In December 2006 an outbreak of Campylobacter infection occurred in Forth Valley, Scotland, affecting 48 people over a 3-week period. All cases dined at restaurant A. We conducted a cohort study in a party of 30 who ate lunch at restaurant A on 21 December to identify the vehicle of infection. Of 29 respondents, the attack rate in those who ate chicken liver pâté was 86% (6/7) compared to 0% (0/22) for those who did not. Between 1 December and 1.30 p.m. on 21 December the restaurant had used a different method of cooking the pâté. No cases reported dining at the restaurant after this time. The outbreak's duration suggested a continuous source. This is the first continuous source outbreak of Campylobacter documented in Scotland. Chicken liver pâté was the most likely vehicle of infection. This outbreak illustrates the hazards associated with undercooking Campylobacter-contaminated food.

We evaluated magnitude of bacteraemia as a predictor of mortality, comprising all adult patients with a first-time mono-microbial bacteraemia. The number of positive bottles [1 (reference), 2, or 3] in the first positive blood culture (BC) was an index of magnitude of bacteraemia. We used Cox's regression analysis to determine age and comorbidity adjusted risk of mortality at days 0–7, 8–30, and 31–365. Of 6406 patients, 31·1% had BC index 1 (BCI 1), 18·3% BCI 2, and 50·6% BCI 3. BCI 3 patients had increased risk of mortality for days 0–7 (1·30, 95% CI 1·10–1·55) and days 8–30 (1·37, 95% CI 1·12–1·68), but not thereafter. However, in surgical patients mortality increased only beyond day 7 (8–30 days: 2·04, 95% CI 1·25–3·33; 31–365 days: 1·27, 95% CI 0·98–1·65). Thus, high magnitude of bacteraemia predicted mortality during the first month with a shift towards long-term mortality in surgical patients.

Between October and December 2005, 16 cases of wound botulism were notified to the health authorities of North Rhine-Westphalia, Germany. All patients were injecting drug users (IDU) and the epidemiological investigations suggested contaminated injection drugs as the most probable source of infection. Clostridium botulinum was cultivated from clinical samples of six patients and molecular typing revealed that the different isolates were clonally identical. Two samples of heroin, one of them provided by a patient, were examined but C. botulinum could not be isolated. This outbreak demonstrates that IDU are at risk for acquiring wound botulism by injecting contaminated drugs. A greater awareness of this disease is needed by physicians and a close cooperation between public health authorities, street workers, operators of sheltered injecting facilities, and medical centres focusing on IDU is essential to prevent and manage outbreaks in IDU in a timely manner.

Strategies to lessen the impact of pandemic influenza include behavioural modifications of the general public regarding medical care, personal hygiene and protection, and social distancing. We conducted a telephone survey of Beijing residents to evaluate potential behavioural changes in the general public in the event of an influenza pandemic occurring. We used a two-stage Mitofsky–Waksberg telephone survey of Beijing residents aged ⩾15 years. The sample was weighted to reflect the 2000 census. We asked the respondents about their current healthcare-seeking behaviours for influenza-like illness (ILI), protective measures (personal hygiene, social distancing), and compliance with health authorities. We then asked what they would do during a hypothetical pandemic. We interviewed 256 Beijing participants in our study (response rate 56%). The percent of participants consulting a doctor for ILI rose from the current 41% [95% confidence interval (CI) 35–47] to 74% (95% CI 68–79) during a pandemic. Fifty-five percent (95% CI 48–62) of the participants would seek care from a more specialized hospital during a pandemic than currently. More than 90% of the participants reported already practising hand-washing or covering their coughs or sneezes during a non-pandemic period; this percentage changed little under a pandemic scenario. Compared to the current social distancing practices, more people would avoid crowded places (77% vs. 92%, P<0·01), use a mask outside the home (10% vs. 58%, P<0·01), and take time off from work or school (17% vs. 38%, P<0·01) during a pandemic. Moreover, 26% of the participants (95% CI 21–32) would stockpile food or water, and 55% (95% CI 49–61) would stockpile medicines. Some of the behavioural changes reported by Beijing participants might help to alleviate the damage caused by a potential pandemic. However, increased use of medical care at referral hospitals will further strain the healthcare system during a pandemic.

A serological survey was used to investigate the epidemiology of cytomegalovirus (CMV) infection in England and Wales. A total of 5237 sera representing the complete age range were used reflecting the general population. The sera were collected in 1991 and 2002, and screened for CMV-specific IgG by ELISA. Antibody prevalence increased with age from ~15% in those aged 1–4 years to ~80% in those aged ⩾65 years with no association with gender or region. Analysing by common birth cohort demonstrated that between 1991 and 2002 incidence was highest in children born 1985–1989 (1·62% per year, 95% CI 0·86–2·35), lower in older children and younger adults born 1950–1984 (0·75% per year, 95% CI 0·29–1·19) with little evidence of infection in older adults born pre-1950 (0% per year, 95% CI 0–0·64). Application to population and live-birth estimates for England and Wales suggested that between 1991 and 2002, 159 996 (95% CI 67922–278277) CMV infections occurred annually with an annual average of 2133 (95% CI 816–3435) infections affecting pregnant females.

Crimean-Congo haemorrhagic fever (CCHF) is a tick-borne viral zoonosis widely distributed in Africa, Asia and eastern Europe. Reassortment of CCHF genome segments has been shown to occur in nature. We therefore investigated the genetic relationship of southern African isolates using partial sequence data for each RNA segment, S, M and L, and comparing the tree topologies constructed using a neighbour joining method. A total of 21 southern African isolates were studied. The incongruencies which were identified in S, M and L sequence datasets involved group switching implying reassortment for 15 isolates. A higher fatality rate occurred in patients infected with isolates which had apparently acquired M segments from a group in which predominantly Asian strains are usually found. This suggests that reassortment may affect the pathogenicity of the virus.

West Nile virus (WNV) was probably introduced in southern and northern Mexico from the USA in two independent events. Since then, WNV activity has been reported in several Mexican states bordering the USA and the Gulf of Mexico, but disease manifestations seen there in humans and equids are quite different to those observed in the USA. We have analysed WNV seroprevalence in asymptomatic, unvaccinated equids from two Mexican states where no data had been previously recorded. WNV IgG antibodies were detected in 31·6% (91/288) of equine sera from Chiapas and Puebla states (53·3% and 8·0%, respectively). Analysis by plaque reduction neutralization test (PRNT) showed good specificity (99·4%) and sensitivity (84·9%) with the ELISA results. Further analyses to detect antibodies against three different flaviviruses (WNV, St Louis encephalitis virus, Ilheus virus) by haemagglutination inhibition (HI) tests on a subset of 138 samples showed that 53% of the 83 HI-positive samples showed specific reaction to WNV. These data suggest continuous expansion of WNV through Mexico.

Effective infection control measures during norovirus outbreaks are urgently needed in places where vulnerable individuals gather. In the present study, the effect of a number of measures was investigated in daily practice. Forty-nine Dutch nursing homes were monitored prospectively for norovirus outbreaks during two winter seasons. A total of 37 norovirus outbreaks were registered. Control measures were most effective when implemented within 3 days after onset of disease of the first patient. Measures targeted at reduced transmission between persons, via aerosols, and via contaminated surfaces reduced illness in staff and in residents. Reducing illness in staff results in fewer costs for sick leave and substitution of staff and less disruption in the care of residents. The effect of control measures on outbreak duration was limited. This is the first intervention study examining the effect of control measures. Further research is needed to extend and refine the conclusions.

A large outbreak of Salmonella enterica serotype Newport infection occurred in Northern Ireland during September and October 2004. Typing of isolates from patients confirmed that this strain was indistinguishable from that in concurrent outbreaks in regions of England, in Scotland and in the Isle of Man. A total of 130 cases were distributed unequally across local government district areas in Northern Ireland. The epidemic curve suggested a continued exposure over about 4 weeks. A matched case-control study of 23 cases and 39 controls found a statistically significant association with a history of having eaten lettuce in a meal outside the home and being a case (odds ratio 23·7, 95% confidence interval 1·4–404·3). This exposure was reported by 57% of cases. Although over 300 food samples were tested, none yielded any Salmonella spp. Complexity and limited traceability in salad vegetable distribution hindered further investigation of the ultimate source of the outbreak.

We investigated factors associated with persistence of different Salmonella serovars in buildings housing laying hens in Great Britain using survival analysis. A total of 264 incidents of Salmonella detection occurring between July 1998 and August 2007 in 152 houses were recorded. For incidents involving Salmonella Enteritidis (SE), both the rodent score of the house and the type of house were positively associated with persistence. For non-SE serovars, only the type of house was associated with persistence. Persistence of SE in the houses was longest (>15 months) in step-cage and cage-scraper houses when high levels of rodents were present, and lowest in non-cage and cage-belt houses. We estimated that 42% (95% CI 23·3–63·1) of SE incidents may be cleared during the lay period, and this was related to elimination of rodents from the houses. From January 2009, EU legislation will ban the sale of fresh eggs from SE-positive and S. Typhimurium-positive flocks over their remaining lifespan. If infection is eliminated from such flocks, they would cease to represent a public health risk.

Oral fluid is a non-invasive biological sample, which can be returned by post, making it suitable for large-scale epidemiological studies in children. We report our experience of oral fluid collection from 14 373 preschool-aged children in the UK Millennium Cohort Study. Samples were collected by mothers in the home setting following the guidance of trained interviewers, and posted to the laboratory. Samples were received from 11 698 children (81·4%). Children whose mothers were of Black Caribbean ethnicity and who lived in non-English-speaking households were less likely to provide a sample, and those with a maternal history of asthma more likely to provide a sample [adjusted risk ratio (95% CI) 0·85 (0·73–0·98), 0·87 (0·77–0·98) and 1·03 (1·00–1·05) respectively]. Collection of oral fluid samples is feasible and acceptable in large-scale child cohort studies. Formal interpreter support may be required to increase participation rates in surveys that collect biological samples from ethnic minorities.

We compared the prevalence of human and animal methicillin-resistant Staphylococcus aureus (MRSA) at pig farms in The Netherlands, and related this to individual and farm-level characteristics. More than half of the farms investigated (28/50) had MRSA in pigs or stable dust and about one third (15/50) of person(s) were identified as MRSA carriers. Human carriage was found only on farms with MRSA-positive pigs or dust. MRSA strains in human samples were the same spa-type as found in pigs and all were not typable by pulsed-field gel electrophoresis (NT-MRSA). Multivariate analyses showed that risk factors for human MRSA carriage were: working in pig stables (OR 40, 95% CI 8–209) and the presence of sows and finishing pigs (OR 9, 95% CI 3–30). Veterinary sample collectors sampling the pigs showed transient MRSA carriage only during the day of the farm visit. Working in pig stables with MRSA-positive pigs poses a high risk for acquiring MRSA, increasingly so when contact with live pigs is more intensive or long lasting.

An outbreak of haemolytic uraemic syndrome (HUS) among children caused by infection with sorbitol-fermenting enterohaemorrhagic Escherichia coli O157:H− (SF EHEC O157:H−) occurred in Germany in 2002. This pathogen has caused several outbreaks so far, yet its reservoir and routes of transmission remain unknown. SF EHEC O157:H− is easily missed as most laboratory protocols target the more common sorbitol non-fermenting strains. We performed active case-finding, extensive exploratory interviews and a case-control study. Clinical and environmental samples were screened for SF EHEC O157:H− and the isolates were subtyped by pulsed-field gel electrophoresis. We identified 38 case-patients in 11 federal states. Four case-patients died during the acute phase (case-fatality ratio 11%). The case-control study could not identify a single vehicle or source. Further studies are necessary to identify the pathogen's reservoir(s). Stool samples of patients with HUS should be tested with an adequate microbiological set-up to quickly identify SF EHEC O157:H−.

Using data from a cohort study conducted by the Veterinary Laboratories Agency (VLA), evidence of spatial clustering at distances up to 30 km was found for S. Agama and S. Dublin (P values of 0·001) and borderline evidence was found for spatial clustering of S. Typhimurium (P=0·077). The evolution of infection status of study farms over time was modelled using a Markov Chain model with transition probabilities describing changes in status at each of four visits, allowing for the effect of sampling visit. The degree of geographical clustering of infection, having allowed for temporal effects, was assessed by comparing the residual deviance from a model including a measure of recent neighbourhood infection levels with one excluding this variable. The number of cases arising within a defined distance and time period of an index case was higher than expected. This provides evidence for spatial and spatio-temporal clustering, which suggests either a contagious process (e.g. through direct or indirect farm-to-farm transmission) or geographically localized environmental and/or farm factors which increase the risk of infection. The results emphasize the different epidemiology of the three Salmonella serovars investigated.

This study uses social network analysis to investigate potential contact among 214 dog-owning households in a UK community through their utilization of public space during walking. We identified a high level of potential contact between dog-owning households; most households walked their dogs in only a few areas but a small number visited many. Highly connected households were more likely to have multiple dogs, walk their dogs off lead, and own Working, Pastoral or some Terrier types. Similarly, most areas were only visited by a few households but a few were visited by many. Despite identification of subgroups of households and locations, we demonstrated high connectivity between dog-owning households, with minimum path lengths of two ‘steps’ (household–area–household, 74%) or four ‘steps’ (via two areas, 26%).

The high morbidity and mortality of necrotizing fasciitis (NF) supports the need for epidemiological studies to characterize the disease and identify patient factors associated with adverse outcomes. A multi-site medical record review of patients diagnosed with NF was performed (n=80, mortality 15%). Variables collected were hypothesized to have association with adverse outcomes from NF, and multivariable analysis was used to detect any such association in this population. Select factors associated with mortality included evidence of underlying conditions (P=0·002), advanced age (P=0·04), young age (P=0·03), and evidence of sepsis (P=0·006). Select factors associated with amputation included diabetes mellitus (P=0·006), evidence of underlying conditions (P=0·03), and cutaneous gangrene noted on admission (P=0·006). These findings demonstrate the important association of NF and extremes of age with mortality and morbidity and support the value of early suspicion with prompt diagnosis and treatment in order to prevent adverse outcomes since the associated risk factors are not immediately modifiable.

Three different methods were used for estimating the basic reproductive number (R0) from data on 110 outbreaks of highly pathogenic avian influenza (HPAI) subtype H5N1 that occurred in village poultry in Romania, 12 May to 6 June 2006. We assumed a village-level infectious period of 7 days. The methods applied were GIS-based identification of nearest infectious neighbour (based on either Euclidean or road distance), the method of epidemic doubling time, and a susceptible–infectious (SI) modelling approach. In general, the estimated basic reproductive numbers were consistent: 2·14, 1·95, 2·68 and 2·21, respectively. Although the true basic reproductive number in this epidemic is unknown, results suggest that the use of a range of methods might be useful for characterizing epidemics of infectious diseases. Once the basic reproductive number has been estimated, better control strategies and targeted surveillance programmes can be designed.

Despite being widely recognized as a significant public health problem there are surprisingly few contemporary data available on the incidence of pneumonia in the UK. We conducted a general population-based cohort study to determine the incidence of pneumonia in general practice in the United Kingdom. Data were obtained from The Health Improvement Network (THIN) – a computerized, longitudinal, general practice database. Recorded diagnoses of pneumonia between 1991 and 2003 were used to calculate the incidence of pneumonia stratified by year, sex, age group and deprivation score. The overall incidence of pneumonia was 233/100 000 person-years [95% confidence interval (CI) 231–235] and this rate was stable between 1991 and 2003. The incidence of pneumonia was slightly lower in females compared to males [age-adjusted incidence rate ratio (IRR) 0·88, 95% CI 0·86–0·89]. Pneumonia was most common in children aged <4 years and adults aged >65 years. There was an increased incidence of pneumonia with higher levels of socioeconomic disadvantage such that people living in the most deprived areas of the United Kingdom were 28% more likely to get pneumonia than those in the least deprived areas (age- and gender-adjusted IRR 1·28, 95% CI 1·24–1·32). In conclusion, pneumonia is an important public health problem and the incidence of pneumonia is higher in people at the extremes of age, men and people living in socially deprived areas.

In April 2005, an outbreak of Chikungunya fever occurred on the island of Réunion in the Indian Ocean. During winter 2005, six patients developed meningoencephalitis and acute hepatitis due to Chikungunya virus. Our objectives were to determine the incidence and mortality of atypical Chikungunya viral infections and to identify risk factors for severe disease. A hospital-based surveillance system was established to collect data on atypical Chikungunya cases. Case reports, medical records and laboratory results were reviewed and analysed. We defined an atypical case as one in which a patient with laboratory-confirmed Chikungunya virus infection developed symptoms other than fever and arthralgia. We defined a severe atypical case as one which required maintenance of at least one vital function. We recorded 610 atypical cases of Chikungunya fever: 222 were severe cases, 65 affected patients died. Five hundred and forty-six cases had underlying medical conditions (of which 226 suffered from cardiovascular, 147 from neurological and 150 from respiratory disorders). Clinical features that had never been associated with Chikungunya fever were recorded, such as bullous dermatosis, pneumonia, and diabetes mellitus. Hypertension, and underlying respiratory or cardiological conditions were independent risk factors for disease severity. The overall mortality rate was 10·6% and it increased with age. This is the first time that severe cases and deaths due to Chikungunya fever have been documented. The information presented in this article may assist clinicians in identifying the disease, selecting the treatment strategy, and anticipating the course of illness.

This study primarily aimed to estimate the association between influenza vaccination and the occurrence of hospitalization for acute respiratory or cardiovascular diseases, or all-cause death during the influenza season in an elderly population in South Africa. We conducted a nested case-control study using data from a cohort of 45 522 elderly members of a private medical funding organization during the moderate 2004 influenza season. In 1282 (2·8%) subjects the combined outcome occurred and the influenza vaccination rate in controls was 15·4%. After adjustments for measured confounders, vaccination was associated with a statistically significant reduction of 19% (95% confidence interval 3·1–32·9) in the combined outcome. Post-hoc sensitivity analysis of the potential impact of potential healthy user bias showed that confounding, if present, could have caused this finding. Our data were inconclusive regarding the benefits of influenza vaccination in elderly persons in South Africa and given the low vaccine uptake, long-term follow-up is warranted.