Complications and mortality of typhoid fever: A global systematic review and meta-analysis

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

BACKGROUND

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 15 years from 1990 to 2019 based on data from the Global Burden of Diseases, Injuries, and Risk Factors Study 2019 (GBD 2019).

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Impact of Metabolites from Foodborne Pathogens on Cancer

Foodborne pathogens are microorganisms that cause illness through contamination, presenting significant risks to public health and food safety. This review explores the metabolites produced by these pathogens, including toxins and secondary metabolites, and their implications for human health, particularly concerning cancer risk. We examine various pathogens such as Salmonella sp., Campylobacter sp., Escherichia coli, and Listeria monocytogenes, detailing the specific metabolites of concern and their carcinogenic mechanisms. This study discusses analytical techniques for detecting these metabolites, such as chromatography, spectrometry, and immunoassays, along with the challenges associated with their detection. This study covers effective control strategies, including food processing techniques, sanitation practices, regulatory measures, and emerging technologies in pathogen control. This manuscript considers the broader public health implications of pathogen metabolites, highlighting the importance of robust health policies, public awareness, and education. This review identifies research gaps and innovative approaches, recommending advancements in detection methods, preventive strategies, and policy improvements to better manage the risks associated with foodborne pathogens and their metabolites.

Biochemical indices of patients with enteric fever and pancreatitis: A comparative cross-sectional study

Objective

Enteric fever (EF), a potentially fatal febrile illness, is prevalent in developing countries. Elevated levels of lipase and amylase in serum, typically associated with acute pancreatitis (AP), have been observed in patients with EF. The elevated enzymes in both conditions may lead to diagnostic confusion and care delays. This study aimed to determine biochemical indices that are peculiar to EF and AP.

Methods

A cross-sectional comparative study was conducted at the Korle-Bu Teaching Hospital, Ghana. Volunteers were categorized into three groups: EF (n = 32), AP (n = 30) and healthy controls (n = 31). A standard questionnaire was used to collect socio-demographic and clinical information from the participants. Blood and stool samples were obtained, followed by biochemical analysis: total amylase, lipase, pancreatic amylase, serum elastase 1, hepatic enzymes, calcium, magnesium, phosphate, stool colour, stool pH, and stool fat presence.

Results

The AP group displayed higher total amylase, lipase, elastase-1, alkaline phosphatase, aspartate aminotransferase, and gamma-glutamyl transferase levels compared to the EF and control groups (p < 0.05 respectively). Elastase 1 levels were found to be high in all AP participants, whereas no elevations were observed in the EF group. Positive associations were observed in the AP and EF groups for lipase vs total amylase (ρ = .543, p = 0.001; ρ = .543, p = 0.001 for both).

Conclusions

Elevated levels of total/pancreatic amylase and lipase were found to be indicative of a patient with AP and EF. Further, elastase-1 was found to be a good biomarker to distinguish between AP and EF.

Clinical and laboratory analysis of a large imported typhoid fever outbreak in The Netherlands

Typhoid fever is a rarely encountered disease in the Western world. In our study, patients with imported typhoid fever were characterized by a febrile illness with a relative bradycardia, headache and abdominal pain. Only a few patients presented with diarrhoea. An elevated CRP and lactate dehydrogenase (LD) were the most common laboratory abnormalities. Complications like focal abscesses occurred quite frequently.

Trends in antimicrobial resistance amongst Salmonella Typhi in Bangladesh: A 24-year retrospective observational study (1999-2022)

BACKGROUND

Rising antimicrobial resistance (AMR) in Salmonella Typhi restricts typhoid treatment options, heightening concerns for pan-oral drug-resistant outbreaks. However, lack of long-term temporal surveillance data on AMR in countries with high burden like Bangladesh is scarce. Our study explores the AMR trends of Salmonella Typhi isolates from Bangladesh, drawing comparisons with antibiotic consumption to optimize antibiotic stewardship strategies for the country.

METHODOLOGY/PRINCIPAL FINDINGS

The typhoid fever surveillance from 1999 to 2022 included two pediatric hospitals and three private clinics in Dhaka, Bangladesh. Blood cultures were performed at treating physicians' discretion; cases were confirmed by microbiological, serological, and biochemical tests. Antibiotic susceptibility was determined following CLSI guidelines. National antibiotic consumption data for cotrimoxazole, ciprofloxacin, and azithromycin was obtained from IQVIA-MIDAS database for comparison. Over the 24 years of surveillance, we recorded 12,435 culture-confirmed typhoid cases and observed declining resistance to first-line drugs (amoxicillin, chloramphenicol, and cotrimoxazole); multidrug resistance (MDR) decreased from 38% in 1999 to 17% in 2022. Cotrimoxazole consumption dropped from 0.8 to 0.1 Daily defined doses (DDD)/1000/day (1999-2020). Ciprofloxacin non-susceptibility persisted at >90% with unchanged consumption (1.1-1.3 DDD/1000/day, 2002-2020). Low ceftriaxone resistance (<1%) was observed, with slightly rising MIC (0.03 to 0.12 mg/L, 1999-2019). Azithromycin consumption increased (0.1 to 3.8 DDD/1000/day, 1999-2020), but resistance remained ≤4%.

CONCLUSION

Our study highlights declining MDR amongst Salmonella Typhi in Bangladesh; first-line antimicrobials could be reintroduced as empirical treatment options for typhoid fever if MDR rates further drops below 5%. The analysis also provides baseline data for monitoring the impact of future interventions like typhoid conjugate vaccines on typhoid burden and associated AMR.

Facile Synthesis of N-(4-Bromo-3-methylphenyl)pyrazine-2-carboxamide Derivatives, Their Antibacterial Activities against Clinically Isolated XDR S. Typhi, Alkaline Phosphatase Inhibitor Activities, and Docking Studies

The emergence of extensively drug-resistant Salmonella Typhi (XDR-S. Typhi) poses a grave public health threat due to its resistance to fluoroquinolones and third-generation cephalosporins. This resistance significantly complicates treatment options, underscoring the urgent need for new therapeutic strategies. In this study, we synthesized pyrazine carboxamides (3, 5a-5d) in good yields through the Suzuki reaction. Afterward, we evaluate their antibacterial activities against XDR-S. Typhi via the agar well diffusion method; 5d has the strongest antibacterial activity with MIC 6.25 (mg/mL). Moreover, in vitro Alkaline Phosphatase inhibitor activity was also determined; 5d is the most potent compound, with an IC50 of 1.469 ± 0.02 µM. Further, in silico studies were performed to find the type of interactions between synthesized compounds and target proteins.

Prevalence of typhoid fever and its associated factors among febrile patients visiting Arerti Primary Hospital, Amhara Region, north east Ethiopia

Background

Typhoid fever is one of the major public health concerns in developing countries, including Ethiopia. Understanding the burden and factors contributing to the transmission and development of the disease is crucial to applying appropriate preventive and therapeutic interventions.

Objective

To assess the prevalence of typhoid fever and its associated factors among febrile patients visiting Arerti Primary Hospital from 1 March to 30 May 2022.

Methods

A facility-based cross-sectional study was employed among 326 febrile patients visiting Arerti Primary Hospital for health services. The data were collected using laboratory procedures (widal test) and a structured interviewer-administered questionnaire. The data were entered using Epi Data version 3.1 and analyzed by SPSS version 25. Logistic regression was used to determine associations between variables. P-value < 0.05 and adjusted odds ratio with 95% confidence interval were used to measure the presence and strength of associations.

Results

In this study, of the total 317 cases that participated, the majority (64.4%) of them were males with age ranges from 13 to 63 years. The overall prevalence of positive antigen tests for typhoid infection was 30.0% (95% CI: 25.0%-35.3%). About 66.9% of the study participants had good knowledge, 75.7% had favorable perception, and 42.3% had good infection prevention practice. Being unemployed [AOR = 7.57, 95% CI (1.98, 28.93)], being a farmer [AOR = 2.73, 95% CI (1.01, 7.41)], and having a body mass index (BMI) below 18.5 kg/m2 [AOR = 5.12, 95%CI (2.45, 10.68)] were significantly associated with typhoid fever infection.

Conclusion

The prevalence of typhoid fever among febrile patients was high. Typhoid fever infection was significantly associated with occupational status (being unemployed and being a farmer) and lower BMI. The level of knowledge, perception, and practice of typhoid fever infection prevention were found inadequate. Therefore, behavioral change interventions are needed at the community level.

Defunctioning ileostomy for typhoid ileal perforations: Out of the frying pan into the fire?

Typhoid ileal perforation (TIP) is a common surgical emergency in low-middle income countries (LMICs). Its high surgical morbidity and mortality is due to its often late presentation or diagnosis, the patient's malnutrition, severe peritoneal contamination and unavailability of intensive care in most peripheral hospitals. This prompted the philosophy of minimizing the crisis by avoiding any repair or anastomosis, limiting the surgery in these physiologically compromised patients and performing only a temporary defunctioning ileostomy (DI) which could then be closed 10-12 weeks later.

Enteric Fever-Associated Hemophagocytic Lymphohistiocytosis: A Systematic Review of Clinical Characteristics and Outcomes

Enteric fever is a major contributor to rising health care costs in developing countries. Associated disease-related complications and drug resistance further compound this problem. Hemophagocytic lymphohistiocytosis (HLH) is an uncommon complication of enteric fever with high morbidity and mortality. This systematic review aimed to evaluate the clinical characteristics and treatment outcomes in enteric fever-associated HLH syndrome. We searched major electronic databases (PubMed, Google Scholar, and Scopus) to identify the cases of enteric fever associated with HLH from inception until June 2023. Prespecified data regarding clinical presentation, outcomes, and HLH therapy were collected. A total of 53 cases of enteric fever with HLH were included in the final analysis. The mean age of patients was 20 years, and the proportions of female and pediatric patients were 52.8% and 45.3%, respectively. The mean duration of illness was 10.4 days. A total of 39.6% of patients had enteric fever-associated complications; coagulopathy and encephalopathy were the most common (23.1% and 13.5%). The overall mortality rate was 9.4% in HLH. A total of 51% of patients received HLH-specific therapy (corticosteroids in 41.5% and intravenous immunoglobulin in 20.8% of patients). On multivariate analysis, high ferritin levels (≥5,000 ng/mL) were significantly associated with mortality (hazard ratio, 3.01; 95% CI = 0.62-14.12, P = 0.041). Enteric fever with secondary HLH is associated with high mortality. This review reveals the potential role of ferritin in disease prognosis. In cases with significantly elevated ferritin levels, the role of immunosuppressants or combination antibiotics should be explored.

Evolving Epidemiology and Antibiotic Resistance in Enteric Fever: A Comprehensive Review

Enteric fever, predominantly caused by Salmonella enterica serovar Typhi and Salmonella enterica serovar Paratyphi, remains a significant global health challenge. This comprehensive review examines the evolving epidemiology and antibiotic resistance associated with enteric fever. We provide an overview of the disease's definition and historical context, highlighting the substantial impact of antibiotic resistance on treatment efficacy. The review details the global burden, incidence trends, and risk factors of enteric fever while elucidating the pathogenesis and clinical manifestations of the disease. A critical analysis of antibiotic resistance mechanisms reveals the alarming rise of multi-drug resistant (MDR) and extensively drug-resistant (XDR) strains, complicating treatment regimens and underscoring the need for novel therapeutic strategies. Current treatment protocols, the role of empirical therapy, and the rational use of antibiotics are discussed in depth. Additionally, we explore prevention and control strategies, emphasizing the importance of vaccination programs, sanitation improvements, and effective public health interventions. The review concludes with recommendations for future actions, including enhanced surveillance, research and development of new antibiotics, expansion of vaccination efforts, and improved public health infrastructure. The findings highlight the necessity for updated clinical guidelines and sustained global efforts to address the challenges of enteric fever and its evolving antibiotic resistance patterns. Through coordinated action and continued innovation, it is possible to mitigate the impact of this enduring public health threat.

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

BACKGROUND

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.

METHODS

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.

FINDINGS

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.

INTERPRETATION

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.

FUNDING

The Bill & Melinda Gates Foundation.

Typhoid intestinal perforation in Francophone Africa, a scoping review

Typhoid intestinal perforation (TIP) is a leading cause of peritonitis and indication for emergency surgery in Africa, with reported mortality rates up to 30% in pediatric patients. Currently, data on TIP in Western databases are primarily from countries that speak English, likely due to non-English publication and citation biases. Despite the high burden of infectious diseases in Francophone Africa, data from these countries regarding TIP remain limited. This study aims to highlight the incidence and morbidity of TIP in Francophone African countries using an extended search algorithm. We conducted a scoping review using the PubMed, EMBASE, and SCOPUS databases with the keywords "peritonitis", "non-traumatic ileal perforation", and "typhoid" in Francophone African countries. Additionally, we contacted surgeons in Africa and concurrently used citation chasing to obtain data not found in western databases. In total, 32 studies from 12 countries were identified and included in this review. A total of 22 publications were in French. Patient median age was 20 years and TIP caused a median of 35% of acute peritonitis cases. Mortality rates ranged from 6-37% (median: 16%). Rate of complications ranged from 15-92% (median: 46%). Ileostomy creation as a treatment for TIP varied between hospitals (0-79%), with the highest rates reported in Niger. In Francophone Africa, TIP is associated with high morbidity and mortality, most commonly in children and young adults. Interventions, including improved sanitation and the introduction of typhoid conjugate vaccines into routine vaccination programs, have the potential to significantly decrease typhoid fever and its complications.

β-lactam-induced OMV release promotes polymyxin tolerance in Salmonella enterica sv. Typhi

The rise of multidrug-resistant bacteria is a global concern, leading to a renewed reliance on older antibiotics like polymyxins as a last resort. Polymyxins, cationic cyclic peptides synthesized nonribosomally, feature a hydrophobic acyl tail and positively charged residues. Their antimicrobial mechanism involves initial interaction with Gram-negative bacterial outer-membrane components through polar and hydrophobic interactions. Outer membrane vesicles (OMVs), nano-sized proteoliposomes secreted from the outer membrane of Gram-negative bacteria, play a crucial role in tolerating harmful molecules, including cationic peptides such as polymyxins. Existing literature has documented environmental changes' impact on modulating OMV properties in Salmonella Typhimurium. However, less information exists regarding OMV production and characteristics in Salmonella Typhi. A previous study in our laboratory showed that S. Typhi ΔmrcB, a mutant associated with penicillin-binding protein (PBP, a β-lactam antibiotic target), exhibited hypervesiculation. Consequently, this study investigated the potential impact of β-lactam antibiotics on promoting polymyxin tolerance via OMVs in S. Typhi. Our results demonstrated that sub-lethal doses of β-lactams increased bacterial survival against polymyxin B in S. Typhi. This phenomenon stems from β-lactam antibiotics inducing hypervesiculation of OMVs with higher affinity for polymyxin B, capturing and diminishing its biologically effective concentration. These findings suggest that β-lactam antibiotic use may inadvertently contribute to decreased polymyxin effectivity against S. Typhi or other Gram-negative bacteria, complicating the effective treatment of infections caused by these pathogens. This study emphasizes the importance of evaluating the influence of β-lactam antibiotics on the interaction between OMVs and other antimicrobial agents.

Case Report: A Case of Complicated Typhoid Fever with Rhabdomyolysis and Hemophagocytic Lymphohistiocytosis

Typhoid fever can have diverse extra-intestinal complications including encephalitis, Guillain-Barré syndrome, endocarditis, myocarditis, osteomyelitis, renal abscess, and splenic abscesses. Secondary hemophagocytic lymphohistiocytosis with rhabdomyolysis is a rare complication of typhoid fever. Here, we present the case of an adolescent with typhoid fever complicated by rhabdomyolysis and hemophagocytic lymphohistiocytosis.

Antimicrobial properties of tomato juice and peptides against typhoidal Salmonella

Tomatoes are readily available and affordable vegetables that offer a range of health benefits due to their bioactive molecules, such as antioxidants and antimicrobials. In contrast to the widely recognized antioxidant properties of tomatoes, their antimicrobial properties remain largely unexplored. Here, we present our findings on the antimicrobial properties of tomato juice and peptides, namely, tomato-derived antimicrobial peptides (tdAMPs), in relation to their effectiveness against typhoidal Salmonella. Our research has revealed that tomato juice demonstrates significant antimicrobial properties against Salmonella Typhi, a pathogen that specifically affects humans and is responsible for causing typhoid fever. By employing computational analysis of the tomato genome sequence, conducting molecular dynamics simulation, and performing functional analyses, we have successfully identified two tdAMPs, namely, tdAMP-1 and tdAMP-2. These tdAMPs have demonstrated potent antimicrobial properties by effectively disrupting bacterial membranes. The efficacy of tdAMP-2 is shown to be more effective than tdAMP-1. The efficacy of tdAMP-1 and tdAMP-2 has been demonstrated against drug-resistant S. Typhi, as well as hyper-capsular S. Typhi variants that possess hypervirulent characteristics, which are presently circulating in countries with endemicity. Tomato juice, along with the two tdAMPs, has demonstrated effectiveness against uropathogenic Escherichia coli as well. This underscores their potential as viable agents in combating certain Gram-negative pathogens. This study provides valuable insights into the development of effective and sustainable public health strategies that utilize tomato and its derivatives as lifestyle interventions.IMPORTANCEIn this study, we investigate the antimicrobial properties of tomato juice, the most widely consumed affordable vegetables, as well as tomato-derived antimicrobial peptides, in relation to their effectiveness against foodborne pathogens with an emphasis on Salmonella Typhi, a deadly human-specific pathogen.

A Prolonged Outbreak of Enteric Fever Associated With Illegal Miners in the City of Matlosana, South Africa, November 2020-September 2022

Background

In South Africa, the annual incidence of enteric fever averaged 0.1 per 100 000 persons between 2003 and 2018. During 2021 an increase in the number of enteric fever cases was observed. An outbreak investigation was conducted to determine the magnitude and source of the outbreak.

Methods

We performed a cross-sectional descriptive study. Data were collected through telephonic or face-to-face interviews with cases or proxies via a standardized case investigation form. Whole genome sequencing was performed on all Salmonella Typhi isolates. Drinking water samples were collected, tested, and analyzed. Descriptive analysis was performed with Microsoft Excel.

Results

Between January 2020 and September 2022, a cluster of 53 genetically highly related Salmonella Typhi isolates was identified from 5 provinces in South Africa. Isolates associated with the cluster showed ≤5 allelic differences, as determined following core genome multilocus sequence typing analysis. Most cases (60%, 32/53) were in the North West province. Males represented 68% (36/53). Of these, 72% (26/36) were aged 15 to 49 years, with a median age of 31 years. Where occupation was known within this age group, 78% (14/18) were illegal gold miners. Illegal miners reported illness onset while working underground. Five municipal tap water samples were tested and showed no evidence of fecal contamination.

Conclusions

This outbreak predominantly affected illegal gold miners, likely due to the consumption of contaminated groundwater while working in a gold mine shaft. In addition, this investigation highlights the value of whole genome sequencing to detect clusters and support epidemiologic investigation of enteric fever outbreaks.

Typhoid Conjugate Vaccine: A Boon for Endemic Regions

Typhoid fever has the highest disease burden in countries in low- and middle-income countries, primarily located in Asia and Sub-Saharan Africa. Previous typhoid vaccines such as the live attenuated typhoid (Ty21a) vaccine and Vi (virulence) capsular polysaccharide vaccine had the limitation that they could not be administered with other standard childhood immunizations and were ineffective in children under two years of age. To address these shortcomings of the previous vaccines, typhoid conjugate vaccines (TCVs) were developed and prequalified by the World Health Organization. Cross-reacting material and tetanus toxoid are widely used as carrier proteins in TCVs. According to various studies, TCV has higher efficacy, has a more extended protection period, and is safe and immunogenic in infants as young as six months. This review article aims to comprehensively appraise the data available on TCVs' efficacy, duration of protection, safety, and immunogenicity in endemic regions.

Efficacy of typhoid conjugate vaccine: final analysis of a 4-year, phase 3, randomised controlled trial in Malawian children

BACKGROUND

Randomised controlled trials of typhoid conjugate vaccines among children in Africa and Asia have shown high short-term efficacy. Data on the durability of protection beyond 2 years are sparse. We present the final analysis of a randomised controlled trial in Malawi, encompassing more than 4 years of follow-up, with the aim of investigating vaccine efficacy over time and by age group.

METHODS

In this phase 3, double-blind, randomised controlled efficacy trial in Blantyre, Malawi, healthy children aged 9 months to 12 years were randomly assigned (1:1) by an unmasked statistician to receive a single dose of Vi polysaccharide conjugated to tetanus toxoid vaccine (Vi-TT) or meningococcal capsular group A conjugate (MenA) vaccine. Children had to have no previous history of typhoid vaccination and reside in the study areas for inclusion and were recruited from government schools and health centres. Participants, their parents or guardians, and the study team were masked to vaccine allocation. Nurses administering vaccines were unmasked. We did surveillance for febrile illness from vaccination until follow-up completion. The primary outcome was first occurrence of blood culture-confirmed typhoid fever. Eligible children who were randomly assigned and vaccinated were included in the intention-to-treat analyses. This trial is registered at ClinicalTrials.gov, NCT03299426.

FINDINGS

Between Feb 21, 2018, and Sept 27, 2018, 28 130 children were vaccinated; 14 069 were assigned to receive Vi-TT and 14 061 to receive MenA. After a median follow-up of 4·3 years (IQR 4·2-4·5), 24 (39·7 cases per 100 000 person-years) children in the Vi-TT group and 110 (182·7 cases per 100 000 person-years) children in the MenA group were diagnosed with a first episode of blood culture-confirmed typhoid fever. In the intention-to-treat population, efficacy of Vi-TT was 78·3% (95% CI 66·3-86·1), and 163 (129-222) children needed to be vaccinated to prevent one case. Efficacies by age group were 70·6% (6·4-93·0) for children aged 9 months to 2 years; 79·6% (45·8-93·9) for children aged 2-4 years; and 79·3% (63·5-89·0) for children aged 5-12 years.

INTERPRETATION

A single dose of Vi-TT is durably efficacious for at least 4 years among children aged 9 months to 12 years and shows efficacy in all age groups, including children younger than 2 years. These results support current WHO recommendations in typhoid-endemic areas for mass campaigns among children aged 9 months to 15 years, followed by routine introduction in the first 2 years of life.

FUNDING

Bill & Melinda Gates Foundation.

Typhoid fever

Typhoid fever is an invasive bacterial disease associated with bloodstream infection that causes a high burden of disease in Africa and Asia. Typhoid primarily affects individuals ranging from infants through to young adults. The causative organism, Salmonella enterica subsp. enterica serovar Typhi is transmitted via the faecal-oral route, crossing the intestinal epithelium and disseminating to systemic and intracellular sites, causing an undifferentiated febrile illness. Blood culture remains the practical reference standard for diagnosis of typhoid fever, where culture testing is available, but novel diagnostic modalities are an important priority under investigation. Since 2017, remarkable progress has been made in defining the global burden of both typhoid fever and antimicrobial resistance; in understanding disease pathogenesis and immunological protection through the use of controlled human infection; and in advancing effective vaccination programmes through strategic multipartner collaboration and targeted clinical trials in multiple high-incidence priority settings. This Primer thus offers a timely update of progress and perspective on future priorities for the global scientific community.

Population structure of Salmonella enterica Typhi in Harare, Zimbabwe (2012-19) before typhoid conjugate vaccine roll-out: a genomic epidemiology study

BACKGROUND

The continued emergence of Salmonella enterica serovar Typhi, with ever increasing antimicrobial resistance, necessitates the use of vaccines in endemic countries. A typhoid fever outbreak in Harare, Zimbabwe, in 2018 from a multidrug resistant S Typhi with additional resistance to ciprofloxacin was the catalyst for the introduction of a typhoid conjugate vaccine programme. We aimed to investigate the emergence and evolution of antimicrobial resistance of endemic S Typhi in Zimbabwe and to determine the population structure, gene flux, and sequence polymorphisms of strains isolated before a typhoid conjugate vaccine programme to provide a baseline for future evaluation of the effect of the vaccination programme.

METHODS

In this genomic epidemiology study, we used short-read whole-genome sequencing of S Typhi isolated from clinical cases of typhoid fever in Harare, Zimbabwe, between Jan 1, 2012, and Feb 9, 2019, to determine the S Typhi population structure, gene flux, and sequence polymorphisms and reconstructed the evolution of antimicrobial resistance. Maximum likelihood time-scaled phylogenetic trees of Zimbabwe isolates in the context of global isolates obtained from the National Center for Biotechnology Information were constructed to infer spread and emergence of antimicrobial resistance.

FINDINGS

The population structure of S Typhi in Harare, Zimbabwe, from 2012 to 2019 was dominated by multidrug resistant genotype 4.3.1.1.EA1 (H58) that spread to Zimbabwe from neighbouring countries in around 2009 (95% credible interval 2008·5-2010·0). Acquisition of an IncN plasmid carrying antimicrobial resistance genes including a qnrS gene and a mutation in the quinolone resistance determining region of gyrA gene contributed to non-susceptibility and resistance to quinolone antibiotics. A minority population of antimicrobial susceptible S Typhi genotype 3.3.1 strains were present throughout.

INTERPRETATION

The currently dominant S Typhi population is genotype 4.3.1.1 that spread to Zimbabwe and acquired additional antimicrobial resistance though acquisition of a plasmid and mutation in the gyrA gene. This study provides a baseline population structure for future evaluation of the effect of the typhoid conjugate vaccine programme in Harare.

FUNDING

Bill & Melinda Gates Foundation and the Biotechnology and Biological Sciences Research Council Institute Strategic Programme.

Association Among Household Water, Sanitation, and Hygiene (WASH) Status and Typhoid Risk in Urban Slums: Prospective Cohort Study in Bangladesh

BACKGROUND

Typhoid fever, or enteric fever, is a highly fatal infectious disease that affects over 9 million people worldwide each year, resulting in more than 110,000 deaths. Reduction in the burden of typhoid in low-income countries is crucial for public health and requires the implementation of feasible water, sanitation, and hygiene (WASH) interventions, especially in densely populated urban slums.

OBJECTIVE

In this study, conducted in Mirpur, Bangladesh, we aimed to assess the association between household WASH status and typhoid risk in a training subpopulation of a large prospective cohort (n=98,087), and to evaluate the performance of a machine learning algorithm in creating a composite WASH variable. Further, we investigated the protection associated with living in households with improved WASH facilities and in clusters with increasing prevalence of such facilities during a 2-year follow-up period.

METHODS

We used a machine learning algorithm to create a dichotomous composite variable ("Better" and "Not Better") based on 3 WASH variables: private toilet facility, safe drinking water source, and presence of water filter. The algorithm was trained using data from the training subpopulation and then validated in a distinct subpopulation (n=65,286) to assess its sensitivity and specificity. Cox regression models were used to evaluate the protective effect of living in "Better" WASH households and in clusters with increasing levels of "Better" WASH prevalence.

RESULTS

We found that residence in households with improved WASH facilities was associated with a 38% reduction in typhoid risk (adjusted hazard ratio=0.62, 95% CI 0.49-0.78; P<.001). This reduction was particularly pronounced in individuals younger than 10 years at the first census participation, with an adjusted hazard ratio of 0.49 (95% CI 0.36-0.66; P<.001). Furthermore, we observed an inverse relationship between the prevalence of "Better" WASH facilities in clusters and the incidence of typhoid, although this association was not statistically significant in the multivariable model. Specifically, the adjusted hazard of typhoid decreased by 0.996 (95% CI 0.986-1.006) for each percent increase in the prevalence of "Better" WASH in the cluster (P=.39).

CONCLUSIONS

Our findings demonstrate that existing variations in household WASH are associated with differences in the risk of typhoid in densely populated urban slums. This suggests that attainable improvements in WASH facilities can contribute to enhanced typhoid control, especially in settings where major infrastructural improvements are challenging. These findings underscore the importance of implementing and promoting comprehensive WASH interventions in low-income countries as a means to reduce the burden of typhoid and improve public health outcomes in vulnerable populations.

Cost-effectiveness analysis of typhoid vaccination in Lao PDR

BACKGROUND

Typhoid vaccination has been shown to be an effective intervention to prevent enteric fever and is under consideration for inclusion in the national immunization program in Lao PDR.

METHODS

A cost-utility analysis was performed using an age-structured static decision tree model to estimate the costs and health outcomes of introducing TCV. Vaccination strategies combined with five delivery approaches in different age groups compared to no vaccination were considered from the societal perspective, using the Gavi price of 1.5 USD per dose. The vaccination program was considered to be cost-effective if the incremental cost-effectiveness ratio was less than a threshold of 1 GDP per capita for Lao PDR, equivalent to USD 2,535 in 2020.

RESULTS

In the model, we estimated 172.2 cases of enteric fever, with 1.3 deaths and a total treatment cost of USD 7,244, based on a birth cohort of 164,662 births without TCV vaccination that was followed over their lifetime. To implement a TCV vaccination program over the lifetime horizon, the estimated cost of the vaccine and administration costs would be between USD 470,934 and USD 919,186. Implementation of the TCV vaccination program would prevent between 14 and 106 cases and 0.1 to 0.8 deaths. None of the vaccination programs appeared to be cost-effective.

CONCLUSIONS

Inclusion of TCV in the national vaccination program in Lao PDR would only be cost-effective if the true typhoid incidence is 25-times higher than our current estimate.

Plasmodium knowlesi (Pk) Malaria: A Review & Proposal of Therapeutically Rational Exchange (T-REX) of Pk-Resistant Red Blood Cells

Plasmodium knowlesi (Pk) causes zoonotic malaria and is known as the "fifth human malaria parasite". Pk malaria is an emerging threat because infections are increasing and can be fatal. While most infections are in Southeast Asia (SEA), especially Malaysia, travelers frequently visit this region and can present with Pk malaria around the world. So, clinicians need to know (1) patients who present with fever after recent travel to SEA might be infected with Pk and (2) Pk is often misdiagnosed as P. malariae (which typically causes less severe malaria). Here we review the history, pathophysiology, clinical features, diagnosis, and treatment of Pk malaria. Severe disease is most common in adults. Signs and symptoms can include fever, abdominal pain, jaundice, acute kidney injury, acute respiratory distress syndrome, hyponatremia, hyperparasitemia, and thrombocytopenia. Dengue is one of the diseases to be considered in the differential. Regarding pathophysiologic mechanisms, when Pk parasites invade mature red blood cells (RBCs, i.e., normocytes) and reticulocytes, changes in the red blood cell (RBC) surface can result in life-threatening cytoadherence, sequestration, and reduced RBC deformability. Since molecular mechanisms involving the erythrocytic stage are responsible for onset of severe disease and lethal outcomes, it is biologically plausible that manual exchange transfusion (ET) or automated RBC exchange (RBCX) could be highly beneficial by replacing "sticky" parasitized RBCs with uninfected, deformable, healthy donor RBCs. Here we suggest use of special Pk-resistant donor RBCs to optimize adjunctive manual ET/RBCX for malaria. "Therapeutically-rational exchange transfusion" (T-REX) is proposed in which Pk-resistant RBCs are transfused (instead of disease-promoting RBCs). Because expression of the Duffy antigen on the surface of human RBCs is essential for parasite invasion, T-REX of Duffy-negative RBCs-also known as Fy(a-b-) RBCs-could replace the majority of the patient's circulating normocytes with Pk invasion-resistant RBCs (in a single procedure lasting about 2 h). When sequestered or non-sequestered iRBCs rupture-in a 24 h Pk asexual life cycle-the released merozoites cannot invade Fy(a-b-) RBCs. When Fy(a-b-) RBC units are scarce (e.g., in Malaysia), clinicians can consider the risks and benefits of transfusing plausibly Pk-resistant RBCs, such as glucose-6-phosphate dehydrogenase deficient (G6PDd) RBCs and Southeast Asian ovalocytes (SAO). Patients typically require a very short recovery time (<1 h) after the procedure. Fy(a-b-) RBCs should have a normal lifespan, while SAO and G6PDd RBCs may have mildly reduced half-lives. Because SAO and G6PDd RBCs come from screened blood donors who are healthy and not anemic, these RBCs have a low-risk for hemolysis and do not need to be removed after the patient recovers from malaria. T-REX could be especially useful if (1) antimalarial medications are not readily available, (2) patients are likely to progress to severe disease, or (3) drug-resistant strains emerge. In conclusion, T-REX is a proposed optimization of manual ET/RBCX that has not yet been utilized but can be considered by physicians to treat Pk malaria patients.

Variations of blood viscosity in acute typhoid fever: A cross-sectional study

Typhoid fever (TF) is a systemic infection caused by Salmonella Typhi (Salmonella Enterica) transmitted through contaminated water, food, or contact with infected individuals. In various infectious diseases, blood viscosity (BV) is affected by changes in hemoglobin concentrations and acute phase reactants. Inflammatory responses can lead to elevated plasma protein levels and further affect BV. This study aimed to investigate BV changes in patients with acute TF. A cross-sectional study was performed involving 55 patients with acute TF compared to 38 healthy controls. BV and inflammatory parameters were measured in both groups. TF patients showed reduced blood cells compared to healthy controls (p=0.001). Additionally, plasma total protein (TP) levels significantly increased to 10.79±1.05 g/L in TF patients compared to 7.035±1.44 g/L in healthy controls (p=0.03). Hematocrit (HCT) levels were 11.67±2.89% in TF patients and 12.84±2.02% in healthy controls (p=0.07), suggesting a trend towards increased BV in TF patients. Elevated BV is involved in the pathogenesis of different inflammatory and infectious diseases. The increased BV in TF patients may raise the risk of complications. Therefore, monitoring BV might be a crucial tool in TF patients, mainly in the high-risk group, for early detection of cardiovascular complications.

Differential regulatory control of curli (csg) gene expression in Salmonella enterica serovar Typhi requires more than a functional CsgD regulator

The human-specific Salmonella enterica serovar Typhi (S. Typhi) causes typhoid fever, a systemic disease with no known reservoir. Curli fimbriae are major components of biofilm produced by Salmonella and are encoded by the csg gene cluster (csgBAC and csgDEFG). The role of curli in S. Typhi is unknown, although detection of anti-curli antibodies suggests they are produced during host infection. In this study, we investigated curli gene expression in S. Typhi. We demonstrated that the CsgD regulatory protein binds weakly to the csgB promoter. Yet, replacing S. Typhi csgD with the csgD allele from S. Typhimurium did not modify the curli negative phenotype on Congo Red medium suggesting that differential regulation of curli gene expression in S. Typhi is not dependent on modification of the CsgD regulator. The entire csg gene cluster from S. Typhimurium was also cloned into S. Typhi, but again, despite introduction of a fully functional csg gene cluster from S. Typhimurium, curli were still not detected in S. Typhi. Thus, in addition to intrinsic genomic differences in the csg gene cluster that have resulted in production of a modified CsgD protein, S. Typhi has likely undergone other changes independent of the csg gene cluster that have led to distinctive regulation of csg genes compared to other Salmonella serovars.

Enteric Fever: Diagnostic Challenges and the Importance of Early Intervention

Enteric fever is a systemic infection caused by highly virulent Salmonella enterica serovars: Typhi and Paratyphi. Diagnosis of enteric fever is challenging due to a wide variety of clinical features which overlap with other febrile illnesses. The current diagnostic methods are limited because of the suboptimal sensitivity of conventional tests like blood culture in detecting organisms and the invasive nature of bone marrow culture. It emphasizes the need to develop improved and more reliable diagnostic modalities. The rising rates of multidrug-resistant Salmonella strains call for an accurate understanding of the current management of the disease. Proper public health measures and large-scale immunization programs will help reduce the burden of the disease. A comprehensive surveillance system can help detect the chronic carrier state and is crucial in understanding antibiotic susceptibility patterns. We conducted an all-language literature search on Medline, Cochrane, Embase, and Google Scholar till May 2022. The following search words and medical subject headings (MeSH) were used: "enteric fever," "Salmonella Typhi," "multidrug-resistant Salmonella," chronic carrier state," "Salmonella detection, "and "typhoid vaccine." We reviewed the literature on clinical features, pathophysiology, new diagnostic tests, and interventions to prevent the disease. This article explores enteric fever and its various clinical features and addresses the emerging threat of multidrug resistance. It focuses on novel methods for diagnosis and prevention strategies, including vaccines and the use of surveillance systems employed across different parts of the world.

Fatal Complications of Extensive Drug-Resistant Typhoid Fever: A Case Report

Typhoid fever is a systemic illness that often presents with fever, abdominal pain, and diarrhea. There are multiple complications associated with typhoid fever which includes intestinal perforation, gastrointestinal hemorrhage, hepatitis, and anemia. In recent years, a new extensively drug resistant (XDR) strain of Salmonella typhi (S. typhi) emerged, associated with higher incidence of complications, responding to azithromycin and carbapenems only. In this article, we report a case of a 28-year-old Pakistani male who initially presented with fever and bloody diarrhea, complicated by massive lower gastrointestinal bleed, leading to his mortality. This case, being the first reported case in Bahrain, illustrates the importance of considering hepatic manifestations and lower gastrointestinal bleeding as fatal complications of typhoid fever, especially in the setting of recent travel to Southeast Asia.

Association of Biochemical and Hematological Parameters With Enteric Fever Infection at the Dschang Regional Annex Hospital, Cameroon: A Cross-Sectional Study

Background Enteric fever is a systemic infection in humans caused by the Gram-negative bacilliSalmonella enterica serovars Typhi and Paratyphi. Although the diagnosis typically involves the isolation of Salmonella enterica serovars, it is often determined based on laboratory findings and clinical observations. However, due to the wide variety and the non-specific character of clinical features, making a definitive diagnosis presents numerous challenges. Therefore, the aim of this study was to find the predictive hematological and biochemical parameters which would serve in the diagnosis, prognosis, and treatment of typhoid fever cases. Methodology A cross-sectional study was conducted from November 2020 to September 2021 on1076consented volunteerparticipants. Stool culture and identification tests enabled us to distinguish three groups including 423 Salmonella Typhi positive patients, 115 S. Paratyphi positive patients, and 538 Salmonella negative participants. Biochemical and hematological parameters were evaluated using standard methods from commercial kits and Sysmex KX-21N automated hematology analyzer, respectively. A multiple logistic regression analysis was performed to identify the validity of the hematological and biochemical characteristics for enteric fever diagnosis. Results Multiple logistic regression showed hyper creatininemia, hypoalbuminemia, hyper total proteinemia, hyper alkaline phosphatase (ALP), hyper alanine aminotransferase (ALT), hyper total bilirubinemia, hyper conjugated bilirubinemia, hyper triglyceridemia, hyper C-reactive protein (CRP), leukopenia, thrombocytopenia, lymphopenia, monocytopenia, low hemoglobin, low hematocrit, low mean corpuscular volume (MCV), low mean corpuscular hemoglobin (MCH), low platelet, low platelet crit level, high platelet distribution width (PDW) level, high erythrocyte sedimentation rate 1 (ESR1) level as significant biological abnormalities associated (odds ratio {OR} > 1; p < 0.05) with enteric fever infection. Similarly, hyper ESR2 was an independent predictor (OR > 1; p < 0.05) of S. Typhi infection. However, a negative and significant association (OR < 1; p < 0.05) was recorded between enteric fever infection and high mean platelet volume (MPV). Conclusion Overall the results of the biochemical and hematological profiles can serve as potential diagnostic markers for typhoid fever. These markers can also be useful in the appropriate management of those with enteric fever, preventing severity and limiting outcomes of mortality.

Characterization of Typhoid Intestinal Perforation in Africa: Results From the Severe Typhoid Fever Surveillance in Africa Program

Background

Typhoid intestinal perforation (TIP) remains the most serious complication of typhoid fever. In many countries, the diagnosis of TIP relies on intraoperative identification, as blood culture and pathology capacity remain limited. As a result, many cases of TIP may not be reported as typhoid. This study demonstrates the burden of TIP in sites in Burkina Faso, Democratic Republic of Congo (DRC), Ethiopia, Ghana, Madagascar, and Nigeria.

Methods

Patients with clinical suspicion of nontraumatic intestinal perforation were enrolled and demographic details, clinical findings, surgical records, blood cultures, tissue biopsies, and peritoneal fluid were collected. Participants were then classified as having confirmed TIP, probable TIP, possible TIP, or clinical intestinal perforation based on surgical descriptions and cultures.

Results

A total of 608 participants were investigated for nontraumatic intestinal perforation; 214 (35%) participants had surgically-confirmed TIP and 33 participants (5%) had culture-confirmed typhoid. The overall proportion of blood or surgical site Salmonella enterica subspecies enterica serovar Typhi positivity in surgically verified TIP cases was 10.3%. TIP was high in children aged 5-14 years in DRC, Ghana, and Nigeria. We provide evidence for correlation between monthly case counts of S. Typhi and the occurrence of intestinal perforation.

Conclusions

Low S. Typhi culture positivity rates, as well as a lack of blood and tissue culture capability in many regions where typhoid remains endemic, significantly underestimate the true burden of typhoid fever. The occurrence of TIP may indicate underlying typhoid burden, particularly in countries with limited culture capability.

Cost-effectiveness analysis of typhoid conjugate vaccines in an outbreak setting: a modeling study

BACKGROUND

Several prolonged typhoid fever epidemics have been reported since 2010 throughout eastern and southern Africa, including Malawi, caused by multidrug-resistant Salmonella Typhi. The World Health Organization recommends the use of typhoid conjugate vaccines (TCVs) in outbreak settings; however, current data are limited on how and when TCVs might be introduced in response to outbreaks.

METHODOLOGY

We developed a stochastic model of typhoid transmission fitted to data from Queen Elizabeth Central Hospital in Blantyre, Malawi from January 1996 to February 2015. We used the model to evaluate the cost-effectiveness of vaccination strategies over a 10-year time horizon in three scenarios: (1) when an outbreak is likely to occur; (2) when an outbreak is unlikely to occur within the next ten years; and (3) when an outbreak has already occurred and is unlikely to occur again. We considered three vaccination strategies compared to the status quo of no vaccination: (a) preventative routine vaccination at 9 months of age; (b) preventative routine vaccination plus a catch-up campaign to 15 years of age; and (c) reactive vaccination with a catch-up campaign to age 15 (for Scenario 1). We also explored variations in outbreak definitions, delays in implementation of reactive vaccination, and the timing of preventive vaccination relative to the outbreak.

RESULTS

Assuming an outbreak occurs within 10 years, we estimated that the various vaccination strategies would prevent a median of 15-60% of disability-adjusted life-years (DALYs). Reactive vaccination was the preferred strategy for WTP values of $0-300 per DALY averted. For WTP values > $300, introduction of preventative routine TCV immunization with a catch-up campaign was the preferred strategy. Routine vaccination with a catch-up campaign was cost-effective for WTP values above $890 per DALY averted if no outbreak occurs and > $140 per DALY averted if implemented after the outbreak has already occurred.

CONCLUSIONS

Countries for which the spread of antimicrobial resistance is likely to lead to outbreaks of typhoid fever should consider TCV introduction. Reactive vaccination can be a cost-effective strategy, but only if delays in vaccine deployment are minimal; otherwise, introduction of preventive routine immunization with a catch-up campaign is the preferred strategy.

Evaluation of Genomic Typing Methods in the Salmonella Reference Laboratory in Public Health, England, 2012-2020

We aim to provide an evidence-based evaluation of whole genome sequence (WGS) methods, employed at the Salmonella reference laboratory in England, in terms of its impact on public health and whether these methods remain a fit for purpose test under UKAS ISO 15189. The evaluation of the genomic methods were mapped against the value of detecting microbiological clusters to support the investigation of food-borne outbreaks of Salmonella in England between 2012-2020. The analysis of WGS with both SNP- and allelic-based methods provided an unprecedented level of strain discrimination and detection of additional clusters when comparing to all of the previous typing methods. The robustness of the routine genomic sequencing at the reference laboratory ensured confidence in the microbiological identifications, even in large outbreaks with complex international food distribution networks. There was evidence that the phylogeny derived from the WGS data can be used to inform the provenance of strains and support discrimination between domestic and non-domestic transmission events. Further insight on the evolutionary context of the emerging pathogenic strains was enabled with a deep dive of the phylogenetic data, including the detection of nested clusters. The public availability of the WGS data linked to the clinical, epidemiological and environmental context of the sequenced strains has improved the trace-back investigations during outbreaks. The global expansion in the use of WGS-based typing in reference laboratories has shown that the WGS methods are a fit for purpose test in public health as it has ensured the rapid implementation of interventions to protect public health, informed risk assessment and has facilitated the management of national and international food-borne outbreaks of Salmonella.

Molecular Characterization of Extensively Drug Resistant Salmonella Enterica Serovar Typhi Clinical Isolates from Lahore, Pakistan

Background

The emergence of extensively drug-resistant (XDR) typhoid in Pakistan has endangered the treatment options available to manage this infection. Third generation cephalosporin were the empiric choice to treat typhoid fever in Pakistan, but acquisition of ESBLs have knocked them out of the arsenal. The current empiric choice is azithromycin which is vulnerable to resistance too. This study aimed to assess the burden of XDR typhoid and the frequency of resistance determinants in blood culture samples collected from different hospitals in Lahore, Pakistan.

Methods

A total of 835 blood cultures were collected from different tertiary care hospitals in Lahore during January 2019 to December 2021. Among 835 blood cultures, 389 Salmonella Typhi were identified, and 150 were XDR S. Typhi (resistant to all recommended antibiotics). Antibiotics resistance genes of the first-line drugs (bla_TEM-1, catA1, sul1, and dhfR7) and second line drugs (gyrB, gyrA, qnrS, ParC and ParE) were investigated among XDR S. Typhi. There were different CTX-M genes isolated using the specific primers, bla_CTX-M-U, bla_CTX-M-1, bla_CTX-M-15, bla_CTX-M-2, bla_CTX-M-8 and bla_CTX-M-9.

Results

Antibiotic resistant genes of the first-line drugs were isolated with different frequency, bla_TEM-1 (72.6%), catA1 (86.6%), sul1 (70%), and dhfR7 (56%). Antibiotics resistance genes of second-line drugs were isolated as: gyrB (60%), gyrA (49.3%), qnrS (32.6%), parC (44%) and parE (28%). Among CTX-M genes, bla_CTX-M-U (63.3%) was the most frequent followed by bla_CTX-M-15 (39.3%) and bla_CTX-M-1 (26%).

Conclusion

Our study concluded that XDR isolates circulating in Pakistan have acquired first-line and second-line antibiotic resistant genes quite successfully along with CTX-M genes (ESBLs) rendering them resistant to the third generation cephalosporins as well. Emergence of azithromycin resistance in XDR S. Typhi which is currently used as an empiric treatment option is worrisome and needs to be monitored carefully in endemic countries like Pakistan.

Clinical and Laboratory Features of Enteric Fever in Children and Antibiotic Sensitivity Pattern in a Tertiary Care Hospital of a Low- and Middle-Income Country

BACKGROUND

Globally, enteric fever (EF) significantly gives rise to an appalling death toll. It is an endemic illness in Bangladesh and South Asia. The condition manifests in a wide range of clinical features in children. Nowadays, antibiotic resistance is an international stumbling block that hampers the appropriate treatment and outcome of EF.

OBJECTIVE

The study evaluated the clinical and laboratory characteristics and antibiotic sensitivity pattern of Salmonella enterica in children.

METHODS

This prospective research was conducted at Delta Medical College and Hospital, Dhaka, Bangladesh, from January 2017 to December 2019. A total of 200 pediatric cases of EF were included in this study who were either culture positive or had significantly raised Widal test titer for Salmonella with suggestive clinical features.

RESULTS

All the patients had a fever, and most had coated tongue, vomiting, abdominal pain, organomegaly, and diarrhea. Among the selected 200 cases of EF, 43.5% were Salmonella typhi culture-positive. A high erythrocyte sedimentation rate (ESR) was observed in a substantial number (53%) of patients. Ceftriaxone was the most sensitive (100%) antibiotic through laboratory analysis, followed by cefotaxime (95.1%). Among the oral antibiotics used, cefixime (92.8%) was the most sensitive.

CONCLUSION

EF in children can present with varied clinical manifestations. Selective antibiotic treatment according to sensitivity patterns is crucial for effective illness management and will reduce morbidity and mortality in the pediatric population.

Clinical manifestations and microbiological features between indigenous and imported enteric fever in Taiwan, 2010-2020

Previous studies had showed that indigenous clones of Salmonella Typhi and S. Paratyphi were originally imported from other countries in Taiwan. We presented the clinical manifestations and laboratory findings of indigenous and imported enteric fever cases in Taiwan in the current decade. We retrospectively reviewed typhoid and paratyphoid fever cases in two medical centers of Chang Gung Memorial Hospitals in 2010-2020. A total of 37 enteric fever cases including 24 typhoid fever and 13 paratyphoid fever were recorded. There were 20 indigenous cases, 16 imported cases, and one indetermined case. Splenomegaly and hepatitis were more frequent in typhoid fever than in paratyphoid fever (P < 0.05). Imported cases had more ciprofloxacin non-susceptibility rate (8/16, 50.0%) than indigenous cases (2/20, 10%). Indigenous ciprofloxacin non-susceptible S. Typhi isolates were found in 2018. One indigenous S. Paratyphi B isolate was multi-drug resistant (MDR) to chloramphenicol, ampicillin, and trimethoprim/sulfamethoxazole.

Outpatient management of uncomplicated enteric fever: A case series of 93 patients from the Hospital of Tropical Diseases, London

OBJECTIVES

Enteric fever is predominantly managed as an outpatient condition in endemic settings but there is little evidence to support this approach in non-endemic settings. This study aims to review the outcomes of outpatients treated for enteric fever at the Hospital of Tropical Diseases in London, UK.

METHODS

We conducted a retrospective analysis of all patients with confirmed enteric fever between August 2009 and September 2020. Demographic, clinical, laboratory and microbiological data were collected and compared between the inpatient and outpatient populations. Outcomes investigated were complicated enteric fever, treatment failure and relapse.

RESULTS

Overall, 93 patients (59% male, median age 31) were identified with blood and/or stool culture confirmed enteric fever and 49 (53%) of these were managed as outpatients. The commonest empirical treatment for outpatients was azithromycin (70%) and for inpatients was ceftriaxone (84%). Outpatients were more likely than inpatients to receive only one antibiotic (57% vs 19%, p < 0.01) and receive a shorter duration of antibiotics (median 7 vs 11 days, p <0.01). There were no cases of complicated disease or relapse in either the inpatient or outpatient groups. There was one treatment failure in the outpatient group. Azithromycin was well-tolerated with no reported side effects.

CONCLUSIONS

Our findings suggest that outpatient management of uncomplicated imported enteric fever is safe and effective with the use of oral azithromycin. Careful monitoring of patients is recommended as treatment failure can occur.

Complications and mortality of non-typhoidal salmonella invasive disease: a global systematic review and meta-analysis

BACKGROUND

Non-typhoidal salmonella can cause serious, life-threatening invasive infections involving the bloodstream and other normally sterile sites. We aimed to systematically review the prevalence of complications and case-fatality ratio (CFR) of non-typhoidal salmonella invasive disease to provide contemporary global estimates and inform the development of vaccine and non-vaccine interventions.

METHODS

We did a global systematic review and meta-analysis of studies investigating the complications and mortality associated with non-typhoidal salmonella invasive disease. We searched Embase, MEDLINE, Web of Science, and PubMed for peer-reviewed, primary research articles published from database inception up to June 4, 2021, with no restrictions on language, country, date, or participant demographics. Only studies reporting the proportion of complications or deaths associated with non-typhoidal salmonella invasive disease, confirmed by culture of samples taken from a normally sterile site (eg, blood or bone marrow) were included. We excluded case reports, case series, policy reports, commentaries, editorials, and conference abstracts. Data on the prevalence of complications and CFR were abstracted. The primary outcomes were to estimate the prevalence of complications and CFR of non-typhoidal salmonella invasive disease. We calculated an overall pooled CFR estimate and pooled CFR stratified by UN region, subregion, age group, and by serovar when available with a random-effects meta-analysis. A risk-of-bias assessment was done, and heterogeneity was assessed with Cochran's Q Test, I2, and τ2. This study was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, and is registered with PROSPERO, CRD42020202293.

FINDINGS

The systematic review returned a total of 8770 records. After duplicates were removed, 5837 titles and abstracts were screened, yielding 84 studies from 35 countries after exclusions. Of these included studies, 77 (91·7%) were hospital-based and 66 (78·6%) were located in Africa or Asia. Among 55 studies reporting non-typhoidal salmonella disease-associated complications, a total of 45 different complications were reported and 1824 complication events were identified among 6974 study participants. The most prevalent complication was septicaemia, occurring in 171 (57·2%) of 299 participants, followed by anaemia in 580 (47·3%) of 1225 participants. From 81 studies reporting the CFR of non-typhoidal salmonella invasive disease, the overall pooled CFR estimate was 14·7% (95% CI 12·2-17·3). When stratified by UN region, the pooled CFR was 17·1% (13·6-21·0) in Africa, 14·0% (9·4-19·4) in Asia, 9·9% (6·4-14·0) in Europe, and 9·6% (0·0-25·1) in the Americas. Of all 84 studies, 66 (78·6%) had an overall high risk of bias, 18 (21·4%) had a moderate risk, and none had a low risk. Substantial heterogeneity (I2>80%) was observed in most (15 [65·2%] of 23) CFR estimates.

INTERPRETATION

Complications were frequent among individuals with non-typhoidal salmonella invasive disease and approximately 15% of patients died. Clinicians, especially in African countries, should be aware of non-typhoidal salmonella invasive disease as a cause of severe febrile illness. Prompt diagnoses and management decisions, including empiric antimicrobial therapy, would improve patient outcomes. Additionally, investments in improving clinical microbiology facilities to identify non-typhoidal salmonella and research efforts towards vaccine development and non-vaccine prevention measures would prevent non-typhoidal salmonella invasive disease-associated illness and death.

FUNDING

EU Horizon 2020 research and innovation programme.

MIS-C frenzy: The importance of considering a broad differential diagnosis

We report a case of a 3 year-old boy with possible typhoid fever with recent travel to a typhoid endemic area who was primarily managed as a case of multisystem inflammatory syndrome in children (MIS-C). The patient was initially treated for tonsillitis after a 3 day history of persistent fever, sore throat, and constipation. The patient presented later when he deteriorated. Severe acute respiratory syndrome coronavirus (SARS-CoV-2) viral RNA was not detected but the antibodies were positive. The patient went on to develop mucosal, cardiac, and gastrointestinal manifestations and was subsequently treated with immunoglobulins and corticosteroids for MIS-C. Despite the rarity of MIS-C as a complication of COVID-19 infection, the endemic typhoid fever which is relatively more common was not ruled out. The patient additionally received antibiotics for a total of 5 weeks given his unremitting fever. Even during the COVID-19 pandemic, healthcare professionals should carry out timely testing to exclude more probable differential diagnoses, with area-specific common diseases given due diligence.

The Burden of Typhoid Fever in Sub-Saharan Africa: A Perspective

While typhoid fever has largely been eliminated in high-income regions which have developed modern water, sanitation, and hygiene facilities, it remains a significant public health burden resulting in morbidity and mortality among millions of individuals in resource-constrained settings. Prevention and control efforts are needed that integrate several high-impact interventions targeting facilities and infrastructure, including those addressing improvements in sanitation, access to safe water, and planned urbanization, together with parallel efforts directed at effective strategies for use of typhoid conjugate vaccines (TCV). The use of TCVs is a critical tool with the potential of having a rapid impact on typhoid fever disease burden; their introduction will also serve as an important strategy to combat evolving antimicrobial resistance to currently available typhoid fever treatments. Well-designed epidemiological surveillance studies play a critical role in establishing the need for, and monitoring the impact of, typhoid fever control and prevention strategies implemented by public health authorities. Here, we present a perspective based on a narrative review of the impact of typhoid fever on morbidity and mortality in sub-Saharan Africa and discuss ongoing surveillance activities and the role of vaccination in prevention and control efforts.

British Infection Association Guidelines for the Diagnosis and Management of Enteric Fever in England

Enteric fever (EF) is an infection caused by the bacteria called Salmonella Typhi or Paratyphi. Infection is acquired through swallowing contaminated food or water. Most EF in England occurs in people returning from South Asia and other places where EF is common; catching EF in England is rare. The main symptom is fever, but stomach pain, diarrhoea, muscle aches, rash and other symptoms may occur. EF is diagnosed by culturing the bacteria from blood and/or stool in a microbiology laboratory. EF usually responds well to antibiotic treatment. Depending on how unwell the individual is, antibiotics may be administered by mouth or by injection. Over the past several years, there has been an overall increase in resistance to antibiotics used to treat enteric fever, in all endemic areas. Additionally, since 2016, there has been an ongoing outbreak of drug-resistant EF in Pakistan. This infection is called extensively drug-resistant, or XDR, EF and only responds to a limited number of antibiotics. Occasionally individuals develop complications of EF including confusion, bleeding, a hole in the gut or an infection of the bones or elsewhere. Some people may continue to carry the bacteria in their stool for a longtime following treatment for the initial illness. These people may need treatment with a longer course of antibiotics to eradicate infection. Travellers can reduce their risk of acquiring EF by following safe food and water practices and by receiving the vaccine at least a few weeks before travel. These guidelines aim to help doctors do the correct tests and treat patients for enteric fever in England but may also be useful to doctors and public health professionals in other similar countries.

An evaluation of kidney dysfunction as a common symptom of typhoid infection in an endemic country: A rare case study

Nephrotic syndrome and encephalopathy are uncommon complications that occurred in typhoid fever. The diagnosis is based on proteinuria finding with nephrotic range value, edema, and hypoalbuminemia. In this study, a 10-year-old boy was diagnosed with encephalopathy typhoid and nephrotic syndrome. The physical examination and urinalysis were conducted with methylprednisolone 60 mg/body surface area and captopril to reduce proteinuria.

Extensively Drug-Resistant Typhoid Fever in the United States

Cases of extensively drug-resistant (XDR) typhoid fever have been reported in the United States among patients who did not travel internationally. Clinicians should consider if and where the patient traveled when selecting empiric treatment for typhoid fever. XDR typhoid fever should be treated with a carbapenem, azithromycin, or both.

Typhoid in India: An Age-old Problem With an Existing Solution

Enteric fever continues to impact millions of people who lack adequate access to clean water and sanitation. The typhoid and paratyphoid fever burden in South Asia is broadly acknowledged, but current estimates of incidence, severity, and cost of illness from India are lacking. This supplement addresses this gap in our knowledge, presenting findings from two years of surveillance, conducted at multiple sites between October 2017 and February 2020, in the Surveillance for Enteric Fever in India (SEFI) network. Results provide contemporaneous evidence of high disease burden and cost of illness-the latter borne largely by patients in the absence of universal healthcare coverage in India. Against a backdrop of immediate priorities in the COVID-19 pandemic, these data are a reminder that typhoid, though often forgotten, remains a public health problem in India. Typhoid conjugate vaccines, produced by multiple Indian manufacturers, and recommended for use in high burden settings, ensure that the tools to tackle typhoid are an immediately available solution to this public health problem.

Vaccination in pregnancy - The when, what and how?

Immunization is a fundamental component of preventive healthcare. This gain special significance in pregnancy. Maternal antigen-specific IgG, is actively transported across the placenta during pregnancy. This significantly, contributes to infant immunity in the first few months of life. Vaccination during pregnancy has the potential to indirectly protect the most vulnerable infants during the first few months of life, when vaccine responses are generally poor and it is difficult to achieve rapid protection through immunization. This is especially relevant when there is prior exposure to infection in woman or vaccine administration. A vaccine given during pregnancy in these women would result in a booster response and a relatively high level of IgG protecting their children in initial few months of life. Passive antibody transfer from mother to fetus can protect fetuses from infection until their own immunization schedule is initiated. Lack of administration of appropriate vaccination to women during pregnancy lead to an increase in maternal and fetal morbidity and mortality from preventable infections like influenza, pertussis. Various preventable infections can lead to intensive care unit admission for mothers, preterm birth, and low birth weight babies. Recent covid pandemic has brought issue of vaccine use in pregnancy at forefront of all expectant mothers. Immunization with inactivated virus, bacterial vaccine and toxoids showed no evidence of adverse fetal effects. As a rule, live attenuated vaccines are not recommended in pregnancy. This paper gives snapshot of all vaccines, which can be used in pregnancy along with brief details regards various bacterial and viral infections , their common clinical features and effects on pregnancy outcome as well as fetus. This is will provide a useful guide for healthcare providers.

Association of Antibody-Dependent Neutrophil Phagocytosis With Distinct Antibody Glycosylation Profiles Following Typhoid Vaccination

Typhoid Vi-conjugate vaccines (Vi-TCV) have been developed to control typhoid fever in children in endemic regions. Previously, in a human challenge model of typhoid, Vi-TCV was administered prior to deliberate ingestion of Salmonella Typhi by healthy adult volunteers in the UK. Vi-specific antibody-dependent neutrophil phagocytosis (ADNP) was associated with protection against enteric fever in this model, but it is not known if ADNP is induced by vaccination of children. We measured ADNP in a cohort of Nepalese children receiving a Vi-TCV in a field study to investigate whether functional antibody responses were also present in children in an endemic setting. Furthermore, we investigated relationships between the functional antibody measures and other properties of the antibody response, including Vi-IgG and IgA titres, and Fc region glycosylation. Antibody-dependent neutrophil phagocytosis significantly increased in children aged 9 months to 15 years between the day of vaccination and 28 days following administration of Vi-TCV (D28). The magnitude of ADNP was also comparable with the levels of ADNP induced by plasma from vaccinated UK adults. Neither IgG nor IgA antibody titres significantly correlated with ADNP scores at D28; however, increased vaccine-induced ADNP was associated with decreased levels of IgG1 sialylation. These data suggest that vaccination with Vi-TCV produces functional antibody responses in children, which associate with specific glycosylation patterns of the Fc region.

Typhoid conjugate vaccine in Africa and Asia: Status of clinical evaluation and vaccine introduction

The disease burden of typhoid fever remains high in endemic areas in Asia and Africa, especially in children. Recent clinical trials conducted by the Typhoid Vaccine Acceleration Consortium show typhoid conjugate vaccine (TCV) to be safe, immunogenic, and efficacious at preventing blood culture-confirmed typhoid fever in African and Asian children. Pakistan, Liberia, and Zimbabwe recently introduced TCV through campaigns and routine childhood immunizations, providing protection for this vulnerable population. It is essential to continue this momentum while simultaneously filling data gaps - including typhoid complications - to inform decision-making on TCV introduction. A multidisciplinary approach including surveillance, water, sanitation, and hygiene investments, and large-scale TCV introduction is needed to decrease the burden and mortality of typhoid fever.

Multiple introductions of multidrug-resistant typhoid associated with acute infection and asymptomatic carriage, Kenya

Background:

Understanding the dynamics of infection and carriage of typhoid in endemic settings is critical to finding solutions to prevention and control.

Methods:

In a 3-year case-control study, we investigated typhoid among children aged <16 years (4670 febrile cases and 8549 age matched controls) living in an informal settlement, Nairobi, Kenya.

Results:

148 S. Typhi isolates from cases and 95 from controls (stool culture) were identified; a carriage frequency of 1 %. Whole-genome sequencing showed 97% of cases and 88% of controls were genotype 4.3.1 (Haplotype 58), with the majority of each (76% and 88%) being multidrug-resistant strains in three sublineages of the H58 genotype (East Africa 1 (EA1), EA2, and EA3), with sequences from cases and carriers intermingled.

Conclusions:

The high rate of multidrug-resistant H58 S. Typhi, and the close phylogenetic relationships between cases and controls, provides evidence for the role of carriers as a reservoir for the community spread of typhoid in this setting.

Funding:

National Institutes of Health (R01AI099525); Wellcome Trust (106158/Z/14/Z); European Commission (TyphiNET No 845681); National Institute for Health Research (NIHR); Bill and Melinda Gates Foundation (OPP1175797).

Case Report: Typhoid Fever Complicated by Ileal Perforation in an Urban Slum of Dhaka, Bangladesh

Intestinal perforation is one of the most dangerous complications of typhoid fever and demands urgent hospitalization, diagnosis, and surgical management to reduce morbidity and prevent mortality. Here, we report a case of typhoidal intestinal perforation in a 19 year-old young man detected by passive surveillance during a cluster-randomized trial with Vi-tetanus toxoid conjugate vaccine (Typhoid Vaccine Acceleration Consortium: TyVAC) in an urban slum area in Mirpur, Dhaka, Bangladesh. The patient presented with a high-grade fever, lower abdominal pain, and vomiting and was admitted to a healthcare facility. Physical examination and preoperative investigations of the patient suggested a presumptive diagnosis of intestinal perforation, and the patient was transferred to a tertiary-level hospital for surgical management. A positive blood culture, intraoperative findings, and histopathology of an intestinal biopsy confirmed ileal perforation due to typhoid fever. This case report highlights the need for prompt diagnosis and appropriate pre- and postoperative management of patients who appear with the symptoms of typhoidal intestinal perforation. This report further demonstrates the importance of systematic surveillance and proper evaluation to determine the true incidence rate of typhoid fever and intestinal perforation in Bangladesh.