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Kelly ET, McAloon CG, O'Grady L, Duane M, Somers JR, Beltman ME. Reproductive tract disease in Irish grazing dairy cows: Retrospective observational study examining its association with reproductive performance and accuracy of 2 diagnostic tests. J Dairy Sci 2022; 105:5471-5492. [PMID: 35450719 DOI: 10.3168/jds.2021-21404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Accepted: 02/19/2022] [Indexed: 11/19/2022]
Abstract
The detection of reproductive tract disease (RTD) 3 wk postpartum is important because of its effect on subsequent reproductive outcomes. Numerous methods for the diagnosis of RTD are described, some of which are more practical and instantaneous in terms of diagnosis. Two of these methods involve identification of purulent vaginal discharge (PVD) and evidence of ultrasonographic uterine changes indicative of endometritis (UE). The objectives of our retrospective observational study were (1) to assess the association of PVD or UE score at the prebreeding examination (PBE) with the hazard of pregnancy within the subsequent breeding season; (2) to determine the test sensitivity (Se) and specificity (Sp) at the point of sampling of both tests using a Bayesian latent class model; and (3) to determine the effect of varying positivity thresholds on test accuracy. To achieve these objectives, we analyzed an initial data set of 5,049 PBE from 2,460 spring-calved cows in 8 herds between 2014 and 2018. Each PBE was conducted once between 25 and 86 d in milk. At each PBE, vaginal discharge was obtained with a Metricheck device (Simcro) whereas uterine contents were assessed using transrectal ultrasonography. Purulent vaginal discharge was scored on a scale of 0 to 3 depending on discharge character, and UE was scored on a scale of 0 to 4 depending on the presence and consistency of intraluminal fluid. Cows with scores of ≥2 in either test had received treatment. Fertility data were available from 4,756 PBE after data exclusion. The association between PVD or UE score at the PBE and subsequent hazard of pregnancy was analyzed using a Cox proportional hazards model. Cows with a PVD score of 2 or 3 were less likely to conceive than cows with a PVD score 0 [score 2 hazard ratio (HR) = 0.74; 95% confidence interval (CI): 0.59-0.94; score 3 HR = 0.65; 95% CI: 0.51-0.84]. Cows with a UE score of 1, 2, 3, or 4 were less likely to conceive than cows with a UE score of 0 (score 1 HR = 0.82; 95% CI: 0.73-0.93; score 2 HR = 0.79; 95% CI: 0.62-1.00; score 3 HR = 0.43; 95% CI: 0.43-0.90; score 4 HR = 0.39; 95% CI: 0.26-0.58). To determine the Se and Sp of PVD or UE score for diagnosis of RTD at the time of PBE, a Bayesian latent class model was fitted on 2,460 individual cow PBE. Flat priors were used for the Se and Sp of UE, whereas informative priors were used for PVD Se (mode = 65%, 5th percentile = 45%) and Sp (mode = 90%, 5th percentile = 80%) and RTD prevalence (mode = 20%, 5th percentile = 10%). Posterior estimates (median and 95% Bayesian probability intervals; BPI) were obtained using 'rjags' (R Studio). The optimal test thresholds (PVD and UE score ≥1) were selected by assessing the effect of different thresholds on test estimates and using a misclassification cost analysis. Based on these, median (95% BPI) Se for PVD and UE score ≥1 were 44% (29-60%) and 67% (33-100%), respectively. Median Sp for PVD and UE score ≥1 were 90% (86-93%) and 91% (86-93%), respectively. Higher scores in both tests were associated with impaired fertility, and UE scoring with a threshold of ≥1 had the highest test Se and Sp estimates although test Se was conditional on days in milk when the PBE occurred.
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Affiliation(s)
- E T Kelly
- School of Veterinary Medicine, University College Dublin (UCD), Belfield, Dublin 4, Ireland D04V1W8.
| | - C G McAloon
- School of Veterinary Medicine, University College Dublin (UCD), Belfield, Dublin 4, Ireland D04V1W8
| | - L O'Grady
- School of Veterinary Medicine, University College Dublin (UCD), Belfield, Dublin 4, Ireland D04V1W8
| | - M Duane
- School of Veterinary Medicine, University College Dublin (UCD), Belfield, Dublin 4, Ireland D04V1W8
| | - J R Somers
- Glanbia Ireland DAC, Kilkenny, Ireland R95 PW86
| | - M E Beltman
- School of Veterinary Medicine, University College Dublin (UCD), Belfield, Dublin 4, Ireland D04V1W8
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Agarwal R, Saxena P, Muthu V, Sehgal IS, Dhooria S, Prasad KT, Aggarwal AN, Chakrabarti A. Evaluation of Simpler Criteria for Diagnosing Allergic Bronchopulmonary Aspergillosis Complicating Asthma. Front Cell Infect Microbiol 2022; 12:861866. [PMID: 35402294 PMCID: PMC8990730 DOI: 10.3389/fcimb.2022.861866] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 03/07/2022] [Indexed: 11/13/2022] Open
Abstract
Background The modified International Society for Human and Animal Mycology (ISHAM) allergic bronchopulmonary aspergillosis (ABPA) working group (AWG) criteria lists up to five components for diagnosing ABPA in asthmatics. Whether eliminating specific components of the existing criteria would have the same diagnostic utility as the original remains unknown. Objective To evaluate the performance of several simplified criteria for diagnosing ABPA. Methods We compared the performance of seven new criteria (after excluding or modifying one or more of the components of the ISHAM-AWG criteria) with the modified ISHAM-AWG criteria in asthmatic subjects using latent class analysis (LCA). We also tested the performance of the newer criteria using accuracy measures against a multidisciplinary team (MDT) diagnosis of ABPA. We considered the diagnostic accuracy of the newer criteria to be acceptable if the correct classification and false-negative rates were >95% and <5%, respectively, on an MDT evaluation. Results We analyzed data from 543 asthmatic subjects (58.8% women; mean age, 36.8 years). Using LCA, the sensitivity of the A.fumigatus-specific IgE-based criteria ranged from 92-99%, while the specificity varied between 92% and 100%. The MDT diagnosed ABPA in 106 (19.5%) subjects. Using MDT as the reference standard, the correct classification and false-negative rates were >95% for three of the seven and <5% for four of the seven newer criteria. Conclusions We found several of the newly developed criteria to perform, like the modified ISHAM-AWG criteria, for diagnosing ABPA complicating asthma. A prospective study in current clinical algorithms is required for validating our observations.
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Affiliation(s)
- Ritesh Agarwal
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Puneet Saxena
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Valliappan Muthu
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Inderpaul Singh Sehgal
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Sahajal Dhooria
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Kuruswamy Thurai Prasad
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Ashutosh Nath Aggarwal
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Arunaloke Chakrabarti
- Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
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Schoneberg C, Böttcher J, Janowetz B, Rostalski A, Kreienbrock L, Campe A. An intercomparison study of ELISAs for the detection of porcine reproductive and respiratory syndrome virus – evaluating six conditionally dependent tests. PLoS One 2022; 17:e0262944. [PMID: 35077518 PMCID: PMC8789123 DOI: 10.1371/journal.pone.0262944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 01/08/2022] [Indexed: 11/18/2022] Open
Abstract
Latent class analysis is a widely used statistical method for evaluating diagnostic tests without any gold standard. It requires the results of at least two tests applied to the same individuals. Based on the resulting response patterns, the method estimates the test accuracy and the unknown disease status for all individuals in the sample. An important assumption is the conditional independence of the tests. If tests with the same biological principle are used, the assumption is not fulfilled, which may lead to biased results. In a recent publication, we developed a method that considers the dependencies in the latent class model and estimates all parameters using frequentist methods. Here, we evaluate the practicability of the method by applying it to the results of six ELISA tests for antibodies against the porcine reproductive and respiratory syndrome (PRRS) virus in pigs that generally follow the same biological principle. First, we present different methods of identifying suitable starting values for the algorithm and apply these to the dataset and a vaccinated subgroup. We present the calculated values of the test accuracies, the estimated proportion of antibody-positive animals and the dependency structure for both datasets. Different starting values led to matching results for the entire dataset. For the vaccinated subgroup, the results were more dependent on the selected starting values. All six ELISA tests are well suited to detect antibodies against PRRS virus, whereas none of the tests had the best values for sensitivity and specificity simultaneously. The results thus show that the method used is able to determine the parameter values of conditionally dependent tests with suitable starting values. The choice of test should be based on the general fit-for-purpose concept and the population under study.
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Affiliation(s)
- Clara Schoneberg
- Department of Biometry, Epidemiology and Information Processing, WHO Collaborating Centre for Research and Training for Health in the Human-Animal-Environment Interface, University for Veterinary Medicine Hannover, Hannover, Germany
- * E-mail:
| | | | | | | | - Lothar Kreienbrock
- Department of Biometry, Epidemiology and Information Processing, WHO Collaborating Centre for Research and Training for Health in the Human-Animal-Environment Interface, University for Veterinary Medicine Hannover, Hannover, Germany
| | - Amely Campe
- Department of Biometry, Epidemiology and Information Processing, WHO Collaborating Centre for Research and Training for Health in the Human-Animal-Environment Interface, University for Veterinary Medicine Hannover, Hannover, Germany
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Arora K, Muthu V, Aggarwal AN, Agarwal R. Can a Test Being Evaluated in a Study Be Itself Used as a Reference Standard? Chest 2021; 159:448. [PMID: 33422220 DOI: 10.1016/j.chest.2020.07.090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 07/29/2020] [Indexed: 11/27/2022] Open
Affiliation(s)
- Kajal Arora
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Valliappan Muthu
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Ashutosh Nath Aggarwal
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Ritesh Agarwal
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
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Clouthier SC, McClure C, Schroeder T, Anderson ED. Bayesian latent class model estimates of diagnostic accuracy for three test methods designed to detect spring viremia of carp virus. Prev Vet Med 2021; 190:105338. [PMID: 33831815 DOI: 10.1016/j.prevetmed.2021.105338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 02/17/2021] [Accepted: 03/21/2021] [Indexed: 10/21/2022]
Abstract
Spring viremia of carp virus (SVCV) causes a systemic hemorrhagic disease that poses a significant risk to wild and cultured fish and is listed as notifiable by the World Organization for Animal Health. Validated molecular diagnostic tools for SVCV are required to accurately describe and analyze the ecology of the virus. Here, the diagnostic specificity (DSp) and sensitivity (DSe) (i.e. accuracy) of three SVCV diagnostic tests - 2 reverse transcription quantitative polymerase chain reaction (RT-qPCR) assays Q1G and Q2N and virus isolation by cell culture (VI) - were evaluated using 2-class latent class models run in maximum likelihood (ML) and Bayesian frameworks. Virus-free or experimentally-infected koi were sorted into three populations with low, moderate or high prevalence levels of SVCV (n = 269 fish in total). Koi kidney tissues were tested using Q2N and Q1G and for the VI assay, pools of kidney, spleen and gill tissues were used. All samples were blinded and analyzed in one laboratory. The ML and Bayesian approaches successfully estimated the diagnostic accuracy of the 3 tests with the exception of 1 ML model. The estimates were consistent across the two frameworks. The DSe estimates were higher for Q1G (>98 %) and Q2N (>96 %) compared to VI (>60 %). The DSp of all three tests varied by 12-15 % (79-91 % for Q1G, 79-94 % for Q2N and 81-97 % for VI) across same-fish samples revealing the potential range in test performance for one sample. The 3 fish populations had distinct SVCV prevalence levels estimated at 0-3 % (low), 70-73 % (moderate) and 95-96 % (high). The Bayesian covariance models revealed minor DSe dependence between Q1G and Q2N. The results suggested that SVCV diagnostic tests Q2N and Q1G are suitable for use as diagnostic assays and are fit for presumptive diagnosis, surveillance, and certification of populations or individuals as SVCV free.
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Affiliation(s)
- Sharon C Clouthier
- Fisheries and Oceans Canada, Freshwater Institute, 501 University Crescent, Winnipeg, Manitoba, R3T 2N6, Canada.
| | - Carol McClure
- AquaEpi Research, RR3, 300 Heartz Road, Charlottetown, Prince Edward Island, C1C 0H8, Canada.
| | - Tamara Schroeder
- Fisheries and Oceans Canada, Freshwater Institute, 501 University Crescent, Winnipeg, Manitoba, R3T 2N6, Canada.
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Schoneberg C, Kreienbrock L, Campe A. An Iterative, Frequentist Approach for Latent Class Analysis to Evaluate Conditionally Dependent Diagnostic Tests. Front Vet Sci 2021; 8:588176. [PMID: 33681320 PMCID: PMC7928357 DOI: 10.3389/fvets.2021.588176] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 01/07/2021] [Indexed: 11/13/2022] Open
Abstract
Latent class analysis is a well-established method in human and veterinary medicine for evaluating the accuracy of diagnostic tests without a gold standard. An important assumption of this procedure is the conditional independence of the tests. If tests with the same biological principle are used, this assumption is no longer met. Therefore, the model has to be adapted so that the dependencies between the tests can be considered. Our approach extends the traditional latent class model with a term for the conditional dependency of the tests. This extension increases the number of parameters to be estimated and leads to negative degrees of freedom of the model, meaning that not enough information is contained in the existing data to obtain a unique estimate. As a result, there is no clear solution. Hence, an iterative algorithm was developed to keep the number of parameters to be estimated small. Given adequate starting values, our approach first estimates the conditional dependencies and then regards the resulting values as fixed to recalculate the test accuracies and the prevalence with the same method used for independent tests. Subsequently, the new values of the test accuracy and prevalence are used to recalculate the terms for the conditional dependencies. These two steps are repeated until the model converges. We simulated five application scenarios based on diagnostic tests used in veterinary medicine. The results suggest that our method and the Bayesian approach produce similar precise results. However, while the presented approach is able to calculate more accurate results than the Bayesian approach if the test accuracies are initially misjudged, the estimates of the Bayesian method are more precise when incorrect dependencies are assumed. This finding shows that our approach is a useful addition to the existing Bayesian methods, while it has the advantage of allowing simpler and more objective estimations.
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Affiliation(s)
- Clara Schoneberg
- Department of Biometry, Epidemiology and Information Processing, WHO Collaborating Centre for Research and Training for Health in the Human-Animal-Environment Interface, University for Veterinary Medicine Hannover, Hannover, Germany
| | - Lothar Kreienbrock
- Department of Biometry, Epidemiology and Information Processing, WHO Collaborating Centre for Research and Training for Health in the Human-Animal-Environment Interface, University for Veterinary Medicine Hannover, Hannover, Germany
| | - Amely Campe
- Department of Biometry, Epidemiology and Information Processing, WHO Collaborating Centre for Research and Training for Health in the Human-Animal-Environment Interface, University for Veterinary Medicine Hannover, Hannover, Germany
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Mortezaee V, Mahdaviani SA, Pourabdollah M, Hassanzad M, Mirenayat MS, Mehrian P, Behnampour N, Yazdani Charati J, Peirovi Z, Sharifynia S, Seyedmousavi S, Hedayati MT. Diagnosis of allergic bronchopulmonary aspergillosis in patients with persistent allergic asthma using three different diagnostic algorithms. Mycoses 2020; 64:272-281. [PMID: 33219548 DOI: 10.1111/myc.13217] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 11/13/2020] [Accepted: 11/13/2020] [Indexed: 01/14/2023]
Abstract
BACKGROUND Allergic bronchopulmonary aspergillosis (ABPA) has been reported in various degrees among patients with persistent allergic asthma (PAA). Currently, there is no gold standard approach for diagnosis of ABPA. OBJECTIVES In the current study, we aimed the evaluation of three different mainly used algorithms as Rosenberg & Patterson (A), ISHAM Working Group (B) and Greenberger (C) for diagnosis of ABPA in 200 patients with underlying PAA. METHODS All patients were evaluated using Aspergillus skin prick test (SPTAf), Aspergillus-specific IgE (sIgEAf) and IgG (sIgGAf), total IgE (tIgE), pulmonary function tests, radiological findings and peripheral blood eosinophil count. The prevalence rate of ABPA in PAA patients was estimated by three diagnostic criteria. We used Latent Class Analysis for the evaluation of different diagnostic parameters in different applied ABPA diagnostic algorithms. RESULTS Aspergillus sensitisation was observed in 30 (15.0%) patients. According to algorithms A, B and C, nine (4.5%), six (3.0%) and 11 (5.5%) of patients were diagnosed with ABPA, respectively. The sensitivity and specificity of criteria B and C were (55.6% and 99.5%) and (100.0% and 98.9%) respectively. sIgEAf and sIgGAf showed the high significant sensitivity. The performance of algorithm A, in terms of sensitivity and specificity, was somewhat better than algorithm B. CONCLUSION Our study demonstrated that the sensitivity of different diagnostic algorithms could change the prevalence rate of ABPA. We also found that all of three criteria resulted an adequate specificity for ABPA diagnosis. A consensus patterns combining elements of all three criteria may warrant a better diagnostic algorithm.
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Affiliation(s)
- Vida Mortezaee
- Department of Medical Mycology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
| | - Seyed Alireza Mahdaviani
- Paediatric Respiratory Diseases Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shaheed Beheshti University of Medical Sciences, Tehran, Iran
| | - Mihan Pourabdollah
- Paediatric Respiratory Diseases Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shaheed Beheshti University of Medical Sciences, Tehran, Iran
| | - Maryam Hassanzad
- Paediatric Respiratory Diseases Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shaheed Beheshti University of Medical Sciences, Tehran, Iran
| | - Maryam Sadat Mirenayat
- Lung Transplantation Research Center (LTRC), National Research Institute of Tuberculosis and Lung Diseases (NIRTLD), Shaheed Beheshti University of Medical Sciences, Tehran, Iran
| | - Payam Mehrian
- Chronic Respiratory Diseases Research Center (CRDRC), National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shaheed Beheshti University of Medical Sciences, Tehran, Iran
| | - Naser Behnampour
- Department of Biostatistics, Faculty of Health, Golestan University of Medical Sciences, Gorgan, Iran
| | - Jamshid Yazdani Charati
- Department of Biostatistics, Faculty of Health, Mazandaran University of Medical Sciences, Sari, Iran
| | - Zahra Peirovi
- Chronic Respiratory Diseases Research Center (CRDRC), National Research Institute of Tuberculosis and Lung Diseases (NRITLD), Shaheed Beheshti University of Medical Sciences, Tehran, Iran
| | - Somayeh Sharifynia
- Clinical Tuberculosis and Epidemiology Research Center, NRITLD, Beheshti University of Medical Sciences, Tehran, Iran
| | - Seyedmojtaba Seyedmousavi
- Microbiology Service, Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, MD, USA.,Invasive Fungi Research Center, Communicable Diseases Institute, Mazandaran University of Medical Sciences, Sari, Iran
| | - Mohammad T Hedayati
- Department of Medical Mycology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran.,Invasive Fungi Research Center, Communicable Diseases Institute, Mazandaran University of Medical Sciences, Sari, Iran
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8
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Saxena P, Choudhary H, Muthu V, Sehgal IS, Dhooria S, Prasad KT, Garg M, Saikia B, Aggarwal AN, Chakrabarti A, Agarwal R. Which Are the Optimal Criteria for the Diagnosis of Allergic Bronchopulmonary Aspergillosis? A Latent Class Analysis. THE JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY-IN PRACTICE 2020; 9:328-335.e1. [PMID: 32890756 DOI: 10.1016/j.jaip.2020.08.043] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 07/29/2020] [Accepted: 08/18/2020] [Indexed: 12/12/2022]
Abstract
BACKGROUND The ideal criteria for diagnosing allergic bronchopulmonary aspergillosis (ABPA) remain unknown because of the lack of a criterion standard. Latent class analysis using a probabilistic modeling technique can circumvent the need for a reference standard. OBJECTIVE To compare the diagnostic performance of various criteria used for evaluating ABPA. METHODS We prospectively enrolled consecutive cases of bronchial asthma and performed a series of investigations used for the diagnosis of ABPA. We used latent class analysis to analyze the performance of various existing and novel diagnostic criteria. RESULTS Of the 543 subjects (mean age, 37 years; 319 women), 338 (62.2%) and 205 (37.8%) were labeled as "mild-to-moderate" and "severe" asthma cases, respectively. The subjects with severe asthma had a longer duration of asthma and a higher number of exacerbations in the previous year. The prevalence of Aspergillus fumigatus sensitization was 41% and 30%, using the A fumigatus-specific IgE and skin test, respectively. The prevalence of ABPA was 16%, using both the Rosenberg-Patterson and the International Society for Human and Animal Mycology (ISHAM)-ABPA Working Group criteria. The ISHAM criteria were slightly more sensitive (89% vs 81%) and specific (99% vs 98%) than the Patterson criteria. We obtained optimal diagnostic performance by altering the existing ISHAM criteria (serum total IgE >500 international units/mL, excluding the skin test, and using computed tomography of thorax instead of chest radiograph). CONCLUSIONS The ISHAM-ABPA Working Group criteria were only marginally better than the Patterson criteria in diagnosing ABPA among patients with asthma younger than 66 years. The diagnostic performance however improved by modifying the prevailing ISHAM criteria, but with increased cost.
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Affiliation(s)
- Puneet Saxena
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Hansraj Choudhary
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India; Department of Medical Microbiology, PGIMER, Chandigarh, India
| | - Valliappan Muthu
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Inderpaul Singh Sehgal
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Sahajal Dhooria
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Kuruswamy Thurai Prasad
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Mandeep Garg
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India; Department of Radiodiagnosis and Imaging, PGIMER, Chandigarh, India
| | - Biman Saikia
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India; Department of Immunopathology, PGIMER, Chandigarh, India
| | - Ashutosh Nath Aggarwal
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
| | - Arunaloke Chakrabarti
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India; Department of Medical Microbiology, PGIMER, Chandigarh, India
| | - Ritesh Agarwal
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India.
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Walser M, Bosshard P. Development and evaluation of a pan‐dermatophyte polymerase chain reaction with species‐level identification using sloppy molecular beacon probes. Br J Dermatol 2019; 180:1489-1497. [DOI: 10.1111/bjd.17512] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/03/2018] [Indexed: 11/29/2022]
Affiliation(s)
- M. Walser
- Institute of Molecular Life Sciences University of Zurich Winterthurerstr. 190 CH‐8057 Zurich Switzerland
| | - P.P. Bosshard
- Department of Dermatology University Hospital Zurich Gloriastrasse 31 CH‐8091 Zurich Switzerland
- Faculty of Medicine University of Zurich Gloriastrasse 31 CH‐8091 Zurich Switzerland
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Mourand G, Jouy E, Chauvin C, Le Devendec L, Paboeuf F, Kempf I. Dissemination of the mcr-1 colistin resistance gene among pigs: An experimental study. Vet Microbiol 2018; 221:122-128. [PMID: 29981697 DOI: 10.1016/j.vetmic.2018.06.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 06/01/2018] [Accepted: 06/07/2018] [Indexed: 10/14/2022]
Abstract
Colistin resistance in Enterobacteriaceae is a public health problem. The present study was designed to evaluate the dissemination of a colistin-resistant Escherichia coli strain and its resistance gene, mcr-1, between orally inoculated pigs and their contacts. A non-inoculated control group, one low-dose and one high-dose group-both including two pens of two inoculated and three contact pigs-were raised in separate rooms. After inoculation of a colistin- and rifampicin-resistant E. coli suspension (2.5 × 105 CFU/pig for the low-dose group and 2.5 × 108 CFU/pig for the high-dose group), feces from inoculated and non-inoculated contact pigs were collected and inoculated on colistin- and rifampicin-supplemented media directly or after enrichment in rifampicin-supplemented media, then the isolates were characterized. PCR was used to detect the mcr-1 gene in lysates from feces cultivated in colistin-supplemented broth and DNA prepared from feces. Results showed that the low-dose inoculum was probably insufficient to obtain durable colonization, but could lead to the temporary presence of mcr-1-positive E. coli strains. The high-dose inoculum resulted in durable colonization of both inoculated and contact animals. In all groups, the mcr-1 gene was also detected in rifampicin-susceptible strains, suggesting its transfer to several commensal strains. A comparison of detection methods showed that more positive samples were obtained with cultures in rifampicin-supplemented media and suggests that current methods to evaluate the prevalence of colistin resistance in fecal samples suffer from poor sensitivity.
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Affiliation(s)
- Gwenaelle Mourand
- ANSES, Laboratoire de Ploufragan-Plouzané, Ploufragan, France; Université Bretagne Loire, France
| | - Eric Jouy
- ANSES, Laboratoire de Ploufragan-Plouzané, Ploufragan, France; Université Bretagne Loire, France
| | - Claire Chauvin
- ANSES, Laboratoire de Ploufragan-Plouzané, Ploufragan, France; Université Bretagne Loire, France
| | - Laetitia Le Devendec
- ANSES, Laboratoire de Ploufragan-Plouzané, Ploufragan, France; Université Bretagne Loire, France
| | - Frédéric Paboeuf
- ANSES, Laboratoire de Ploufragan-Plouzané, Ploufragan, France; Université Bretagne Loire, France
| | - Isabelle Kempf
- ANSES, Laboratoire de Ploufragan-Plouzané, Ploufragan, France; Université Bretagne Loire, France.
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Awah-Ndukum J, Mouiche MMM, Bayang HN, Ngwa VN, Assana E, Feussom KJM, Manchang TK, Zoli PA. Seroprevalence and Associated Risk Factors of Brucellosis among Indigenous Cattle in the Adamawa and North Regions of Cameroon. Vet Med Int 2018; 2018:3468596. [PMID: 29535853 PMCID: PMC5817279 DOI: 10.1155/2018/3468596] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 11/15/2017] [Accepted: 12/03/2017] [Indexed: 11/25/2022] Open
Abstract
A cross-sectional seroprevalence study was conducted on cattle in the North and Adamawa Regions of Cameroon to investigate the status of bovine brucellosis and identify potential risk factors. The diagnosis was carried out using the Rose Bengal Plate test (RBPT) and indirect ELISA (i-ELISA), while questionnaires were used to evaluate risk factors for bovine brucellosis in cattle. The Bayesian approach was used to evaluate the diagnostic tests' sensitivity and specificity. The overall individual level (n = 1031) and herd level (n = 82) seroprevalence were 5.4% (0.4-10.5) and 25.6% (16.2-35.0), respectively. Bayesian analysis revealed sensitivity of 58.3% (26.4-92.7) and 89.6% (80.4-99.4) and specificity of 92.1% (88.7-95.2) and 95.7% (91.1-99.7) for RBPT and i-ELISA, respectively. Management related factors such as region, locality, herd size, and knowledge of brucellosis and animal related factors such as sex and age were significantly associated with seropositivity of brucellosis. Zoonotic brucellosis is a neglected disease in Cameroon. The study highlights the need for control measures and the need to raise public awareness of the zoonotic occurrence and transmission of bovine brucellosis in the country. An integrated disease control strategy mimicking the one health approach involving medical personnel, veterinarians, related stakeholders, and affected communities cannot be overemphasized.
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Affiliation(s)
- J. Awah-Ndukum
- School of Veterinary Medicine and Sciences, University of Ngaoundéré, Ngaoundéré, Cameroon
| | - M. M. M. Mouiche
- School of Veterinary Medicine and Sciences, University of Ngaoundéré, Ngaoundéré, Cameroon
| | - H. N. Bayang
- Institute of Agricultural Research for Development, Veterinary Research Laboratory, Wakwa Regional Center, Ngaoundéré, Cameroon
| | - V. Ngu Ngwa
- School of Veterinary Medicine and Sciences, University of Ngaoundéré, Ngaoundéré, Cameroon
| | - E. Assana
- School of Veterinary Medicine and Sciences, University of Ngaoundéré, Ngaoundéré, Cameroon
| | - K. J. M. Feussom
- Epidemio-Surveillance Service, Ministry of Livestock, Fisheries, Animal Industries, Yaoundé, Cameroon
| | - T. K. Manchang
- Institute of Agricultural Research for Development, Veterinary Research Laboratory, Wakwa Regional Center, Ngaoundéré, Cameroon
| | - P. A. Zoli
- School of Veterinary Medicine and Sciences, University of Ngaoundéré, Ngaoundéré, Cameroon
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Diagnostic accuracy of enzyme-linked immunosorbent assay (ELISA) and immunoblot (IB) for the detection of antibodies against Neospora caninum in milk from dairy cows. Epidemiol Infect 2017; 146:577-583. [PMID: 29271333 DOI: 10.1017/s0950268817002916] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The aim of the study was to estimate the sensitivity and specificity of enzyme-linked immunosorbent assay (ELISA) and immunoblot (IB) for detecting antibodies of Neospora caninum in dairy cows, in the absence of a gold standard. The study complies with STRADAS-paratuberculosis guidelines for reporting the accuracy of the test. We tried to apply Bayesian models that do not require conditional independence of the tests under evaluation, but as convergence problems appeared, we used Bayesian methodology, that does not assume conditional dependence of the tests. Informative prior probability distributions were constructed, based on scientific inputs regarding sensitivity and specificity of the IB test and the prevalence of disease in the studied populations. IB sensitivity and specificity were estimated to be 98.8% and 91.3%, respectively, while the respective estimates for ELISA were 60% and 96.7%. A sensitivity analysis, where modified prior probability distributions concerning IB diagnostic accuracy applied, showed a limited effect in posterior assessments. We concluded that ELISA can be used to screen the bulk milk and secondly, IB can be used whenever needed.
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Clouthier SC, McClure C, Schroeder T, Desai M, Hawley L, Khatkar S, Lindsay M, Lowe G, Richard J, Anderson ED. Diagnostic validation of three test methods for detection of cyprinid herpesvirus 3 (CyHV-3). DISEASES OF AQUATIC ORGANISMS 2017; 123:101-122. [PMID: 28262633 DOI: 10.3354/dao03093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Cyprinid herpesvirus 3 (CyHV-3) is the aetiological agent of koi herpesvirus disease in koi and common carp. The disease is notifiable to the World Organisation for Animal Health. Three tests-quantitative polymerase chain reaction (qPCR), conventional PCR (cPCR) and virus isolation by cell culture (VI)-were validated to assess their fitness as diagnostic tools for detection of CyHV-3. Test performance metrics of diagnostic accuracy were sensitivity (DSe) and specificity (DSp). Repeatability and reproducibility were measured to assess diagnostic precision. Estimates of test accuracy, in the absence of a gold standard reference test, were generated using latent class models. Test samples originated from wild common carp naturally exposed to CyHV-3 or domesticated koi either virus free or experimentally infected with the virus. Three laboratories in Canada participated in the precision study. Moderate to high repeatability (81 to 99%) and reproducibility (72 to 97%) were observed for the qPCR and cPCR tests. The lack of agreement observed between some of the PCR test pair results was attributed to cross-contamination of samples with CyHV-3 nucleic acid. Accuracy estimates for the PCR tests were 99% for DSe and 93% for DSp. Poor precision was observed for the VI test (4 to 95%). Accuracy estimates for VI/qPCR were 90% for DSe and 88% for DSp. Collectively, the results show that the CyHV-3 qPCR test is a suitable tool for surveillance, presumptive diagnosis and certification of individuals or populations as CyHV-3 free.
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Affiliation(s)
- Sharon C Clouthier
- Fisheries and Oceans Canada, Freshwater Institute, 501 University Crescent, Winnipeg, Manitoba R3T 2N6, Canada
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Kungu JM, Dione MM, Ejobi F, Harrison LJS, Poole EJ, Pezo D, Grace D. Sero-prevalence of Taenia spp. cysticercosis in rural and urban smallholder pig production settings in Uganda. Acta Trop 2017; 165:110-115. [PMID: 26801882 DOI: 10.1016/j.actatropica.2016.01.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 01/12/2016] [Accepted: 01/15/2016] [Indexed: 11/30/2022]
Abstract
The pork tapeworm, Taenia solium, is prevalent in Uganda although the prevalence has not been determined in all areas of the country. A cross-sectional study, to determine the sero-prevalence of the parasite in pigs kept under rural and urban production settings, was carried out in three Ugandan districts, Masaka, Mukono and Kamuli. Serum samples from 1185 pigs were tested for the presence of T. solium cysticercosis antigen using the HP10 antigen-ELISA (Ag-ELISA) and the ApDia Ag-ELISA assays. Using parallel interpretation of the two tests showed lower levels of observed prevalence of T. solium in rural production settings (10.8%) compared to urban (17.1%). Additionally, Maximum Likelihood Estimation for evaluating assays in the absence of a gold standard, using TAGS on the R platform, estimated the true sero-prevalence to be lower in rural production setting, 0.0% [0.0-3.2%; 95% confidence interval (CI)] than in urban production setting, 12.3% (4.2-77.5% CI). When the sensitivity/specificity (Se/Sp) of the assays were estimated, assuming conditional independence of the tests, HP10 Ag-ELISA was more sensitive and specific [(Se=53.9%; 10.1-100% CI), (Sp=97.0%; 95.9-100% CI)] than the ApDia assay [(Se=20.2%; 1.5-47.7% CI), (Sp=92.2%; 90.5-93.9% CI)]. Subject to parasitological verification, these results indicate there may be a need to implement appropriate control measures for T. solium in the study areas.
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Affiliation(s)
- Joseph M Kungu
- National Livestock Research Resources Institute, P. O. Box 96, Tororo, Uganda; College of Veterinary Medicine and Biosecurity, Makerere University, P. O. Box 7062, Kampala, Uganda; International Livestock Research Institute, P.O. Box 24384, Kampala, Uganda.
| | - Michel M Dione
- International Livestock Research Institute, P.O. Box 24384, Kampala, Uganda.
| | - Francis Ejobi
- College of Veterinary Medicine and Biosecurity, Makerere University, P. O. Box 7062, Kampala, Uganda.
| | - Leslie J S Harrison
- University of Edinburgh, Royal (Dick) School of Veterinary Science, Easter Bush Veterinary Centre, Easter Bush, Roslin, Midlothian, Scotland EH259RG, UK.
| | - E Jane Poole
- International Livestock Research Institute, P.O. Box 30709, Nairobi, Kenya.
| | - Danilo Pezo
- International Livestock Research Institute, P.O. Box 24384, Kampala, Uganda.
| | - Delia Grace
- International Livestock Research Institute, P.O. Box 30709, Nairobi, Kenya.
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Lardeux F, Aliaga C, Depickère S. Bias due to methods of parasite detection when estimating prevalence of infection of Triatoma infestans by Trypanosoma cruzi. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2016; 41:285-291. [PMID: 27860015 DOI: 10.1111/jvec.12224] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 08/08/2016] [Indexed: 06/06/2023]
Abstract
The study aimed to quantify the bias from parasite detection methods in the estimation of the prevalence of infection of Triatoma infestans by Trypanosoma cruzi, the agent of Chagas disease. Three common protocols that detect T. cruzi in a sample of 640 wild-caught T. infestans were compared: (1) the microscopic observation of insect fecal droplets, (2) a PCR protocol targeting mini-exon genes of T. cruzi (MeM-PCR), and (3) a PCR protocol targeting a satellite repeated unit of the parasite. Agreement among protocols was computed using Krippendorff Kα. The sensitivity (Se) and specificity (Sp) of each protocol was estimated using latent class models. The PCR protocols were more sensitive (Se > 0.97) than microscopy (Se = 0.53) giving a prevalence of infection of 17-18%, twice as high as microscopy. Microscopy may not be as specific as PCR if Trypanosomatid-like organisms make up a high proportion of the sample. For small T. infestans, microscopy is not efficient, giving a prevalence of 1.5% when PCR techniques gave 10.7%. The PCR techniques were in agreement (Kα = 0.94) but not with microscopy (Kα never significant with both PCR techniques). Among the PCR protocols, the MeM-PCR was the most efficient (Se=1; Sp=1).
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Affiliation(s)
- Frédéric Lardeux
- Institut de Recherche pour le Développement (IRD), C.P. 9214, La Paz, Bolivia
- Institut de Recherche pour le Développement (IRD), UMR MIVEGEC, 911 avenue Agropolis, BP 64501, 34394 Montpellier Cedex, France
| | - Claudia Aliaga
- Institut de Recherche pour le Développement (IRD), C.P. 9214, La Paz, Bolivia
- Instituto Nacional de Laboratorios de Salud (INLASA), calle Rafaël Zubieta, La Paz, Bolivia
| | - Stéphanie Depickère
- Institut de Recherche pour le Développement (IRD), C.P. 9214, La Paz, Bolivia
- Instituto Nacional de Laboratorios de Salud (INLASA), calle Rafaël Zubieta, La Paz, Bolivia
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16
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Ahasan MS, Rahman MS, Rahman AKMA, Berkvens D. Bovine and Caprine Brucellosis in Bangladesh: Bayesian evaluation of four serological tests, true prevalence, and associated risk factors in household animals. Trop Anim Health Prod 2016; 49:1-11. [PMID: 27628065 DOI: 10.1007/s11250-016-1151-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 09/07/2016] [Indexed: 11/26/2022]
Abstract
A cross-sectional study was carried out to estimate the true prevalence of Brucella spp. and identify allied risk factors/indicators associated with brucellosis in the Dinajpur and Mymensingh districts of Bangladesh. A total 320 stratified random blood samples were collected and tested in parallel for Brucella antibodies using Rose Bengal (RBT), slow agglutination (SAT), and indirect and competitive ELISA. In addition, a structured questionnaire was administered to each household herd owner to gather information regarding potential risk factors. Both univariate and multivariate logistic regression analyses were used to identify potential risk factors or indicators at animal level. A Bayesian approach was used to estimate the true prevalence of brucellosis along with the test performances (Se and Sp). The estimated animal level true prevalence in cattle was 9.70 % (95 % CPI 5.0-16 %) and in goat 6.3 % (95 % CPI 2.8-11.0 %). The highest sensitivity was achieved by SAT ranges from 69.6 to 78.9 %, and iELISA was found to be more specific (97.4 to 98.8 %) in comparison with other tests. On the other hand, a significant level of (P < 0.05) Brucella seropositivity was found in cattle that breed naturally compared with those that undergo artificial insemination. In goats, exotic breeds were significantly associated (P < 0.05) with Brucella seroprevalence compared with indigenous breeds. Goats with a previous records of abortion and/or retained placenta were also found to have significant levels (P < 0.05). Cows with previous abortion records showed higher odds (18 times) of being seropositive. None of the evaluated tests can be recommended to apply alone for the diagnosis of bovine and caprine brucellosis.
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Affiliation(s)
- Md Shamim Ahasan
- Unit of Biostatistics and Epidemiology, Department of Biomedical Sciences, Institute of Tropical Medicine (ITM), Nationalestraat 155, B-2000, Antwerp, Belgium.
- Department of Medicine, Surgery and Obstetrics, Hajee Mohammad Danesh Science and Technology University, Dinajpur, 5200, Bangladesh.
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia.
| | - Md Siddiqur Rahman
- Department of Medicine, Bangladesh Agricultural University, Mymensingh, 2202, Bangladesh
| | - A K M Anisur Rahman
- Department of Medicine, Bangladesh Agricultural University, Mymensingh, 2202, Bangladesh
| | - Dirk Berkvens
- Unit of Biostatistics and Epidemiology, Department of Biomedical Sciences, Institute of Tropical Medicine (ITM), Nationalestraat 155, B-2000, Antwerp, Belgium
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17
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Bayesian Estimation of Sensitivity and Specificity of Rose Bengal, Complement Fixation, and Indirect ELISA Tests for the Diagnosis of Bovine Brucellosis in Ethiopia. Vet Med Int 2016; 2016:8032753. [PMID: 27595036 PMCID: PMC4993953 DOI: 10.1155/2016/8032753] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 06/20/2016] [Accepted: 06/30/2016] [Indexed: 11/17/2022] Open
Abstract
Test evaluation in the absence of a gold standard test was conducted for the diagnosis and screening of bovine brucellosis using three commercially available tests including RBPT, CFT, and I-ELISA in National Animal Health Diagnostic and Investigation Center (NAHDIC) Ethiopia. A total of 278 sera samples from five dairy herds were collected and tested. Each serum sample was subjected to the three tests and the results obtained were recorded and the test outcomes were cross-classified to estimate the sensitivity and specificity of the tests using Bayesian model. Prior information generated on the sensitivity and specificity of bovine brucellosis from published data was used in the model. The three test-one population Bayesian model was modified and applied using WinBug software with the assumption that the dairy herds have similar management system and unknown disease status. The Bayesian posterior estimate for sensitivity was 89.6 (95% PI: 79.9-95.8), 96.8 (95% PI: 92.3-99.1), and 94 (95% PI: 87.8-97.5) and for specificity was 84.5 (95% PI: 68-94.98), 96.3 (95% PI: 91.7-98.8), and 88.5 (95% PI: 81-93.8) for RBT, I-ELISA, and CFT, respectively. In this study I-ELISA was found with the best sensitivity and specificity estimates 96.8 (95% PI: 92.3-99.1) and 96.3 (95% PI: 91.7-98.8), compared to both CFT and RBPT.
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18
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Dewell GA, Phillips PE, Dohlman TM, Harmon KM, Gauger PC. Validation of a gauze sponge sampling methodology to detect Tritrichomonas foetus by real-time PCR. J Vet Diagn Invest 2016; 28:595-8. [PMID: 27400955 DOI: 10.1177/1040638716653637] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Bovine trichomoniasis is a concern for the cattle industry. Advances in testing systems have increased the ability to detect the disease in bulls. However, the greatest limitation is proper collection of an adequate sample. The low repeatability observed with most sample collection techniques can cause false-negative results. The aim of our study was to validate a sample collection technique that increases diagnostic sensitivity and is easier and safer to collect than preputial scraping. Commercial bulls (n = 111) of unknown infection status were sampled for detection of Tritrichomonas foetus using 2 different collection methods: 1) preputial scraping with a dry insemination pipette and 2) penile sponging with a 16-ply gauze sponge. Preputial scraping samples were collected by vigorously scraping preputial and penile mucosa using a rigid insemination pipette while applying negative pressure with a syringe. Penile sponge samples were obtained by swabbing the penile and preputial mucosa with a gauze sponge during full extension of the penis. All samples were processed using a commercial medium and submitted under similar conditions for PCR testing. Positive PCR results were detected in 37 of 111 (33%) bulls using the preputial scraping technique; however, 39 of 111 (35%) were positive using the penile sponging technique. The Newton-Raphson algorithm predicted that the sensitivity of the preputial scraping method was 0.919 (95% CI: 0.689-0.983) and the sensitivity of the penile sponging was 0.949 (95% CI: 0.818-0.987). These data indicate that the penile sponging technique is a reliable alternative to the preputial scraping method.
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Affiliation(s)
- Grant A Dewell
- Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, IA
| | - Patrick E Phillips
- Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, IA
| | - Tyler M Dohlman
- Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, IA
| | - Karen M Harmon
- Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, IA
| | - Phil C Gauger
- Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, IA
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19
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Latent class regression models for simultaneously estimating test accuracy, true prevalence and risk factors for Brucella abortus. Epidemiol Infect 2016; 144:1845-56. [DOI: 10.1017/s0950268816000157] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
SUMMARYIn 2003/2004 a field trial was conducted in Northern Ireland to assess the diagnostic accuracy of six serological tests for bovine brucellosis caused by Brucella abortus. Whereas between-test comparisons have been used to calculate test performances so far, the present study used a latent class approach to estimate diagnostic test accuracy parameters in the absence of a gold standard for these six tests simultaneously and to estimate the true prevalence, while accounting for clustering in the study population and risk factors for true prevalence. Results obtained in this study with regard to prevalence, sensitivity and specificity were largely in accordance with previous findings. Screening tests (SAT and EDTA) appeared to be the most sensitive; however, at low prevalences the EDTA and CFT showed the highest positive predictive values of all investigated tests. The specificities and negative predictive values of all diagnostic tests were found to be very high. Differences of prevalence between three groups of the study population with different risk of exposure could be attributed to the mode of sampling indicating that a more risk-based sampling will result in a higher prevalence than a cross-sectional sampling mode. Age, dairy status and history of abortion were shown to influence the prediction of the latent true infection status.
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Gustafson L, Remmenga M, Sandoval Del Valle O, Ibarra R, Antognoli M, Gallardo A, Rosenfeld C, Doddis J, Enriquez Sais R, Bell E, Lara Fica M. Area contact networks and the spatio-temporal spread of infectious salmon anemia virus (ISAV) in Chile. Prev Vet Med 2016; 125:135-46. [PMID: 26774449 DOI: 10.1016/j.prevetmed.2016.01.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 12/21/2015] [Accepted: 01/03/2016] [Indexed: 10/22/2022]
Abstract
Area management, the coordination of production and biosecurity practices across neighboring farms, is an important disease control strategy in aquaculture. Area management in aquaculture escalated in prominence in response to outbreaks of infectious salmon anemia (ISA) internationally. Successes in disease control have been attributed to the separation achieved through area-level synchronized stocking, fallowing, movement restrictions, and fomite or pest control. Area management, however, is costly; often demanding extra biosecurity, lengthy or inconveniently timed fallows, and localization of equipment, personnel, and services. Yet, this higher-order organizational structure has received limited epidemiologic attention. Chile's National Fisheries and Aquaculture Service instigated area management practices in response to the 2007 emergence of ISA virus (ISAV). Longitudinal data simultaneously collected allowed retrospective evaluation of the impact of component tenets on virus control. Spatiotemporal analyses identified hydrographic linkages, shared ports, and fish transfers from areas with recent occurrence of ISAV as the strongest predictors of virus spread between areas, though specifics varied by ISAV type (here categorized as HPR0 for the non-virulent genotypes, and HPRv otherwise). Hydrographic linkages were most predictive in the period before implementation of enhanced biosecurity and fallowing regulations, suggesting that viral load can impact spread dynamics. HPR0 arose late in the study period, so few HPRv events were available by which to explore the hypothesis of HPR0 as progenitor of outbreaks. However, spatiotemporal patterns in HPRv occurrence were predictive of subsequent patterns in HPR0 detection, suggesting a parallel, or dependent, means of spread. Better data precision, breadth and consistency, common challenges for retrospective studies, could improve model fit; and, for HPR0, specification of diagnostic test accuracy would improve interpretation.
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Affiliation(s)
- L Gustafson
- USDA APHIS VS Centers for Epidemiology and Animal Health, Surveillance Design and Analysis, 2150 Centre Ave, Fort Collins, CO 80526-8117, United States.
| | - M Remmenga
- USDA APHIS VS Centers for Epidemiology and Animal Health, Surveillance Design and Analysis, 2150 Centre Ave, Fort Collins, CO 80526-8117, United States
| | - O Sandoval Del Valle
- Sernapesca, Chile's National Fisheries and Aquaculture Service, Victoria 2832, Valparaiso, Chile
| | - R Ibarra
- SalmonChile, Department of Fish Health, Instituto Tecnologico del Salmon, Av. Juan Soler Manfredini 41, OF 1802 Puerto Montt, Chile
| | - M Antognoli
- USDA APHIS VS Centers for Epidemiology and Animal Health, Surveillance Design and Analysis, 2150 Centre Ave, Fort Collins, CO 80526-8117, United States
| | - A Gallardo
- Sernapesca, Chile's National Fisheries and Aquaculture Service, Victoria 2832, Valparaiso, Chile
| | - C Rosenfeld
- Instituto de Medicina Preventiva Veterinaria Facultad de Ciencias Veterinarias Universidad Austral de Chile Campus Isla Teja s/n, Valdivia, Chile
| | - J Doddis
- Instituto de Medicina Preventiva Veterinaria Facultad de Ciencias Veterinarias Universidad Austral de Chile Campus Isla Teja s/n, Valdivia, Chile
| | - R Enriquez Sais
- Lab de Biotecnologia y Patologia Acuatica Facultad de Ciencias Veterinarias Universidad Austral de Chile Campus Isla Teja s/n, Valdivia, Chile
| | - E Bell
- Colorado Department of Public Health and Environment, 4300 Cherry Creek Drive South, Denver, CO 80246, United States
| | - M Lara Fica
- Sernapesca, Chile's National Fisheries and Aquaculture Service, Victoria 2832, Valparaiso, Chile
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Benfer KA, Weir KA, Bell KL, Ware RS, Davies PSW, Boyd RN. Validity and reproducibility of measures of oropharyngeal dysphagia in preschool children with cerebral palsy. Dev Med Child Neurol 2015; 57:358-65. [PMID: 25382696 DOI: 10.1111/dmcn.12616] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/06/2014] [Indexed: 11/30/2022]
Abstract
AIM The aim of the study was to determine the best measure to discriminate between those with oropharyngeal dysphagia (OPD) and those without OPD, among young children with cerebral palsy (CP). METHOD We carried out a cross-sectional population-based study involving 130 children with CP aged between 18 months and 36 months (mean 27.4mo; 81 males, 49 females) classified according to the Gross Motor Function Classification Scale (GMFCS) as level I (n=57), II (n=15), III (n=23), IV (n=12), or V (n=23). Forty children with CP (mean 28.5mo; 21 males,19 females, eight for each GMFCS level) were included in the reproducibility sub-study, and 40 children with typical development (mean 26.2mo; 18 males, 22 females) were included in the validity sub-study. OPD was assessed using the Dysphagia Disorders Survey (DDS), Pre-Speech Assessment Scale (PSAS), and Schedule for Oral Motor Assessment (SOMA). We analysed reproducibility using inter- and intrarater agreement (percentage) and reliability (kappa values and intraclass correlation coefficients). Construct validity was assessed as concordance between measures (SOMA, DDS, and PSAS). In the absence of a criterion standard measure for OPD, prevalence was estimated using latent class variable analysis. Data from the children with typical development were used to propose modified OPD cut-points for discriminative validity. RESULTS All measures had strong agreement (>85%) for inter- and intrarater reliability. The SOMA had the best specificity (100.0%), but lacked sensitivity (53.0%), whereas the DDS and PSAS had high sensitivity (each 100.0%) but lacked specificity (47.1% and 70.6% respectively). OPD prevalence when calculated using the web-based estimation was 65.4%, which was similar to the estimate from the modified cut-points. INTERPRETATION Using the sample of children with typical development and modified cut-points, OPD prevalence was lower than estimates with standard scoring. We propose using these modified cut-points when administering the DDS, PSAS or SOMA in young children with CP.
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Affiliation(s)
- Katherine A Benfer
- Queensland Cerebral Palsy and Rehabilitation Research Centre, The University of Queensland, Brisbane, Qld, Australia
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Bayesian versus frequentist methods for estimating true prevalence of disease and diagnostic test performance. Vet J 2014; 202:204-7. [DOI: 10.1016/j.tvjl.2014.08.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Revised: 08/02/2014] [Accepted: 08/04/2014] [Indexed: 11/18/2022]
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Ramilo A, Villalba A, Abollo E. Species-specific oligonucleotide probe for detection of Bonamia exitiosa (Haplosporidia) using in situ hybridisation assay. DISEASES OF AQUATIC ORGANISMS 2014; 110:81-91. [PMID: 25060500 DOI: 10.3354/dao02646] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Bonamiosis is a disease affecting various oyster species and causing oyster mass mortalities worldwide. The protozoans Bonamia exitiosa and B. ostreae (Haplosporidia) are included in the list of notifiable diseases of the World Organisation for Animal Health as the causative agents of this disease. Although the geographic range of both species was considered different for years, both species are now known to co-occur in some European areas affecting the same host, Ostrea edulis, which strengthens the need of species-specific methods to unequivocally identify the species of Bonamia. An oligonucleotide probe for specific detection of B. exitiosa (BEX_ITS) was designed to be used in in situ hybridisation (ISH) assays. ISH assay with BEX_ITS probe showed species-specificity and more sensitivity than traditional histology to visualise the parasite inside host tissue. ISH assay showed that the oyster gonad was the area where the parasite was most frequently located, and was the exclusive organ of infection in some oysters. A recommendation arising from the study is that more than 1 organ (including gonad and gills) should be used for PCR-based diagnosis of B. exitiosa, to maximise the sensitivity.
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Affiliation(s)
- Andrea Ramilo
- Centro de Investigacións Mariñas, Consellería do Medio Rural e do Mar, Xunta de Galicia, 36620 Vilanova de Arousa, Spain
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Collins J, Huynh M. Estimation of diagnostic test accuracy without full verification: a review of latent class methods. Stat Med 2014; 33:4141-69. [PMID: 24910172 DOI: 10.1002/sim.6218] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 05/02/2014] [Accepted: 05/05/2014] [Indexed: 11/09/2022]
Abstract
The performance of a diagnostic test is best evaluated against a reference test that is without error. For many diseases, this is not possible, and an imperfect reference test must be used. However, diagnostic accuracy estimates may be biased if inaccurately verified status is used as the truth. Statistical models have been developed to handle this situation by treating disease as a latent variable. In this paper, we conduct a systematized review of statistical methods using latent class models for estimating test accuracy and disease prevalence in the absence of complete verification.
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Affiliation(s)
- John Collins
- Rehabilitation Medicine Department, National Institutes of Health, Bethesda MD 20892, U.S.A
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de Boer MW, LeBlanc SJ, Dubuc J, Meier S, Heuwieser W, Arlt S, Gilbert RO, McDougall S. Invited review: Systematic review of diagnostic tests for reproductive-tract infection and inflammation in dairy cows. J Dairy Sci 2014; 97:3983-99. [PMID: 24835959 DOI: 10.3168/jds.2013-7450] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Accepted: 03/29/2014] [Indexed: 11/19/2022]
Abstract
The objective of this study was to conduct a systematic and critical appraisal of the quality of previous publications and describe diagnostic methods, diagnostic criteria and definitions, repeatability, and agreement among methods for diagnosis of vaginitis, cervicitis, endometritis, salpingitis, and oophoritis in dairy cows. Publications (n=1,600) that included the words "dairy," "cows," and at least one disease of interest were located with online search engines. In total, 51 papers were selected for comprehensive review by pairs of the authors. Only 61% (n=31) of the 51 reviewed papers provided a definition or citation for the disease or diagnostic methods studied, and only 49% (n=25) of the papers provided the data or a citation to support the test cut point used for diagnosing disease. Furthermore, a large proportion of the papers did not provide sufficient detail to allow critical assessment of the quality of design or reporting. Of 11 described diagnostic methods, only one complete methodology, i.e., vaginoscopy, was assessed for both within- and between-operator repeatability (κ=0.55-0.60 and 0.44, respectively). In the absence of a gold standard, comparisons between different tests have been undertaken. Agreement between the various diagnostic methods is at a low level. These discrepancies may indicate that these diagnostic methods assess different aspects of reproductive health and underline the importance of tying diagnostic criteria to objective measures of reproductive performance. Those studies that used a reproductive outcome to select cut points and tests have the greatest clinical utility. This approach has demonstrated, for example, that presence of (muco)purulent discharge in the vagina and an increased proportion of leukocytes in cytological preparations following uterine lavage or cytobrush sampling are associated with poorer reproductive outcomes. The lack of validated, consistent definitions and outcome variables makes comparisons of the different tests difficult. The quality of design and reporting in future publications could be improved by using checklists as a guideline. Further high-quality research based on published standards to improve study design and reporting should improve cow-side diagnostic tests. Specifically, more data on intra- and interobserver agreement are needed to evaluate test variability. Also, more studies are necessary to determine optimal cut points and time postpartum of examination.
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Affiliation(s)
- M W de Boer
- Cognosco, Anexa Animal Health, Morrinsville 3300, New Zealand; Epicentre, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North 4442, New Zealand.
| | - S J LeBlanc
- Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - J Dubuc
- Département de Sciences Cliniques, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec J2S 7C6, Canada
| | - S Meier
- DairyNZ Limited, Hamilton 3240, New Zealand
| | - W Heuwieser
- Clinic for Animal Reproduction, Faculty of Veterinary Medicine, Freie Universität Berlin, 14163 Berlin, Germany
| | - S Arlt
- Clinic for Animal Reproduction, Faculty of Veterinary Medicine, Freie Universität Berlin, 14163 Berlin, Germany
| | - R O Gilbert
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853
| | - S McDougall
- Cognosco, Anexa Animal Health, Morrinsville 3300, New Zealand
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Turechek WW, Webster CG, Duan J, Roberts PD, Kousik CS, Adkins S. The use of latent class analysis to estimate the sensitivities and specificities of diagnostic tests for Squash vein yellowing virus in cucurbit species when there is no gold standard. PHYTOPATHOLOGY 2013; 103:1243-1251. [PMID: 23883156 DOI: 10.1094/phyto-03-13-0071-r] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Squash vein yellowing virus (SqVYV) is the causal agent of viral watermelon vine decline, one of the most serious diseases in watermelon (Citrullus lanatus L.) production in the southeastern United States. At present, there is not a gold standard diagnostic test for determining the true status of SqVYV infection in plants. Current diagnostic methods for identification of SqVYV-infected plants or tissues are based on the reverse-transcription polymerase chain reaction (RT-PCR), tissue blot nucleic acid hybridization assays (TB), and expression of visual symptoms. A quantitative assessment of the performance of these diagnostic tests is lacking, which may lead to an incorrect interpretation of results. In this study, latent class analysis (LCA) was used to estimate the sensitivities and specificities of RT-PCR, TB, and visual assessment of symptoms as diagnostic tests for SqVYV. The LCA model assumes that the observed diagnostic test responses are linked to an underlying latent (nonobserved) disease status of the population, and can be used to estimate sensitivity and specificity of the individual tests, as well as to derive an estimate of the incidence of disease when a gold standard test does not exist. LCA can also be expanded to evaluate the effect of factors and was done here to determine whether diagnostic test performances varied among the type of plant tissue being tested (crown versus vine tissue), where plant samples were taken relative to the position of the crown (i.e., distance from the crown), host (i.e., genus), and habitat (field-grown versus greenhouse-grown plants). Results showed that RT-PCR had the highest sensitivity (0.94) and specificity (0.98) of the three tests. TB had better sensitivity than symptoms for detection of SqVYV infection (0.70 versus 0.32), while the visual assessment of symptoms was more specific than TB and, thus, a better indicator of noninfection (0.98 versus 0.65). With respect to the grouping variables, RT-PCR and TB had better sensitivity but poorer specificity for diagnosing SqVYV infection in crown tissue than it did in vine tissue, whereas symptoms had very poor sensitivity but excellent specificity in both tissues for all cucurbits analyzed in this study. Test performance also varied with habitat and genus but not with distance from the crown. The results given here provide quantitative measurements of test performance for a range of conditions and provide the information needed to interpret test results when tests are used in parallel or serial combination for a diagnosis.
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Andritsos ND, Mataragas M, Paramithiotis S, Drosinos EH. Quantifying Listeria monocytogenes prevalence and concentration in minced pork meat and estimating performance of three culture media from presence/absence microbiological testing using a deterministic and stochastic approach. Food Microbiol 2013; 36:395-405. [DOI: 10.1016/j.fm.2013.06.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2013] [Accepted: 06/28/2013] [Indexed: 11/28/2022]
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Konigsberg LW, Frankenberg SR. Bayes in biological anthropology. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2013; 152 Suppl 57:153-84. [DOI: 10.1002/ajpa.22397] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Lyle W. Konigsberg
- Department of Anthropology; University of Illinois at Urbana-Champaign; Urbana IL 61801
| | - Susan R. Frankenberg
- Department of Anthropology; University of Illinois at Urbana-Champaign; Urbana IL 61801
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Ramilo A, Navas JI, Villalba A, Abollo E. Species-specific diagnostic assays for Bonamia ostreae and B. exitiosa in European flat oyster Ostrea edulis: conventional, real-time and multiplex PCR. DISEASES OF AQUATIC ORGANISMS 2013; 104:149-161. [PMID: 23709468 DOI: 10.3354/dao02597] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Bonamia ostreae and B. exitiosa have caused mass mortalities of various oyster species around the world and co-occur in some European areas. The World Organisation for Animal Health (OIE) has included infections with both species in the list of notifiable diseases. However, official methods for species-specific diagnosis of either parasite have certain limitations. In this study, new species-specific conventional PCR (cPCR) and real-time PCR techniques were developed to diagnose each parasite species. Moreover, a multiplex PCR method was designed to detect both parasites in a single assay. The analytical sensitivity and specificity of each new method were evaluated. These new procedures were compared with 2 OIE-recommended methods, viz. standard histology and PCR-RFLP. The new procedures showed higher sensitivity than the OIE recommended ones for the diagnosis of both species. The sensitivity of tests with the new primers was higher using oyster gills and gonad tissue, rather than gills alone. The lack of a 'gold standard' prevented accurate estimation of sensitivity and specificity of the new methods. The implementation of statistical tools (maximum likelihood method) for the comparison of the diagnostic tests showed the possibility of false positives with the new procedures, although the absence of a gold standard precluded certainty. Nevertheless, all procedures showed negative results when used for the analysis of oysters from a Bonamia-free area.
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Affiliation(s)
- Andrea Ramilo
- Centro de Investigacións Mariñas, Consellería do Medio Rural e do Mar, Xunta de Galicia, 36620 Vilanova de Arousa, Spain
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Agarwal R, Maskey D, Aggarwal AN, Saikia B, Garg M, Gupta D, Chakrabarti A. Diagnostic performance of various tests and criteria employed in allergic bronchopulmonary aspergillosis: a latent class analysis. PLoS One 2013; 8:e61105. [PMID: 23593402 PMCID: PMC3625190 DOI: 10.1371/journal.pone.0061105] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 03/05/2013] [Indexed: 01/18/2023] Open
Abstract
Aim The efficiency of various investigations and diagnostic criteria used in diagnosis of allergic bronchopulmonary aspergillosis (ABPA) remain unknown, primarily because of the lack of a gold standard. Latent class analysis (LCA) can provide estimates of sensitivity and specificity in absence of gold standard. Herein, we report the performance of various investigations and criteria employed in diagnosis of ABPA. Methods Consecutive subjects with asthma underwent all the following investigations Aspergillus skin test, IgE levels (total and A.fumigatus specific), Aspergillus precipitins, eosinophil count, chest radiograph, and high-resolution computed tomography (HRCT) of the chest. We used LCA to estimate the performance of various diagnostic tests and criteria in identification of ABPA. Results There were 372 asthmatics with a mean age of 35.9 years. The prevalence of Aspergillus sensitization was 53.2%. The sensitivity and specificity of various tests were Aspergillus skin test positivity (94.7%, 79.7%); IgE levels>1000 IU/mL (97.1%, 37.7%); A.fumigatus specific IgE levels>0.35 kUA/L (100%, 69.3%); Aspergillus precipitins (42.7%, 97.1%); eosinophil count>1000 cells/µL (29.5%, 93.1%); chest radiographic opacities (36.1%, 92.5%); bronchiectasis (91.9%, 80.9%); and, high-attenuation mucus (39.7%, 100%). The most accurate criteria was the Patterson criteria using six components followed by the Agarwal criteria. However, there was substantial decline in accuracy of the Patterson criteria if components of the criteria were either increased or decreased from six. Conclusions A.fumigatus specific IgE levels and high-attenuation mucus were found to be the most sensitive and specific test respectively in diagnosis of ABPA. The Patterson criteria remain the best diagnostic criteria however they have good veridicality only if six criteria are used.
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Affiliation(s)
- Ritesh Agarwal
- Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
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Bergman A, Heimer D, Kondori N, Enroth H. Fast and specific dermatophyte detection by automated DNA extraction and real-time PCR. Clin Microbiol Infect 2013; 19:E205-11. [DOI: 10.1111/1469-0691.12153] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 12/29/2012] [Accepted: 01/02/2013] [Indexed: 11/29/2022]
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Schroeder ME, Bounpheng MA, Rodgers S, Baker RJ, Black W, Naikare H, Velayudhan B, Sneed L, Szonyi B, Clavijo A. Development and performance evaluation of calf diarrhea pathogen nucleic acid purification and detection workflow. J Vet Diagn Invest 2013; 24:945-53. [PMID: 22914823 DOI: 10.1177/1040638712456976] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Calf diarrhea (scours) is a primary cause of illness and death in young calves. Significant economic losses associated with this disease include morbidity, mortality, and direct cost of treatment. Multiple pathogens are responsible for infectious diarrhea, including, but not limited to, Bovine coronavirus (BCV), bovine Rotavirus A (BRV), and Cryptosporidium spp. Identification and isolation of carrier calves are essential for disease management. Texas Veterinary Medical Diagnostic Laboratory current methods for calf diarrhea pathogen identification include electron microscopy (EM) for BCV and BRV and a direct fluorescent antibody test (DFAT) for organism detection of Cryptosporidium spp. A workflow was developed consisting of an optimized fecal nucleic acid purification and multiplex reverse transcription quantitative polymerase chain reaction (RT-qPCR) for single tube concurrent detection of BCV, BRV, and Cryptosporidium spp., and an internal control to monitor nucleic acid purification efficacy and PCR reagent functionality. In "spike-in" experiments using serial dilutions of each pathogen, the analytical sensitivity was determined to be <10 TCID(50)/ml for BCV and BRV, and <20 oocysts for Cryptosporidium spp. Analytical specificity was confirmed using Canine and Feline coronavirus, Giardia spp., and noninfected bovine purified nucleic acid. Diagnostic sensitivity was ≥98% for all pathogens when compared with respective traditional methods. The results demonstrate that the newly developed assay can purify and subsequently detect BCV, BRV, and Cryptosporidium spp. concurrently in a single PCR, enabling simplified and streamlined calf diarrhea pathogen identification.
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Affiliation(s)
- Megan E Schroeder
- Texas Veterinary Medical Diagnostic Laboratory, 1 Sippel Road, College Station, TX 77843, USA
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Machado de Assis TS, Rabello A, Werneck GL. Latent class analysis of diagnostic tests for visceral leishmaniasis in Brazil. Trop Med Int Health 2012; 17:1202-7. [DOI: 10.1111/j.1365-3156.2012.03064.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Andritsos ND, Mataragas M, Paramithiotis S, Nychas GJE, Drosinos EH. Estimating the diagnostic accuracy of three culture-dependent methods for the Listeria monocytogenes detection from a Bayesian perspective. Int J Food Microbiol 2012; 156:181-5. [PMID: 22507629 DOI: 10.1016/j.ijfoodmicro.2012.03.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 12/28/2011] [Accepted: 03/23/2012] [Indexed: 11/17/2022]
Abstract
The objective of this study was to estimate the test accuracy measures (classification probabilities [CPs], predictive values [PVs], likelihood ratios [LRs] and area under receiving operating characteristic curve [AUC]) of three different culture-dependent methods, commonly used during routine analysis for the detection of the foodborne pathogen Listeria monocytogenes, from a Bayesian perspective. Data from a previous study by Andritsos et al. (2010) were used to define measures of accuracy for the diagnostic tests. Samples of minced pork meat obtained from local markets were tested for L. monocytogenes presence by parallel testing using selective media (PALCAM, ALOA and RAPID'L.mono). Dirichlet distribution, which is the multivariate expression of a Beta distribution, was used to analyze the data. Bayesian analysis determines characteristics of the posterior distribution from available prior information. Results showed that all methods were best at ruling in L. monocytogenes presence than ruling it out. PALCAM seemed to have better performance based on positive PV, positive LR and AUC, but it was not so sensitive as RAPID'L.mono was. Results also showed that none of the media were perfect in detecting L. monocytogenes, i.e. sensitivity and specificity equal to one. Besides, the problem of observing zero counts may be overcome by applying Bayesian analysis, making the determination of a test performance feasible.
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Affiliation(s)
- Nikolaos D Andritsos
- Laboratory of Food Quality Control and Hygiene, Department of Food Science and Technology, Agricultural University of Athens, Iera Odos 75, GR-118 55 Athens, Greece
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Horigan MW, Bell MM, Pollard TR, Sayers AR, Pritchard GC. Q fever diagnosis in domestic ruminants: comparison between complement fixation and commercial enzyme-linked immunosorbent assays. J Vet Diagn Invest 2012; 23:924-31. [PMID: 21908348 DOI: 10.1177/1040638711416971] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Q fever is an important zoonotic disease caused by infection with the bacterium Coxiella burnetii. Veterinary diagnostic laboratories, including the Veterinary Laboratories Agency (VLA) in England and Wales, have traditionally relied on the complement fixation test (CFT) for serological diagnosis. However, Q fever has assumed greater significance in recent years following several large human outbreaks linked to exposure to infected ruminants and it is essential that more reliable tests are introduced to detect the presence of C. burnetii infection in animals. The objective of the current study was to evaluate the performance of 3 commercially available enzyme-linked immunosorbent assays (ELISAs) for detection of antibodies to C. burnetii and to compare the findings with the CFT using a sample panel of 548 sera from sheep, goats, and cattle, including animals of known disease status. The statistical analysis using TAGS (test accuracy in the absence of a gold standard) software and receiver operating characteristic techniques demonstrated that the 3 ELISAs all showed improved sensitivity over the CFT. The test based on ovine antigen demonstrated the best overall performance and therefore, the VLA has adopted this test for routine use.
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Affiliation(s)
- Mark W Horigan
- Veterinary Laboratories Agency, New Haw, Addlestone, Surrey KT15 3NB, UK.
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Borsuk S, Andreotti R, Leite FPL, da Silva Pinto L, Simionatto S, Hartleben CP, Goetze M, Oshiro LM, Matos MDFC, Berne MEA. Development of an indirect ELISA-NcSRS2 for detection of Neospora caninum antibodies in cattle. Vet Parasitol 2011; 177:33-8. [DOI: 10.1016/j.vetpar.2010.11.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Revised: 11/11/2010] [Accepted: 11/15/2010] [Indexed: 11/24/2022]
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Gardner IA, Greiner M, Dubey JP. Statistical evaluation of test accuracy studies for Toxoplasma gondii in food animal intermediate hosts. Zoonoses Public Health 2009; 57:82-94. [PMID: 19744298 DOI: 10.1111/j.1863-2378.2009.01281.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The availability of accurate diagnostic tests is essential for the detection and control of Toxoplasma gondii infections in both definitive and intermediate hosts. Sensitivity, specificity and the area under the receiver-operating characteristic (ROC) curve are commonly used measures of test accuracy for infectious diseases such as toxoplasmosis. These test performance characteristics are important considerations when selecting from among a group of tests for a specific testing purpose. In this study, we reviewed statistical approaches to evaluation of tests for toxoplasmosis with and without a gold-standard (reference) test, including use of ROC analysis and likelihood ratios which retain the diagnostic information inherent in a quantitative test result. We use previously published data from a comparison of the accuracy of serological tests for swine toxoplasmosis to demonstrate suggested methods of data analysis. We make recommendations for statistical analysis and reporting of test evaluation studies for T. gondii in food animals based on our own experiences and those of others.
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Affiliation(s)
- I A Gardner
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
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Martinez EZ, Louzada-Neto F, Achcar JA, Syrjänen KJ, Derchain SFM, Gontijo RC, Sarian LOZ. Bayesian estimation of performance measures of screening tests in the presence of covariates and absence of a gold standard. BRAZ J PROBAB STAT 2009. [DOI: 10.1214/08-bjps006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Drewe JA, Dean GS, Michel AL, Lyashchenko KP, Greenwald R, Pearce GP. Accuracy of three diagnostic tests for determining Mycobacterium bovis infection status in live-sampled wild meerkats (Suricata suricatta). J Vet Diagn Invest 2009; 21:31-9. [PMID: 19139498 DOI: 10.1177/104063870902100105] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Accurate diagnosis of Mycobacterium bovis infection (bovine tuberculosis [bTB]) in live animals is notoriously problematic. The aim of the present study was to evaluate the diagnostic potential of 2 new serologic tests (multiantigen print immunoassay [MAPIA] and lateral flow immunoassay rapid test [RT]) in comparison with mycobacterial culture of tracheal washes for determining M. bovis infection status in a free-ranging population of wild meerkats (Suricata suricatta). During a longitudinal study lasting 2.5 years, 240 individually identifiable meerkats were each sampled up to 8 times under anesthesia every 3 months. Diagnostic accuracy was determined through Bayesian and maximum likelihood estimations of sensitivity, specificity, and likelihood ratios for each diagnostic test when used independently and in parallel to classify the disease status of individual meerkats in the absence of a gold standard. Culture of tracheal washes was highly specific (0.99; 95% confidence interval [CI] = 0.77, 1.00) but of low sensitivity (0.36; 95% CI = 0.24, 0.50) for diagnosing M. bovis-infected individuals. The longitudinal nature of the study with repeated sampling of the same individual animals served simultaneously to improve chances of detecting infection and increase confidence in a negative result in individual animals repeatedly testing negative. Although MAPIA and RT were individually of limited diagnostic use, interpreting the results of these 2 tests in parallel produced estimates of sensitivity (0.83; 95% CI = 0.67, 0.93) and specificity (0.73; 95% CI = 0.62, 0.82) high enough to usefully inform decision making when determining exposure to bTB in wild meerkats and potentially other species in which bTB poses a diagnostic challenge.
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Affiliation(s)
- Julian A Drewe
- Department of Veterinary Medicine, Wildlife Health and Conservation Medicine Group, University of Cambridge, Cambridge, UK.
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Alinovi CA, Ward MP, Lin TL, Moore GE, Wu CC. Real-time PCR, compared to liquid and solid culture media and ELISA, for the detection of Mycobacterium avium ssp. paratuberculosis. Vet Microbiol 2009; 136:177-9. [DOI: 10.1016/j.vetmic.2008.10.012] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Revised: 10/12/2008] [Accepted: 10/16/2008] [Indexed: 10/21/2022]
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Poynard T, Ingiliz P, Elkrief L, Munteanu M, Lebray P, Morra R, Messous D, Bismut FI, Roulot D, Benhamou Y, Thabut D, Ratziu V. Concordance in a world without a gold standard: a new non-invasive methodology for improving accuracy of fibrosis markers. PLoS One 2008; 3:e3857. [PMID: 19052646 PMCID: PMC2586659 DOI: 10.1371/journal.pone.0003857] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2008] [Accepted: 11/08/2008] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Assessing liver fibrosis is traditionally performed by biopsy, an imperfect gold standard. Non-invasive techniques, liver stiffness measurements (LSM) and biomarkers [FibroTest(R) (FT)], are widely used in countries where they are available. The aim was to identify factors associated with LSM accuracy using FT as a non-invasive endpoint and vice versa. METHODS The proof of concept was taken using the manufacturers recommendations for excluding patients at high risk of false negative/positive. The hypothesis was that the concordance between LSM and FT, would be improved by excluding high-risk patients. Thereafter, the impact of potential variability factors was assessed by the same methods. Liver biopsy and independent endpoints were used to validate the results. RESULTS Applying manufacturers' recommendations in 2,004 patients increased the strength of concordance between LSM and FT (P<0.00001). Among the 1,338 patients satisfying recommendations, the methodology identified a significant LSM operator effect (P = 0.001) and the following variability factors (all P<0.01), related to LSM: male gender, older age, and NAFLD as a cause of liver disease. Biopsy confirmed in 391 patients these results. CONCLUSION This study has validated the concept of using the strength of concordance between non-invasive estimates of liver fibrosis for the identification of factors associated with variability and precautions of use.
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Affiliation(s)
- Thierry Poynard
- APHP Groupe Hospitalier Pitié-Salpêtrière, Université Paris VI, CNRS UMR, Paris, France.
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Gari G, Biteau-Coroller F, LeGoff C, Caufour P, Roger F. Evaluation of indirect fluorescent antibody test (IFAT) for the diagnosis and screening of lumpy skin disease using Bayesian method. Vet Microbiol 2008; 129:269-80. [DOI: 10.1016/j.vetmic.2007.12.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Revised: 11/28/2007] [Accepted: 12/05/2007] [Indexed: 11/26/2022]
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Rodulfo H, De Donato M, Mora R, González L, Contreras CE. Comparison of the diagnosis of malaria by microscopy, immunochromatography and PCR in endemic areas of Venezuela. Braz J Med Biol Res 2008; 40:535-43. [PMID: 17401497 DOI: 10.1590/s0100-879x2007000400012] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2005] [Accepted: 01/09/2007] [Indexed: 11/21/2022] Open
Abstract
Whole blood samples (N = 295) were obtained from different locations in Amazonas and Sucre States, in Venezuela. Malaria was diagnosed by microscopy, OptiMAL and polymerase chain reaction (PCR), with Plasmodium vivax, P. falciparum, and P. malariae being detected when possible. We identified 93 infections, 66 of which were caused by P. vivax, 26 by P. falciparum, and 1 was a mixed infection. No infection caused by P. malariae was detected. The sensitivity and specificity of each diagnostic method were high: 95.7 and 97.9% for microscopy, 87.0 and 97.9% for OptiMAL, and 98.0 and 100% for PCR, respectively. Most samples (72.2%) showed more than 5000 parasites/microL blood. The sensitivity of the diagnosis by microscopy and OptiMAL decreased with lower parasitemia. All samples showing disagreement among the methods were reevaluated, but the first result was used for the calculations. Parasites were detected in the 6 false-negative samples by microscopy after the second examination. The mixed infection was only detected by PCR, while the other methods diagnosed it as P. falciparum (microscopy) or P. vivax (OptiMAL) infection. Most of the false results obtained with the OptiMAL strip were related to the P. falciparum-specific band, including 3 species misdiagnoses, which could be related to the test itself or to genetic variation of the Venezuelan strains. The use of the microscopic method for malaria detection is recommended for its low cost but is very difficult to implement in large scale, population-based studies; thus, we report here more efficient methods suitable for this purpose.
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Affiliation(s)
- H Rodulfo
- Laboratorio de Genética Molecular, Departamento de Biomedicina, Instituto de Investigaciones en Biomedicina y Ciencias Aplicadas, Universidad de Oriente, Cumaná, Venezuela
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Stamey JD, Boese DH, Young DM. Confidence intervals for parameters of two diagnostic tests in the absence of a gold standard. Comput Stat Data Anal 2008. [DOI: 10.1016/j.csda.2007.08.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Ogunremi O, Halbert G, Mainar-Jaime R, Benjamin J, Pfister K, Lopez-Rebollar L, Georgiadis MP. Accuracy of an indirect fluorescent-antibody test and of a complement-fixation test for the diagnosis of Babesia caballi in field samples from horses. Prev Vet Med 2007; 83:41-51. [PMID: 17707933 DOI: 10.1016/j.prevetmed.2007.06.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2006] [Revised: 06/02/2007] [Accepted: 06/09/2007] [Indexed: 10/22/2022]
Abstract
We evaluated the indirect fluorescent-antibody (IFA) test and complement-fixation (CF) test for diagnosis of equine piroplasmosis in the absence of a gold standard. Using Evan's blue, we estimated the specificity of the IFA test on a parasite-free, field horse population to be 98% (95% confidence interval=97, 99). We observed an excellent test agreement (kappa=0.83) between two collaborating laboratories when the IFA test was performed on identical samples from an endemic area. Using Bayesian analysis with informative prior probability distributions, we estimated the sensitivity of the IFA test to be 92% (95% probability interval, PI=81, 98), and specificity to be 95% (95% PI=88, 99). The CF test sensitivity and specificity estimates were 28% (95% PI=15, 47) and 99% (95% PI=96, 100), respectively. We found the IFA to be superior to the CF test, and the inclusion of Evan's blue in test protocol improved the performance of the IFA test. We conclude that the IFA test for Babesia caballi is a sensitive and specific test for the diagnosis of equine piroplasmosis.
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Affiliation(s)
- Oladele Ogunremi
- Centre for Food-borne and Animal Parasitology, Canadian Food Inspection Agency, Saskatoon Laboratory, 116 Veterinary Road, Saskatoon, Canada, S7N 2R3.
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Dabritz HA, Gardner IA, Miller MA, Lappin MR, Atwill ER, Packham AE, Melli AC, Conrad PA. EVALUATION OF TWO TOXOPLASMA GONDII SEROLOGIC TESTS USED IN A SEROSURVEY OF DOMESTIC CATS IN CALIFORNIA. J Parasitol 2007; 93:806-16. [DOI: 10.1645/ge-996r.1] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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van Schaik G, Haro F, Mella A, Kruze J. Bayesian analysis to validate a commercial ELISA to detect paratuberculosis in dairy herds of southern Chile. Prev Vet Med 2006; 79:59-69. [PMID: 17188381 DOI: 10.1016/j.prevetmed.2006.11.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In Chile, Mycobacterium avium subsp. paratuberculosis (Map) has been isolated on several occasions and clinical cases have been reported. Nevertheless, diagnostic tests have not yet been validated for this agent in the Chilean setting. The objective of the study was to validate a commercial ELISA to detect Map shedding dairy cows in management conditions, prevalence and stages of infection existing in Southern Chile, utilising different statistical approaches. Blood and faeces were collected from 1333 lactating cows in 27 dairy herds (both large commercial and smallholder dairy farms) between September 2003 and August 2004. Within the herds up to a maximum of 100 dairy cows were selected based on age (>or=3 years old) and, if present, clinical signs of a Map infection. In herds with less than 100 cows, all cows >or=3 years old were sampled. Blood samples were tested using a commercial ELISA kit (IDEXX Laboratories, Inc.). Faecal samples were cultured on Herrold's Egg Yolk Medium (HEYM). Latent class models (i.e. maximum likelihood (ML) methods and Bayesian inference) were used to determine the validity of the ELISA. Map was cultured from 54 (4.1%) cows and 10 (37.0%) herds, which were all large, commercial dairy herds. As a result of empty cells in the cross-tabulations, the ML model provided the same results as the validation with faecal culture as the gold-standard. In the Bayesian model, the Se and Sp of the ELISA were estimated to be 26% (95% CI: 18-35%) and 98.5% (95% CI: 97.4-99.4%), respectively. For faecal culture, the Se was 54% (95% CI: 46-62%) and the Sp was 100% (95% CI: 99.9-100%). Interestingly, the prevalence in the smallholder dairy farms was estimated to be 8% even though there were no faecal culture positive cows detected in those herds. There was no significant correlation between the two tests. The advantage of Bayesian inference is that the Se and Sp of both tests are obtained in one model relative to the (latent) true disease status, the model can handle small datasets and empty cells and the estimates can be corrected for the correlation between tests when the tests are not conditionally independent. Therefore, Bayesian analysis was the preferred method for Map that lacks a gold-standard and usually has low cow-level prevalence.
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Affiliation(s)
- G van Schaik
- Instituto de Medicina Preventiva, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, Chile.
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Engel B, Swildens B, Stegeman A, Buist W, Jong M. Estimation of sensitivity and specificity of three conditionally dependent diagnostic tests in the absence of a gold standard. JOURNAL OF AGRICULTURAL BIOLOGICAL AND ENVIRONMENTAL STATISTICS 2006. [DOI: 10.1198/108571106x153534] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Biteau-Coroller F, Gerbier G, Stärk KDC, Grillet C, Albina E, Zientara S, Roger F. Performance evaluation of a competitive ELISA test used for Bluetongue antibody detection in France, a recently infected area. Vet Microbiol 2006; 118:57-66. [PMID: 16979306 DOI: 10.1016/j.vetmic.2006.07.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Revised: 06/30/2006] [Accepted: 07/13/2006] [Indexed: 11/29/2022]
Abstract
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.
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Affiliation(s)
- Fabienne Biteau-Coroller
- CIRAD, Centre de Coopération Internationale en Recherche Agronomique pour le Développement, Département D'élevage et de Médecine Vétérinaire, TA 30/E, Campus International de Baillarguet, F-34398 Montpellier Cedex 5, France.
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Michael E, Malecela-Lazaro MN, Maegga BTA, Fischer P, Kazura JW. Mathematical models and lymphatic filariasis control: monitoring and evaluating interventions. Trends Parasitol 2006; 22:529-35. [PMID: 16971182 DOI: 10.1016/j.pt.2006.08.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2005] [Revised: 07/17/2006] [Accepted: 08/30/2006] [Indexed: 10/24/2022]
Abstract
Monitoring and evaluation are crucially important to the scientific management of any mass parasite control programme. Monitoring enables the effectiveness of implemented actions to be assessed and necessary adaptations to be identified; it also determines when management objectives are achieved. Parasite transmission models can provide a scientific template for informing the optimal design of such monitoring programmes. Here, we illustrate the usefulness of using a model-based approach for monitoring and evaluating anti-parasite interventions and discuss issues that need addressing. We focus on the use of such an approach for the control and/or elimination of the vector-borne parasitic disease, lymphatic filariasis.
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Affiliation(s)
- Edwin Michael
- Department of Infectious Disease Epidemiology, Imperial College School of Medicine, Norfolk Place, London, W2 1PG, UK.
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