We propose an analytical and conceptual framework for a systematic and comprehensive assessment of disease seasonality to detect changes and to quantify and compare temporal patterns. To demonstrate the proposed technique, we examined seasonal patterns of six enterically transmitted reportable diseases (EDs) in Massachusetts collected over a 10-year period (1992–2001). We quantified the timing and intensity of seasonal peaks of ED incidence and examined the synchronization in timing of these peaks with respect to ambient temperature. All EDs, except hepatitis A, exhibited well-defined seasonal patterns which clustered into two groups. The peak in daily incidence of Campylobacter and Salmonella closely followed the peak in ambient temperature with the lag of 2–14 days. Cryptosporidium, Shigella, and Giardia exhibited significant delays relative to the peak in temperature (~40 days, P<0·02). The proposed approach provides a detailed quantification of seasonality that enabled us to detect significant differences in the seasonal peaks of enteric infections which would have been lost in an analysis using monthly or weekly cumulative information. This highly relevant to disease surveillance approach can be used to generate and test hypotheses related to disease seasonality and potential routes of transmission with respect to environmental factors.

Non-typhoid Salmonella infections may present as severe gastroenteritis necessitating hospitalization and some patients become septic with bacteraemia. We hypothesized that the seasonal variation of non-typhoid Salmonella occurrence in humans diminishes with increased severity of infection. We examined the seasonal variation of non-typhoid Salmonella infections in three patient groups with differing severity of infection: outpatients treated for gastroenteritis (n=1490); in-patients treated for gastroenteritis (n=492); and in-patients treated for bacteraemia (n=113). The study was population-based and included all non-typhoid Salmonella patients in a Danish county from 1994 to 2003. A periodic regression model was used to compute the peak-to-trough ratio for the three patient groups. The peak-to-trough ratios were 4·3 [95% confidence interval (CI) 3·6–5·0] for outpatients with gastroenteritis, 3·2 (95% CI 2·4–4·2) for in-patients with gastroenteritis, and 1·6 (95% CI 1·0–2·8) for in-patients with bacteraemia. We conclude that the role of seasonal variation diminishes with increased severity of non-typhoid Salmonella infection.

Nine different arboviruses are known to be transmitted by, or associated with, mosquitoes in Europe, and several (West Nile, Sindbis and Tahyna viruses) are reported to cause outbreaks of human disease. Although there have been no reported human cases in Great Britain (GB), there have been no published in-depth serological surveys for evidence of human infection. This paper investigates the ecological and entomological factors that could influence or restrict transmission of these viruses in GB, suggesting that in addition to West Nile virus, Sindbis and Tahyna viruses could exist in enzootic cycles, and that certain ecological factors could facilitate transmission to humans. However, the level of transmission is likely to be lower than in endemic foci elsewhere in Europe due to key ecological differences related to spatial and temporal dynamics of putative mosquito vectors and presence of key reservoir hosts. Knowledge of the potential GB-specific disease ecology can aid assessments of risk from mosquito-borne arboviruses.

Hepatitis B virus (HBV) infection is a worldwide health problem. The aim of the present study was not only to determine the prevalence of HBsAg in children of HBV-infected parents but also to identify all HBSAg-positive family members to protect as many children, in the present and future, as possible. The study was carried out with the participation of 2113 family members (1205 children, 453 mothers, and 455 fathers) at Sivas SSK Hospital, Turkey. They were screened for HBV markers using standard enzyme immunoassay between September 2001 and March 2005. The prevalence of any HBV markers and HBsAg among family members of index cases was 50·5% and 30·5% respectively. HBsAg carrier rate was higher among fathers (61%) than mothers (47%), (P<0·05). The children of mother index cases had higher rates of HBsAg compared with the children of father index cases (P<0·01). Our results suggest that intra-familial childhood horizontal transmission (especially mother-to-child) is important for HBV transmission in the Turkish community, and highlights the need for screening of adult siblings and mothers of adult HBsAg carriers in addition to their spouses and children.

From 1996 to 2003, four 12-month population-based surveys were performed in FoodNet sites to determine the burden of diarrhoeal disease in the population. Acute diarrhoeal illness (ADI) was defined as [ges ]3 loose stools in 24 hours with impairment of daily activities or duration of diarrhoea >1 day. A total of 52840 interviews were completed. The overall weighted prevalence of ADI in the previous month was 5·1% (95% CI±0·3%), corresponding to 0·6 episodes of ADI per person per year. The average monthly prevalence of ADI was similar in each of the four survey cycles (range 4·5–5·2%). Rates of ADI were highest in those age <5 years. Of those with ADI, 33·8% (95% CI±2·7%) reported vomiting, 19·5% (95% CI±2·1%) visited a medical provider, and 7·8% (95% CI±1·4%) took antibiotics. Rates of ADI were remarkably consistent over time, and demonstrate the substantial burden placed on the health-care system.

The epidemic of type 2 diabetes in the United States prompted us to explore the association between diabetes and tuberculosis (TB) on the South Texas–Mexico border, in a large population of mostly non-hospitalized TB patients. We examined 6 years of retrospective data from all TB patients (n=5049) in South Texas and northeastern Mexico and found diabetes self-reported by 27·8% of Texan and 17·8% of Mexican TB patients, significantly exceeding national self-reported diabetes rates for both countries. Diabetes comorbidity substantially exceeded that of HIV/AIDS. Patients with TB and diabetes were older, more likely to have haemoptysis, pulmonary cavitations, be smear positive at diagnosis, and remain positive at the end of the first (Texas) or second (Mexico) month of treatment. The impact of type 2 diabetes on TB is underappreciated, and in the light of its epidemic status in many countries, it should be actively considered by TB control programmes, particularly in older patients.

On 3 February 2004, the Vermont Department of Health received reports of acute gastroenteritis in persons who had recently visited a swimming facility. A retrospective cohort study was conducted among persons attending the facility between 30 January and 2 February. Fifty-three of 189 (28%) persons interviewed developed vomiting or diarrhoea within 72 h after visiting the facility. Five specimens tested positive for norovirus and three specimen sequences were identical. Entering the smaller of the two pools at the facility was significantly associated with illness (RR 5·67, 95% CI 1·5–22·0, P=0·012). The investigation identified several maintenance system failures: chlorine equipment failure, poorly trained operators, inadequate maintenance checks, failure to alert management, and insufficient record keeping. This study demonstrates the vulnerability of recreational water to norovirus contamination, even in the absence of any obvious vomiting or faecal accident. Our findings also suggest that norovirus is not as resistant to chlorine as previously reported in experimental studies. Appropriate regulations and enforcement, with adequate staff training, are necessary to ensure recreational water safety.

Within the European Union (EU), documenting the burden of invasive pneumococcal disease (IPD) in infants and children is important for coordinating effective pneumococcal immunization policies. Our objective was to document the burden of IPD in countries of the EU plus Switzerland and Norway. European affiliates of Wyeth Vaccines made available recent epidemiological data on IPD from local disease surveillance programmes, including unpublished sources. Recent literature and websites were also searched to provide as wide a representation as possible. This included OVID and abstracts from a number of international meetings, dating from the year 2000. The reported rates of paediatric IPD per 100 000 (age) ranged from a low of 1·7 (<2 years) to 4·2 (2–15 years) in Sweden to a high of 93·5 to 174 (<2 years) to 56·2 (<5 years) in Spain. The percentage of circulating serotypes causing IPD that are covered by 7-valent pneumococcal conjugate vaccine (PCV) IPD serotype coverage ranged from 60% to 80% for European children aged <2 years. Under reporting, differences in reporting methods, antibiotic prescribing and disparities in blood-culturing practices may explain the differences in reported disease incidence. Because of the excellent clinical efficacy of the PCV against IPD, national pneumococcal vaccination programmes in Europe have the potential to prevent much morbidity and mortality.

We investigated the comparative seroepidemiology of varicella zoster virus (VZV) in pregnant women of two ethnic groups, white British and Bangladeshi, living in an inner city area of London, United Kingdom. Women aged 16–45 years were recruited from antenatal clinics of the Royal London Hospital in the Borough of Tower Hamlets. Complete data were obtained from 275 white British and 765 Bangladeshi women. VZV antibody prevalence was 93·1% (95% CI 89·4–95·8) and 86·0% (95% CI 83·3–88·4) respectively. Women who were born in Bangladesh and lived there at least until the age of 15 years had the lowest odds of being immune (OR 0·37, 95% CI 0·22–0·63). This implies they will have an increased risk of varicella during pregnancy. Women arriving in the United Kingdom in adulthood should be screened routinely during pregnancy and vaccination offered postpartum if they are susceptible.

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.

Using isolates from reported cases of Escherichia coli O157 from Alberta, Canada in 2002, we applied randomization tests to determine if cases associated with an outbreak or statistical space–time cluster had more similar pulsed-field gel electrophoresis patterns, based on Dice coefficients, than expected by chance alone. Within each outbreak and space–time cluster, we assessed the mean, median, 25th percentile, 75th percentile, standard deviation, coefficient of variation, and interquartile range of the Dice coefficients of each pairwise comparison among the isolates. To assess the statistical significance of measures of location (e.g. mean) and variation (e.g. standard deviation) we created randomization distributions using all isolates or only isolates from sporadic cases. We determined that randomization tests are an appropriate tool for evaluating the similarity among isolates from cases that have been linked epidemiologically or statistically. We found little difference between using all cases or only sporadic cases when creating our randomization distributions.

Salmonella Braenderup is an uncommon serotype in the United States. In July 2004, a multistate outbreak of Salmonella Braenderup diarrhoeal infections occurred, with 125 clinical isolates identified. To investigate, we conducted a case-control study, enrolling 32 cases and 63 matched controls. Cheese, lettuce and tomato eaten at restaurants all appeared to be associated with illness. To further define specific exposures, we conducted a second study and asked managers of restaurants patronized by patients and controls about cheese, lettuce and tomato varieties used in dishes their patrons reported consuming. This information was obtained for 27 cases and 29 controls. Roma tomatoes were the only exposure significantly associated with illness (odds ratio 4·3, 95% confidence interval 1·2–15·9). Roma tomatoes from two restaurants were traced back to a single tomato packing house. The methods used in this field investigation to define specific exposures may be useful for other foodborne outbreaks.

In three successive years, we visited petting farms (n=132), care farms (n=91), and farmyard campsites (n=84), respectively, and completed a standard questionnaire with the objective of determining the hygienic status of these farms and describing hygiene measures implemented to reduce the risk of transmission of zoonotic agents from the animals to humans. For at least 85% of the farms, the overall impression of hygiene was recorded as good. However, more attention must be paid to: informing visitors on hygiene and handwashing, provision of handwashing facilities, and a footwear cleaning facility. Examination of samples of freshly voided faeces resulted in the detection of Shiga toxin-producing Escherichia coli O157 and/or Salmonella spp. and/or Campylobacter spp. at almost two-thirds (64·9%) of the petting farms, and around half of the care farms (56·0%) and farmyard campsites (45·2%). These data reinforce the need for control measures for both public and private farms to reduce human exposure to livestock faeces and thus the risk of transmission of zoonotic diseases. Public awareness of the risk associated with handling animals or faecal material should be increased.

Enterohaemorrhagic Escherichia coli O157 (O157) is infectious to humans, particularly children, at very low doses and causes not only haemorrhagic colitis but also other serious symptoms. To investigate an association between intestinal bacterial flora and resistance to such infections, we screened faecal samples for the presence of enteric bacteria that are able to suppress the growth of O157. Samples from 303 individuals, 35 children (aged [les ]6 years) and 268 adults (aged 20–59 years), were examined. Colonies with different appearances on sorbitol MacConkey agar medium were screened for the production of bacteriocins inhibitory for O157 in an overlay agar plate assay. O157-inhibiting strains were isolated from 52 individuals. The prevalence of these bacteria tended to rise with age, and was significantly higher among 40- to 59-year-old adults (23/101, 22·8%) than among children (3/35, 8·6%; P<0·05). To test the hypothesis that these bacteriocin-producing strains contribute to resistance against O157 in human adults, we examined faecal samples of 25 healthy O157 carriers. Inhibitory bacteria were more prevalent among the latter (9/25, 36·0%) than among age-matched subjects who did not carry O157 (49/268, 18·3%). It appears, therefore, that inhibitory bacteria in the human gut may play a role in inhibiting propagation of O157 and/or suppressing expression of virulence factors by this pathogen.

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.

In August–September 2004, a cryptosporidiosis outbreak affected >250 persons who visited a California waterpark. Employees and patrons of the waterpark were affected, and three employees and 16 patrons admitted to going into recreational water while ill with diarrhoea. The median illness onset date for waterpark employees was 8 days earlier than that for patrons. A case-control study determined that getting water in one's mouth on the waterpark's waterslides was associated with illness (adjusted odds ratio 7·4, 95% confidence interval 1·7–32·2). Laboratory studies identified Cryptosporidium oocysts in sand and backwash from the waterslides' filter, and environmental investigations uncovered inadequate water-quality record keeping and a design flaw in one of the filtration systems. Occurring more than a decade after the first reported outbreaks of cryptosporidiosis in swimming pools, this outbreak demonstrates that messages about healthy swimming practices have not been adopted by pool operators and the public.

Rotaviruses were detected by enzyme-linked immunosorbent assay (ELISA) in 92 out of 374 faecal samples collected between November 2003 and October 2004 at the Markaz Tebbi Koudakan Hospital, Tehran, Iran, from children aged 6 months to 5 years. Analysis of clinical and disease severity data showed a significant association between rotavirus infection and diarrhoea, vomiting and severe dehydration. Ninety-two samples (64 rotavirus ELISA-positive and 28 ELISA-negative samples) were sent to the Enteric Virus Unit, Virus Reference Department, Centre for Infection, Health Protection Agency, UK for rotavirus characterization by G-typing, P-typing and subgrouping (SG) using reverse transcriptase (RT)–PCR, semi-nested PCR and sequencing methods. In this study, both common and uncommon rotavirus genotypes were detected. The most prevalent types were G1P[8], SGII (59·2%) followed by G9P[8] SGII (15·5%) which has not been previously reported from Iran. Unusual genotypes G1P[10] SGI (2·8%) and G12P[8] SGII (1·4%) and strains derived from reassortment between common co-circulating genotypes such as G1P[4] SGII represented 5·6% of strains. Mixed infections with combinations of G1+G4P[8] SGII and G1+G9P[8] SGII were also found. This contrasts with previous reports from Iran in which a small number of common rotavirus strains (G1 and G4) were found. This study highlights the need for continued surveillance and characterization of rotaviruses to take account of the rapid evolution and introduction of novel rotaviruses into the human population.

The incidence of invasive meningococcal disease (IMD) in Germany in 2003 was estimated by the two-source capture–recapture method. As a unique personal identifier was unavailable, cases with IMD tested at the National Reference Centre for Meningococci (NRZM) were matched with cases reported to the Robert Koch Institute (RKI) through the statutory surveillance system by using demographic and disease-specific variables common to both datasets. The estimated overall incidence was 1·1 IMD cases/100 000 inhabitants, with a sensitivity of ascertainment of 64·8% for NRZM and 89·4% for RKI. Case-fatality rate was estimated at 8·8%. Adjustment for heterogeneity of capture according to age, region and serogroup observed in the NRZM (but not RKI) source had minimal effect on the estimated incidence. The IMD incidence estimated by capture–recapture analysis is thus only slightly higher than through statutory surveillance data. As a degree of positive dependence between the systems cannot be ruled out, this estimate may still be an underestimate. However, under ascertainment appears insufficient to explain the low incidence of IMD in Germany compared to other European countries.

A serological survey has been used to investigate the epidemiology of parvovirus B19 infection in England and Wales. A total of 2835 sera representing the complete age range were selected from a convenience collection obtained in 1996 that reflects the general population and screened for parvovirus B19-specific IgG. Antibody prevalence rose nonlinearly with age from 21% in those aged 1–4 years to >75% in adults aged ⩾45 years. Force-of-infection estimates were similar to those previously made in 1991, being highest in those aged <15 years. There was no association between evidence of previous infection and sex or region. Quantitatively strongest antibody responses were found in those aged 15–34 years and IgG levels in females were 28·5% higher than those found in males (P=0·004, 95% CI 8·2–52·6). Applying the upper 95% confidence interval for the force of infection to maternity estimates for England and Wales in 1996, parvovirus infection in pregnancy was estimated to occur on average in up to 1 in every 512 pregnancies each year. This represents 1257 maternal infections, causing up to an estimated 59 fetal deaths and 11 cases of hydrops fetalis annually. An analysis of all available laboratory-confirmed parvovirus infections found a mean of 944 infections per year in women aged 15–44 years highlighting a need for enhanced surveillance of maternal parvovirus B19 infection in England and Wales, including information on both pregnancy and outcome of pregnancy.

In September 2004, an outbreak of community-associated methicillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infections (SSTI) was reported among members of a religious community. We conducted a retrospective cohort study on all 175 community members; performed a nasal carriage survey, and environmental swab testing. We identified 24 MRSA cases (attack rate 14%). In multivariate analysis, sauna use [odds ratio (OR) 19·1, 95% confidence interval (CI) 2·7–206·1] and antimicrobial use within 12 months before infection (OR 11·7, 95% CI 2·9–47·6) were risk factors for infection. MRSA nasal carriage rate was 0·6% (1/174). Nine of 10 clinical isolates and an isolate from an administrative office within the community had the pulsed-field gel electrophoresis type USA300. Targeted hygiene improvement, wound care, and environmental cleaning were implemented. We describe the first reported outbreak of MRSA SSTI in a religious community. Adherence to appropriate personal and environmental hygiene might be critical factors in controlling transmission.