The Experts below are selected from a list of 16626 Experts worldwide ranked by ideXlab platform
John Wain - One of the best experts on this subject based on the ideXlab platform.
-
risk factors for the development of severe Typhoid Fever in vietnam
BMC Infectious Diseases, 2014Co-Authors: Ha Vinh, John Wain, Nguyen Tran Chinh, Corinne N Thompson, Christopher M Parry, Le Thi Phuong, Tran Tinh HienAbstract:Background: Typhoid Fever is a systemic infection caused by the bacterium Salmonella enterica serovar Typhi. Age, sex, prolonged duration of illness, and infection with an antimicrobial resistant organism have been proposed risk factors for the development of severe disease or fatality in Typhoid Fever. Methods: We analysed clinical data from 581 patients consecutively admitted with culture confirmed Typhoid Fever to two hospitals in Vietnam during two periods in 1993–1995 and 1997–1999. These periods spanned a change in the antimicrobial resistance phenotypes of the infecting organisms i.e. fully susceptible to standard antimicrobials, resistance to chloramphenicol, ampicillin and trimethoprim-sulphamethoxazole (multidrug resistant, MDR), and intermediate susceptibility to ciprofloxacin (nalidixic acid resistant). Age, sex, duration of illness prior to admission, hospital location and the presence of MDR or intermediate ciprofloxacin susceptibility in the infecting organism were examined by logistic regression analysis to identify factors independently associated with severe Typhoid at the time of hospital admission. Results: The prevalence of severe Typhoid was 15.5% (90/581) and included: gastrointestinal bleeding (43; 7.4%); hepatitis (29; 5.0%); encephalopathy (16; 2.8%); myocarditis (12; 2.1%); intestinal perforation (6; 1.0%); haemodynamic shock (5; 0.9%), and death (3; 0.5%). Severe disease was more common with increasing age, in those with a longer duration of illness and in patients infected with an organism exhibiting intermediate susceptibility to ciprofloxacin. Notably an MDR phenotype was not associated with severe disease. Severe disease was independently associated with infection with an organism with an intermediate susceptibility to ciprofloxacin (AOR 1.90; 95% CI 1.18-3.07; p = 0.009) and male sex (AOR 1.61 (1.00-2.57; p = 0.035). Conclusions: In this group of patients hospitalised with Typhoid Fever infection with an organism with intermediate susceptibility to ciprofloxacin was independently associated with disease severity. During this period many patients were being treated with fluoroquinolones prior to hospital admission. Ciprofloxacin and ofloxacin should be used with caution in patients infected with S. Typhi that have intermediate susceptibility to ciprofloxacin.
-
Specimens and culture media for the laboratory diagnosis of Typhoid Fever.
Journal of infection in developing countries, 2008Co-Authors: John Wain, Phan Van Be Bay, Nguyen M. Duong, Vo Anh Ho, Truong Thi Hien, Ha Vinh, To S Diep, Amanda L. Walsh, Jeremy FarrarAbstract:BACKGROUND Culture of S. Typhi is necessary for the definitive diagnosis of Typhoid Fever and provides isolates for antibiotic susceptibility testing and epidemiological studies. However, current methods are not fully optimised and sourcing culture media and bottles for culture media may be problematic. METHODOLOGY In two hospital laboratories in Viet Nam, comparisons of media for blood and stool culture were conducted. The effect of the volume of blood or stool on culture positivity rate was examined and direct plating of the blood buffy coat was trialed. RESULTS For 148 suspected Typhoid Fever cases, ox bile broth (58 positive) and brain-heart infusion broth containing saponin (63 positive), performed equally well. For 69 confirmed adult Typhoid Fever cases, large-volume (15 ml) blood culture gave the same sensitivity as 1 ml of bone marrow culture. For 44 confirmed Typhoid Fever cases, the direct plating of the buffy coat was positive in 28 cases. For 263 positive stool cultures, selenite F and selenite mannitol performed equally well and culturing 2 g rather than 1g increased the isolation rate by 10.5%. CONCLUSIONS For the diagnosis of Typhoid Fever by blood culture the medium should be a rich nutrient broth containing a lysing agent. In adults 1 ml bone marrow or 15 ml blood culture gave similar results. Where isolates are needed for susceptibility testing or epidemiological studies, but resources for culture are scarce, direct plating of the blood buffy coat can be used with a 50% fall in sensitivity compared to standard blood culture.
-
Original Article Specimens and culture media for the laboratory diagnosis of Typhoid Fever
2008Co-Authors: John Wain, Nguyen M. Duong, Truong Thi Hien, Ha Vinh, To S Diep, Amanda L. Walsh, Phan Van, Be Bay, Jeremy FarrarAbstract:Background: Culture of S. Typhi is necessary for the definitive diagnosis of Typhoid Fever and provides isolates for antibiotic susceptibility testing and epidemiological studies. However, current methods are not fully optimised and sourcing culture media and bottles for culture media may be problematic. Methodology: In two hospital laboratories in Viet Nam, comparisons of media for blood and stool culture were conducted. The effect of the volume of blood or stool on culture positivity rate was examined and direct plating of the blood buffy coat was trialed. Results: For 148 suspected Typhoid Fever cases, ox bile broth (58 positive) and brain-heart infusion broth containing saponin (63 positive), performed equally well. For 69 confirmed adult Typhoid Fever cases, large-volume (15ml) blood culture gave the same sensitivity as 1 ml of bone marrow culture. For 44 confirmed Typhoid Fever cases, the direct plating of the buffy coat was positive in 28 cases. For 263 positive stool cultures, selenite F and selenite mannitol performed equally well and culturing 2 g rather than 1g increased the isolation rate by 10.5%. Conclusions: For the diagnosis of Typhoid Fever by blood culture the medium should be a rich nutrient broth containing a lysing agent. In adults 1 ml bone marrow or 15 ml blood culture gave similar results. Where isolates are needed for susceptibility testing or epidemiological studies, but resources for culture are scarce, direct plating of the blood buffy coat can be used with a 50 % fall in sensitivity compared t
-
serology of Typhoid Fever in an area of endemicity and its relevance to diagnosis
Journal of Clinical Microbiology, 2001Co-Authors: Deborah House, Ha Vinh, To S Diep, John Wain, Nguyen Tran Chinh, Phan Van Be Bay, Minh Duc, Christopher M ParryAbstract:Currently, the laboratory diagnosis of Typhoid Fever is dependent upon either the isolation of Salmonella enterica subsp. enterica serotype Typhi from a clinical sample or the detection of raised titers of agglutinating serum antibodies against the lipopolysaccharide (LPS) (O) or flagellum (H) antigens of serotype Typhi (the Widal test). In this study, the serum antibody responses to the LPS and flagellum antigens of serotype Typhi were investigated with individuals from a region of Vietnam in which Typhoid is endemic, and their usefulness for the diagnosis of Typhoid Fever was evaluated. The antibody responses to both antigens were highly variable among individuals infected with serotype Typhi, and elevated antibody titers were also detected in a high proportion of serum samples from healthy subjects from the community. In-house enzyme-linked immunosorbent assays (ELISAs) for the detection of specific classes of anti-LPS and antiflagellum antibodies were compared with other serologically based tests for the diagnosis of Typhoid Fever (Widal TO and TH, anti-serotype Typhi immunoglobulin M [IgM] dipstick, and IDeaL TUBEX). At a specificity of ≥0.93, the sensitivities of the different tests were 0.75, 0.55, and 0.52 for the anti-LPS IgM, IgG, and IgA ELISAs, respectively; 0.28 for the antiflagellum IgG ELISA; 0.47 and 0.32 for the Widal TO and TH tests, respectively; and 0.77 for the anti-serotype Typhi IgM dipstick assay. The specificity of the IDeaL TUBEX was below 0.90 (sensitivity, 0.87; specificity, 0.76). The serological assays based on the detection of IgM antibodies against either serotype Typhi LPS (ELISA) or whole bacteria (dipstick) had a significantly higher sensitivity than the Widal TO test when used with a single acute-phase serum sample (P ≤ 0.007). These tests could be of use for the diagnosis of Typhoid Fever in patients who have clinical Typhoid Fever but are culture negative or in regions where bacterial culturing facilities are not available.
Werner Troesken - One of the best experts on this subject based on the ideXlab platform.
-
Typhoid Fever, Water Quality, and Human Capital Formation
Journal of Economic History, 2016Co-Authors: Brian Beach, Joseph Ferrie, Martin Saavedra, Werner TroeskenAbstract:New water purification technologies led to large mortality declines by helping eliminate Typhoid Fever and other waterborne diseases. We examine how this affected human capital formation using early-life Typhoid fatality rates to proxy for water quality. We merge city-level data to individuals linked between the 1900 and 1940 Censuses. Eliminating early-life exposure to Typhoid Fever increased later-life earnings by one percent and educational attainment by one month. Instrumenting for Typhoid Fever using Typhoid rates from cities that lie upstream produces results nine times larger. The increase in earnings from eliminating Typhoid Fever more than offset the cost of elimination.
-
Typhoid Fever water quality and human capital formation
Social Science Research Network, 2014Co-Authors: Brian Beach, Joseph Ferrie, Martin Saavedra, Werner TroeskenAbstract:Investment in water purification technologies led to large mortality declines by helping eradicate Typhoid Fever and other waterborne diseases. This paper seeks to understand how these technologies affected human capital formation. We use Typhoid fatality rates during early life as a proxy for water quality. To carry out the analysis, city-level data are merged with a unique dataset linking individuals between the 1900 and 1940 censuses. Parametric and semi-parametric estimates suggest that eradicating early-life exposure to Typhoid Fever would have increased earnings in later life by 1% and increased educational attainment by one month. Instrumenting for Typhoid Fever using the Typhoid rates from cities that lie upstream produces similar results. A simple cost-benefit analysis indicates that the increase in earnings from eradicating Typhoid Fever was more than sufficient to offset the costs of eradication.Institutional subscribers to the NBER working paper series, and residents of developing countries may download this paper without additional charge at www.nber.org.
-
Typhoid Fever water quality and human capital formation
National Bureau of Economic Research, 2014Co-Authors: Brian Beach, Joseph Ferrie, Martin Saavedra, Werner TroeskenAbstract:Investment in water purification technologies led to large mortality declines by helping eradicate Typhoid Fever and other waterborne diseases. This paper seeks to understand how these technologies affected human capital formation. We use Typhoid fatality rates during early life as a proxy for water quality. To carry out the analysis, city-level data are merged with a unique dataset linking individuals between the 1900 and 1940 censuses. Parametric and semi-parametric estimates suggest that eradicating early-life exposure to Typhoid Fever would have increased earnings in later life by 1% and increased educational attainment by one month. Instrumenting for Typhoid Fever using the Typhoid rates from cities that lie upstream produces similar results. A simple cost-benefit analysis indicates that the increase in earnings from eradicating Typhoid Fever was more than sufficient to offset the costs of eradication.
John A Crump - One of the best experts on this subject based on the ideXlab platform.
-
introductory article on global burden and epidemiology of Typhoid Fever
American Journal of Tropical Medicine and Hygiene, 2018Co-Authors: Amruta Radhakrishnan, Eric D. Mintz, Daina Als, John A Crump, Jefferey Stanaway, Robert F Breiman, Zulfiqar A BhuttaAbstract:This article is the introduction to a 12-paper supplement on global trends in Typhoid Fever. The Tackling Typhoid (T2) project was initiated in 2015 to synthesize the existing body of literature on Typhoidal salmonellae and study national and regional Typhoid Fever trends. In addition to a global systematic review, eight case studies were undertaken to examine Typhoid and paraTyphoid Fever trends in endemic countries alongside changes in relevant contextual factors. Incidence variations exist both within and between regions with large subnational differences as well, suggesting that public health changes impacting Typhoid and paraTyphoid Fevers in one setting may not have similar impacts in another. This supplement also brings to light the lack of national Typhoid Fever surveillance systems, inconsistencies in diagnostics, and the lack of Typhoid Fever associated morbidity and mortality data in many countries, making it difficult to accurately quantify and track burden of disease. To better understand Typhoid Fever there is a need for more high-quality data from resource-poor settings. The implementation of Typhoid surveillance systems alongside the transition to blood-culture confirmation of cases, where possible, would aid in the improvement of data quality in low-income settings. The following supplement includes the results of our global systematic review, eight-country case study articles, a qualitative article informed by semistructured interviews, and a conclusion article on potential ways forward for Typhoid control.
-
Typhoid Fever way forward
American Journal of Tropical Medicine and Hygiene, 2018Co-Authors: Eric D. Mintz, John A Crump, Robert F Breiman, Zulfiqar A Bhutta, Robert E. Black, Stephen P Luby, Michelle F Gaffey, Duncan A Steele, Myron M LevineAbstract:The Tackling Typhoid supplement shows that Typhoid Fever continues to be a problem globally despite socioeconomic gains in certain settings. Morbidity remains high in many endemic countries, notably in sub-Saharan Africa and South Asia. In addition, antimicrobial resistance is a growing issue that poses a challenge for clinical management. The findings from this supplement revealed that outside of high-income countries, there were few reliable population-based estimates of Typhoid and paraTyphoid Fever derived from surveillance systems. This indicates the need for monitoring systems that can also characterize the effectiveness of interventions, particularly in low- and middle-income settings. The country case studies indicated that gains in economic conditions, education, and environmental health may be associated with reductions in Typhoid Fever burden. Over the study period, the effect is mainly notable in countries with higher baseline levels of economic development, female literacy, and investments in public sanitation. High burden countries must continue to invest in strategies at the local level to address environmental factors such as access to safe drinking water and improved public sanitation that are known to interrupt transmission or diminish the risk of acquiring Typhoid. Developing more effective vaccines and incorporating appropriate immunization strategies that target populations with the greatest risk could potentially alleviate disease burden.
-
Updating and refining estimates of Typhoid Fever burden for public health action
2016Co-Authors: John A CrumpAbstract:Efforts to estimate the global burden of Typhoid Fever can be traced to a meeting of the Pan American Health Organization in 1984 and publication of the outcome in 1986.1 Although an important first step, the 1984 study was recognised as having a number of limitations including provision of scanty methodological detail, the availability of few source data, exclusion of China from the estimate, and lack of consideration of the age distribution of Typhoid Fever. Subsequently the global Typhoid burden was re-estimated for the year 2000, accounting for growth of the global population, new Typhoid Fever incidence data from population-based studies and the control groups of vaccine trials, advances in the understanding of the age distribution of Typhoid Fever and its relation to force of infection, adjustment for blood culture sensitivity, and formalisation of methods for assessment of disease burden.2 Since 2000, an updated review of population-based studies of Typhoid Fever incidence and data from notifiable disease reports from countries with advanced surveillance systems has been published.3 Incorporating these data, the Institute for Health Metrics and Evaluation (IHME) added their first estimate of disability and death associated with Typhoid and paraTyphoid Fevers in aggregate to the Global Burden of Disease (GBD) 2010 project.4,
-
the global burden of Typhoid Fever
Bulletin of The World Health Organization, 2004Co-Authors: John A Crump, Stephen P Luby, Eric D. MintzAbstract:OBJECTIVE: To use new data to make a revised estimate of the global burden of Typhoid Fever, an accurate understanding of which is necessary to guide public health decisions for disease control and prevention efforts. METHODS: Population-based studies using confirmation by blood culture of Typhoid Fever cases were sought by computer search of the multilingual scientific literature. Where there were no eligible studies, data were extrapolated from neighbouring countries and regions. Age-incidence curves were used to model rates measured among narrow age cohorts to the general population. One-way sensitivity analysis was performed to explore the sensitivity of the estimate to the assumptions. The burden of paraTyphoid Fever was derived by a proportional method. FINDINGS: A total of 22 eligible studies were identified. Regions with high incidence of Typhoid Fever (>100/100,000 cases/year) include south-central Asia and south-eastAsia. Regions of medium incidence (10-100/100,000 cases/year) include the rest of Asia, Africa, Latin America and the Caribbean, and Oceania, except for Australia and New Zealand. Europe, North America, and the rest of the developed world have low incidence of Typhoid Fever (<10/100,000 cases/year). We estimate that Typhoid Fever caused 21,650,974 illnesses and 216,510 deaths during 2000 and that paraTyphoid Fever caused 5,412,744 illnesses. CONCLUSION: New data and improved understanding of Typhoid Fever epidemiology enabled us to refine the global Typhoid burden estimate, which remains considerable. More detailed incidence studies in selected countries and regions, particularly Africa, are needed to further improve the estimate.
-
estimating the incidence of Typhoid Fever and other febrile illnesses in developing countries
Emerging Infectious Diseases, 2003Co-Authors: John A Crump, Stephen P Luby, Fouad G Youssef, Momtaz O Wasfy, Josefa M Rangel, Maha Taalat, Said Oun, Frank MahoneyAbstract:To measure the incidence of Typhoid Fever and other febrile illnesses in Bilbeis District, Egypt, we conducted a household survey to determine patterns of health seeking among persons with Fever. Then we established surveillance for 4 months among a representative sample of health providers who saw febrile patients. Health providers collected epidemiologic information and blood (for culture and serologic testing) from eligible patients. After adjusting for the provider sampling scheme, test sensitivity, and seasonality, we estimated that the incidence of Typhoid Fever was 13/100,000 persons per year, and the incidence of brucellosis was 18/100,000 persons per year in the district. This surveillance tool could have wide applications for surveillance for febrile illness in developing countries.
Zulfiqar A Bhutta - One of the best experts on this subject based on the ideXlab platform.
-
introductory article on global burden and epidemiology of Typhoid Fever
American Journal of Tropical Medicine and Hygiene, 2018Co-Authors: Amruta Radhakrishnan, Eric D. Mintz, Daina Als, John A Crump, Jefferey Stanaway, Robert F Breiman, Zulfiqar A BhuttaAbstract:This article is the introduction to a 12-paper supplement on global trends in Typhoid Fever. The Tackling Typhoid (T2) project was initiated in 2015 to synthesize the existing body of literature on Typhoidal salmonellae and study national and regional Typhoid Fever trends. In addition to a global systematic review, eight case studies were undertaken to examine Typhoid and paraTyphoid Fever trends in endemic countries alongside changes in relevant contextual factors. Incidence variations exist both within and between regions with large subnational differences as well, suggesting that public health changes impacting Typhoid and paraTyphoid Fevers in one setting may not have similar impacts in another. This supplement also brings to light the lack of national Typhoid Fever surveillance systems, inconsistencies in diagnostics, and the lack of Typhoid Fever associated morbidity and mortality data in many countries, making it difficult to accurately quantify and track burden of disease. To better understand Typhoid Fever there is a need for more high-quality data from resource-poor settings. The implementation of Typhoid surveillance systems alongside the transition to blood-culture confirmation of cases, where possible, would aid in the improvement of data quality in low-income settings. The following supplement includes the results of our global systematic review, eight-country case study articles, a qualitative article informed by semistructured interviews, and a conclusion article on potential ways forward for Typhoid control.
-
Typhoid Fever way forward
American Journal of Tropical Medicine and Hygiene, 2018Co-Authors: Eric D. Mintz, John A Crump, Robert F Breiman, Zulfiqar A Bhutta, Robert E. Black, Stephen P Luby, Michelle F Gaffey, Duncan A Steele, Myron M LevineAbstract:The Tackling Typhoid supplement shows that Typhoid Fever continues to be a problem globally despite socioeconomic gains in certain settings. Morbidity remains high in many endemic countries, notably in sub-Saharan Africa and South Asia. In addition, antimicrobial resistance is a growing issue that poses a challenge for clinical management. The findings from this supplement revealed that outside of high-income countries, there were few reliable population-based estimates of Typhoid and paraTyphoid Fever derived from surveillance systems. This indicates the need for monitoring systems that can also characterize the effectiveness of interventions, particularly in low- and middle-income settings. The country case studies indicated that gains in economic conditions, education, and environmental health may be associated with reductions in Typhoid Fever burden. Over the study period, the effect is mainly notable in countries with higher baseline levels of economic development, female literacy, and investments in public sanitation. High burden countries must continue to invest in strategies at the local level to address environmental factors such as access to safe drinking water and improved public sanitation that are known to interrupt transmission or diminish the risk of acquiring Typhoid. Developing more effective vaccines and incorporating appropriate immunization strategies that target populations with the greatest risk could potentially alleviate disease burden.
-
cost of illness due to Typhoid Fever in five asian countries
Tropical Medicine & International Health, 2011Co-Authors: Christine Poulos, Zulfiqar A Bhutta, John D Clemens, Arthorn Riewpaiboon, John F Stewart, S Guh, Magdarina D Agtini, Dang Duc Anh, Dong Baiqing, Dipika SurAbstract:Summary objective To generate community-based estimates of the public (paid by the government) and private (paid by households) costs of blood culture-confirmed Typhoid Fever in Hechi, China; North Jakarta, Indonesia; Kolkata, India; Karachi, Pakistan and Hue, Vietnam. methods To measure out-of-pocket costs of illness and lost earnings, families with culture-proven cases were surveyed 7, 14 and 90 days after onset of illness. Public costs of treatment were measured at local health facilities using a micro costing (bottom-up) method. results The costs of hospitalized cases ranged from USD 129 in Kolkata to USD 432 in North Jakarta (hospitalization rates varied from 2% in Kolkata to 40% in Hechi) and the costs of non-hospitalized cases ranged from USD 13 in Kolkata to USD 67 in Hechi. Where costs were highest (Hechi, North Jakarta and Karachi), the bulk of the costs of hospitalized cases was borne by families, comprising up to 15% of annual household income. conclusion Although these estimates may understate true costs due to the fact that higher quality treatment may have been provided earlier-than-usual, this multi-country community-based study contributes to evidence on the public and private costs of Typhoid Fever in developing countries. These cost estimates were used in a cost-effectiveness analysis of Typhoid vaccines and will help policymakers respond to World Health Organization’s updated Typhoid Fever immunization recommendations.
-
Typhoid Fever in children some epidemiological considerations from karachi pakistan
International Journal of Infectious Diseases, 2006Co-Authors: Fahad Javaid Siddiqui, Fauziah Rabbani, Rumina Hasan, Shaikh Qamaruddin Nizami, Zulfiqar A BhuttaAbstract:Summary Background The morbidity of Typhoid Fever is highest in Asia with 93% of global episodes occurring in this region. Southeast Asia has an estimated incidence of 110cases/100000 population, which is the third highest incidence rate for any region. Pakistan falls into this region. There is also a considerable seasonal variation of Typhoid Fever, carrying significant public health importance. Children are worst affected. Population-based data from Pakistan are scarce. Methods From June 1999 to December 2001 a fortnightly surveillance system was established in two squatter settlements in Karachi, Pakistan, with two study centers, each staffed by a doctor and five community health workers. Cases of continuous high-grade Fever for three or more days were referred to these centers and screened clinically. Blood culture and Typhidot ® tests were done. Results One-third of the 4198 cases with febrile episodes of three or more days detected in the community were screened at the centers; 341 were clinically suspected of having Typhoid Fever. Forty-nine were positive by culture whereas 161 were positive by serology. Ten cases were multi-drug resistant. Incidence of culture-proven Typhoid was estimated to be 170 (95% CI: 120, 220)/100000 population, whereas serology-based incidence was 710 (95% CI: 620, 810)/100000 population. Peak incidence was noted in October followed by May and June. Conclusion Passive surveillance, even when augmented by household visits, misses a significant portion of suspected cases. Morbidity of Typhoid is quite high in Pakistan and needs public health intervention. Hot months have higher incidence of Typhoid. Healthcare behavior studies will help to develop a better surveillance system.
Leonard Leibovici - One of the best experts on this subject based on the ideXlab platform.
-
vaccines for preventing Typhoid Fever
Cochrane Database of Systematic Reviews, 2014Co-Authors: Elspeth Anwar, Camilo J Acosta, Abigail Fraser, Mical Paul, Elad Goldberg, Leonard LeiboviciAbstract:Background Typhoid Fever and paraTyphoid Fever continue to be important causes of illness and death, particularly among children and adolescents in south-central and southeast Asia. Two Typhoid vaccines are commercially available, Ty21a (oral) and Vi polysaccharide (parenteral), but neither is used routinely. Other vaccines, such as a new, modified, conjugated Vi vaccine called Vi-rEPA, are in development. Objectives To evaluate the efficacy and adverse effects of vaccines used to prevent Typhoid Fever. Search methods In June 2013, we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL, MEDLINE, EMBASE, LILACS, and mRCT. We also searched relevant conference proceedings up to 2013 and scanned the reference lists of all included trials. Selection criteria Randomized and quasi-randomized controlled trials (RCTs) comparing Typhoid Fever vaccines with other Typhoid Fever vaccines or with an inactive agent (placebo or vaccine for a different disease). Data collection and analysis Two review authors independently applied inclusion criteria and extracted data. We computed vaccine efficacy per year of follow-up and cumulative three-year efficacy, stratifying for vaccine type and dose. The outcome addressed was Typhoid Fever, defined as isolation of Salmonella typhi in blood. We calculated risk ratios (RRs) and efficacy (1-RR as a percentage) with 95% confidence intervals (CIs). Main results In total, 18 RCTs were included in this review; 12 evaluated efficacy (Ty21a: five trials; Vi polysaccharide: six trials; Vi-rEPA: one trial), and 11 reported on adverse events. Ty21a vaccine (oral vaccine, three doses) A three-dose schedule of Ty21a vaccine prevents around one-third to one-half of Typhoid cases in the first two years after vaccination (Year 1: 35%, 95% CI 8% to 54%; Year 2: 58%, 95% CI 40% to 71%; one trial, 20,543 participants; moderate quality evidence; data taken from a single trial conducted in Indonesia in the 1980s). No benefit was detected in the third year after vaccination. Four additional cluster-RCTs have been conducted, but the study authors did not adjust for clustering. Compared with placebo, this vaccine was not associated with more participants with vomiting, diarrhoea, nausea or abdominal pain (four trials, 2066 participants; moderate quality evidence) headache, or rash (two trials, 1190 participants; moderate quality evidence); however, Fever (four trials, 2066 participants; moderate quality evidence) was more common in the vaccine group. Vi polysaccharide vaccine (injection, one dose) A single dose of Vi polysaccharide vaccine prevents around two-thirds of Typhoid cases in the first year after vaccination (Year 1: 69%, 95% CI 63% to 74%; three trials, 99,979 participants; high quality evidence). In Year 2, the trial results were more variable, with the vaccine preventing between 45% and 69% of Typhoid cases (Year 2: 59%, 95% CI 45% to 69%; four trials, 194,969 participants; moderate quality evidence). The three-year cumulative efficacy of the vaccine is around 55% (95% CI 30% to 70%; 11,384 participants, one trial; moderate quality evidence). These data are taken from a single trial in South Africa in the 1980s. Compared with placebo, this vaccine was not associated with more participants with Fever (four trials, 133,038 participants; moderate quality evidence) or erythema (three trials, 132,261 participants; low quality evidence); however, swelling (three trials, 1767 participants; moderate quality evidence) and pain at the injection site (one trial, 667 participants; moderate quality evidence) were more common in the vaccine group. Vi-rEPA vaccine (two doses) Administration of two doses of the Vi-rEPA vaccine prevents between 50% and 96% of Typhoid cases during the first two years after vaccination (Year 1: 94%, 95% CI 75% to 99%; Year 2: 87%, 95% CI 56% to 96%; one trial, 12,008 participants; moderate quality evidence). These data are taken from a single trial with children 2 to 5 years of age conducted in Vietnam. Compared with placebo, the first and second doses of this vaccine were not associated with increased risk of adverse events. The first dose of this vaccine was not associated with Fever (2 studies, 12,209 participants; low quality evidence), erythema (two trials, 12,209 participants; moderate quality evidence) or swelling at the injection site (two trials, 12,209 participants; moderate quality evidence). The second dose of this vaccine was not associated with Fever (two trials, 11,286 participants; low quality evidence), erythema (two trials, 11,286 participants; moderate quality evidence) and swelling at the injection site (two trials, 11,286 participants; moderate quality evidence). Authors' conclusions The licensed Ty21a and Vi polysaccharide vaccines are efficacious. The new and unlicensed Vi-rEPA vaccine is as efficacious and may confer longer immunity.
-
Typhoid Fever vaccines systematic review and meta analysis of randomised controlled trials
Vaccine, 2007Co-Authors: Abigail Fraser, Camilo J Acosta, Mical Paul, Elad Goldberg, Leonard LeiboviciAbstract:We undertook a systematic review and meta-analysis of randomised controlled trials comparing a Typhoid Fever vaccine with any alternative Typhoid Fever vaccine or inactive agent. Trials evaluating killed whole-cell vaccines were excluded. The cumulative efficacy at 3 years for the Ty21a and the polysaccharide Vi vaccine were similar: 51% (95%CI 36%, 62%), and 55% (95%CI 30%, 70%), respectively. The cumulative efficacy of the Vi-rEPA vaccine at 3.8 years was higher, 89% (95%CI 76%, 97%), but this vaccine has not yet been licensed for use and was evaluated in only one trial. Adverse events were mild in nature and for most, not significantly more frequent in any of the vaccine groups when compared with placebo. Both the currently licensed Ty21a and Vi vaccine, are safe and efficacious for preventing Typhoid Fever. Neither vaccine is currently registered for administration to children below 2 years of age. Given the recent finding that Typhoid Fever also affects infants, development of a conjugate vaccine is warranted.
