Salmonella is an important cause of human illness. Disease is frequently associated with foodborne transmission, but other routes of exposure are recognized. Identifying sources of disease is essential for prioritizing public health interventions. Numerous case-control studies of sporadic salmonellosis have been published, often using different methodologies and settings. Systematic reviews consist of a formal process for literature review focused on a research question. With the objective of identifying the most important risk factors for salmonellosis, we performed a systematic review of case-control studies and a meta-analysis of obtained results. Thirty-five Salmonella case-control studies were identified. In the meta-analysis, heterogeneity between studies and possible sources of bias were investigated, and pooled odds ratios estimated. Results suggested that travel, predisposing factors, eating raw eggs, and eating in restaurants were the most important risk factors for salmonellosis. Sub-analyses by serotype were performed when enough studies were available.

Campylobacter spp. is a widespread and important cause of human illness worldwide. Disease is frequently associated with foodborne transmission, but other routes of exposure, such as direct contact with live animals and person-to-person transmission, are also recognized. Identifying the most important sources of human disease is essential for prioritizing food safety interventions and setting public health goals. Numerous case-control studies of sporadic infections of campylobacteriosis have been published. These studies investigated a variety of potential risk factors for disease, often using different methodologies and settings. Systematic reviews (SRs) consist of a formal process for literature review focused on a specific research question, and include the identification of relevant literature, quality assessment of relevant studies, summarization or statistical analysis of data, and conclusions. With the objective of identifying the most important risk factors for human sporadic campylobacteriosis, we performed a SR of case-control studies of human sporadic cases and a meta-analysis of the obtained results. A combined SR focusing on Salmonella and Campylobacter studies was performed and the results analysed separately. From 1295 identified references, 131 passed the relevance screening, 73 passed the quality assessment stage, and data was extracted from 72 studies. Of these, 38 focused on campylobacteriosis. Information on exposures of cases and controls, and estimated odds ratios for investigated risk factors were collected and analysed. In the meta-analysis, heterogeneity between the studies and possible sources of bias were investigated, and pooled odds ratios for identified risk factors were estimated. Results suggest that travelling abroad, eating undercooked chicken, environmental sources, and direct contact with farm animals were significant risk factors for campylobacteriosis. Sub-analyses by geographical region, age group, and study period were performed, and differences were discussed.

Human salmonellosis cases, particularly those caused by Salmonella Enteritidis, have been closely linked to egg consumption. This epidemiological survey was conducted to determine the baseline Salmonella prevalence and identify the risk factors for Salmonella prevalence in laying-hen farms in Japan. Caecal excrement samples and dust samples were obtained from 400 flocks in 338 laying-hen farms. Salmonella was identified in 20·7% of the farms and 19·5% of the flocks. The prevalence of Salmonella was significantly higher in flocks reared in windowless houses than in those reared in open houses. In addition, the risk of Salmonella presence was significantly higher when the windowless house farms implemented induced moulting or in-line egg processing. Efforts to reduce human salmonellosis in Japan should continue to focus on the establishment of control measures in laying-hen farms, especially those with windowless houses implementing induced moulting and equipped with in-line egg processing.

Japanese weather data for areas that produced Campylobacter spp.-positive chicken products were compared with those for areas producing negative samples. Regarding samples produced during the period of rising temperature (spring and summer), the mean weekly air temperatures for Campylobacter-positive samples were higher than those for negative samples for the period of the week in which the samples were purchased (18·7°C vs. 13·1°C, P=0·006) to a 12-week lag (12 weeks before purchasing samples; 7·9°C vs. 3·4°C, P=0·009). Significant differences in weekly mean minimum humidity and sunshine duration per day were also observed for 1- and 2-week lag periods. We postulated that the high air temperature, high humidity and short duration of sunshine for the chicken-rearing period increased Campylobacter colonization in chickens during the period of rising temperature. Consequently, the number of Campylobacter-contaminated chicken products on the market in Japan may fluctuate because of the climatic conditions to which reared chickens are exposed.

The food service sector continues to be the most common setting for reported foodborne disease outbreaks in England and Wales. Using restaurant-associated foodborne outbreaks reported in England and Wales from 1992 to 2009, cuisine-specific risk factors were examined. Of 677 restaurant outbreaks, there were 11 795 people affected, 491 hospitalizations, and seven deaths; and Chinese, Indian, British and Italian cuisines were the most commonly implicated (26%, 16%, 13% and 10%, respectively). Salmonella spp. accounted for most outbreaks of all cuisine types, and particularly Chinese (76%, 133/175) and Italian (55%, 38/69). Poultry meat was the most frequently implicated food vehicle in outbreaks associated with Indian (30%), Chinese (21%), and British (18%) cuisines while for Italian cuisine, desserts and cakes were more frequently implicated (33%). Rice dishes were also a common outbreak food vehicle in those restaurants serving Chinese (22%) and Indian (16%) cuisine. Cross-contamination was the biggest contributory factor associated with Chinese (46%), British (33%) and Indian (30%) cuisines whereas inadequate cooking (38%) and use of raw shell eggs in lightly cooked or uncooked food (35%) were more often associated with Italian cuisine. Over the surveillance period, the proportion of Salmonella Enteritidis PT4 outbreaks in restaurants serving Chinese cuisine significantly decreased (P<0·0001) and this was mirrored by an increase in S. Enteritidis non-PT4 outbreaks (P<0·0001). Despite this change in proportion, contributory factors such as cross-contamination have continued to cause outbreaks throughout the 18 years. The results show that by stratifying the risks associated with restaurants by cuisine type, specific evidence of food control failures can be used to target foodborne illness reduction strategies.

On 26 November 2010, an outbreak of scombroid fish poisoning occurred in the French Armed Forces in Dakar, Senegal. This chemical intoxication, due to high histamine concentration in fish, is often mistaken for an allergic reaction. A case-control study was undertaken including the 71 cases and 78 randomly selected controls among lunch attendees. The usual symptoms for scombroid fish poisoning were observed in cases, i.e. flushing (85·9%), headache (83·1%), rapid/weak pulse (59·1%) and diarrhoea (47·9%). Symptoms occurred from within a few minutes to up to 3 h following the meal. Most patients quickly recovered with antihistamine and/or symptomatic treatment. Tuna was the only food item positively associated with illness (odds ratio 36·3, 95% confidence interval 6·3–210·0), with the risk of illness increasing with the quantity of fish consumed. No bacterial contamination was found in leftover food, but histamine concentration in tuna was found to be 4900 mg/kg, almost 50-fold higher than the concentration allowed by European regulations. This report is unique because of the large size of the case series – to our knowledge, the largest event of scombroid fish poisoning ever reported – and the chemical and bacteriological analyses results obtained on leftover food.

Group A rotaviruses infect humans and a variety of animals. In July 2006 a rare rotavirus strain with G8P[14] specificity was identified in the stool samples of two adult patients with diarrheoa, who lived in the same geographical area in Denmark. Nucleotide sequences of the VP7, VP4, VP6, and NSP4 genes of the identified strains were identical. Phylogenetic analyses showed that both Danish G8P[14] strains clustered with rotaviruses of animal, mainly, bovine and caprine, origin. The high genetic relatedness to animal rotaviruses and the atypical epidemiological features suggest that these human G8P[14] strains were acquired through direct zoonotic transmission events.

The aim of this study was to determine the nationwide prevalence of smear-positive tuberculosis (TB) in Bangladesh. A multi-stage cluster survey of a random sample of persons aged ⩾15 years was included in 40 clusters (20 urban, 20 rural). Two sputum samples were collected from study participants and tested initially by fluorescence microscopy and confirmed by the Ziehl–Neelsen method. The crude and adjusted prevalence rates and 95% confidence intervals (CIs) were calculated using standard methods. A total of 33 new smear-positive TB cases were detected among 52 098 individuals who participated in the study. The average participation rate was over 80%. The overall crude prevalence of new smear-positive TB in persons aged ⩾15 years was estimated as 63·3/100 000 (95% CI 43·6–88·9) and the adjusted prevalence was 79·4/100 000 (95% CI 47·1–133·8). TB prevalence was higher in males (n=24) and in rural areas (n=20). The prevalence was highest in the 55–64 years age group (201/100 000) and lowest in 15–24 years age group (43·0/100 000). The prevalence was higher in persons with no education (138·6/100 000, 95% CI 78·4–245·0). The overall prevalence of smear-positive TB was significantly lower than the prevalence estimate of the previous nationwide survey in Bangladesh in 1987–1988 (870/100 000).

We screened tuberculosis (TB) contacts as an outbreak investigation with tuberculin skin test (TST) and interferon-gamma release assay (IGRA). We evaluated adverse events and TB incidence in all persons screened after rifampicin (RFP) prophylaxis, and specifically assessed the new TB cases in relation to initial TST and IGRA results. The 180 contacts were divided into four groups: TST+/IGRA+ (n=101), TST+/IGRA− (n=22), TST−/IGRA+ (n=16), and TST–/IGRA– (n=41). RFP treatment (4 months) was prescribed only to the TST+/IGRA+ group. Of 87 contacts who initiated prophylaxis, adverse events occurred in 21 contacts (24·1%) including hepatotoxicity (11·5%), flu-like syndrome (5·7%), and thrombocytopenia (3·4%). TB developed in two TST+/IGRA+ subjects after completion of prophylaxis, including one multidrug-resistant (MDR)-TB case during 21·8 months of follow-up. Adverse events were frequent, and development of TB including MDR-TB occurred after RFP prophylaxis.

In New Zealand, bovine tuberculosis (bTB) is present in domestic cattle and deer herds primarily as the result of on-going disease transmission from the primary wildlife host, the brushtail possum (Trichosurus vulpecula). However, bTB is also present in other introduced free-ranging mammalian species. Between 1996 and 2007, we conducted a series of studies to determine whether poison control of possum populations would have any effect on the prevalence of Mycobacterium bovis infection in sympatric feral pigs (Sus scrofa). We compared trends in the prevalence of bTB infection in feral pigs in six study areas: possum numbers were reduced in three areas, but not in the other three, effectively providing a thrice-replicated before-after-control-intervention design. Before possum control, the overall prevalence of culture-confirmed M. bovis infection in feral pigs was 16·7–94·4%, depending on area. Infection prevalence varied little between genders but did vary with age, increasing during the first 2–3 years of life but then declining in older pigs. In the areas in which possum control was applied, M. bovis prevalence in feral pigs fell to near zero within 2–3 years, provided control was applied successfully at the whole-landscape scale. In contrast, prevalence changed much less or not at all in the areas with no possum control. We conclude that feral pigs in New Zealand acquire M. bovis infection mainly by inter-species transmission from possums, but then rarely pass the disease on to other pigs and are end hosts. This is in contrast to the purported role of pigs as bTB maintenance hosts in other countries, and we suggest the difference in host status may reflect differences in the relative importance of the oral route of infection in different environments. Despite harbouring M. bovis infection for a number of years, pigs in New Zealand do not sustain bTB independently, but are good sentinels for disease prevalence in possum populations.

In Scotland, an estimated 1% of the population is infected with hepatitis C virus (HCV). There is ethnic diversity in Scotland, with a large Pakistani sub-population. Our aim was to investigate the prevalence of HCV in an immigrant Pakistani population and effectiveness of an outreach testing intervention. We arranged a series of HCV awareness meetings at the mosques and Pakistani Women's centre in the city of Dundee. Thereafter short-term outreach HCV testing clinics were set up in the same venues. Venous blood samples were obtained and tested for HCV IgG and HbsAg. A short questionnaire was also completed. In total, 177 individuals volunteered for testing, out of an estimated 250 who attended meetings and a total Pakistani population in Dundee of 1723. Of those tested 170 were Scottish Pakistanis (159 first generation, 11 second generation). There were 145 (85·2%) men. The mean age was 45·11 (±s.d. 16·7) years. Seven (4·1%) individuals in the cohort were anti-HCV positive. Five (2·9%) were found to have HCV RNA by PCR. Only one patient had chronic hepatitis B infection. All patients with positive results were seen in the liver clinic for consideration of treatment. We have demonstrated that immigrant Pakistanis retain a higher prevalence of HCV compared to the population of their adopted country. Outreach targeted testing in this group can be achieved using religious and cultural gatherings, with only modest investment in staff time.

In developed countries the majority of hepatitis C virus (HCV) infections occur in injecting drug users (IDUs) with prevalence in IDUs often high, but with wide geographical differences within countries. Estimates of local prevalence are needed for planning services for IDUs, but it is not practical to conduct HCV seroprevalence surveys in all areas. In this study survey data from IDUs attending specialist services were collected in 52/149 sites in England between 2006 and 2008. Spatially correlated random-effects models were used to estimate HCV prevalence for all sites, using auxiliary data to aid prediction. Estimates ranged from 14% to 82%, with larger cities, London and the North West having the highest HCV prevalence. The methods used generated robust estimates for each area, with a well-identified spatial pattern that improved predictions. Such models may be of use in other areas of study where surveillance data are sparse.

Injecting drug users (IDUs) account for most new HCV infections. The objectives of this study were: to estimate the force of infection for hepatitis C virus in IDUs within the interval-censoring framework and to determine the impact of risk factors such as frequency of injection, drug injected, sharing of syringes and time of first injection on the time to HCV infection. We used data from the Amsterdam Cohort Study collected in The Netherlands and focused on those individuals who were HCV negative upon entry into the study. Based on the results, the force of infection was found to vary with time of first injection. The risk of infection was higher in the first 3 years of an IDU's career, implying estimates based on single cross-sectional studies could be biased. Frequency of injection and type of drug injected were found to be highly significant predictors, whereas sharing syringes was not.

Surveillance of acute hepatitis B in England is necessary to estimate incidence, determine routes of transmission and inform public health actions. Here we describe an automated process to extract information on testing for markers of hepatitis B infection in English sentinel laboratories between 2002 and 2008. The resulting data were used to identify individuals with acute infections, describe their characteristics and estimate the incidence of infection. Two-thirds of acute infections were in males. Heterosexual exposure and injecting drug use were the main risks reported. Annual incidence was estimated at 1·3/100 000 person-years overall (1·7 and 0·6 for males and females, respectively) and declined each year. Automated extraction of hepatitis B markers, including quantitative results where available, can help to classify HBV status more accurately for surveillance. HBV incidence in England is at its lowest level in recent years.

The Poisson model can be applied to the count of events occurring within a specific time period. The main feature of the Poisson model is the assumption that the mean and variance of the count data are equal. However, this equal mean-variance relationship rarely occurs in observational data. In most cases, the observed variance is larger than the assumed variance, which is called overdispersion. Further, when the observed data involve excessive zero counts, the problem of overdispersion results in underestimating the variance of the estimated parameter, and thus produces a misleading conclusion. We illustrated the use of four models for overdispersed count data that may be attributed to excessive zeros. These are Poisson, negative binomial, zero-inflated Poisson and zero-inflated negative binomial models. The example data in this article deal with the number of incidents involving human papillomavirus infection. The four models resulted in differing statistical inferences. The Poisson model, which is widely used in epidemiology research, underestimated the standard errors and overstated the significance of some covariates.

There is currently no information regarding the genetic diversity of HPV-6 variants circulating in South Africa. The aim of this study was to determine the HPV-6 variants affecting patients with recurrent respiratory papillomatosis, to determine whether mutations correlate with disease severity and identify molecular determinants of virulence with prognostic relevance. HPV-6 variants were identified based on genome changes within the 712-991 bp region encompassing the non-coding region (URR) of the genome, with variations in length resulting from insertions and duplications, and the 453-bp gene encoding the E6 protein. Based on manual comparison of sequence data from the URR, the isolates were identified as HPV-6a and HPV-6vc variants. Three novel HPV-6 variants were identified: one based on a mutation in the E6 region; two based on changes in the URR including a unique substitution detected in three isolates and an insertion and 170-bp duplication in the URR genome in one patient, who had clinical features of severe disease.

A pandemic influenza A(H1N1) 2009 outbreak in a summer school affected 117/276 (42%) students. Residential social contact was associated with risk of infection, and there was no evidence for transmission associated with the classroom setting. Although the summer school had new admissions each week, which provided susceptible students the outbreak was controlled using routine infection control measures (isolation of cases, basic hygiene measures and avoidance of particularly high-risk social events) and prompt treatment of cases. This was in the absence of chemoprophylaxis or vaccination and without altering the basic educational activities of the school. Modelling of the outbreak allowed estimation of the impact of interventions on transmission. These models and follow-up surveillance supported the effectiveness of routine infection control measures to stop the spread of influenza even in this high-risk setting for transmission.

The 7-valent pneumococcal conjugate vaccine (PCV7) is reported to decrease the incidence of community-acquired pneumonia (CAP) in children. To determine the annual incidence of CAP before the introduction of PCV7, we counted the number of children hospitalized with CAP between 2008 and 2009 in Chiba City, Japan. We investigated serotype and multilocus sequence typing (MLST) for Streptococcus pneumoniae isolates in CAP cases. The annual incidence of hospitalized CAP in children aged <5 years was 17·6 episodes/1000 child-years. In 626 episodes, S. pneumoniae was dominant in 14·7% and 0·8% of sputum and blood samples, respectively. The most common serotypes were 6B, 23F and 19F. The coverage rates of PCV7 were 66·7% and 80% in sputum samples and blood samples, respectively. MLST analysis revealed 37 sequence types. Furthermore, 54·1% of the sputum isolates and 40% of the blood isolate were related to international multidrug-resistant clones.

We retrospectively analysed the epidemiological data of all hand, foot, and mouth disease (HFMD) cases from the largest paediatric infectious diseases centre in Shanghai between 2007 and 2010. A total of 28 058 outpatients were diagnosed with HFMD, of which 3948 (14·07%) were hospitalized, 730 (2·60%) had complications with neurological disorders and pulmonary oedema/haemorrhage, and 11 (0·04%) died. The peak season was the summer months. Boys were more affected than girls. Since 2008, the major population group affected has shifted from native Shanghainese children attending preschool to migrant children and younger children cared for at home. Children aged 1–4 years constituted 82·27% of cases. EV-A71 was tested in clinical samples taken from severe cases in 2009 and 2010, and from most inpatients in 2010. EV-A71 was positive in 99·17% and 86·31% of severe cases, respectively in 2009 and 2010. All 12 cases with pulmonary oedema or haemorrhage were infected with EV-A71. Ten (90·90%) of 11 fatal cases were attributable to EV-A71 infection. In 2010, EV-A71-positive cases accounted for 54·12% of inpatients. The dominant circulation of EV-A71 led to the outbreak of HFMD and occurrence of severe and fatal cases.

The introduction and the widespread use of the varicella vaccine in Taiwan has led to a 75–80% decrease in the incidence of varicella in children. However the vaccine's long-term impact on the incidence of herpes zoster (HZ) has attracted attention. By controlling gender, underlying diseases, and age effects, a Poisson regression was applied on the 2000–2008 chart records of 240 000 randomly selected residents who enrolled in the Universal National Health Insurance. The results show that, as the vaccine coverage in children increases, the incidence of varicella decreases. However, the incidence of HZ increased even before the implementation of the free varicella vaccination programme in 2004, particularly in females. The increase in the incidence of HZ cannot be entirely and directly attributed to the widespread vaccination of children. Continuous monitoring is needed to understand the secular trends in HZ before and after varicella vaccination in Taiwan and in other countries.