Salmonellosis is a global problem caused by the international movement of foods and high incidence in exporting countries. In September 2001, in an outbreak investigation Australia isolated Salmonella Stanley from imported peanuts, which resulted in a wider investigation in Canada, England & Wales and Scotland. Patients infected with Salmonella serotypes known to be isolated from peanuts and reported to surveillance systems were interviewed to determine exposure histories. Tagged image file format (TIFF) images of pulsed-field gel electrophoresis (PFGE) patterns of Salmonella isolates were shared electronically amongst laboratories. Laboratories tested packets of ‘Brand X’ peanuts from various lots and product lines. In total, 97 cases of S. Stanley and 12 cases of S. Newport infection were found. Seventy-three per cent (71/97) of S. Stanley cases were in persons of Asian ethnicity. Twenty-eight per cent of cases recalled eating Brand X peanuts and a further 13% had peanuts in their house in the previous month or had eaten Asian-style peanuts. Laboratories isolated S. Stanley, S. Newport, S. Kottbus, S. Lexington and S. Unnamed from Brand X peanuts. Isolates of S. Stanley from peanuts and human patients were indistinguishable by PFGE. This international outbreak resulted from a product originating from one country affecting several others. Rapid sharing of electronic DNA images was a crucial factor in delineating the outbreak; multinational investigations would benefit from a harmonized approach.

We report the clinical, microbiological, and epidemiological features of an emerging serotype, Shigella boydii 20. We interviewed patients about symptoms, and history of travel and visitors during the week before illness onset. Seventy-five per cent of the 56 patients were Hispanic. During the week before illness onset, 18 (32%) travelled abroad; 17 (94%) had visited Mexico. Eight (21%) out of 38 who had not travelled had foreign visitors. There were eight closely related patterns by PFGE with XbaI. S. boydii 20 may be related to travel to Mexico and Hispanic ethnicity. Prompt epidemiological investigation of clusters of S. boydii 20 infection may help identify specific vehicles and risk factors for infection.

Fourier time-series models were constructed to study regional and national seasonality of human campylobacteriosis in Scotland between 1997 and 2001. Strong seasonality was demonstrated with an annual peak of reported cases in late June to early July. The prominence of this peak varied between regions, which was exemplified for the two major population centres: Lothian, with mixed urban/rural population, had a more prominent peak than Greater Glasgow, which has a predominantly urban population. No significant trend of annual cases of campylobacteriosis was found nationally and Fourier models successfully predicted the seasonal pattern of national and regional cases in 2002. During the period studied, the Fourier model identified >20 bursts of infection (potential outbreaks). Multi-regional bursts were also identified in the summers of 1998 and 2000 – the latter comprising the vast majority of the regions in Scotland, which could suggest a national outbreak.

The drug susceptibility and genes responsible for the drug resistance of Vibrio cholerae O1 isolated in Vietnam in 1995, 2000 and 2002 were studied. The strains isolated in 1995 were resistant to streptomycin and harboured the class I integron which contained the aadA1 gene responsible for streptomycin resistance. The strains isolated in 2000 were devoid of a class I integron but were multiple-drug resistant and harboured SXT constin, with several drug-resistant genes. The genes responsible for streptomycin resistance were strA and strB. The strains isolated in 2002 were sensitive to all drugs examined, and the organisms were devoid of both class I integron and SXT constin. Cholera outbreaks in the three periods examined (1995, 2000 and 2002) were apparently due to different categories of V. cholerae O1.

Cases of gastroenteritis were examined to identify if dietary intake prior to an episode and food-handling and storage practices in the home were risk factors for illness. Cases and controls completed a dietary questionnaire after an event or when well, and questionnaires concerning food-handling, storage and general food-hygiene practices. Comparing cases to themselves when well, subjects were more likely to have eaten cold sliced salami, fried rice and foods cooked elsewhere, and to have had a baby in nappies in the house (OR 1·52–6·24, P[les ]0·01). Cases compared to non-cases were more likely to have bought frozen poultry, have eaten foods cooked elsewhere and to have had a baby in nappies in the house (OR 1·44–2·05, P[les ]0·01). Although food-handling and storage practices are considered important, we were unable to detect an association in this study.

To estimate the magnitude and distribution of self-reported, acute gastrointestinal illness in a Canadian-based population, we conducted a retrospective, cross-sectional telephone survey of approximately 3500 randomly selected residents of the city of Hamilton (Ontario, Canada) from February 2001 to February 2002. The observed monthly prevalence was 10% (95% CI 9·94–10·14) and the incidence rate was 1·3 (95% CI 1·1–1·4) episodes per person-year; this is within the range of estimates from other developed countries. The prevalence was higher in females and in those aged <10 years and 20–24 years. Overall, prevalence peaked in April and October, but a different temporal distribution was observed for those aged <10 years. Although these data were derived from one community, they demonstrate that the epidemiology of acute gastrointestinal illness in a Canadian-based population is similar to that reported for other developed countries.

Discharge information for all Hong Kong government hospitals, which is routinely collected through the Clinical Management System (CMS), was used to assess the relative importance of all causes of diarrhoeal illness and to address the issue of under-diagnosis of rotavirus by linking discharge diagnostic codes with actual laboratory results for one hospital. Of all children less than 5 years of age hospitalized in Hong Kong in the 2-year period July 1997 to June 1999, 12257 (11%) were discharged with a primary diarrhoea diagnosis (74% coded as non-specified, 10·4% as rotavirus, 11% as Salmonella and 5% as other viral or bacterial). Linked laboratory and discharge data for one hospital demonstrated that 15% (n=1522) of all admissions had a primary diarrhoea diagnosis and that 40% of these had a specimen sent for rotavirus testing, of which 37% were positive. However, 46% (67/145) of children with a diagnosis of rotavirus infection had no virology result, and 69% (172/248) of positive rotavirus results were in children with no diagnosis indicating rotavirus infection. Modification of the CMS to routinely combine existing computerized laboratory data with the CMS discharge diagnoses and to develop mechanisms to enhance reliability of discharge diagnosis coding could produce a powerful resource for disease surveillance, auditing and for monitoring the impact of future vaccination and other prevention programmes.

Cytotoxic enterotoxin (Act) is a key virulence factor in the pathogenesis of infections caused by Aeromonas spp. The cytotoxic enterotoxin gene (act) was detected in 32 out of 69 environmental isolates of Aeromonas spp. by hybridization with the act gene probe. To evaluate the pathogenic potential of the act gene probe-positive isolates, 32 act gene probe-positive and 31 randomly selected act gene probe-negative isolates were tested for enterotoxicity in a suckling mice assay (SMA), for haemolytic activity on sheep blood agar plates, for the presence of CAMP-like factors, and for cytotoxicity in a Vero cell line. The act gene probe-positive isolates significantly differed from the toxin gene probe-negative ones with respect to enterotoxicity in the SMA (P=0·009) and haemolytic activity (P=0·005). The CAMP–haemolysin phenotype was significantly associated with the rabbit ileal loop assay (P=0·08), Vero cell assay (P=0·064), and haemolysin production under the microaerophilic conditions (P=0·056) of the act gene probe-positive isolates of Aeromonas spp. These data indicated the role of Act in the pathogenesis of Aeromonas infections and that the enterotoxic potential of Aeromonas spp. could be assessed by simply performing a CAMP–haemolysin assay.

The annual incidence of meningococcal disease (meningitis and septicaemia) in Taiwan was 0·94/105 population in 1953. It then declined to below 0·001 from 1980 to 1987, and re-emerged in 2000 with a rate of 0·07/105 population. In 2001 there was a further increase in incidence (43 cases, 0·19/105). Of 43 isolates of Neisseria meningitidis available for this study, including 41 from patients treated in 2001, three (7·0%) were penicillin insensitive (MIC [ges ]0·12 μg/ml), though all were β-lactamase negative; 16 (37·2%) were resistant to trimethoprim–sulphamethoxazole sulphamethoxazole (MIC [ges ]4/76 μg/ml). Serogrouping and genotype analysis revealed nine domestic clones. None of the 43 patients had any relationship (travel or contact history) with the 2000 or 2001 Hajj pilgrimage. Epidemiological information and typing results suggested wide dissemination of a limited number of domestic clones of N. meningitidis, manifesting as serogroups W-135, B and Y. Two clones of serogroup W-135 involved in the outbreak were genetically distinct from the 2000 or 2001 Hajj-related W-135 clone.

A prospective multi-centre study was conducted to assess the microbiological pattern and prognostic factors of bacteraemia and their impact on clinical outcome. All patients admitted to 41 Italian hospitals over 2 months, from whom one or more clinically significant organisms were isolated from blood culture, were studied according to a standardized protocol and case definition. A total of 156 episodes of bacteraemia were identified in 20601 patients. There were 3·9 episodes of nosocomially acquired bacteraemia and 3·7 episodes of community-acquired bacteraemia per 1000 admissions. The most frequent pathogens isolated were Gram-negative bacteria (44·9%) but Gram-positive species accounted for 40·4% of episodes. Fungal infections due to Candida spp. were found in 3·8% of episodes, and multiple pathogens were recovered from 9·6% of episodes. The clinical response to bacteraemia was classified as sepsis in 90 episodes (57·7%), severe sepsis in 21 (13·5%) and septic shock in 26 (16·7%); 19 episodes (12·2%) showed no clinical response. The total in-hospital mortality was 25·0%. By multivariate logistic regression, the variables which independently predicted mortality were increasing age, the presence of septic shock, infection with Gram-positive bacteria or fungi and nosocomial acquisition.

Although the great majority of antibiotics are prescribed outside hospitals, little is known about the prevalence and determinants of antibiotic resistance in the group of outpatients. Nasal swabs were taken from 627 consecutive patients aged 40 years or above attending general practitioners in Southern Germany. Staphylococcus aureus was cultured and minimal inhibitory concentrations to various antibiotics were tested. Nasal swabs of 152 patients were positive for S. aureus. Prevalence of resistance was 68·3, 8·3 and 0·7% for penicillin G, erythromycin, and oxacillin respectively. Antibiotic use within the last month was associated with erythromycin resistance [adjusted odds ratio (OR) 7·4; 95% confidence interval (CI) 1·0–53]. Besides a high prevalence of resistance to penicillinase-instable antibiotics we found only one (0·7%) methicillin-resistant S. aureus. Recent antibiotic use was associated with increased resistance to erythromycin.

Leptospirosis is endemic in the Andaman Islands, often occurring as outbreaks during the post-monsoon period. Pulmonary involvement is common and associated with high morbidity and mortality. During the investigation of an outbreak in North Andaman in 1996 an isolate was recovered from the blood of a patient with fever, headache, body aches and haemoptysis with respiratory distress as presenting symptoms. The isolate was characterized using the cross-agglutination absorption test (CAAT) and monoclonal antibodies (mAbs). The isolate showed typical morphology and characteristic motility of the genus Leptospira. Growth was inhibited at 13 °C and in the presence of 8-azaguanine. The isolate could not be identified with grouping sera representing 25 serogroups, CAAT and mAbs. A new serovar of a new serogroup is proposed. Genetic characterization using polymerase chain reaction (PCR) followed by sequencing of the PCR product and randomly amplified polymorphic DNA fingerprinting (RAPD) showed that the isolate was genetically similar to L. interrogans sensu stricto.

High overall vaccination levels sometimes hide pockets of poor coverage. We adopted a meta-population framework to model local aggregation of populations, and used this to investigate the effects of vaccination heterogeneity. A recent survey of antibody levels in a community with low vaccination levels in The Netherlands enabled us to assess the relative importance of local and long-range infective contacts, and thus identify feasible levels of aggregation in the meta-population model. In the aggregated model, we found that heterogeneity in vaccination coverage can lead to a much increased rate of infection among unvaccinated individuals, with a simultaneous drop in the average age at infection.

In Spain, vaccination against rubella was initiated in schoolgirls in the mid-1970s. In Gipuzkoa, subsequent extensions to the vaccination schedule culminated in 1992 with the introduction of the two-dose measles, mumps and rubella vaccine in children and adolescents of both sexes. Moreover, in 1985 a programme for the identification and vaccination of non-immune parturient women was implemented in the region's main hospital. The prevalence of rubella-susceptible parturient women decreased from 3·7% at the beginning of the study to <1·5% by 1992. Despite this overall decrease, 4·8% of adolescent parturients were susceptible to rubella during 2001–2002. From 1984, the number of reported cases of rubella (children and adults) progressively decreased until 1997, after which there have been no cases of indigenous rubella. There have been no cases of reported congenital rubella since 1984. These results indicate that the vaccine policy carried out in this geographical area has been effective in achieving considerable progress towards rubella elimination.

Historically, subtype B viruses in men who have sex with men (MSM) and injecting drug users (IDU) dominated the HIV epidemic in the United Kingdom, whereas non-B heterosexual infections dominate globally. Heterosexual contact is now the most common route of transmission in the United Kingdom. Here we monitor HIV subtype in Scotland, and link it to origin of infection. HIV-1 sequence was generated from new diagnoses and the subtype thus obtained linked with demographic data. Virus was subtyped from 80% (137/171) of all new diagnoses in Scotland. Of 58 individuals infected by heterosexual contact, 74% (43) harboured non-B viruses, contrasting with 7% (5/68) of those infected by IDU or MSM. Eighty-four per cent of non-Bs (46/55) were probably acquired outside the United Kingdom, but nine individuals probably acquired their non-B infection in the United Kingdom. Non-B subtypes of HIV-1 predominate in recently diagnosed, heterosexually acquired infections in Scotland and are present in all risk groups, even those with no exposure outside the United Kingdom.

In order to evaluate the incidence and risk factors of infection by hepatitis C virus (HCV) among injecting drug users (IDUs), we conducted a prospective cohort study of HCV- and human immunodeficiency virus (HIV)-negative IDUs in the North and East of France. A total of 231 HCV and HIV IDUs who had injected drugs at least once in their lifetime were followed up every 3 months over a 12-month period. Serum anti-HCV and anti-HIV were tested at inclusion in the study and at the end of the follow-up. Data on injecting practices were collected at inclusion and at each visit. Of the 231 participants included, 165 (71·4%) underwent a final HCV and HIV serum test. The incidence was nil for HIV infection and 9/100 person-years (95% CI 4·6–13·4) for HCV infection. In a multivariable analysis, we found that syringe and cotton sharing were the only independent predictive factors of HCV seroconversion.

Between October 1999 and May 2000, a total of 28 strains of influenza C virus were isolated in four Japanese prefectures: Yamagata, Miyagi, Saitama and Hiroshima. Antigenic analysis showed that the 28 isolates were divided into three distinct antigenic groups, and viruses belonging to different antigenic groups were co-circulating in each of the four prefectures. Phylogenetic analysis of the seven protein genes demonstrated that the viruses having a similar genome composition spread in various areas of Japan during the same period. Furthermore, phylogenetic analysis showed that most of the influenza C viruses isolated in various areas of the world between the 1970s and 1980s were closely related to the contemporary Japanese viruses in all gene segments. These observations suggest that the influenza C viruses cause epidemics in some communities during the same season and that antigenically and genetically similar influenza C viruses spread throughout Japan and may be circulating worldwide.

We attempted to predict epidemics of influenza B, focusing on B/Victoria/2/87-like (V) and B/Yamagata/16/88-like (Y) lineages, in Yamagata, Japan. We collected 9624 nasopharyngeal swabs for virus isolation from patients with respiratory infections between 1996 and 2003 and 237 sera for seroepidemiological analysis by haemagglutination–inhibition test in 2001. We isolated 424 V-lineage and 246 Y-lineage viruses during the study period. Three herald viruses in the 2000–2001 season enabled us to predict a V-lineage epidemic in the following season. However, another V-lineage epidemic occurred in the 2002–2003 season, although we caught four herald Y-lineage viruses, whose antigenic drift was suggested by seroepidemiological study, at the end of the previous season. Since the epidemiology of the two influenza B lineages remains unclear, a careful watch should be kept on these lineages in order to provide effective public-health strategies against future epidemics.

This study aims to investigate Severe Acute Respiratory Syndrome (SARS)-related behaviours of travellers returning to Hong Kong by air. A total of 820 travellers returning to Hong Kong by air were interviewed about their SARS-related behaviours in April 2003. Three quarters of the respondents wore a mask most/all of the time on board, 15% did so in public places at the travel destination. Perceived susceptibility to SARS at the destination predicted mask-wearing in public places and avoidance of crowded places, and perceived efficacy was a predictor for mask-wearing during flight. Approximately 16% of the respondents stated that they would delay their medical consultation for flu-like symptoms until returning to Hong Kong. Nearly 18·2% stated that they would not wear a mask in public places at the destination if they had flu-like symptoms. Education programmes, special services and effective thermal screening are required to minimize the chance of the spread of SARS by air travellers.

In July 2001, an outbreak of gastroenteritis occurred in Helsinki among children and adults after bathing in an outdoor wading pool. The epidemiological survey revealed that at least 242 persons were affected. Microbiological testing of both patient stool samples and of the pool water revealed the presence of two different gastroenteritis viruses: a norovirus (NV) and an astrovirus. Amplicon sequencing of the NV samples showed nucleotide sequence identity between the virus from patients and the water. After changing the pool water and the sand at the bottom of the pool followed by shock chlorination, no virus could be detected in the water. However, NV was continuously detected in the water outlet well as much as 8 months after the incident. Here we show how molecular methods aided in tracing the source of the epidemic and in finding the causative pathogens both in patients and in the environment.