Causal mechanisms of norovirus outbreaks are often not revealed. Understanding the transmission route (e.g. foodborne, waterborne, or environmental) and vehicle (e.g. shellfish or recreational water) of a norovirus outbreak, however, is of great public health importance; this information can facilitate interventions for an ongoing outbreak and regulatory action to limit future outbreaks. Towards this goal, we conducted a systematic review to examine whether published outbreak information was associated with the implicated transmission route or vehicle. Genogroup distribution was associated with transmission route and food vehicle, but attack rate and the presence of GII.4 strain were not associated with transmission route, food vehicle, or water vehicle. Attack rate, genogroup distribution, and GII.4 strain distribution also varied by other outbreak characteristics (e.g. setting, season, hemisphere). These relationships suggest that different genogroups exploit different environmental conditions and thereby can be used to predict the likelihood of various transmission routes or vehicles.

Norovirus is a common cause of gastroenteritis in all ages. Typical infections cause viral shedding periods of days to weeks, but some individuals can shed for months or years. Most norovirus risk models do not include these long-shedding individuals, and may therefore underestimate risk. We reviewed the literature for norovirus-shedding duration data and stratified these data into two distributions: regular shedding (mean 14–16 days) and long shedding (mean 105–136 days). These distributions were used to inform a norovirus transmission model that predicts the impact of long shedders. Our transmission model predicts that this subpopulation increases the outbreak potential (measured by the reproductive number) by 50–80%, the probability of an outbreak by 33%, the severity of transmission (measured by the attack rate) by 20%, and transmission duration by 100%. Characterizing and understanding shedding duration heterogeneity can provide insights into community transmission that can be useful in mitigating norovirus risk.

Multiple norovirus outbreaks following catered events in Auckland, New Zealand, in September 2010 were linked to the same catering company and investigated. Retrospective cohort studies were undertaken with attendees of two events: 38 (24·1%) of 158 surveyed attendees developed norovirus-compatible illness. Attendees were at increased risk of illness if they had consumed food that had received manual preparation following cooking or that had been prepared within 45 h following end of symptoms in a food handler with prior gastroenteritis. All food handlers were tested for norovirus. A recombinant norovirus GII.e/GII.4 was detected in specimens from event attendees and the convalescent food handler. All catering company staff were tested; no asymptomatic norovirus carriers were detected. This investigation improved the characterization of norovirus risk from post-symptomatic food handlers by narrowing the potential source of transmission to one individual. Food handlers with gastroenteritis should be excluded from the workplace for 45 h following resolution of symptoms.

We describe an outbreak of simultaneous Clostridium difficile and norovirus infections in a long-term-care facility. Thirty patients experienced acute gastroenteritis, and four had co-infection with identical C. difficile 027 and genotype II.4 New Orleans norovirus strains. Co-occurring infection requires improved understanding of risk factors, clinical impact, and testing strategies.

Non-typhoidal Salmonella are an important but poorly characterized cause of paediatric diarrhoea in developing countries. We conducted a hospital-based case-control study in children aged <5 years in Ho Chi Minh City to define the epidemiology and examine risk factors associated with Salmonella diarrhoeal infections. From 1419 diarrhoea cases and 571 controls enrolled between 2009 and 2010, 77 (5·4%) diarrhoea cases were stool culture-positive for non-typhoidal Salmonella. Salmonella patients were more likely to be younger than controls (median age 10 and 12 months, respectively) [odds ratio (OR) 0·97; 95% confidence interval (CI) 0·94–0·99], to report a recent diarrhoeal contact (8·1% cases, 1·8% controls; OR 5·98, 95% CI 1·8–20·4) and to live in a household with >2 children (cases 20·8%, controls 10·2%; OR 2·32, 95% CI 1·2–4·7). Our findings indicate that Salmonella are an important cause of paediatric gastroenteritis in this setting and we suggest that transmission may occur through direct human contact in the home.

Strain characteristics of 51 Shigella sonnei isolates obtained from children seeking medical care (MC) and 48 isolates recovered during a prospective diarrhoea birth cohort (BC) study were compared. Biochemical characterization and antibiotic susceptibility testing determined that all S. sonnei isolates were biotype g and multidrug-resistant. Plasmid profiling identified 15 closely related patterns and XbaI pulsed-field gel electrophoresis confirmed the high degree of genetic similarity between isolates. All S. sonnei isolates harboured ipaH and class II integrase genes and 84·3 and 80% of the MC and BC isolates, respectively carried the sen gene. Neither the class I integrase nor the set gene was detected. Our results indicate that S. sonnei isolates associated with severe diarrhoea were indistinguishable from those associated with mild diarrhoea. Additional genetic tests with greater discrimination might offer an opportunity to determine genetic differences within the globally disseminating biotype g clone.

By building reconstruction models for a case of gastroenteritis in the general population moving through different steps of the surveillance pyramid we estimated that millions of illnesses occur annually in the European population, leading to thousands of hospitalizations. We used data on the healthcare system in seven European Union member states in relation to pathogen characteristics that influence healthcare seeking. Data on healthcare usage were obtained by harmonized cross-sectional surveys. The degree of under-diagnosis and underreporting varied by pathogen and country. Overall, underreporting and under-diagnosis were estimated to be lowest for Germany and Sweden, followed by Denmark, The Netherlands, UK, Italy and Poland. Across all countries, the incidence rate was highest for Campylobacter spp. and Salmonella spp. Incidence estimates resulting from the pyramid reconstruction approach are adjusted for biases due to different surveillance systems and are therefore a better basis for international comparisons than reported data.

In 2010, 7/44 (16%) reported foodborne outbreaks in Finland were linked with raw beetroot consumption. We reviewed data from the national outbreak registry in order to hypothesize the aetiology of illness and to prevent further outbreaks. In the seven outbreaks, 124 cases among 623 respondents were identified. Consumption of raw beetroot was strongly associated with gastrointestinal illness (relative risk 8·99, 95% confidence interval 6·06–13·35). The illness was characterized by sudden onset of gastrointestinal symptoms; the median incubation time was 40 min and duration of illness 5 h. No common foodborne pathogens or toxins were found in either clinical or beetroot samples, but all tested beetroot samples were of poor quality according to total bacterial counts. Beta-haemolytic Pseudomonas fluorescens was detected in several beetroot samples but its effect on human health is unknown. No outbreaks were reported after the Finnish Food Safety Authority Evira advised against serving raw beetroot in institutional canteens.

The food court at a shopping mall is a potential transfer point for pathogenic microbes, but to date, this environment has not been the subject of detailed molecular microbiological study. We used a combination of culture-based and culture-independent approaches to investigate the types and numbers of bacteria present on food court tables, and on a food court cleaning cloth. Bacteria were found at 102–105 c.f.u./m2 on food court tables and 1010 c.f.u./m2 on the cleaning cloth. Tag-pyrosequencing of amplified 16S rRNA genes revealed that the dominant bacterial types on the cleaning cloth were genera known to include pathogenic species (Stenotrophomonas, Aeromonas), and that these genera were also evident at lower levels on table surfaces, suggesting possible cross-contamination. The evidence suggests a public health threat is posed by bacteria in the food court, and that this may be due to cross-contamination between cleaning equipment and table surfaces.

Rotavirus is a common viral cause of severe diarrhoea. For the underlying cause of rotavirus seasonality, the meteorological factor has been suspected, whereas quantitative correlation between seasonality and meteorological factor has not been fully investigated. In this study, we investigated the correlation of temporal patterns of the isolation rate of rotavirus with meteorological condition (temperature, relative humidity, rainfall) in Kolkata, India. We used time-series analysis combined with spectral analysis and least squares method. A 1-year cycle explained underlying variations of rotavirus and meteorological data. The 1-year cycle for rotavirus data was correlated with an opposite phase to that for meteorological data. Relatively high temperature could be associated with a low value of isolation rate of rotavirus in the monsoon season. Quantifying a correlation of rotavirus infections with meteorological conditions might prove useful in predicting rotavirus epidemics and health services could plan accordingly.

Cryptosporidium is a zoonotic protozoan parasite with public health importance worldwide. The objectives of this study were to (1) conduct a meta-analysis of published literature for oocyst shedding and diarrhoea outcomes, and (2) develop recommendations for standardization of experimental dose–response studies. Results showed that for the outcome of oocyst shedding in faeces, the covariates ‘experimental species’, ‘immunosuppression’, ‘oocyst dose’ and ‘oocyst dose’ × ‘age’ were all significant (P ⩽ 0·05). This study suggests that exposing mice, piglets, or ruminants, and using immunosuppressed experimental hosts, is more likely to result in oocyst shedding. For the outcome of diarrhoea in experimentally infected animal species, the key covariates ‘experimental species’, ‘age’ and ‘immunosuppression’ were significant (P ⩽ 0·2). Therefore, based on the results of this meta-analysis, these variables should be carefully reported and considered when designing experimental dose–response studies. Additionally, detection of possible publication bias highlights the need to publish additional studies that convey statistically non-significant as well as significant results in the future.

This study investigates neighbourhood variation in rates of pneumococcal bacteraemia and community-level factors associated with neighbourhood heterogeneity in disease risk. We analysed data from 1416 adult and paediatric cases of pneumococcal bacteraemia collected during 2005–2008 from a population-based hospital surveillance network in metropolitan Philadelphia. Cases were geocoded using residential address to measure disease incidence by neighbourhood and identify potential neighbourhood-level risk factors. Overall incidence of pneumococcal bacteraemia was 36·8 cases/100 000 population and varied significantly (0–67·8 cases/100 000 population) in 281 neighbourhoods. Increased disease incidence was associated with higher population density [incidence rate ratio (IRR) 1·10/10 000 people per mile2, 95% confidence interval (CI) 1·0–1·19], higher percent black population (per 10% increase) (IRR 1·07, 95% CI 1·04–1·09), population aged ⩽5 years (IRR 3·49, CI 1·8–5·18) and population aged ⩾65 years (IRR 1·19, CI 1·00–1·38). After adjusting for these characteristics, there was no significant difference in neighbourhood disease rates. This study demonstrates substantial small-area variation in pneumococcal bacteraemia risk that appears to be explained by neighbourhood sociodemographic characteristics. Identifying neighbourhoods with increased disease risk may provide valuable information to optimize implementation of prevention strategies.

We investigated the genetic structure of 99 isolates of serotype 23F Streptococcus pneumoniae from children with acute respiratory infections collected over two periods from 1997 to 2006, and 2010. All isolates were susceptible to vancomycin and amoxicillin–clavulanic acid; 97 were resistant to erythromycin, 95 of which carried the ermB gene and two carried both mefA/E and ermB genes. Multidrug resistance to three or more classes of antibiotics was exhibited by 90 isolates. Sequence types ST342 and ST81 were the most frequent in 1997–2006 and 2010, respectively. All CC81 isolates were non-susceptible to β-lactam antibiotics and had higher minimum inhibitory concentration values for penicillin than other clone complexes and sequence types. The increased β-lactam antibiotic resistance may have resulted from the replacement of multidrug-resistant clones related to ST81. Long-term studies on S. pneumoniae serotype 23F, especially the ST81 clone, should be conducted to better understand the epidemiological picture of this pathogen in China.

In September 2006, the 7-valent pneumococcal conjugate vaccine (PCV7) was added to the UK immunization programme. We aimed to evaluate the impact of PCV7 on the incidence of all-cause community-acquired pneumonia (CAP) in children. A prospective survey was undertaken in 2008–2009 at 11 hospitals in North East England of children aged 0–16 years with radiologically confirmed pneumonia. Data were compared to those from a similar survey undertaken in the same hospitals in 2001–2002. A total of 542 children were enrolled, of which 74% were aged <5 years. PCV7 uptake was 90·7%. The incidence of pneumonia was 11·8/10 000 [95% confidence interval (CI) 10·9–12·9], and the hospitalization rate was 9·9/10 000 (95% CI 9·0–10·9). Compared to 2001, there was a 19% (95% CI 8–29) reduction in the rate of CAP in those aged <5 years, and in those <2 years a 33·1% (95% CI 20–45) reduction in the incidence of CAP and 38·1% (95% CI 24–50) reduction in hospitalization rates. However, for those unvaccinated aged ⩾5 years, there was no difference in the incidence of CAP and hospitalization rate between both surveys. Since 2001, the overall reduction in incidence was 17·7% (95% CI 8–26) and for hospitalization 18·5% (95% CI 8–28). For the <5 years age group there was a lower incidence of CAP in PCV7-vaccinated children (25·2/10 000, 95% CI 22·6–28·2) than in those that were not vaccinated (37·4/10 000, 95% CI 29·2–47·1). In conclusion, PCV7 has reduced both incidence and rate of hospitalization of pneumonia in children, particularly in the <2 years age group.

Despite infection control measures, an important increase in the extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae incidence density occurred in our hospital from 2006 onwards. This study, focusing on the 2005–2007 period, was performed in an attempt to explain this increase. ESBLs were characterized, isolates were typed by ERIC2-PCR, and sequence type (ST) of clustered isolates was determined. Temporal-spatial relationships of patients were analysed to assess possible cross-contamination. Of the 74 ESBL-producing isolates, 30 (40%) were detected at admission, 53 (71·5%) produced CTX-M enzymes, 40 displayed unique ERIC2-PCR profiles and 34 were assigned into six clusters: ST16 (n = 21), ST101, ST48, ST35, ST13, and ST436. Relationships were identified in 22 of the 34 patients harbouring clustered isolates. This study highlights the complex epidemiology of ESBL-producing K. pneumoniae in the mid-2000s with potential cross-contamination for only 30% of the 74 patients in our hospital, and the emergence of clones that are currently spreading worldwide.

A review of the annual prevalence of Pseudomonas aeruginosa at a regional hospital in Taiwan revealed a significant increase in the incidence of extensive drug-resistant P. aeruginosa (XDRPA) from 2·1% in 2003 to 5·8% in 2007. The first XDRPA isolate was recovered in 2001 from the emergency ward. The widespread dissemination of XDRPA isolates to more than 10 other wards was discovered the following year. Six pulsotypes of 67 XDRPA isolates from 2006 onwards were identified and 91% were a single strain, suggesting the existence of a hidden outbreak. Prior to the recognition of the outbreak, the majority of cases were not considered to be healthcare-associated infections until molecular evidence was provided. A cohort measure was launched by the infection control practitioners that effectively controlled the outbreak. Patients with XDRPA were mostly referred from neighbouring long-term care facilities, which may have been the reservoir of the XDRPA clone.

Children with sickle cell anaemia (SCA) might carry hospital-associated bacterial lineages due to frequent hospital stays and antibiotic treatments. In this study we compared Staphylococcus aureus from SCA patients (n = 73) and healthy children (n = 143) in a cross-sectional study in Gabon. S. aureus carriage did not differ between children with SCA (n = 34, 46·6%) and controls matched for age, residence and sex (n = 67, 46·9%). Both groups shared similar S. aureus genotypes. This finding points towards a transmission of S. aureus between both groups in the community. We conclude that resistance rates from population-based studies with healthy participants could therefore also be used to guide treatment and prophylaxis of endogenous infections in children with SCA despite a different selection pressure.

We undertook a national paediatric seroprevalence survey of measles, mumps and rubella (MMR) in Singapore to assess the impact of the national childhood immunization programme against these three diseases after introduction of the trivalent MMR vaccine in 1990. The survey involved 1200 residual sera of Singapore residents aged 1–17 years collected from two hospitals between 2008 and 2010. The overall prevalence of antibodies against measles, mumps and rubella was 83·1% [95% confidence interval (CI) 80·9–85·1], 71·8% (95% CI 69·1–74·2) and 88·5% (95% CI 86·6–90·2), respectively. For all three diseases, the lowest prevalence was in children aged 1 year (47·8–62·3%). The seroprevalence of the vaccinated children declined over time. The national MMR immunization programme is effective in raising the herd immunity of the childhood population, although certain age groups are more susceptible to infection, in particular, those who are not eligible for vaccination at age <15 months.

In order to estimate influenza-associated excess mortality in southern Brazil, we applied Serfling regression models to monthly mortality data from 1980 to 2008 for pneumonia/influenza- and respiratory/circulatory-coded deaths for all ages and for those aged ⩾60 years. According to viral data, 73·5% of influenza viruses were detected between April and August in southern Brazil. There was no clear influenza season for northern Brazil. In southern Brazil, influenza-associated excess mortality was 1·4/100 000 for all ages and 9·2/100 000 person-years for persons aged ⩾60 years using underlying pneumonia/influenza-coded deaths and 10·0/100 000 for all ages and 86·6/100 000 person-years for persons aged ⩾60 years using underlying respiratory/circulatory-coded deaths. Influenza-associated excess mortality rates for southern Brazil are similar to those published for other countries. Our data support the need for continued influenza surveillance to guide vaccination campaigns to age groups most affected by this virus in Brazil.

We examined the uptake of HIV testing in black Africans living in England before the introduction of national testing guidelines. Analyses were conducted using data from an anonymous self-completed questionnaire linked to oral fluid samples to establish HIV status in black Africans attending community venues in England in 2004. Of 946 participants, 44% had ever been tested for HIV and 29% had been tested in the previous 24 months. Of those with undiagnosed HIV, 45% had previously had a negative HIV test. Almost a third of people tested in the UK had been at general practice. Uptake of HIV testing was not associated with perceived risk of HIV. These findings highlight the need for the implementation of national HIV testing guidelines in the UK, including the promotion of testing in general practice. Regular testing in black Africans living in the UK should be promoted regardless of their HIV test history.