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Bodenham RF, Mazeri S, Cleaveland S, Crump JA, Fasina FO, de Glanville WA, Haydon DT, Kazwala RR, Kibona TJ, Maro VP, Maze MJ, Mmbaga BT, Mtui-Malamsha NJ, Shirima GM, Swai ES, Thomas KM, Bronsvoort BMD, Halliday JEB. Latent class evaluation of the performance of serological tests for exposure to Brucella spp. in cattle, sheep, and goats in Tanzania. PLoS Negl Trop Dis 2021; 15:e0009630. [PMID: 34428205 PMCID: PMC8384210 DOI: 10.1371/journal.pntd.0009630] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 07/06/2021] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Brucellosis is a neglected zoonosis endemic in many countries, including regions of sub-Saharan Africa. Evaluated diagnostic tools for the detection of exposure to Brucella spp. are important for disease surveillance and guiding prevention and control activities. METHODS AND FINDINGS Bayesian latent class analysis was used to evaluate performance of the Rose Bengal plate test (RBT) and a competitive ELISA (cELISA) in detecting Brucella spp. exposure at the individual animal-level for cattle, sheep, and goats in Tanzania. Median posterior estimates of RBT sensitivity were: 0.779 (95% Bayesian credibility interval (BCI): 0.570-0.894), 0.893 (0.636-0.989), and 0.807 (0.575-0.966), and for cELISA were: 0.623 (0.443-0.790), 0.409 (0.241-0.644), and 0.561 (0.376-0.713), for cattle, sheep, and goats, respectively. Sensitivity BCIs were wide, with the widest for cELISA in sheep. RBT and cELISA median posterior estimates of specificity were high across species models: RBT ranged between 0.989 (0.980-0.998) and 0.995 (0.985-0.999), and cELISA between 0.984 (0.974-0.995) and 0.996 (0.988-1). Each species model generated seroprevalence estimates for two livestock subpopulations, pastoralist and non-pastoralist. Pastoralist seroprevalence estimates were: 0.063 (0.045-0.090), 0.033 (0.018-0.049), and 0.051 (0.034-0.076), for cattle, sheep, and goats, respectively. Non-pastoralist seroprevalence estimates were below 0.01 for all species models. Series and parallel diagnostic approaches were evaluated. Parallel outperformed a series approach. Median posterior estimates for parallel testing were ≥0.920 (0.760-0.986) for sensitivity and ≥0.973 (0.955-0.992) for specificity, for all species models. CONCLUSIONS Our findings indicate that Brucella spp. surveillance in Tanzania using RBT and cELISA in parallel at the animal-level would give high test performance. There is a need to evaluate strategies for implementing parallel testing at the herd- and flock-level. Our findings can assist in generating robust Brucella spp. exposure estimates for livestock in Tanzania and wider sub-Saharan Africa. The adoption of locally evaluated robust diagnostic tests in setting-specific surveillance is an important step towards brucellosis prevention and control.
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Affiliation(s)
- Rebecca F. Bodenham
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- * E-mail: ,
| | - Stella Mazeri
- The Epidemiology, Economics and Risk Assessment (EERA) group, The Roslin Institute and The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Sarah Cleaveland
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - John A. Crump
- Duke Global Health Institute, Duke University, Durham, North Carolina, United States of America
- Kilimanjaro Christian Medical Centre, Moshi, Tanzania
- Kilimanjaro Clinical Research Institute, Moshi, Tanzania
- Centre for International Health, University of Otago, Dunedin, New Zealand
- Kilimanjaro Christian Medical University College, Moshi, Tanzania
- Division of Infectious Diseases and International Health, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Folorunso O. Fasina
- Emergency Centre for Transboundary Animal Diseases, Food and Agriculture Organization (FAO) of the United Nations, Dar es Salaam, Tanzania
- Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South Africa
| | - William A. de Glanville
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Daniel T. Haydon
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | | | - Tito J. Kibona
- Nelson Mandela African Institution for Science and Technology, Arusha, Tanzania
| | - Venance P. Maro
- Kilimanjaro Christian Medical Centre, Moshi, Tanzania
- Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Michael J. Maze
- Centre for International Health, University of Otago, Dunedin, New Zealand
- Department of Medicine, University of Otago, Christchurch, New Zealand
| | - Blandina T. Mmbaga
- Duke Global Health Institute, Duke University, Durham, North Carolina, United States of America
- Kilimanjaro Christian Medical Centre, Moshi, Tanzania
- Kilimanjaro Clinical Research Institute, Moshi, Tanzania
- Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Niwael J. Mtui-Malamsha
- Emergency Centre for Transboundary Animal Diseases, Food and Agriculture Organization (FAO) of the United Nations, Dar es Salaam, Tanzania
| | - Gabriel M. Shirima
- Nelson Mandela African Institution for Science and Technology, Arusha, Tanzania
| | - Emanuel S. Swai
- Directorate of Veterinary Services, Ministry of Livestock and Fisheries, Dodoma, Tanzania
| | - Kate M. Thomas
- Kilimanjaro Clinical Research Institute, Moshi, Tanzania
- Centre for International Health, University of Otago, Dunedin, New Zealand
| | - Barend M. deC. Bronsvoort
- The Epidemiology, Economics and Risk Assessment (EERA) group, The Roslin Institute and The Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Jo E. B. Halliday
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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Swai ES, Schoonman L. A survey of zoonotic diseases in trade cattle slaughtered at Tanga city abattoir: a cause of public health concern. Asian Pac J Trop Biomed 2015; 2:55-60. [PMID: 23569835 DOI: 10.1016/s2221-1691(11)60190-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 06/05/2011] [Accepted: 06/24/2011] [Indexed: 11/28/2022] Open
Abstract
OBJECTIVE To estimate the prevalence of hydatidosis, cysticercosis, tuberculosis, leptospirosis, brucellosis and toxoplasmosis in slaughtered bovine stock (aged ±3 years) at Tanga city abattoir, Tanzania. METHODS Prevalence estimation of the five zoonotic diseases was undertaken through an active abattoir and sero-survey was carried out in Tanga city, during the period of January 2002 and March 2004. Serum samples collected from a sub-sample (n=51) of the slaughter stock were serologically screened for antibodies against brucellosis, leptospirosis and toxoplasmosis using Rose Bengal plate test, microscopic agglutination test (for 5 serovars of Leptospira interrogans) and Eiken latex agglutination test, respectively. The same animals were tested for tuberculosis using the single intradermal tuberculin test. RESULTS Post mortem examination of 12 444 slaughter cattle (10 790 short horn zebu and 1 654 graded) over a period of twenty two months, showed a prevalence of 1.56% (194) for hydatidosis, 1.49% (185) for cysticercosis and 0.32% (40) for tuberculosis. In all three zoonoses, a statistically significant difference in infection rates was noted between the short horn zebu and graded breeds (P<0.05). The overall seroprevalences of animals with brucellosis, toxoplasmosis and leptospirosis antibodies were found to be 12%, 12% and 51%, respectively. The most common leptospiral antibodies detected were those against antigens of serovars Leptospira hardjo (29%), Leptospira tarassovi (18%), Leptospira bataviae (4%) and Leptospira pomona (0%). With regard to tuberculosis, 10% (n=5) of the animals tested were classified as non-specific reactors or inconclusive. CONCLUSIONS The study findings suggest that brucellosis, toxoplasmosis and leptospirosis are prevalent in Tanga and provide definitive evidence of slaughtered stock exposure to these zoonotic agents with concurrent public health consequences.
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Affiliation(s)
- E S Swai
- Veterinary Investigation Centre (VIC), Box 1068, Arusha, Tanzania
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Rahman AKMA, Saegerman C, Berkvens D, Fretin D, Gani MO, Ershaduzzaman M, Ahmed MU, Emmanuel A. Bayesian estimation of true prevalence, sensitivity and specificity of indirect ELISA, Rose Bengal Test and Slow Agglutination Test for the diagnosis of brucellosis in sheep and goats in Bangladesh. Prev Vet Med 2012; 110:242-52. [PMID: 23276401 DOI: 10.1016/j.prevetmed.2012.11.029] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 11/29/2012] [Accepted: 11/30/2012] [Indexed: 11/16/2022]
Abstract
The true prevalence of brucellosis and diagnostic test characteristics of three conditionally dependent serological tests were estimated using the Bayesian approach in goats and sheep populations of Bangladesh. Serum samples from a random selection of 636 goats and 1044 sheep were tested in parallel by indirect ELISA (iELISA), Rose Bengal Test (RBT) and Slow Agglutination Test (SAT). The true prevalence of brucellosis in goats and sheep were estimated as 1% (95% credibility interval (CrI): 0.7-1.8) and 1.2% (95% CrI: 0.6-2.2) respectively. The sensitivity of iELISA was 92.9% in goats and 92.0% in sheep with corresponding specificities of 96.5% and 99.5% respectively. The sensitivity and specificity estimates of RBT were 80.2% and 99.6% in goats and 82.8% and 98.3% in sheep. The sensitivity and specificity of SAT were 57.1% and 99.3% in goats and 72.0% and 98.6% in sheep. In this study, three conditionally dependent serological tests for the diagnosis of small ruminant brucellosis in Bangladesh were validated. Considerable conditional dependence between IELISA and RBT and between RBT and SAT was observed among sheep. The influence of the priors on the model fit and estimated parameter values was checked using sensitivity analysis. In multiple test validation, conditional dependence should not be ignored when the tests are in fact conditionally dependent.
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Affiliation(s)
- A K M Anisur Rahman
- Department of Medicine, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh.
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Large scale immune profiling of infected humans and goats reveals differential recognition of Brucella melitensis antigens. PLoS Negl Trop Dis 2010; 4:e673. [PMID: 20454614 PMCID: PMC2864264 DOI: 10.1371/journal.pntd.0000673] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Accepted: 03/19/2010] [Indexed: 01/18/2023] Open
Abstract
Brucellosis is a widespread zoonotic disease that is also a potential agent of bioterrorism. Current serological assays to diagnose human brucellosis in clinical settings are based on detection of agglutinating anti-LPS antibodies. To better understand the universe of antibody responses that develop after B. melitensis infection, a protein microarray was fabricated containing 1,406 predicted B. melitensis proteins. The array was probed with sera from experimentally infected goats and naturally infected humans from an endemic region in Peru. The assay identified 18 antigens differentially recognized by infected and non-infected goats, and 13 serodiagnostic antigens that differentiate human patients proven to have acute brucellosis from syndromically similar patients. There were 31 cross-reactive antigens in healthy goats and 20 cross-reactive antigens in healthy humans. Only two of the serodiagnostic antigens and eight of the cross-reactive antigens overlap between humans and goats. Based on these results, a nitrocellulose line blot containing the human serodiagnostic antigens was fabricated and applied in a simple assay that validated the accuracy of the protein microarray results in the diagnosis of humans. These data demonstrate that an experimentally infected natural reservoir host produces a fundamentally different immune response than a naturally infected accidental human host. Brucellosis is a bacterial disease transmitted from infected animals to humans. This disease often presents as a prolonged but non-specific illness primarily characterized as fever without specific organ localization. Because infections can result after ingestion (typically from unpasteurized animal milk or milk products from goats, cattle or sheep) or inhalation (important because of bioterrorism potential) of small numbers of organisms, the bacteria that cause brucellosis are potential biological warfare agents. Here, a protein microarray containing 1406 Brucella melitensis proteins was used to study the antibody response of experimentally infected goats and naturally infected humans in B. melitensis infection. Goats recognized 18 proteins and humans recognized 13 proteins as serodiagnostic antigens; antibody detection of only two of these antigens was shared by goats and humans, suggesting either fundamentally different immune responses or different responses in relation to mode or setting of infection. The human serodiagnostic antigens were evaluated in a simple nitrocellulose line blot assay, which validated the protein microarray results. The approach described here will lead to the development of new diagnostics for brucellosis and other infectious diseases, and aid in understanding the human and animal host immune response to pathogenic organisms.
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