East London experience with enteric fever 2007-2012

Travel vaccines-priorities determined by incidence and impact

BACKGROUND

Infectious disease epidemiology is continuously shifting. While travel has been disrupted by the COVID-19 pandemic and travel-related epidemiological research experienced a pause, further shifts in vaccine-preventable diseases (VPDs) relevant for travellers have occurred.

METHODS

We conducted a literature search on the epidemiology of travel-related VPD and synthesized data for each disease with a focus on symptomatic cases and on the impact of the respective infection among travellers, considering the hospitalization rate, disease sequela and case fatality rate. We present new data and revised best estimates on the burden of VPD relevant for decisions on priorities in travel vaccines.

RESULTS

COVID-19 has emerged to be a top travel-related risk and influenza remains high in the ranking with an estimated incidence at 1% per month of travel. Dengue is another commonly encountered infection among international travellers with estimated monthly incidence of 0.5-0.8% among non-immune exposed travellers; the hospitalized proportion was 10 and 22%, respectively, according to two recent publications. With recent yellow fever outbreaks particularly in Brazil, its estimated monthly incidence has risen to >0.1%. Meanwhile, improvements in hygiene and sanitation have led to some decrease in foodborne illnesses; however, hepatitis A monthly incidence remains substantial in most developing regions (0.001-0.01%) and typhoid remains particularly high in South Asia (>0.01%). Mpox, a newly emerged disease that demonstrated worldwide spread through mass gathering and travel, cannot be quantified regarding its travel-related risk.

CONCLUSION

The data summarized may provide a tool for travel health professionals to prioritize preventive strategies for their clients against VPD. Updated assessments on incidence and impact are ever more important since new vaccines with travel indications (e.g. dengue) have been licensed or are undergoing regulatory review.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

Typhoid fever in travellers: estimating the risk of acquisition by country

BACKGROUND

Typhoid fever is a notifiable disease within Australia. Although studies in endemic regions give an indication of acquisition risk, many countries lack reliable data, and little is known of the absolute or relative risk in Australian travellers. By combining notified case data with travel statistics provided by the Australian Bureau of Statistics, the aim of this study was to give an indication of risk for typhoid acquisition among Australian travellers.

METHODS

Australian typhoid notifications between 1st January 2010 and 30th June 2017 were grouped by country of acquisition and age category (<15 or ≥15 years). Australian travel data were used to inform time at risk and incidence rate of Australian typhoid notifications pertaining to country and region of acquisition. Salmonella Paratyphi infections, though notifiable, were excluded as the focus was vaccine preventable illness. Data from New South Wales and Victoria were used to examine the incidence in those acquiring infection in their country of birth (COB) against travellers who did not.

RESULTS

Nine hundred twenty-three cases of typhoid were notified over the period of review, 96% of which were acquired overseas. The greatest determinant of risk was travel destination, with countries in south Asia associated with highest crude incidence rate (252 per 100 000 person-years), particularly Bangladesh. Younger age and immigrants returning to their COB were generally associated with higher risk of acquisition.

CONCLUSIONS

The risk of typhoid fever in Australian travellers to endemic regions is considerable. Immigrants returning to their COB appear to be at higher risk and it is likely that this risk extends to their traveling dependents. These findings help clinicians and public health officials to plan and advise pre-travel vaccination strategies with at-risk individuals and groups. Additional sociodemographic data collection with Australian typhoid notifications would enhance the surveillance of differing international travel risk groups leaving Australia.

Typhoid and paratyphoid fever: a clinical seminar

Rationale for review: Enteric fever (EF) caused by Salmonella enterica subspecies enterica serovar Typhi (Salmonella Typhi) and S. Paratyphi (Salmonella Paratyphi) remains an important cause of infectious morbidity and mortality in many low-income countries and, therefore, still poses a major infectious risk for travellers to endemic countries. Main findings: Although the global burden of EF has decreased over the past two decades, prevalence of EF remains high in Asia and Africa, with the highest prevalence reported from the Indian subcontinent. These statistics are mirrored by data on travel-related EF. Widespread and increasing antimicrobial resistance has narrowed treatment options for travel-related EF. Ceftriaxone- and azithromycin-based therapies are commonly used, even with the emergence of extremely drug-resistant typhoid in Pakistan. Preventive measures among locals and travellers include provision of safe food and water and vaccination. Food and water precautions offer limited protection, and the efficacy of Salmonella Typhi vaccines is only moderate signifying the need for travellers to be extra cautious. Recommendations: Improvement in the diagnosis of typhoid with high degree of clinical suspicion, better diagnostic assays, early and accurate detection of resistance, therapy with appropriate drugs, improvements in hygiene and sanitation with provision of safe drinking water in endemic areas and vaccination among travellers as well as in the endemic population are keys to controlling typhoid. While typhoid vaccines are recommended for travellers to high-risk areas, moderate efficacy and inability to protect against Salmonella Paratyphi are limitations to bear in mind. Improved Salmonella Typhi vaccines and vaccines against Salmonella Paratyphi A are required.

Review of current typhoid fever vaccines, cross-protection against paratyphoid fever, and the European guidelines

INTRODUCTION

Typhoid and paratyphoid fever remain a global health problem, which - in non-endemic countries - are mainly seen in travelers, particularly in VFRs (visiting friends and relatives), with occasional local outbreaks occurring. A rise in anti-microbial resistance emphasizes the role of preventive measures, especially vaccinations against typhoid and paratyphoid fever for travelers visiting endemic countries. Areas covered: This state-of-the-art review recapitulates the epidemiology and mechanisms of disease of typhoid and paratyphoid fever, depicts the perspective of non-endemic countries and travelers (VFRs), and collectively presents current European recommendations for typhoid fever vaccination. We provide a brief overview of available (and developmental) vaccines in Europe, present current data on cross-protection to S. Paratyphi, and aim to provide a background for typhoid vaccine decision-making in travelers. Expert commentary: European recommendations are not harmonized. Experts must assess vaccination of travelers based on current country-specific recommendations. Travel health practitioners should be aware of the issues surrounding vaccination of travelers and be motivated to increase awareness of typhoid and paratyphoid fever risks.

Enteric fever among children: 50 cases in a French tertiary care centre

BACKGROUND

Enteric fever in France is primarily travel-associated. Characteristics of paediatric cases are scarce and information from field studies in endemic countries might not be generalizable to non-endemic countries.

METHODS

In this retrospective study, we reviewed all cases of typhoid and paratyphoid fever treated in a French paediatric tertiary care centre from 1993 to 2015.

RESULTS

Fifty cases of enteric fever due to Salmonella enterica serovar Typhi (n = 44) and Paratyphi (n = 6) were identified. Sixty-one percent of the children had travelled to Africa and 34% to the Indian subcontinent. Among travel-associated cases, 85% were visiting friends and relatives (VFR). Ninety-six percent had high fever associated with gastrointestinal symptoms. Anaemia (66%), elevated C-reactive protein (80%), transaminitis (87%) and mild hyponatremia (50%) were the main biological findings. Blood cultures were positive in 90% of cases. Twelve strains (24%) were resistant at least to one antibiotic, and all of them had been isolated since 2003, increasing the resistance rate during this last period to 43% (12/28). Ceftriaxone was administered to 71 patients for a median duration of 6 days (interquartile range (IQR): 4-8). The median time to apyrexia after the onset of treatment was 4 days (IQR: 2-5 days). Complications occurred in nine children with five (10%) presenting neurologic disorders. All 50 patients recovered.

CONCLUSION

In France, paediatric enteric fever is mainly a travel-associated disease and occurs in patients returning from a prolonged stay in an endemic area. Children VFR are at high risk and should be a priority target group for pre-travel preventive measures. The increase in antibiotic resistance reflects the situation in endemic countries and is a major concern.

The evolution of antimicrobial resistance in Salmonella Typhi

PURPOSE OF REVIEW

Increasing antimicrobial resistance in Salmonella Typhi is a serious public health concern, especially in industrializing countries. Here we review recent clinical and laboratory data concerning the evolution of antimicrobial resistance, with particular reference to the emergence resistance against fluoroquinolones, third generation cephalosporins, and azithromycin.

RECENT FINDINGS

The last 40 years have witnessed the sequential emergence of resistance to all first-line antimicrobials used in the treatment of S. Typhi infections. Multidrug resistance (MDR), defined by resistance to chloramphenicol, amoxicillin, and co-trimoxazole, emerged in the 1990s, followed rapidly by reduced susceptibility to fluoroquinolones. In the current decade, high-level fluoroquinolone resistance has emerged in south Asia and threatens to spread worldwide. Increasing reliance is now being placed on the activity of third generation cephalosporins and azithromycin, but resistance against these agents is developing. Carbapenems and tigecycline may be alternatives, although clinical data are sparse, and in some settings reversion to chloramphenicol and co-trimoxazole susceptibility is occurring. Therefore, older drugs may yet have a role in the treatment of S. Typhi infections.

SUMMARY

Good surveillance, improved diagnostics, more prudent use of antimicrobials, and effective vaccines will all be critical to reducing the burden of disease caused by S. Typhi.

Baseline Antibody Titre against Salmonella enterica in Healthy Population of Mumbai, Maharashtra, India

Objective

The aim of this study was to establish a baseline titre for the population of Mumbai, Maharashtra, India.

Method

Four hundred healthy blood donors, attending blood donation camps, were screened using a survey questionnaire. Widal tube agglutination test was performed on the diluted sera (with 0.9% normal saline) of blood donors, with final dilution ranging from 1 : 40 to 1 : 320.

Results

Out of 400 individuals providing samples, 78 (19.5%) individuals showed antibody titres ≥ 1 : 40 for at least one antigen and 322 (80.5%) showed no agglutination. The baseline antibody titres against O antigen and H antigen of Salmonella enterica serotype Typhi were found to be 1 : 40 and 1 : 80, respectively. Similarly, the baseline antibody titres for the H antigen of Salmonella enterica serotypes Paratyphi A and Paratyphi B were found to be 1 : 40 and 1 : 80, respectively.

Conclusion

Thus, it was noted that the diagnostically significant cutoff of antibody titre from acute phase sample was ≥ 1 : 80 for S. Typhi O antigen and titre of ≥ 1 : 160 for both S. Typhi H antigen and S. Paratyphi BH antigen. Antibody titre of ≥ 1 : 80 can be considered significant for S. Paratyphi AH antigen.