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Teferi M, Desta M, Yeshitela B, Beyene T, Cruz Espinoza LM, Im J, Jeon HJ, Kim JH, Konings F, Kwon SY, Pak GD, Park JK, Park SE, Yedenekachew M, Kim J, Baker S, Sir WS, Marks F, Aseffa A, Panzner U. Acute Febrile Illness Among Children in Butajira, South-Central Ethiopia During the Typhoid Fever Surveillance in Africa Program. Clin Infect Dis 2020; 69:S483-S491. [PMID: 31665778 PMCID: PMC6821253 DOI: 10.1093/cid/ciz620] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Background Clearly differentiating causes of fever is challenging where diagnostic capacities are limited, resulting in poor patient management. We investigated acute febrile illness in children aged ≤15 years enrolled at healthcare facilities in Butajira, Ethiopia, during January 2012 to January 2014 for the Typhoid Fever Surveillance in Africa Program. Methods Blood culture, malaria microscopy, and blood analyses followed by microbiological, biochemical, and antimicrobial susceptibility testing of isolates were performed. We applied a retrospectively developed scheme to classify children as malaria or acute respiratory, gastrointestinal or urinary tract infection, or other febrile infections and syndromes. Incidence rates per 100 000 population derived from the classification scheme and multivariate logistic regression to determine fever predictors were performed. Results We rarely observed stunting (4/513, 0.8%), underweight (1/513, 0.2%), wasting (1/513, 0.2%), and hospitalization (21/513, 4.1%) among 513 children with mild transient fever and a mean disease severity score of 12 (95% confidence interval [CI], 11–13). Blood cultures yielded 1.6% (8/513) growth of pathogenic agents; microscopy detected 13.5% (69/513) malaria with 20 611/µL blood (95% CI, 15 352–25 870) mean parasite density. Incidences were generally higher in children aged ≤5 years than >5 to ≤15 years; annual incidences in young children were 301.3 (95% CI, 269.2–337.2) for malaria and 1860.1 (95% CI, 1778.0–1946.0) for acute respiratory and 379.9 (95% CI, 343.6–420.0) for gastrointestinal tract infections. Conclusions We could not detect the etiological agents in all febrile children. Our findings may prompt further investigations and the reconsideration of policies and frameworks for the management of acute febrile illness.
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Affiliation(s)
- Mekonnen Teferi
- Armauer Hansen Research Institute, Ministry of Health, Addis Ababa, Ethiopia
| | - Mulualem Desta
- International Vaccine Institute, Seoul, South Korea.,Technology and Innovation Institute, Addis Ababa, Ethiopia.,Graduate School of Public Health, Yonsei University, Seoul, South Korea
| | - Biruk Yeshitela
- Armauer Hansen Research Institute, Ministry of Health, Addis Ababa, Ethiopia
| | - Tigist Beyene
- Armauer Hansen Research Institute, Ministry of Health, Addis Ababa, Ethiopia
| | | | - Justin Im
- International Vaccine Institute, Seoul, South Korea
| | | | | | | | | | - Gi Deok Pak
- International Vaccine Institute, Seoul, South Korea
| | | | - Se Eun Park
- International Vaccine Institute, Seoul, South Korea.,Hospital for Tropical Diseases, Welcome Trust Major Overseas Program, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
| | - Melaku Yedenekachew
- Armauer Hansen Research Institute, Ministry of Health, Addis Ababa, Ethiopia
| | - Jerome Kim
- International Vaccine Institute, Seoul, South Korea
| | - Stephen Baker
- Hospital for Tropical Diseases, Welcome Trust Major Overseas Program, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam.,Department of Medicine, University of Cambridge, United Kingdom
| | - Won Seok Sir
- Graduate School of Public Health, Yonsei University, Seoul, South Korea
| | - Florian Marks
- International Vaccine Institute, Seoul, South Korea.,Department of Medicine, University of Cambridge, United Kingdom
| | - Abraham Aseffa
- Armauer Hansen Research Institute, Ministry of Health, Addis Ababa, Ethiopia
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Bundalian R, Valenzuela M, Tiongco RE. Achieving accurate laboratory diagnosis of typhoid fever: a review and meta-analysis of TUBEX® TF clinical performance. Pathog Glob Health 2019; 113:297-308. [PMID: 31778097 DOI: 10.1080/20477724.2019.1695081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
This review discusses currently available serological diagnostic methods for typhoid fever with a focus on the clinical utility of TUBEX® TF as an alternative to the Widal or Typhidot test. A literature search was conducted in PubMed for related publications written in English. A qualitative analysis was done to determine various serological tests used for typhoid fever diagnosis with emphasis on TUBEX® TF in comparison to the Widal of Typhidot test. Further, a meta-analysis was performed to obtain a pooled estimate of diagnostic accuracy (sensitivity and specificity) using different analysis models. A total of sixteen studies was included in the qualitative analysis. Further screening of these studies yielded ten studies that were used for the meta-analysis. The sensitivity/specificity range of different commonly used serological tests in typhoid patients is between 55-100%/58-100% for TUBEX® TF, 54-67%/54-95% for Typhidot, and 32-95%/4-98% for the Widal test. As for the pooled meta-analysis estimates, the TUBEX® TF showed superior results when differentiating individuals with febrile illness of unknown origin from those with typhoid fever. Overall, the results of this review and meta-analysis suggest that the TUBEX® TF is more advantageous to use as a serological test for typhoid fever diagnosis due its accuracy and simplicity. However, further studies are still needed to validate our results.
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Affiliation(s)
- Reynaldo Bundalian
- Center for Research and Development, Angeles University Foundation, Angeles City, Philippines
| | - Madonna Valenzuela
- Public Health Program, Graduate School, Angeles University Foundation, Angeles City, Philippines
| | - Raphael Enrique Tiongco
- Department of Medical Technology, College of Allied Medical Professions, Angeles University Foundation, Angeles City, Philippines
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3
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Osorio L, Garcia JA, Parra LG, Garcia V, Torres L, Degroote S, Ridde V. A scoping review on the field validation and implementation of rapid diagnostic tests for vector-borne and other infectious diseases of poverty in urban areas. Infect Dis Poverty 2018; 7:87. [PMID: 30173662 PMCID: PMC6120097 DOI: 10.1186/s40249-018-0474-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 08/01/2018] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Health personnel face challenges in diagnosing vector-borne and other diseases of poverty in urban settings. There is a need to know what rapid diagnostic technologies are available, have been properly assessed, and are being implemented to improve control of these diseases in the urban context. This paper characterizes evidence on the field validation and implementation in urban areas of rapid diagnostics for vector-borne diseases and other diseases of poverty. MAIN BODY A scoping review was conducted. Peer-reviewed and grey literature were searched using terms describing the targeted infectious diseases, diagnostics evaluations, rapid tests, and urban setting. The review was limited to studies published between 2000 and 2016 in English, Spanish, French, and Portuguese. Inclusion and exclusion criteria were refined post hoc to identify relevant literature regardless of study design and geography. A total of 179 documents of the 7806 initially screened were included in the analysis. Malaria (n = 100) and tuberculosis (n = 47) accounted for the majority of studies that reported diagnostics performance, impact, and implementation outcomes. Fewer studies, assessing mainly performance, were identified for visceral leishmaniasis (n = 9), filariasis and leptospirosis (each n = 5), enteric fever and schistosomiasis (each n = 3), dengue and leprosy (each n = 2), and Chagas disease, human African trypanosomiasis, and cholera (each n = 1). Reported sensitivity of rapid tests was variable depending on several factors. Overall, specificities were high (> 80%), except for schistosomiasis and cholera. Impact and implementation outcomes, mainly acceptability and cost, followed by adoption, feasibility, and sustainability of rapid tests are being evaluated in the field. Challenges to implementing rapid tests range from cultural to technical and administrative issues. CONCLUSIONS Rapid diagnostic tests for vector-borne and other diseases of poverty are being used in the urban context with demonstrated impact on case detection. However, most evidence comes from malaria rapid diagnostics, with variable results. While rapid tests for tuberculosis and visceral leishmaniasis require further implementation studies, more evidence on performance of current tests or development of new alternatives is needed for dengue, Chagas disease, filariasis, leptospirosis, enteric fever, human African trypanosomiasis, schistosomiasis and cholera.
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Affiliation(s)
- Lyda Osorio
- Epidemiology and Population Health Research Group, School of Public Health, Universidad del Valle, Calle 4B No. 36-00 Edif 118 Escuela de Salud Pública, Universidad del Valle Campus San Fernando, Cali, Colombia
| | - Jonny Alejandro Garcia
- Epidemiology and Population Health Research Group, School of Public Health, Universidad del Valle, Calle 4B No. 36-00 Edif 118 Escuela de Salud Pública, Universidad del Valle Campus San Fernando, Cali, Colombia
- School of Medicine, Universidad del Valle, Cali, Colombia
| | - Luis Gabriel Parra
- Epidemiology and Population Health Research Group, School of Public Health, Universidad del Valle, Calle 4B No. 36-00 Edif 118 Escuela de Salud Pública, Universidad del Valle Campus San Fernando, Cali, Colombia
- School of Medicine, Universidad del Valle, Cali, Colombia
| | - Victor Garcia
- Epidemiology and Population Health Research Group, School of Public Health, Universidad del Valle, Calle 4B No. 36-00 Edif 118 Escuela de Salud Pública, Universidad del Valle Campus San Fernando, Cali, Colombia
| | - Laura Torres
- Epidemiology and Population Health Research Group, School of Public Health, Universidad del Valle, Calle 4B No. 36-00 Edif 118 Escuela de Salud Pública, Universidad del Valle Campus San Fernando, Cali, Colombia
| | - Stéphanie Degroote
- University of Montreal Public Health Research Institute (IRSPUM), Montreal, Canada
| | - Valéry Ridde
- University of Montreal Public Health Research Institute (IRSPUM), Montreal, Canada
- French Institute for Research on Sustainable Development (IRD), Paris Descartes University, Population and Development Center (CEPED), Université Paris Sorbonne Cité, National Institute of Health and Medical Research (INSERM), Health, Vulnerabilities and Gender Relations South (SAGESUD), Paris, France
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Ajibola O, Mshelia MB, Gulumbe BH, Eze AA. Typhoid Fever Diagnosis in Endemic Countries: A Clog in the Wheel of Progress? MEDICINA (KAUNAS, LITHUANIA) 2018; 54:E23. [PMID: 30344254 PMCID: PMC6037256 DOI: 10.3390/medicina54020023] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 04/17/2018] [Accepted: 04/19/2018] [Indexed: 12/27/2022]
Abstract
Typhoid fever causes significant morbidity and mortality in developing countries, with inaccurate estimates in some countries affected, especially those situated in Sub-Saharan Africa. Disease burden assessment is limited by lack of a high degree of sensitivity and specificity by many current rapid diagnostic tests. Some of the new technologies, such as PCR and proteomics, may also be useful but are difficult for low-resource settings to apply as point-of-care diagnostics. Weak laboratory surveillance systems may also contribute to the spread of multidrug resistant Salmonella serovar Typhi across endemic areas. In addition, most typhoid-endemic countries employ serological tests that have low sensitivity and specificity making diagnosis unreliable. Here we review currently available typhoid fever diagnostics, and advances in serodiagnosis of S. Typhi.
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Affiliation(s)
- Olumide Ajibola
- Department of Microbiology, Faculty of Science, Federal University Birnin Kebbi, P.M.B. 1157 Kalgo, Kebbi State, Nigeria.
| | - Mari B Mshelia
- Department of Microbiology, Faculty of Science, Federal University Birnin Kebbi, P.M.B. 1157 Kalgo, Kebbi State, Nigeria.
| | - Bashar H Gulumbe
- Department of Microbiology, Faculty of Science, Federal University Birnin Kebbi, P.M.B. 1157 Kalgo, Kebbi State, Nigeria.
| | - Anthonius A Eze
- Department of Medical Biochemistry, University of Nigeria, Enugu Campus, Enugu 400241, Nigeria.
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Abstract
BACKGROUND Differentiating both typhoid (Salmonella Typhi) and paratyphoid (Salmonella Paratyphi A) infection from other causes of fever in endemic areas is a diagnostic challenge. Although commercial point-of-care rapid diagnostic tests (RDTs) for enteric fever are available as alternatives to the current reference standard test of blood or bone marrow culture, or to the widely used Widal Test, their diagnostic accuracy is unclear. If accurate, they could potentially replace blood culture as the World Health Organization (WHO)-recommended main diagnostic test for enteric fever. OBJECTIVES To assess the diagnostic accuracy of commercially available rapid diagnostic tests (RDTs) and prototypes for detecting Salmonella Typhi or Paratyphi A infection in symptomatic persons living in endemic areas. SEARCH METHODS We searched the Cochrane Infectious Diseases Group Specialized Register, MEDLINE, Embase, Science Citation Index, IndMED, African Index Medicus, LILACS, ClinicalTrials.gov, and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) up to 4 March 2016. We manually searched WHO reports, and papers from international conferences on Salmonella infections. We also contacted test manufacturers to identify studies. SELECTION CRITERIA We included diagnostic accuracy studies of enteric fever RDTs in patients with fever or with symptoms suggestive of enteric fever living in endemic areas. We classified the reference standard used as either Grade 1 (result from a blood culture and a bone marrow culture) or Grade 2 (result from blood culture and blood polymerase chain reaction, or from blood culture alone). DATA COLLECTION AND ANALYSIS Two review authors independently extracted the test result data. We used a modified QUADAS-2 extraction form to assess methodological quality. We performed a meta-analysis when there were sufficient studies for the test and heterogeneity was reasonable. MAIN RESULTS Thirty-seven studies met the inclusion criteria and included a total of 5080 participants (range 50 to 1732). Enteric fever prevalence rates in the study populations ranged from 1% to 75% (median prevalence 24%, interquartile range (IQR) 11% to 46%). The included studies evaluated 16 different RDTs, and 16 studies compared two or more different RDTs. Only three studies used the Grade 1 reference standard, and only 11 studies recruited unselected febrile patients. Most included studies were from Asia, with five studies from sub-Saharan Africa. All of the RDTs were designed to detect S.Typhi infection only.Most studies evaluated three RDTs and their variants: TUBEX in 14 studies; Typhidot (Typhidot, Typhidot-M, and TyphiRapid-Tr02) in 22 studies; and the Test-It Typhoid immunochromatographic lateral flow assay, and its earlier prototypes (dipstick, latex agglutination) developed by the Royal Tropical Institute, Amsterdam (KIT) in nine studies. Meta-analyses showed an average sensitivity of 78% (95% confidence interval (CI) 71% to 85%) and specificity of 87% (95% CI 82% to 91%) for TUBEX; and an average sensitivity of 69% (95% CI 59% to 78%) and specificity of 90% (95% CI 78% to 93%) for all Test-It Typhoid and prototype tests (KIT). Across all forms of the Typhidot test, the average sensitivity was 84% (95% CI 73% to 91%) and specificity was 79% (95% CI 70% to 87%). When we based the analysis on the 13 studies of the Typhidot test that either reported indeterminate test results or where the test format means there are no indeterminate results, the average sensitivity was 78% (95% CI 65% to 87%) and specificity was 77% (95% CI 66% to 86%). We did not identify any difference in either sensitivity or specificity between TUBEX, Typhidot, and Test-it Typhoid tests when based on comparison to the 13 Typhidot studies where indeterminate results are either reported or not applicable. If TUBEX and Test-it Typhoid are compared to all Typhidot studies, the sensitivity of Typhidot was higher than Test-it Typhoid (15% (95% CI 2% to 28%), but other comparisons did not show a difference at the 95% level of CIs.In a hypothetical cohort of 1000 patients presenting with fever where 30% (300 patients) have enteric fever, on average Typhidot tests reporting indeterminate results or where tests do not produce indeterminate results will miss the diagnosis in 66 patients with enteric fever, TUBEX will miss 66, and Test-It Typhoid and prototype (KIT) tests will miss 93. In the 700 people without enteric fever, the number of people incorrectly diagnosed with enteric fever would be 161 with Typhidot tests, 91 with TUBEX, and 70 with Test-It Typhoid and prototype (KIT) tests. The CIs around these estimates were wide, with no difference in false positive results shown between tests.The quality of the data for each study was evaluated using a standardized checklist called QUADAS-2. Overall, the certainty of the evidence in the studies that evaluated enteric fever RDTs was low. AUTHORS' CONCLUSIONS In 37 studies that evaluated the diagnostic accuracy of RDTs for enteric fever, few studies were at a low risk of bias. The three main RDT tests and variants had moderate diagnostic accuracy. There was no evidence of a difference between the average sensitivity and specificity of the three main RDT tests. More robust evaluations of alternative RDTs for enteric fever are needed.
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Affiliation(s)
- Lalith Wijedoru
- Liverpool School of Tropical MedicineDepartment of Clinical SciencesLiverpoolUKL3 5QA
| | - Sue Mallett
- University of BirminghamInstitute of Applied Health SciencesEdgbastonBirminghamUKB15 2TT
| | - Christopher M Parry
- Liverpool School of Tropical MedicineDepartment of Clinical SciencesLiverpoolUKL3 5QA
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Storey HL, Huang Y, Crudder C, Golden A, de los Santos T, Hawkins K. A Meta-Analysis of Typhoid Diagnostic Accuracy Studies: A Recommendation to Adopt a Standardized Composite Reference. PLoS One 2015; 10:e0142364. [PMID: 26566275 PMCID: PMC4643909 DOI: 10.1371/journal.pone.0142364] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 10/21/2015] [Indexed: 01/09/2023] Open
Abstract
Novel typhoid diagnostics currently under development have the potential to improve clinical care, surveillance, and the disease burden estimates that support vaccine introduction. Blood culture is most often used as the reference method to evaluate the accuracy of new typhoid tests; however, it is recognized to be an imperfect gold standard. If no single gold standard test exists, use of a composite reference standard (CRS) can improve estimation of diagnostic accuracy. Numerous studies have used a CRS to evaluate new typhoid diagnostics; however, there is no consensus on an appropriate CRS. In order to evaluate existing tests for use as a reference test or inclusion in a CRS, we performed a systematic review of the typhoid literature to include all index/reference test combinations observed. We described the landscape of comparisons performed, showed results of a meta-analysis on the accuracy of the more common combinations, and evaluated sources of variability based on study quality. This wide-ranging meta-analysis suggests that no single test has sufficiently good performance but some existing diagnostics may be useful as part of a CRS. Additionally, based on findings from the meta-analysis and a constructed numerical example demonstrating the use of CRS, we proposed necessary criteria and potential components of a typhoid CRS to guide future recommendations. Agreement and adoption by all investigators of a standardized CRS is requisite, and would improve comparison of new diagnostics across independent studies, leading to the identification of a better reference test and improved confidence in prevalence estimates.
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Affiliation(s)
- Helen L. Storey
- Diagnostics Program, PATH, Seattle, Washington, United States of America
- * E-mail:
| | - Ying Huang
- Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Chris Crudder
- Diagnostics Program, PATH, Seattle, Washington, United States of America
| | - Allison Golden
- Diagnostics Program, PATH, Seattle, Washington, United States of America
| | - Tala de los Santos
- Diagnostics Program, PATH, Seattle, Washington, United States of America
| | - Kenneth Hawkins
- Diagnostics Program, PATH, Seattle, Washington, United States of America
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Khanna A, Khanna M, Gill KS. Comparative Evaluation of Tubex TF (Inhibition Magnetic Binding Immunoassay) for Typhoid Fever in Endemic Area. J Clin Diagn Res 2015; 9:DC14-7. [PMID: 26676104 PMCID: PMC4668408 DOI: 10.7860/jcdr/2015/15459.6810] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 09/21/2015] [Indexed: 11/24/2022]
Abstract
BACKGROUND Typhoid fever remains a significant health problem in endemic countries like India. Various serological tests for the diagnosis of typhoid fever are available commercially. We assessed the usefulness of rapid test based on magnetic particle separation to detect Immunoglobulin against Salmonella typhi O9 lipopolysaccharide. AIM Aim of this study was to compare the sensitivity and specificity of widal test, typhidot and tubex TF test for the diagnosis of typhoid fever in an endemic country like India. MATERIALS AND METHODS Serum samples collected from 50 patients of typhoid fever, 50 patients of non typhoid fever and 100 normal healthy individuals residing in Amritsar were subjected to widal test, typhidot test and tubex TF test as per manufacturer's instructions. Data collected was assessed to find sensitivity and specificity of these tests in an endemic area. RESULTS Significant widal test results were found positive in 68% of patients of typhoid fever and only 4% of non typhoid fever patients. Typhidot (IgM or IgG) was positive in 72% of typhoid fever patients and 10% and 6% in non typhoid fever and normal healthy individuals respectively. Tubex TF showed higher sensitivity of 76% and specificity of 96-99% which was higher than typhidot and comparable to widal test. CONCLUSION This was the first evaluation of rapid tubex TF test in northern India. In countries which can afford high cost of test, tubex TF should be recommended for the diagnosis in acute stage of the disease in clinical setting. However, there is urgent need for a highly specific and sensitive test for the diagnosis of typhoid fever in clinical settings in endemic areas.
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Affiliation(s)
- Ashish Khanna
- Associate Professor, Department of Microbiology, Sri Guru Ram Das Institute of Medical Sciences and Research, Punjab, India
| | - Menka Khanna
- Professor, Department of Pathology, Sri Guru Ram Das Institute of Medical Sciences and Research, Punjab, India
| | - Karamjit Singh Gill
- Professor, Department of Pathology, Sri Guru Ram Das Institute of Medical Sciences and Research and Consultant Nijjer labs and Diagnostic Centre, Punjab, India
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Crump JA, Sjölund-Karlsson M, Gordon MA, Parry CM. Epidemiology, Clinical Presentation, Laboratory Diagnosis, Antimicrobial Resistance, and Antimicrobial Management of Invasive Salmonella Infections. Clin Microbiol Rev 2015; 28:901-37. [PMID: 26180063 PMCID: PMC4503790 DOI: 10.1128/cmr.00002-15] [Citation(s) in RCA: 659] [Impact Index Per Article: 73.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Salmonella enterica infections are common causes of bloodstream infection in low-resource areas, where they may be difficult to distinguish from other febrile illnesses and may be associated with a high case fatality ratio. Microbiologic culture of blood or bone marrow remains the mainstay of laboratory diagnosis. Antimicrobial resistance has emerged in Salmonella enterica, initially to the traditional first-line drugs chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole. Decreased fluoroquinolone susceptibility and then fluoroquinolone resistance have developed in association with chromosomal mutations in the quinolone resistance-determining region of genes encoding DNA gyrase and topoisomerase IV and also by plasmid-mediated resistance mechanisms. Resistance to extended-spectrum cephalosporins has occurred more often in nontyphoidal than in typhoidal Salmonella strains. Azithromycin is effective for the management of uncomplicated typhoid fever and may serve as an alternative oral drug in areas where fluoroquinolone resistance is common. In 2013, CLSI lowered the ciprofloxacin susceptibility breakpoints to account for accumulating clinical, microbiologic, and pharmacokinetic-pharmacodynamic data suggesting that revision was needed for contemporary invasive Salmonella infections. Newly established CLSI guidelines for azithromycin and Salmonella enterica serovar Typhi were published in CLSI document M100 in 2015.
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Affiliation(s)
- John A Crump
- Centre for International Health, University of Otago, Dunedin, Otago, New Zealand Division of Foodborne, Waterborne, and Environmental Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Maria Sjölund-Karlsson
- Division of Foodborne, Waterborne, and Environmental Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Melita A Gordon
- Department of Clinical Infection, Microbiology and Immunology, Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | - Christopher M Parry
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan Department of Clinical Research, London School of Hygiene and Tropical Medicine, London, United Kingdom Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
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9
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Qamar FN, Azmatullah A, Bhutta ZA. Challenges in measuring complications and death due to invasive Salmonella infections. Vaccine 2015; 33 Suppl 3:C16-20. [PMID: 25921727 DOI: 10.1016/j.vaccine.2015.03.103] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 03/26/2015] [Accepted: 03/28/2015] [Indexed: 01/08/2023]
Abstract
Despite the highest burden of Typhoid fever in children globally, exact estimates of morbidity and mortality are lacking due to scarcity of published data. Despite a high prevalence and a socioeconomic burden in developing countries, published data with morbidity and mortality figures are limited especially Africa and South American regions. Data from the community is insufficient and most case fatality estimates are extrapolations from hospital based studies that do not cover all geographical regions, and include cases which may or not be culture confirmed, MDR resistant or sensitive cases, or from mixed populations of age (adults and children). Complications of typhoid such as intestinal perforation, bone marrow suppression, and encephalopathy are dependent on MDR/Fluoroquinolone resistant Salmonella infection, comorbidities such as malnutrition, and health-care access. Data is again insufficient to estimate the true burden of Typhoid Fever in different regions and groups of populations. Although there has been a rapid decline in cases in developed countries with the advent of improved sanitization, timely and easy access to health care and laboratories, this is still not the case in the developing countries where Typhoid deaths are still occurring. The way forward is to develop rapid and cost effective point of care diagnostic tests, put in place validated clinical algorithms for suspected clinical cases, and design prospective, and community based studies in different groups, implement maintenance of electronic health records in large public sector hospitals and regions to identify populations that will benefit most from the implementation of vaccine. Policies on public health education and typhoid vaccine may help to reduce morbidity and mortality due to the disease.
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Affiliation(s)
- Farah Naz Qamar
- Department of Pediatrics and Child Health, Center of Excellence in Women and Child Health, The Aga Khan University, PO Box 3500, Karachi 74800, Pakistan.
| | - Asma Azmatullah
- Department of Pediatrics and Child Health, Center of Excellence in Women and Child Health, The Aga Khan University, PO Box 3500, Karachi 74800, Pakistan
| | - Zulfiqar A Bhutta
- Department of Pediatrics and Child Health, Center of Excellence in Women and Child Health, The Aga Khan University, PO Box 3500, Karachi 74800, Pakistan.
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10
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Fan F, Du P, Kan B, Yan M. The Development and Evaluation of a Loop-Mediated Isothermal Amplification Method for the Rapid Detection of Salmonella enterica serovar Typhi. PLoS One 2015; 10:e0124507. [PMID: 25910059 PMCID: PMC4409374 DOI: 10.1371/journal.pone.0124507] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 03/03/2015] [Indexed: 11/24/2022] Open
Abstract
Typhoid fever remains a public health threat in many countries. A positive result in traditional culture is a gold-standard for typhoid diagnosis, but this method is time consuming and not sensitive enough for detection of samples containing a low copy number of the target organism. The availability of the loop-mediated isothermal amplification (LAMP) assay, which offers high speed and simplicity in detection of specific targets, has vastly improved the diagnosis of numerous infectious diseases. However, little research efforts have been made on utilizing this approach for diagnosis of Salmonella enterica serovar Typhi by targeting a single and specific gene. In this study, a LAMP assay for rapid detection of S. Typhi based on a novel marker gene, termed STY2879-LAMP, was established and evaluated with real-time PCR (RT-PCR). The specificity tests showed that STY2879 could be amplified in all S. Typhi strains isolated in different years and regions in China, whereas no amplification was observable in non-typhoidal strains covering 34 Salmonella serotypes and other pathogens causing febrile illness. The detection limit of STY2879-LAMP for S. Typhi was 15 copies/reaction in reference plasmids, 200 CFU/g with simple heat-treatment of DNA extracted from simulated stool samples and 20 CFU/ml with DNA extracted from simulated blood samples, which was 10 fold more sensitive than the parallel RT-PCR control experiment. Furthermore, the sensitivity of STY2879-LAMP and RT-PCR combining the traditional culture enrichment method for simulated stool and blood spiked with lower S. Typhi count during the 10 h enrichment time was also determined. In comparison with LAMP, the positive reaction time for RT-PCR required additional 2-3 h enrichment time for either simulated stool or blood specimens. Therefore, STY2879-LAMP is of practical value in the clinical settings and has a good potential for application in developing regions due to its easy-to-use protocol.
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Affiliation(s)
- Fenxia Fan
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang, China
| | - Pengcheng Du
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang, China
| | - Biao Kan
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang, China
- * E-mail: (MY); (BK)
| | - Meiying Yan
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, Zhejiang, China
- * E-mail: (MY); (BK)
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Arndt MB, Mosites EM, Tian M, Forouzanfar MH, Mokhdad AH, Meller M, Ochiai RL, Walson JL. Estimating the burden of paratyphoid a in Asia and Africa. PLoS Negl Trop Dis 2014; 8:e2925. [PMID: 24901439 PMCID: PMC4046978 DOI: 10.1371/journal.pntd.0002925] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 04/19/2014] [Indexed: 11/18/2022] Open
Abstract
Despite the increasing availability of typhoid vaccine in many regions, global estimates of mortality attributable to enteric fever appear stable. While both Salmonella enterica serovar Typhi (S. Typhi) and serovar Paratyphi (S. Paratyphi) cause enteric fever, limited data exist estimating the burden of S. Paratyphi, particularly in Asia and Africa. We performed a systematic review of both English and Chinese-language databases to estimate the regional burden of paratyphoid within Africa and Asia. Distinct from previous reviews of the topic, we have presented two separate measures of burden; both incidence and proportion of enteric fever attributable to paratyphoid. Included articles reported laboratory-confirmed Salmonella serovar classification, provided clear methods on sampling strategy, defined the age range of participants, and specified the time period of the study. A total of 64 full-text articles satisfied inclusion criteria and were included in the qualitative synthesis. Paratyphoid A was commonly identified as a cause of enteric fever throughout Asia. The highest incidence estimates in Asia came from China; four studies estimated incidence rates of over 150 cases/100,000 person-years. Paratyphoid A burden estimates from Africa were extremely limited and with the exception of Nigeria, few population or hospital-based studies from Africa reported significant Paratyphoid A burden. While significant gaps exist in the existing population-level estimates of paratyphoid burden in Asia and Africa, available data suggest that paratyphoid A is a significant cause of enteric fever in Asia. The high variability in documented incidence and proportion estimates of paratyphoid suggest considerable geospatial variability in the burden of paratyphoid fever. Additional efforts to monitor enteric fever at the population level will be necessary in order to accurately quantify the public health threat posed by S. Paratyphi A, and to improve the prevention and treatment of enteric fever. Enteric fever due to Salmonella enterica serovar Typhi (S. Typhi) and serovar Paratyphi (S. Paratyphi A, B, C) remains a global public health concern. While numerous studies have estimated the levels or burden of S. Typhi, there are only limited data estimating the burden of S. Paratyphi A, particularly in Asia and Africa. We reviewed both English and Chinese-language databases for estimates of the regional burden within Africa and Asia, including new paratyphoid A cases/year and proportion of enteric fever cases attributable to paratyphoid A. S. Paratyphi A appears to constitute a significant proportion of all cases of enteric fever in Asia, though population level estimates are limited, especially in Africa. There was high variability in reported paratyphoid A burden estimates, which suggests considerable geospatial variability in the burden of paratyphoid fever. Improved efforts to monitor enteric fever at the population level are warranted in order to correctly measure the public health threat posed by S. Paratyphi A and to determine the potential need for S. Paratyphi specific prevention and treatment interventions.
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Affiliation(s)
- Michael B. Arndt
- Department of Epidemiology, University of Washington, Seattle, Washington, United States of America
- * E-mail:
| | - Emily M. Mosites
- Department of Epidemiology, University of Washington, Seattle, Washington, United States of America
| | - Mu Tian
- Department of Health Services, University of Washington, Seattle, Washington, United States of America
| | | | - Ali H. Mokhdad
- Department of Epidemiology, University of Washington, Seattle, Washington, United States of America
- Department of Health Services, University of Washington, Seattle, Washington, United States of America
- Institute for Health Metrics and Evaluation, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
| | - Margaret Meller
- The Bill and Melinda Gates Foundation, Seattle, Washington, United States of America
| | | | - Judd L. Walson
- Department of Epidemiology, University of Washington, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
- Department of Pediatrics, University of Washington, Seattle, Washington, United States of America
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Parry CM, Wijedoru L, Arjyal A, Baker S. The utility of diagnostic tests for enteric fever in endemic locations. Expert Rev Anti Infect Ther 2014; 9:711-25. [DOI: 10.1586/eri.11.47] [Citation(s) in RCA: 118] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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13
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Sankar S, Vadivel K, Nandagopal B, Jesudason MV, Sridharan G. A multiplex nested PCR for the simultaneous detection of Salmonella typhi, Mycobacterium tuberculosis, and Burkholderia pseudomallei in patients with pyrexia of unknown origin (PUO) in Vellore, South India. Mol Diagn Ther 2014; 18:315-21. [PMID: 24385404 DOI: 10.1007/s40291-013-0079-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
BACKGROUND AND OBJECTIVES Salmonella typhi, Mycobacterium tuberculosis, and Burkholderia pseudomallei are among the most important monocyte-tropic bacterial agents causing pyrexia of unknown origin (PUO), with a significant number of endemic infections in both South and Southeast Asian regions. These infections pose a major risk to travelers to these regions as well. METHODS We developed and evaluated a multiplex nested polymerase chain reaction (PCR) for the simultaneous detection of the three pathogens in 305 patients' buffy coat samples. RESULTS The assay for S. typhi and B. pseudomallei was able to detect down to 1 colony forming unit/5 μL PCR input and M. tuberculosis was detected down to 20 genome copies/5 μL PCR input. S. typhi was detected in 10 (3.3 %) individuals, B. pseudomallei in 10 individuals (3.3 %), and M. tuberculosis in 18 individuals (5.9 %). Co-infections of M. tuberculosis and B. pseudomallei were detected in three individuals and S. typhi and B. pseudomallei in two individuals. CONCLUSION This protocol is efficient for PUO diagnosis especially in Asian countries.
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Affiliation(s)
- Sathish Sankar
- Sri Sakthi Amma Institute of Biomedical Research, Sri Narayani Hospital and Research Centre, Sripuram, Vellore, 632 055, Tamil Nadu, India,
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Thriemer K, Ley B, Menten J, Jacobs J, van den Ende J. A systematic review and meta-analysis of the performance of two point of care typhoid fever tests, Tubex TF and Typhidot, in endemic countries. PLoS One 2013; 8:e81263. [PMID: 24358109 PMCID: PMC3864786 DOI: 10.1371/journal.pone.0081263] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Accepted: 10/10/2013] [Indexed: 11/26/2022] Open
Abstract
Background In the absence of well-equipped laboratory infrastructure in many developing countries the accurate diagnosis of typhoid fever is challenging. Rapid diagnostic tests (RDT) with good performance indicators would be helpful to improve clinical management of suspected cases. We performed a systematic literature review and meta- analysis to determine the performance of TUBEX TF and Typhidot for the diagnosis of typhoid fever using PRISMA guidelines. Methods Titles and abstracts were reviewed for relevance. Articles were screened for language, reference method and completeness. Studies were categorized according to control groups used. Meta-analysis was performed only for categories where enough data was available to combine sensitivity and specificity estimates. Sub-analysis was performed for the Typhidot test to determine the influence of indeterminate results on test performance. Results A total of seven studies per test were included. The sensitivity of TUBEX TF ranged between 56% and 95%, Specificity between 72% and 95%. Meta-analysis showed an average sensitivity of 69% (95%CI: 45–85) and an average specificity of 88% (CI95%:83–91). A formal meta-analysis for Typhidot was not possible due to limited data available. Across the extracted studies, sensitivity and specificity estimates ranged from 56% to 84% and 31% to 97% respectively. Conclusion The observed performance does not support the use of either rapid diagnostic test exclusively as the basis for diagnosis and treatment. There is a need to develop an RDT for typhoid fever that has a performance level comparable to malaria RDTs.
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Affiliation(s)
- Kamala Thriemer
- Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
- * E-mail:
| | - Benedikt Ley
- Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Joris Menten
- Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Jan Jacobs
- Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Jef van den Ende
- Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
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Das S, Rajendran K, Dutta P, Saha TK, Dutta S. Validation of a new serology-based dipstick test for rapid diagnosis of typhoid fever. Diagn Microbiol Infect Dis 2013; 76:5-9. [PMID: 23420012 DOI: 10.1016/j.diagmicrobio.2013.01.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 01/09/2013] [Accepted: 01/16/2013] [Indexed: 10/27/2022]
Abstract
Currently, no reliable diagnostic test is available for typhoid fever. One serology-based dipstick test, developed indigenously, was validated in this study. Preserved sera from 336 fever patients with known culture results for Salmonella Typhi were blindly tested by the Widal test and the new assay. Analytical sensitivities, specificities, and efficiencies for the new assay versus the Widal test were 68.8% versus 62.5%, 71.1% versus 37.1%, and 70.5% versus 43.2%, respectively (p < 0.001), considering S. Typhi-positive samples as gold standards. Thereafter, fresh sera from 102 hospital-attending children with clinical typhoid fever (including 20 confirmed nontyphoidal cases as control) were tested by both methods and analyzed statistically. The diagnostic sensitivity, specificity, and efficiency were 51.2%, 85%, and 57.8% for the new assay, and 43.9%, 65%, and 48% for the Widal test, respectively. Overall performance ability of the new assay was not better than the Widal test (p > 0.5). Further improvement of the new point-of-care typhoid assay is recommended before implementation in the field setup.
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Affiliation(s)
- Surojit Das
- Division of Bacteriology and Clinical Medicine, National Institute of Cholera and Enteric Diseases, Kolkata, India
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Affiliation(s)
- Bhavna Dhingra
- Department of Pediatrics, Maulana Azad Medical College, and Associated Chacha Nehru Bal Chikitsalaya and Lok Nayak Hospital, New Delhi, India.
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Ley B, Thriemer K, Ame SM, Mtove GM, von Seidlein L, Amos B, Hendriksen ICE, Mwambuli A, Shoo A, Kim DR, Ochiai LR, Favorov M, Clemens JD, Wilfing H, Deen JL, Ali SM. Assessment and comparative analysis of a rapid diagnostic test (Tubex®) for the diagnosis of typhoid fever among hospitalized children in rural Tanzania. BMC Infect Dis 2011; 11:147. [PMID: 21609455 PMCID: PMC3123569 DOI: 10.1186/1471-2334-11-147] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Accepted: 05/24/2011] [Indexed: 11/16/2022] Open
Abstract
Background Typhoid fever remains a significant health problem in many developing countries. A rapid test with a performance comparable to that of blood culture would be highly useful. A rapid diagnostic test for typhoid fever, Tubex®, is commercially available that uses particle separation to detect immunoglobulin M directed towards Salmonella Typhi O9 lipopolysaccharide in sera. Methods We assessed the sensitivity and specificity of the Tubex test among Tanzanian children hospitalized with febrile illness using blood culture as gold standard. Evaluation was done considering blood culture confirmed S. Typhi with non-typhi salmonella (NTS) and non - salmonella isolates as controls as well as with non-salmonella isolates only. Results Of 139 samples tested with Tubex, 33 were positive for S. Typhi in blood culture, 49 were culture-confirmed NTS infections, and 57 were other non-salmonella infections. Thirteen hemolyzed samples were excluded. Using all non - S. Typhi isolates as controls, we showed a sensitivity of 79% and a specificity of 89%. When the analysis was repeated excluding NTS from the pool of controls we showed a sensitivity of 79% and a specificity of 97%. There was no significant difference in the test performance using the two different control groups (p > 0.05). Conclusion This first evaluation of the Tubex test in an African setting showed a similar performance to those seen in some Asian settings. Comparison with the earlier results of a Widal test using the same samples showed no significant difference (p > 0.05) for any of the performance indicators, irrespective of the applied control group.
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Affiliation(s)
- Benedikt Ley
- Translational Research Division, International Vaccine Institute, Seoul, Korea.
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Ley B, Mtove G, Thriemer K, Amos B, von Seidlein L, Hendriksen I, Mwambuli A, Shoo A, Malahiyo R, Ame SM, Kim DR, Ochiai LR, Clemens JD, Reyburn H, Wilfing H, Magesa S, Deen JL. Evaluation of the Widal tube agglutination test for the diagnosis of typhoid fever among children admitted to a rural hdospital in Tanzania and a comparison with previous studies. BMC Infect Dis 2010; 10:180. [PMID: 20565990 PMCID: PMC2898821 DOI: 10.1186/1471-2334-10-180] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Accepted: 06/22/2010] [Indexed: 11/16/2022] Open
Abstract
Background The diagnosis of typhoid fever is confirmed by culture of Salmonella enterica serotype Typhi (S. typhi). However, a more rapid, simpler, and cheaper diagnostic method would be very useful especially in developing countries. The Widal test is widely used in Africa but little information exists about its reliability. Methods We assessed the performance of the Widal tube agglutination test among febrile hospitalized Tanzanian children. We calculated the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of various anti-TH and -TO titers using culture-confirmed typhoid fever cases as the "true positives" and all other febrile children with blood culture negative for S. typhi as the "true negatives." Results We found that 16 (1%) of 1,680 children had culture-proven typhoid fever. A single anti-TH titer of 1:80 and higher was the optimal indicator of typhoid fever. This had a sensitivity of 75%, specificity of 98%, NPV of 100%, but PPV was only 26%. We compared our main findings with those from previous studies. Conclusion Among febrile hospitalized Tanzanian children with a low prevalence of typhoid fever, a Widal titer of ≥ 1:80 performed well in terms of sensitivity, specificity, and NPV. However a test with improved PPV that is similarly easy to apply and cost-efficient is desirable.
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Clinical value of Tubex and Typhidot rapid diagnostic tests for typhoid fever in an urban community clinic in Bangladesh. Diagn Microbiol Infect Dis 2008; 61:381-6. [PMID: 18501549 DOI: 10.1016/j.diagmicrobio.2008.03.018] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2007] [Revised: 03/25/2008] [Accepted: 03/28/2008] [Indexed: 11/20/2022]
Abstract
Tubex and Typhidot, rapid tests for typhoid fever, performed well in evaluations conducted in hospital settings among patients with culture-confirmed typhoid fever. We evaluated these tests in a community clinic in Bangladesh. Blood samples were obtained from 867 febrile patients for culture, Typhidot and Tubex tests. Considering the 43 blood culture-confirmed cases of typhoid fever as typhoid positive and the 24 other confirmed bacteremia cases as typhoid negative, Tubex was 60% sensitive and 58% specific, with 90% positive and 58% negative predictive values (NPVs); Typhidot was 67% sensitive and 54% specific, with 85% positive and 81% NPVs. When blood culture-negative patients and other bacteremia cases together were considered typhoid negative, positive predictive values were only 14% for Tubex and 13% for Typhidot, increasing to only 38% and 20% when restricted to patients with > or = 7 days of fever. We conclude that the value of Tubex and Typhidot tests for typhoid fever diagnosis in a community clinic in urban Bangladesh is low.
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