Neurologic manifestations associated with an outbreak of typhoid fever, Malawi--Mozambique, 2009: an epidemiologic investigation

A case of typhoid fever with neurological presentation

Introduction

Typhoid fever, leading to systemic disease due to Salmonella enterica serotype Typhi, typically has gastrointestinal manifestation, however, neurologic complications-although uncommon, can arise. Aseptic meningitis and optic neuritis are rare manifestations that can be challenging to diagnose.

Case summary

Our patient a 31-year male presented with fever for 18 days associated with headache, rash, vomiting, diarrhea and progressive neurological symptoms in form of disorientation and blurred vision. On examination there was bilateral sixth cranial nerve palsy. Investigations were positive for typhoid fever with aseptic meningitis and optic neuritis. He was successfully treated with intravenous ceftriaxone and corticosteroids.

Conclusion

Atypical neurological symptoms of typhoid fever must be recognized. To prevent complications, early diagnosis and treatment are important. Typhoid fever should be considered in febrile patients with unexplainable neurological symptoms, especially in an endemic region.

Overview of management of infection-related movement disorders with focus on specific-infections

Infections are important treatable causes of secondary movement disorders (MD) that can have heterogeneous presentations. According to various studies, infection-related movement disorders (IRMD) account for around 10-20% of secondary MD. Certain infections have a predilection for causing various MD, and some MD phenomenologies, such as acute cerebellar ataxia and opsoclonus-myoclonus-ataxia syndromes (OMAS), suggest a strong possibility of an underlying infectious cause. The underlying pathophysiology is multifaceted, including direct neuronal damage due to neurotropism, granulomas, abscesses causing structural damage, and inflammatory and autoimmune responses triggered by infections. Understanding the prevalence, spectrum, and pattern of these IRMD and common infections that are responsible helps in early diagnosis, and instituting appropriate, timely treatment, thereby improving the overall prognosis and avoiding unnecessary investigations. In this review, we aim to provide a brief overview of common infections associated with MD, common clinical presentations of IRMD, their underlying pathophysiology, and overall approach to their treatment, with a focus on specific treatments of prevalent and treatable IRMD.

A Critical Review of the Neuropharmacological Effects of Kratom: An Insight from the Functional Array of Identified Natural Compounds

Kratom (Mitragyna speciosa Korth. Havil) has been considered a narcotic drug for years, barred by the law in many parts of the world, while extensive research over the past few decades proves its several beneficial effects, some of which are still in ambiguity. In many countries, including Thailand, the indiscriminate use and abuse of kratom have led to the loss of life. Nonetheless, researchers have isolated almost fifty pure compounds from kratom, most of which are alkaloids. The most prevalent compounds, mitragynine and 7-hydroxy mitragynine, are reported to display agonist morphine-like effects on human μ-opioid receptors and antagonists at κ- and δ-opioid receptors with multimodal effects at other central receptors. Mitragynine is also credited to be one of the modulatory molecules for the Keap1-Nrf2 pathway and SOD, CAT, GST, and associated genes' upregulatory cascades, leading it to play a pivotal role in neuroprotective actions while evidently causing neuronal disorders at high doses. Additionally, its anti-inflammatory, antioxidative, antibacterial, and gastroprotective effects are well-cited. In this context, this review focuses on the research gap to resolve ambiguities about the neuronal effects of kratom and demonstrate its prospects as a therapeutic target for neurological disorders associated with other pharmacological effects.

From Eberthella typhi to Salmonella Typhi: The Fascinating Journey of the Virulence and Pathogenicity of Salmonella Typhi

Salmonella Typhi (S. Typhi), the invasive typhoidal serovar of Salmonella enterica that causes typhoid fever in humans, is a severe threat to global health. It is one of the major causes of high morbidity and mortality in developing countries. According to recent WHO estimates, approximately 11-21 million typhoid fever illnesses occur annually worldwide, accounting for 0.12-0.16 million deaths. Salmonella infection can spread to healthy individuals by the consumption of contaminated food and water. Typhoid fever in humans sometimes is accompanied by several other critical extraintestinal complications related to the central nervous system, cardiovascular system, pulmonary system, and hepatobiliary system. Salmonella Pathogenicity Island-1 and Salmonella Pathogenicity Island-2 are the two genomic segments containing genes encoding virulent factors that regulate its invasion and systemic pathogenesis. This Review aims to shed light on a comparative analysis of the virulence and pathogenesis of the typhoidal and nontyphoidal serovars of S. enterica.

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.

Effect of novel therapeutic medicine swertiamarin from Enicostema axillare in zebrafish infected with Salmonella typhi

Herbal treatments have been practiced by humans over centuries and therefore possess time-proven safety. However, it is crucial to evaluate the toxic effects of herbal medicine to confirm their safety, particularly when developing therapeutic drugs. Use of laboratory animals such as mice, rat, and rabbits was considered as gold standard in herbal toxicity assessments. However, in the last few decades, the ethical consideration of using higher vertebrates for toxicity testing has become more controversial. As a possible alternative model involving lower vertebrates such as zebra fish were introduced. Hence in the present study, swertiamain compound isolated from E. axillare was assessed for it antimicrobial activity in zebra fish larvae againt S. typhi. The cumulative mortality rate and bacterial localization in zebra fish larvae were studied. Biochemical markers assays were performed to find the preventive role of the compound during the typhoid infection. The results showed that zebra fish can be successfully used as a model to study typhoid infection and the anti-bacterial compound swertiamarin used in this study clears the bacterial load and pathogenic symptoms to a great extent.

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.

Enteric fever presenting as catatonia syndrome - Case report

Enteric or typhoid fever is an emerging tropical infectious disease and a global public health problem with a documented spectrum of neuro-psychiatric manifestations especially from endemic countries. Although neuro-psychiatric manifestations are reported in nearly 50-75% of patients at any phase of enteric fever, the chance of their misdiagnosis and deferred diagnosis of the prime illness is quite common. Atypical symptoms are commonly attributed to be a part of 'typhoid toxaemia', the acute febrile phase of the illness. We report a case of young male presenting with catatonia in the aftermath of such.

Enteric Fever Diagnosis: Current Challenges and Future Directions

Enteric fever is a life-threatening systemic febrile disease caused by Salmonella enterica serovars Typhi and Paratyphi (S. Typhi and S. Paratyphi). Unfortunately, the burden of the disease remains high primarily due to the global spread of various drug-resistant Salmonella strains despite continuous advancement in the field. An accurate diagnosis is critical for effective control of the disease. However, enteric fever diagnosis based on clinical presentations is challenging due to overlapping symptoms with other febrile illnesses that are also prevalent in endemic areas. Current laboratory tests display suboptimal sensitivity and specificity, and no diagnostic methods are available for identifying asymptomatic carriers. Several research programs have employed systemic approaches to identify more specific biomarkers for early detection and asymptomatic carrier detection. This review discusses the pros and cons of currently available diagnostic tests for enteric fever, the advancement of research toward improved diagnostic tests, and the challenges of discovering new ideal biomarkers and tests.

A case of spastic quadriparesis secondary to enteric fever

Enteric fever is a systemic disease characterised predominantly by fever and abdominal pain, caused by dissemination of Salmonella Typhi or Salmonella Paratyphi. Enteric fever can affect many organ systems including liver, gastrointestinal tract, kidney and brain. Neurological manifestations occur in 2%-40% of patients and include meningitis, Gullian-Barré syndrome, neuritis and neuro-psychiatric symptoms. Spastic quadriparesis is a rare complication.

Acute sensorineural hearing loss as atypical presentation of typhoid fever in adult patient

Salmonella Typhi is the main cause of an acute febrile, sometimes fatal, multisystemic illness called typhoid fever. The diverse presentations of this disease make it a diagnostic challenge in some patients. Involvement of the neurological system, including cochleovestibular system, is very rare with less than a handful of reported cases. This case report describes the condition of a previously healthy 23-year-old Pakistani man with acute onset of hearing loss associated with fever, headache, and disorientation. The most likely differential diagnoses were bacterial or viral meningoencephalitis, and other bacterial infections, such as Rickettsial and spirochetal diseases. Salmonella Typhi grew on blood culture; thus, treatment with intravenous antibiotics and systemic steroids was provided with excellent response. Hearing loss gradually improved and almost completely resolved within 3 to 4 weeks.

Salmonella Typhoid Toxin PltB Subunit and Its Non-typhoidal Salmonella Ortholog Confer Differential Host Adaptation and Virulence

Typhoidal and non-typhoidal Salmonelleae (NTS) cause typhoid fever and gastroenteritis, respectively, in humans. Salmonella typhoid toxin contributes to typhoid disease progression and chronic infection, but little is known about the role of its NTS ortholog. We found that typhoid toxin and its NTS ortholog induce different clinical presentations. The PltB subunit of each toxin exhibits different glycan-binding preferences that correlate with glycan expression profiles of host cells targeted by each bacterium at the primary infection or intoxication sites. Through co-crystal structures of PltB subunits bound to specific glycan receptor moieties, we show that they induce markedly different glycan-binding preferences and virulence outcomes. Furthermore, immunization with the NTS S. Javiana or its toxin offers cross-reactive protection against lethal-dose typhoid toxin challenge. Cumulatively, these results offer insights into the evolution of host adaptations in Salmonella AB toxins, their cell and tissue tropisms, and the design for improved typhoid vaccines and therapeutics.

The role of 9-O-acetylated glycan receptor moieties in the typhoid toxin binding and intoxication

Typhoid toxin is an A2B5 toxin secreted from Salmonella Typhi-infected cells during human infection and is suggested to contribute to typhoid disease progression and the establishment of chronic infection. To deliver the enzymatic 'A' subunits of the toxin to the site of action in host cells, the receptor-binding 'B' subunit PltB binds to the trisaccharide glycan receptor moieties terminated in N-acetylneuraminic acid (Neu5Ac) that is α2-3 or α2-6 linked to the underlying disaccharide, galactose (Gal) and N-acetylglucosamine (GlcNAc). Neu5Ac is present in both unmodified and modified forms, with 9-O-acetylated Neu5Ac being the most common modification in humans. Here we show that host cells associated with typhoid toxin-mediated clinical signs express both unmodified and 9-O-acetylated glycan receptor moieties. We found that PltB binds to 9-O-acetylated α2-3 glycan receptor moieties with a markedly increased affinity, while the binding affinity to 9-O-acetylated α2-6 glycans is only slightly higher, as compared to the affinities of PltB to the unmodified counterparts, respectively. We also present X-ray co-crystal structures of PltB bound to related glycan moieties, which supports the different effects of 9-O-acetylated α2-3 and α2-6 glycan receptor moieties on the toxin binding. Lastly, we demonstrate that the cells exclusively expressing unmodified glycan receptor moieties are less susceptible to typhoid toxin than the cells expressing 9-O-acetylated counterparts, although typhoid toxin intoxicates both cells. These results reveal a fine-tuning mechanism of a bacterial toxin that exploits specific chemical modifications of its glycan receptor moieties for virulence and provide useful insights into the development of therapeutics against typhoid fever.

Outbreak of acute undifferentiated febrile illness in Kathmandu, Nepal: clinical and epidemiological investigation

Background

Outbreaks of acute undifferentiated febrile illness (AUFI) are common in Nepal, but the exact etiology or risk factors for them often go unrecognized. Diseases like influenza, enteric fever and rickettsial fevers account for majority of such outbreaks. Optimal diagnostic tests to inform treatment decisions are not available at the point-of-care. A proper epidemiological and clinical characterization of such outbreaks is important for appropriate treatment and control efforts.

Methods

An investigation was initiated as a response to increased presentation of patients at Patan Hospital from Chalnakhel locality in Dakchinkali municipality, Kathmandu with AUFI from June 10 to July 1, 2016. Focused group discussion with local inhabitants and the epidemiological curve of febrile patients at local primary health care centre confirmed the outbreak. The household-survey was conducted in the area with questionnaire administered on patients to characterize their illnesses and their medical records were reviewed. A different set of questionnaire was administered on the patients and controls to investigate the association with common risk factors. Water samples were collected and analyzed microbiologically.

Results

Eighty one patients from 137 households suffered from febrile illness within 6 weeks window before the investigation. All the 67 sampled patients with acute fever had a generalized illness without a discernible focus of infection. Only 38% of the patients had received a clinical diagnosis while the rest were treated empirically without a diagnosis. Three patients had blood culture confirmed enteric fever. Forty-two (63%) patients had been administered antibiotics, most commonly, ofloxacin, cefixime or azithromycin with a mean fever clearance time of 4 days. There was no definite association between several risk factors and fever. Fecal contamination was noted in tap water samples.

Conclusion

Based on the pattern of illness, this outbreak was most likely a mixture of self-limiting viral infections and enteric fever. This study shows that even in the absence of a confirmed diagnosis, a detailed characterization of the illness at presentation and the recovery course can suggest the diagnosis and help in formulating appropriate recommendation for treatment and control.

Ascertaining the burden of invasive Salmonella disease in hospitalised febrile children aged under four years in Blantyre, Malawi

Typhoid fever is endemic across sub-Saharan Africa. However, estimates of the burden of typhoid are undermined by insufficient blood volumes and lack of sensitivity of blood culture. Here, we aimed to address this limitation by exploiting pre-enrichment culture followed by PCR, alongside routine blood culture to improve typhoid case detection. We carried out a prospective diagnostic cohort study and enrolled children (aged 0-4 years) with non-specific febrile disease admitted to a tertiary hospital in Blantyre, Malawi from August 2014 to July 2016. Blood was collected for culture (BC) and real-time PCR after a pre-enrichment culture in tryptone soy broth and ox-bile. DNA was subjected to PCR for invA (Pan-Salmonella), staG (S. Typhi), and fliC (S. Typhimurium) genes. A positive PCR was defined as invA plus either staG or fliC (CT<29). IgM and IgG ELISA against four S. Typhi antigens was also performed. In total, 643 children (median age 1.3 years) with nonspecific febrile disease were enrolled; 31 (4.8%) were BC positive for Salmonella (n = 13 S. Typhi, n = 16 S. Typhimurium, and n = 2 S. Enteritidis). Pre-enrichment culture of blood followed by PCR identified a further 8 S. Typhi and 15 S. Typhimurium positive children. IgM and IgG titres to the S. Typhi antigen STY1498 (haemolysin) were significantly higher in children that were PCR positive but blood culture negative compared to febrile children with all other non-typhoid illnesses. The addition of pre-enrichment culture and PCR increased the case ascertainment of invasive Salmonella disease in children by 62-94%. These data support recent burden estimates that highlight the insensitivity of blood cultures and support the targeting of pre-school children for typhoid vaccine prevention in Africa. Blood culture with real-time PCR following pre-enrichment should be used to further refine estimates of vaccine effectiveness in typhoid vaccine trials.

Mild Encephalopathy/Encephalitis with Reversible Splenial Lesion in a Patient with Salmonella typhi Infection: An Unusual Presentation with Excellent Prognosis

Mild encephalopathy/encephalitis with reversible splenial lesion (MERS) is an uncommon clinicoradiological entity reported mainly in East Asian population. Mild encephalopathy/encephalitis with reversible splenial lesion is characterized by neuropsychiatric manifestations, magnetic resonance imaging (MRI) findings of the reversible lesions in the splenium of corpus callosum, and good clinical outcomes. These transient splenial lesions are not specific to a particular condition and have been described mainly in children in various situations including epilepsy or peri-ictal state, antiepileptic drug use, and infectious agents such as influenza virus, Mycoplasma pneumoniae, Legionella pneumophila, and O-157 Escherichia coli. Mild encephalopathy/encephalitis with reversible splenial lesion is an uncommon complication of Salmonella infection and has been described earlier in a child who made excellent clinical recovery. We report a case of Salmonella typhi encephalopathy in a young adult who presented with reversible transient splenial lesions on MRI. The patient recovered without neurological sequelae. Awareness of these lesions is important as these are uncommon findings on MRI and carry excellent prognosis.

How to cite this article

Chopra P, Bhatia RS, Chopra R. Mild Encephalopathy/Encephalitis with Reversible Splenial Lesion in a Patient with Salmonella typhi Infection: An Unusual Presentation with Excellent Prognosis. Indian J Crit Care Med 2019;23(12):584-586.

Why Is Eradicating Typhoid Fever So Challenging: Implications for Vaccine and Therapeutic Design

Salmonella enterica serovar Typhi (S. Typhi) and S. Paratyphi, namely typhoidal Salmonellae, are the cause of (para) typhoid fever, which is a devastating systemic infectious disease in humans. In addition, the spread of multidrug-resistant (MDR) and extensively drug-resistant (XDR) S. Typhi in many low and middle-income countries poses a significant risk to human health. While currently available typhoid vaccines and therapeutics are efficacious, they have some limitations. One important limitation is the lack of controlling individuals who chronically carry S. Typhi. However, due to the strict host specificity of S. Typhi to humans, S. Typhi research is hampered. As a result, our understanding of S. Typhi pathogenesis is incomplete, thereby delaying the development and improvement of prevention and treatment strategies. Nonetheless, to better combat and contain S. Typhi, it is vital to develop a vaccine and therapy for controlling both acutely and chronically infected individuals. This review discusses how scientists are trying to combat typhoid fever, why it is so challenging to do so, which approaches show promise, and what we know about the pathogenesis of S. Typhi chronic infection.

The Burden of Typhoid Fever in South Africa: The Potential Impact of Selected Interventions

Typhoid fever is notifiable in South Africa but clinical notification is notoriously poor. South Africa has an estimated annual incidence rate of 0.1 cases per 100,000 population of culture-confirmed typhoid fever, decreased from 17 cases per 100,000 population in the 1980s. This work was undertaken to identify the reasons for this decrease and identify potential weaknesses that may result in an increase of observed cases. Culture-confirmed cases, with additional demographic and clinical data have been collected from selected sentinel sites since 2003. Data on contextual factors (gross domestic product [GDP], sanitation, female education, and childhood diarrhea mortality) were collected. National incidence rates of culture-confirmed typhoid fever have remained constant for the past 13 years, with the exception of an outbreak in 2005: incidence was 0.4 per 100,000 population. Paratyphoid fever remains a rare disease. Antimicrobial susceptibility data suggest resistance to ciprofloxacin and azithromycin is emerging. The South African population increased from 27.5 million in 1980 to 55.0 million in 2015: urbanization increased from 50% to 65%, GDP increased from United States Dollar (USD) $2,910 to USD $6,167, access to sanitation improved from 64.4% to 70.0% in the urban population and 26.4% to 60.5% in rural areas. Female literacy levels improved from 74.8% to 92.6% over the period. Improved socioeconomic circumstances in South Africa have been temporally associated with decreasing incidence rates of typhoid fever over a 35-year period. Ongoing challenges remain including potential for large outbreaks, a large immigrant population, and emerging antimicrobial resistance. Continued active surveillance is mandatory.

In vivo tropism of Salmonella Typhi toxin to cells expressing a multiantennal glycan receptor

Typhoid fever is a life-threatening disease, but little is known about the molecular bases for its unique clinical presentation. Typhoid toxin, a unique virulence factor of Salmonella Typhi (the cause of typhoid fever), recapitulates in an animal model many symptoms of typhoid fever. Typhoid toxin binding to its glycan receptor Neu5Ac is central, but, due to the ubiquity of Neu5Ac, how typhoid toxin causes specific symptoms remains elusive. Here we show that typhoid toxin displays in vivo tropism to cells expressing multiantennal glycoprotein receptors, particularly on endothelial cells of arterioles in the brain and immune cells, which is in line with typhoid symptoms. Neu5Ac displayed by multiantennal N-glycans, rather than a single Neu5Ac, appears to serve as the high-affinity receptor, as typhoid toxin possesses five identical binding pockets per toxin. Human counterparts also express the multiantennal Neu5Ac receptor. Here we also show that mice immunized with inactive typhoid toxins and challenged with wild-type typhoid toxin presented neither the characteristic in vivo tropism nor symptoms. These mice were protected against a lethal-dose toxin challenge, but Ty21a-vaccinated mice were not. Cumulatively, these results reveal remarkable features describing how a bacterial exotoxin induces virulence exclusively in specific cells at the organismal level.

Encephalitis in a traveller with typhoid fever: efficacy of corticosteroids

Typhoid fever is a bacterial infection caused by Salmonella typhi or S. paratyphi, recognized as a classical cause of fever in returning travellers. However, neuropsychiatric presentations are rarely reported in travellers diagnosed in western countries, whereas they are more commonly described in patients treated in endemic areas. We describe such a case and discuss the pathophysiologic mechanisms of this complication.

The Role of Typhoid Toxin in Salmonella Typhi Virulence

Unlike many of the nontyphoidal Salmonella serovars such as S. Typhimurium that cause restricted gastroenteritis, Salmonella Typhi is unique in that it causes life-threatening typhoid fever in humans. Despite the vast difference in disease outcomes that S. Typhi and S. Typhimurium cause in humans, there are few genomic regions that are unique to S. Typhi. Of these regions, the most notable is the small locus encoding typhoid toxin, an AB toxin that has several distinct characteristics that contribute to S. Typhi's pathogenicity. As a result, typhoid toxin and its role in S. Typhi virulence have been studied in an effort to gain insight into potential treatment and prevention strategies. Given the rise of multidrug-resistant strains, research in this area has become increasingly important. This article discusses the current understanding of typhoid toxin and potential directions for future research endeavors in order to better understand the contribution of typhoid toxin to S. Typhi virulence.

The burden of typhoid fever in low- and middle-income countries: A meta-regression approach

Background

Upcoming vaccination efforts against typhoid fever require an assessment of the baseline burden of disease in countries at risk. There are no typhoid incidence data from most low- and middle-income countries (LMICs), so model-based estimates offer insights for decision-makers in the absence of readily available data.

Methods

We developed a mixed-effects model fit to data from 32 population-based studies of typhoid incidence in 22 locations in 14 countries. We tested the contribution of economic and environmental indices for predicting typhoid incidence using a stochastic search variable selection algorithm. We performed out-of-sample validation to assess the predictive performance of the model.

Results

We estimated that 17.8 million cases of typhoid fever occur each year in LMICs (95% credible interval: 6.9–48.4 million). Central Africa was predicted to experience the highest incidence of typhoid, followed by select countries in Central, South, and Southeast Asia. Incidence typically peaked in the 2–4 year old age group. Models incorporating widely available economic and environmental indicators were found to describe incidence better than null models.

Conclusions

Recent estimates of typhoid burden may under-estimate the number of cases and magnitude of uncertainty in typhoid incidence. Our analysis permits prediction of overall as well as age-specific incidence of typhoid fever in LMICs, and incorporates uncertainty around the model structure and estimates of the predictors. Future studies are needed to further validate and refine model predictions and better understand year-to-year variation in cases.

Typhoid fever is a bacterial enteric infection that continues to pose a considerable burden to the 5.5 billion people living in low- and middle-income countries (LMICs). We developed and validated a model incorporating widely available indicators of economic and social development and the environment to estimate the burden of typhoid fever across LMICs. Our analysis uses all available data to estimate the incidence of typhoid in key age groups, which is important for the design and implementation of optimal vaccination strategies, and it identifies regions of the world that have the most uncertainty in typhoid incidence. Across all LMICs, we estimated that the expected number of typhoid fever cases per year is 17.8 million (95% CI: 6.9–48.4 million). We also present the probability that incidence surpasses the criteria for low, medium, high, and very high incidence in each country, which could help guide policy in the face of uncertainty.

Rapid emergence of multidrug resistant, H58-lineage Salmonella typhi in Blantyre, Malawi

INTRODUCTION

Between 1998 and 2010, S. Typhi was an uncommon cause of bloodstream infection (BSI) in Blantyre, Malawi and it was usually susceptible to first-line antimicrobial therapy. In 2011 an increase in a multidrug resistant (MDR) strain was detected through routine bacteriological surveillance conducted at Queen Elizabeth Central Hospital (QECH).

METHODS

Longitudinal trends in culture-confirmed Typhoid admissions at QECH were described between 1998-2014. A retrospective review of patient cases notes was conducted, focusing on clinical presentation, prevalence of HIV and case-fatality. Isolates of S. Typhi were sequenced and the phylogeny of Typhoid in Blantyre was reconstructed and placed in a global context.

RESULTS

Between 1998-2010, there were a mean of 14 microbiological diagnoses of Typhoid/year at QECH, of which 6.8% were MDR. This increased to 67 in 2011 and 782 in 2014 at which time 97% were MDR. The disease predominantly affected children and young adults (median age 11 [IQR 6-21] in 2014). The prevalence of HIV in adult patients was 16.7% [8/48], similar to that of the general population (17.8%). Overall, the case fatality rate was 2.5% (3/94). Complications included anaemia, myocarditis, pneumonia and intestinal perforation. 112 isolates were sequenced and the phylogeny demonstrated the introduction and clonal expansion of the H58 lineage of S. Typhi.

CONCLUSIONS

Since 2011, there has been a rapid increase in the incidence of multidrug resistant, H58-lineage Typhoid in Blantyre. This is one of a number of reports of the re-emergence of Typhoid in Southern and Eastern Africa. There is an urgent need to understand the reservoirs and transmission of disease and how to arrest this regional increase.

Formative investigation of acceptability of typhoid vaccine during a typhoid fever outbreak in Neno District, Malawi

Typhoid fever affects an estimated 22 million people annually and causes 216,000 deaths worldwide. We conducted an investigation in August and September 2010 to examine the acceptability of typhoid vaccine in Neno District, Malawi where a typhoid outbreak was ongoing. We used qualitative methods, including freelisting exercises, key informant and in-depth interviews, and group discussions. Respondents associated illness with exposure to "bad wind," and transmission was believed to be airborne. Typhoid was considered extremely dangerous because of its rapid spread, the debilitating conditions it produced, the number of related fatalities, and the perception that it was highly contagious. Respondents were skeptical about the effectiveness of water, sanitation, and hygiene (WaSH) interventions. The perceived severity of typhoid and fear of exposure, uncertainty about the effectiveness of WaSH measures, and widespread belief in the efficacy of vaccines in preventing disease resulted in an overwhelming interest in receiving typhoid vaccine during an outbreak.

Catatonia and parkinsonism as a sequelae of typhoid fever: a rare experience

Although neurological manifestations of typhoid fever was thought to be obsolete from modern world, emergence of multidrug resistant typhoid bacilli and reporting of outbreak of typhoid fever with a range of early neuropsychiatric manifestations from various parts of world has led clinicians and investigators to re-evaluate the clinical spectrum of this endemic sinister disease. An 18-year-old male student was admitted in psychiatry ward with mutism, staring look, posturing and rigidity. There was history of typhoid fever 1 week before for which he was prescribed cefuroxime. Although investigations fail to provide any clue, his catatonic symptoms disappeared 2 weeks later giving way to resting tremor, bradykinesia, cog-wheel rigidity but without gait abnormality. He was successfully treated with lorazepam, amantidine, olanzapine and pramiprexole. The patient was asymptomatic within a month. He had no recurrence of symptoms till last follow-up, 6 months from the illness.

Vaccination for typhoid fever in sub-Saharan Africa

Emerging data on the epidemiologic, clinical and microbiologic aspects of typhoid fever in sub-Saharan Africa call for new strategies and new resources to bring the regional epidemic under control. Areas with endemic disease at rates approaching those in south Asia have been identified; large, prolonged and severe outbreaks are occurring more frequently; and resistance to antimicrobial agents, including fluoroquinolones is increasing. Surveillance for typhoid fever is hampered by the lack of laboratory resources for rapid diagnosis, culture confirmation and antimicrobial susceptibility testing. Nonetheless, in 2010, typhoid fever was estimated to cause 725 incident cases and 7 deaths per 100,000 person years in sub-Saharan Africa. Efforts for prevention and outbreak control are challenged by limited access to safe drinking water and sanitation and by a lack of resources to initiate typhoid immunization. A comprehensive approach to typhoid fever prevention including laboratory and epidemiologic capacity building, investments in water, sanitation and hygiene and reconsideration of the role of currently available vaccines could significantly reduce the disease burden. Targeted vaccination using currently available typhoid vaccines should be considered as a short- to intermediate-term risk reduction strategy for high-risk groups across sub-Saharan Africa.