151
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Cost-effectiveness of using environmental surveillance to target the roll-out typhoid conjugate vaccine. Vaccine 2020; 38:1661-1670. [PMID: 31917040 DOI: 10.1016/j.vaccine.2019.12.061] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 12/26/2019] [Accepted: 12/27/2019] [Indexed: 01/15/2023]
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152
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Rothe C, Boecken G. Reiseimpfungen. Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz 2020; 63:74-84. [DOI: 10.1007/s00103-019-03064-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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153
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Raymond M, Gibani MM, Day NPJ, Cheah PY. Typhoidal Salmonella human challenge studies: ethical and practical challenges and considerations for low-resource settings. Trials 2019; 20:704. [PMID: 31852488 PMCID: PMC6921376 DOI: 10.1186/s13063-019-3844-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Typhoidal Salmonella is a major global problem affecting more than 12 million people annually. Controlled human infection models (CHIMs) in high-resource settings have had an important role in accelerating the development of conjugate vaccines against Salmonella Typhi. The typhoidal Salmonella model has an established safety profile in over 2000 volunteers in high-income settings, and trial protocols, with modification, could be readily transferred to new study sites. To date, a typhoidal Salmonella CHIM has not been conducted in a low-resource setting, although it is being considered. Our article describes the challenges posed by a typhoidal Salmonella CHIM in the high-resource setting of Oxford and explores considerations for an endemic setting. Development of CHIMs in endemic settings is scientifically justifiable as it remains unclear whether findings from challenge studies performed in high-resource non-endemic settings can be extrapolated to endemic settings, where the burden of invasive Salmonella is highest. Volunteers are likely to differ across a range of important variables such as previous Salmonella exposure, diet, intestinal microbiota, and genetic profile. CHIMs in endemic settings arguably are ethically justifiable as affected communities are more likely to gain benefit from the study. Local training and research capacity may be bolstered. Safety was of primary importance in the Oxford model. Risk of harm to the individual was mitigated by careful inclusion and exclusion criteria; close monitoring with online diary and daily visits; 24/7 on-call staffing; and access to appropriate hospital facilities with capacity for in-patient admission. Risk of harm to the community was mitigated by exclusion of participants with contact with vulnerable persons; stringent hygiene and sanitation precautions; and demonstration of clearance of Salmonella infection from stool following antibiotic treatment. Safety measures should be more stringent in settings where health systems, transport networks, and sanitation are less robust. We compare the following issues between high- and low-resource settings: scientific justification, risk of harm to the individual and community, benefits to the individual and community, participant understanding, compensation, and regulatory requirements. We conclude that, with careful consideration of country-specific ethical and practical issues, a typhoidal Salmonella CHIM in an endemic setting is possible.
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Affiliation(s)
- Meriel Raymond
- Oxford Vaccine Group Centre for Clinical Vaccinology and Tropical Medicine (CCVTM), Churchill Hospital, Old Road, Headington, Oxford, OX3 7LE, UK
| | - Malick M Gibani
- Oxford Vaccine Group Centre for Clinical Vaccinology and Tropical Medicine (CCVTM), Churchill Hospital, Old Road, Headington, Oxford, OX3 7LE, UK
| | - Nicholas P J Day
- Mahidol Oxford Tropical Medicine Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Bangkok, 10400, Thailand.,Nuffield Department of Clinical Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7FZ, UK
| | - Phaik Yeong Cheah
- Mahidol Oxford Tropical Medicine Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Bangkok, 10400, Thailand. .,Nuffield Department of Clinical Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7FZ, UK. .,Nuffield Departmemt of Population Health, The Ethox Centere, University of Oxford, Old Road, Oxford, OX3 7LF, UK.
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154
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MacLennan CA, Aguilar AO, Steele AD. Consensus Report on Shigella Controlled Human Infection Model: Introduction and Overview. Clin Infect Dis 2019; 69:S577-S579. [PMID: 31816066 PMCID: PMC6901124 DOI: 10.1093/cid/ciz886] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In recent years, controlled human infection models (CHIMs) have become available for a range of infectious agents and have proved invaluable for understanding the disease process, pathogenesis, and mechanisms of immunity. CHIM studies have also contributed significantly to advancing development of a number of vaccines by providing an indication of vaccine efficacy. The Shigella CHIM has been established in 3 sites in the United States, and it is likely that the CHIM will play an important regulatory role for advancing the range of Shigella vaccine candidates that are currently in development. This supplement describes the harmonization of best practices across sites, with a view to maximizing the contribution that CHIM studies can make to Shigella vaccine development.
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155
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Talaat KR, Bourgeois AL, Frenck RW, Chen WH, MacLennan CA, Riddle MS, Suvarnapunya AE, Brubaker JL, Kotloff KL, Porter CK. Consensus Report on Shigella Controlled Human Infection Model: Conduct of Studies. Clin Infect Dis 2019; 69:S580-S590. [PMID: 31816068 PMCID: PMC6901126 DOI: 10.1093/cid/ciz892] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Shigella causes morbidity and mortality worldwide, primarily affecting young children living in low-resource settings. It is also of great concern due to increasing antibiotic resistance, and is a priority organism for the World Health Organization. A Shigella vaccine would decrease the morbidity and mortality associated with shigellosis, improve child health, and decrease the need for antibiotics. Controlled human infection models (CHIMs) are useful tools in vaccine evaluation for early up- or down-selection of vaccine candidates and potentially useful in support of licensure. Over time, the methods employed in these models have become more uniform across sites performing CHIM trials, although some differences in conduct persist. In November 2017, a Shigella CHIM workshop was convened in Washington, District of Columbia. Investigators met to discuss multiple aspects of these studies, including study procedures, clinical and immunological endpoints, and shared experiences. This article serves as a uniform procedure by which to conduct Shigella CHIM studies.
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Affiliation(s)
- Kawsar R Talaat
- Center for Immunization Research, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | | | - Robert W Frenck
- Division of Infectious Diseases, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Wilbur H Chen
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore
| | | | - Mark S Riddle
- F. Edward Hébert School of Medicine, Uniformed Services University, Bethesda
| | - Akamol E Suvarnapunya
- Department of Enteric Infections, Bacterial Diseases Branch, Walter Reed Army Institute of Research, Silver Spring
| | - Jessica L Brubaker
- Global Disease Epidemiology and Control Program, Department of International Health, Johns Hopkins Bloomberg School of Public Health
| | - Karen L Kotloff
- Division of Infectious Disease and Tropical Pediatrics, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore
| | - Chad K Porter
- Enteric Disease Department, Naval Medical Research Center, Silver Spring, Maryland
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156
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Thakur R, Pathania P, Kaur N, Joshi V, Kondepudi KK, Suri CR, Rishi P. Prophylactic potential of cytolethal distending toxin B (CdtB) subunit of typhoid toxin against Typhoid fever. Sci Rep 2019; 9:18404. [PMID: 31804525 PMCID: PMC6895121 DOI: 10.1038/s41598-019-54690-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 11/18/2019] [Indexed: 02/04/2023] Open
Abstract
Typhoid fever caused by Salmonella enterica serovar Typhi (S.Typhi) continues to be a major problem, especially in developing countries. Due to the rapid emergence of multi-drug-resistant (MDR) strains, which limits the efficacy of conventional antibiotics as well as problems associated with the existing vaccines, efforts are being made to develop effective prophylactic agents. CdtB subunit of typhoid toxin was selected for assessing its vaccine potential due to its high conservation throughout the Typhi strains. In-vitro assessment of DNase activity of cloned and purified CdtB protein showed a significant decrease in the band intensity of DNA. The measure of metabolic activity and morphological alterations assessed using different cell lines in the presence of CdtB protein showed no significant signs of toxicity. These observations were further strengthened by cell cycle analysis, assessed by flow cytometry. Keeping these observations in mind, the immunoprotective potential of CdtB was assessed using S.Typhi induced mouse peritonitis model. A significant titer of IgG antibodies (>128000) against CdtB protein was recorded in the immunized mice by enzyme-linked immunosorbent assay (ELISA), which was also validated by immunoblotting. Active immunization with the protein protected 75% mice against a lethal dose of S.Typhi Ty2. The data indicated a significant (up to 5 log) reduction in the bacterial load in the spleen and liver of immunized-infected mice compared to control (unimmunized-infected) mice which might have resulted in the modulation of histoarchitecture of spleen and liver and the levels of cytokines (IL-6, TNF-α and IL-10) production; thereby indicating the effectiveness of the subunit. The observations deduced from the study give the proof of concept of immunogenic potential of protein. However, further studies involving the immunoreactivity of CdtB with the statistically significant number of sera samples obtained from the human patients would be helpful in establishing the relevance of CdtB protein in humans and for making the strategies to develop it as an effective vaccine candidate.
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Affiliation(s)
- Reena Thakur
- Department of Microbiology, Panjab University, Chandigarh, India
| | - Preeti Pathania
- Department of Microbiology, Panjab University, Chandigarh, India
| | - Navneet Kaur
- Department of Microbiology, Panjab University, Chandigarh, India
| | - Vattan Joshi
- Department of Microbiology, Panjab University, Chandigarh, India
| | | | | | - Praveen Rishi
- Department of Microbiology, Panjab University, Chandigarh, India.
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157
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Shakya M, Colin-Jones R, Theiss-Nyland K, Voysey M, Pant D, Smith N, Liu X, Tonks S, Mazur O, Farooq YG, Clarke J, Hill J, Adhikari A, Dongol S, Karkey A, Bajracharya B, Kelly S, Gurung M, Baker S, Neuzil KM, Shrestha S, Basnyat B, Pollard AJ. Phase 3 Efficacy Analysis of a Typhoid Conjugate Vaccine Trial in Nepal. N Engl J Med 2019; 381:2209-2218. [PMID: 31800986 PMCID: PMC6785806 DOI: 10.1056/nejmoa1905047] [Citation(s) in RCA: 128] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Salmonella Typhi is a major cause of fever in children in low- and middle-income countries. A typhoid conjugate vaccine (TCV) that was recently prequalified by the World Health Organization was shown to be efficacious in a human challenge model, but data from efficacy trials in areas where typhoid is endemic are lacking. METHODS In this phase 3, randomized, controlled trial in Lalitpur, Nepal, in which both the participants and observers were unaware of the trial-group assignments, we randomly assigned children who were between 9 months and 16 years of age, in a 1:1 ratio, to receive either a TCV or a capsular group A meningococcal conjugate vaccine (MenA) as a control. The primary outcome was typhoid fever confirmed by blood culture. We present the prespecified analysis of the primary and main secondary outcomes (including an immunogenicity subgroup); the 2-year trial follow-up is ongoing. RESULTS A total of 10,005 participants received the TCV and 10,014 received the MenA vaccine. Blood culture-confirmed typhoid fever occurred in 7 participants who received TCV (79 cases per 100,000 person-years) and in 38 who received MenA vaccine (428 cases per 100,000 person-years) (vaccine efficacy, 81.6%; 95% confidence interval, 58.8 to 91.8; P<0.001). A total of 132 serious adverse events (61 in the TCV group and 71 in the MenA vaccine group) occurred in the first 6 months, and 1 event (pyrexia) was identified as being vaccine-related; the participant remained unaware of the trial-group assignment. Similar rates of adverse events were noted in the two trial groups; fever developed in 5.0% of participants in the TCV group and 5.4% in the MenA vaccine group in the first week after vaccination. In the immunogenicity subgroup, seroconversion (a Vi IgG level that at least quadrupled 28 days after vaccination) was 99% in the TCV group (677 of 683 participants) and 2% in the MenA vaccine group (8 of 380 participants). CONCLUSIONS A single dose of TCV was immunogenic and effective in reducing S. Typhi bacteremia in children 9 months to 16 years of age. (Funded by the Bill and Melinda Gates Foundation; Current Controlled Trials number, ISRCTN43385161.).
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Affiliation(s)
- Mila Shakya
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Rachel Colin-Jones
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Katherine Theiss-Nyland
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Merryn Voysey
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Dikshya Pant
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Nicola Smith
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Xinxue Liu
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Susan Tonks
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Olga Mazur
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Yama G Farooq
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Jenny Clarke
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Jennifer Hill
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Anup Adhikari
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Sabina Dongol
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Abhilasha Karkey
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Binod Bajracharya
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Sarah Kelly
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Meeru Gurung
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Stephen Baker
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Kathleen M Neuzil
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Shrijana Shrestha
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Buddha Basnyat
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
| | - Andrew J Pollard
- From the Oxford University Clinical Research Unit (M.S., S.D., A.K., B. Basnyat), Patan Academy of Health Sciences, Patan Hospital (D.P., M.G., S.S.), the Nepal Family Development Foundation (A.A.), and Wasa Pasa Polyclinics Private, Lalitpur (B. Bajracharya) - all in Kathmandu; the Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford (R.C.-J., K.T.-N., M.V., N.S., X.L., S.T., O.M., Y.G.F., J.C., J.H., S.K., A.J.P.), and the Department of Medicine, University of Cambridge, Cambridge (S.B.) - all in the United Kingdom; the Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam (S.B.); and the University of Maryland School of Medicine, Baltimore (K.M.N.)
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158
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Marks F, Kim JH. Parting the Clouds over Typhoid with a New Conjugate Vaccine. N Engl J Med 2019; 381:2262-2264. [PMID: 31800994 DOI: 10.1056/nejme1914695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Florian Marks
- From the International Vaccine Institute, Seoul, South Korea (F.M., J.H.K.); and the University of Cambridge, Cambridge, United Kingdom (F.M.)
| | - Jerome H Kim
- From the International Vaccine Institute, Seoul, South Korea (F.M., J.H.K.); and the University of Cambridge, Cambridge, United Kingdom (F.M.)
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159
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Jin C, Gibani MM, Pennington SH, Liu X, Ardrey A, Aljayyoussi G, Moore M, Angus B, Parry CM, Biagini GA, Feasey NA, Pollard AJ. Treatment responses to Azithromycin and Ciprofloxacin in uncomplicated Salmonella Typhi infection: A comparison of Clinical and Microbiological Data from a Controlled Human Infection Model. PLoS Negl Trop Dis 2019; 13:e0007955. [PMID: 31877141 PMCID: PMC6948818 DOI: 10.1371/journal.pntd.0007955] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Revised: 01/08/2020] [Accepted: 11/26/2019] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND The treatment of enteric fever is complicated by the emergence of antimicrobial resistant Salmonella Typhi. Azithromycin is commonly used for first-line treatment of uncomplicated enteric fever, but the response to treatment may be sub-optimal in some patient groups when compared with fluoroquinolones. METHODS We performed an analysis of responses to treatment with azithromycin (500mg once-daily, 14 days) or ciprofloxacin (500mg twice-daily, 14 days) in healthy UK volunteers (18-60 years) enrolled into two Salmonella controlled human infection studies. Study A was a single-centre, open-label, randomised trial. Participants were randomised 1:1 to receive open-label oral ciprofloxacin or azithromycin, stratified by vaccine group (Vi-polysaccharide, Vi-conjugate or control Men-ACWY vaccine). Study B was an observational challenge/re-challenge study, where participants were randomised to challenge with Salmonella Typhi or Salmonella Paratyphi A. Outcome measures included fever clearance time, blood-culture clearance time and a composite measure of prolonged treatment response (persistent fever ≥38.0°C for ≥72 hours, persistently positive S. Typhi blood cultures for ≥72 hours, or change in antibiotic treatment). Both trials are registered with ClinicalTrials.gov (NCT02324751 and NCT02192008). FINDINGS In 81 participants diagnosed with S. Typhi in two studies, treatment with azithromycin was associated with prolonged bacteraemia (median 90.8 hours [95% CI: 65.9-93.8] vs. 20.1 hours [95% CI: 7.8-24.3], p<0.001) and prolonged fever clearance times <37.5°C (hazard ratio 2.4 [95%CI: 1.2-5.0]; p = 0.02). Results were consistent when studies were analysed independently and in a sub-group of participants with no history of vaccination or previous challenge. A prolonged treatment response was observed significantly more frequently in the azithromycin group (28/52 [54.9%]) compared with the ciprofloxacin group (1/29 [3.5%]; p<0.001). In participants treated with azithromycin, observed systemic plasma concentrations of azithromycin did not exceed the minimum inhibitory concentration (MIC), whilst predicted intracellular concentrations did exceed the MIC. In participants treated with ciprofloxacin, the observed systemic plasma concentrations and predicted intracellular concentrations of ciprofloxacin exceeded the MIC. INTERPRETATION Azithromycin at a dose of 500mg daily is an effective treatment for fully sensitive strains of S. Typhi but is associated with delayed treatment response and prolonged bacteraemia when compared with ciprofloxacin within the context of a human challenge model. Whilst the cellular accumulation of azithromycin is predicted to be sufficient to treat intracellular S. Typhi, systemic exposure may be sub-optimal for the elimination of extracellular circulating S. Typhi. In an era of increasing antimicrobial resistance, further studies are required to define appropriate azithromycin dosing regimens for enteric fever and to assess novel treatment strategies, including combination therapies. TRIAL REGISTRATION ClinicalTrials.gov (NCT02324751 and NCT02192008).
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Affiliation(s)
- Celina Jin
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Malick M. Gibani
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
- Department of Infectious Diseases, Imperial College London, London, United Kingdom
| | - Shaun H. Pennington
- Research Centre for Drugs and Diagnostics, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Xinxue Liu
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Alison Ardrey
- Research Centre for Drugs and Diagnostics, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Ghaith Aljayyoussi
- Research Centre for Drugs and Diagnostics, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Maria Moore
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Brian Angus
- Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Christopher M. Parry
- Research Centre for Drugs and Diagnostics, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
- Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
- School of Tropical Medicine and Global Health, Nagsaki University, Nagasaki, Japan
| | - Giancarlo A. Biagini
- Research Centre for Drugs and Diagnostics, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Nicholas A. Feasey
- Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
- Malawi Liverpool Wellcome Trust Clinical research Programme, Blantyre, Malawi
| | - Andrew J. Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
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160
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Dahora LC, Jin C, Spreng RL, Feely F, Mathura R, Seaton KE, Zhang L, Hill J, Jones E, Alam SM, Dennison SM, Pollard AJ, Tomaras GD. IgA and IgG1 Specific to Vi Polysaccharide of Salmonella Typhi Correlate With Protection Status in a Typhoid Fever Controlled Human Infection Model. Front Immunol 2019; 10:2582. [PMID: 31781100 PMCID: PMC6852708 DOI: 10.3389/fimmu.2019.02582] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 10/17/2019] [Indexed: 01/09/2023] Open
Abstract
Vaccination against Salmonella Typhi using the Vi capsular polysaccharide, a T-cell independent antigen, can protect from the development of typhoid fever. This implies that antibodies to Vi alone can protect in the absence of a T cell-mediated immune response; however, protective Vi antibodies have not been well-characterized. We hypothesized that variability in the biophysical properties of vaccine-elicited antibodies, including subclass distribution and avidity, may impact protective outcomes. To interrogate the relationship between antibody properties and protection against typhoid fever, we analyzed humoral responses from participants in a vaccine efficacy (VE) trial using a controlled human infection model (CHIM) who received either a purified Vi polysaccharide (Vi-PS) or Vi tetanus toxoid conjugate (Vi-TT) vaccine followed by oral challenge with live S. Typhi. We determined the avidity, overall magnitude, and vaccine-induced fold-change in magnitude from before immunization to day of challenge of Vi IgA and IgG subclass antibodies. Amongst those who received the Vi-PS vaccine, Vi IgA magnitude (FDR p = 0.01) and fold-change (FDR p = 0.02) were significantly higher in protected individuals compared with those individuals who developed disease ("diagnosed"). In the Vi-TT vaccine group, the responses of protected individuals had higher fold-change in Vi IgA (FDR p = 0.06) and higher Vi IgG1 avidity (FDR p = 0.058) than the diagnosed Vi-TT vaccinees, though these findings were not significant at p < 0.05. Overall, protective antibody signatures differed between the Vi-PS and Vi-TT vaccines, thus, we conclude that although the Vi-PS and Vi-TT vaccines were observed to have similar efficacies, these vaccines may protect through different mechanisms. These data will inform studies on mechanisms of protection against typhoid fever, including identification of antibody effector functions, as well as informing future vaccination strategies.
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Affiliation(s)
- Lindsay C Dahora
- Duke Human Vaccine Institute, Duke University, Durham, NC, United States.,Department of Immunology, Duke University, Durham, NC, United States
| | - Celina Jin
- Oxford Vaccine Group, Department of Paediatrics, The NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
| | - Rachel L Spreng
- Duke Human Vaccine Institute, Duke University, Durham, NC, United States.,Department of Medicine, Duke University, Durham, NC, United States
| | - Frederick Feely
- Duke Human Vaccine Institute, Duke University, Durham, NC, United States.,Department of Surgery, Duke University, Durham, NC, United States
| | - Ryan Mathura
- Duke Human Vaccine Institute, Duke University, Durham, NC, United States.,Department of Surgery, Duke University, Durham, NC, United States
| | - Kelly E Seaton
- Duke Human Vaccine Institute, Duke University, Durham, NC, United States.,Department of Surgery, Duke University, Durham, NC, United States
| | - Lu Zhang
- Duke Human Vaccine Institute, Duke University, Durham, NC, United States.,Department of Surgery, Duke University, Durham, NC, United States
| | - Jennifer Hill
- Oxford Vaccine Group, Department of Paediatrics, The NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
| | - Elizabeth Jones
- Oxford Vaccine Group, Department of Paediatrics, The NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
| | - S Munir Alam
- Duke Human Vaccine Institute, Duke University, Durham, NC, United States.,Department of Medicine, Duke University, Durham, NC, United States.,Department of Pathology, Duke University, Durham, NC, United States
| | - S Moses Dennison
- Duke Human Vaccine Institute, Duke University, Durham, NC, United States.,Department of Surgery, Duke University, Durham, NC, United States
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, The NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
| | - Georgia D Tomaras
- Duke Human Vaccine Institute, Duke University, Durham, NC, United States.,Department of Immunology, Duke University, Durham, NC, United States.,Department of Surgery, Duke University, Durham, NC, United States.,Molecular Genetics and Microbiology, Duke University, Durham, NC, United States
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161
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Voysey M, Pollard AJ. Seroefficacy of Vi Polysaccharide-Tetanus Toxoid Typhoid Conjugate Vaccine (Typbar TCV). Clin Infect Dis 2019; 67:18-24. [PMID: 29351594 DOI: 10.1093/cid/cix1145] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 01/04/2018] [Indexed: 11/14/2022] Open
Abstract
Background Salmonella Typhi is the major cause of enteric fever in lower-income countries. New conjugate vaccines show promise as public health interventions, but there are no efficacy data available from endemic areas. Methods Data were obtained from a previously published phase 3 randomized controlled trial comparing Vi polysaccharide-tetanus toxoid conjugate vaccine (Vi-TT) with Vi polysaccharide vaccine (Vi-PS) in participants aged 2-45 years. An additional open-label arm administered Vi-TT to children aged 6-23 months. The proportion of participants with presumed clinical or subclinical infection ("seroincidence") was determined using mixture models and compared using relative risks (RRs). Results Of 387 participants, 81 (21%) were classified as having presumed typhoid infection during the 2-year postvaccination period. Seroincidence was lower in participants randomized to Vi-TT rather than Vi-PS among those aged 2-45 years (RR, 0.372; 95% confidence interval [CI], .235-.588; P < .001) and those aged 2-15 years (RR, 0.424; 95% CI, .231-.778; P = .004). There was no difference in seroincidence for Vi-TT between those aged 2-45 years and those aged 6-23 months (RR, 1.073; 95% CI, .563-2.046; P = .83). Vaccine seroefficacy was 85% (95% CI, 80%-88%). Conclusion This is the first field estimate of the seroefficacy of a Vi-TT vaccine and shows that Typbar TCV substantially reduces the number of serologically defined clinical or subclinical infections in infants, children, and adults. These results support the recent World Health Organization recommendations for deployment of typhoid conjugate vaccines in high-burden areas.
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Affiliation(s)
- Merryn Voysey
- Nuffield Department of Primary Care Health Sciences, University of Oxford, United Kingdom.,Oxford Vaccine Group, Department of Paediatrics, University of Oxford, United Kingdom
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, United Kingdom.,NIHR Oxford Biomedical Research Centre, United Kingdom
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162
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Pitzer VE, Meiring J, Martineau FP, Watson CH, Kang G, Basnyat B, Baker S. The Invisible Burden: Diagnosing and Combatting Typhoid Fever in Asia and Africa. Clin Infect Dis 2019; 69:S395-S401. [PMID: 31612938 PMCID: PMC6792124 DOI: 10.1093/cid/ciz611] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Measuring the burden of typhoid fever and developing effective strategies to reduce it require a surveillance infrastructure that is currently lacking in many endemic countries. Recent efforts and partnerships between local and international researchers have helped to provide new data on the incidence and control of typhoid in parts of Asia and Africa. Here, we highlight examples from India, Nepal, Vietnam, Fiji, Sierra Leone, and Malawi that summarize past and present experiences with the diagnosis, treatment, and prevention of typhoid fever in different locations with endemic disease. While there is no validated road map for the elimination of typhoid, the lessons learned in studying the epidemiology and control of typhoid in these settings can provide insights to guide future disease control efforts.
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Affiliation(s)
- Virginia E Pitzer
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, Yale University, New Haven, Connecticut
| | - James Meiring
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, United Kingdom
| | | | - Conall H Watson
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, United Kingdom
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, United Kingdom
| | - Gagandeep Kang
- Translational Health Sciences Technology Institute, Faridabad, Haryana, India
| | - Buddha Basnyat
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, United Kingdom
- Oxford University Clinical Research Unit, Patan Academy of Health Sciences, Kathmandu, Nepal
| | - Stephen Baker
- Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
- Department of Medicine, University of Cambridge, United Kingdom
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163
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Meiring JE, Giubilini A, Savulescu J, Pitzer VE, Pollard AJ. Generating the Evidence for Typhoid Vaccine Introduction: Considerations for Global Disease Burden Estimates and Vaccine Testing Through Human Challenge. Clin Infect Dis 2019; 69:S402-S407. [PMID: 31612941 PMCID: PMC6792111 DOI: 10.1093/cid/ciz630] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Typhoid fever has had a major impact on human populations, with the causative pathogen Salmonella enterica serovar Typhi implicated in many outbreaks through history. The current burden of disease is estimated at 11-18 million infections annually, with the majority of infections located in Africa and South Asia. Data that have been used to estimate burden are limited to a small number of blood-culture surveillance studies, largely from densely populated urban centers. Extrapolating these data to estimate disease burden within and across countries highlights the lack of precision in global figures. A number of approaches have been developed, characterizing different geographical areas by water-based risk factors for typhoid infection or broader measures of health and development to more accurately extrapolate incidence. Recognition of the substantial disease burden is essential for policy-makers considering vaccine introduction. Typhoid vaccines have been in development for >100 years. The Vi polysaccharide (ViPS) and Ty21a vaccines have had a World Health Organization (WHO) recommendation for programmatic use in countries with high burden for 10 years, with 1 ViPS vaccine also having WHO prequalification. Despite this, uptake and introduction of these vaccines has been minimal. The development of a controlled human infection model (CHIM) enabled the accelerated testing of the newly WHO-prequalified ViPS-tetanus toxoid protein conjugate vaccine, providing efficacy estimates for the vaccine, prior to larger field trials. There is an urgency to the global control of enteric fever due to the escalating problem of antimicrobial resistance. With more accurate burden of disease estimates and a vaccine showing efficacy in CHIM, that control is now a possibility.
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Affiliation(s)
- James E Meiring
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, United Kingdom
- National Institute for Health Research Oxford Biomedical Research Centre, University of Oxford, United Kingdom
| | - Alberto Giubilini
- Oxford Uehiro Centre for Practical Ethics, University of Oxford, United Kingdom
| | - Julian Savulescu
- Oxford Uehiro Centre for Practical Ethics, University of Oxford, United Kingdom
| | - Virginia E Pitzer
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, Yale University, New Haven, Connecticut
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, United Kingdom
- National Institute for Health Research Oxford Biomedical Research Centre, University of Oxford, United Kingdom
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164
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Oguti B, Gibani M, Darlow C, Waddington CS, Jin C, Plested E, Campbell D, Jones C, Darton TC, Pollard AJ. Factors influencing participation in controlled human infection models: a pooled analysis from six enteric fever studies. Wellcome Open Res 2019. [DOI: 10.12688/wellcomeopenres.15469.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Background: Enteric fever is an acute febrile-illness caused by infection with the human-restricted Salmonella serovars Typhi and Paratyphi. Controlled human infection models (CHIM) of S. Typhi and Paratyphi infection are used to accelerate vaccine development and to better understand host-pathogen interactions. The primary motivations for participants to take part in these studies are unknown. We studied participant motivations, attitudes and the factors influencing CHIM study participation. Methods: Participant surveys were nested in six enteric fever CHIM studies conducted at a single centre in Oxford, UK, between 2011 and 2017. All eligible participants received one invitation to complete an anonymous, self-administered paper or online survey on either day 28 or 60 after challenge. A descriptive analysis was performed on these pooled data. All studies were included, to minimize selection bias. Results: Survey response rates varied from 33.0%-86.1%, yielding 201 participants. In the cohort, 113/198(57.0%) were educated to bachelor’s level, 61.6% were employed, 30.3% were students and 4.6% were unemployed. The most commonly cited motivations for CHIM study participation were a desire to contribute to the progression of medicine (170/201; 84.6%); the prospect of financial reimbursement (166/201; 82.6%) and curiosity about clinical trials (117/201; 57.2%). The majority of respondents (139/197; 70.6%) reported that most people advised them against participation. Conclusion: Motivation to participate in a CHIM study was multi-factorial and heavily influenced by internal drivers beyond monetary reimbursement alone. High educational attainment and employment may be protective factors against financial inducement; however, further research is needed, particularly with CHIM studies expanding to low-income and middle-income countries.
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165
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Blohmke CJ, Muller J, Gibani MM, Dobinson H, Shrestha S, Perinparajah S, Jin C, Hughes H, Blackwell L, Dongol S, Karkey A, Schreiber F, Pickard D, Basnyat B, Dougan G, Baker S, Pollard AJ, Darton TC. Diagnostic host gene signature for distinguishing enteric fever from other febrile diseases. EMBO Mol Med 2019; 11:e10431. [PMID: 31468702 PMCID: PMC6783646 DOI: 10.15252/emmm.201910431] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 07/30/2019] [Accepted: 08/09/2019] [Indexed: 12/19/2022] Open
Abstract
Misdiagnosis of enteric fever is a major global health problem, resulting in patient mismanagement, antimicrobial misuse and inaccurate disease burden estimates. Applying a machine learning algorithm to host gene expression profiles, we identified a diagnostic signature, which could distinguish culture-confirmed enteric fever cases from other febrile illnesses (area under receiver operating characteristic curve > 95%). Applying this signature to a culture-negative suspected enteric fever cohort in Nepal identified a further 12.6% as likely true cases. Our analysis highlights the power of data-driven approaches to identify host response patterns for the diagnosis of febrile illnesses. Expression signatures were validated using qPCR, highlighting their utility as PCR-based diagnostics for use in endemic settings.
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Affiliation(s)
- Christoph J Blohmke
- Department of PaediatricsCentre for Clinical Vaccinology and Tropical MedicineOxford Vaccine GroupOxfordUK
- Oxford National Institute of Health Research Biomedical CentreUniversity of OxfordOxfordUK
| | | | - Malick M Gibani
- Department of PaediatricsCentre for Clinical Vaccinology and Tropical MedicineOxford Vaccine GroupOxfordUK
- Oxford National Institute of Health Research Biomedical CentreUniversity of OxfordOxfordUK
| | - Hazel Dobinson
- Department of PaediatricsCentre for Clinical Vaccinology and Tropical MedicineOxford Vaccine GroupOxfordUK
- Oxford National Institute of Health Research Biomedical CentreUniversity of OxfordOxfordUK
| | - Sonu Shrestha
- Department of PaediatricsCentre for Clinical Vaccinology and Tropical MedicineOxford Vaccine GroupOxfordUK
- Oxford National Institute of Health Research Biomedical CentreUniversity of OxfordOxfordUK
| | - Soumya Perinparajah
- Department of PaediatricsCentre for Clinical Vaccinology and Tropical MedicineOxford Vaccine GroupOxfordUK
- Oxford National Institute of Health Research Biomedical CentreUniversity of OxfordOxfordUK
| | - Celina Jin
- Department of PaediatricsCentre for Clinical Vaccinology and Tropical MedicineOxford Vaccine GroupOxfordUK
- Oxford National Institute of Health Research Biomedical CentreUniversity of OxfordOxfordUK
| | - Harri Hughes
- Department of PaediatricsCentre for Clinical Vaccinology and Tropical MedicineOxford Vaccine GroupOxfordUK
- Oxford National Institute of Health Research Biomedical CentreUniversity of OxfordOxfordUK
| | - Luke Blackwell
- Department of PaediatricsCentre for Clinical Vaccinology and Tropical MedicineOxford Vaccine GroupOxfordUK
- Oxford National Institute of Health Research Biomedical CentreUniversity of OxfordOxfordUK
| | - Sabina Dongol
- Patan Academy of Healthy SciencesOxford University Clinical Research UnitKathmanduNepal
| | - Abhilasha Karkey
- Patan Academy of Healthy SciencesOxford University Clinical Research UnitKathmanduNepal
| | | | - Derek Pickard
- Infection Genomics ProgramThe Wellcome Trust Sanger InstituteHinxtonUK
| | - Buddha Basnyat
- Patan Academy of Healthy SciencesOxford University Clinical Research UnitKathmanduNepal
| | - Gordon Dougan
- Infection Genomics ProgramThe Wellcome Trust Sanger InstituteHinxtonUK
| | - Stephen Baker
- The Hospital for Tropical DiseasesWellcome Trust Major Overseas ProgrammeOxford University Clinical Research UnitHo Chi Minh CityVietnam
| | - Andrew J Pollard
- Department of PaediatricsCentre for Clinical Vaccinology and Tropical MedicineOxford Vaccine GroupOxfordUK
- Oxford National Institute of Health Research Biomedical CentreUniversity of OxfordOxfordUK
| | - Thomas C Darton
- Department of PaediatricsCentre for Clinical Vaccinology and Tropical MedicineOxford Vaccine GroupOxfordUK
- Oxford National Institute of Health Research Biomedical CentreUniversity of OxfordOxfordUK
- The Hospital for Tropical DiseasesWellcome Trust Major Overseas ProgrammeOxford University Clinical Research UnitHo Chi Minh CityVietnam
- Department of Infection, Immunity and Cardiovascular DiseaseUniversity of SheffieldSheffieldUK
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166
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Basnyat B, Karkey A. Tackling typhoid fever in South Asia: lessons from Vietnam. LANCET GLOBAL HEALTH 2019; 7:e1317-e1318. [PMID: 31537355 DOI: 10.1016/s2214-109x(19)30320-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 07/07/2019] [Indexed: 11/19/2022]
Affiliation(s)
- Buddha Basnyat
- Oxford University Clinical Research Unit-Nepal, Patan Academy of Health Science, Kathmandu, PO Box 3596, Nepal.
| | - Abhilasha Karkey
- Oxford University Clinical Research Unit-Nepal, Patan Academy of Health Science, Kathmandu, PO Box 3596, Nepal
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167
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Barkume C, Date K, Saha SK, Qamar FN, Sur D, Andrews JR, Luby SP, Khan MI, Freeman A, Yousafzai MT, Garrett D. Phase I of the Surveillance for Enteric Fever in Asia Project (SEAP): An Overview and Lessons Learned. J Infect Dis 2019; 218:S188-S194. [PMID: 30304505 PMCID: PMC6226726 DOI: 10.1093/infdis/jiy522] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 09/05/2018] [Indexed: 11/14/2022] Open
Abstract
Objective The objective of Phase I of the Surveillance for Enteric Fever in Asia Project (SEAP), a multiphase surveillance study characterizing the burden of disease in South Asia, was to inform data collection for prospective surveillance and to capture clinical aspects of disease. Methods Through a retrospective record review conducted at hospitals in Bangladesh, India, Nepal, and Pakistan, we examined laboratory and clinical records to assess the culture positivity rate for Salmonella Typhi and Salmonella Paratyphi, age and sex distribution, and antimicrobial susceptability in each country. Results Of all blood cultures performed in Bangladesh, India, Nepal, and Pakistan, 1.5%, 0.43%, 2%, and 1.49%, respectively, were positive for S. Typhi and 0.24%, 0.1%, 0.5%, and 0.67%, respectively, were positive for S. Paratyphi. A higher proportion of laboratory-confirmed infections in Bangladesh and Pakistan were aged ≤5 years, while India and Nepal had a higher proportion of participants aged 15–25 years. In all countries, the sex of the majority of participants was male. The majority of isolates in all countries were resistant to fluoroquinolones, with a high proportion also resistant to ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole. Discussion Enteric fever remains endemic in South Asia. Data generated by this study can help inform strategies for implementation and evaluation of prevention and control measures.
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Affiliation(s)
| | - Kashmira Date
- Global Immunization Division, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Samir K Saha
- Child Health Research Foundation, Department of Microbiology, Dhaka Shishu (Children) Hospital, Bangladesh
| | - Farah Naz Qamar
- Department of Pediatrics and Child Health, Aga Khan University, Karachi, Pakistan
| | - Dipika Sur
- Translational Health Science and Technology Institute, Faridabad, India
| | - Jason R Andrews
- Infectious Diseases and Geographic Medicine, Stanford University, California
| | - Stephen P Luby
- Infectious Diseases and Geographic Medicine, Stanford University, California
| | - M Imran Khan
- Typhoid Programs, Sabin Vaccine Institute, Washington, D. C
| | - Alex Freeman
- Typhoid Programs, Sabin Vaccine Institute, Washington, D. C
| | | | - Denise Garrett
- Typhoid Programs, Sabin Vaccine Institute, Washington, D. C
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168
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Bentsi-Enchill AD, Pollard AJ. A Turning Point in Typhoid Control. J Infect Dis 2019; 218:S185-S187. [PMID: 30189009 PMCID: PMC6226784 DOI: 10.1093/infdis/jiy417] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 08/29/2018] [Indexed: 12/03/2022] Open
Affiliation(s)
- Adwoa D Bentsi-Enchill
- Department of Immunization, Vaccines and Biologicals, World Health Organization, Geneva, Switzerland
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, United Kingdom.,National Institute for Health Research Oxford Biomedical Research Centre, United Kingdom
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169
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Sur D, Barkume C, Mukhopadhyay B, Date K, Ganguly NK, Garrett D. A Retrospective Review of Hospital-Based Data on Enteric Fever in India, 2014-2015. J Infect Dis 2019; 218:S206-S213. [PMID: 30307566 PMCID: PMC6226629 DOI: 10.1093/infdis/jiy502] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 08/21/2018] [Indexed: 01/17/2023] Open
Abstract
Background Enteric fever remains a threat to many countries with minimal access to clean water and poor sanitation infrastructure. As part of a multisite surveillance study, we conducted a retrospective review of records in 5 hospitals across India to gather evidence on the burden of enteric fever. Methods We examined hospital records (laboratory and surgical registers) from 5 hospitals across India for laboratory-confirmed Salmonella Typhi or Salmonella Paratyphi cases and intestinal perforations from 2014–2015. Clinical data were obtained where available. For laboratory-confirmed infections, we compared differences in disease burden, age, sex, clinical presentation, and antimicrobial resistance. Results Of 267536 blood cultures, 1418 (0.53%) were positive for S. Typhi or S. Paratyphi. Clinical data were available for 429 cases (72%); a higher proportion of participants with S. Typhi infection were hospitalized, compared with those with S. Paratyphi infection (44% vs 35%). We observed resistance to quinolones among 82% of isolates, with cases of cephalosporin resistance (1%) and macrolide resistance (9%) detected. Of 94 participants with intestinal perforations, 16 (17%) had a provisional, final, or laboratory-confirmed diagnosis of enteric fever. Discussion Data show a moderate burden of enteric fever in India. Enteric fever data should be systematically collected to facilitate evidence-based decision-making by countries for typhoid conjugate vaccines.
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Affiliation(s)
- Dipika Sur
- Translational Health Science and Technology Institute, Faridabad, India
| | | | | | - Kashmira Date
- Global Immunization Division, Centers for Disease Control and Prevention, Atlanta, Georgia
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170
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Awofisayo-Okuyelu A, Pratt A, McCarthy N, Hall I. Within-host mathematical modelling of the incubation period of Salmonella Typhi. ROYAL SOCIETY OPEN SCIENCE 2019; 6:182143. [PMID: 31598273 PMCID: PMC6774937 DOI: 10.1098/rsos.182143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Accepted: 08/06/2019] [Indexed: 06/10/2023]
Abstract
Mechanistic mathematical models are often employed to understand the dynamics of infectious diseases within a population or within a host. They provide estimates that may not be otherwise available. We have developed a within-host mathematical model in order to understand how the pathophysiology of Salmonella Typhi contributes to its incubation period. The model describes the process of infection from ingestion to the onset of clinical illness using a set of ordinary differential equations. The model was parametrized using estimated values from human and mouse experimental studies and the incubation period was estimated as 9.6 days. A sensitivity analysis was also conducted to identify the parameters that most affect the derived incubation period. The migration of bacteria to the caecal lymph node was observed as a major bottle neck for infection. The sensitivity analysis indicated the growth rate of bacteria in late phase systemic infection and the net population of bacteria in the colon as parameters that most influence the incubation period. We have shown in this study how mathematical models aid in the understanding of biological processes and can be used in estimating parameters of infectious diseases.
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Affiliation(s)
- Adedoyin Awofisayo-Okuyelu
- National Institute of Health Research Health Protection Research Unit in Gastrointestinal Infections, University of Oxford, Oxford, UK
- Department of Zoology, University of Oxford, Oxford, UK
| | - Adrian Pratt
- Emergency Response Department Science and Technology (ERD S&T), Health Protection Directorate, Public Health England, Porton Down, UK
| | - Noel McCarthy
- National Institute of Health Research Health Protection Research Unit in Gastrointestinal Infections, University of Oxford, Oxford, UK
- Department of Zoology, University of Oxford, Oxford, UK
- Warwick Medical School, University of Warwick, Coventry, UK
| | - Ian Hall
- School of Mathematics, University of Manchester, Manchester, UK
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171
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Arnold BF, Martin DL, Juma J, Mkocha H, Ochieng JB, Cooley GM, Omore R, Goodhew EB, Morris JF, Costantini V, Vinjé J, Lammie PJ, Priest JW. Enteropathogen antibody dynamics and force of infection among children in low-resource settings. eLife 2019; 8:45594. [PMID: 31424386 PMCID: PMC6746552 DOI: 10.7554/elife.45594] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 08/15/2019] [Indexed: 01/22/2023] Open
Abstract
Little is known about enteropathogen seroepidemiology among children in low-resource settings. We measured serological IgG responses to eight enteropathogens (Giardia intestinalis, Cryptosporidium parvum, Entamoeba histolytica, Salmonella enterica, enterotoxigenic Escherichia coli, Vibrio cholerae, Campylobacter jejuni, norovirus) in cohorts from Haiti, Kenya, and Tanzania. We studied antibody dynamics and force of infection across pathogens and cohorts. Enteropathogens shared common seroepidemiologic features that enabled between-pathogen comparisons of transmission. Overall, exposure was intense: for most pathogens the window of primary infection was <3 years old; for highest transmission pathogens primary infection occurred within the first year. Longitudinal profiles demonstrated significant IgG boosting and waning above seropositivity cutoffs, underscoring the value of longitudinal designs to estimate force of infection. Seroprevalence and force of infection were rank-preserving across pathogens, illustrating the measures provide similar information about transmission heterogeneity. Our findings suggest antibody response can be used to measure population-level transmission of diverse enteropathogens in serologic surveillance. Diarrhea, which is caused by bacteria such as Salmonella or by viruses like norovirus, is the fourth leading cause of death among children worldwide, with children in low-resource settings being at highest risk. The pathogens that cause diarrhea spread when stool from infected people comes into contact with new hosts, for example, through inadequate sanitation or by drinking contaminated water. Currently, the best way to track these infections is to collect stool samples from people and test them for the presence of the pathogens. Unfortunately, this is costly and difficult to do on a large scale outside of clinical settings, making it hard to track the spread of diarrhea-causing pathogens. The body produces antibodies – small proteins that can detect specific pathogens – in response to an infection. These antibodies help ward off future infections by the same pathogen, so if they are present in the blood, this indicates a current or previous infection. Scientists already collect blood samples to track malaria, HIV and vaccine-preventable diseases in low-resource settings. These samples could be tested more broadly to measure the levels of antibodies against diarrhea-causing pathogens. Now, Arnold et al. have used blood samples collected from children in Haiti, Kenya, and Tanzania to measure antibody responses to 8 diarrhea-causing pathogens. The results showed that many children in these settings had been infected with all 8 pathogens before age three, and that all of the pathogens shared similar age-dependent patterns of antibody response. This finding enabled Arnold et al. to combine antibody measurements with statistical models to estimate each pathogen’s force of infection, that is, the rate at which susceptible individuals in the population become infected. This is a key step for epidemiologists to understand which pathogens cause the most infections in a population. The experiments show that testing blood samples for antibodies could provide scientists with a new tool to track the transmission of diarrhea-causing pathogens in low-resource settings. This information could help public health officials design and test efforts to prevent diarrhea, for example, by improving water treatment or developing vaccines.
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Affiliation(s)
- Benjamin F Arnold
- Division of Epidemiology and Biostatistics, University of California, Berkeley, Berkeley, United States.,Francis I. Proctor Foundation, University of California, San Francisco, San Francisco, United States.,Department of Ophthalmology, University of California, San Francisco, San Francisco, United States
| | - Diana L Martin
- Division of Parasitic Diseases and Malaria, United States Centers for Disease Control and Prevention, Atlanta, United States
| | - Jane Juma
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - Harran Mkocha
- Kongwa Trachoma Project, Kongwa, United Republic of Tanzania
| | - John B Ochieng
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - Gretchen M Cooley
- Division of Parasitic Diseases and Malaria, United States Centers for Disease Control and Prevention, Atlanta, United States
| | - Richard Omore
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - E Brook Goodhew
- Division of Parasitic Diseases and Malaria, United States Centers for Disease Control and Prevention, Atlanta, United States
| | - Jamae F Morris
- Department of African-American Studies, Georgia State University, Atlanta, United States
| | - Veronica Costantini
- Division of Viral Diseases, United States Centers for Disease Control and Prevention, Atlanta, United States
| | - Jan Vinjé
- Division of Viral Diseases, United States Centers for Disease Control and Prevention, Atlanta, United States
| | - Patrick J Lammie
- Division of Parasitic Diseases and Malaria, United States Centers for Disease Control and Prevention, Atlanta, United States.,Neglected Tropical Diseases Support Center, Task Force for Global Health, Decatur, United States
| | - Jeffrey W Priest
- Division of Foodborne, Waterborne, and Environmental Diseases, United States Centers for Disease Control and Prevention, Atlanta, United States
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173
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Abstract
Purpose of review Enteric fever remains a major global-health concern, estimated to be responsible for between 11.9 and 26.9 million cases annually. Long-term prevention of enteric fever will require improved access to safe drinking water combined with investment in sanitation and hygiene interventions. In the short-to-medium term, new control strategies for typhoid fever have arrived in the form of typhoid Vi-conjugate vaccines (TCVs), offering hope that disease control can be achieved in the near future. Recent findings The diagnosis of enteric fever is complicated by its nonspecific clinical presentation, coupled with the low sensitivity of commonly used diagnostics. Investment in diagnostics has the potential to improve management, to refine estimates of disease burden and to facilitate vaccine impact studies. A new generation of reliable, diagnostic tests is needed that are simultaneously accessible, cost-effective, sensitive, and specific. The emergence and global dissemination of multidrug-resistant, fluoroquinolone-resistant, and extensively drug-resistant (XDR) strains of Salmonella Typhi emphasizes the importance of continued surveillance and appropriate antibiotic stewardship, integrated into a global strategy to address antimicrobial resistance (AMR). Current empirical treatment guidelines are out of date and should be updated to respond to local trends in AMR, so as to guide treatment choices in the absence of robust diagnostics and laboratory facilities. In September 2017, the WHO Strategic Advisory Group of Experts (SAGE) immunization recommended the programmatic use of TCVs in high burden countries. Ongoing and future studies should aim to study the impact of these vaccines in a diverse range of setting and to support the deployment of TCVs in high-burden countries. Summary The advent of new generation TCVs offers us a practical and affordable public-health tool that – for the first time – can be integrated into routine childhood immunization programmes. In this review, we advocate for the deployment of TCVs in line with WHO recommendations, to improve child health and limit the spread of antibiotic-resistant S. Typhi.
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Gibani MM, Jones E, Barton A, Jin C, Meek J, Camara S, Galal U, Heinz E, Rosenberg-Hasson Y, Obermoser G, Jones C, Campbell D, Black C, Thomaides-Brears H, Darlow C, Dold C, Silva-Reyes L, Blackwell L, Lara-Tejero M, Jiao X, Stack G, Blohmke CJ, Hill J, Angus B, Dougan G, Galán J, Pollard AJ. Investigation of the role of typhoid toxin in acute typhoid fever in a human challenge model. Nat Med 2019; 25:1082-1088. [PMID: 31270506 PMCID: PMC6892374 DOI: 10.1038/s41591-019-0505-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Accepted: 05/30/2019] [Indexed: 11/09/2022]
Abstract
Salmonella Typhi is a human host-restricted pathogen that is responsible for typhoid fever in approximately 10.9 million people annually1. The typhoid toxin is postulated to have a central role in disease pathogenesis, the establishment of chronic infection and human host restriction2–6. However, its precise role in typhoid disease in humans is not fully defined. We studied the role of typhoid toxin in acute infection using a randomized, double-blind S. Typhi human challenge model7. Forty healthy volunteers were randomized (1:1) to oral challenge with 104 colony-forming units of wild-type or an isogenic typhoid toxin deletion mutant (TN) of S. Typhi. We observed no significant difference in the rate of typhoid infection (fever ≥38 °C for ≥12 h and/or S. Typhi bacteremia) between participants challenged with wild-type or TN S. Typhi (15 out of 21 (71%) versus 15 out of 19 (79%); P = 0.58). The duration of bacteremia was significantly longer in participants challenged with the TN strain compared with wild-type (47.6 hours (28.9–97.0) versus 30.3(3.6–49.4); P ≤ 0.001). The clinical syndrome was otherwise indistinguishable between wild-type and TN groups. These data suggest that the typhoid toxin is not required for infection and the development of early typhoid fever symptoms within the context of a human challenge model. Further clinical data are required to assess the role of typhoid toxin in severe disease or the establishment of bacterial carriage. Typhoid toxin is not essential for the pathogenesis of typhoid fever in healthy humans challenged with Salmonella Typhi.
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Affiliation(s)
- Malick M Gibani
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK. .,Department of Medicine, Imperial College London, London, UK.
| | - Elizabeth Jones
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Amber Barton
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Celina Jin
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Juliette Meek
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Susana Camara
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Ushma Galal
- Nuffield Department of Primary Care Health Sciences, Clinical Trials Unit, University of Oxford, Oxford, UK
| | - Eva Heinz
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, UK.,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Yael Rosenberg-Hasson
- Human Immune Monitoring Center, Institute for Immunity, Transplantation and Infection, Stanford University, Stanford, CA, USA
| | - Gerlinde Obermoser
- Human Immune Monitoring Center, Institute for Immunity, Transplantation and Infection, Stanford University, Stanford, CA, USA
| | - Claire Jones
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Danielle Campbell
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Charlotte Black
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Helena Thomaides-Brears
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Christopher Darlow
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Christina Dold
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Laura Silva-Reyes
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Luke Blackwell
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Maria Lara-Tejero
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Xuyao Jiao
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Gabrielle Stack
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Christoph J Blohmke
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Jennifer Hill
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Brian Angus
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Gordon Dougan
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, UK.,Department of Medicine, University of Cambridge, Hinxton, UK
| | - Jorge Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, UK
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Bilcke J, Antillón M, Pieters Z, Kuylen E, Abboud L, Neuzil KM, Pollard AJ, Paltiel AD, Pitzer VE. Cost-effectiveness of routine and campaign use of typhoid Vi-conjugate vaccine in Gavi-eligible countries: a modelling study. THE LANCET. INFECTIOUS DISEASES 2019; 19:728-739. [PMID: 31130329 PMCID: PMC6595249 DOI: 10.1016/s1473-3099(18)30804-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 12/10/2018] [Accepted: 12/14/2018] [Indexed: 12/14/2022]
Abstract
BACKGROUND Typhoid fever is a major cause of morbidity and mortality in low-income and middle-income countries. In 2017, WHO recommended the programmatic use of typhoid Vi-conjugate vaccine (TCV) in endemic settings, and Gavi, The Vaccine Alliance, has pledged support for vaccine introduction in these countries. Country-level health economic evaluations are now needed to inform decision-making. METHODS In this modelling study, we compared four strategies: no vaccination, routine immunisation at 9 months, and routine immunisation at 9 months with catch-up campaigns to either age 5 years or 15 years. For each of the 54 countries eligible for Gavi support, output from an age-structured transmission-dynamic model was combined with country-specific treatment and vaccine-related costs, treatment outcomes, and disability weights to estimate the reduction in typhoid burden, identify the strategy that maximised average net benefit (ie, the optimal strategy) across a range of country-specific willingness-to-pay (WTP) values, estimate and investigate the uncertainties surrounding our findings, and identify the epidemiological conditions under which vaccination is optimal. FINDINGS The optimal strategy was either no vaccination or TCV immunisation including a catch-up campaign. Routine vaccination with a catch-up campaign to 15 years of age was optimal in 38 countries, assuming a WTP value of at least US$200 per disability-adjusted life-year (DALY) averted, or assuming a WTP value of at least 25% of each country's gross domestic product (GDP) per capita per DALY averted, at a vaccine price of $1·50 per dose (but excluding Gavi's contribution according to each country's transition phase). This vaccination strategy was also optimal in 48 countries assuming a WTP of at least $500 per DALY averted, in 51 with assumed WTP values of at least $1000, in 47 countries assuming a WTP value of at least 50% of GDP per capita per DALY averted, and in 49 assuming a minimum of 100%. Vaccination was likely to be cost-effective in countries with 300 or more typhoid cases per 100 000 person-years. Uncertainty about the probability of hospital admission (and typhoid incidence and mortality) had the greatest influence on the optimal strategy. INTERPRETATION Countries should establish their own WTP threshold and consider routine TCV introduction, including a catch-up campaign when vaccination is optimal on the basis of this threshold. Obtaining improved estimates of the probability of hospital admission would be valuable whenever the optimal strategy is uncertain. FUNDING Bill & Melinda Gates Foundation, Research Foundation-Flanders, and the Belgian-American Education Foundation.
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Affiliation(s)
- Joke Bilcke
- Centre for Health Economics Research and Modeling Infectious Diseases, Vaccine and Infectious Disease Institute, University of Antwerp, Antwerp, Belgium.
| | - Marina Antillón
- Centre for Health Economics Research and Modeling Infectious Diseases, Vaccine and Infectious Disease Institute, University of Antwerp, Antwerp, Belgium; Department of Epidemiology of Microbial Diseases, Yale School of Public Health, Yale University, New Haven, CT, USA
| | - Zoë Pieters
- Centre for Health Economics Research and Modeling Infectious Diseases, Vaccine and Infectious Disease Institute, University of Antwerp, Antwerp, Belgium; Center for Statistics, I-Biostat, Hasselt University, Diepenbeek, Belgium
| | - Elise Kuylen
- Centre for Health Economics Research and Modeling Infectious Diseases, Vaccine and Infectious Disease Institute, University of Antwerp, Antwerp, Belgium
| | - Linda Abboud
- Centre for Health Economics Research and Modeling Infectious Diseases, Vaccine and Infectious Disease Institute, University of Antwerp, Antwerp, Belgium
| | - Kathleen M Neuzil
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the National Institute for Health Research Oxford Biomedical Research Centre, Oxford, UK
| | - A David Paltiel
- Department of Health Policy and Management, Yale School of Public Health, Yale University, New Haven, CT, USA
| | - Virginia E Pitzer
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, Yale University, New Haven, CT, USA.
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Tang F, Chen Z, Wang F, Hou H, Liu W, Xiao H, Hu J, Xiong Y, Zhang H, Chen Z, Peng H, Lu J, Luo W, Zhao Y, Lin M. Optimization of an efficient solid-phase enrichment medium for Salmonella detection using response surface methodology. AMB Express 2019; 9:97. [PMID: 31254206 PMCID: PMC6598893 DOI: 10.1186/s13568-019-0819-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 06/18/2019] [Indexed: 11/10/2022] Open
Abstract
Salmonella is a pathogenic bacterium contributing to food poisoning and acute infectious intestinal disease. The traditional standard detection method is based on the principle of liquid phase enrichment and has a low sensitivity on targeted bacteria. We previously developed a visual immunosensor technique for efficient detection and isolation of Salmonella by applying fluorescent nanobioprobes on a specially-designed cellulose-based swab. In this study, a whole-sample solid-phase enrichment assay (WSEA) was established by optimization of the enrichment medium using response surface methodology (RSM), a powerful statistical tool for regression analysis. The optimal formula was determined as: 0.60% polyvalent poly peptone, 0.40% buffered peptone water, 0.09% ferric citrate amine, 0.24% sodium hyposulfite, 0.035% cystine, 0.01 µg mL−1 super absorbing polymer, 0.011% sodium deoxycholate, 15.00 µg mL−1 ethyl green and 30.00 µg mL−1 sodium selenite. Using this formula, Salmonella was visualized with naked eyes by relying on the indication of black spots formed on the swab. The analytic sensitivity of the assay was determined as 101 cells mL−1 with a concentration of interfering bacteria (Escherichia coli) at 105 cells mL−1. This optimized formula was confirmed with 4006 patients’ fecal samples, in which the positive rate was 0.42% by the conventional culture-based method and 2.12% by WSEA. The optimized formulation on solid phase enrichment by RSM allows relatively quick, low-cost, and large-scale detection of Salmonella, and could be used in grassroots medical institutions.
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177
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O-acetylation of typhoid capsular polysaccharide confers polysaccharide rigidity and immunodominance by masking additional epitopes. Vaccine 2019; 37:3866-3875. [PMID: 31160100 PMCID: PMC6997886 DOI: 10.1016/j.vaccine.2019.05.050] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 05/13/2019] [Accepted: 05/14/2019] [Indexed: 01/22/2023]
Abstract
The binding of anti-Vi mAb and polyclonal immune sera correlated with the level of O-acetylation. C. freundii Vi resists de-O-acetylation and is more viscous than S. Typhi Vi. Sera from human vaccine recipients contains IgG that recognizes the backbone of Vi. Simulations show O-acetyls are exposed on the surface of Vi and confer rigidity. MD gives conformational rationale for effect of O-acetylation on Vi antigenicity and viscosity.
In this work, we explore the effects of O-acetylation on the physical and immunological characteristics of the WHO International Standards of Vi polysaccharide (Vi) from both Citrobacter freundii and Salmonella enterica serovar Typhi. We find that, although structurally identical according to NMR, the two Vi standards have differences with respect to susceptibility to de-O-acetylation and viscosity in water. Vi standards from both species have equivalent mass and O-acetylation-dependent binding to a mouse monoclonal antibody and to anti-Vi polyclonal antisera, including the WHO International Standard for human anti-typhoid capsular Vi PS IgG. This study also confirms that human anti-Vi sera binds to completely de-O-acetylated Vi. Molecular dynamics simulations provide conformational rationales for the known effect of de-O-acetylation both on the viscosity and antigenicity of the Vi, demonstrating that de-O-acetylation has a very marked effect on the conformation and dynamic behavior of the Vi, changing the capsular polysaccharide from a rigid helix into a more flexible coil, as well as enhancing the strong interaction of the polysaccharide with sodium ions. Partial de-O-acetylation of Vi revealed hidden epitopes that were recognized by human and sheep anti-Vi PS immune sera. These findings have significance for the manufacture and evaluation of Vi vaccines.
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178
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Osowicki J, Azzopardi KI, Baker C, Waddington CS, Pandey M, Schuster T, Grobler A, Cheng AC, Pollard AJ, McCarthy JS, Good MF, Walker MJ, Dale JB, Batzloff MR, Carapetis JR, Smeesters PR, Steer AC. Controlled human infection for vaccination against Streptococcus pyogenes (CHIVAS): Establishing a group A Streptococcus pharyngitis human infection study. Vaccine 2019; 37:3485-3494. [PMID: 31101422 DOI: 10.1016/j.vaccine.2019.03.059] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 03/14/2019] [Accepted: 03/26/2019] [Indexed: 12/17/2022]
Abstract
Group A Streptococcus (GAS) is a highly-adapted and human-restricted pathogen responsible for a high global burden of disease across a diverse clinical spectrum. Vaccine development has been impeded by scientific, regulatory, and commercial obstacles. Human infection studies (HIS) are increasingly contributing to drug, diagnostics, and vaccine development, reducing uncertainty at early stages, especially for pathogens with animal models that incompletely reproduce key elements of human disease. We review the small number of historical GAS HIS and present the study protocol for a dose-ranging inpatient study in healthy adults. The primary objective of the study is to establish a new GAS pharyngitis HIS with an attack rate of at least 60% as a safe and reliable platform for vaccine evaluation and pathogenesis research. According to an adaptive dose-ranging study design, emm75 GAS doses manufactured in keeping with principles of Good Manufacturing Practice will be directly applied by swab to the pharynx of carefully screened healthy adult volunteers at low risk of severe complicated GAS disease. Participants will remain as closely monitored inpatients for up to six days, observed for development of the primary outcome of acute symptomatic pharyngitis, as defined by clinical and microbiological criteria. All participants will be treated with antibiotics and followed as outpatients for six months. An intensive sampling schedule will facilitate extensive studies of host and organism dynamics during experimental pharyngitis. Ethics approval has been obtained and the study has been registered at ClinicalTrials.gov (NCT03361163).
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Affiliation(s)
- Joshua Osowicki
- Tropical Diseases, Murdoch Children's Research Institute, Melbourne, Victoria, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia; Infectious Diseases Unit, Department of General Medicine, The Royal Children's Hospital Melbourne, Victoria, Australia.
| | - Kristy I Azzopardi
- Tropical Diseases, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Ciara Baker
- Tropical Diseases, Murdoch Children's Research Institute, Melbourne, Victoria, Australia
| | - Claire S Waddington
- Telethon Kids Institute, University of Western Australia and Perth Children's Hospital, Perth, Australia; Department of Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Manisha Pandey
- The Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
| | - Tibor Schuster
- Clinical Epidemiology and Biostatistics Unit, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia; Department of Family Medicine, McGill University, Montreal, Quebec, Canada
| | - Anneke Grobler
- Department of Paediatrics, University of Melbourne, Victoria, Australia; Clinical Epidemiology and Biostatistics Unit, Murdoch Childrens Research Institute, Melbourne, Victoria, Australia
| | - Allen C Cheng
- Infection Prevention and Healthcare Epidemiology Unit, The Alfred Hospital, Melbourne, Victoria, Australia; School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria, Australia
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom; National Institute for Health Research, Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - James S McCarthy
- QIMR Berghofer Medical Research Institute, Brisbane, Australia; School of Medicine, University of Queensland, Brisbane, Australia
| | - Michael F Good
- The Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
| | - Mark J Walker
- School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, The University of Queensland, St Lucia, Queensland, Australia
| | - James B Dale
- University of Tennessee Health Science Center, Department of Medicine, Memphis, TN, USA
| | - Michael R Batzloff
- The Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
| | - Jonathan R Carapetis
- Telethon Kids Institute, University of Western Australia and Perth Children's Hospital, Perth, Australia
| | - Pierre R Smeesters
- Tropical Diseases, Murdoch Children's Research Institute, Melbourne, Victoria, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia; Paediatric Department, Academic Children Hospital Queen Fabiola, Université Libre de Bruxelles, Brussels, Belgium; Molecular Bacteriology Laboratory, Université Libre de Bruxelles, Brussels, Belgium
| | - Andrew C Steer
- Tropical Diseases, Murdoch Children's Research Institute, Melbourne, Victoria, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia; Infectious Diseases Unit, Department of General Medicine, The Royal Children's Hospital Melbourne, Victoria, Australia
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Abstract
ABSTRACT
The rapid development of genomics and other “-omics” approaches has significantly impacted how we have investigated host-pathogen interactions since the turn of the millennium. Technologies such as next-generation sequencing, stem cell biology, and high-throughput proteomics have transformed the scale and sensitivity with which we interrogate biological samples. These approaches are impacting experimental design in the laboratory and transforming clinical management in health care systems. Here, we review this area from the perspective of research on bacterial pathogens.
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Booth JS, Goldberg E, Patil SA, Greenwald BD, Sztein MB. Association between S. Typhi-specific memory CD4+ and CD8+ T responses in the terminal ileum mucosa and in peripheral blood elicited by the live oral typhoid vaccine Ty21a in humans. Hum Vaccin Immunother 2019; 15:1409-1420. [PMID: 30836838 PMCID: PMC6663141 DOI: 10.1080/21645515.2018.1564570] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
CD4+ and CD8+ T subsets are essential components of the adaptive immune system which act in concert at the site of infections to effectively protect against pathogens. Very limited data is available in humans regarding the relationship between CD4+ and CD8+ S. Typhi responsive cells in the terminal ileum mucosa (TI) and peripheral blood following Ty21a oral typhoid immunization. Here, we compared TI lamina propria mononuclear cells (LPMC) and peripheral blood CD4+ and CD8+ T memory (TM) subsets responses and their relationship by Spearman’s correlation following Ty21a immunization in volunteers undergoing routine colonoscopy. We observed that Ty21a immunization (i) influences the homing and accumulation of both CD4+ and CD8+ T cells in the TI, particularly integrin α4β7+ CCR9+ CD8+ T cells, (ii) elicits significantly higher frequencies of LPMC S. Typhi-responsive CD8+ T multifunctional (CD107a, IFNγ, IL-17A and/or MIP1β) cells than their CD4+ T counterparts, and (iii) results in the correlation of LPMC CD4+ Teffector/memory (TEM) S. Typhi responses (CD107a, IFNγ, TNFα, IL-17A and/or MIP1β) to their LPMC CD8+ TEM counterparts. Moreover, we demonstrated that these positive correlations between CD4+ and CD8+ TEM occur primarily in TI LPMC but not in PBMC, suggesting important differences in responses between the mucosal and systemic compartments following oral Ty21a immunization. This study provides the first demonstration of the correlation of S. Typhi-specific CD4+ and CD8+ TM responses in the human terminal ileum mucosa and provides valuable information regarding the generation of mucosal and systemic immune responses following oral Ty21a-immunization which might impact future vaccine design and development.
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Affiliation(s)
- Jayaum S Booth
- a Center for Vaccine Development and Global Health , University of Maryland School of Medicine , Baltimore , MD , USA.,b Department of Pediatrics , University of Maryland School of Medicine , Baltimore , MD , USA
| | - Eric Goldberg
- c Department of Medicine , University of Maryland School of Medicine , Baltimore , MD , USA.,d Division of Gastroenterology and Hepatology , University of Maryland School of Medicine , Baltimore , MD , USA
| | - Seema A Patil
- c Department of Medicine , University of Maryland School of Medicine , Baltimore , MD , USA.,d Division of Gastroenterology and Hepatology , University of Maryland School of Medicine , Baltimore , MD , USA
| | - Bruce D Greenwald
- c Department of Medicine , University of Maryland School of Medicine , Baltimore , MD , USA.,d Division of Gastroenterology and Hepatology , University of Maryland School of Medicine , Baltimore , MD , USA
| | - Marcelo B Sztein
- a Center for Vaccine Development and Global Health , University of Maryland School of Medicine , Baltimore , MD , USA.,b Department of Pediatrics , University of Maryland School of Medicine , Baltimore , MD , USA.,c Department of Medicine , University of Maryland School of Medicine , Baltimore , MD , USA
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181
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Stanaway JD, Reiner RC, Blacker BF, Goldberg EM, Khalil IA, Troeger CE, Andrews JR, Bhutta ZA, Crump JA, Im J, Marks F, Mintz E, Park SE, Zaidi AKM, Abebe Z, Abejie AN, Adedeji IA, Ali BA, Amare AT, Atalay HT, Avokpaho EFGA, Bacha U, Barac A, Bedi N, Berhane A, Browne AJ, Chirinos JL, Chitheer A, Dolecek C, El Sayed Zaki M, Eshrati B, Foreman KJ, Gemechu A, Gupta R, Hailu GB, Henok A, Hibstu DT, Hoang CL, Ilesanmi OS, Iyer VJ, Kahsay A, Kasaeian A, Kassa TD, Khan EA, Khang YH, Magdy Abd El Razek H, Melku M, Mengistu DT, Mohammad KA, Mohammed S, Mokdad AH, Nachega JB, Naheed A, Nguyen CT, Nguyen HLT, Nguyen LH, Nguyen NB, Nguyen TH, Nirayo YL, Pangestu T, Patton GC, Qorbani M, Rai RK, Rana SM, Ranabhat CL, Roba KT, Roberts NLS, Rubino S, Safiri S, Sartorius B, Sawhney M, Shiferaw MS, Smith DL, Sykes BL, Tran BX, Tran TT, Ukwaja KN, Vu GT, Vu LG, Weldegebreal F, Yenit MK, Murray CJL, Hay SI. The global burden of typhoid and paratyphoid fevers: a systematic analysis for the Global Burden of Disease Study 2017. THE LANCET. INFECTIOUS DISEASES 2019; 19:369-381. [PMID: 30792131 PMCID: PMC6437314 DOI: 10.1016/s1473-3099(18)30685-6] [Citation(s) in RCA: 395] [Impact Index Per Article: 79.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 10/17/2018] [Accepted: 11/01/2018] [Indexed: 12/11/2022]
Abstract
BACKGROUND Efforts to quantify the global burden of enteric fever are valuable for understanding the health lost and the large-scale spatial distribution of the disease. We present the estimates of typhoid and paratyphoid fever burden from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017, and the approach taken to produce them. METHODS For this systematic analysis we broke down the relative contributions of typhoid and paratyphoid fevers by country, year, and age, and analysed trends in incidence and mortality. We modelled the combined incidence of typhoid and paratyphoid fevers and split these total cases proportionally between typhoid and paratyphoid fevers using aetiological proportion models. We estimated deaths using vital registration data for countries with sufficiently high data completeness and using a natural history approach for other locations. We also estimated disability-adjusted life-years (DALYs) for typhoid and paratyphoid fevers. FINDINGS Globally, 14·3 million (95% uncertainty interval [UI] 12·5-16·3) cases of typhoid and paratyphoid fevers occurred in 2017, a 44·6% (42·2-47·0) decline from 25·9 million (22·0-29·9) in 1990. Age-standardised incidence rates declined by 54·9% (53·4-56·5), from 439·2 (376·7-507·7) per 100 000 person-years in 1990, to 197·8 (172·0-226·2) per 100 000 person-years in 2017. In 2017, Salmonella enterica serotype Typhi caused 76·3% (71·8-80·5) of cases of enteric fever. We estimated a global case fatality of 0·95% (0·54-1·53) in 2017, with higher case fatality estimates among children and older adults, and among those living in lower-income countries. We therefore estimated 135·9 thousand (76·9-218·9) deaths from typhoid and paratyphoid fever globally in 2017, a 41·0% (33·6-48·3) decline from 230·5 thousand (131·2-372·6) in 1990. Overall, typhoid and paratyphoid fevers were responsible for 9·8 million (5·6-15·8) DALYs in 2017, down 43·0% (35·5-50·6) from 17·2 million (9·9-27·8) DALYs in 1990. INTERPRETATION Despite notable progress, typhoid and paratyphoid fevers remain major causes of disability and death, with billions of people likely to be exposed to the pathogens. Although improvements in water and sanitation remain essential, increased vaccine use (including with typhoid conjugate vaccines that are effective in infants and young children and protective for longer periods) and improved data and surveillance to inform vaccine rollout are likely to drive the greatest improvements in the global burden of the disease. FUNDING Bill & Melinda Gates Foundation.
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182
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Jamka LP, Simiyu KW, Bentsi-Enchill AD, Mwisongo AJ, Matzger H, Marfin AA, Pollard AJ, Neuzil KM. Accelerating Typhoid Conjugate Vaccine Introduction: What Can Be Learned From Prior New Vaccine Introduction Initiatives? Clin Infect Dis 2019; 68:S171-S176. [PMID: 30845328 PMCID: PMC6405264 DOI: 10.1093/cid/ciy1118] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The health consequences of typhoid, including increasing prevalence of drug-resistant strains, can stress healthcare systems. While vaccination is one of the most successful and cost-effective health interventions, vaccine introduction can take years and require considerable effort. The Typhoid Vaccine Acceleration Consortium (TyVAC) employs an integrated, proactive approach to accelerate the introduction of a new typhoid conjugate vaccine to reduce the burden of typhoid in countries eligible for support from Gavi, the Vaccine Alliance. TyVAC and its partners are executing a plan, informed by prior successful vaccine introductions, and tailored to the nuances of typhoid disease and the typhoid conjugate vaccine. The iterative process detailed herein summarizes the strategy and experience gained from the first 2 years of the project.
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Affiliation(s)
- Leslie P Jamka
- Center for Vaccine Development and Global Health at the University of Maryland School of Medicine, Baltimore, MD
| | - Kenneth W Simiyu
- Center for Vaccine Development and Global Health at the University of Maryland School of Medicine, Baltimore, MD
| | - Adwoa D Bentsi-Enchill
- Department of Immunization, Vaccines and Biologicals, World Health Organization, Geneva, Switzerland
| | - Aziza J Mwisongo
- Center for Vaccine Innovation and Access, PATH, Seattle, Washington
| | - Helen Matzger
- Department of Immunization, Vaccines and Biologicals, World Health Organization, Geneva, Switzerland
| | - Anthony A Marfin
- Center for Vaccine Innovation and Access, PATH, Seattle, Washington
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Kathleen M Neuzil
- Center for Vaccine Development and Global Health at the University of Maryland School of Medicine, Baltimore, MD
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183
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Affiliation(s)
- Andrew J Pollard
- Oxford Vaccine Group, University of Oxford, and the National Institute for Health Research Oxford Biomedical Research Centre, United Kingdom
| | - Anthony A Marfin
- Center for Vaccine Innovation and Access, PATH, Seattle, Washington
| | - Kathleen M Neuzil
- Center for Vaccine Development and Global Health at the University of Maryland School of Medicine, Baltimore, MD
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184
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Abstract
BACKGROUND Contemporary incidence estimates of typhoid fever are needed to guide policy decisions and control measures and to improve future epidemiological studies. METHODS We systematically reviewed 3 databases (Ovid Medline, PubMed, and Scopus) without restriction on age, country, language, or time for studies reporting the incidence of blood culture-confirmed typhoid fever. Outbreak, travel-associated, and passive government surveillance reports were excluded. We performed a meta-analysis using a random-effects model to calculate estimates of pooled incidence, stratifying by studies that reported the incidence of typhoid fever and those that estimated incidence by using multipliers. RESULTS Thirty-three studies were included in the analysis. There were 26 study sites from 16 countries reporting typhoid cases from population-based incidence studies, and 17 sites in 9 countries used multipliers to account for underascertainment in sentinel surveillance data. We identified Africa and Asia as regions with studies showing high typhoid incidence while noting considerable variation of typhoid incidence in time and place, including in consecutive years at the same location. Overall, more recent studies reported lower typhoid incidence compared to years prior to 2000. We identified variation in the criteria for collecting a blood culture, and among multiplier studies we identified a lack of a standardization for the types of multipliers being used to estimate incidence. CONCLUSIONS Typhoid fever incidence remains high at many sites. Additional and more accurate typhoid incidence studies are needed to support country decisions about typhoid conjugate vaccine adoption. Standardization of multiplier types applied in multiplier studies is recommended.
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Affiliation(s)
| | - Chuen Yen Hong
- Centre for International Health, University of Otago, New Zealand
| | - John A Crump
- Centre for International Health, University of Otago, New Zealand
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185
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The global burden of enteric fevers in the age of typhoid-conjugate vaccines. THE LANCET. INFECTIOUS DISEASES 2019; 19:340-341. [PMID: 30792132 DOI: 10.1016/s1473-3099(19)30064-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Accepted: 12/18/2018] [Indexed: 11/23/2022]
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186
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Treanor J. Influenza Challenge and the Challenge of Drug Development. J Infect Dis 2019; 219:171-172. [DOI: 10.1093/infdis/jiy413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 06/29/2018] [Indexed: 11/13/2022] Open
Affiliation(s)
- John Treanor
- Infectious Diseases Division, Department of Medicine, University of Rochester Medical Center, New York
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187
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Moser-van der Geest N, Schibli A, Huber LC. [CME: Typhoid Fever - Clinical Manifestation, Diagnosis, Therapy and Prevention]. PRAXIS 2019; 108:937-943. [PMID: 31662103 DOI: 10.1024/1661-8157/a003319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
CME: Typhoid Fever - Clinical Manifestation, Diagnosis, Therapy and Prevention Abstract. Thypoid fever is rare in Western countries. It is, however, among the most common etiologies for febrile illness in the traveller returning from tropical areas (especially South(east) Asia and Sub-Saharan Africa). There are several signs that have been described as classical findings in typhoid fever: i) febrile temperatures with relative bradycardia, ii) eosinopenia, iii) slow defervescence, and iv) systemic manifestations (e.g. hepatitis). Diagnosis is confirmed by positive blood cultures. Pretravel vaccination and safe food and water practices can prevent typhoid fever.
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Affiliation(s)
| | - Adrian Schibli
- Abteilung für Infektiologie, Departement für Innere Medizin, Stadtspital Triemli
| | - Lars C Huber
- Klinik für Innere Medizin, Departement für Innere Medizin, Stadtspital Triemli
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188
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von Asmuth EGJ, Brockhoff HJ, Wallinga J, Visser LG. S. typhi Vi capsular polysaccharide vaccine-induced humoral immunity in travellers with immunosuppressive therapy for rheumatoid disease. J Travel Med 2019; 26:5077767. [PMID: 30137469 DOI: 10.1093/jtm/tay073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 08/18/2018] [Indexed: 12/28/2022]
Abstract
INTRODUCTION Typhoid fever is a global health problem, causing significant morbidity and mortality. Currently, the most widely used vaccine is the typhoid Vi capsular polysaccharide (Vi-PS) vaccine. While epidemiological studies on its efficacy have been performed in children in endemic countries, there are no efficacy studies evaluating its use in travel medicine. Response to vaccination may differ in travellers receiving immunosuppressive therapy. This study investigates the humoral response to Vi-PS vaccination in travellers receiving immunosuppressive therapy for rheumatoid disease. METHODS We recruited patients from the LUMC rheumatology outpatient clinic and travellers from the travel clinic who had previously received Vi-PS vaccination and also immunosuppressive therapy for rheumatoid disease. We analysed blood samples acquired from 42 patients over a period of 3 years. We estimated the length of persistence of protective titres using the survival analysis using multiple cut-off values for protection and measured titre half-life and the influence of immunosuppressive medication on titre half-life using mixed models. RESULTS Anti-Vi-PS antibody levels stayed above 10 EU/ml for a mean of 13.3 years, above 15 EU/ml for a mean of 10.1 years and above 20 EU/ml for a mean of 8.6 years after Vi-PS vaccination. Titre half-life was 7.5 years (95% CI 5.0-14.7 years, P < 0.001). No significant influence of medication on titre half-life was found. CONCLUSION Both persistence of protective antibody titres and titre half-life are longer than expected based on other studies. This warrants further study in adult volunteers, both in healthy individuals and patients suffering from rheumatoid disease.
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Affiliation(s)
- E G J von Asmuth
- Department of Infectious Diseases, LUMC, Leiden, The Netherlands
| | | | - J Wallinga
- Department of Medical Statistics and Bio-informatics, LUMC, Leiden, The Netherlands
| | - L G Visser
- Department of Infectious Diseases, LUMC, Leiden, The Netherlands
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189
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Affiliation(s)
- Dani Cohen
- Department of Epidemiology and Preventive Medicine, School of Public Health, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Khitam Muhsen
- Department of Epidemiology and Preventive Medicine, School of Public Health, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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190
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191
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Dougan G, Dowson C, Overington J. Meeting the discovery challenge of drug-resistant infections: progress and focusing resources. Drug Discov Today 2018; 24:452-461. [PMID: 30476550 DOI: 10.1016/j.drudis.2018.11.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 09/12/2018] [Accepted: 11/20/2018] [Indexed: 01/10/2023]
Abstract
Following multiple warnings from governments and health organisations, there has been renewed investment, led by the public sector, in the discovery of novel antimicrobials to meet the challenge of rising levels of drug-resistant infection, particularly in the case of resistance to antibiotics. Initiatives have also been announced to support and enable the antibiotic discovery process. In January 2018, the Medicines Discovery Catapult, UK, hosted a symposium: Next Generation Antibiotics Discovery, to consider the latest initiatives and any remaining challenges to inform and guide the international research community and better focus resources to yield a novel class of antibiotic.
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Affiliation(s)
- Gordon Dougan
- The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Cambridge, UK; The Department of Medicine, University of Cambridge, UK.
| | | | - John Overington
- Medicine Discovery Catapult, Mereside, Alderly Park, Alderly Edge, Cheshire, UK
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192
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Rijpkema S, Hockley J, Logan A, Rigsby P, Atkinson E, Jin C, Goldblatt D, Liang H, Bachtiar NS, Yang JS, Goel A, Ramasamy V, Pasetti MF, Pollard AJ. Establishment of the first International Standard for human anti-typhoid capsular Vi polysaccharide IgG. Biologicals 2018; 56:29-38. [PMID: 30201529 PMCID: PMC6238147 DOI: 10.1016/j.biologicals.2018.09.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 09/03/2018] [Indexed: 11/19/2022] Open
Abstract
Vi capsular polysaccharide (Vi) conjugate vaccines, which can prevent typhoid in infants and young children, are being developed. Comparative immunogenicity studies are facilitated by an International Standard (IS) for human anti-Vi IgG. 16/138, a pool of sera from volunteers which received either Vi conjugate vaccine or plain Vi vaccine, was assessed as an IS alongside U.S. reference reagent Vi-IgGR1, 2011. Samples were tested in a commercial ELISA (n = 7), a standardised ELISA based on biotinylated Vi (n = 7) and in-house ELISAs (n = 7). Valid estimates were obtained for the potency of all samples in the commercial ELISA, and the commutability of 16/138 and Vi-IgGR1, 2011 was evident for the commercial ELISA and in-house ELISAs based on a coating of Vi and protein. The WHO Expert Committee on Biological Standardization established 16/138 as the first IS for anti-Vi IgG with 100 IU per ampoule and assigned 163 IU per vial of Vi-IgGR1, 2011.
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Affiliation(s)
- Sjoerd Rijpkema
- Division of Bacteriology, National Institute for Biological Standards and Control, Potters Bar, Hertfordshire, EN6 3QG, United Kingdom.
| | - Jason Hockley
- Biostatistics Group, National Institute for Biological Standards and Control, Potters Bar, Hertfordshire, EN6 3QG, United Kingdom
| | - Alastair Logan
- Division of Bacteriology, National Institute for Biological Standards and Control, Potters Bar, Hertfordshire, EN6 3QG, United Kingdom
| | - Peter Rigsby
- Biostatistics Group, National Institute for Biological Standards and Control, Potters Bar, Hertfordshire, EN6 3QG, United Kingdom
| | - Eleanor Atkinson
- Biostatistics Group, National Institute for Biological Standards and Control, Potters Bar, Hertfordshire, EN6 3QG, United Kingdom
| | - Celina Jin
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - David Goldblatt
- University College London, Great Ormond Street Institute of Child Health, London, United Kingdom
| | - Haoyu Liang
- Institute for Biological Product Control, National Institute for Food and Drug Control, No.2 Tiantan Xili, Beijing, People's Republic of China
| | - Novilia S Bachtiar
- Clinical Trial Department, Surveillance & Clinical Trial Division, Bio Farma, Jl.Pasteur No.28, Bandung, Indonesia
| | - Jae Seung Yang
- Clinical Immunology, International Vaccine Institute, SNU Research Park, 1 Kwanak-Ro, Kwanak-Gu, Seoul, Republic of Korea
| | - Akshay Goel
- R&D, Biological E. Ltd, MN Park, Genome Valley, Shameerpet, Hyderabad, 500078, Telangana, India
| | - Venkatesan Ramasamy
- Quality Operations, Bharat Biotech International Ltd, Genome Valley, Shameerpet, Hyderabad, 500078, Telangana, India
| | - Marcela F Pasetti
- Center for Vaccine Development, University of Maryland Baltimore, 685 West Baltimore Street, Room 480, Baltimore, MD, USA
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
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Andrews JR, Qamar FN, Charles RC, Ryan ET. Extensively Drug-Resistant Typhoid - Are Conjugate Vaccines Arriving Just in Time? N Engl J Med 2018; 379:1493-1495. [PMID: 30332569 DOI: 10.1056/nejmp1803926] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Jason R Andrews
- From the Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, CA (J.R.A.); the Department of Pediatric and Child Health, the Aga Khan University, Karachi, Pakistan (F.N.Q.); and the Division of Infectious Diseases, Massachusetts General Hospital (R.C.C., E.T.R.), the Department of Medicine, Harvard Medical School (R.C.C., E.T.R.), and the Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health (E.T.R.) - all in Boston
| | - Farah N Qamar
- From the Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, CA (J.R.A.); the Department of Pediatric and Child Health, the Aga Khan University, Karachi, Pakistan (F.N.Q.); and the Division of Infectious Diseases, Massachusetts General Hospital (R.C.C., E.T.R.), the Department of Medicine, Harvard Medical School (R.C.C., E.T.R.), and the Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health (E.T.R.) - all in Boston
| | - Richelle C Charles
- From the Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, CA (J.R.A.); the Department of Pediatric and Child Health, the Aga Khan University, Karachi, Pakistan (F.N.Q.); and the Division of Infectious Diseases, Massachusetts General Hospital (R.C.C., E.T.R.), the Department of Medicine, Harvard Medical School (R.C.C., E.T.R.), and the Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health (E.T.R.) - all in Boston
| | - Edward T Ryan
- From the Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, CA (J.R.A.); the Department of Pediatric and Child Health, the Aga Khan University, Karachi, Pakistan (F.N.Q.); and the Division of Infectious Diseases, Massachusetts General Hospital (R.C.C., E.T.R.), the Department of Medicine, Harvard Medical School (R.C.C., E.T.R.), and the Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health (E.T.R.) - all in Boston
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194
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Riddle M, Chen W, Kirkwood C, MacLennan C. Update on vaccines for enteric pathogens. Clin Microbiol Infect 2018; 24:1039-1045. [DOI: 10.1016/j.cmi.2018.06.023] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 06/17/2018] [Accepted: 06/19/2018] [Indexed: 12/12/2022]
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195
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Selgelid MJ, Jamrozik E. Ethical challenges posed by human infection challenge studies in endemic settings. Indian J Med Ethics 2018; 3:263-266. [PMID: 30473497 PMCID: PMC6785344 DOI: 10.20529/ijme.2018.073] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Human infection challenge studies (HCS) involve intentionally infecting research participants with pathogens, often with the ultimate aim of developing new interventions against infectious diseases. Despite ethical concerns about research involving vulnerable populations, there are both scientific and ethical reasons to consider conducting more HCS in low- and middle-income countries where neglected diseases are often endemic. HCS researchers can reduce the risks to participants (and the risks of transmission from participants to others) by controlling multiple factors (eg those related to the laboratory environment, participant selection, the pathogen, and the timing of treatment); but HCS nonetheless raise important ethical issues, some of which may be particularly pertinent to HCS in endemic settings. This article provides background on HCS in general, as well as recent HCS in low- and middle-income countries, and an overview of the ethical issues associated with HCS in endemic settings.
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Affiliation(s)
| | - Euzebiusz Jamrozik
- Monash Bioethics Centre, Monash University, Melbourne, AUSTRALIA, Department of General Medicine, Royal Melbourne Hospital, Melbourne, AUSTRALIA.,
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196
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Awofisayo-Okuyelu A, McCarthy N, Mgbakor I, Hall I. Incubation period of typhoidal salmonellosis: a systematic review and meta-analysis of outbreaks and experimental studies occurring over the last century. BMC Infect Dis 2018; 18:483. [PMID: 30261843 PMCID: PMC6161394 DOI: 10.1186/s12879-018-3391-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 09/17/2018] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Salmonella Typhi is a human pathogen that causes typhoid fever. It is a major cause of morbidity and mortality in developing countries and is responsible for several outbreaks in developed countries. Studying certain parameters of the pathogen, such as the incubation period, provides a better understanding of its pathophysiology and its characteristics within a population. Outbreak investigations and human experimental studies provide an avenue to study these relevant parameters. METHODS In this study, the authors have undertaken a systematic review of outbreak investigation reports and experimental studies, extracted reported data, tested for heterogeneity, identified subgroups of studies with limited evidence of heterogeneity between them and identified factors that may contribute to the distribution of incubation period. Following identification of relevant studies, we extracted both raw and summary incubation data. We tested for heterogeneity by deriving the value of I2 and conducting a KS-test to compare the distribution between studies. We performed a linear regression analysis to identify the factors associated with incubation period and using the resulting p-values from the KS-test, we conducted a hierarchical cluster analysis to classify studies with limited evidence of heterogeneity into subgroups. RESULTS We identified thirteen studies to be included in the review and extracted raw incubation period data from eleven. The value of I2 was 84% and the proportion of KS test p-values that were less than 0.05 was 63.6% indicating high heterogeneity not due to chance. We identified vaccine history and attack rates as factors that may be associated with incubation period, although these were not significant in the multivariable analysis (p-value: 0.1). From the hierarchical clustering analysis, we classified the studies into five subgroups. The mean incubation period of the subgroups ranged from 9.7 days to 21.2 days. Outbreaks reporting cases with previous vaccination history were clustered in a single subgroup and reported the longest incubation period. CONCLUSIONS We identified attack rate and previous vaccination as possible associating factors, however further work involving analyses of individual patient data and developing mathematical models is needed to confirm these as well as examine additional factors that have not been included in our study.
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Affiliation(s)
- Adedoyin Awofisayo-Okuyelu
- NIHR Health Protection Research Unit in Gastrointestinal Infection, University of Liverpool, Liverpool, UK
- Department of Zoology, University of Oxford, Oxford, UK
| | - Noel McCarthy
- NIHR Health Protection Research Unit in Gastrointestinal Infection, University of Liverpool, Liverpool, UK
- Department of Zoology, University of Oxford, Oxford, UK
- Warwick Medical School, University of Warwick, Warwick, UK
| | - Ifunanya Mgbakor
- Warwick Medical School, University of Warwick, Warwick, UK
- Epidemiology, Strategic Information and Health Systems Strengthening Branch, Nigeria Office, Lagos, Nigeria
| | - Ian Hall
- School of Mathematics, University of Manchester, Manchester, UK
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197
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Computing threshold antibody levels of protection in vaccine clinical trials: An assessment of methodological bias. PLoS One 2018; 13:e0202517. [PMID: 30192787 PMCID: PMC6128451 DOI: 10.1371/journal.pone.0202517] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 08/03/2018] [Indexed: 11/21/2022] Open
Abstract
In the development of new vaccines, understanding the level of vaccine-induced antibody that is sufficient to protect against disease can simplify and expedite the development and licensing process. If there is an accepted threshold antibody level that is indicative of protection, then smaller trials measuring antibody concentration alone can be conducted to test new vaccines, instead of large efficacy studies powered on clinical outcomes. Commonly, threshold levels of protective antibody are determined from clinical efficacy trials in which clinical endpoints are measured on everyone and a small subset of participants have antibody concentrations measured. The proportion of participants with antibody below a threshold in each group in the immunogenicity subset can be compared to the proportions with disease in each group in the larger trial to find an appropriate threshold. Mathematically, this method seeks to compute an absolute threshold whereby antibody above the threshold provides complete, sterilizing immunity. However, in practice it is often understood that such thresholds may only be indicative of a relative degree of protection rather than an absolute one. Although this approach is common, the accuracy of such methods when the underlying mathematical assumptions do not hold true, has never been tested. We simulated data from clinical trial scenarios under varying assumptions of vaccine efficacy and calculated antibody thresholds of protection. We estimated the bias in the calculated thresholds derived from each scenario and showed that in many situations this method produces inflated estimates of thresholds, particularly if a vaccine induces high levels of antibody or when the underlying assumption of sterilizing immunity is violated.
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198
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Typhoid fever in Santiago, Chile: Insights from a mathematical model utilizing venerable archived data from a successful disease control program. PLoS Negl Trop Dis 2018; 12:e0006759. [PMID: 30188904 PMCID: PMC6143279 DOI: 10.1371/journal.pntd.0006759] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 09/18/2018] [Accepted: 08/16/2018] [Indexed: 12/04/2022] Open
Abstract
Typhoid fever is endemic in many developing countries. In the early 20th century, newly industrializing countries including the United States successfully controlled typhoid as water treatment (chlorination/sand filtration) and improved sanitation became widespread. Enigmatically, typhoid remained endemic through the 1980s in Santiago, Chile, despite potable municipal water and widespread household sanitation. Data were collected across multiple stages of endemicity and control in Santiago, offering a unique resource for gaining insight into drivers of transmission in modern settings. We developed an individual-based mathematical model of typhoid transmission, with model components including distinctions between long-cycle and short-cycle transmission routes. Data used to fit the model included the prevalence of chronic carriers, seasonality, longitudinal incidence, and age-specific distributions of typhoid infection and disease. Our model captured the dynamics seen in Santiago across endemicity, vaccination, and environmental control. Both vaccination and diminished exposure to seasonal amplified long-cycle transmission contributed to the observed declines in typhoid incidence, with the vaccine estimated to elicit herd effects. Vaccines are important tools for controlling endemic typhoid, with even limited coverage eliciting herd effects in this setting. Removing the vehicles responsible for amplified long-cycle transmission and assessing the role of chronic carriers in endemic settings are additional key elements in designing programs to achieve accelerated control of endemic typhoid. Typhoid fever was successfully controlled in Santiago, Chile, after a series of interventions including vaccination with a live oral vaccine (Ty21a), and an environmental sanitation improvement, when a ban was put on the irrigation of salad vegetable crops with untreated sewage. Data collected during this period inform seasonality, age distribution and longitudinal trends of disease. We developed an individual-based, mathematical model to both simulate the dynamics of typhoid seen in Santiago, as well as to investigate relative impacts of the vaccine and sanitation interventions. We found that herd immunity resulted from field trials of the Ty21a vaccine and that chronic carriers were a likely driver of sustained transmission at low incidence levels. Modeling typhoid fever in areas that have demonstrated successful control provides insight for control strategies in modern settings.
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199
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Bhutta ZA, Zaidi AKM, Pangestu T. Reducing Typhoid Burden within a Generation. Am J Trop Med Hyg 2018; 99:1-3. [PMID: 30047372 PMCID: PMC6128364 DOI: 10.4269/ajtmh.18-0500] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Accepted: 06/12/2018] [Indexed: 02/06/2023] Open
Affiliation(s)
- Zulfiqar A. Bhutta
- Centre for Global Child Health, The Hospital for Sick Children, Toronto, Canada
- Dalla Lana School of Public Health, University of Toronto, Toronto, Canada
- Center of Excellence in Women and Child Health, The Aga Khan University, Karachi, Pakistan
| | - Anita K. M. Zaidi
- Vaccine Development and Surveillance, Bill & Melinda Gates Foundation, Seattle, Washigton
- Enteric and Diarrheal Diseases, Bill & Melinda Gates Foundation, Seattle, Washigton
| | - Tikki Pangestu
- Visiting Professor, Lee Kuan Yew School of Public Policy, National University of Singapore, Singapore, Singapore
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200
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Andrews JR, Baker S, Marks F, Alsan M, Garrett D, Gellin BG, Saha SK, Qamar FN, Yousafzai MT, Bogoch II, Antillon M, Pitzer VE, Kim JH, John J, Gauld J, Mogasale V, Ryan ET, Luby SP, Lo NC. Typhoid conjugate vaccines: a new tool in the fight against antimicrobial resistance. THE LANCET. INFECTIOUS DISEASES 2018; 19:e26-e30. [PMID: 30170987 DOI: 10.1016/s1473-3099(18)30350-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 05/10/2018] [Accepted: 05/17/2018] [Indexed: 10/28/2022]
Abstract
Typhoid fever is an acute systemic infectious disease responsible for an estimated 12-20 million illnesses and over 150 000 deaths annually. In March, 2018, a new recommendation was issued by WHO for the programmatic use of typhoid conjugate vaccines in endemic countries. Health economic analyses of typhoid vaccines have informed funding decisions and national policies regarding vaccine rollout. However, by focusing only on averted typhoid cases and their associated costs, traditional cost-effectiveness analyses might underestimate crucial benefits of typhoid vaccination programmes, because the potential effect of typhoid vaccines on the treatment of patients with non-specific acute febrile illnesses is not considered. For every true case of typhoid fever, three to 25 patients without typhoid disease are treated with antimicrobials unnecessarily, conservatively amounting to more than 50 million prescriptions per year. Antimicrobials for suspected typhoid might therefore be an important selective pressure for the emergence and spread of antimicrobial resistance globally. We propose that large-scale, more aggressive typhoid vaccination programmes-including catch-up campaigns in children up to 15 years of age, and vaccination in lower incidence settings-have the potential to reduce the overuse of antimicrobials and thereby reduce antimicrobial resistance in many bacterial pathogens. Funding bodies and national governments must therefore consider the potential for broad reductions in antimicrobial use and resistance in decisions related to the rollout of typhoid conjugate vaccines.
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Affiliation(s)
- Jason R Andrews
- Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, CA, USA.
| | - Stephen Baker
- Department of Medicine, University of Cambridge, Cambridge, UK
| | - Florian Marks
- Department of Medicine, University of Cambridge, Cambridge, UK; Epidemiology Unit, International Vaccine Institute, Seoul, South Korea
| | - Marcella Alsan
- Center for Health Policy and the Center for Primary Care and Outcomes Research, Stanford University, Stanford, CA, USA
| | | | | | - Samir K Saha
- Department of Microbiology, Bangladesh Institute of Child Health, Dhaka Shishu Hospital, Dhaka, Bangladesh
| | - Farah Naz Qamar
- Department of Paediatrics and Child Health, Aga Khan University, Karachi, Pakistan
| | | | - Isaac I Bogoch
- Department of Medicine, University of Toronto, Toronto, Canada
| | - Marina Antillon
- Center for Health Economics Research and Modeling Infectious Diseases, University of Antwerp, Belgium
| | - Virginia E Pitzer
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, USA
| | - Jong-Hoon Kim
- Epidemiology Unit, International Vaccine Institute, Seoul, South Korea
| | - Jacob John
- Department of Community Health, Christian Medical College, Vellore, Tamil Nadu, India
| | | | - Vittal Mogasale
- Policy and Economic Research Department, Development and Delivery Unit, International Vaccine Institute, Seoul, South Korea
| | - Edward T Ryan
- Division of Infectious Diseases, Massachusetts General Hospital, Harvard University, Boston, MA, USA
| | - Stephen P Luby
- Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Nathan C Lo
- Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, CA, USA
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