Incidence Of Typhoid Fever Research Articles

Evaluation of naturally occurring IgG anti-Vi antibody titers as predictors and correlates of typhoid fever in Dhaka, Bangladesh.

When delivered through vaccination Vi-polysaccharide antigen of Salmonella enterica serotype Typhi protects against typhoid by inducing IgG anti-Vi antibodies. We aimed to determine whether the presence of antibodies following natural infection is associated with a lower incidence of typhoid fever in endemic regions. We analyzed data from a cohort study of typhoid fever conducted in Dhaka, Bangladesh. Plasma IgG anti-Vi antibodies were measured using a standard enzyme-linked immunosorbent assay in random serosurveys of a population that had not previously received typhoid vaccination. Participants were followed for up to 20 months for culture-confirmed typhoid fever. The receiver operating characteristic (ROC) curve and Cox proportional hazard models were used to evaluate the associations between antibody levels and typhoid risk. The ROC analysis revealed that IgG anti-Vi antibody titers were predictive of typhoid risk among the 8,261 serosurvey participants (area under the curve: 0·63; 95% confidence interval (CI): 0·58─0·67). Detection of any antibodies was associated with a lower risk of typhoid in crude analyses (hazard ratio (HR): 0·13; 95% CI: 0·03─0·52), though this association declined after adjustment (HR: 0·32; 95% CI: 0·07─1·40). A positive correlation was observed between IgG anti-Vi titers and age (correlation coefficient 0·35; p < 0·001), with a stepwise increase in detectable antibodies by age, ranging from 12·0% (280/2,333) in children under 5 years to 54·2% (463/854) in individuals 50 years and older (p < 0·001). In typhoid-endemic populations, IgG anti-Vi antibodies may indicate natural immunity to typhoid. The increasing seroprevalence with age suggests that these antibodies could serve as markers of cumulative past typhoid infections. Future research should explore these possibilities. Not applicable.

Time series data on typhoid fever incidence during outbreaks from 2000 to 2022

This article presents a comprehensive dataset compiling reported cases of typhoid fever from culture-confirmed outbreaks across various geographical locations from 2000 through 2022, categorized into daily, weekly, and monthly time series. The dataset was curated by identifying peer-reviewed epidemiological studies available in PubMed, OVID-Medline, and OVID-Embase. Time-series incidence data were extracted from plots using WebPlotDigitizer, followed by verification of a subset of the dataset. The primary aim of this dataset is to serve as a foundational tool for researchers and policymakers, enabling the development of robust, model-based strategies for the control of typhoid fever outbreaks. The article describes the method by which the dataset has been compiled and how the quality of the data has been verified. Furthermore, it discusses the dataset’s potential applications in optimizing vaccination campaigns, improving public health planning, and tailoring interventions to specific epidemiologic contexts. This article contributes significantly to the field of infectious disease modeling, offering a valuable resource for enhancing typhoid fever control measures globally.

Evaluating the Antibacterial Potential of Commercial Herbal Mixtures against Clinical Isolate of Salmonella typhi: An In-vitro Experimental Analysis

Background: Typhoid fever incidence has continuously increased, particularly in developing countries. As a result, there has been an influx of preference for herbal remedies to meet the growing demand. However, the increasing demand for these herbal preparations has created room for false claims. Aim: This study investigated the in vitro activity of commercial herbal mixtures against a clinical isolate of S. typhi. Study Design: The study employed an experimental design to evaluate the vitro activity of four commercial herbal mixtures against a clinical isolate of S. typhi. Methods: Four herbal mixtures (IBA-ENTR5, DB-TYFO222, DY-PHB, and BIA-TABH) were screened for phytochemical and antimicrobial activity. Screening and identification of bioactive secondary metabolites were performed using standard procedures. The antimicrobial activity and minimum inhibitory concentration (MIC) were determined using the agar well diffusion and dilution method. Results: Based on photochemical screening, apart from the absence of glycosides in IBA-ENTR5, all other phytochemicals were present in the herbal mixtures. The highest activity per agar well diffusion was observed for IBA-ENTR5, followed by DB-TYFO222, DY-PHB, and BIA-TABH. The minimum inhibitory concentration values ranged from 150 to 250 mg/L, with IBA-ENTR5 and DY-PHB possessing 150 mg/L, DB-TYFO222 possessing 200 mg/L, and BIA-TABH possessing 250 mg/L. Compared with the positive control IAG-CPRO, only IBA-ENTR exhibited a higher inhibition zone. Conclusion: This study revealed that herbal mixtures contain rich phytochemical constituents. The results also confirmed that the antimicrobial activity and minimum inhibitory concentration of the herbal mixtures were concentration-dependent. That is, the herbal mixtures sampled provided good results when their concentrations were increased. In conclusion, herbal mixtures in open Ghanaian markets may provide good antimicrobial efficacy.

Global burden, trends and inequalities for typhoid and paratyphoid fever among children younger than 15years over the past 30years.

Typhoid and paratyphoid fever, collectively known as enteric fever, are systemic infections caused by Salmonella enterica and are highly prevalent in children. We aimed to describe the global burden, trends and inequalities of enteric fever among children under 15years from 1990 to 2019 based on data from the Global Burden of Diseases, Injuries, and Risk Factors Study 2019 (GBD 2019). In this secondary analysis of GBD 2019, we extracted data for incident cases, deaths and disability-adjusted life-years (DALYs) as measures of enteric fever burden. We estimated the average annual percentage changes (AAPCs) in enteric fever incidence, mortality and DALYs rate to quantify trends over time. Cross-country inequalities in enteric fever incidence were measured using the slope index of inequality and concentration index. In 2019, the global cases of typhoid and paratyphoid were 4 833 282 and 1 793 172, respectively, both lower than those in 1990. On secondary analysis, paratyphoid incidence decreased at a faster rate than typhoid from 1990 to 2009, whereas the incidence of paratyphoid (AAPC = -3.78, 95% CI: -4.07, -3.49) declined slower than that of typhoid (AAPC = -4.32, 95% CI: -4.50, -4.13) from 2010 to 2019 (P < 0.05) at the global level. The incidence burden of enteric fever increased in Australasia (AAPC = 1.28, 95% CI: 0.77, 1.78) and Western Europe (AAPC = 0.77, 95% CI: 0.44, 1.11). Death and DALYs burden in low socio-demographic index (SDI) region showed a stable trend. A significant reduction in SDI-related inequality occurred, with the concentration index falling from -0.31 in 1990 to -0.22 in 2019. The global disease burden of enteric fever and the magnitude of inequalities across countries have declined since 1990, but low SDI countries remain a region of concern. Travellers from Oceania and Western Europe to endemic regions should be particularly aware of the risk of enteric fever.

Review Article on Typhoid Fever

Typhoid fever is primarily found in impoverished countries with inadequate sanitation on a global scale. In the United States, the incidence of typhoid fever has been steadily decreasing since 1900 due to improvements in sanitation and effective antibiotic treatments. While typhoid fever is widespread, 80% of cases occur in the Americas, the Caribbean, Oceania, Bangladesh, China, India, Indonesia, Laos, and Nepal. Each year, approximately 200,000 individuals succumb to typhoid fever, and 21.6 million people are infected with the disease. When treated, the chance of death is 0.2% and there are rarely long-term symptoms. Untreated typhoid fever can lead to fatality and persist for multiple weeks. Lasting complications may involve central nervous system damage. 54 percent of reported typhoid fever cases in the United States between 1999 and 2006 included. One can receive fluids and electrolytes via a vein. For the treatment of typhoid fever, the patient can receive an antibiotic and, in rare circumstances, steroid medications. When prescribed antibiotics, most patients start feeling better after two days, and fatalities are rare. Typhoid cases are generally treated with specific antibiotics such ciprofloxacin, ampicillin, or chloramphenicol. Important public health measures include proper water purification, proper waste disposal, and safeguarding the food supply from contamination. Typhoid carriers should not be permitted to handle food in any capacity. If treatment is not received, patients may have a fever for weeks or months, and up to 20% of them may pass away from infection-related problems. The hospital setting is where those with infections are treated.

5-year vaccine protection following a single dose of Vi-tetanus toxoid conjugate vaccine in Bangladeshi children (TyVOID): a cluster randomised trial

WHO currently recommends a single dose of typhoid conjugate vaccine (TCV) in high-burden countries based on 2-year vaccine efficacy data from large randomised controlled trials. Given the decay of immunogenicity, the protection beyond 2 years is unknown. We therefore extended the follow-up of the TyVAC trial in Bangladesh to assess waning of vaccine protection to 5 years after vaccination. We conducted a cluster randomised controlled trial (TyVAC; ISRCTN11643110) in Dhaka, Bangladesh, between 2018 and 2021. Children aged 9 months to 15 years were invited to receive a single dose of TCV or Japanese encephalitis vaccine between April 15, 2018, and November 16, 2019, based on the randomisation of their clusters of residence. Children who received the Japanese encephalitis vaccine were invited to receive TCV at the final visit between Jan 6, and Aug 31, 2021, according to the protocol. This follow-on study extended the follow-up of the original trial until Aug 14, 2023. The primary endpoint of this study was to compare the incidence of blood culture-confirmed typhoid between children who received TCV in 2018-19 (the previous-TCV group) and those who received the vaccine in 2021 (the recent-TCV group), to evaluate the relative decline in vaccine protection. We also did a nested study using the test-negative design comparing the recent-TCV and previous-TCV groups with unvaccinated individuals, as well as an immunogenicity study in a subset of 1500 children. Compared with the recent-TCV group, the previous-TCV group had an increased risk of typhoid fever between 2021-23, with an adjusted incidence rate ratio of 3·10 (95% CI 1·53 to 6·29; p<0·0001), indicating a decline in the protection of a single-dose of TCV 3-5 years after vaccination. The extrapolated vaccine effectiveness in years 3-5 was 50% (95% CI -13 to 78), and was validated using the test-negative design analysis, with a vaccine effectiveness of 84% (74 to 90) in the recent-TCV group and 55% (36 to 68) in the previous-TCV group, compared with unvaccinated individuals. Anti-Vi-IgG responses declined over the study period. The highest rate of decay was seen in children vaccinated at younger than 2 years in the original trial. The inverse correlation between age and the decay of antibodies was also seen in the subgroup analysis of vaccine effectiveness, where the youngest age group (<7 years at fever visits) exhibited the fastest waning, with vaccine effectiveness dropping to 24% (95% CI -29 to 55) at 3-5 years after vaccination. A decline in the protection conferred by a single-dose TCV was observed 3-5 years after vaccination, with the greatest decline in protection and immune responses observed in children vaccinated at younger ages. A booster dose of TCV around school entry age might be needed for children vaccinated while younger than 2 years to sustain protection against typhoid fever during the school years when the risk is the highest. The Bill & Melinda Gates Foundation.

Incidence of Typhoid Fever Infection among Febrile Patients attending FUDMA Clinic

Typhoid fever remains a public health concern in Nigeria, with its incidence poising substantial challenges to health care systems. Widal agglutination test is largely the only used diagnostic test method for the laboratory diagnosis of Typhoid infection which has been proven to be neither sensitive nor specific. This paper delves into the incidence, contributory factors as well as sensitivity and specificity of commonly used diagnostic tests of typhoid fever infection among febrile patients attending the FUDMA Clinic. A total of 55 Blood and stool samples were analyzed using standard procedures for slide agglutination test (Widal) and stool culture, before culturing, the samples were first inoculated in an enrichment medium (Selenite-F broth). After 4 hours of pre-enrichment, the samples were inoculated into Salmonella Shigella Agar and Mackonkey agar, while catalase, TSI, citrate utilization test, Indole test, and urease tests served to identify the organism biochemically. Socio-demographic data revealed that 55 Participants, 52.8% were males, 72.7% were students and 80% were singles. Slide agglutination test recorded a 90.9% incidence rate, stool culture had an incidence rate of 18.18%. Among the age groups that enrolled in this study, a 44.1% incidence rate was recorded among the age Group 20-26 years. Stool culture was to found have performed better diagnostically with a sensitivity of 60% as well as a specificity of 40%. Conclusively, A high Incidence of typhoid fever was observed in this study. This Therefore suggests that there is an urgent need for improved personal hygiene and more accessibility to potable drinking water.

Environmental surveillance for Salmonella Typhi in rivers and wastewater from an informal sewage network in Blantyre, Malawi.

Environmental surveillance for Salmonella Typhi may provide information on the community-level dynamics of typhoid fever in resource poor regions experiencing high disease burden. Many knowledge gaps concerning the feasibility of ES remain, especially in areas lacking formal sewage systems. We implemented protocols for S. Typhi ES, including site selection and catchment population estimation, sample concentration and testing using qPCR for S. Typhi specific gene targets. Between May 2021 and May 2022, we collected grab samples and Moore swabs from 43 sites in Blantyre, Malawi. Catchment characteristics, water quality, and human faecal contamination (qPCR for Bacteroides HF183) were also recorded. Their association with S. Typhi detection was investigated using a logistic mixed-effects regression analysis. Prevalence of S. Typhi in ES samples was 2.1% (1.1-4.0%) and 3.9% (1.9-7.9%) for grab and Moore swab samples, respectively. HF183 was associated S. Typhi positivity, with a unit increase in log genome copies/microlitre increasing the odds of detection of S. Typhi by 1.56 (95% CI: 1.29-1.89) and 1.33 (1.10-1.61) in Moore swabs and grab samples, respectively. The location and timing of S. Typhi detection through ES was not associated with the incidence of typhoid fever reported in associated catchment populations. During this period of relatively low typhoid fever incidence, wastewater surveillance continued to detect S. Typhi in human sewage and wastewater suggesting that ES using natural river systems can be a sensitive indicator of transmission.

Modelling Salmonella Typhi in high-density urban Blantyre neighbourhood, Malawi, using point pattern methods

Salmonella Typhi is a human-restricted pathogen that is transmitted by the faecal–oral route and causative organism of typhoid fever. Using health facility data from 2016 to 2020, this study focuses on modelling the spatial variation in typhoid risk in Ndirande township in Blantyre. To pursue this objective, we developed a marked inhomogeneous Poisson process model that allows us to incorporate both individual-level and environmental risk factors. The results from our analysis indicate that typhoid cases are spatially clustered, with the incidence decreasing by 54% for a unit increase in the water, sanitation, and hygiene (WASH) score. Typhoid intensity was also higher in children aged below 18 years than in adults. However, our results did not show evidence of a strong temporal variation in typhoid incidence. We also discuss the inferential benefits of using point pattern models to characterise the spatial variation in typhoid risk and outline possible extensions of the proposed modelling framework.

Supporting health systems and environment in the Democratic Republic of Congo: A call for action.

Developing nations have to overcome a number of obstacles to fulfill the Sustainable Development Goals. The Democratic Republic of Congo is one of the five poorest nations in the world and faces several challenges in combating problems related to poverty, health, and sanitation while linking the environment to anthropogenic activities. This study analyzes anthropogenic activities and their impact on the environment while providing access to the public health of the Congolese population based on the objectives of sustainable development. Thirty-five articles were selected for further analysis as well as relative data. In 2022, 21 million cases of malaria were recorded by the national malaria control program, with 13,000 cases of death. The Democratic Republic of Congo has the highest typhoid incidence, with 315 cases per 100,000 people. A number of 31,342 cases of cholera were reported in 2023, according to multiple reports, with 230 deaths, mainly affecting children. In the same year, a triple epidemic of typhoid, shigellosis, and cholera was identified, with 2389 cases and 52 deaths. These observations cause a health emergency, which can be alleviated and resolved by the establishment of an adequate sanitation system. Waste can be recycled and returned to usable raw materials. Finally, it will be necessary to establish a water safety management plan to combat all diseases linked to the consumption of nonpotable water and improve national coverage on the treatment of recent cases to reduce and at best avoid observed cases of death.

The Relationship of Hand Washing Behavior with Soap and the Incidence of Typhoid Fever in Children Aged 5 - 12 Years in RW 01 Cikembar Village Cikembar District Sukabumi Dist

The general aim of this research is to determine the relationship between hand washing behavior with soap and the incidence of typhoid fever in children aged 5-12 years. This research is a quantitative research with a cross sectional approach. The research population was children aged 5-12 years in rw 01, Cikembar village, Cikembar sub-district, Sukabumi district, from August to September 2023, data were obtained for 98 people. The research sample was 98 children aged 5-12 years who were determined using total sampling techniques. Research data was collected using a questionnaire which was then analyzed using chi square analysis. The results of the study showed that the chi square test results of the relationship between hand washing behavior with soap and the incidence of typhoid fever obtained a value (p-Value = 0.000) so that H0 was rejected and the chi square test results of the relationship between snack consumption and the incidence of typhoid obtained a value (p-Value = 0.377) so that H0 is rejected. It is proven that the habit of washing hands before eating influences the incidence of typhoid fever.

Cost-effectiveness and public health impact of typhoid conjugate vaccine introduction strategies in Bangladesh

PurposeTyphoid fever causes substantial morbidity and mortality in Bangladesh. The government of Bangladesh plans to introduce typhoid conjugate vaccines (TCV) in its expanded program on immunization (EPI) schedule. However, the optimal introduction strategy in addition to the costs and benefits of such a program are unclear. MethodsWe extended an existing mathematical model of typhoid transmission to integrate cost data, clinical incidence data, and recently conducted serosurveys in urban, semi-urban, and rural areas. In our primary analysis, we evaluated the status quo (i.e., no vaccination) and eight vaccine introduction strategies including routine and 1-time campaign strategies, which differed by age groups targeted and geographic focus. Model outcomes included clinical incidence, seroincidence, deaths, costs, disability-adjusted life years (DALYs), and incremental cost-effectiveness ratios (ICERs) for each strategy. We adopted a societal perspective, 10-year model time horizon, and 3 % annual discount rate. We performed probabilistic, one-way, and scenario sensitivity analyses including adopting a healthcare perspective and alternate model time horizons. ResultsWe projected that all TCV strategies would be cost saving compared to the status quo. The preferred strategy was a nationwide introduction of TCV at 9–12 months of age with a single catch-up campaign for children ages 1–15, which was cost saving compared to all other strategies and the status quo. In the 10 years following implementation, we projected this strategy would avert 3.77 million cases (95 % CrI: 2.60 – 5.18), 11.31 thousand deaths (95 % CrI: 3.77 – 23.60), and save $172.35 million (95 % CrI: −14.29 – 460.59) compared to the status quo. Our findings were broadly robust to changes in parameter values and willingness-to-pay thresholds. ConclusionsWe projected that nationwide TCV introduction with a catch-up campaign would substantially reduce typhoid incidence and very likely be cost saving in Bangladesh.

Incidence of typhoid fever in Burkina Faso, Democratic Republic of the Congo, Ethiopia, Ghana, Madagascar, and Nigeria (the Severe Typhoid in Africa programme): a population-based study

Typhoid Fever remains a major cause of morbidity and mortality in low-income settings. The Severe Typhoid in Africa programme was designed to address regional gaps in typhoid burden data and identify populations eligible for interventions using novel typhoid conjugate vaccines. A hybrid design, hospital-based prospective surveillance with population-based health-care utilisation surveys, was implemented in six countries in sub-Saharan Africa. Patients presenting with fever (≥37·5°C axillary or ≥38·0°C tympanic) or reporting fever for three consecutive days within the previous 7 days were invited to participate. Typhoid fever was ascertained by culture of blood collected upon enrolment. Disease incidence at the population level was estimated using a Bayesian mixture model. 27 866 (33·8%) of 82 491 participants who met inclusion criteria were recruited. Blood cultures were performed for 27 544 (98·8%) of enrolled participants. Clinically significant organisms were detected in 2136 (7·7%) of these cultures, and 346 (16·2%) Salmonella enterica serovar Typhi were isolated. The overall adjusted incidence per 100 000 person-years of observation was highest in Kavuaya and Nkandu 1, Democratic Republic of the Congo (315, 95% credible interval 254-390). Overall, 46 (16·4%) of 280 tested isolates showed ciprofloxacin non-susceptibility. High disease incidence (ie, >100 per 100 000 person-years of observation) recorded in four countries, the prevalence of typhoid hospitalisations and complicated disease, and the threat of resistant typhoid strains strengthen the need for rapid dispatch and implementation of effective typhoid conjugate vaccines along with measures designed to improve clean water, sanitation, and hygiene practices. The Bill & Melinda Gates Foundation.

Estimating the subnational prevalence of antimicrobial resistant Salmonella enterica serovars Typhi and Paratyphi A infections in 75 endemic countries, 1990-2019: a modelling study.

Enteric fever, a systemic infection caused by Salmonella enterica serovars Typhi and Paratyphi A, remains a major cause of morbidity and mortality in low-income and middle-income countries. Enteric fever is preventable through the provision of clean water and adequate sanitation and can be successfully treated with antibiotics. However, high levels of antimicrobial resistance (AMR) compromise the effectiveness of treatment. We provide estimates of the prevalence of AMR S Typhi and S Paratyphi A in 75 endemic countries, including 30 locations without data. We used a Bayesian spatiotemporal modelling framework to estimate the percentage of multidrug resistance (MDR), fluoroquinolone non-susceptibility (FQNS), and third-generation cephalosporin resistance in S Typhi and S Paratyphi A infections for 1403 administrative level one districts in 75 endemic countries from 1990 to 2019. We incorporated data from a comprehensive systematic review, public health surveillance networks, and large multicountry studies on enteric fever. Estimates of the prevalence of AMR and the number of AMR infections (based on enteric fever incidence estimates by the Global Burden of Diseases study) were produced at the country, super-region, and total endemic area level for each year of the study. We collated data from 601 sources, comprising 184 225 isolates of S Typhi and S Paratyphi A, covering 45 countries over 30 years. We identified a decline of MDR S Typhi in south Asia and southeast Asia, whereas in sub-Saharan Africa, the overall prevalence increased from 6·0% (95% uncertainty interval 4·3-8·0) in 1990 to 72·7% (67·7-77·3) in 2019. Starting from low levels in 1990, the prevalence of FQNS S Typhi increased rapidly, reaching 95·2% (91·4-97·7) in south Asia in 2019. This corresponded to 2·5 million (1·5-3·8) MDR S Typhi infections and 7·4 million (4·7-11·3) FQNS S Typhi infections in endemic countries in 2019. The prevalence of third-generation cephalosporin-resistant S Typhi remained low across the whole endemic area over the study period, except for Pakistan where prevalence of third-generation cephalosporin resistance in S Typhi reached 61·0% (58·0-63·8) in 2019. For S Paratyphi A, we estimated low prevalence of MDR and third-generation cephalosporin resistance in all endemic countries, but a drastic increase of FQNS, which reached 95·0% (93·7-96·1; 3·5 million [2·2-5·6] infections) in 2019. This study provides a comprehensive and detailed analysis of the prevalence of MDR, FQNS, and third-generation cephalosporin resistance in S Typhi and S Paratyphi A infections in endemic countries, spanning the last 30 years. Our analysis highlights the increasing levels of AMR in this preventable infection and serves as a resource to guide urgently needed public health interventions, such as improvements in water, sanitation, and hygiene and typhoid fever vaccination campaigns. Fleming Fund, UK Department of Health and Social Care; Wellcome Trust; and Bill and Melinda Gates Foundation.

Mapping the incidence rate of typhoid fever in sub-Saharan Africa.

With more than 1.2 million illnesses and 29,000 deaths in sub-Saharan Africa in 2017, typhoid fever continues to be a major public health problem. Effective control of the disease would benefit from an understanding of the subnational geospatial distribution of the disease incidence. We collated records of the incidence rate of typhoid fever confirmed by culture of blood in Africa from 2000 to 2022. We estimated the typhoid incidence rate for sub-Saharan Africa on 20 km × 20 km grids by exploring the association with geospatial covariates representing access to improved water and sanitation, health conditions of the population, and environmental conditions. We identified six published articles and one pre-print representing incidence rate estimates in 22 sites in 2000-2022. Estimated incidence rates showed geospatial variation at sub-national, national, and regional levels. The incidence rate was high in Western and Eastern African subregions followed by Southern and Middle African subregions. By age, the incidence rate was highest among 5-14 yo followed by 2-4 yo, > 14 yo, and 0-1 yo. When aggregated across all age classes and grids that comprise each country, predicted incidence rates ranged from 43.7 (95% confidence interval: 0.6 to 591.2) in Zimbabwe to 2,957.8 (95% CI: 20.8 to 4,245.2) in South Sudan per 100,000 person-years. Sub-national heterogeneity was evident with the coefficient of variation at the 20 km × 20 km grid-level ranging from 0.7 to 3.3 and was generally lower in high-incidence countries and widely varying in low-incidence countries. Our study provides estimates of 20 km × 20 km incidence rate of typhoid fever across sub-Saharan Africa based on data collected from 2000 through 2020. Increased understanding of the subnational geospatial variation of typhoid fever in Africa may inform more effective intervention programs by better targeting resources to heterogeneously disturbed disease risk.

Epidemiological characteristics of typhoid fever in Fujian Province, 2011-2022

Objective: To analyze the incidence trend and epidemiological characteristics of typhoid fever in Fujian Province from 2011 to 2022, and understand the high-incidence population and hotspot areas, and provide evidences to develop more targeted prevention and control measures. Methods: The surveillance data of typhoid fever during 2011-2022 in Fujian Province were obtained from the National Disease Reporting Information System and analyzed with SAS 9.4. The spatial autocorrelation analysis of typhoid fever incidence at county/district levels was performed with ArcGlS 10.8. Results: A total of 5 126 cases of typhoid fever were reported in Fujian Province from 2011 to 2022, with an average annual incidence rate of 1.10/100 000. The average annual incidence rate was 0.96/100 000 from 2011 to 2015, 1.49/100 000 from 2016 to 2019, and 0.81/100 000 from 2020 to 2022. The disease occurred all the year round, with high epidemic season from May to September. A total of 23.59% (1 209/5 126) of the cases occurred at the age of 0-4, and 9.62% (493/5 126) at the age of 5-9. The male to female ratio of the cases was 0.97∶1 (2 524∶2 602) for the whole population, 1.19∶1 (925∶777) for people under 10 years old, 0.75∶1 (1 060∶1 404) for people between 10 and 54 years old, and 1.28∶1 (539∶421) for people over 55 years old. Cases in Ningde City accounted for 30.65% (1 571/5 126) of the total cases. Most hotspots were occurred in Ningde City. Recurrent and clustered cases were found in family members. Conclusions: Typhoid fever was prevalent at a low level in Fujian Province during 2011-2022, indicating that strengthening the prevention and control measures should target key areas and populations. The incidence of typhoid fever in Fujian Province showed spatial aggregation phenomenon, and most cases gathered in Ningde City. Intensive study for the influencing factors of spatial clustering should be conducted.

Detection of Salmonella Typhi bacteriophages in surface waters as a scalable approach to environmental surveillance.

Environmental surveillance, using detection of Salmonella Typhi DNA, has emerged as a potentially useful tool to identify typhoid-endemic settings; however, it is relatively costly and requires molecular diagnostic capacity. We sought to determine whether S. Typhi bacteriophages are abundant in water sources in a typhoid-endemic setting, using low-cost assays. We collected drinking and surface water samples from urban, peri-urban and rural areas in 4 regions of Nepal. We performed a double agar overlay with S. Typhi to assess the presence of bacteriophages. We isolated and tested phages against multiple strains to assess their host range. We performed whole genome sequencing of isolated phages, and generated phylogenies using conserved genes. S. Typhi-specific bacteriophages were detected in 54.9% (198/361) of river and 6.3% (1/16) drinking water samples from the Kathmandu Valley and Kavrepalanchok. Water samples collected within or downstream of population-dense areas were more likely to be positive (72.6%, 193/266) than those collected upstream from population centers (5.3%, 5/95) (p=0.005). In urban Biratnagar and rural Dolakha, where typhoid incidence is low, only 6.7% (1/15, Biratnagar) and 0% (0/16, Dolakha) river water samples contained phages. All S. Typhi phages were unable to infect other Salmonella and non-Salmonella strains, nor a Vi-knockout S. Typhi strain. Representative strains from S. Typhi lineages were variably susceptible to the isolated phages. Phylogenetic analysis showed that S. Typhi phages belonged to the class Caudoviricetes and clustered in three distinct groups. S. Typhi bacteriophages were highly abundant in surface waters of typhoid-endemic communities but rarely detected in low typhoid burden communities. Bacteriophages recovered were specific for S. Typhi and required Vi polysaccharide for infection. Screening small volumes of water with simple, low-cost (~$2) plaque assays enables detection of S. Typhi phages and should be further evaluated as a scalable tool for typhoid environmental surveillance.

A phase II clinical trial of a Vi-DT typhoid conjugate vaccine in healthy Indonesian adolescents and adults: one-month evaluation of safety and immunogenicity

BackgroundTyphoid fever is commonly found until today, especially in developing countries. It has fatal complications and measures must be taken to reduce the incidence of typhoid. Vaccinations are a key factor in prevention. This is a phase II randomized observer-blind clinical trial on a novel Vi-DT conjugate vaccine on 200 subjects 12 to 40 years of age.MethodsSubjects were screened for eligibility after which a blood sample was taken and one dose of vaccine was administered. Investigational vaccine used was Vi-DT and control was Vi-PS. Twenty-eight days after vaccination, subjects visited for providing blood sample to assess immunogenicity and were asked about local and systemic adverse reactions that occurred in the first 28 days.ResultsSubjects had minor adverse reactions. Pain was the most common local reaction. Muscle pain was the most common systemic reaction. There were no serious adverse events up to 28 days post vaccination. Seroconversion rates were 100% in the Vi-DT group and 95.96% in the Vi-PS group. Post vaccination GMTs were increased in both groups but it was significantly higher in the Vi-DT group (p < 0.001).ConclusionsVi-DT typhoid conjugate vaccine is safe and immunogenic in healthy Indonesian subjects 12 to 40 years.Trial registrationApproved by ClinicalTrials.gov. Clinical trial registration number: NCT03460405. Registered on 09/03/2018. URL: https://clinicaltrials.gov/ct2/show/NCT03460405.

Trends and Spatial Pattern Analysis of Typhoid and Paratyphoid Fever Incidence - Yunnan Province, China, 1989-2022.

This study explored the incidence trends and spatial clustering of typhoid and paratyphoid fever (TPF) in Yunnan Province to provide scientific evidence for developing and improving prevention and control strategies. Temporal trends were investigated by calculating the annual percent change (APC) and average annual percent change (AAPC), along with their 95% confidence intervals (CIs). The spatial clustering of TPF across Yunnan Province was examined using global Moran's I and local indicators of spatial association (LISA) statistics. A total of 206,066 TPF cases were reported in Yunnan Province from 1989 to 2022, with an average annual incidence of 13.98 per 100,000 population and a case fatality rate of 2.5 per 1,000. The greatest number of cases was reported during July and August. The 25-34-year age group had the highest incidence, and farmers were prominently represented. TPF incidence in Yunnan Province showed a significant decrease and spatial clustering. From 2005 to 2022, 13 county-level cities/counties/municipal districts in 5 prefectures (cities) in Yunnan Province were identified as statistically significant H-H spatial clusters of TPF incidence. A total of 24 TPF outbreaks were reported in Yunnan Province from 2005 to 2022. The incidence of TPF in Yunnan Province showed a significant decrease and spatial clustering. Control strategies should focus on high-incidence areas, seasons, and populations to reduce the incidence of TPF.

Original Article Risk Factors for Enteric Fever in Children Aged 1 to 14 Years: A Cross-Sectional Study at Gandaki Province of Nepal

Introduction: Enteric fever is one of the major public health problems in Nepal. This study aimed to evaluate the risk factors associated with enteric fever in children Methods: This is prospective cross-sectional study conducted from April 15 to November 2023, with sample size of 139 children aged 1-14 years, diagnosed as enteric fever. Data were collected through pretested and validated proforma containing structured questionnaires. Data were analysed through SPSS version 23. Results: About seventy (69.8%) percent of the children had a history of consuming untreated water, and 52.5% lacked access to proper sanitation facilities. Additionally, 59% of the children were from low socioeconomic backgrounds, and 38.8% had close contact with infected individuals. The children from rural areas were more likely to be exposed to untreated water sources (73.9%) and had a higher prevalence of low socioeconomic status (62.5%) compared to their urban counterparts. Logistic regression analysis revealed that children exposed to untreated water were 2.1 times more likely to develop enteric fever than those not exposed, with this result being statistically significant (OR = 2.10, 95% CI = 1.30-3.40, p=0.002). Conclusion: Untreated water, inadequate sanitation, and low socioeconomic status as key risk factors for enteric fever in children. Rural children faced higher risks. Children exposed to untreated water were 2.1 times more likely to develop enteric fever than those not exposed, with this result being statistically significant. The findings underscore the need for improvement on water quality, sanitation, and socioeconomic conditions. Local health authorities should prioritize these areas to reduce enteric fever incidence, with further research recommended on intervention effectiveness.