattle infected with microorganisms that serologically cross‐react with Brucella may test seropositive for brucellosis 4 to 7 weeks after injection of brucellin, depending on the cross‐reacting microorganism. The value of the SDTH test for the diagnosis of brucellosis was demonstrated after an outbreak of brucellosis. When the SDTH test was used in combination with SAT and CFT at diagnostic threshold ≥2 mm or ≥1 mm (increase in skinfold thickness), respectively, 39/44 (88%) or 42/44 (95%) of the infected cattle were detected compared with only 27/44 (61%) when SAT and CFT were used. When cattle in areas of low prevalence or in areas free from brucellosis are tested with the SDTH test an increase ≥2 mm in skinfold thickness should be considered indicative of infection. When the control and eradication of brucellosis is based on test‐and‐slaughter, an increase of ≥1 mm in skinfold thickness should be considered indicative of infection. Repeated serological testing complemented with the SDTH test in this programme will shorten the quarantine (movement control) period of a suspect herd, limiting the financial loss incurred during outbreaks of the disease. Consequently, since the SDTH test usually does not interfere with the serological diagnosis and can safely be used to establish the infection status of cattle in a suspect herd, it is opportune to consider adding the SDTH test to the procedure currently used to diagnose brucellosis in individual animals.     

A comparison of counter-immunoelectrophoresis with the rose bengal and the serum tube agglutination tests in the diagnosis of brucellosis in sheep

The counter-immunoelectrophoresis test (CIEPT) was compared with the rose bengal plate test (RBPT) and the serum agglutination test (SAT) in the diagnosis of brucellosis in 241 sheep. The total number of animals positive by one or more of the tests used was 106. Sixty animals were positive by all tests, while 87, 79 and 80 were positive by CIEPT, RBPT and SAT respectively. Based on the assumption that animals with an SAT titre of 40 I.U./ml or above were true positives, the CIEPT had a sensitivity of 82.5% and a specificity of 78.3% compared to 96.5% and 87% respectively, demonstrated by the RBPT. CIEPT might be used in flocks without clinical evidence of ram epididymitis if a test to supplement RBPT were required; but it would only partially replace SAT. Sera positive in RBPT but negative in CIEPT would have to be tested by SAT. With this combination, only about 22% of sera positive in RBPT would need to be further tested by SAT.     

虎红平板凝集试验与试管凝集试验检测奶牛布鲁菌病的比较

布鲁菌病主要采用凝集试验来检测,本试验用虎红平板凝集试验和试管凝集试验对江苏海安、江都、无锡和兴化地区的660头奶牛的血清样品进行平行检测,虎红平板凝集试验的阳性检出率为9.7%,试验管凝集试验的阳性检出率为5.5%;与后者相比,虎红平板凝集试验的敏感性为100%,特异性为95.3%,符合率为95.6%。这些数据表明,江苏地区某些奶牛场存在布鲁菌感染,虎红平板凝集试验可以用于布鲁菌病初步检测。     

Seroprevalence of camel brucellosis (Camelus dromedarius) in Somaliland

The present study was delineated to investigate the prevalence and risk factors of camel brucellosis in Northern Somalia (Somaliland). The study was carried out at three main districts of camel-rearing regions of Somaliland (Awdal, Waqoyi Galbed and Togdheer) in the period from July to November, 2008. A total of 1246 camel blood sera were randomly collected from 42 sporadic small scale camel herds. Two serological tests were used to screen all serum samples, Rose Bengal Plate Test (RBPT) and indirect ELISA (I-ELISA). Multivariate logistic regression was constructed to study the risk factors associated with Brucella seropositive cases. The overall prevalence of camel brucellosis in districts under investigation was 3.9% by RBPT and 3.1% by (I-ELISA). Multivariate logistic regression on animal level showed that locality (P < 0.05; OR: 6.254; CI, 1.186–32.976), herd size (P < 0.001; OR: 5.493; CI, 2.956-10–207), rearing with other ruminants (P < 0.001; OR: 12.433; CI, 3.957–39.060), and contact with other camels (P < 0.05; OR: 5.311; CI, 1.093–25.800) were the potential risk factors. However, herd size (P < 0.05; OR: 5.425; CI, 1.181–24.932), and rearing with other ruminants (P < 0.05; OR: 20.466; CI, 1.456–28.638) were recorded as risk factors on the herd level. The results of the present investigation indicate that the Brucella spp. exists within the camel herds in Somaliland. Further studies need to be done on Brucella infection in the other ruminants to determine which measure should be followed for control of brucellosis.     

Comparison of milk-ELISA and serum-ELISA for the diagnosis of Brucella melitensis infection in sheep

Milk and blood samples from 704 lactating ewes were examined for the diagnosis of Brucella melitensis infection by milk-ELISA, serum-ELISA, RBPT, SAT and culture of milk. Of these ewes, 209 were from brucellosis free sheep flock, 443 from brucellosis infected sheep flock and 52 were from private sheep flocks of which status for brucellosis was not known. All the 209 ewes belonging to uninfected sheep flock were found negative in all the tests and of the remaining 495 ewes 105 were positive in serum-ELISA, 103 in milk-ELISA, 92 in RBPT, 85 in SAT, and B. melitensis biovar-1 was isolated from the milk of 29 ewes. Of the 105 serum-ELISA positive ewes, 99 were positive and 6 were negative in milk-ELISA, whereas of the 103 milk-ELISA positive ewes, 4 were negative in serum-ELISA. All together, 99 ewes were positive and 386 were negative in both the assays while 10 ewes yielded variable results. The specificity of milk-ELISA in brucellosis free flock was 100% and sensitivity and positive predictive value were 96.11% and 94.28%, respectively, in infected flocks. The Brucella antibody levels in milk and serum samples as determined by milk-ELISA and serum-ELISA were correlated significantly. The milk-ELISA for brucellosis appears to be an attractive alternative of serum-ELISA particularly in the lactating ewes.     

A comparison of three serological tests in the diagnosis of caprine brucellosis.

The serum agglutination test (SAT), the Rose Bengal plate test (RBPT) and the milk ring test (MRT) were used in the diagnosis of caprine brucellosis. There was a close correlation between the SAT and RBPT when both tests were negative but the RBPT failed to detect 79.82 per cent of sera in excess of 50 iu. Also, owing to the relatively poor milking potential of the Nigerian goat and the false positive results with the MRT, it is concluded that the SAT offers a better serological diagnostic tool for caprine brucellosis in this locality.     

Serological response of cattle after vaccination and challenge with Brucella abortus

New and currently used serological procedures were evaluated using sera from cattle that were challenged with B. abortus S544 (S544) after vaccination with either B. abortus S19 (S19) or B. abortus 45/20 (S45/20) as calves or adults. In animals vaccinated with S19, titres to the indirect haemolysis test (IHLT) rose more slowly, declined more rapidly and involved fewer animals than did titres to the complement fixation test (CFT). In animals vaccinated with S45/20 the rough antigen complement fixation test (RCFT) showed persistent titres. At slaughter the IHLT and CFT were found to be more specific and more sensitive than the Rose Bengal Plate Test (RBPT) and Serum Agglutination Test (SAT) in the detection of cattle infected with B. abortus.     

Detection of <Emphasis Type="Italic">Brucella</Emphasis> sp. infection through serological,microbiological, and molecular methods applied to buffaloes in Maranhão State,Brazil

The aim of the current study is to diagnose Brucella spp. infection using methods such as serology, bacterial isolation, and molecular analysis in buffaloes bred in Maranhão State. In order to do so, 390 samples of buffalo serum were subjected to serological tests, to Rose Bengal Plate Test (RBPT) and to 2-mercaptoethanol (2-ME) combined with slow agglutination test (SAT). Vaginal swabs were collected from seropositive animals and subjected to bacterial isolation and to generic PCR. According to the serological test, 16 animals had a positive reaction to the confirmatory test (2-ME/SAT). As for bacterial isolation, three samples resulted in the isolation of Brucella spp.-characteristic colonies, which were confirmed through PCR. These results confirmed Brucella spp. infection in the buffalo herd from Maranhão State.     

Sero-prevalence of bovine brucellosis and its risk factors in Jimma zone of Oromia Region,South-western Ethiopia

A cross sectional sero-prevalence study was conducted on 1,595 cattle in Jimma zone, Ethiopia to investigate the status of bovine brucellosis and identify potential risk factors. Sera samples were analyzed using Rose Bengal Plate Test (RBPT) and Complement Fixation Test (CFT). The overall individual and herd level sero-prevalences were 3.1% (n = 1,595) and 15.0% (n = 227), respectively. The sero-prevalence of bovine brucellosis at individual animal level was significantly higher in non-pregnant (11.18%) than pregnant (2.77%) and lactating (22.35%) than non-lactating animals (2.46%). Moreover, significantly higher sero-prevalence was observed in herds of larger sizes. Individual animal sero-prevalence was also positively associated with the occurrence of abortion (26.98 and 1.54% in those with and without previous history of abortion, respectively). Generally, the sero-prevalence of bovine brucellosis found in Jimma area was not high and the sero-prevalence was closely associated with some of the risk factors considered at individual animal and herd level.     

Survey of brucellosis in goats and sheep in the yemen arab republic: Comparison of tests forBrucella melitensis infection in sheep

Summary Sera from 538 Yemeni goats and 690 Yemeni sheep were screened for brucellosis by the Rose Bengal Plate Test (RBPT) and reactors confirmed by the complement fixation test (CFT) and the serum agglutination test (SAT). The prevalence among goats was 0·4% and among sheep 0·6%. The prevalence among 183 imported goats and sheep was 4·4%. The sensitivity and specificity of three seřological tests available for the diagnosis of brucellosis—CFT, RBPT and SAT—were compared using ovine sera obtained throughout an outbreak of abortion due toBrucella melitensis. The RBPT and the SAT were relatively insensitive compared with the CFT (71 and 44% respectively) and the RBPT was as specific as the SAT when suspicious sera were included. The results suggests that the SAT adds little information when used with other tests and the RBPT has limited applications as a screening test for ovine brucellosis.

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Resumen Se examinaron 538 sueros de cabras Yemeni y 690 de ovejas Yemeni, para detectar brucelosis, mediante la prueba Rose de Bengala (RB) confirmando los reactores con la prueba de fijación del complemento (FC) y de seroaglutinación (SA). La prevalencia en cabras fue de 0.4% y en ovejas de 0.6%. La prevalencia dentro de 183 cabras y ovejas importadas fue de 4.4%. La sensibilidad y especificidad de las tres pruebas serológicas utilizadas, se comparó usando suero ovino obtenido en un brote confirmado de brucelosis porBrucella melitensis. Las pruebas de (RB) y (SA) fueron relativamente insensibles comparadas con la de (FC) (71% y 44% respectivamente), y la de (RB) fue tan específica como la de (SA). Los resultados sugieren que, la prueba de (SA) a?ade poca información cuando se utiliza con otras pruebas, y que la de (RB) tiene aplicación limitada para un diagnóstico de población para brucelosis ovina.

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Résumé Des sérums provenant de 538 chèvres et 690 moutons du Yemen on été analysés pour le dépistage de la brucellose par le test des lames au Rose Bengale (TLRB) et les réactions positives ont été confirmées par le test de la fixation du complément (FC) et le test d'agglutination du sérum (TAS). Le taux de fréquence chez les chèvres était de 0,4 p. 100 et chez les moutons de 0,6 p. 100 Le taux de chez 183 ovins et caprins importés étai de 4,4 p. 100 La sensibilité et la spécificité des trois tests sérologiques utilisés dans le diagnostic de la brucellose—TLRB, FC et TAS—ont été comparés sur des sérums ovins obtenus tout au long d'une épidémie d'avortements dus àBrucella melitensis. Le test au Rose Bengale et le test d'agglutination du sérum se sont montrés relativement peu sensibles comparés à la fixation du complément (7 et 44 p. 100 respectivement) et la spécificité du test au Rose Bengale était égale à celle du test de l'agglutination du sérum lorsque des sérums douteux étaient inclus. D'après les résultats, le TAS, utilisé conjointement avec les autres tests apporte peu d'informations supplémentaires et le TLRB a des applications limitées en tant que test de dépistage de la brucellose ovine.

     

Seroprevalence of <Emphasis Type="Italic">Brucella</Emphasis> antibodies in camels in Katsina State,Nigeria

A cross-sectional study was carried out to determine the status of Brucella infection in one-humped (Dromedary) camels in the North and Central senatorial districts of Katsina State, Nigeria. Nine hundred and eighty serum samples from live and slaughtered camels were tested. Modified Rose Bengal plate test (RBPT) and serum agglutination test (SAT) with ethylenediaminetetraacetic acid, (EDTA) were used as screening and standard tests, respectively. The prevalence of Brucella antibodies were 110 (11.2%) and 103 (10.5%) for RBPT and SAT, respectively. Of the 472 and 508 serum samples tested from the herds and abattoirs, respectively, 63 (13.3%) and 47 (9.3%) were positive by RBPT while 62 (13.1%) and 41 (8.1%) were positive by SAT, respectively. Based on the results, it was concluded that Brucella antibodies were present in camels in the study area. Poor management practices and mixing of camels with other species of livestock as well as unrestricted movement of camels were proposed to be the reasons for the prevalence of the disease in the study area. In view of the public health importance of the disease, it is recommended that there is the need to develop a strategic plan to decrease spread of brucellosis in the study area.     

Brucella melitensis infection in dog: a critical issue in the control of brucellosis in ruminant farms

Canine brucellosis is a contagious disease associated with health implications for humans as well as for a wide range of wild and domesticated animals. In this study, 173 dog blood specimens were sampled from herding dogs in three different provinces including Tehran (n = 127), Qom (n = 40) and Alborz (n = 6) provinces. The presence of Brucella antibodies was determined using Rose Bengal plate test (RBPT), slow agglutination test (SAT) and 2-mercaptoethanol (2-ME), respectively. The seropositive samples were further screened using blood culture and PCR tests to identify and differentiate the implicated Brucella species. According to our results, 24.3% (42/173), 13.8% (24/173) and 6.3% (11/173) of blood samples were tested positive using RBPT, SAT and 2-ME, respectively. However, among 42 seropositive samples, only 38.1% (16/42) and 14.2% (6/42) were positive by PCR and culture, respectively. Brucella melitensis biovar 1 and biovar 2 was isolated from the bacterial cultures of 6 blood samples and confirmed by biotyping, AMOS PCR and Bruce-ladder PCR assays. These findings highlight the potential risk of Brucella transmission from dog to humans along with other livestock and reflect the critical role of infected dogs in the persistence of Brucella infections among ruminant farms. This study stresses the need for further epidemiological investigations on canine brucellosis among herding dogs and suggests the systematic screening of the disease among companion animals such as dogs in order to improve brucellosis surveillance and control programs.     

The use of skin delayed-type hypersensitivity as an adjunct test to diagnose brucellosis in cattle: a review

Brucellosis, caused by bacteria of the genus Brucella, is a contagious disease that causes economic loss to owners of domestic animals due to loss of progeny and milk yield. Because cattle, sheep, goats, and to a lesser extent pigs are considered to be the source of human brucellosis, serological tests have been used to screen domestic animals for antibodies against Brucella. Although the serological tests helped to eradicate brucellosis in many countries, serological tests are not always adequate to detect latent carriers of Brucella. Therefore, the use of the skin delayed-type hypersensitivity (SDTH) test, which is independent of circulating antibodies, might improve the diagnosis of brucellosis. In the literature, however, there are conflicting reports as to the value of the SDTH test for the diagnosis of brucellosis. Some studies consider the test unreliable, whereas others advocate its use because it detects brucellosis earlier than serological tests. The objectives of this study were therefore to assess the characteristics of the SDTH test, to select a Brucella strain that will yield a suitable brucellin for use in the field, and to determine whether the use of serological tests in combination with the SDTH test improves the detection of brucellosis. The results of this study clearly show that the SDTH test detects latent carriers of Brucella and confirms brucellosis in cattle with ambiguous serological test results. Brucellins prepared from smooth or mucoid strains of Brucella are better suited for use in the field than brucellins prepared from rough strains because they detect brucellosis in cattle with acute as well as chronic infection. The SDTH test is highly specific (99.3% specificity), and repeated testing of naive cattle or cattle infected with microorganisms that serologically cross-react with Brucella does not sensitize cattle to subsequent SDTH tests. However, it is possible that some naive cattle may serologically react to the injection of brucellin. The effect of these serological reactions on the sero-diagnosis of brucellosis is limited, because cattle may only now and then react serologically either with the serum agglutination test (SAT) or the complement fixation test (CFT). Nevertheless, cattle infected with microorganisms that serologically cross-react with Brucella may test seropositive for brucellosis 4 to 7 weeks after injection of brucellin, depending on the cross-reacting microorganism. The value of the SDTH test for the diagnosis of brucellosis was demonstrated after an outbreak of brucellosis. When the SDTH test was used in combination with SAT and CFT at diagnostic threshold > or =2 mm or > or =1 mm (increase in skinfold thickness), respectively, 39/44 (88%) or 42/44 (95%) of the infected cattle were detected compared with only 27/44 (61%) when SAT and CFT were used. When cattle in areas of low prevalence or in areas free from brucellosis are tested with the SDTH test an increase > or =2 mm in skinfold thickness should be considered indicative of infection. When the control and eradication of brucellosis is based on test-and-slaughter, an increase of > or =1 mm in skinfold thickness should be considered indicative of infection. Repeated serological testing complemented with the SDTH test in this programme will shorten the quarantine (movement control) period of a suspect herd, limiting the financial loss incurred during outbreaks of the disease. Consequently, since the SDTH test usually does not interfere with the serological diagnosis and can safely be used to establish the infection status of cattle in a suspect herd, it is opportune to consider adding the SDTH test to the procedure currently used to diagnose brucellosis in individual animals.     

Experience with simple ELISA test systems for Brucella serology in cattle, sheep and goats

The objective of this work was to use the ELISA technique for the serological surveillance for freedom of brucellosis of cattle, sheep and goats. By comparing 28 cattle sera taken after a brucellosis outbreak, 15 bovine sera supplied by the Federal Institute for Health Protection of Consumers and Veterinary Medicine (BgVV) and 497 serum slow agglutination test (SSAT) and complement fixation test (CFT) negative bovine sera from herds officially declared free of brucellosis, the ELISA technique not only shows higher sensitivity as compared to SSAT and CFT but also distinguishes clearly between positive and negative reactions. The serological comparison by SSAT, CFT and ELISA of 615 cattle, 624 sheep and 630 goat sera from herds acknowledged as brucellosis free showed equivalent specificities for both CFT and ELISA. The specificity of the SSAT was much lower, 81.1% in cattle and 96.2% in goat sera. The examination of 5796 cattle, 1337 calf, 5031 sheep and 1796 goat sera demonstrates the advantage of the ELISA technique as routine method. The possible application of the ELISA technique as a screening method for serological brucellosis tests in sheep, goats and possibly also in pigs is discussed.