Demographic and Environmental Risk Factors for Exposure to Lawsonia intracellularis in Horses in Israel

Equine proliferative enteropathy (EPE) is an enteric disease of foals that is caused by Lawsonia intracellularis. Clinical cases have been reported worldwide; however, data regarding the epidemiology of L. intracellularis in horses are scarce. Thus far, L. intracellularis has not been reported in the Middle East. The objectives of this study were to determine whether the causative agent of EPE exists in horses in Israel and in the Palestinian Authority and to define environmental and demographic risk factors for exposure. Fecal and serum samples were collected from horses from various regions of the country. The presence of L. intracellularis in horses in Israel was determined by real-time polymerase chain reaction (PCR), and seroprevalence was determined by enzyme-linked immunosorbent assay. One fecal sample of 136 tested (0.7%), was PCR positive. Sixty-seven sera samples (30.5%) of 220 horses in sentinel farms had anti-L. intracellularis antibodies. Low seroprevalence was found in foals both from Israel and from the Palestinian Authority (4.2% and 13.3%, respectively). In logistic regression models, geographical locations, management type, and age were found to be significant risk factors associated with seroprevlaence to L. intracellularis. No significant correlation was found between environmental variables and L. intracellularis seroprevalence after controlling for management type. These results support the existence of L. intracellularis in horses in both Israel and the Palestinian Authority. The reasons for the relatively low prevalence are currently not known and may be the result of different management, low exposure to free-living animals, and differences in environmental variables affecting the bacterial burden.     

Serological markers of Bornavirus infection found in horses in Iceland

Background

In a stable of eight horses in Northern Iceland, six horses presented with clinical signs, such as ataxia and reduced appetite, leading to euthanasia of one severely affected horse. Serological investigations revealed no evidence of active equine herpes virus type 1 infection, a common source of central nervous system disease in horses, nor equine arteritis virus and West Nile virus. Another neurotropic virus, Borna disease virus, was therefore included in the differential diagnosis list.

Findings

Serological investigations revealed antibodies against Borna disease virus in four of five horses with neurological signs in the affected stable. One horse without clinical signs was seronegative. Four clinically healthy horses in the stable that arrived and were sampled one year after the outbreak were found seronegative, whereas one of four investigated healthy horses in an unaffected stable was seropositive.

Conclusions

This report contains the first evidence of antibodies to Borna disease virus in Iceland. Whether Borna disease virus was the cause of the neurological signs could however not be confirmed by pathology or molecular detection of the virus. As Iceland has very restricted legislation regarding animal imports, the questions of how this virus has entered the country and to what extent markers of Bornavirus infection can be found in humans and animals in Iceland remain to be answered.     

黔东南州山羊布鲁氏菌病血清学调查研究

为了掌握黔东南州山羊布鲁氏菌病的感染情况,为制定防治措施提供科学依据,2012年采集了4个县的部分规模养羊场血清共1461份（A县541份、B县410份、C县368份、D县142份）,先用琥红平板试验进行检测,将检出的阳性血清再用试管凝集试验进行确定.结果：A县阳性数43份,阳性率为7.94％,B县阳性数99份,阳性率为24.14％;C县阳性数45份,阳性率为12.23％;D县阳性数12份,阳性率为8.45％.根据检测结果,对检出的阳性羊进行淘汰和无害化处理,并采取了一系列的综合防治措施.     

Naturally acquired Lawsonia intracellularis infection in pigs studied from weaning to slaughter by indirect immunofluorescence antibody test and polymerase chain reaction on faeces

The course of naturally acquired Lawsonia intracellularis infection was studied in 41 pigs by testing blood and faeces samples collected four to seven times from before weaning to slaughter 5 months old. At slaughter, a sample of ileum was taken for histopathology. In the first sampling when the pigs were 2-4 weeks old maternally derived IgG against L. intracellularis was demonstrated by immunofluorescence antibody test in nine pigs whereas the bacterium was detected by PCR in faeces from six pigs. The maternally derived antibodies did not prevent pigs from becoming infected as seven pigs later on shed and/or were seropositive for L. intracellularis. The lowest prevalence of L. intracellularis was observed in 6-13 weeks old pigs and it seemed as though L. intracellularis in early infected pigs only activates a minor antibody response. At slaughter 66% of the pigs were found positive by immunofluorescence antibody test compared to 24% by immunohistochemistry on ileal samples. Thus, applied at the time of slaughter the antibody test appeared to be a highly sensitive ante-mortem diagnostic tool for identifying L. intracellularis exposed pigs with or without current proliferative enteropathy.     

Survival analysis on aggregate data to assess time to sero-conversion after experimental infection with Bovine Leukemia virus

Bovine Leukemia virus (BLV) is a ubiquitous retrovirus that affects mainly cattle. Knowledge of the precise moment of infection is fundamental for identification and evaluation of factors related to BLV transmission. Systematic reviews and meta-analyses provide good evidence on the effects of medical interventions. The objectives were to estimate time to sero-conversion after experimental infection using data from retrieved literature and to detect factors that may influence the length of that interval using survival analysis on pooled data.

An analysis using aggregate data from 36 studies totalling 438 observations was performed. From this, four sets were created and analysed by interval-censored accelerated failure time models (AFT) with different distributions (exponential, Weibull, log-logistic, lognormal and generalized gamma), and some variants of the Cox model (Andersen-Gill, smoothing splines) with and without a frailty effect.

The AFT gamma model fit best and the estimated median time to sero-conversion in the null model was 57 days (95% confidence interval (CI): 49; 75) using all data and 47 days (95% CI: 39; 55) when only studies using experimental inoculation were considered. Some factors were consistently associated with time to sero-conversion. These included exposure by animal-to-animal contact (resulting in a seven-fold increase in time to sero-conversion compared to direct inoculation), diagnostic method to detect sero-conversion (time to sero-conversion was 1.4 times shorter when AGID was used compared to ELISA), and transmission by insect bites (biological media) delayed sero-conversion 2.3 times compared transmission via needles or other inanimate media.

After fitting a frailty Cox model, results showed that sero-conversion in susceptible animals after infection using donors, in which presence of virus before the experiment started was confirmed, increased the hazard of sero-conversion two times in comparison with donors in which virus presence was not confirmed before start of the experiment. Inoculation with blood decreased the hazard 2.5 times in comparison with lymphocyte suspensions. Heterogeneity due to different research groups was also present. Finally, a Cox model with smoothing splines contained three variables: research group, route of inoculation and a non-linear spline for infective dose. In conclusion, it can be stated some factors that influence the time to sero-conversion were identified and quantified and that a moderate influence of research centre existed. These results may contribute to the estimation of the most probable times of infection in field conditions and in a better evaluation of control measures.     

番茄花叶病毒番茄分离物与烟草花叶病毒蚕豆分离物生物学、血清学比较及PCR特异性检测

 对番茄花叶病毒番茄分离物(ToMV-To-S1)和烟草花叶病毒蚕豆分离物(TMV-B935A)进行了生物学和血清学比较。人工接种6科20种植物,这两个分离物均能侵染其中的3科14种植物,但在普通烟(白肋烟、黄苗榆)上的症状差异较大,前者在这些植物上引起局部症状,后者为系统症状。在琼脂双扩散试验中,两者与ToMV-To-S1抗血清和4种TMV抗血清均形成沉淀线,但沉淀线之间产生刺角,说明ToMV-To-S1和TMV-B935A虽有血清关系,但亦有差异。胶内交叉吸附试验也证明两者之间有血清学差异。根据已报道的ToMV-L株系和TMVU1株系CP基因的3'端非编码区序列设计了ToMV和TMV特异引物,采用PCR方法,这些引物能够特异性的检测区分ToMV-To-S1和TMV-B935A。     

Validation of a competitive ELISA for diagnosis of Brucella melitensis infection in sheep and goats

A competitive enzyme-linked immunosorbent assay (cELISA) was validated for the serodiagnosis of Brucella melitensis infection in small ruminants using 2108 positive and 2154 negative reference sera from sheep and goats. The optimum cut-off values, offering the highest diagnostic sensitivity (DSn) and diagnostic specificity (DSp), determined by receiver operating characteristic analysis, were at 23.6%, 21.8% and 25.0% inhibition of the conjugate control for sheep, goats and both species, respectively. The DSns of the cELISA for sheep, goats and both species at these cut-off values were 89.2% (95% confidence interval 87.1-91.1%), 74.0% (95% CI 71.4-76.5%) and 77.9% (95% CI 76.1-79.7%), whereas DSps were 96.4% (95% CI 95.2-97.4%), 92.9% (95% CI 91.1-94.3%) and 97.2% (95% CI 96.4-97.8%), respectively. Compared to cELISA, indirect ELISA and fluorescence polarisation assay have higher DSns and DSps. However, the results obtained with the cELISA were in good agreement with those of the complement fixation test (CFT) under field conditions using 5735 sheep and goat sera. The cELISA can be used as an alternative to the CFT for diagnosing B. melitensis infection in small ruminants.     

Accuracy of two commercial enzyme-linked immunosorbent assays for the detection of antibodies to Salmonella spp. in slaughter pigs from Canada

Large discrepancies are usually found when different ELISAs for the diagnosis of pig salmonellosis are compared. Thus, our main goal was to estimate the diagnostic accuracy through Bayesian approaches of two commercial assays (Svanovir™ “test A” and HerdCheck™ “test B”) for the detection of antibodies to Salmonella spp. in slaughter pigs. Previously, we estimated the agreement between both tests and their relative sensitivity (Se) and specificity (Sp) with respect to bacteriology on caecal content and ileocaecal lymph nodes. Test A, at a cut-off OD% ≥20%, indicated higher prevalence than test B (OD% ≥10%) (14.6% vs. 8.6%). Relative Se with respect to overall bacteriology was low (≈30%) and similar for both tests, but the relative Sp was significantly lower for test A compared to B (88% vs. 95%). Both tests failed to detect some pigs infected with Salmonella serogroups B and C₁, which they were supposed to identify. In general, tests showed only fair-to-moderate agreement when they were compared (kappa: 0.41). In the Bayesian models, Se of test A varied between 63% and 77%, while Se of test B was 73%. Sp of A was always lower than that of test B (89% vs. 95%). The implications derived from the use of these imperfect serological tests will have to be accounted for in large-scale Salmonella-control programs.     

Antigen and antibody testing for the diagnosis of blastomycosis in dogs

BACKGROUND: Early diagnosis and treatment are associated with an improved prognosis in blastomycosis. The diagnosis of blastomycosis may be missed by cytology, histopathology, culture, or serology. An enzyme immunoassay (EIA) for detection of Blastomyces dermatitidis galactomannan antigen in body fluids has been used for rapid diagnosis of blastomycosis in humans. HYPOTHESIS: Measurement of Blastomyces antigen in urine or serum by the MVista Blastomyces antigen EIA is more sensitive than measurement of anti-Blastomyces antibodies for diagnosis of blastomycosis in dogs. METHODS: Serum and urine samples from 46 dogs with confirmed blastomycosis were tested for Blastomyces antigen and serum was tested for anti-Blastomyces antibodies. RESULTS: The sensitivity for the detection of antigen in urine was 93.5% and it was 87.0% in serum. The sensitivity of antibody detection by agar gel immunodiffusion (AGID) was 17.4% and it was 76.1% by EIA. Antigen and antibody decreased during itraconazole treatment. CONCLUSIONS AND CLINICAL IMPORTANCE: Antigen detection is a more sensitive test for diagnosis of blastomycosis than antibody testing by AGID, the only commercially available method. Antigen concentrations decreased with treatment.     

Cross-sectional serological survey on gastrointestinal and lung nematode infections in first and second-year replacement stock in the netherlands: relation with management practices and use of anthelmintics

A cross-sectional survey was carried out on 86 farms randomly distributed in The Netherlands. After housing following the first and the second grazing season (FGS and SGS) serum samples were collected to determine IgG levels against Cooperia oncophora and Dictyocaulus viviparus, and the pepsinogen content. A questionnaire was used to inquire on grazing management practices and the use of anthelmintic drugs. On 80.7 and 60.2% of the farms FGS and SGS animals, respectively, were treated at least once with an anthelmintic drug. The percentage for the SGS animals indicates that the use of anthelmintic drugs in those animals has increased enormously over the last 10–15 years. Generally, parasitic nematode control in the FGS is good on most farms, but it can be characterised as being overprotective. There is a tendency that if anthelmintic drugs are used in the FGS they also are used more often in the SGS. On 12 farms (14%), no anthelmintic drugs were given in the FGS and the SGS. These farms did not differ from the others with respect to management practices in any obvious way. The serological results were in general very low, indicating low levels of exposure to gastrointestinal nematode infection in both FGS and SGS animals. This was not surprising in view of the good to high level of nematode control practices reported by the farmers. Although not statistically significant, a consistent result was that serological results for the SGS animals were more often positive or on average higher on those farms where FGS parasite control tended to be excessive. For D. viviparus, a prevalence rate of 41% positive farms was found. Following comparison with previous data, it is speculated that lungworm (sero-)prevalence in replacement stock may be declining as a result of continuing high levels of parasite control in replacement stock. It is concluded that the results confirm previous surveys, lending support to the conclusion that parasitic nematode control on Dutch dairy farms, certainly in FGS calves, is good but tends to be overprotective.