Diagnostic sensitivity and specificity of immunohistochemistry for the detection of rabies virus in domestic and wild animals in South Africa

We estimated the diagnostic sensitivity (DSe) and specificity (DSp) of an immunohistochemistry (IHC) protocol compared to the direct fluorescent antibody test (DFAT), which is the gold standard test for rabies diagnosis. We obtained brain samples from 199 domestic and wild animal cases (100 DFAT-negative, 99 DFAT-positive), by convenience sampling from 2 government-accredited rabies virus (RABV) testing laboratories in South Africa, between February 2015 and August 2017. Tissues that had been stored at 4-8°C for several days to weeks at the 2 accredited laboratories were formalin-fixed and paraffin-embedded. Nighty-eight cases tested IHC-positive using a polyclonal anti-RABV nucleoprotein antibody and a polymer detection system. The overall DSe and DSp for the RABV IHC test were 98% (95% CI: 93-100%) and 99% (95% CI: 95-100%), respectively. Domestic dogs accounted for 41 of 98 RABV IHC-positive cases, with the remainder in 4 domestic cats, 25 livestock, and 28 wildlife. Herpestidae species, including 7 meerkats and 9 other mongoose species, were the most frequently infected wild carnivores, followed by 11 jackals. Three cases in domestic dogs had discordant test results; 2 cases were IHC-/DFAT+ and 1 case was IHC+/DFAT-. Considering the implications of a false-negative rabies diagnosis, participating in regular inter-laboratory comparisons is vital, and a secondary or confirmatory method, such as IHC, should be performed on all submitted specimens, particularly negative cases with human contact history.

Peritoneal Dialysis-Associated Peritonitis Trends Using Medicare Claims Data, 2013-2017

RATIONALE & OBJECTIVE

The occurrence and consequences of peritoneal dialysis (PD)-associated peritonitis limit its use in populations with kidney failure. Studies of large clinical populations may enhance our understanding of peritonitis. To facilitate these studies we developed an approach to measuring peritonitis rates using Medicare claims data to characterize peritonitis trends and identify its clinical risk factors.

STUDY DESIGN

Retrospective cohort study of PD-associated peritonitis.

SETTING & PARTICIPANTS

US Renal Data System standard analysis files were used for claims, eligibility, modality, and demographic information. The sample consisted of patients receiving PD treated at some time between 2013 and 2017 who were covered by Medicare fee-for-service (FFS) insurance with paid claims for dialysis or hospital services.

EXPOSURES/PREDICTORS

Peritonitis risk was characterized by year, age, sex, race, ethnicity, vintage of kidney replacement therapy, cause of kidney failure, and prior peritonitis episodes.

OUTCOME

The major outcome was peritonitis, identified using ICD-9 and ICD-10 diagnosis codes. Closely spaced peritonitis claims (30 days) were aggregated into 1 peritonitis episode.

ANALYTICAL APPROACH

Patient-level risk factors for peritonitis were modeled using Poisson regression.

RESULTS

We identified 70,271 peritonitis episodes from 396,289 peritonitis claims. Although various codes were used to record an episode of peritonitis, none was used predominantly. Peritonitis episodes were often identified by multiple aggregated claims, with the mean and median claims per episode being 5.6 and 2, respectively. We found 40% of episodes were exclusively outpatient, 9% exclusively inpatient, and 16% were exclusively based on codes that do not clearly distinguish peritonitis from catheter infections/inflammation ("catheter codes"). The overall peritonitis rate was 0.54 episodes per patient-year (EPPY). The rate was 0.45 EPPY after excluding catheter codes and 0.35 EPPY when limited to episodes that only included claims from nephrologists or dialysis providers. The peritonitis rate declined by 5%/year and varied by patient factors including age (lower rates at higher ages), race (Black > White>Asian), and prior peritonitis episodes (higher rate with each prior episode).

LIMITATIONS

Coding heterogeneity indicates a lack of standardization. Episodes based exclusively on catheter codes could represent false positives. Peritonitis episodes were not validated against symptoms or microbiologic data.

CONCLUSIONS

PD-associated peritonitis rates decline over time and were lower among older patients. A claims-based approach offers a promising framework for the study of PD-associated peritonitis.

Diagnostic Specificity of Two Dengue Virus IgG ELISAs after Yellow Fever and Japanese Encephalitis Virus Vaccination

Dengue virus (DENV) antibody assays frequently cross-react with sera from individuals who have been infected with or vaccinated against related flaviviruses. The goal of this study was to determine the specificity of two DENV ELISAs with sera from individuals vaccinated against yellow fever virus (YFV) and Japanese encephalitis virus (JEV). The Panbio and the Novatec Dengue IgG ELISAs were tested with sera obtained 3-4 weeks or 0.5-6 years after YFV or JEV vaccination and the diagnostic specificity of the assays was determined. As controls, the sera were tested using DENV, YFV, JEV, Zika and West Nile virus neutralization assays. The diagnostic specificity of the Panbio and the Novatec ELISA with sera from YFV-vaccinated subjects was 98.2% and 88.2%, respectively. Cross-reactions were rare in the first 4 weeks despite high YFV-neutralizing antibody titers and were mostly found later. The specificity of the Panbio and Novatec assays with sera from JEV-vaccinated individuals was 100% and 92.9%. Cross-reactions occurred in the early time period after vaccination. The measurement values of the two ELISAs correlated strongly. Thus, the Panbio ELISA showed higher diagnostic specificity and may be suitable for seroprevalence studies in areas with high disease prevalence.

Evaluation of canine detection of covid-19 infected individuals under controlled settings

Reverse transcription polymerase chain reaction (RT‐PCR) is currently the standard diagnostic method to detect symptomatic and asymptomatic individuals infected with Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). However, RT‐PCR results are not immediate and may falsely be negative before an infected individual sheds viral particles in the upper airways where swabs are collected. Infected individuals emit volatile organic compounds in their breath and sweat that are detectable by trained dogs. Here, we evaluate the diagnostic accuracy of dog detection against SARS‐CoV‐2 infection. Fifteen dogs previously trained at two centres in Australia were presented to axillary sweat specimens collected from known SARS‐CoV‐2 human cases (n = 100) and non‐cases (n = 414). The true infection status of the cases and non‐cases were confirmed based on RT‐PCR results as well as clinical presentation. Across dogs, the overall diagnostic sensitivity (DSe) was 95.3% (95%CI: 93.1–97.6%) and diagnostic specificity (DSp) was 97.1% (95%CI: 90.7–100.0%). The DSp decreased significantly when non‐case specimens were collected over 1 min rather than 20 min (p value = .004). The location of evaluation did not impact the detection performances. The accuracy of detection varied across dogs and experienced dogs revealed a marginally better DSp (p value = .016). The potential and limitations of this alternative detection tool are discussed.

Comparison of diagnostic methods for Tetracapsuloides bryosalmonae detection in salmonid fish

Diagnostic accuracy of pathogen detection depends upon the selection of suitable tests. Problems can arise when the selected diagnostic test gives false-positive or false-negative results, which can affect control measures, with consequences for the population health. The aim of this study was to compare sensitivity of different diagnostic methods IHC, PCR and qPCR detecting Tetracapsuloides bryosalmonae, the causative agent of proliferative kidney disease in salmonid fish and as a consequence differences in disease prevalence. We analysed tissue from 388 salmonid specimens sampled from a recirculating system and rivers in the Czech Republic. Overall prevalence of T. bryosalmonae was extremely high at 92.0%, based on positive results of at least one of the above-mentioned screening methods. IHC resulted in a much lower detection rate (30.2%) than both PCR methods (qPCR32: 65.4%, PCR: 81.9%). While qPCR32 produced a good match with IHC (60.8%), all other methods differed significantly (p < .001) in the proportion of samples determined positive. Both PCR methods showed similar sensitivity, though specificity (i.e., the proportion of non-diseased fish classified correctly) differed significantly (p < .05). Sample preservation method significantly (p < .05) influenced the results of PCR, with a much lower DNA yield extracted from paraffin-embedded samples. Use of different methods that differ in diagnostic sensitivity and specificity resulted in random and systematic diagnosis errors, illustrating the importance of interpreting the results of each method carefully.

Utility of abdominal skin punch biopsy for detecting systemic amyloidosis

BACKGROUND

Early and accurate diagnosis of systemic amyloidosis (SA) is critical for optimal patient outcomes. Biopsy of clinically uninvolved skin and subcutaneous tissue including abdominal skin punch biopsy (ASPB) is often used as a surrogate for affected organ sampling. There is a lack of published data on the sensitivity and specificity of ASPB for diagnosing SA.

METHODS

Retrospective chart review between 2000 and 2020 of all ASPB was performed to diagnose SA. Amyloid deposition was confirmed by Congo red stain. Study group includes patients with histopathologically and clinically confirmed diagnosis of SA. Control group includes patients without histopathology of amyloid deposition and no clinical SA.

RESULTS

Forty-one patients meeting inclusion criteria were analyzed; 23 study group and 18 control group patients. The overall diagnostic sensitivity of ASPB was 43% (95% CI 23%-66%) and the specificity 100% (95% CI 81%-100%). The AL amyloidosis diagnostic sensitivity was 64% (95% CI 35%-87%). ASPB >10 mm in depth had 100% (95% CI 54%-100%) sensitivity compared to 24% for depth ≤10 mm (P = .002).

CONCLUSIONS

ASPB is a minimally invasive and highly specific method of diagnosing SA. It is particularly sensitive for diagnosing AL amyloidosis and the diagnostic sensitivity can be significantly improved with adequate biopsy depth and diameter.

Identification of Pru du 6 as a potential marker allergen for almond allergy

BACKGROUND

Oral food challenges have demonstrated that diagnosis of almond allergy based on extract-sIgE tests displays low specificity. Molecular allergy diagnosis is expected to improve accuracy, but its value in diagnosing almond allergy remains unknown. The aim of this study was to identify relevant almond allergens and examine their ability to improve almond allergy diagnosis.

METHODS

IgE-reactive proteins were purified from almond kernels. IgE binding to almond extract and the allergens was analyzed by quantitative ELISA using sera from 18 subjects with a proven almond allergy. The control group consisted of sera from 18 subjects allergic to peanut and/or tree nuts but tolerant to almond.

RESULTS

Three IgE-binding proteins were identified: legumin (Pru du 6), alpha-hairpinin (Pru du 8), and mandelonitrile lyase (Pru du 10). Positive IgE (≥0.35 kU/L) to almond extract showed 94% sensitivity but only 33% specificity. IgE to Pru du 6 maintained high sensitivity (83%) and provided superior specificity (78%). Sera from almond-allergic subjects had significantly higher IgE levels to almond extract (P < .0001) and Pru du 6 (P < .0001) than sera from tolerant donors. Sensitization to Pru du 6 was highly specific for almond allergy, while frequencies of sensitization to legumins from peanut, walnut, hazelnut, and cashew were similar in both groups. IgE to Pru du 8 and Pru du 10 was less sensitive (41% and 67%), but showed specificities of 100% and 61%.

CONCLUSION

The use of almond allergens markedly increases the diagnostic specificity compared to the extract. Pru du 6 is a potential new molecular marker for almond allergy.

Validation of real-time polymerase chain reaction versus conventional polymerase chain reaction for diagnosis of brucellosis in cattle sera

Background and Aim:

Different polymerase chain reaction (PCR) techniques have and are still being used for the direct detection of Brucella DNA in serum samples of different animal species and humans without being validated or properly validated, resulting in discrepancies. Thus, this study aimed to evaluate the diagnostic performance of the TaqMan Real-Time-PCR (RT-PCR) targeting the bcsp31 gene versus conventional PCR for the accurate diagnosis of brucellosis at the genus level in cattle sera.

Materials and Methods:

One hundred and eighty-four serum samples were collected from bacteriologically positive and negative cows with ages ranging from 1 to 5 years old at some infected private farms in the Nile Delta under quarantine measures as well as brucellosis free farms. These samples were classified into four groups after serological diagnosis and investigated by TaqMan RT-PCR and conventional PCR targeting the IS711 gene for Brucella DNA detection. The diagnostic performance characteristics of both PCR techniques were estimated considering the bacteriological results as a gold standard.

Results:

TaqMan RT-PCR revealed superiority over conventional PCR; it was able to detect Brucella DNA in 95% (67/70) and 89% (25/28) of the cattle sera samples belonging to Group 1 (serologically and bacteriologically positive) and Group 2 (serologically negative but bacteriologically positive), respectively. On evaluating the diagnostic performance, TaqMan RT-PCR showed superior diagnostic sensitivity (93.9%), diagnostic specificity (88.4%), performance index (182.3), almost perfect kappa agreement (0.825±0.042), strong positive correlation (r=0.826), high accuracy based on the receiver operating characteristic (ROC) curve, and area under the ROC curve (0.911) at p<0.05 and CI of 95%.

Conclusion:

A cattle serum sample is not the metric of choice for targeting Brucella genomic DNA by conventional PCR. The time-saving and rapid TaqMan RT-PCR method revealed a better diagnostic performance in the detection of Brucella DNA in cattle sera. Such performance offered by TaqMan RT-PCR may be considered a step toward the possibility of using such technology in the direct differentiation between Brucella-infected and -vaccinated cattle immunized by smooth vaccines from cattle sera using primers specific for such vaccines.

Is Levodopa Response a Valid Indicator of Parkinson's Disease?

BACKGROUND

The clinical diagnosis of Parkinson's disease (PD) requires the presence of parkinsonism and supportive criteria that include a clear and dramatic beneficial response to dopaminergic therapy. Our aim was to test the diagnostic criterion of dopaminergic response by evaluating its association with pathologically confirmed diagnoses in a large population of parkinsonian patients.

METHODS

We reviewed clinical data maintained in an electronic medical record from all patients with autopsy data who had been seen in the Movement Disorders Center at Washington University, St. Louis, between 1996 and 2018. All patients with parkinsonism who underwent postmortem neuropathologic examination were included in this analysis.

RESULTS

There were 257 unique parkinsonian patients with autopsy-based diagnoses who had received dopaminergic therapy. Marked or moderate response to dopaminergic therapy occurred in 91.2% (166/182) of those with autopsy-confirmed PD, 52.0% (13/25) of those with autopsy-confirmed multiple systems atrophy, 44.4% (8/18) of those with autopsy-confirmed progressive supranuclear palsy, and 1 (1/8) with autopsy-confirmed corticobasal degeneration. Other diagnoses were responsible for the remaining 24 individuals, 9 of whom had a moderate response to dopaminergic therapy.

CONCLUSION

A substantial response to dopaminergic therapy is frequent but not universal in PD. An absent response does not exclude PD. In other neurodegenerative disorders associated with parkinsonism, a prominent response may also be evident, but this occurs less frequently than in PD. © 2020 International Parkinson and Movement Disorder Society.

Role of diffusion-weighted imaging in the diagnosis of cerebral venous thrombosis

OBJECTIVE

To evaluate the hyperintense signal (HIS) performance on diffusion-weighted imaging (DWI) in diagnosing cerebral venous thrombosis (CVT).

METHODS

Seventy-eight patients with CVT hospitalized from January 2004 to January 2015 were retrospectively studied alongside 78 controls without intracranial organic diseases. Diagnostic accuracy indices of HIS on DWI or T2-weighted imaging (T2WI) to diagnose CVT at different sites and states were analyzed.

RESULTS

The overall sensitivity of HIS on DWI for the diagnosis of CVT was significantly lower than that of HIS on T2WI (34.6% vs. 79.5%). HIS on T2WI was more sensitive than HIS on DWI in detecting thrombosis, especially in the superior sagittal sinus and transverse sinus. HIS on DWI was inversely related to the time between disease onset and imaging. Compared with HIS on T2WI, combining HIS on DWI and T2WI did not increase the sensitivity for detecting CVT. HIS on DWI was not detected in the control group, but HIS on T2WI was detected in 26.3% of control individuals. The specificity of HIS on DWI for CVT was higher than that of HIS on T2WI (97.4% vs. 76.9%).

CONCLUSION

HIS on DWI has a lower sensitivity, but a higher specificity, than HIS on T2WI for diagnosing CVT.

Examining the Criterion Validity and Diagnostic Specificity of Self-Report Measures of Narcissism and Mania

We examined the validity of self-report measures of narcissism and mania by relating them to interview-based ratings of psychopathology. Narcissism scales were taken from the Narcissistic Personality Inventory (NPI), the Personality Diagnostic Questionnaire-4+, and the Short Dark Triad. Mania measures included the Altman Self-Rated Mania Scale (ASRM) and scales taken from the Hypomanic Personality Scale (HPS) and Expanded Version of the Inventory of Depression and Anxiety Symptoms. Our analyses addressed two key issues. The first issue was whether these scales demonstrated significant criterion validity (e.g., whether the HPS scales correlated significantly with interview ratings of mania). The second issue was whether they displayed specificity to their target constructs (e.g., whether the NPI scales correlated more strongly with ratings of narcissistic personality disorder than with other forms of psychopathology). All of the narcissism scales-including all three NPI subscales-correlated significantly with interview ratings of narcissistic personality disorder and showed considerable evidence of diagnostic specificity. Most of the mania scales also displayed good criterion validity and diagnostic specificity. However, two measures-the ASRM and the HPS Social Vitality subscale-had weak, nonsignificant associations with interview ratings of manic episodes; these findings raise concerns regarding their validity as specific indicators of mania.

Field Evaluation of Diagnostic Test Sensitivity and Specificity for Salmonid Alphavirus (SAV) Infection and Pancreas Disease (PD) in Farmed Atlantic salmon (Salmo salar L.) in Norway Using Bayesian Latent Class Analysis

Salmonid alphavirus (SAV) is the OIE-listed, viral cause of pancreas disease (PD) in farmed Atlantic salmon. SAV is routinely detected by PCR–methods while typical histopathological lesions are additionally used to confirm the diagnosis. Field evaluation of diagnostic test performance is essential to ensure confidence in a test's ability to predict the infection or disease status of a target animal. For most tests used in aquaculture, characteristics like sensitivity (Se) and specificity (Sp) at the analytical level may be known. Few tests are, however, evaluated at the diagnostic level according to the OIE standard. In the present work, we estimated diagnostic test sensitivity (DSe) and diagnostic test specificity (DSp) for five laboratory tests used for SAV detection. As there is no gold standard, the study was designed using Bayesian latent class analysis. Real-time RT-PCR, cell culture, histopathology, virus neutralization test, and immunohistochemistry were compared using samples taken from three different farmed Atlantic salmon populations with different infection status; one population regarded negative, one in an early stage of infection, and one in a later stage of infection. The average fish weight in the three populations was 2.0, 1.6, and 1.5 kg, respectively. The DSe and DSp of real-time RT-PCR is of particular interest due to its common use as a screening tool. The method showed high DSe (≥0.977) and moderate DSp (0.831) in all 3-populations models. The results further suggest that a follow-up test of serum samples in real-time RT-PCR negative populations may be prudent in cases where epidemiological information suggest a high risk of infection and where a false negative result is of high consequence. This study underlines the need to choose a test appropriate for the purpose of the testing. In the case of a weak positive PCR-result, a follow-up test should be conducted to verify the presence of SAV. Cell culture showed high DSe and DSp and may be used to verify viral presence.

Assessment of reproducibility of a VP7 Blocking ELISA diagnostic test for African horse sickness

The laboratory diagnosis of African horse sickness (AHS) is important for: (a) demonstrating freedom from infection in a population, animals or products for trade (b) assessing the efficiency of eradication policies; (c) laboratory confirmation of clinical diagnosis; (d) estimating the prevalence of AHS infection; and (e) assessing postvaccination immune status of individual animals or populations. Although serological techniques play a secondary role in the confirmation of clinical cases, their use is very important for all the other purposes due to their high throughput, ease of use and good cost-benefit ratio. The main objective of this study was to support the validation of AHS VP7 Blocking ELISA up to the Stage 3 of the World Animal Health Organization (OIE) assay validation pathway. To achieve this, a collaborative ring trial, which included all OIE Reference Laboratories and other AHS-specialist diagnostic centres, was conducted in order to assess the diagnostic performance characteristics of the VP7 Blocking ELISA. In this trial, a panel of sera of different epidemiological origin and infection status was used. Through this comprehensive evaluation we can conclude that the VP7 Blocking ELISA satisfies the OIE requirements of reproducibility. The VP7 Blocking ELISA, in its commercial version is ready to enter Stage 4 of the validation pathway (Programme Implementation). Specifically, this will require testing the diagnostic performance of the assay using contemporary serum samples collected during control campaigns in endemic countries.

Overinterpretation and Overtreatment of Low-Titer Antibodies Against Contactin-Associated Protein-2

Antibodies (abs) against neural or glial antigens have become important diagnostic markers of autoimmune encephalitides. A key requirement for interpretation of any test in clinical medicine is specificity. In this work, a 35-year-old female patient with low-titer contactin-associated protein-2 abs not satisfying clinical criteria of autoimmune encephalitis is reported. The patient had a recurrent depressive disorder and, at the time of the ab study, a moderate depressive episode. Overinterpretation and misinterpretation of patient’s complaints and paraclinical study results fueled the idea of an autoimmune encephalitis. It is suggested to check patients with supposedly positive ab test results critically for clinical criteria, titer cutoffs, and ab-typical epidemiological features like age and sex.

Herniation of crypts in hyperplastic polyp and sessile serrated adenoma: a prospective study

Presence of colonic crypts in submucosa was previously termed as herniation of crypts, pseudoinvasion, epithelial-misplacement, or inverted hyperplastic-polyp. It is considered as an important criterion for diagnosing sessile serrated adenoma (SSA), which links to a higher risk of synchronous and future colorectal cancers compared with hyperplastic polyp (HP). Here, we aimed to study the frequencies, diagnostic specificity and synchronous neoplasms of herniation of crypts in HP and SSA. We prospectively included all HP and SSA cases and 514 randomly-selected colorectal polyps of normal histology diagnosed from 2013 to 2015 at our institution. We calculated the frequencies of herniation of crypts by histology, sex, age, size, race, location, prior polyp-history and synchronous neoplasms (including colorectal cancers and adenomas). Binary and ordinal (ordered) logistic regression analyses were used to identify potential associations. Among the 2,560 colorectal polyps in the subjects with average-risk of colorectal cancer, the frequencies of herniation of crypts were 1.79% (10/559) in SSA, 0.2% (3/1487) in HP and 0% (0/514) in polypoid normal tissue. The specificity of herniation of crypts for diagnosing serrated polyp (HP and SSA versus normal tissue) was 100% (514/514), but its sensitivity was 0.64% (13/2046), while the specificity of herniation of crypts for diagnosing SSA (versus HP and polypoid normal tissue) was 99.85% (1998/2001) and its sensitivity was 1.79% (10/559). Our multivariate analyses identified an independent association between herniation of crypts and diagnosis of SSA (Odds ratio [OR]=9.37, P=0.015 for versus HP and normal tissue, and OR=11.47, P=0.009 for versus HP). We also found that herniation of crypts in SSA and HP did not independently link to race or synchronous neoplasms (including cancers and adenomas). In summary, our data show that, while herniation of crypts is rare, its presence is highly suggestive of SSA.

Diagnostic specificity of the African swine fever virus antibody detection enzyme-linked immunosorbent assay in feral and domestic pigs in the United States

African swine fever (ASF) is a highly contagious haemorrhagic disease of pigs that has the potential to cause mortality nearing 100% in naïve animals. While an outbreak of ASF in the United States' pig population (domestic and feral) has never been reported, an introduction of the disease has the potential to cause devastation to the pork industry and food security. During the recovery phase of an outbreak, an antibody detection diagnostic assay would be required to prove freedom of disease within the previously infected zone and eventually nationwide. Animals surviving an ASF infection would be considered carriers and could be identified through the persistence of ASF viral antibodies. These antibodies would demonstrate exposure to the disease and not vaccination, as there is no ASF vaccine available. A well-established commercial enzyme-linked immunosorbent assay (ELISA) detects antibodies against ASF virus (ASFV), but the diagnostic specificity of the assay had not been determined using serum samples from the pig population of the United States. This study describes an evaluation of the World Organization for Animal Health (OIE)-recommended Ingezim PPA COMPAC ELISA using a comprehensive cohort (n = 1791) of samples collected in the United States. The diagnostic specificity of the assay was determined to be 99.4% (95% confidence interval (CI): [98.9, 99.7]). The result of this study fills a gap in understanding the performance of the Ingezim PPA COMPAC ELISA in the ASF naïve pig population of the United States.

Sensitivity and specificity of real-time PCR and bacteriological culture for francisellosis in farm-raised Nile tilapia (Oreochromis niloticus L.)

Despite the worldwide occurrence of Francisella noatunensis subsp. orientalis (Fno) infection in farmed tilapia, sensitivity and specificity estimates of commonly used diagnostic tests have not been reported. This study aimed to estimate the sensitivity and specificity of bacteriological culture and qPCR to detect Fno infection. We tested 559 fish, sampled from four farms with different epidemiological scenarios: (i) healthy fish in a hatchery free of Fno; (ii) targeted sampling of diseased fish with suggestive external clinical signs of francisellosis during an outbreak; (iii) convenience sampling of diseased and clinically healthy fish during an outbreak; and (iv) sampling of healthy fish in a cage farm without a history of outbreaks, but with francisellosis reported in other farms in the same reservoir. The qPCR had higher median sensitivity (range, 48.8-99.5%) than culture (range, 1.6-74.4%). Culture had a substantially lower median sensitivity (1.6%) than qPCR (48.8%) to detect Fno in carrier tilapia (farm 4). Median specificity estimates for both tests were >99.2%. The qPCR is the superior test for use in surveillance and monitoring programmes for francisellosis in farmed Nile tilapia, but both tests have high sensitivity and specificity which make them fit for use in the diagnosis of Fno outbreaks.

"Prolonged grief disorder" and "persistent complex bereavement disorder", but not "complicated grief", are one and the same diagnostic entity: an analysis of data from the Yale Bereavement Study

There exists a general consensus that prolonged grief disorder (PGD), or some variant of PGD, represents a distinct mental disorder worthy of diagnosis and treatment. Nevertheless, confusion remains over whether different names and proposed symptom criteria for this disorder identify the same or different diagnostic entities. This study aimed to determine whether PGD, complicated grief (CG), and persistent complex bereavement disorder (PCBD) as described by the DSM-5 are substantively or merely semantically different diagnostic entities. Data were derived from the Yale Bereavement Study, a longitudinal community-based study of bereaved individuals funded by the US National Institute of Mental Health, designed explicitly to evaluate diagnostic criteria for disordered grief. The results suggested that the difference between PGD and PCBD is only semantic. The level of agreement between the original PGD test, a new version of the PGD test proposed for ICD-11 and the PCBD test was high (pairwise kappa coefficients = 0.80-0.84). Their estimates of rate of disorder in this community sample were similarly low (∼10%). Their levels of diagnostic specificity were comparably high (95.0-98.3%). Their predictive validity was comparable. In contrast, the test for CG had only moderate agreement with those for PGD and PCBD; its estimate of rate of disorder was three-fold higher (∼30%); its diagnostic specificity was poorer, and it had no predictive validity. We conclude that PGD, PCBD and proposed ICD-11, but not CG, symptom-diagnostic tests identify a single diagnostic entity. Ultimately, brief symptom-diagnostic tests, such as the one proposed here for ICD-11, may have the greatest clinical utility.

Autism and Classical Eyeblink Conditioning: Performance Changes of the Conditioned Response Related to Autism Spectrum Disorder Diagnosis

Changes in the timing performance of conditioned responses (CRs) acquired during trace and delay eyeblink conditioning (EBC) are presented for diagnostic subgroups of children having autism spectrum disorder (ASD) aged 6-15 years. Children diagnosed with autistic disorder (AD) were analyzed separately from children diagnosed with either Asperger's syndrome or Pervasive developmental disorder (Asp/PDD) not otherwise specified and compared to an age- and IQ-matched group of children who were typically developing (TD). Within-subject and between-groups contrasts in CR performance on sequential exposure to trace and delay EBC were analyzed to determine whether any differences would expose underlying functional heterogeneities of the cerebral and cerebellar systems, in ASD subgroups. The EBC parameters measured were percentage CRs, CR onset latency, and CR peak latency. Neither AD nor Asp/PDD groups were impaired in CR acquisition during trace or delay EBC. Both AD and Asp/PDD altered CR timing, but not always in the same way. Although the AD group showed normal CR timing during trace EBC, the Asp/PDD group showed a significant 27 and 28 ms increase in CR onset and peak latency, respectively, during trace EBC. In contrast, the direction of the timing change was opposite during delay EBC, during which the Asp/PDD group showed a significant 29 ms decrease in CR onset latency and the AD group showed a larger 77 ms decrease in CR onset latency. Only the AD group showed a decrease in CR peak latency during delay EBC, demonstrating another difference between AD and Asp/PDD. The difference in CR onset latency during delay EBC for both AD and Asp/PDD was due to an abnormal prevalence of early onset CRs that were intermixed with CRs having normal timing, as observed both in CR onset histograms and mean CR waveforms. In conclusion, significant heterogeneity in EBC performance was apparent between diagnostic groups, and this may indicate that EBC performance can report the heterogeneity in the neurobiological predispositions for ASD. The findings will inform further explorations with larger cohorts, different sensory modalities, and different EBC paradigms and provide a reference set for future EBC studies of children having ASD and non-human models.

Pregnancy rates of beef cattle are not affected by Campylobacter fetus subsp. venerealis real-time PCR-positive breeding sires in New Zealand

AIMS

Campylobacter fetus subspecies venerealis (C. fetus venerealis) is the causal agent of bovine genital campylobacteriosis, a venereal disease that is asymptomatic in bulls but responsible for reproductive wastage in female cattle. In New Zealand, a commercial real-time PCR assay was introduced in 2007 to identify the DNA of this pathogen in preputial scrapings; however, concerns were raised about the specificity of the test following anecdotal reports of a high number of test-positive bulls with no apparent relationship to reproductive performance. The objective of this study, therefore, was to examine the association between real-time PCR assay results from beef breeding bulls and pregnancy rates in beef herds using these bulls.

METHODS

Veterinarians from four veterinary practices selected beef cattle herds with relatively high and low pregnancy rates between December 2008 and February 2009. Preputial scrapings were collected from bulls used for mating in those herds. Samples were tested using the real-time PCR assay under consideration. Bivariable and multivariable analyses were used to assess the relationship between pregnancy rates in each mob (15-month-old heifers, 27-month-old heifers and mixed-age cows) and the percentage of real-time PCR-positive bulls in each mob.

RESULTS

Sixty-four (28.8%) of 222 bulls tested positive, 130 (58.6%) tested negative, and 28 (12.6%) returned an inconclusive result to the real-time PCR assay. The percentage of bulls testing real-time PCR-positive in these mobs was not associated with pregnancy rates (p=0.757) after controlling for mob, average body condition score of cows, cow to bull ratio, length of the mating period, and farm.

CONCLUSION

Real-time PCR assay results were not associated with pregnancy rates, suggesting that the specificity of the real-time PCR assay was too low to be used to reliably detect C. fetus venerealis. This study adds to a growing body of evidence indicating that C. fetus venerealis strains are either absent from, or present at clinically insignificant levels of endemicity among, beef breeding herds in New Zealand.

CLINICAL SIGNIFICANCE

The real-time PCR assay that was assessed in this study should not be used for the detection of C. fetus venerealis in bulls or for investigations of low conception rates in cattle in New Zealand. During the course of this survey, sequencing analysis of an apparent C. fetus venerealis isolate from the intestines of a Friesian bull turned out to be Campylobacter hyointestinalis. As a consequence, this real-time PCR assay for C. fetus venerealis is no longer being offered by diagnostic laboratories in New Zealand.

External quality assessment of tumour marker analysis: state of the art and consequences for estimating diagnostic sensitivity and specificity

This review shows the current analytical quality for the following analytes used as tumour markers in the external quality assessment (EQA)-programmes of Instand e.V., a national EQA-organiser in Germany: Corticotropin (ACTH), growth hormone (GH, hGH), prolactin (PRL), chorionic gonadotropin (CG, hCG), calcitonin (CT, hCT), thyroglobulin (Tg), carcinoembryonic antigen (CEA), CA-Antigens 125, 72-4, 15-3 and 19-9, alpha foetoprotein (AFP) and prostate-specific antigen (PSA). The results from the participants show a large variation in the precision of the methods used as well as in the comparability of results between methods for the same analyte. In general, the hormones used as tumour markers show better performance than the "CA-markers", which are often inadequately standardised and defined. In the case of one CA-marker (CA 72-4/TAG 72-4), the differences between the lowest kit median concentration and highest kit median concentration for one sample pair were 440% and 580%. The corresponding figures for ACTH were 123% and 156% and for CEA 180% and 184%. The classical tumour markers such as carcinoembryonic antigen (CEA) and alpha foetoprotein (AFP) performed markedly better than the CA-markers and PSA with regards to both inter- and intra-method comparability. The inter-laboratory precision for a given kit and marker was acceptable in many cases. The results show that only results from the same kit/method for each tumour marker can be used for cumulative or time-dependent comparison of results - for example pre-operative and post-operative follow up. In the case of prostate specific antigen (PSA), the kits used for free and total PSA must come from the same producer, if the generally accepted ratios are to have any diagnostic value. The need for kit- and laboratory-specific reference ranges and cut-off values for setting diagnostic specificity and sensitivity is highlighted from the EQA-results. The situation for inter-method comparability for the CA-Markers has not improved over the past decade. With the exception of calcitonin for detecting medullary thyroid carcinoma, chorionic gonadotropin in germ-cell tumours in men and thyroglobulin after total thyroidectomy, none of the remaining analytes appear to be suitable for screening purposes.

The Limulus Amoebocyte Lysate test: detection of endotoxin in plasma of swine and cattle. II. In vivo investigations

Endotoxin was detected by the LAL test in the plasma of swine and cattle following in vivo injection of endotoxin in order to evaluate the applicability of the test in veterinary medicine for detection of endotoxemia.

Clinical symptoms of endotoxemia occurred after the injection into 3 swine of 0.10–0.25 mg endotoxin/100 kg bwt and after the infusion during 1–1½ h of 2.0–2.2 mg endotoxin/100 kg bwt into 3 calves. The concentration of endotoxin detected by the LAL test in the experimental animals ranged from 0.15 ng to 6.0 ng endotoxin per ml crude plasma. As positive LAL reactions were obtained only in close connection to the administration of endotoxin, clearance of endotoxin to levels below the sensitivity of the test was fast. In spite of the fast clearance, light symptoms of endotoxemia could be seen as long as 24 h after the last sample showing a positive test result. The applied technique for LAL analysis on blood, therefore, was not adequate for detection of endotoxin at sufficiently low concentrations and some possibilities of improving the technique are discussed.

Though leukocytosis were found not to influence the outcome of the LAL test on blood, leukocytic mediators released by endotoxin or endotoxin-derived injuries may still have caused the persistence of the symptoms of endotoxemia, and this question is disputed in relation to the benefit of improving the technique.

Especielly in the veterinary clinic, great precautions are necessary to obviate false positive test samples resulting from, e.g., external contamination or transient stress caused by excitement, and it is concluded that the possible application of the LAL test for detection of endotoxemia in veterinary medicine is restricted to surveillance of hospitalized animals and to research purposes.