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.

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.

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.

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.

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.

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.

Risk factors for typhoid in Darjeeling, West Bengal, India: evidence for practical action.

OBJECTIVE: To identify risk factors for typhoid and propose prevention measures. METHODS: Case-control study; we compared hospital-based typhoid cases defined as fever>38 degrees C for >or=3 days with four-fold rise in 'O' antibodies on paired sera (Widal) with community, age and neighbourhood matched controls. We obtained information on drinking water, fruits, vegetables, milk products and sanitation; and calculated matched odds ratios (MOR) and attributable fractions in the population (AFP) for the risk factors or failure to use prevention measures. RESULTS: The 123 typhoid cases (median age: 25 years, 47% female) and 123 controls did not differ with respect to baseline characteristics. Cases were less likely to store drinking water in narrow-mouthed containers (MOR: 0.4, 95% CI: 0.2-0.7, AFP 29%), tip containers to draw water (MOR: 0.4, 95% CI: 0.2-0.7, AFP 33%) and have home latrines (MOR: 0.5, 95% CI: 0.3-0.8, AFP 23%). Cases were more likely to consume butter (OR: 2.3, 95% CI: 1.3-4.1, AFP 28%), yoghurt (OR: 2.3, 95% CI: 1.4-3.7, AFP 34%) and raw fruits and vegetables, including onions (MOR: 2.1, 95% CI: 1.2-3.9, AFP 34%), cabbages (OR: 2.8, 95% CI: 1.7-4.8, AFP 44%) and unwashed guavas (OR: 1.9, 95% CI: 1.2-3, AFP 25%). CONCLUSION: Typhoid was associated with unsafe water and sanitation practices as well as with consumption of milk products, fruits and vegetables. We propose to chlorinate drinking water at the point of use, wash/cook raw fruits and vegetables and ensure safer preparation/storage of local milk products.

Risk of communicable disease infection associated with wastewater irrigation in agricultural settlements.

The incidence of enteric communicable diseases in 77 kibbutzim (agricultural communal settlements) practicing wastewater spray irrigation with partially treated nondisinfected oxidation pond effluent is compared with that in 130 kibbutzim practicing no form of wastewater irrigation. The incidence of shigellosis, salmonellosis, typhoid fever, and infectious hepatitis is two to four times higher in communities practicing wastewater irrigation. No significant differences are found for the incidence of streptococcal infections, tuberculosis, and laboratory-confirmed cases of influenza. Nor are differences found for enteric disease rates during the winter nonirrigation season. Strong wastewater treatment measures, including effective bacterial and viral inactivation through disinfection, are recommended for all cases of sewage irrigation or land disposal near residential areas in light of the potential public health risks involved.

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.

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.

Molecular evolution of Salmonella enterica serovar Typhimurium and pathogenic Escherichia coli: from pathogenesis to therapeutics.

Salmonella enterica serovar Typhimurium (S. Typhimurium) and certain Escherichia coli are human pathogens that have evolved through the acquisition of multiple virulence determinants by horizontal gene transfer. Similar genetic elements, as pathogenicity islands and virulence plasmids, have driven molecular evolution of virulence in both species. In addition, the contribution of prophages has been recently highlighted as a reservoir for pathogenic diversity. Characterization of horizontally acquired virulence genes has several clinical implications. First, identification of virulence determinants that have a sporadic distribution and are specifically associated with a pathotype and/or a pathology can be useful markers for risk assessment and diagnosis. Secondly, virulence factors widely distributed in pathogenic strains, but absent from non-pathogenic bacteria, are interesting targets for the development of novel antimicrobial chemotherapies and vaccines. Here, we summarize the horizontally acquired virulence factors of S. Typhimurium, enterohemorrhagic E. coli O157:H7 and uropathogenic E. coli, and we describe their use in novel therapeutic approaches.

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.

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.

Epidemiology and clinical aspects of enteric fever in Israel.

Enteric fever decreased in Israel in the last 50 years, but its current epidemiology is unknown. In a nationwide study, we evaluated all cases of enteric fever from 1995 to 2003. On hundred thirty-six cases met the case definition. During the period studied, the incidence of enteric fever decreased from 0.42 to 0.23/100,000. A total of 57.4% of the cases were acquired abroad. The incidence of endemic enteric fever was 2.7 times higher in Arabs than in Jews. In Arabs, Salmonella Typhi was the causative agent in all cases, and almost all cases were endemic. In Jews, most cases were imported, with a decrease in imported S. typhi, cases and an increase in imported S. Paratyphi A cases. Salmonella Paratyphi B was endemic, and restricted to the Jewish population. The reasons for the difference in causative agents along ethnic lines need further evaluation. A more efficient vaccine for travelers that includes S. Paratyphi A is needed.

Hepatitis A, typhoid and malaria among travelers--surveillance data from Québec (Canada).

Analysis of epidemiological data on health problems related to international travel helps put into perspective preventive interventions for travelers. To document the epidemiological context of travel health interventions in Québec, we reviewed surveillance data for three infectious diseases. The analysis included data collected in the notifiable diseases surveillance system for hepatitis A, typhoid, and malaria cases reported from 2000 to 2002. Additional data were obtained from the provincial hepatitis risk factor database as well as from regional public health departments. More than 40% of cases of hepatitis A for which risk factor information is available are associated with international travel; 20% of these cases were contracted in Mexico and 22% in the West Indies. The risk of acquiring hepatitis A seems to be higher among travelers under 35 years of age; also, given the number of Quebecers traveling to all regions of the world, this risk is proportionally higher in Africa. Data gathered for typhoid indicate that the risk to travelers from Québec is proportionately higher for Quebecers traveling to the Indian subcontinent and whose purpose is to visit family and friends, and for those who stay abroad for 4 weeks or longer. The risk of malaria is greater in Africa (where contracted cases are mostly caused by Plasmodium falciparum). Over half of malaria cases involve individuals traveling abroad for business (including volunteerism), and almost 75% contracted the disease during a stay of a month or more. Nearly half of the cases had not taken chemoprophylaxis. Available data have limitations for infectious disease surveillance among Québec travelers: imprecise number of cases (underdiagnosis and underreporting), imprecise denominators (number of travelers), and lack of data on the characteristics of trips taken. However, despite its limitations, this profile of infectious diseases among travelers from Québec provides interesting data for preventive intervention.

Risk of travel-associated typhoid and paratyphoid fevers in various regions.

BACKGROUND: Although enteric fever (typhoid and paratyphoid fevers) is a major global public health problem, comparable data on the risks of contracting travel-associated enteric fever in various regions of the world are scarce. METHODS: From the Swedish database on notifiable communicable diseases, we retrieved all case records from 1997 to 2003 on typhoid and paratyphoid fevers. The data set was compared with data on travel patterns obtained from a comprehensive travel database with information from interviews with more than 16,000 Swedish residents with recent overnight travel outside Sweden. RESULTS: The overall risk of being notified with enteric fever after travel was 0.42 in 100,000 travelers. The highest risk for typhoid fever was seen in travelers from India and neighboring countries (41.7 in 100,000), the Middle East (5.91 in 100,000), and Central Africa (3.33 in 100,000), whereas the risk was comparatively low in East Asia (0.24 in 100,000). Almost the same risk areas stood out for paratyphoid fever: India and neighbors (37.5 in 100,000), the Middle East (3.64 in 100,000), and East Africa (3.33 in 100,000). The epidemiology of paratyphoid fever was considerably affected by a large outbreak of paratyphoid B in a Turkish tourist resort in 1999. The youngest children were at highest risk for typhoid fever (odds ratio 44.2), whereas youths ages 7 to 18 years were at highest risk for paratyphoid fever (odds ratio 9.7). CONCLUSIONS: Detailed risk data for enteric fever after travel could form the basis for travel advice. Vaccination against typhoid fever should always be considered for travelers to the Indian subcontinent, the Middle East, and Africa but should not routinely be given to travelers to the Malay Peninsula.