The Identification of Enteric Fever-Specific Antigens for Population-Based Serosurveillance.

BACKGROUND: Enteric fever, caused by Salmonella enterica serovars Typhi and Paratyphi A, is a major public health problem in low- and middle-income countries. Moderate sensitivity and scalability of current methods likely underestimate enteric fever burden. Determining the serological responses to organism-specific antigens may improve incidence measures. METHODS: Plasma samples were collected from blood culture-confirmed enteric fever patients, blood culture-negative febrile patients over the course of 3 months, and afebrile community controls. A panel of 17 Salmonella Typhi and Paratyphi A antigens was purified and used to determine antigen-specific antibody responses by indirect ELISAs. RESULTS: The antigen-specific longitudinal antibody responses were comparable between enteric fever patients, patients with blood culture-negative febrile controls, and afebrile community controls for most antigens. However, we found that IgG responses against STY1479 (YncE), STY1886 (CdtB), STY1498 (HlyE), and the serovar-specific O2 and O9 antigens were greatly elevated over a 3-month follow up period in S. Typhi/S. Paratyphi A patients compared to controls, suggesting seroconversion. CONCLUSIONS: We identified a set of antigens as good candidates to demonstrate enteric fever exposure. These targets can be used in combination to develop more sensitive and scalable approaches to enteric fever surveillance and generate invaluable epidemiological data for informing vaccine policies. CLINICAL TRIAL REGISTRATION: ISRCTN63006567.

Host transcriptional meta-signatures reveal diagnostic biomarkers for Plasmodium falciparum malaria.

BACKGROUND: Transcriptomics has been used to evaluate immune responses during malaria in diverse cohorts worldwide. However, the high heterogeneity of cohorts and poor generalization of transcriptional signatures reported in each study limit their potential clinical applications. METHODS: We compiled 28 public datasets containing 1,556 whole blood or peripheral blood mononuclear cells (PBMC) transcriptome samples. We estimated effect sizes with Hedges´ g and DerSimonian-Laird random effects model for meta-analyses of uncomplicated malaria. Random forest models identified gene signatures that discriminate malaria from bacterial infections or malaria severity. Parasitological, hematological, immunological, and metabolomics data were used for validation. RESULTS: We identified three gene signatures denominated the uncomplicated Malaria Meta-Signature (uMMS), which discriminates P. falciparum malaria from uninfected controls; the Malaria or Bacteria Signature (MoBS), that distinguishes malaria from sepsis and enteric fever; and the cerebral Malaria Meta-Signature (cMMS), which characterizes individuals with cerebral malaria. These signatures correlate with clinical hallmark features of malaria. Blood transcription modules (BTM) indicate immune regulation by glucocorticoids, whereas cell development and adhesion are associated with cerebral malaria. CONCLUSION: Transcriptional meta-signatures reflecting immune cell responses provide potential biomarkers for translational innovation and suggest critical roles for metabolic regulators of inflammation during malaria.

Epidemiology of non-travel enteric fever cases in England: insights from 10 years of surveillance.

OBJECTIVES: In non-endemic countries, surveillance of non-travel cases of enteric fever is important to identify carriers and reduce secondary transmission. We characterised these cases in England between 2012 and 2021 and assessed potential sources of infection to inform guidance revision. STUDY DESIGN: Retrospective case-case. METHODS: We identified enteric fever cases from the national surveillance dataset. Non-travel cases were defined as no travel to an endemic country or travel but onset of >60 days after return. Multivariable logistic regression was used to identify factors associated with non-travel cases. We reviewed the case records of cases with unknown source of infection. RESULTS: Compared to travel cases, non-travel cases (7%; 225/3075) were older (odds ratio [OR] = 1.02, 95% confidence interval [CI]: 1.02-1.04), asymptomatic (OR = 9.3: 95% CI: 4.3-20.3), and confirmed with Salmonella typhi infection (OR = 1.74, 95% CI: 1.26-2.4). Non-travel cases had lower odds of being of Indian (OR = 0.27, 95% CI: 0.16-0.45) or Pakistani ethnicity (OR = 0.34, 95% CI: 0.16-0.45) than White British. Surveillance questionnaires identified a possible infection source for 53%: case records review identified a further 23%: 33% secondary transmission, mostly household; 21% had overseas visitors, or travelling family; 12% were carriers (cases with enteric fever in the past), 12% travelled to endemic country outside of the 60-day window, and 22% had other possible sources. Case records differentiated between travel 60-90 days (5%) vs travel years prior to onset (7%), suggesting carrier status. CONCLUSION: Not all possible carriers were identified through the surveillance questionnaire. Therefore, we recommend additional questions to systematically capture travel history beyond 60 days to assist in classifying carrier status and to updating the source of infection.

Extensively drug-resistant Salmonella typhi Infection in Adults; Experience from A Tertiary Care Hospital.

Objectives: This study aimed to determine the epidemiology, clinical features, and complications of extensively drug-resistant Salmonella typhi (XDR S. typhi) infection in adults. Method: This cross-sectional study enrolled adults with culture-proven XDR S. typhi admitted to Hayatabad Medical Complex, Peshawar from 1st March to 10th September 2022. Their demographic characteristics, clinical features, treatment, and complications were recorded. Results: Out of 84 patients, 68 (80.9%) were male. The mean age of enrolled patients was 25.2 ± 11.3 years. The mean duration of fever at the time of admission was 13.6 ± 8.2 days, respectively. The most common symptom was loose stools (n=25, 29.8%). Most of the patients (n=69, 82.1%) had received empirical treatment before hospitalization. The majority of the patients (n=42, 50%) received meropenem and a combination of meropenem and azithromycin (n=35, 41.7%) during the study. The time to defervescence for both regimens was similar. Five patients (6%) developed complications of enteric fever. There was no mortality among the participants. Conclusions: Diarrhea was the most common associated clinical feature in XDR typhoid fever. Most of the patients received meropenem alone or in combination with azithromycin with a comparable time to defervescence. The majority of the patients recovered uneventfully and there was no mortality among the study participants.

Early transcriptional responses to human enteric fever challenge.

Enteric fever, caused by oral infection with typhoidal Salmonella serovars, presents as a non-specific febrile illness preceded by an incubation period of 5 days or more. The enteric fever human challenge model provides a unique opportunity to investigate the innate immune response during this incubation period, and how this response is altered by vaccination with the Vi polysaccharide or conjugate vaccine. We find that on the same day as ingestion of typhoidal Salmonella, there is already evidence of an immune response, with 199 genes upregulated in the peripheral blood transcriptome 12 hours post-challenge (false discovery rate <0.05). Gene sets relating to neutrophils, monocytes, and innate immunity were over-represented (false discovery rate <0.05). Estimating cell proportions from gene expression data suggested a possible increase in activated monocytes 12 hours post-challenge (P = 0.036, paired Wilcoxon signed-rank test). Furthermore, plasma TNF-α rose following exposure (P = 0.011, paired Wilcoxon signed-rank test). There were no significant differences in gene expression (false discovery rate <0.05) in the 12 hours response between those who did and did not subsequently develop clinical or blood culture confirmed enteric fever or between vaccination groups. Together, these results demonstrate early perturbation of the peripheral blood transcriptome after enteric fever challenge and provide initial insight into early mechanisms of protection.

Potential of a novel flagellin epitope as a broad-spectrum vaccine candidate against enteric fever.

Relentless emergence of antibiotic resistant Salmonella strains, coupled with the drawbacks associated with currently available vaccines against enteric fever, warrants an urgent need to look for new vaccine candidates. Out of the multiple virulence factors harbored by Salmonella, flagella are regarded as one of the most important targets of innate as well as adaptive immune response. Individual Salmonella serotypes alternate between expression of two different antigenic forms encoded by fliC and fljB genes, respectively thereby employing this as a strategy to escape the host immune response. In the present study, using various immunoinformatic approaches, a flagellin epitope, present in both antigenic forms of typhoidal Salmonellae has been targeted. Following B-cell epitope and B-cell derived T-cell epitope prediction and interaction studies with major histocompatibility complexes using molecular docking, a peptide epitope was selected. Further, it was screened for its presence in majority of typhoidal serovars along with other useful attributes, in silico. Thereafter, safety studies were performed with the synthesized peptide. Subsequently, immunization studies were carried out using S. Typhi as well as S. Paratyphi A induced murine peritonitis model. Active immunization with peptide-BSA conjugate resulted in 75% and 80% mice survival following lethal challenge with S. Typhi and S. Paratyphi A respectively, along with a significant IgG antibody titer, thereby highlighting its immunogenic potential. Reduced bacterial burden in vital organs along with improved histoarchitecture and cytokine levels further substantiated the protective efficacy of the proposed candidate. Passive immunization studies with the candidate verified the protective efficacy of the generated antibodies against lethal challenge of bacteria in mice. Given the endemic nature of enteric fever and the antigenic variability observed in Salmonella serotypes, present study highlights the importance of using a vaccine candidate, which, along with generating a strong immune response, also exhibits a broad coverage against both, S. Typhi as well as S. Paratyphi A strains.

Socioeconomic and ethnic inequalities in incidence and severity of enteric fever in England 2015-2019: analysis of a national enhanced surveillance system.

There is limited research on whether inequalities exist among individuals from different ethnicities and deprivation status among enteric fever cases. The aim of the study was to investigate the association between the enteric fever incidence rates, ethnicity and deprivation for enteric fever cases in England. Additionally, it was assessed if ethnicity and deprivation were associated with symptom severity, hospital admission and absence from school/work using logistic regression models. Incidence rates were higher in the two most deprived index of multiple deprivation quintiles and those of Pakistani ethnicity (9.89, 95% CI 9.08-10.75) followed by Indian (7.81, 95% CI 7.18-8.49) and Bangladeshi (5.68, 95% CI 4.74-6.76) groups: the incidence rate in the White group was 0.07 (95% CI 0.06-0.08). Individuals representing Pakistani (3.00, 95% CI 1.66-5.43), Indian (2.05, 95% CI 1.18-3.54) and Other/Other Asian (3.51, 95% CI 1.52-8.14) ethnicities had significantly higher odds of hospital admission than individuals representing White (British/Other) ethnicity, although all three groups had statistically significantly lower symptom severity scores. Our results show that there are significant ethnic and socioeconomic inequalities in enteric fever incidence that should inform prevention and treatment strategies. Targeted, community-specific public health interventions are needed to impact on overall burden.

Ceftriaxone resistant Salmonella enterica serovar Paratyphi A identified in a case of enteric fever: first case report from Pakistan.

BACKGROUND: Enteric fever is an acute systemic infectious disease associated with substantial morbidity and mortality in low- and middle-income countries (LMIC), with a global burden of 14.3 million cases. Cases of enteric fever or paratyphoid fever, caused by Salmonella enterica serovar Paratyphi A (S. Para A) have been found to rise in many endemic and non-endemic countries. Drug resistance is relatively uncommon in S. Para A. Here we report a case of paratyphoid fever caused by ceftriaxone resistant S. Para A from Pakistan. CASE PRESENTATION: A 29-year-old female presented with a history of fever, headache, and shivering. Her blood culture revealed a S. Para A isolate (S7), which was resistant to ceftriaxone, cefixime, ampicillin and ciprofloxacin. She was prescribed oral Azithromycin for 10 days, which resulted in resolution of her symptoms. Two other isolates of S. Para A (S1 and S4), resistant to fluoroquinolone were also selected for comparison. DST and whole genome sequencing was performed for all three isolates. Sequence analysis was performed for identification of drug resistance and phylogeny. Whole Genome Sequencing (WGS) of S7 revealed the presence of plasmids, IncX4 and IncFIB(K). blaCTX-M-15 and qnrS1 genes were found on IncFIB(K). The gyrA S83F mutation conferring fluoroquinolone resistance was also found present. Multi-locus sequence typing (MLST) showed the S7 isolate to belong to ST129. S1 and S4 had the gyrA S83Y and S83F mutations respectively. CONCLUSIONS: We highlight the occurrence of plasmid-mediated ceftriaxone resistant strain of S. Para A. This is of significance as ceftriaxone is commonly used to treat paratyphoid fever and resistance in S. Para A is not known. Continuous epidemiological surveillance is required to monitor the transmission and spread of antimicrobial resistance (AMR) among Typhoidal Salmonellae. This will guide treatment options and preventive measures including the need for vaccination against S. Para A in the region.

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.

Seroincidence of Enteric Fever, Juba, South Sudan.

We applied a new serosurveillance tool to estimate typhoidal Salmonella burden using samples collected during 2020 from a population in Juba, South Sudan. By using dried blood spot testing, we found an enteric fever seroincidence rate of 30/100 person-years and cumulative incidence of 74% over a 4-year period.

Etiological spectrum of persistent fever in the tropics and predictors of ubiquitous infections: a prospective four-country study with pooled analysis.

BACKGROUND: Persistent fever, defined as fever lasting for 7 days or more at first medical evaluation, has been hardly investigated as a separate clinical entity in the tropics. This study aimed at exploring the frequencies and diagnostic predictors of the ubiquitous priority (i.e., severe and treatable) infections causing persistent fever in the tropics. METHODS: In six different health settings across four countries in Africa and Asia (Sudan, Democratic Republic of Congo [DRC], Nepal, and Cambodia), consecutive patients aged 5 years or older with persistent fever were prospectively recruited from January 2013 to October 2014. Participants underwent a reference diagnostic workup targeting a pre-established list of 12 epidemiologically relevant priority infections (i.e., malaria, tuberculosis, HIV, enteric fever, leptospirosis, rickettsiosis, brucellosis, melioidosis, relapsing fever, visceral leishmaniasis, human African trypanosomiasis, amebic liver abscess). The likelihood ratios (LRs) of clinical and basic laboratory features were determined by pooling all cases of each identified ubiquitous infection (i.e., found in all countries). In addition, we assessed the diagnostic accuracy of five antibody-based rapid diagnostic tests (RDTs): Typhidot Rapid IgM, Test-itTM Typhoid IgM Lateral Flow Assay, and SD Bioline Salmonella typhi IgG/IgM for Salmonella Typhi infection, and Test-itTM Leptospira IgM Lateral Flow Assay and SD Bioline Leptospira IgG/IgM for leptospirosis. RESULTS: A total of 1922 patients (median age: 35 years; female: 51%) were enrolled (Sudan, n = 667; DRC, n = 300; Nepal, n = 577; Cambodia, n = 378). Ubiquitous priority infections were diagnosed in 452 (23.5%) participants and included malaria 8.0% (n = 154), tuberculosis 6.7% (n = 129), leptospirosis 4.0% (n = 77), rickettsiosis 2.3% (n = 44), enteric fever 1.8% (n = 34), and new HIV diagnosis 0.7% (n = 14). The other priority infections were limited to one or two countries. The only features with a positive LR ≥ 3 were diarrhea for enteric fever and elevated alanine aminotransferase level for enteric fever and rickettsiosis. Sensitivities ranged from 29 to 67% for the three RDTs targeting S. Typhi and were 9% and 16% for the two RDTs targeting leptospirosis. Specificities ranged from 86 to 99% for S. Typhi detecting RDTs and were 96% and 97% for leptospirosis RDTs. CONCLUSIONS: Leptospirosis, rickettsiosis, and enteric fever accounted each for a substantial proportion of the persistent fever caseload across all tropical areas, in addition to malaria, tuberculosis, and HIV. Very few discriminative features were however identified, and RDTs for leptospirosis and Salmonella Typhi infection performed poorly. Improved field diagnostics are urgently needed for these challenging infections. TRIAL REGISTRATION: NCT01766830 at ClinicalTrials.gov.

gyrA ser83 mutation among fluoroquinolone-resistant Salmonella enterica serovars from enteric fever patients in tertiary care hospital, Kathmandu.

BACKGROUND: The management of enteric fever through antibiotics is difficult these days due to the emerging resistance of Salmonella to various antimicrobial agents. The development of antimicrobial resistance is associated with multiple factors including mutations in the specific genes. To know the current status of mutation-mediated fluoroquinolone-resistance among Salmonella enterica serovars; Typhi, Paratyphi A, B and C, this study was focused on detecting gyrA ser83 mutation by restriction digestion analysis of gyrA gene using HinfI endonuclease. RESULTS: A total of 948 blood samples were processed for isolation of Salmonella spp. and 3.4% of them were found to be positive for Salmonella growth. Out of the 32 Salmonella isolates, 2.2% were S. Typhi and 1.2% were S. Paratyphi A. More interestingly, we observed less than 5% of isolates were resistant to first-line drugs including chloramphenicol, cotrimoxazole and ampicillin. More than 80% of isolates were resistant to fluoroquinolones accounting for 84.4% to levofloxacin followed by 87.5% to ofloxacin and 100% to ciprofloxacin by disc diffusion methods. However, the minimum inhibitory concentration method using agar dilution showed only 50% of isolates were resistant to ciprofloxacin. A total of 3.1% of isolates were multidrug-resistant. Similarly, 90.6% of the Salmonella isolates showed gyrA ser83 mutation with resistance to nalidixic acid. CONCLUSIONS: The increased resistance to fluoroquinolones and nalidixic acid in Salmonella isolates in our study suggests the use of alternative drugs as empirical treatment. Rather, the treatment should focus on prescribing first-line antibiotics since we observed less than 5% of Salmonella isolates were resistant to these drugs.

Very long O-antigen chains of Salmonella Paratyphi A inhibit inflammasome activation and pyroptotic cell death.

Salmonella Paratyphi A (SPtA) remains one of the leading causes of enteric (typhoid) fever. Yet, despite the recent increased rate of isolation from patients in Asia, our understanding of its pathogenesis is incomplete. Here we investigated inflammasome activation in human macrophages infected with SPtA. We found that SPtA induces GSDMD-mediated pyroptosis via activation of caspase-1, caspase-4 and caspase-8. Although we observed no cell death in the absence of a functional Salmonella pathogenicity island-1 (SPI-1) injectisome, HilA-mediated overexpression of the SPI-1 regulon enhances pyroptosis. SPtA expresses FepE, an LPS O-antigen length regulator, which induces the production of very long O-antigen chains. Using a ΔfepE mutant we established that the very long O-antigen chains interfere with bacterial interactions with epithelial cells and impair inflammasome-mediated macrophage cell death. Salmonella Typhimurium (STm) serovar has a lower FepE expression than SPtA, and triggers higher pyroptosis, conversely, increasing FepE expression in STm reduced pyroptosis. These results suggest that differential expression of FepE results in serovar-specific inflammasome modulation, which mirrors the pro- and anti-inflammatory strategies employed by STm and SPtA, respectively. Our studies point towards distinct mechanisms of virulence of SPtA, whereby it attenuates inflammasome-mediated detection through the elaboration of very long LPS O-polysaccharides.

Antibiotyping and genotyping of extensively drug-resistant (XDR) Salmonella sp. isolated from clinical samples of Lahore, Pakistan.

AIMS: Antibiotic resistance is a major problem in Salmonella enterica serovar Typhi. The objective of this study was to evaluate the prevalence of XDR Salmonella among local population of Lahore and genotyping of isolates for antibiotic-resistant genes. METHODS AND RESULTS: A total of 200 blood samples from suspected typhoid fever patients were collected. One hundred and fifty-seven bacterial samples were confirmed as Salmonella Typhi and 23 samples were confirmed as Salmonella Paratyphi after biochemical, serological and PCR based molecular characterization. Antibiogram analysis classified 121 (67·2%) Salmonella isolates as MDR and 62 isolates (34·4%) as XDR. The predominant resistance gene was ampC with 47·7% prevalence, followed by gyrA, catA1, tet(A), aac (3)-la, qnrS, blaNDM-1 and blaCTX-M-15 genes in 45·5, 40, 21·6, 18·3, 11·6, 2·2 and 0·5% isolates respectively. Sequence analysis showed the presence of sul1 and dfrA7 gene cassette arrays in 12 class 1 integron integrase positive isolates. CONCLUSION: Large number of clinical XDR S. Typhi-resistant against third generation cephalosporins have been reported. SIGNIFICANCE AND IMPACT OF THE STUDY: The current study highlights the possible emergence of clinical XDR S. Typhi cases in Lahore, Pakistan. Potential attribution of phenotypic and genotypic XDR cases may help to contribute targeted therapy.

Evidence of hepatitis B infection and co-infection with enteric fever among febrile patients in a primary health facility in Kogi State, Nigeria.

Hepatitis B and enteric fever remain infectious diseases of major health concern and the etiologic agents share overlapping regions of high endemicity worldwide. This study determined the seroprevalence of hepatitis B and enteric fever among febrile patients in Ejule metropolis, North-central Nigeria. In a cross-sectional study, blood samples obtained from 200 consenting patients were screened for hepatitis B and enteric fever with standard diagnostics ABON hepatitis B surface antigen (HBsAg) and Widal agglutination tests, respectively. A structured questionnaire was used to collect socio-demographic and risk factor information. Of the 200 sera tested, 20 (10%) had HBV alone, 35 (17.5%) enteric fever while 6 (3%) had both HBV/enteric fever. Males recorded more HBV (12% vs 6.7%), enteric fever (20% vs 13.3%), and co-infection (3.2% vs 2.7%) than their counterpart females. Ages 18-30 years were more predisposed to single and dual infections compared to older categories. Although sex, ages as well as the participants' occupation were not significantly linked to both infections (p > .05). The prevalence of enteric fever differed significantly with being married (p = .01). The illiterate had a higher prevalence of HBV, enteric fever, and dual infection (16.7%, 25%, and 8.3%) compared to higher educational levels. The study confirms the endemicity of hepatitis B and enteric fever in the area. Their concurrent rate highlights the need for clinicians to always consider the laboratory diagnosis of both diseases among febrile patients in endemic regions for proper management in events of co-morbidity. The high prevalence of both infections in connection with illiteracy shows the need to further intensify education of masses on the predisposing risk factors.

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.

Typhoid Conjugate Vaccine: An Urgent Tool to Combat Typhoid and Tackle Antimicrobial Resistance.

Typhoid is endemic in many countries in South Asia and sub-Saharan Africa. The high burden of this age-old, preventable disease exacerbates constraints on the health systems of these countries. Currently, most patients are treated effectively in the community or outpatient departments, but with rising antimicrobial resistance and the dearth of novel antimicrobials in the horizon, we risk losing our primary defense against typhoid. Extensively drug-resistant Salmonella Typhi is spreading, and azithromycin is the last oral drug to continue treating typhoid in the community. With increasing azithromycin resistance, emergence of pan-oral drug resistant Salmonella Typhi is imminent. The high burden of typhoid is also an underlying cause of the unnecessary use of antimicrobials. In addition to implementing water sanitation and hygiene interventions to prevent typhoid, it is imperative to rapidly roll out typhoid conjugate vaccines in endemic countries. This will not only reduce the burden of typhoid but will also help interrupt the trend of increasing antimicrobial resistance.

Water, Sanitation, and Hygiene Practices in Urban Slums of Eastern India.

BACKGROUND: The Sustainable Development Goals identified universal access to water and sanitation facilities as key components for improving health. We assessed water, sanitation, and hygiene (WASH) practices and associated determinants among residents of urban slums in Kolkata, India. METHODS: Information on WASH practices was collected in 2 surveys (2018 and 2019) from participants of a prospective enteric fever surveillance conducted in 2 municipal wards of Kolkata. A composite WASH practice score was computed and a hierarchical stepwise multiple linear regression model constructed to identify key determinants of improved WASH score. RESULTS: Over 90% of households had access to piped water; 6% reported access to continuous supply. Adult women (61% in 2018; 45% in 2019) spent 20 minutes daily to fetch water. Access to improved latrines was almost universal, although 80% used shared facilities. Unhealthy disposal of children's stools was reported in both rounds. Food hygiene practices were high, with most (>90%) washing uncooked items before eating; frequent consumption of street food items was reported. CONCLUSIONS: The study area reported high WASH coverage. Unhygienic behavioral patterns predisposing to food- or water-borne diseases were also noted. Awareness building and sustainable community mobilization for food hygiene needs to be emphasized to ensure community well-being.

Factors Predicting Blood Culture Positivity in Children With Enteric Fever.

BACKGROUND: Blood culture, despite low sensitivity, is the gold standard for enteric fever diagnosis. Understanding predictors of blood culture positivity may help design strategies to optimize enteric fever diagnosis. METHODS: A cohort of 6760 children aged 0.5-15 years was followed for 3 years for enteric fever with blood cultures in an automated system, for fevers >3 days. Factors affecting test positivity in fevers and participant-level predictors for culture refusals were analyzed using regression models. RESULTS: Overall, 6097 suspected typhoid/paratyphoid fever (STF) episodes were reported, of which 5703 (93.5%) STFs had sampling for blood cultures, with 394 (6.5%) refusals. Salmonella enterica serovar Typhi/Paratyphi positivity was culture-confirmed in 3.8% (218/5703) of STF episodes. Older children (odds ratio [OR], 1.96 [95% CI, 1.39-2.77]), larger blood volume inoculated (OR, 2.82 [95% CI, 1.71-4.66]), higher temperatures during fever (OR, 3.77 [95% CI, 2.89-4.91]), and fevers diagnosed as suspected typhoid or acute undifferentiated fever (OR, 6.06 [95% CI, 3.11-11.78]) had a higher probability of culture positivity. Antibiotics before culture did not decrease culture positivity. Blood culture refusals were higher for children from wealthier households or with milder illness. CONCLUSIONS: Performing blood cultures in older children with fever, especially those fevers with toxic presentation and increasing blood volume for inoculation are strategies to improve enteric fever detection in surveillance settings.

Incidence of Enteric Fever in a Pediatric Cohort in North India: Comparison with Estimates from 20 Years Earlier.

BACKGROUND: An earlier cohort in 1995-1996 showed a very high burden of typhoid in Delhi. Our aim was to estimate the current overall and age-specific incidence of culture-confirmed enteric fever among children aged 6 months to 15 years in Delhi. METHODS: We enrolled a cohort of 6000 children aged 6 months to <14 years in South Delhi and followed them up weekly for 24 months or until 15 completed years of child age, whichever was earlier. Blood culture to confirm enteric fever was done in children with ≥3 consecutive days of fever. RESULTS: We recorded a total of 14 650 episodes of fever in the 11 510 person-years (PY) of follow-up. A total of 81 fever episodes were positive for enteric fever. The incidence (95% confidence interval) of all enteric fever was 703.7 (560.5-874.7) per 100 000 PY. The incidences of typhoid and paratyphoid fevers were 608.1 (95% confidence interval, 481.1-768.7) and 111.7 (59.5-191.1) per 100 000 PY, respectively, highest among children aged 10-15 years. CONCLUSIONS: Despite a 35% reduction in incidence compared with the 1995-1996 cohort, our study suggested a substantial burden of enteric fever in the population. Continued efforts to improve water, sanitation, and hygiene parameters along with implementation of novel vaccination strategies and disease surveillance can help achieve the goal of disease elimination.