A ten-fold increase in Salmonella Typhimurium DT104 cases in The Netherlands during September–November 2005 prompted an outbreak investigation. A population-based matched case-control study included 56 cases and 100 controls. Risk factors for infection were consumption of a pre-processed raw beef product (odds ratio 4·2, 95% confidence interval 1·5–12·0) and of food from mobile caterers (odds ratio 4·9, 95% confidence interval 1·1–22·1). Bacterial molecular typing established a link with another DT104 outbreak in Denmark caused by beef from a third European country. The incriminated beef was traced in The Netherlands and sampling yielded DT104 of the outbreak-associated molecular type. We concluded that this outbreak was caused by imported contaminated beef. Consumers should be informed about presence of raw meat in pre-processed food products. Optimal utilization of international networks and testing and traceability of foodstuffs has the potential to prevent foodborne infections.

We report an outbreak with Salmonella Typhimurium DT104 resistant to six different antibiotic classes. The outbreak occurred in Denmark in July/August 2005 and was traced to a single restaurant. In addition to patient interviews, an important tool in the investigation of this outbreak was comparison by multi-locus variable number of tandem repeat analysis (MLVA) typing of patient strains with strains from the food surveillance system. This showed that the source of the outbreak was imported beef served as carpaccio. Carpaccio, thinly sliced raw fillet of beef, has not previously been associated with outbreaks, but should be considered a high-risk food item. This outbreak was one of two in different European Union (EU) countries traced back to beef from one company in a third EU country. This underscores the importance of efficient international Salmonella surveillance and food-safety control systems enabling timely interventions within the EU.

Varicella vaccine was licensed in Canada in 1998, and a publicly funded vaccination programme introduced in the province of Alberta in 2001. In theory the vaccination programme might increase the burden of disease from shingles, making it important to develop baseline data against which future comparisons can be made. The study's aim was to describe the epidemiology of non-fatal cases of shingles for which publicly funded health services were utilized for the period 1986–2002. Shingles cases were identified from the records of Alberta's universal, publicly funded health-care insurance system for 1986–2002. The earliest dated health service utilizations for ICD-9-CM codes of 053 or ICD-10-CA codes of B02 were classified as incident. Diagnostic codes at least 180 days after the first were classified as recurrent episodes. Denominators for rates were estimated using mid-year population estimates from the Alberta Health Care Insurance Plan Registry. Annual age- and sex-specific rates were estimated. We explored the pattern of rates for sex, age and year effects and their interactions. Shingles rates increased between 1986 and 2002. There was a sex effect and evidence of an age–sex interaction. Females had higher rates than males at every age; however, the difference between females and males was greatest for the 50–54 years age group and declined for older age groups. The increased rate of shingles in Alberta began before varicella vaccine was licensed or publicly funded in Alberta, and thus cannot be attributed to vaccination.

We report attack rates and contact-related predictors among community contacts of severe acute respiratory syndrome (SARS) cases from the 2003 Toronto-area outbreak. Community contact data was extracted from public health records for single, well-defined exposures to a SARS case. In total, 8662 community-acquired exposures resulted in 61 probable cases; a crude attack rate of 0·70% [95% confidence interval (CI) 0·54–0·90]. Persons aged 55–69 years were at higher risk of acquiring SARS (1·14%) than those either younger (0·60%) or older (0·70%). In multivariable analysis exposures for at least 30 min at a distance of ⩽1 m increased the likelihood of becoming a SARS case 20·4-fold (95% CI 11·8–35·1). Risk related to duration of illness in the source case at time of exposure was greatest for illness duration of 7–10 days (rate ratio 3·4, 95% CI 1·9–6·1). Longer and closer proximity exposures incurred the highest rate of disease. Separate measures of time and distance from source cases should be added to minimum datasets for the assessment of interventions for SARS and other emerging diseases.

We describe the development of the HIV epidemic in Karonga District, Malawi over 22 years using data from population surveys and community samples. These data are used to estimate the trend in HIV prevalence, incidence and need for antiretroviral treatment (ART) using a simple mathematical model. HIV prevalence rose quickly in the late 1980s and early 1990s, stabilizing at around 12% in the mid-1990s. Estimated annual HIV incidence rose quickly, peaking in the early 1990s at 2·2% among males and 3·1% among females, and then levelled off at 1·3% among males and 1·1% among females by the late 1990s. Assuming a 2-year eligibility period, both our model and the UNAIDS models predicted 2·1% of adults were in need of ART in 2005. This prediction was sensitive to the assumed eligibility period, ranging from 1·6% to 2·6% if the eligibility period was instead assumed to be 1·5 or 2·5 years, respectively.

Studies of antenatal women form the predominant source of data on HIV-1 prevalence in Africa. Identifying factors associated with prevalent HIV is important in targeting diagnostic services and care. Between November 1997 and January 2000, 14 110 postnatal women from Harare, Zimbabwe were tested by ELISAs reactive to both HIV-1 and HIV-2; a subset of positive samples was confirmed with assays specific for HIV-1 and HIV-2. Baseline characteristics were elicited and modelled to identify risk factors for prevalent HIV infection. HIV-1 and HIV-2 prevalences were 32·0% (95% CI 31·2–32·8) and 1·3% (95% CI 1·1–1·5), respectively; 4% of HIV-1-positive and 99% of HIV-2-positive women were co-infected. HIV-1 prevalence increased from 0% among 14-year-olds to >45% among women aged 29–31 years, then fell to <20% among those aged >40 years. In multivariate analyses, prevalence increased with parity, was lower in married women than in single women, divorcees and widows, and higher in women with the lowest incomes and those professing no religion. Adjusted HIV-1 prevalence increased during 1998 and decreased during 1999. Age modified the effects of parity, home ownership and parental education. Among older women, prevalence was greater for women who were not homeowners. Among younger women, prevalence increased with parity and low parental education. None of these factors distinguished women co-infected with HIV-2 from those infected with HIV-1 alone. Prevalent HIV-1 infection is associated with financial insecurity and weak psychosocial support. The ZVITAMBO study apparently spanned the peak of the HIV-1 epidemic among reproductive women in Harare.

The aim of our study is to describe the prevalence of the different HPV types in women with pre-neoplastic lesions of the cervix in Greece. Cervical scrapes from 841 women were obtained for both cytological evaluation and analysis for the presence of HPV DNA. PCR was performed on specimens from these 841 women. The Pap test results were normal or showed benign cellular changes in 45·8% of the women, atypical squamous cells of undeterminated significance (ASCUS) in 23·2%, low-grade squamous intra-epithelial lesion (LSIL) in 27·9% and high-grade squamous intra-epithelial lesion (HSIL) in 3·1%. HPV DNA was demonstrated in 23·6% of cytologically normal women. We detected HPV in 60% of the total samples. Of these, HPV-16 was the most common HPV DNA detected. Interestingly, HPV-58 was inversely correlated with positive cytological findings. A clear pattern of decreasing prevalence of HPV with age was also observed. Our results indicate that HPV infections, especially those with HPV-16, represent a significant public health concern in Greece.

During the 2004–2005 influenza season two independent influenza surveillance systems operated simultaneously in three United States counties. The New Vaccine Surveillance Network (NVSN) prospectively enrolled children hospitalized for respiratory symptoms/fever and tested them using culture and RT–PCR. The Emerging Infections Program (EIP) and a similar clinical-laboratory surveillance system identified hospitalized children who had positive influenza tests obtained as part of their usual medical care. Using data from these systems, we applied capture–recapture analyses to estimate the burden of influenza related-hospitalizations in children aged <5 years. During the 2004–2005 influenza season the influenza-related hospitalization rate estimated by capture–recapture analysis was 8·6/10 000 children aged <5 years. When compared to this estimate, the sensitivity of the prospective surveillance system was 69% and the sensitivity of the clinical-laboratory based system was 39%. In the face of limited resources and an increasing need for influenza surveillance, capture–recapture analysis provides better estimates than either system alone.

Recently the prevalence of hepatitis B virus (HBV) genotypes and the association between these genotypes and the clinical status of HBV-infected patients were recently investigated in the Lebanese population. The aim of the additional study reported here was to determine the current prevalence of hepatitis delta virus (HDV) infection and the range of HDV genotypes in this Lebanese population. Two hundred and fifty-eight HBsAg-positive patients (107 asymptomatic blood donors, 92 with chronic hepatitis, 24 with cirrhosis, 15 with hepatocellular carcinoma, 20 patients on haemodialysis) from ten medical centers in Lebanon were tested for antibody to hepatitis D virus (anti-HDV). Those testing positive were analysed further for HDV-RNA and for genotyping by reverse transcriptase–polymerase chain reaction (RT–PCR) and restriction fragment length polymorphism (RFLP). Three samples (1·2%) were anti-HDV positive and out of these, only one was HDV-RNA positive (0·6%) and was analysed as HDV genotype I. Our results point to a low endemicity of HDV in the Lebanese population which is in sharp contrast to data reported from Lebanon 20 years ago and to the situation in neighbouring Arab and non-Arab countries in the Mediterranean region. HDV genotype I seems to be the predominant genotype in Lebanon and the Middle East.

The complex pathogen–host–vector system of the tick-borne louping-ill virus causes economic losses to sheep and red grouse in upland United Kingdom. This paper examines the spatial distribution, incidence and effect of control measures on louping-ill virus in the Bowland Fells of Lancashire. Seroprevalence in sheep at the beginning of the study varied within the area and was affected significantly by the frequency of acaricide treatment. There was a clear decrease over 5 years in the effective force of infection on farms implementing a vaccination programme, irrespective of acaricide treatment regime, however, only one third of farms apparently eliminated infection. On farms where vaccination did not occur or where vaccination was carried out intermittently, the estimated force of infection was variable or possibly increased. Thus, as befits a complex host–pathogen system, reductions in prevalence were not as dramatic as predicted; we discuss the potential explanations for these observations.

Serum specimens were collected from 25 wild boars in Hiroshima prefecture located in the western region of Japan from November 2004 to February 2005. The sera were tested for antibodies to Japanese encephalitis virus (JEV) by IgM capture and IgG enzyme-linked immunosorbent assays (ELISA), and plaque reduction neutralization test. Seventeen samples (68%) were positive for neutralizing antibody to JEV. All the neutralizing antibody-positive samples were positive for IgG-ELISA. One was also positive for IgM. The results indicate that approximately 70% of the wild boars were positive for anti-JEV antibody, and raises the possibility that wild boars may play a role in the infectious cycle of JEV in this region.

There are an estimated 277 000 cases of campylobacteriosis in Australia each year, most of which are thought to be sporadically acquired. To explore causes for these infections, we conducted a multi-centre case-control study of patients and community controls across five Australian States during 2001–2002. A total of 881 campylobacter cases and 833 controls aged ⩾5 years were recruited into the study. Crude logistic analyses were conducted within various food and non-food exposure groups. A final most parsimonious multivariable logistic regression model was developed and adjusted odds ratios (aOR), 95% confidence intervals (95% CI) were derived together with adjusted population attributable risks (PAR). Consumption of undercooked chicken (aOR 4·7, 95% CI 2·6–8·4) and offal (aOR 2·0, 95% CI 1·0–4·0), ownership of domestic chickens aged <6 months (aOR 12·4, 95% CI 2·6–59·3) and domestic dogs aged <6 months (aOR 2·1, 95% CI 1·1–4·2) were found to be independent risk factors for illness in the final model. The PAR proportions indicate that eating chicken meat, either cooked or undercooked may account for approximately 30% of campylobacter cases that occur each year in Australia. These results justify the continued need for education of consumers and foodhandlers about the risks associated with the handling of raw chicken and the potential for cross-contamination.

Escherichia coli O157 causes a range of illnesses from mild diarrhoea to haemolytic uraemic syndrome (HUS) which carries a mortality rate of 3·7%. Infection is more common in the under-5s. Between 1995 and 2000, 106 outbreaks of E. coli O157 were reported in England and Wales. Recreational water is well documented as a transmission route for infectious diseases worldwide. In the United Kingdom there have been very few reported outbreaks associated with swimming pools due to the relative susceptibility of E. coli O157 to adequate levels of free chlorine. This report describes the investigation of an outbreak associated with a local leisure centre pool and makes recommendations about the safe management of such facilities.

To monitor risk factors for illness, we conducted a case-control study of sporadic Shiga toxin-producing Escherichia coli O157 (STEC O157) infections in 1999–2000. Laboratory-confirmed cases of STEC O157 infection were identified through active laboratory surveillance in all or part of seven states. Patients and age-matched controls were interviewed by telephone using a standard questionnaire. Information was collected on demographics, clinical illness, and exposures to food, water, and animals in the 7 days before the patient's illness onset. During the 12-month study, 283 patients and 534 controls were enrolled. STEC O157 infection was associated with eating pink hamburgers, drinking untreated surface water, and contact with cattle. Eating produce was inversely associated with infection. Direct or indirect contact with cattle waste continues to be a leading identified source of sporadic STEC O157 infections.

Enterotoxigenic F4+ Escherichia coli can colonize the intestine of pigs and cause diarrhoea. Our primary goal was to find a discriminant rule to discriminate between F4+ E. coli shedding profiles as this may reflect differences in the infectiousness of pigs. Our secondary goal was to find a discriminant rule to discriminate between diarrhoeic and non-diarrhoeic pigs. Repeated measurements (bacterial shedding and percentage dry matter of faeces) were taken of 74 weaned pigs that were infected experimentally with F4+ E. coli. These measurements were summarized into two new variables by means of a principal components analysis. Discriminant rules were derived based on these summary variables by fitting a mixture of normal distributions. Finally, the association between the classifications (as derived from the discriminant rules) and the occurrence in the pigs of the F4 receptor, an adhesion site for F4+ E. coli, was studied. We found that only the classification based on bacterial shedding allowed us to distinguish two significantly different groups of pigs (high and low shedders). Presence of the F4 receptor was associated strongly with pigs being high shedders.

Clostridium difficile (C. diff) is a major nosocomial problem. Epidemiological surveillance of the disease can be accomplished by microbiological or administrative data. Microbiological tracking is problematic since it does not always translate into clinical disease, and it is not always available. Tracking by administrative data is attractive, but ICD-9 code accuracy for C. diff is unknown. By using a large administrative database of hospitalized patients with C. diff (by ICD-9 code or cytotoxic assay), this study found that the sensitivity, specificity, positive, and negative predictive values of ICD-9 coding were 71%, 99%, 87%, and 96% respectively (using micro data as the gold standard). When only using symptomatic patients the sensitivity increased to 82% and when only using symptomatic patients whose test results were available at discharge, the sensitivity increased to 88%. C. diff ICD-9 codes closely approximate true C. diff infection, especially in symptomatic patients whose test results are available at the time of discharge, and can therefore be used as a reasonable alternative to microbiological data for tracking purposes.

Blood culture-based diagnosis can only detect a fraction of the total burden of Salmonella enterica subsp. enterica serovar Typhi. The objective of the study was to detect additional typhoid fever cases through serological tests. A total of 1732 prolonged fever episodes were evaluated using three serological tests, Widal, Tubex® and Typhidot-M® in a typhoid fever endemic area of southern China. A case definition which included a positive Widal test (TO⩾80 & TH>A), a positive Tubex® test (⩾4) and a positive Typhidot-M® test, increased the detection of cases by more than twofold from 13 to 28 cases. The case definition has a specificity of 100% and a sensitivity of 39%. Case definitions based on combinations of serological tests can detect additional typhoid fever cases with higher specificity than a single serological test. Improved case detection is essential to understand the true disease burden and can help to boost the power of intervention trials.

The aim of this study was to describe a systematic process of record-linkage, cross-validation, case-ascertainment and capture–recapture analysis to assess the quality of tuberculosis registers and to estimate the completeness of notification of incident tuberculosis cases in The Netherlands in 1998. After record-linkage and cross-validation 1499 tuberculosis patients were identified, of whom 1298 were notified, resulting in an observed under-notification of 13·4%. After adjustment for possible imperfect record-linkage and remaining false-positive hospital cases observed under-notification was 7·3%. Log-linear capture–recapture analysis initially estimated a total number of 2053 (95% CI 1871–2443) tuberculosis cases, resulting in an estimated under-notification of 36·8%. After adjustment for possible imperfect record-linkage and remaining false-positive hospital cases various capture–recapture models estimated under-notification at 13·6%. One of the reasons for the higher than expected estimated under-notification in a country with a well-organized system of tuberculosis control might be that some tuberculosis cases, e.g. extrapulmonary tuberculosis, are managed by clinicians less familiar with notification of infectious diseases. This study demonstrates the possible impact of violation of assumptions underlying capture–recapture analysis, especially the perfect record-linkage, perfect positive predictive value and absent three-way interaction assumptions.