In New Zealand Campylobacter infection rates have increased steadily since 1980, reaching a peak in 2003 (396/100 000 population). Compared to other nations, disease rates are unfavourably high (e.g. Australia 117/100 000 population, UK 85/100 000 population, USA 13/100 000 population). This ecological study investigated spatial variations in Campylobacter infection rates across New Zealand's Territorial Local Authorities (TLAs, n=73) for the period 1997–2005. Applying multiple linear regression, we examined whether geographical factors such as socio-demographic characteristics, climate, land use, water and the food environment were associated with local differences in the occurrence of Campylobacter infection rates. The results suggested significant variations in campylobacteriosis across TLAs (average annual rates ranging from 97 to 526/100 000 population), with higher rates in the South Island. Disease rates were associated with lower socio-economic deprivation (P<0·01), the proportion of the population aged 25–44 years (P<0·01) and fresh food outlet density (P<0·76). The results underline the role of area-level characteristics in explaining the spatial distribution of campylobacteriosis in New Zealand. In particular, the findings draw attention to the relatively unexplored role of fresh food outlets as a potential risk factor for increased Campylobacter notifications.

The epidemiology of human campylobacteriosis is complex but in recent years understanding of this disease has advanced considerably. Despite being a major public health concern in many countries, the presence of multiple hosts, genotypes and transmission pathways has made it difficult to identify and quantify the determinants of human infection and disease. This has delayed the development of successful intervention programmes for this disease in many countries including New Zealand, a country with a comparatively high, yet until recently poorly understood, rate of notified disease. This study investigated the epidemiology of Campylobacter jejuni at the genotype-level over a 3-year period between 2005 and 2008 using multilocus sequence typing. By combining epidemiological surveillance and population genetics, a dominant, internationally rare strain of C. jejuni (ST474) was identified, and most human cases (65·7%) were found to be caused by only seven different genotypes. Source association of genotypes was used to identify risk factors at the genotype-level through multivariable logistic regression and a spatial model. Poultry-associated cases were more likely to be found in urban areas compared to rural areas. In particular young children in rural areas had a higher risk of infection with ruminant strains than their urban counterparts. These findings provide important information for the implementation of pathway-specific control strategies.

A total of 969 isolates of Campylobacter jejuni originating in the Preston, Lancashire postcode district over a 3-year period were characterized using multi-locus sequence typing. Recently developed statistical methods and a genetic model were used to investigate temporal, spatial, spatio-temporal and genetic variation in human C. jejuni infections. The analysis of the data showed statistically significant seasonal variation, spatial clustering, small-scale spatio-temporal clustering and spatio-temporal interaction in the overall pattern of incidence, and spatial segregation in cases classified according to their most likely species-of-origin.

A case-control study comprising 1315 Campylobacter jejuni cases, 121 Campylobacter coli cases and 3409 frequency-matched controls was conducted in The Netherlands in 2002–2003. Risk factors for both C. jejuni and C. coli enteritis were consumption of undercooked meat and barbecued meat, ownership of cats and use of proton pump inhibitors. Consumption of chicken was a predominant risk factor for C. jejuni enteritis, but many additional risk factors were identified. Unique risk factors for C. coli infections were consumption of game and tripe, and swimming. Contact with farm animals and persons with gastroenteritis were predominant risk factors for C. jejuni enteritis in young children (0–4 years). Important risk factors for the elderly (⩾60 years) were eating in a restaurant, use of proton pump inhibitors and having a chronic intestinal illness. Consumption of chicken in spring, steak tartare in autumn and winter and barbecued meat in rural areas showed strong associations with C. jejuni infections. This study illustrates that important differences in risk factors exist for different Campylobacter spp. and these may differ dependent on age, season or degree of urbanization.

The aim of the study was to develop a procedure to remove spatial trends in irregularly spaced data, with trends partly due to regional differences. Median polish is often used on regularly spaced (lattice) data where column and row medians are removed. For irregularly spaced data a low-resolution map of the spatial locations is often used where data locations are assigned to the nearest lattice node followed by median polish. In this study regional polish was developed. The inverse distance weighted median was calculated based on observations from locations in the neighbourhood of the actual observation. The regional polish residual is obtained as the difference between the observed value and the weighted median. The regional polish procedure was applied to Salmonella Dublin data showing strong regional trends. Estimation of the range of influence between cattle herds with positive S. Dublin herd status was considerably improved with a stable parameter estimate and reduced standard error.

Isolation rates in Canada of Salmonella enterica serovar Typhi increased from 0·29 to 0·55 isolations/100 000 population during 2000–2006. Although no ciprofloxacin resistance was detected, nalidixic acid resistance increased from 41% to 80%. Multidrug-resistant S. Typhi represented 18% of the strains tested. Pulsed-field gel electrophoresis (PFGE) analysis of 222 isolates resulted in 91 distinct patterns clustering into four major genetic similarity groups. The five most frequently occurring PFGE patterns accounted for 46% of the isolates. Drug-resistant isolates predominantly occurred in one PFGE similarity group. There were 39 phage types identified in 826 isolates analysed with 60% described by five phage types; 134 were untypable. The phage types associated with multidrug resistance were phage types 53, B1, D1, E1, E9, G3 and M1. Improved integration of epidemiological and laboratory case data will facilitate the protection of public health in Canada during an era of increasing travel and globalization.

A cross-sectional study into risk factors for Salmonella was undertaken using data gathered from 252 fattening turkey flocks in the UK. The data was derived from the EU baseline survey conducted during 2006 and 2007, in addition to a voluntary questionnaire. Multivariate logistic regression models identified significant risk factors for Salmonella spp. and Salmonella Typhimurium. A decreased risk of Salmonella spp. infection was associated with a history of intestinal illness in the sampled flock (OR 0·17), the use of wood shavings as litter (OR 0·21), use of disinfectant in the cleaning process (OR 0·25), incineration of dead birds on farm (OR 0·29), seasonal production (OR 0·31), farm staff also working with cattle (OR 0·31), and the presence of pigs on neighbouring farms (OR 0·38). The risk of isolating Salmonella spp. varied according to the company from which the poults were sourced. A reduced risk of S. Typhimurium infection was associated with the use of wax blocks to control rodents (OR 0·09), using mains water (OR 0·19) and having a Salmonella test programme (OR 0·23). An increased risk of S. Typhimurium infection was associated with storage of items around the turkey house (OR 5·20), evidence of mice (OR 4·71) and a soil surface surrounding the turkey house (OR 2·70). This study therefore identifies a number of important practical measures which can be implemented by farmers and veterinarians within the turkey industry to assist in the control of salmonellosis at the farm level.

In outbreaks of foodborne disease associated with retail outlets, the outlet often closes as a precaution before the specific food vehicle has been identified. Suspect food vehicles may be named as part of general control measures. A conventional case-control study cannot be performed because both cases and potential controls are likely to be aware of the hypothesis and therefore potentially biased. Modern sales recording systems in many food retail outlets may provide a basis for constructing a virtual cohort and allow a statistical inference to be made about various possible vehicles of infection. In 2007, an outbreak of E. coli O157 infection in Paisley, Scotland, was linked to cooked meat from a supermarket delicatessen using descriptive epidemiology. Construction of a virtual cohort allowed a relative risk and confidence interval to be estimated which supported the hypothesis of cooked beef topside being the vehicle of infection. This novel method could be valuable in the investigation of future outbreaks.

In late 2002, health professionals from the ministries of health and academia of Jordan, the Palestinian Authority and Israel formed the Middle East Consortium on Infectious Disease Surveillance (MECIDS) to facilitate trans-border cooperation in response to infectious disease outbreaks. The first mission of MECIDS was to establish a regional, laboratory-based surveillance network on foodborne diseases. The development of harmonized methodologies and laboratory capacities, the establishment of a common platform of communication, data sharing and analysis and coordination of intervention steps when needed were agreed upon. Each of the three parties selected the microbiological laboratories that would form the network of sentinel laboratories and cover the different districts of each country and also designated one laboratory as the National Reference Laboratory (NRL). Data analysis units have been established to manage the data and serve as a central point of contact in each country. The MECIDS also selected a regional data analysis unit, the Cooperative Monitoring Centre (CMC) located in Amman, Jordan, and established a mechanism for sharing data from the national systems. Joint training courses were held on interventional epidemiology and laboratory technologies. Data collection started in July 2005 with surveillance of salmonellosis as the first target. This network of collaboration and communication established in an area of continuous dispute represents an important step towards assessing the burden of foodborne diseases in the region and is expected to be fundamental for coordination of public health interventions and prevention strategies.

To better understand the epidemiology of colonization of vancomycin-resistant enterococci (VRE), we performed an 8-year retrospective study of all hospitalized patients with recurrent VRE colonization after they were documented as being clear of VRE and compared the primary colonization isolates and recolonization isolates by pulsed-field gel electrophoresis and Tn1546 typing. Review of the medical records of all patients showed that of the 15 patients with recurrent colonization, six continued to be hospitalized on the same floor. Five were discharged home and then readmitted. Four were moved to another floor. Patients who remained on the same floor were recolonized with a strain that was indistinguishable from the original colonizing strain. Patients who were moved or were discharged had de novo VRE colonization with strains distinct from the original colonizing strain.

Norovirus is a major cause of infectious intestinal disease, and a substantial prevalence of asymptomatic infection has been reported. We describe the prevalence, seasonality and characteristics of asymptomatic norovirus infection in England. Healthy individuals were recruited at random from the general population during the Study of Infectious Intestinal Disease (1993–1996). Norovirus was identified using real-time RT–PCR. The age-adjusted prevalence of asymptomatic norovirus infection was 12%; prevalence was highest in children aged <5 years and showed wintertime seasonality. More work is needed to understand whether asymptomatic infections are important for norovirus transmission leading to sporadic illness and outbreaks.

The clinical significance of different genetic subtypes or assemblages of Giardia lamblia is uncertain. Cases of giardiasis in south-west London between 1999 and 2005 were studied, comparing molecular-typing results with clinical and epidemiological findings from routine surveillance. We identified 819 cases, of whom 389 returned surveillance questionnaires. A subset of 267 faecal samples was submitted for typing by sequencing of the triose phosphate isomerase (tpi) and ribosomal RNA genes, and/or a separate duplex PCR of the tpi gene. Typing was successful in 199 (75%) samples by at least one of the molecular methods. Assemblage A accounted for 48 (24%) samples and Assemblage B for 145 (73%); six (3%) were mixed. Both assemblages had similar seasonality, age distribution and association with travel. Clinical features were available for 59 successfully typed cases: both assemblages caused similar illness, but Assemblage A was significantly more frequently associated with fever than Assemblage B.

The disease pyramid of under-ascertainment for surveillance of acute gastrointestinal illness (AGI) in New Zealand has been estimated using 2005–2007 data on notifiable diseases, a community telephone survey, and a survey of diagnostic laboratories. For each notified case of AGI there were an estimated 222 cases in the community, about 49 of which visited a general practitioner. Faecal samples were requested from about 15 of these cases, and 13 samples were provided. Of the faecal samples, pathogens were detected in about three cases. These ratios are similar to those reported in other developed countries, and provide baseline measurements of the AGI burden in the New Zealand community.

As the 2009 H1N1 influenza pandemic (H1N1) has shown, public health decision-makers may have to predict the subsequent course and severity of a pandemic. We developed an agent-based simulation model and used data from the state of Georgia to explore the influence of viral mutation and seasonal effects on the course of an influenza pandemic. We showed that when a pandemic begins in April certain conditions can lead to a second wave in autumn (e.g. the degree of seasonality exceeding 0·30, or the daily rate of immunity loss exceeding 1% per day). Moreover, certain combinations of seasonality and mutation variables reproduced three-wave epidemic curves. Our results may offer insights to public health officials on how to predict the subsequent course of an epidemic or pandemic based on early and emerging viral and epidemic characteristics and what data may be important to gather.

Puumala virus (PUUV) causes mild haemorrhagic fever with renal syndrome, a rodent-borne zoonosis. To evaluate the disease burden of PUUV infections in Finland, we analysed data reported by laboratories to the National Infectious Disease Registry during 1995–2008 and compared these with data from other national registries (death, 1998–2007; hospital discharge, 1996–2007; occupational diseases, 1995–2006). A total of 22 681 cases were reported (average annual incidence 31/100 000 population); 85% were in persons aged 20–64 years and 62% were males. There was an increasing trend in incidence, and the rates varied widely by season and region. We observed 13 deaths attributable to PUUV infection (case-fatality proportion 0·08%). Of all cases, 9599 (52%) were hospitalized. Only 590 cases (3%) were registered as occupational disease, of which most were related to farming and forestry. The wide seasonal and geographical variation is probably related to rodent density and human behaviour.

We constructed a syndromic surveillance system to collect directly information on daily health conditions directly from local residents via the internet [web-based daily questionnaire for health surveillance system (WDQH SS)]. This paper considers the feasibility of the WDQH SS and its ability to detect epidemics. A verification study revealed that our system was an effective surveillance system. We then applied an improved WDQH SS as a measure against public health concerns at the G8 Hokkaido Toyako Summit meeting in 2008. While in operation at the Summit, our system reported a fever alert that was consistent with a herpangina epidemic. The highly mobile WDQH SS described in this study has three main advantages: the earlier detection of epidemics, compared to other surveillance systems; the ability to collect data even on weekends and holidays; and a rapid system set-up that can be completed within 3 days.

Infection by Listeria monocytogenes in pregnant women may result in fetal loss or invasive disease in the newborn. We examined listeriosis cases reported through the U.S. Listeria Initiative during 2004–2007. Cases were classified as pregnancy-associated if illness occurred in a pregnant woman or an infant aged <28 days. Of 758 reported Listeria cases, 128 (16·9%) were pregnancy-associated. Maternal infection resulted in four neonatal deaths and 26 (20·3%) fetal losses. Invasive illnesses in newborns (n=85) were meningitis (32·9%) and sepsis (36·5%). Pregnant women with Listeria were more likely to report Hispanic ethnicity (52·8% vs. 25·6%, respectively; OR 3·3 95% CI 2·2–4·8) than mothers giving live birth in the USA during 2005 and were more likely to report consumption of Mexican-style cheese (OR 2·6, 95% CI 1·6–4·2) than were non-pregnant patients with Listeria infection. Pregnant woman comprised a considerable proportion of reported listeriosis cases. Further declines in pregnancy-associated listeriosis will require education about avoiding high-risk foods, and continued regulatory and industry efforts to decrease Listeria in foods.

Injection site infections in injecting drug users (IDUs) are associated with serious morbidity and healthcare costs. Factors associated with symptoms of these were examined through annual (2006–2008) unlinked-anonymous survey of IDUs in England, Wales and Northern Ireland. Overall 36% (1863/5209) self-reported having a symptom with no trend over time (35% 2006, 37% 2007, 34% 2008). Symptoms were less common in the North East of England; increased with years injecting; and were higher in women, those recently homeless, those recently using a needle exchange, and those injecting both opiates and stimulants. Of those injecting during the previous 4 weeks (n=3733) symptoms were associated with: injecting daily; injecting ⩾10 times a day; injecting into hands, groin, or legs; sharing filters; and reusing water to flush syringes. Symptoms of injection site infections are common in IDUs. Better-targeted preventive interventions are needed, and continued surveillance should assist with assessing the impact of new initiatives.