Comparative efficacy of standard AGID and precipitinogen inhibition test with monoclonal antibodies based competitive ELISA for the serology of <Emphasis Type="Italic">Peste des Petits Ruminants</Emphasis> in sheep and goats

This project was conducted to investigate the comparative efficiency of competitive ELISA (cELISA), standard Agar Gel Immunodiffusion Test (AGID) and Precipitinogen Inhibition Test (PIT) for the diagnosis of Peste des Petits Ruminants (PPR) in Pakistan. To deal with this, serum samples from 198 sheep and 82 goats were collected from three different government livestock farms and all the samples were run simultaneously with the three serological tests. The samples found positive for PPR antibodies through cELISA, AGID and PIT were 96 (34.2%), 60 (21.4%) and 72 (25.7%), respectively. Kappa statistics were applied to evaluate the concordance between the laboratory-based test (cELISA) and field-based tests (AGID and PIT). Kappa statistics scores for cELISA versus AGID and PIT were 0.6343 (95% Confidence Interval CI 0.5231–0.7456) and 0.7134 (95% Confidence Interval CI 0.5987–0.8281), respectively, which indicate a “substantial” agreement between cELISA and AGID and “significant” agreement between cELISA and PIT. AGID and PIT revealed relative diagnostic sensitivities with cELISA of 59.3% and 69.7% and relative diagnostic specificities of 98.3% and 97.2%, respectively. The data suggested that for mass screening and control of PPR, these serological tests proved practical in the absence of cELISA since they have high relative diagnostic specificities and a satisfactory relative diagnostic sensitivities.     

Peste des petits ruminants infection in domestic ruminants in Sudan

The existence of peste des petits ruminants (PPR) in domestic ruminants and camels in Sudan during 2008–2012 was investigated. Lung tissues and serum samples were randomly collected from sheep, goats, cattle, and camels at different areas of Sudan. A total of 12,384 serum samples were collected from clinically healthy 7413 sheep, 1988 camels, 1501 cattle, 1459 goats, and 23 gazelles at different areas in the Sudan. They were examined for PPR antibodies using competitive ELISA (cELISA). The overall detected seroprevalence of PPR in tested sera was 49.4%; seroprevalence values within species were 67.1, 48.2, 25.8, 2.1, and 21.7% in sheep, goat, cattle, camels, and gazelles, respectively. The highest seroprevalence (68.1%) was observed in sera collected from Darfur states, then the central states (54.3%). A total of 1276 lung tissue samples (623 sheep, 324 cattle, 220 camels, and 109 goats) were collected. The majority of lung samples were collected from clinically healthy animals that showed lesions on PM in slaughterhouses (95%) and during PPR outbreaks; samples were tested for PPR antigen using immunocapture ELISA (IcELISA). PPR antigen was detected in 233 out of the 1276 tested samples (18.3%). Positive results were observed in samples collected from clinically healthy and diseased animals. The observed prevalence values in each species were 33.6, 21.1, 15.4, and 12.3% in camel, goat, sheep, and cattle, respectively. PPR antigen was detected in samples from different areas; however, the highest prevalence (63.9%) was found in samples collected from the eastern states, then Khartoum state (28%). Trials for virus isolation were done in different cell cultures. Out of 30 IcELISA-positive samples inoculated in primary bovine and ovine kidney cells, Vero cells, the PPR virus was successfully isolated from 15 (eight sheep, five camels, and two goats) samples in the three cell culture types. Using RT-PCR, PPRV nucleic acid was detected in all 25 IcELISA-positive tested samples.     

A competitive ELISA for detection of antibodies to the group antigen of bluetongue virus.

A competitive enzyme-linked immunosorbent assay (cELISA) was developed to detect antibodies to the group antigen of bluetongue virus (BTV). The epitope recognized by the BTV-specific monoclonal antibody was confirmed, by immunofluorescence staining of monolayers of virus-infected Vero cells, to be present on BTV serotypes 2, 10, 11, 13, and 17 but not on epizootic hemorrhagic disease virus (EHDV) serotypes 1 and 2. Sera from BTV-inoculated ruminants and rabbits were used to evaluate the cELISA and to compare its specificity and sensitivity with that of the conventional BTV-specific agar gel immunodiffusion (AGID) and serum neutralization (SN) tests. Rabbit antisera to the 5 serotypes of BTV present in the United States had cELISA titers (inverse of the final dilution of serum that gave greater than 20% inhibition) that ranged from 32 to greater than 1.024. Seroconversion of the 8 calves and lambs inoculated with BTV was detected by all 3 serologic tests (SN, AGID, cELISA) by 6 weeks after inoculation. Specificity of the cELISA test was confirmed with bovine sera that contained neutralizing antibodies to EHDV but not to the 5 serotypes of BTV present in the United States; these sera gave positive results by AGID test but were negative by cELISA. The sensitivity and specificity of the cELISA test was further confirmed by analysis of a panel of bovine test sera supplied by the National Veterinary Services Laboratories, indicating that the cELISA is a superior test for detection of BTV group-specific antibodies in sera from ruminants in the United States.     

内蒙古地区健康及患阴道蝇蛆病双峰驼的主要血液指标比较分析

旨在了解内蒙古地区健康及患阴道蝇蛆病双峰驼的主要血液指标之间的差异。从内蒙古阿拉善左旗等地采集健康及患阴道蝇蛆病双峰驼血液样本107份,采用瑞氏染色法和吉姆萨染色法对制备的血液涂片进行染色,观察并比较健康及患病双峰驼血液的红细胞与白细胞的形态特征;利用血液细胞分析仪测定血液样本的血细胞含量,并对相同及不同地区的健康及患病双峰驼的主要血常规指标进行统计学分析;应用比值方法估计血液样本的血浆含量。结果表明,患病驼血液中的嗜碱性粒细胞含量较少,嗜酸性粒细胞含量较多,且血小板含量较健康驼多;来自相同地区的患病驼与健康驼的各种血细胞含量无显著差异（P〉0.05）;不同地区的健康驼血细胞含量趋于平稳,但不同地区的患病驼血细胞含量变化存在较大波动;双峰驼的血浆含量为0.349 0-0.736 5,患阴道蝇蛆病的双峰驼血浆含量普遍高于健康双峰驼。     

Comparison of competitive ELISA, indirect ELISA and standard AGID tests for detecting blue-tongue virus antibodies in cattle and sheep

The performances of a competitive enzyme-linked immunosorbent assay (ELISA) using a group specific monoclonal antibody against bluetongue virus, an indirect ELISA and the standard agar gel immunodiffusion (AGID) test were compared in the detection of serum antibody against bluetongue virus. Test sera consisted of 1300 bovine, 530 ovine and 160 carpine samples from bluetongue-free areas of Canada, 605 bovine and ovine field samples from the USA and Barbados and 464 samples from 79 cattle and sheep experimentally infected with 19 South African and five USA serotypes of bluetongue virus. The diagnostic specificity of the competitive ELISA, as determined for the bluetongue virus-free cattle sera was superior (99.92 per cent) to that of the indirect ELISA (99.85 per cent) and the AGID (99.0 per cent). The specificities of the competitive ELISA for sheep (99.63 per cent) and goats (100.0 per cent) sera were also higher than those of the AGID test. The performance of the ELISA tests was similar whether a gamma-ray-irradiated (2.0 Mrad) or a non-irradiated bluetongue virus antigen preparation was used. The competitive ELISA results for bovine field sera from endemic areas demonstrated a relatively low level of agreement (92.04 per cent) with AGID test results, with 9.7 per cent false negatives. The possible presence in these sera of antibody to cross-reacting antigens or to other orbiviruses, eg, epizootic haemorrhagic disease virus, which react in the AGID but not in the competitive ELISA may account for this lack of agreement.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of antibody-ELISA and real-time RT-PCR for the diagnosis and profiling of bluetongue virus serotype 8 during the epidemic in Belgium in 2006

In 2006 bluetongue (BT) emerged for the first time in North-Western Europe. Reliable diagnostic tools are essential in controlling BT but data on the diagnostic sensitivity (Se) and specificity (Sp) are often missing. This paper aims to describe and analyse the results obtained with the diagnostics used in Belgium during the 2006 BT crisis. The diagnosis was based on a combination of antibody detection (competitive ELISA, cELISA) and viral RNA detection by real-time RT-PCR (RT-qPCR). The performance of the cELISA as a diagnostic tool was assessed on field results obtained during the epidemic and previous surveillance campaigns. As the infectious status of the animals is unknown during an epidemic, a Bayesian analysis was performed. Both assays were found to be equally specific (RT-qPCR: 98.5%; cELISA: 98.2%) while the diagnostic sensitivity of the RT-qPCR (99.5%) was superior to that of the cELISA (87.8%). The assumption of RT-qPCR as standard of comparison during the bluetongue virus (BTV) epidemic proved valid based on the results of the Bayesian analysis. A ROC analysis of the cELISA, using RT-qPCR as standard of comparison, showed that the cut-off point with the highest accuracy occurred at a percentage negativity of 66, which is markedly higher than the cut-off proposed by the manufacturer. The analysis of the results was further extended to serological and molecular profiling and the possible use of profiling as a rapid epidemiological marker of the BTV in-field situation was assessed. A comparison of the serological profiles obtained before, during and at the end of the Belgian epidemic clearly showed the existence of an intermediate zone which appears soon after BTV (re)enters the population. The appearance or disappearance of this intermediate zone is correlated with virus circulation and provides valuable information, which would be entirely overlooked if only positive and negative results were considered.     

Molecular and serological prevalence of Anaplasma marginale in cattle of North Central Morocco

A cross sectional study was conducted to investigate the epidemiological distribution of Anaplasma marginale in North Central Morocco. Blood samples from five provinces of Morocco were collected from apparently healthy cattle (n=668) and simultaneously analyzed by a nested polymerase chain reaction (nPCR) assay and competitive enzyme-linked immunosorbent assay (cELISA). The overall prevalence of A. marginale was 21.9% by nPCR and 16.5% by cELISA. The Kappa coefficient between nPCR and cELISA indicated a modest level of agreement (0.54). The prevalence of A. marginale varied significantly according to the province and the month of sampling. However age, gender and breed did not have a significant effect on the prevalence of this pathogen. The highest prevalence of A. marginale was found in the Gharb, a sub-humid area while the lowest was reported in the Saiss, a semi-arid area. These results indicate that an A. marginale infection are widespread in the country and suggests that either or both techniques are excellent tools for epidemiological studies and control programs.     

Prevalence of antibodies to bluetongue virus and Anaplasma marginale in Montana yearling cattle entering Alberta feedlots: Fall 2001

A serologic survey was conducted in yearling cattle imported into Alberta feedlots from Montana during October 2001 to estimate the prevalence of antibodies to bluetongue virus (BTV) and Anaplasma marginale in Montana yearling cattle. The apparent prevalence of antibodies to BTV when the competitive enzyme-linked immunosorbent assay (cELISA) was used was 0.37% (21/5608). Test positive cELISA samples were also all positive when tested by virus neutralization (VN) and they reacted to 1 or more BTV serotypes, including 2, 10, 11, 13, and 17. The apparent prevalence of antibodies to A. marginale when a recombinant cELISA (rcELISA) was used with a positive cutoff at 30% inhibition was 1.93% (108/5608). When the rcELISA positive cutoff was at 42% inhibition, the apparent prevalence was 0.73% (41/5608). After the reported sensitivity and specificity of the test had been accounted for, the A. marginale antibody results were consistent with a population that was either free of exposure or had a very low prevalence for A. marginale.     

Vitamin C concentrations in blood plasma,tissues and urine of camels (Camelus dromedarius) in Sudanese herds

There is suggestive evidence that a low status of ascorbic acid in ruminants is related with decreased disease resistance. In a first attempt to identify conditions in camels that could affect their health, an inventory was made of ascorbic acid (vitamin C) concentrations in plasma and tissues as related to breed, gender, sexual activity and season. A total of 3429 camels were studied and sub-samples were used for selected comparisons. The highest concentrations of ascorbic acid were found in adrenals (152 mg/100 g wet tissue) and the lowest in heart (8 mg/100 g), the levels being unrelated with season. Arabi camels had higher plasma concentrations of ascorbic acid (6.42 microg/ml) than did Anafi and Bishari camels, the latter breed showing the lowest concentrations (3.24 microg/ml). Female camels of the Anafi breed had higher concentrations urinary ascorbic acid than did their male counterparts. It is suggested that in camels the main elimination route of vitamin C is with urine. Female and male Arabi camels that were sexually active had 52 and 23% lower plasma ascorbic acid concentrations than did their sexually inactive counterparts. It is suggested that especially Bishari camels during the breeding season might be sensitive to disease.     

A survey of camel (Camelus dromedarius) diseases in Jordan.

Information on incidences of camel (Camelus dromedarius) diseases in Jordan is scarce. In this survey, 369 live and 156 slaughtered camels were examined in four Jordanian geographic regions and the proportion of diseased camels was calculated. Intestinal parasite ova were detected in 98% of camels; one or more species of external parasites were found on the skin of all camels; 33% had nasal myiasis; and hydatid cysts were identified in 44% of the slaughtered animals. Sarcoptic mange (Sarcoptes scabiei var. cameli) and trypanasomiasis, two diseases of economic importance, were also diagnosed in 83% and 33% of the 32 and 257 examined camels, respectively. Rabies virus was detected in eight camels by use of fluorescent antibody examination of brain tissues. Foreign-body accumulation within the first and second stomach compartments was the predominant gastrointestinal disease of slaughtered adult camels (22%). Ten percent of slaughtered camels had bacterial pneumonia, with Pasteurella hemolytica most often isolated (56% of pneumonic lungs). Further investigation into the relationship between parasite burden and health in camels is required to assess the significance of the high prevalence of parasites.     

A seroepidemiological study on bluetongue virus in dairy cattle in the central valley of California

A seroepidemiological study on bluetongue virus (BTV) infection in California dairy cattle was conducted to estimate the prevalence and distribution by age and season of BTV group-reactive antibodies and to look for possible associations between the presence of antibodies and cattle age or breed and farm. Between December 1985 and March 1987, a sample of cattle was tested at approximately two-month intervals for BTV group-reactive antibodies using an enzyme-linked immunosorbent assay (ELISA). Data taken during the month of December 1986 were used to evaluate possible associations between a positive antibody test and certain intrinsic (age, breed) and extrinsic (farm) factors.Univariate and multivariate statistical analyses using the -square test for associations and multiple logistic regression, respectively, were carried out for possible associations between positive antibody tests to BTV and each factor of interest. The strengths of the associations were determined using estimates of the odds ratio.Of the 3774 serum samples tested, 238 (6.3%) were from calves, 1045 (27.6%) were from heifers and 2492 (66.0%) were from cows. Seroprevalence varied from nil in calves on two occasions to over 90% on several occasions in cows. Cows consistently had higher prevalence rates than heifers or calves across all test dates (p<0.05). The seroprevalence of BTV group-reactive antibodies also showed a seasonal fluctuation, with the highest rates occurring during the warmer months of the year. These highest prevalence rates coincided with heavy activity of the known vector of BTV, Culicoides spp. Breed and farm effects were not statistically significant (p>0.05). With the exception of one farm, all cattle were of the Holstein breed, which reduced confidence in assessing any breed effect in this study. Relative estimates of the sensitivity and specificity of BTV ELISA were 87% and 100% respectively, compared to the standard agar gel immunodiffusion (AGID) test.The observations support previous findings of seasonal distribution of BTV antibodies and suggest an age relationship, whereby older cattle are more likely to be positive to BTV group-reactive antibodies than younger cattle.     

Serum protein electrophoretic pattern in young and adult camels

OBJECTIVE: To compare the electrophoretic pattern of serum proteins in clinically healthy adult camels (between 3 and 8 years of age) and camel calves (less than 3 months of age). DESIGN: Laboratory analysis of serum from healthy camels. PROCEDURE: Blood was collected from 30 healthy adult camels and 30 camel calves and the serum separated. Total protein of each serum sample was estimated by automated chemistry analyser. The proteins were fractionated by automated electrophoresis on agarose gel. RESULTS: Serum proteins migrated on the agarose gel as one albumin, two alpha (alpha1 and alpha2-globulins), two beta (beta1 and beta2-globulins) and one gamma-globulin fractions. In adult camels the mean concentration of total protein, albumin alpha1, alpha2, beta1, beta2 and gamma-globulins was 56.8 +/- 1.5, 30.7 +/- 0.8, 2.4 +/- 0.1, 3.2 +/- 0.1, 9.7 +/- 0.3, 3.4 +/- 0.2 and 8.6 +/- 0.3 g/L, respectively. These values in calves were 49.7 +/- 1.8, 23.7 +/- 0.8, 3.2 +/- 0.2, 3.1 +/- 0.2, 14.2 +/- 0.2, 4.0 +/- 0.2 and 4.1 +/- 0.2 g/L, respectively. CONCLUSION: The concentration of total proteins, albumin and gamma-globulins was higher (P < 0.05) in the adult camels than in camel calves. The concentrations of beta1 globulins was higher (P < 0.05) in calves as compared to adult camels.     

Temporal development of bluetongue virus protein-specific antibody in sheep following natural infection

Humoral immune responses of sheep to natural bluetongue virus (BTV) infection were studied on a temporal basis. The temporal development of viral protein-specific IgG was determined by western immunoblotting; virus neutralization and agar gel immunodiffusion (AGID) were conducted for comparative purposes. Prior to the emergence of the arthropod vector and the associated transmission of BTV, virus-neutralizing antibody was absent from all sentinel sheep; 3 sheep had pre-existing AGID antibody and all sheep had IgG, specific for 4 viral proteins, as determined by immunoblotting. Following emergence of the BTV vector, 9 of 11 sheep became infected, as determined by virus isolation, with BTV. All sheep developed virus-neutralizing and AGID antibody. However, only those sheep with a demonstrable viremia experienced an increase in viral protein-specific antibody. Development of viral protein-specific IgG varied with the individual animal and no obvious correlation between a specific response and protective immunity or viral clearance was noted. From a diagnostic viewpoint, the immunoblotting procedure was superior in identifying past exposure to BTV, as compared with neutralization and AGID. In addition, the application of immunoblotting to paired serum samples appeared to be a sensitive indicator of viremia.     

Factors influencing the prevalence of subclinical mastitis in lactating dromedary camels in Riyadh Region,Saudi Arabia

The purpose of this study was to determine the prevalence of subclinical mastitis in camels in Riyadh, Saudi Arabia and the factors influencing its incidence. A total of 740 quarter milk samples were collected from 47 camel herds belonging to Majahim, Maghatir, Shu’l, and Sufer breeds. California mastitis test (CMT) was used as a screening test for subclinical mastitis. Samples giving negative or trace CMT scores (0) were assigned to healthy quarters, while those giving positive scores of 1+ to 3+ were assigned to subclinically affected quarters. Logistic regression was used to assess the association of breed, parity, and stage of lactation with the prevalence of subclinical mastitis. Milk fat, protein, lactose, solid nonfat percentages and Na, Ca, and K concentrations were compared in CMT-positive versus healthy quarters. One third (33%) of tested quarters had subclinical mastitis based on CMT. The estimated probability of subclinical mastitis with the combined effects of breed, parity, and stage of lactation ranged from 15.8% to 54.6%. The risk of subclinical mastitis increased significantly with parity and with the early stage of lactation. The Shu’l breed had significantly higher prevalence of subclinical mastitis than other breeds. Significant decreases in protein, lactose, and solid nonfat, Ca and K concentrations and increase in Na concentrations were associated with subclinical mastitis. In conclusion, subclinical mastitis is prevalent in Saudi camels, and its incidence is influenced by breed, parity, and stage of lactation.     

蓝舌病灭活疫苗免疫羊ELISA和琼扩监测比较试验

用19只绵羊（注苗前BTV琼扩和ELISA均为阴性）注射BTV灭活苗后7～139天的血清进行BTVELISA和琼扩平行试验，结果表明，注苗后7～30天11只试验丰ELISA阳性，注苗40天13只羊ELISA阳性，注苗90天以后全部试验羊只均为ELISA阳性，而琼扩试验则始终为阴性结果。     

First outbreak of bluetongue in goats in The Netherlands

For the first time, bluetongue has been diagnosed in goats in the Netherlands and in Northwest-Europe. On the 17th of August 2006, bluetongue was for the first time diagnosed in sheep and a little later in cattle in The Netherlands. The clinical symptoms, diagnostics and differential diagnosis of bluetongue (BT) in goats in the Netherlands are described. The most obvious clinical signs were an acute drop in milk production and high fever (up to 42 degrees C). Clinical signs were less obvious than usually seen for clinically diseased sheep and cattle. A few goats showed oedema of the lips and the head, some nasal discharge and scabs on the nose and lips. Further erythema of the skin of the udder and small subcutaneous hemorrhages were seen. Just like one year ago, for the very first suspicion of bluetongue in Northwest-Europe, a good collaboration between practitioners, specialists of the Animal Health Service (GD Deventer), the Specialist Team of the Food and Consumer Product Safety Authority (VWA), and the Central Institute for animal Disease Control (CIDC-Lelystad) in The Netherlands, led to the first and rapid notification and confirmation of the suspicion of bluetongue.     

Comparison of agar gel immunodiffusion test, rapid slide agglutination test, microbiological culture and PCR for the diagnosis of canine brucellosis

The performance of the rapid slide agglutination test, with and without 2-mercaptoethanol (RSAT and 2ME-RSAT) and agar gel immunodiffusion test (AGID) was evaluated for the diagnosis of brucellosis in naturally infected dogs. The microbiological culture, PCR and clinical parameters were used as reference. A total of 167 dogs were clinically examined and tested by blood culture, culture of semen/vaginal swab and PCR in blood and semen/vaginal swab. According to the results observed the 167 dogs were divided into three groups: Brucella canis infected dogs (Group 1), B. canis non-infected dogs (Group 2) and dogs with suspected brucellosis (Group 3). The dogs were then tested by RSAT, 2ME-RSAT and AGID. Groups 1 and 2 were used to calculate the diagnostic sensitivity and specificity of the serological tests and the results observed in Group 3 were also discussed. The diagnostic sensitivity of RSAT, 2ME-RSAT and AGID was respectively 70.58%, 31.76%, and 52.94%. The diagnostic specificity of RSAT, 2ME-RSAT and AGID was respectively 83.34%, 100%, and 100%. In dogs with suspected brucellosis 15% were RSAT positive, none was 2ME-RSAT positive and 5% were AGID positive. Although the serological tests are the most commonly used methods for brucellosis diagnosis, a significant proportion of false-negative results were observed highlighting the importance of the direct methods of diagnosis, like blood culture and PCR to improve the diagnosis of canine brucellosis.     

Early detection of maedi-visna (ovine progressive pneumonia) virus seroconversion in field sheep samples.

The aim of this work was to investigate whether an enzyme-linked immunosorbent assay (ELISA) was useful for early detection of maedi-visna virus (MVV) infection in sheep under field conditions. An ELISA based on p25 recombinant protein and a gp46 synthetic peptide was used. Sequentially obtained serum samples (n = 1,941) were studied for 4 years. ELISA results were compared with those of the agar gel immunodiffusion (AGID) test, and results of both tests were compared with a reference result established using consensus scores for at least 2 of 3 serologic techniques (AGID, ELISA, and western blotting, which was used to resolve result discrepancies between the other 2 techniques). A total of 247 discrepancies were observed between ELISA and AGID. Of these, 131 were due to an earlier detection of 120 sera by the ELISA and 11 sera by AGID. The remaining discrepancies (116) were due to the presence of false reactions in both tests. Fewer false-negative results were found by ELISA than with AGID (6 vs. 69 sera, respectively), whereas the number of false-positive results was virtually the same for ELISA and AGID (21 vs. 20, respectively). In relation to the reference result, ELISA sensitivity and specificity were 97.8% and 98.2%, respectively, whereas values for AGID were 76.3% and 98.3%, respectively. The agreement between ELISA and the reference result was higher than that between AGID and the reference result (K value: 0.96 and 0.77, respectively). A variation in the ELISA signal (based on optical density) was observed during the study period, suggesting different antibody levels throughout the animal's life. The ELISA was useful for detecting MVV-infected sheep in field conditions and has potential for use in control and eradication programs.     

Performance evaluation of a competitive ELISA test used for bluetongue antibody detection in France, a recently infected area

In 1998, bluetongue (BT) was introduced in northern Africa and then extended to northern latitudes including the French island of Corsica. Following the outbreaks in Corsica in 2000 and 2001, cross-sectional studies and surveillances have been set up in Corsica and also in the southern part of mainland France, a disease-free area but considered at high risk because of its proximity. The surveillance was based on regular blood sampling of susceptible species and antibody detection by a commercial competitive ELISA kit (cELISA). The performance of this cELISA was evaluated on both field results obtained during the 2001 surveillance campaigns and experimental results. ROC analyses were carried out using RT-PCR results as gold standard for determining the infection status of animals. From all these sets of data, cut-off values optimising the diagnostic accuracy of the test were computed. Their values ranged around the manufacturer's 50% threshold from 41% to 63%. The area under the ROC curve obtained from field data was 0.843 (95% CI: 0.762-0.923). In all our results, it appeared also that the specificity of the cELISA test was always perfect if the cut-off was at least at 80%. This cELISA test does not seem sufficient to diagnose BT disease in animals with BT-like symptoms. However, complementary data are needed to better estimate sensitivity and specificity values of this BT test for its use either as a diagnostic tool in infected areas or as a screening test in BT-free areas. The use and validity of RT-PCR results as gold standard are discussed. As the lack of suitable data strongly limited the applicable analyses, a discussion based on the OIE recommendations about test evaluation is initiated.     

Haematological values of Udah and Yankasa sheep in the northern Guinea savanna of Nigeria

Haematological values of Yankasa and Udah sheep were determined in three clinically healthy flocks and a fourth flock with mixed helminthiasis, predominantly haemonchosis. Values for Hb, PCV, RBC and WBC from the healthy flocks were similar. They were, however, lower than reported values for sheep in temperate zones except the WBC values which were higher. These parameters were lower in the infected flock and had a wider spread. It was concluded that haematological values from the clinically healthy flocks could serve as a baseline for interpreting haematological data from diseased local sheep. It is suggested that management and health status are more important than breed for differences in haematological values.