International travel is thought to be a major risk factor for developing gastrointestinal (GI) illness for UK residents. Here, we present an analysis of routine laboratory and exposure surveillance data from North East (NE) England, describing the destination-specific contribution that international travel makes to the regional burden of GI infection.

Laboratory reports of common notifiable enteric infections were linked to exposure data for cases reported between 1 January 2013 and 31 December 2022. Demographic characteristics of cases were described, and rates per 100,000 visits were determined using published estimates of overseas visits from the Office for National Statistics (ONS) International Passenger Survey (IPS).

About 34.9% of cases reported international travel during their incubation period between 2013 and 2022, although travel-associated cases were significantly reduced (>80%) during the COVID-19 pandemic. Between 2013 and 2019, half of Shigella spp. and non-typhoidal Salmonella infections and a third of Giardia sp., Cryptosporidium spp., and Shiga toxin-producing Escherichia coli (STEC) infections were reported following travel. Rates of illness were highest in travellers returning from Africa and Asia (107.8 and 61.1 per 100,000 visits), with high rates also associated with tourist resorts like Turkey, Egypt, and the Dominican Republic (386.4–147.9 per 100,000 visits).

International travel is a major risk factor for the development of GI infections. High rates of illness were reported following travel to both destinations, which are typically regarded as high-risk and common tourist resorts. This work highlights the need to better understand risks while travelling to support the implementation of guidance and control measures to reduce the burden of illness in returning travellers.

Stepwise non-pharmaceutical interventions and health system changes implemented as part of the COVID-19 response have had implications on the incidence, diagnosis, and reporting of other communicable diseases. Here, we established the impact of the COVID-19 outbreak response on gastrointestinal (GI) infection trends using routinely collected surveillance data from six national English laboratory, outbreak, and syndromic surveillance systems using key dates of governmental policy to assign phases for comparison between pandemic and historic data. Following decreases across all indicators during the first lockdown (March–May 2020), bacterial and parasitic pathogens associated with foodborne or environmental transmission routes recovered rapidly between June and September 2020, while those associated with travel and/or person-to-person transmission remained lower than expected for 2021. High out-of-season norovirus activity was observed with the easing of lockdown measures between June and October 2021, with this trend reflected in laboratory and outbreak systems and syndromic surveillance indicators. Above expected increases in emergency department (ED) attendances may have reflected changes in health-seeking behaviour and provision. Differential reductions across specific GI pathogens are indicative of the underlying routes of transmission. These results provide further insight into the drivers for transmission, which can help inform control measures for GI infections.

Shiga toxin-producing Escherichia coli (STEC) serogroup O157 is a zoonotic, foodborne gastrointestinal pathogen of major public health concern. We describe the epidemiology of STEC O157 infection in England by exploring the microbiological and clinical characteristics, the demographic and geographical distribution of cases, and examining changes in environmental exposures over 11 years of enhanced surveillance. Enhanced surveillance data including microbiological subtyping, clinical presentations and exposures were extracted for all cases resident in England with evidence of STEC O157 infection, either due to faecal culture or serology detection. Incidence rates were calculated based on mid-year population estimates from the Office of National Statistics (ONS). Demographics, geography, severity and environmental exposures were compared across the time periods 2009–2014 and 2015–2019. The number of cases reported to national surveillance decreased, with the mean cases per year dropping from 887 for the period 2009–2014 to 595 for the period 2015–2019. The decline in STEC O157 infections appears to be mirrored by the decrease in cases infected with phage type 21/28. Although the percentage of cases that developed HUS decreased, the percentage of cases reporting bloody diarrhoea and hospitalisation remained stable. The number of outbreaks declined over time, although more refined typing methods linked more cases to each outbreak. Integration of epidemiological data with microbiological typing data is essential to understanding the changes in the burden of STEC infection, assessment of the risks to public health, and the prediction and mitigation of emerging threats.

Recurrent outbreaks of haemolytic uraemic syndrome (HUS) caused by Shiga toxin-producing Escherichia coli (STEC) serotype O55:H7 occurred in England between 2014 and 2018. We reviewed the epidemiological evidence to identify potential source(s) and transmission routes of the pathogen, and to assess the on-going risk to public health. Over the 5-year period, there were 43 confirmed and three probable cases of STEC O55:H7. The median age of cases was 4 years old (range 6 months to 69 years old) and over half of all cases were female (28/46, 61%). There were 36/46 (78.3%) symptomatic cases, and over half of all cases developed HUS (25/46, 54%), including two fatal cases. No common food or environmental exposures were identified, although the majority of cases lived in rural or semi-rural environments and reported contact with both wild and domestic animals. This investigation informed policy on the clinical and public health management of HUS caused by STEC other than serotype O157:H7 (non-O157 STEC) in England, including comprehensive testing of all household contacts and household pets and more widespread use of polymerase chain reaction assays for the rapid diagnosis of STEC-HUS.

In April 2018, Public Health England was notified of cases of Shigella sonnei who had eaten food from three different catering outlets in England. The outbreaks were initially investigated as separate events, but whole-genome sequencing (WGS) showed they were caused by the same strain. The investigation included analyses of epidemiological data, the food chain and microbiological examination of food samples. WGS was used to determine the phylogenetic relatedness and antimicrobial resistance profile of the outbreak strain. Ultimately, 33 cases were linked to this outbreak; the majority had eaten food from seven outlets specialising in Indian or Middle Eastern cuisine. Five outlets were linked to two or more cases, all of which used fresh coriander although a shared supplier was not identified. An investigation at one of the venues recorded that 86% of cases reported eating dishes with coriander as an ingredient or garnish. Four cases were admitted to hospital and one had evidence of treatment failure with ciprofloxacin. Phylogenetic analysis showed that the outbreak strain was part of a wider multidrug-resistant clade associated with travel to Pakistan. Poor hygiene practices during cultivation, distribution or preparation of fresh produce are likely contributing factors.

We investigated a large gastroenteritis outbreak that occurred in Northern Greece in 2019. A case was defined as anyone presenting with diarrhoea and/or vomiting from 24 January 2019 to 04 February 2019. We conducted a case-control study (CCS) using random selection of participants >16 years of age, residents of town X, who visited the health care centre between 25 and 28 January 2019. Moreover, we conducted a retrospective cohort study (CS) at the four elementary schools of the town. We collected clinical and water samples and the water supply system was inspected. In total, we recorded 638 cases (53% female; median age was 44 years (range 0–93)). Forty-eight cases and 52 controls participated in the CCS and 236 students in the CS. Both CCS and CS indicated tap water as the most likely source (OR 10, 95% CI 2.09–93.4, explaining 95.7% of cases; RR = 2.22, 95% CI 1.42–3.46, respectively). More than one pathogen was detected from stool samples of 6 of the 11 cases tested (norovirus, Campylobacter jejuni, Enterohemorrhagic E. coli (EHEC) and Enteropathogenic E. coli (EPEC)). Water samples, collected after ad-hoc chlorination, tested negative. Technical failures of the water tanks' status were identified. Our results suggested a waterborne outbreak. We recommended regular monitoring of the water supply system and immediate repair of technical failures.

In November 2017, Public Health England identified an outbreak of Shiga toxin-producing Escherichia coli O157:H7 in England where whole genome sequencing results indicated cases were likely to be linked to a common source, and began investigations. Hypothesis generation included a review of enhanced surveillance data, a case-case study and trawling interviews. The hypothesis of interest was tested through the administration of focussed questionnaires and review of shopping history using loyalty card data. Twelve outbreak cases were detected, eight were hospitalised and four developed haemolytic uraemic syndrome. Frozen beef burgers supplied by a national retailer were identified as the vehicle of the outbreak. Testing of two left-over burger samples obtained from the freezers of two separate (unlinked) cases and a retained sample from the production premises were tested and found to be positive for the outbreak strain. A voluntary recall of the burgers was implemented by the retailer. Investigations at the production premises identified no contraventions of food safety legislation. Cooking guidance on the product packaging was deemed to be adequate and interviews with the cases/carers who prepared the burgers revealed no deficiencies in cooking practices at home. Given the long-shelf life of frozen burgers, the product recall likely prevented more cases.

We collected monthly reports on gastrointestinal illness (GII) episodes among 2348 adults in a 1-year cohort in South West Sweden. The GII episodes were collected by SMS (Short Message System) and validated by telephone interviews among the cohort participants and nationwide. The annual incidence was 0.64 and 0.43 cases per person-year for 28-day self-defined GII (any symptom) and acute GII (vomiting and/or ≥3 episodes of diarrhoea), respectively. The incidence was about 20% higher for the 14-day recall, compared with 28-day recall. The duration of illness was on average 2.3 days. We observed a unimodal seasonal distribution of GII, with the highest prevalence during winter. Responses collected by SMS highly correlated with responses collected by telephone. SMS survey was an efficient tool for the collection of repeated estimates of GII.

Systematic, national surveillance of outbreaks of intestinal infectious disease has been undertaken by Public Health England (PHE) since 1992. Between 1992 and 2002, there were 19 outbreaks linked to raw drinking milk (RDM) or products made using raw milk, involving 229 people; 36 of these were hospitalised. There followed an eleven-year period (2003–2013) where no outbreaks linked to RDM were reported. However, since 2014 seven outbreaks of Escherichia coli O157:H7 (n = 3) or Campylobacter jejuni (n = 4) caused by contaminated RDM were investigated and reported. Between 2014 and 2017, there were 114 cases, five reported hospitalisations and one death. The data presented within this review indicated that the risk of RDM has increased since 2014. Despite the labelling requirements and recommendations that children should not consume RDM, almost a third of outbreak cases were children. In addition, there has been an increase in consumer popularity and in registered RDM producers in the UK. The Food Standards Agency (FSA) continue to provide advice on RDM to consumers and have recently made additional recommendations to enhance existing controls around registration and hygiene of RDM producers.

Shiga toxin-producing Escherichia coli (STEC) infection can cause serious illness including haemolytic uraemic syndrome. The role of socio-economic status (SES) in differential clinical presentation and exposure to potential risk factors amongst STEC cases has not previously been reported in England. We conducted an observational study using a dataset of all STEC cases identified in England, 2010–2015. Odds ratios for clinical characteristics of cases and foodborne, waterborne and environmental risk factors were estimated using logistic regression, stratified by SES, adjusting for baseline demographic factors. Incidence was higher in the highest SES group compared to the lowest (RR 1.54, 95% CI 1.19–2.00). Odds of Accident and Emergency attendance (OR 1.35, 95% CI 1.10–1.75) and hospitalisation (OR 1.71, 95% CI 1.36–2.15) because of illness were higher in the most disadvantaged compared to the least, suggesting potential lower ascertainment of milder cases or delayed care-seeking behaviour in disadvantaged groups. Advantaged individuals were significantly more likely to report salad/fruit/vegetable/herb consumption (OR 1.59, 95% CI 1.16–2.17), non-UK or UK travel (OR 1.76, 95% CI 1.40–2.27; OR 1.85, 95% CI 1.35–2.56) and environmental exposures (walking in a paddock, OR 1.82, 95% CI 1.22–2.70; soil contact, OR 1.52, 95% CI 2.13–1.09) suggesting other unmeasured risks, such as person-to-person transmission, could be more important in the most disadvantaged group.

In this study, we estimate the burden of foodborne illness (FBI) caused by five major pathogens among nondeployed US Army service members. The US Army is a unique population that is globally distributed, has its own food procurement system and a food protection system dedicated to the prevention of both unintentional and intentional contamination of food. To our knowledge, the burden of FBI caused by specific pathogens among the US Army population has not been determined. We used data from a 2015 US Army population survey, a 2015 US Army laboratory survey and data from FoodNet to create inputs for two model structures. Model type 1 scaled up case counts of Campylobacter jejuni, Shigella spp., Salmonella enterica non-typhoidal and STEC non-O157 ascertained from the Disease Reporting System internet database from 2010 to 2015. Model type 2 scaled down cases of self-reported acute gastrointestinal illness (AGI) to estimate the annual burden of Norovirus illness. We estimate that these five pathogens caused 45 600 (5%–95% range, 30 300–64 000) annual illnesses among nondeployed active duty US Army Service members. Of these pathogens, Norovirus, Campylobacter jejuni and Salmonella enterica non-typhoidal were responsible for the most illness. There is a tremendous burden of AGI and FBI caused by five major pathogens among US Army Soldiers, which can have a tremendous impact on readiness of the force. The US Army has a robust food protection program in place, but without a specific active FBI surveillance system across the Department of Defence, we will never have the ability to measure the effectiveness of modern, targeted, interventions aimed at the reduction of specific foodborne pathogens.

Throughout history, acute gastrointestinal illness (AGI) has been a significant cause of morbidity and mortality among US service members. We estimated the magnitude, distribution, risk factors and care seeking behaviour of AGI among the active duty US Army service members using a web-based survey. The survey asked about sociodemographic characteristics, dining and food procurement history and any experience of diarrhoea in the past 30 days. If respondents reported diarrhoea, additional questions about concurrent symptoms, duration of illness, medical care seeking and stool sample submission were asked. Univariable and multivariable logistic regression were used to identify the factors associated with AGI and factors associated with seeking care and submitting a stool sample. The 30-day prevalence of AGI was 18.5% (95% CI 16.66–20.25), the incidence rate was 2.24 AGI episodes per person-year (95% CI 2.04–2.49). Risk factors included a region of residence, eating at the dining facility and eating at other on-post establishments. Individuals with AGI missed 2.7–3.7 days of work, which costs approximately $ 847 451 629 in paid wages. Results indicate there are more than 1 million cases of AGI per year among US Army Soldiers, which can have a major impact on readiness. We found that care-seeking behaviours for AGI are different among US Army Service Members than the general population. Army Service Members with AGI report seeking care and having a stool sample submitted less often, especially for severe (bloody) diarrhoea. Factors associated with seeking care included rank, experiencing respiratory symptoms (sore throat, cough), experiencing vomiting and missing work for their illness. Factors associated with submitting a stool sample including experiencing more than five loose stools in 24 h and not experiencing respiratory symptoms. US Army laboratory-based surveillance under-estimates service members with both bloody and non-bloody diarrhoea. To our knowledge, this is the first study to estimate the magnitude, distribution, risk factors and care-seeking behaviour of AGI among Army members. We determined Army service members care-seeking behaviours, AGI risk factors and stool sample submission rates are different than the general population, so when estimating burden of AGI caused by specific foodborne pathogens using methods like Scallan et al. (2011), unique multipliers must be used for this subset of the population. The study legitimises not only the importance of AGI in the active duty Army population but also highlights opportunities for public health leaders to engage in simple strategies to better capture AGI impact so more modern intervention strategies can be implemented to reduce burden and indirectly improve operational readiness across the Enterprise.

In the autumn of 2018, an outbreak of cryptosporidiosis affected adult employees from the same company in Western Norway. The organism was Cryptosporidium parvum, GP60 subtype IIaA14G1R1. All those infected had drunk from the same container of self-pressed apple juice. Incubation period (1 week) and clinical signs were similar among those infected, although some experienced a more prolonged duration of symptoms (up to 2–3 weeks) than others. The infections resulted after consumption from only one of 40 containers of juice and not from any of the other containers. It seems that although Cryptosporidium oocysts were detected in a sample from another container, the contamination did not affect the whole batch. This is perhaps indicative of a restricted contamination event, either from contaminated ground in the orchard, or during collection of the fruit, or during processing. Although outbreaks of food-borne cryptosporidiosis have previously been associated with consumption of contaminated apple juice, most of the more recent outbreaks of food-borne cryptosporidiosis have been associated with salad vegetables or herbs. This outbreak, the first outside USA reported to be associated with apple juice, is a timely reminder that such juice is a suitable transmission vehicle for Cryptosporidium oocysts, and that appropriate hygienic measures are essential in the production of such juice, including artisanal (non-commercial) production.

Norovirus (NoV) is the greatest cause of infectious intestinal disease in the UK. The burden associated with foodborne outbreaks is underestimated in part because data are dispersed across different organisations. Each looks at outbreaks through a different lens. To estimate the burden of NoV from seafood including shellfish we used a capture-recapture technique using datasets from three different organisations currently involved in collecting information on outbreaks. The number of outbreaks of NoV related to seafood including shellfish in England was estimated for the period of 2004–2011. The combined estimates were more than three times as high (N = 360 using Chao's sample coverage approach) as the individual count from organisation three (N = 115), which captured more outbreaks than the other two organisations. The estimates were calculated for both independence and dependence between the datasets. There was evidence of under-reporting of NoV outbreaks and inconsistency of reporting between organisations, which means that, currently, more than one data source needs to be used to estimate as accurately as possible the total number of NoV outbreaks and associated cases. Furthermore, either the integration of reporting mechanisms or simplifying the process of reporting outbreaks to organisations is essential for understanding and, hence, controlling disease burden.

A gastrointestinal outbreak was reported among 154 diners who attended a Christmas buffet on the 9 and 10 December 2016. A retrospective cohort study was undertaken. Faecal samples, water, ice and an air ventilation device were tested for indicators and routine pathogens. Altogether 26% (24/91) fulfilled the case definition of having typical viral gastrointestinal symptoms. Norovirus genogroup I was detected in faecal samples from three cases. One of these cases tested positive also for sapovirus and had a family member testing positive for both norovirus and sapovirus. A diner who drank water or drinks with ice cubes (risk ratios (RR) 6.5, 95% confidence intervals (CI) 1.5–113.0) or both (RR 8.2, 95% CI 1.7–145.5) had an increased risk in a dose-response manner. Ice cubes from three vending machines had high levels of heterotrophic bacteria. A faulty air ventilation valve in the space where the ice cube machine was located was considered a likely cause of this outbreak. Leaking air ventilation valves may represent a neglected route of transmission in viral gastrointestinal outbreaks.

Given the challenges in accurately identifying unexposed controls in case–control studies of diarrhoea, we examined diarrhoea incidence, subclinical enteric infections and growth stunting within a reference population in the Global Enteric Multicenter Study, Kenya site. Within ‘control’ children (0–59 months old without diarrhoea in the 7 days before enrolment, n = 2384), we examined surveys at enrolment and 60-day follow-up, stool at enrolment and a 14-day post-enrolment memory aid for diarrhoea incidence. At enrolment, 19% of controls had ⩾1 enteric pathogen associated with moderate-to-severe diarrhoea (‘MSD pathogens’) in stool; following enrolment, many reported diarrhoea (27% in 7 days, 39% in 14 days). Controls with and without reported diarrhoea had similar carriage of MSD pathogens at enrolment; however, controls reporting diarrhoea were more likely to report visiting a health facility for diarrhoea (27% vs. 7%) or fever (23% vs. 16%) at follow-up than controls without diarrhoea. Odds of stunting differed by both MSD and ‘any’ (including non-MSD pathogens) enteric pathogen carriage, but not diarrhoea, suggesting control classification may warrant modification when assessing long-term outcomes. High diarrhoea incidence following enrolment and prevalent carriage of enteric pathogens have implications for sequelae associated with subclinical enteric infections and for design and interpretation of case–control studies examining diarrhoea.

A total of 592 people reported gastrointestinal illness following attendance at Street Spice, a food festival held in Newcastle-upon-Tyne, North East England in February/March 2013. Epidemiological, microbiological and environmental investigations were undertaken to identify the source and prevent further cases. Several epidemiological analyses were conducted; a cohort study; a follow-up survey of cases and capture re-capture to estimate the true burden of cases. Indistinguishable isolates of Salmonella Agona phage type 40 were identified in cases and on fresh curry leaves used in one of the accompaniments served at the event. Molecular testing indicated entero-aggregative Escherichia coli and Shigella also contributed to the burden of illness. Analytical studies found strong associations between illness and eating food from a particular stall and with food items including coconut chutney which contained fresh curry leaves. Further investigation of the food supply chain and food preparation techniques identified a lack of clear instruction on the use of fresh uncooked curry leaves in finished dishes and uncertainty about their status as a ready-to-eat product. We describe the investigation of one of the largest outbreaks of food poisoning in England, involving several gastrointestinal pathogens including a strain of Salmonella Agona not previously seen in the UK.

Detecting gastrointestinal (GI) infection transmission among men who have sex with men (MSM) in England is complicated by a lack of routine sexual behavioural data. We investigated whether gender distributions might generate signals for increased transmission of GI pathogens among MSM. We examined the percentage male of laboratory-confirmed patient-episodes for patients with no known travel history for 10 GI infections of public health interest in England between 2003 and 2013, stratified by age and region. An adult male excess was observed for Shigella spp. (annual maximum 71% male); most pronounced for those aged 25–49 years and living in London, Brighton and Manchester. An adult male excess was observed every year for Entamoeba histolytica (range 59.8–76.1% male), Giardia (53.1–57.6%) and Campylobacter (52.1–53.5%) and for a minority of years for hepatitis A (max. 69.8%) and typhoidal salmonella (max. 65.7%). This approach generated a signal for excess male episodes for six GI pathogens, including a characterised outbreak of Shigella among MSM. Stratified analyses by geography and age group were consistent with MSM transmission for Shigella. Optimisation and routine application of this technique by public health authorities elsewhere might help identify potential GI infection outbreaks due to sexual transmission among MSM, for further investigation.