Detection of Salmonella genes in stool samples of children aged 5 years and younger in urban and rural areas of Bangladesh.

INTRODUCTION: Typhoid incidence in children is higher in urban areas than in rural areas of Bangladesh. This study examined whether healthy urban children harboured higher levels of Salmonella genes than healthy rural children. METHODOLOGY: Stool samples from 140 children were studied: 70 from rural areas and 70 from urban metropolitan areas. RESULTS: The stool samples of urban children contained more Salmonella genes (median 4, IQR 3-4) than those of rural children (median 3, IQR 3-4). This suggests that urban Bangladeshi children have more Salmonella genes in their guts than rural children. Especially, in those under 12 months of age, the Salmonella gene prevalence in urban children was unique. They had more Salmonella genes (median 4, IQR 4-5) than rural children in the same age group (median 3, IQR 2.5-4). We also found more Salmonella genes in urban children who drank tap water (median 4, IQR 3-5) than in rural children whose water source was tube well water (median 3, IQR 2-4) and boiled pond water (median 3, IQR 3-3.5). However, there was no significant difference of Salmonella genes between urban children who drank tap-water and children whose water source was a tube well (median 4, IQR 3-4). CONCLUSIONS: These data suggest that the urban environment, including the drinking water supply system, increases the likelihood of healthy children in urban areas harbouring more potentially pathogenic Salmonella organisms in their gut than found in rural healthy children.

Clinical Perspectives of Multiple and Extensively Drug-Resistant Typhoid; result from a tertiary care hospital from Pakistan.

INTRODUCTION: Typhoid fever remains a problem in developing countries, including Pakistan. The emergence of multidrug-resistant and, since 2016, of extensively drug-resistant cases is a continuous challenge for health care workers. The COVID-19 pandemic is making management more difficult. METHODOLOGY: In the present study, a total of 52 confirmed cases of typhoid have been studied during 2019. Detailed clinical features, complications and, lab findings were studied. Typhoid culture and sensitivity were recorded and patients were treated accordingly. Patients were asked about risk factors to aim at informing prevention. RESULTS: Out of the 52 having blood culture positive for Salmonella Typhi 47 (90.4%) and Salmonella Paratyphi 5 (9.6%), 4 (7.7%) were sensitive to first-line (Non-resistant), 11 (21.2%) MDR and 37 (71.2%) patient were XDR. One case was resistant to azithromycin. Nausea, vomiting or, abdominal pain was present in 12 (23%), abdominal distension present in 9 (17.3%), abdominal tenderness in 8 (15.4%), hepatomegaly in 10 (19.2%) and, splenomegaly in 22 (42.3%).There were ultrasound abnormalities in 58% of patients and GI complications in 19% of patients. No significant difference was found in clinical findings and complications between resistant and non-resistant cases. Only 23-27% of patients were aware of typhoid prevention and vaccination measures. CONCLUSIONS: The increasing prevalence of resistance and higher degree of complications seen in typhoid fever raises the concern further about prevention and effective infection management in the community as well as clinical settings. Moreover, judicial use of antibiotics is much needed in developing countries like Pakistan.

Hyperexpression of type III secretion system of Salmonella Typhi linked to a higher cytotoxic effect to monocyte-derived macrophages by activating inflammasome.

Inflammasome activation is an important host response to infectious diseases, but the difference in inflammasome activation between typhoid fever and non-typhoidal Salmonella infection has been rarely studied. To determine whether inflammasome activation in macrophages after S. Typhi and S. Typhimurium infection is different, we measured pyroptosis, caspase-1 activation, and IL-1ß secretion in monocyte-derived macrophages infected with S. Typhi or S. Typhimurium both in vitro and ex vivo. The role of Vi capsule and virulence genes in Salmonella pathogenicity island-1 (SPI-1), belonging to type III secretion system, was also examined. S. Typhi caused more pyroptosis, caspase-1 activation, and IL-1ß production than S. Typhimurium did, predominantly within 2 h of infection, in the context of high number of infecting bacteria. Mutagenesis and complementation experiments confirmed that SPI-1 effectors but not Vi were associated with greater inflammasome activation. The expression levels of invA and hilA were significantly higher in S. Typhi than in S. Typhimurium at early log phase in SPI-1 environment. Thus, S. Typhi, relative to its non-typhoidal counterpart, S. Typhimurium, induces greater SPI-1-dependent inflammasome activation in monocyte-derived macrophages. This finding may explain why S. Typhi causes a hyperinflammatory state at bacteremic stage in 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.

Using hospital-based studies of community-onset bloodstream infections to make inferences about typhoid fever incidence.

OBJECTIVES: Hospital-based studies of community-onset bloodstream infections (CO-BSI) are less resource-intensive to carry out than population-based incidence studies. We examined several metrics capturing the potential role of Salmonella Typhi as a cause of CO-BSI for making inferences about incidence. METHODS: We systematically reviewed three databases for hospital-based studies of CO-BSI. We determined, by study, the prevalence and rank order of Salmonella among pathogenic bloodstream isolates, and the prevalence ratio of Salmonella Typhi to Escherichia coli (S:E ratio). We then describe these hospital-based study metrics in relation to population-based typhoid fever incidence data from a separate systematic review. RESULTS: Forty-four studies met the inclusion criteria, of which 23 (52.3%) isolated Salmonella Typhi at least once. Among studies isolating Salmonella Typhi, the median (interquartile range) prevalence and rank order of Salmonella Typhi compared to other pathogens isolated in BSI was 8.3% (3.2-37.9%) and 3 (1-6), respectively. The median (interquartile range) S:E ratio was 1.0 (0.4-3.0). With respect to incidence, in Pemba Island, Tanzania, prevalence, rank order, S:E ratio, and incidence was 64.8%, 1, 9.2 and 110 cases per 100 000, respectively, and in Boulkiemdé, Burkina Faso, was 13.3%, 3, 2.3 and 249 cases per 100 000. CONCLUSIONS: We describe considerable variation in place and time for Salmonella Typhi prevalence, rank order, and S:E ratio among hospital-based studies of CO-BSI. Data from simultaneous typhoid prevalence and incidence studies are limited. We propose that hospital-based study metrics warrant evaluation for making inference about typhoid incidence and as covariates in typhoid incidence models.

OBJECTIFS: Les études hospitalières d'infections d'origine sanguine acquises dans la communauté (IS-AC) consomment moins de ressources que les études d'incidence basées sur la population. Nous avons examiné plusieurs paramètres permettant de déterminer le rôle de Salmonella typhi comme cause des IS-AC pour permettre des déductions sur l'incidence. MÉTHODES: Nous avons systématiquement passé en revue trois bases de données sur des études hospitalières d'IS-AC. Par étude, nous avons déterminé la prévalence et l'ordre de classement de Salmonella parmi les isolats de pathogènes sanguins, ainsi que le rapport de prévalence de Salmonella typhi et Escherichia coli (rapport S:E). Nous décrivons ensuite ces résultats d'étude en milieu hospitalier en relation avec les données d'incidence de la fièvre typhoïde basées sur la population, tirées d'une revue systématique distincte. RÉSULTATS: Quarante-quatre études remplissaient les critères d'inclusion, dont 23 (52,3%) avaient isolé au moins une fois Salmonella typhi. Parmi les études isolant Salmonella typhi, la prévalence médiane (intervalle interquartile) et l'ordre de classement de Salmonella typhi par rapport aux autres agents pathogènes isolés de sangs étaient de 8,3% (3,2 à 37,9%) et de 3 (1-6), respectivement. Le rapport S:E médian (intervalle interquartile) était de 1,0 (0,4 à 3,0). En ce qui concerne l'incidence, sur l'île de Pemba, en Tanzanie, la prévalence, l'ordre de classement, le rapport S:E et l'incidence étaient respectivement de 64,8% ; 1 ; 9,2 et 110 cas pour 100.000, et dans le Boulkiemdé, au Burkina Faso, de 13,3% ; 3 ; 2,3 et 249 cas pour 100.000 habitants. CONCLUSIONS: Nous décrivons une variation considérable selon le lieu et le moment de la prévalence, de l'ordre de classement et du rapport S:E de Salmonella typhi parmi les études hospitalières sur les IS-AC. Les données provenant d'études simultanées sur la prévalence et l'incidence de la typhoïde sont limitées. Au vu des variations, nous proposons que les métriques d'étude en milieu hospitalier soient évaluées en tant que covariables dans les modèles de détermination de l'incidence de la typhoïde.

An unusual case of caecal perforation following ileostomy reversal.

A 63-year-old man with a history of gastro-oesophageal reflux disease underwent defunctioning loop ileostomy for obstructing metastatic rectal cancer prior to receiving long-course neoadjuvant chemoradiotherapy. Four months post completion of neoadjuvant therapy, he underwent an uncomplicated elective ultra-low anterior resection with formation of colonic J pouch and first stage liver metastasectomy for bilobar liver disease. At 1 year, he proceeded to an elective closure of loop ileostomy. Unfortunately, his postoperative course was complicated by profuse diarrhoea with subsequent colonic perforation, necessitating an emergency laparotomy and ileocolic resection with end ileostomy formation. Histopathology and stool studies were consistent with Salmonella Typhi infection. At the present time, Salmonella Typhi causing toxic megacolon and subsequent colonic perforation is an uncommon phenomenon in Australia. Here, we present an unusual case and explain why bowel perforation in this instance likely had a multifactorial aetiology.

Investigation of the role of typhoid toxin in acute typhoid fever in a human challenge model.

Salmonella Typhi is a human host-restricted pathogen that is responsible for typhoid fever in approximately 10.9 million people annually1. The typhoid toxin is postulated to have a central role in disease pathogenesis, the establishment of chronic infection and human host restriction2-6. However, its precise role in typhoid disease in humans is not fully defined. We studied the role of typhoid toxin in acute infection using a randomized, double-blind S. Typhi human challenge model7. Forty healthy volunteers were randomized (1:1) to oral challenge with 104 colony-forming units of wild-type or an isogenic typhoid toxin deletion mutant (TN) of S. Typhi. We observed no significant difference in the rate of typhoid infection (fever ≥38 °C for ≥12 h and/or S. Typhi bacteremia) between participants challenged with wild-type or TN S. Typhi (15 out of 21 (71%) versus 15 out of 19 (79%); P = 0.58). The duration of bacteremia was significantly longer in participants challenged with the TN strain compared with wild-type (47.6 hours (28.9-97.0) versus 30.3(3.6-49.4); P ≤ 0.001). The clinical syndrome was otherwise indistinguishable between wild-type and TN groups. These data suggest that the typhoid toxin is not required for infection and the development of early typhoid fever symptoms within the context of a human challenge model. Further clinical data are required to assess the role of typhoid toxin in severe disease or the establishment of bacterial carriage.

Investigation of a typhoid fever epidemic in Moyale Sub-County, Kenya, 2014-2015.

AIM: Typhoid fever is a vaccine-preventable bacterial disease that causes significant morbidity and mortality throughout Africa. This paper describes an upsurge of typhoid fever cases in Moyale Sub-County (MSC), Kenya, 2014-2015. METHODS: We conducted active hospital and health facility surveillance and laboratory and antimicrobial sensitivity testing for all patients presenting with headache, fever, stomach pains, diarrhea, or constipation at five MSC health facilities between December 2014 and January 2015. We also conducted direct observation of the residential areas of the suspected cases to assess potential environmental exposures and transmission mechanisms. Demographic, clinical, and laboratory data were entered into, and descriptive statistics were calculated with, MS Excel. RESULTS: A total of 317 patients were included in the study, with mean age 24 ± 8.1 years, and 51% female. Of the 317 suspect cases, 155 (49%) were positive by Widal antigen reaction test. A total of 188 (59%) specimens were subjected to culture and sensitivity testing, with 71 (38%) culture positive and 54 (76%), 43 (60%), and 33 (46%) sensitive to ceftriaxone, cefuroxime, and ciprofloxacin, respectively. Environmental assessments through direct observations showed that commercial and residential areas had limited (1) clean water sources, (2) latrines, and (3) hygiene stations for street food hawkers and their customers. CONCLUSIONS: Typhoid fever is endemic in MSC and causes significant disease across age and sex groups. The local health department should develop policies to (1) assure community access to potable water and hygiene stations and (2) vaccinate specific occupations, such as food and drink handlers, against typhoid.

Laboratory-acquired infections of Salmonella enterica serotype Typhi in South Africa: phenotypic and genotypic analysis of isolates.

BACKGROUND: Workers in clinical microbiology laboratories are exposed to a variety of pathogenic microorganisms. Salmonella species is among the most commonly reported bacterial causes of laboratory-acquired infections. We report on three cases of laboratory-acquired Salmonella enterica serotype Typhi (Salmonella Typhi) infection which occurred over the period 2012 to 2016 in South Africa. METHODS: Laboratory investigation included phenotypic and genotypic characterization of isolates. Phenotypic analysis included standard microbiological identification techniques, serotyping and antimicrobial susceptibility testing. Genotypic analysis included the molecular subtyping methodologies of pulsed-field gel electrophoresis analysis, multilocus sequence typing and whole-genome sequencing (WGS); with WGS data analysis including phylogenetic analysis based upon comparison of single nucleotide polymorphism profiles of isolates. RESULTS: All cases of laboratory-acquired infection were most likely the result of lapses in good laboratory practice and laboratory safety. The following critical issues were highlighted. There was misdiagnosis and misreporting of Salmonella Typhi as nontyphoidal Salmonella by a diagnostic laboratory, with associated public health implications. We highlight issues concerning the importance of accurate fluoroquinolone susceptibility testing and interpretation of results according to updated guidelines. We describe potential shortcomings of a single disk susceptibility screening test for fluoroquinolone susceptibility and suggest that confirmatory minimum inhibitory concentration testing should always be performed in cases of invasive Salmonella infections. These antimicrobial susceptibility testing issues resulted in inappropriate ciprofloxacin therapy which may have been responsible for failure in clearance of pathogen from patients. Salmonella Typhi capsular polysaccharide vaccine was not protective in one case, possibly secondarily to a faulty vaccine. CONCLUSIONS: Molecular subtyping of isolates proved effective to investigate the genetic relatedness of isolates. Molecular subtyping data interpreted together with epidemiological data allowed us to pinpoint the most likely sources for our cases of laboratory-acquired infection.

Typhoid Fever on the Half Shell.

Protecting the public from communicable infectious disease outbreaks is one of the most important, and most challenging, functions of public health. Foodborne outbreaks are not uncommon, and they can be especially difficult. This true story of the epidemiologic investigation into a typhoid fever outbreak illustrates the critical importance of timely reporting by front-line clinicians, extensive interprofessional teamwork, and statewide coordination.

A large and persistent outbreak of typhoid fever caused by consuming contaminated water and street-vended beverages: Kampala, Uganda, January - June 2015.

BACKGROUND: On 6 February 2015, Kampala city authorities alerted the Ugandan Ministry of Health of a "strange disease" that killed one person and sickened dozens. We conducted an epidemiologic investigation to identify the nature of the disease, mode of transmission, and risk factors to inform timely and effective control measures. METHODS: We defined a suspected case as onset of fever (≥37.5 °C) for more than 3 days with abdominal pain, headache, negative malaria test or failed anti-malaria treatment, and at least 2 of the following: diarrhea, nausea or vomiting, constipation, fatigue. A probable case was defined as a suspected case with a positive TUBEX® TF test. A confirmed case had blood culture yielding Salmonella Typhi. We conducted a case-control study to compare exposures of 33 suspected case-patients and 78 controls, and tested water and juice samples. RESULTS: From 17 February-12 June, we identified 10,230 suspected, 1038 probable, and 51 confirmed cases. Approximately 22.58% (7/31) of case-patients and 2.56% (2/78) of controls drank water sold in small plastic bags (ORM-H = 8.90; 95%CI = 1.60-49.00); 54.54% (18/33) of case-patients and 19.23% (15/78) of controls consumed locally-made drinks (ORM-H = 4.60; 95%CI: 1.90-11.00). All isolates were susceptible to ciprofloxacin and ceftriaxone. Water and juice samples exhibited evidence of fecal contamination. CONCLUSION: Contaminated water and street-vended beverages were likely vehicles of this outbreak. At our recommendation authorities closed unsafe water sources and supplied safe water to affected areas.

Typhoid Fever in nineteenth-century Colombia: between medical geography and bacteriology.

This paper analyses how the Colombian medical elites made sense of typhoid fever before and during the inception of bacteriological ideas and practices in the second half of the nineteenth century. Assuming that the identity of typhoid fever has to be understood within the broader concerns of the medical community in question, I show how doctors first identified Bogotá's epidemics as typhoid fever during the 1850s, and how they also attached specificity to the fever amongst other continuous fevers, such as its European and North American counterparts. I also found that, in contrast with the discussions amongst their colleagues from other countries, debates about typhoid fever in 1860-70 among doctors in Colombia were framed within the medico-geographical scheme and strongly shaped by the fear of typhoid fever appearing alongside 'paludic' fevers in the highlands. By arguing in medico-geographical and clinical terms that typhoid fever had specificity in Colombia, and by denying the medico-geographical law of antagonism between typhoid and paludic fevers proposed by the Frenchman Charles Boudin, Colombian doctors managed to question European knowledge and claimed that typhoid fever had distinct features in Colombia. The focus on paludic and typhoid fevers in the highlands might explain why the bacteriological aetiology of typhoid fever was ignored and even contested during the 1880s. Anti-Pasteurian arguments were raised against its germ identity and some physicians even supported the idea of spontaneous origin of the disease. By the 1890s, Pasteurian knowledge had come to shape clinical and hygienic practices.

Variabilidade climática, vulnerabilidade ambiental e saúde: os níveis dorio Negro e as doenças relacionadas à água em Manaus / Climate variability, vulnerability and environmental health: levels of Negro river and water-related diseases in Manaus

Manaus apresenta peculiaridades em relação às mudanças ambientais e climáticas. A sazonalidade das chuvas, níveis dos rios, produção de alimentos, pesca e condições de transporte condicionam a economia regional e influem sobre a vida na cidade. O nível da água do Rio Negro tem sido um regulador da dinâmica econômica e social da cidade, desde sua fundação. A persistência de casas de madeira construídas sobre palafitas é um exemplo de adaptação da população local à variabilidade climática. A altura das casas, pontes e trapiches sobre estacas revela uma conformação dos habitantes locais a variações esperadas do regime dos rios, ao mesmo tempo em que impõe um limite aceitável, além do qual torna-se inviável a moradia e as atividades econômicas, e consequentemente geram agravos a saúde. Nos últimos anos, o regime de cheias e vazantes tem superado as marcas históricas registradas. O objetivo desse trabalho foi analisar o comportamento hidrológico da região e relacionar seu impacto com agravos à saúde. Foi realizado um estudo de séries temporais que analisou as decomposições das séries para observação da tendência e sazonalidade. Na análise estatística utilizaram-se modelos aditivos generalizados (GAM). Os modelos multivariados também contemplaram variáveis metrológicas e Índices de Oscilação Niño (ONI). Com base nos resultados obtidos pelos modelos finais foram construídos cenários segundo a variação dos níveis do rio Negro na região de Manaus. Os resultados apontam uma associação entre eventos hidrológicos extremos e a incidência de algumas doenças na cidade. Por exemplo, cotas do rio acima de 28 metros em períodos de chuva apresentaram associação positiva com as notificações de casos de leptospirose. Os casos de febre tifoide apresentaram associação com defasagem de um mês em relação ao nível do rio Negro, temperatura máxima e índice ONI. Os casos de malária apresentaram associação com defasagem de 2 meses com a chuva e cotas acima 27,5 metros durante o período de subida do nível do rio Negro. Os resultados obtidos apontam para limiares do rio Negro na região de Manaus que podem direcionar intervenções, monitoramento, planejamento e medidas de adaptação de saúde no município.

Manaus has important specificities in the context of environmental and climate changes. Rainfall, the level of rivers, food production, the dynamic of fisheries, and transportation have a marked seasonal pattern, influencing regional economy and urban life. Rio Negro’s water level has modulated the economic and social dynamics of the city since its inception. The persistence of wood houses built on stilts is an example of how the local population has adapted to climate variability over the years. The high height of the houses, the fact bridges and piers have been built on high wooden pillars document the way local inhabitants have did their best to face the challenges posed by the rivers’ variable regimens. Despite all such flexibility, pronounced variations may exceed inhabitants’ buffering initiatives, beyond a point housing and economic activities may be no longer viable. In consequence, social and health hazards may emerge. In recent years, the cycle of ebbs and flows has exceeded historical trademarks. This study analyzed the hydrology of the region and assessed its impact on health of the local population. Time series were fitted in order to discern their overall trends and seasonal patterns. Statistical analyses used generalized additive models (GAM). Multivariate models incorporated metrological data and the Niño Oscillation Index (ONI). Models’ findings help to build scenarios focusing on the varying levels of the Rio Negro and their impact on the Manaus region. The results highlighted the association between extreme hydrological events and the incidence of different diseases in the city of Manaus.

For example, when the watermark is located 28 meters above the river’s reference level, during the rainy season, cases of leptospirosis to the surveillance systems have increased. Cases of typhoid fever were found to be associated with a one-month lagged variation of Rio Negro, maximum temperatures and variations of the ONI index. Malaria cases were associated with a two-months lagged variation of rain and a watermark 27.5 meters above Rio Negro’s reference level. Results helped to define the thresholds of Rio Negro in the Manaus region that may ask for targeted interventions, monitoring, planning, as well as to initiatives aiming to tailor health preservation to the actual conditions prevailing in the municipality.

Risk factors for typhoid outbreak in Sungai Congkak Recreational Park, Selangor 2009.

Typhoid fever continues to pose public health problems in Selangor where cases are found sporadically with occasional outbreaks reported. In February 2009, Hospital Tengku Ampuan Rahimah (HTAR) reported a cluster of typhoid fever among four children in the pediatric ward. We investigated the source of the outbreak, risk factors for the infection to propose control measures. We conducted a case-control study to identify the risk factors for the outbreak. A case was defined as a person with S. typhi isolated from blood, urine or stool and had visited Sungai Congkak recreational park on 27th January 2010. Controls were healthy household members of cases who have similar exposure but no isolation of S. typhi in blood, urine or stool. Cases were identified from routine surveillance system, medical record searching from the nearest clinic and contact tracing other than family members including food handlers and construction workers in the recreational park. Immediate control measures were initiated and followed up. Twelve (12) cases were identified from routine surveillance with 75 household controls. The Case-control study showed cases were 17 times more likely to be 12 years or younger (95% CI: 2.10, 137.86) and 13 times more likely to have ingested river water accidentally during swimming (95% CI: 3.07, 58.71). River water was found contaminated with sewage disposal from two public toilets which effluent grew salmonella spp. The typhoid outbreak in Sungai Congkak recreational park resulted from contaminated river water due to poor sanitation. Children who accidentally ingested river water were highly susceptible. Immediate closure and upgrading of public toilet has stopped the outbreak.

The decline of typhoid and the rise of non-typhoid salmonellae and fungal infections in a changing HIV landscape: bloodstream infection trends over 15 years in southern Vietnam.

The etiological spectrum of bloodstream infections is variable between industrialized and developing countries and even within a defined location over time. We investigated trends in bloodstream infections at an infectious disease hospital in Ho Chi Minh City, Vietnam, from 1994-2008. Amongst 66,111 blood cultures performed, a clinically relevant pathogen was isolated in 7645 episodes (positivity rate; 116/1000 cultures). Salmonella Typhi was the predominant pathogen until 2002; however, a considerable annual decline in the proportion of S. Typhi was observed (OR 0.6993, 95% CI [0.6885, 0.7103], p<0.0001). Conversely, there was a significant increase in the proportions of non-typhoidal Salmonella (NTS), Cryptococcus neoformans and Penicillium marneffei, concurrent with increasing HIV prevalence. These data document a substantial longitudinal shift in bloodstream infection etiology in southern Vietnam. We propose such changes are related to increasing economic prosperity and HIV prevalence, and this pattern marks a substantial change in the epidemiology of invasive salmonellosis in Southeast Asia.

Risk factors associated with typhoid fever in children aged 2-16 years in Karachi, Pakistan.

We analysed the data from the control group in a typhoid vaccine trial in Karachi to assess the differences in individual-, household- and cluster-level characteristics for developing typhoid fever. The annual incidence of typhoid in children aged 2-16 years in the control arm of the vaccine trial was 151/100 000 population. After adjustment, the risk of typhoid was lower with increasing age [risk ratio (RR) 0·89, 95% confidence interval (CI) 0·83-0·95], was higher with an increase in population density (RR 1·13, 95% CI 1·05-1·21) and was lower in the households using a safe drinking-water source (RR 0·63, 95% CI 0·41-0·99). Typhoid fever affects younger children living in areas of high population density and lack of access to safe water in Pakistan. A combination of environmental and biological interventions is required to prevent the continued epidemiological and economic impact of typhoid fever in high-risk areas of Pakistan.