A large outbreak of Escherichia coli O157 infections via school lunches occurred at primary schools in 1996 in Sakai City, Japan. As many as 10000 patients suffered from diarrhoea, haemorrhagic colitis and haemolytic uraemic syndrome (HUS). Using data on 288 inpatient school children affected by this outbreak, of whom 36 presented complete HUS and the remaining 252 tested positive for E. coli O157 culture, we attempted to identify predictors for the progression to HUS. Within the first 5 days of illness, clinical features associated with inpatients who developed HUS compared with those without HUS included a C reactive protein (CRP) level higher than 1·2 mg/dl (OR 44·26; 95% CI 5·83–336·23), a white blood cell (WBC) count greater than 11·0 × 109/1 (OR 5·03; 95% CI 27·13–11·87) and a temperature higher than 38·0 °C (OR 5·00; 95% CI 2·25–117·08). It can be concluded that these three factors are predictive factors for the development of HUS in patients with E. coli O157 infection, and patients who have two or all of these factors should be observed closely.

To understand the role of flagella and fimbriae of Escherichia coli O78[ratio ]K80 in avian colibacillosis, day-old chicks were dosed orally with defined afimbriate and or aflagellate mutants and colonization, invasion and persistence compared with that of the wild-type. In an invasion model, chicks were dosed with 1 × 105 c.f.u. of a single strain and mutants defective for type 1 fimbriae, curli fimbriae or flagella colonized livers by 24 h although the numbers of bacteria present were significantly less than the wild-type. Mutants colonized between 50 and 75% of spleens whereas the wild-type colonized 100% of spleens. Additionally, the numbers of mutant bacteria in colonized spleens were significantly less than the wild-type. Surprisingly, mutants defective for the elaboration of more than one appendage were no more attenuated than single mutants. In a persistence model, chicks were dosed with 1 × 102 c.f.u. of a single strain and mutants defective for type 1 or curli or flagella or any combination thereof persisted as assessed by cloacal swabbing for 5 weeks of the experiment less well than the wild-type. In an additional persistence model, chicks were dosed with 5 × 102 c.f.u. of each of wild-type and one mutant together. All mutants were significantly less persistent than the wild-type (P < 0·001) and one mutant which lacked type 1, curli and flagella, was eliminated within 2 weeks. Analysis of the trends of elimination indicated that flagella contributed to persistence more than curli, which contributed more than type 1 fimbriae. Here was evidence for a major role in colonization, invasion and persistence played by type 1, curli and flagella.

A model of the transmission of salmonella through the poultry meat production chain is developed, to predict the effects of intervention strategies for salmonella control. The model first describes the situation before intervention in terms of salmonella prevalences at flock level and some transmission parameters. After single control measures are translated into effects on these transmission parameters, the effects of sets of control measures (intervention strategies), can be calculated with the model. As research data are lacking, the model input parameters were derived from expert opinion. As an example, the effects of two intervention strategies proposed for the Dutch poultry industry are predicted. A sensitivity analysis is performed to indicate where the most effective control measures may be expected. Additionally, the reliability of the model predictions is studied by an uncertainty analysis. The use of the model as a tool for policy makers deciding about salmonella control strategies is discussed.

One-hundred and twenty-one isolates of Salmonella enterica serotype Montevideo, representing different biotypes and incidents of infection detected in the UK between 1977 and 1995, were analysed by EcoRI ribotyping, PvuII ribotyping and IS200 fingerprinting. Among the isolates examined, 7 EcoRI ribotypes, 5 PvuII ribotypes and 55 IS200 profile types were recognized and 4 arbitrary groups defined. All 33 isolates of biotype 2d belonged to EcoRI/PvuII ribotype 1/1 and IS200 lineage A and comprised Group I. The other 88 isolates of biotype 10di and its variants were assigned to Groups II–IV. All 27 isolates in Group II were of EcoRI/PvuII ribotype 2/2 and IS200 lineage B. Among the 43 isolates in Group III, 42 of which were of EcoRI/PvuII ribotype 3/3, IS200 analysis identified 38 profiles in lineages C–I. Six EcoRI/PvuII ribotypes and 8 IS200 profiles, mostly in lineages C–E, were recognized among the 18 isolates in Group IV. The combined use of biotyping and ribotyping, and to some extent IS200 profiling, has enhanced our understanding of the clonal structure of serotype Montevideo and provides a basis for further study.

Human salmonellosis in Germany has been an increasing problem since the 1980s, with a peak of 195000 reported cases in 1992. During the peak years, isolates of Salmonella Enteritidis (SE) predominated by far over other salmonella serovars (NSE) (80 vs. 20%). In a comparison of the clinical characteristics of 790 persons infected with SE to 175 persons infected with NSE, watery diarrhoea (OR 1·7) and high grade (> 39 °C) fever (OR 1·8) were independently associated with SE infection. When comparing possible risk factors for acquiring salmonella infection among patients with SE compared to those with NSE, consumption of raw eggs (OR 4·4; P = 0·0006) was the most significant alimentary risk factor for SE infection, while travel outside Europe was negatively associated with SE infection (OR 0·08; P = 0·0001). When comparing all patients with salmonella infection, regardless of serovar, with healthy controls, consumption of raw eggs (OR 30·3; P = 0·001), of raw or undercooked eggs (OR 1·9; P = 0·003), or having puppies, kittens or turtles (OR 6·8; P = 0·002), were risk factors for salmonellosis.

Antimicrobial susceptibilities of Vibrio cholerae strains isolated from cholera patients admitted to the Infectious Diseases Hospital, Calcutta, India for 6 years were analysed to determine the changing trends; 840 V. cholerae strains isolated in 1992–1997 were included in this study. Among V. cholerae serogoup O1 and O139, ampicillin resistance increased from 1992 (35 and 70%, respectively) to 1997 (both serogroups 100%). Resistance to furazolidone and streptomycin was constantly high among V. cholerae O1 strains with gradual increase in resistance to other drugs such as ciprofloxacin, co-trimoxazole, neomycin and nalidixic acid. V. cholerae O139 strains exhibited susceptibilities to furazolidone and streptomycin comparable with those of O1 strains. However, after initial increase in resistance to chloramphenicol and co-trimoxazole, all the V. cholerae O139 strains became susceptible to these two drugs from 1995 onwards. Both V. cholerae O1 and O139 remained largely susceptible to gentamicin and tetracycline. V. cholerae non-O1, non-O139 strains, in contrast, exhibited high levels of resistance to virtually every class of antimicrobial agents tested in this study especially from 1995. Kruskal–Wallis one-way analysis showed that V. cholerae O1 Ogawa serogroup exhibited significant yearly increase in resistance to nine antibiotics followed by non-O1 non-O139 and O139 strains to six antibiotics and two antibiotics respectively. Interesting observation encountered in this study was the dissipation of some of the resistant patterns commonly found among V. cholerae non-O1 non-O139 or O1 serogroups to the O139 serogroup and vice versa during the succeeding years.

The occurrence of extended-spectrum β-lactamase producing enterobacteria (ESBLE) has been prospectively surveyed in a neurosurgical intensive care unit (ICU). Of the 47 patients examined, 8 were identified as faecal carriers, and 2 of them developed a subsequent urinary tract infection. ESBLE were also detected in the immediate environment of five colonized and/or infected patients. All isolates were Klebsiella pneumoniae of a particular biotype which exhibited a similar antibiotype and produced an SHV-4 type β-lactamase. However, plasmid profiling and ribotyping revealed that strains isolated from seven patients of hall A were a single epidemic clone, whereas strains isolated from the eighth patient of hall B were different. Comparison between the characteristics of patients who carried an ESBLE during the surveillance period, and control patients who did not, showed that a recent surgery, and the length of ICU stay were significantly associated with the acquisition of ESBLE.

The aim of this study was to identify risk factors for acute diarrhoea (AD) during the summer in France. A matched case-control study was conducted at a national level among patients of 500 general practitioners (GPs). From July to September 1996, 468 case-control pairs were included. Cases were more likely than controls (i) to live away from their main residence (OR 3·0; 95% CI 1·6–5·7), (ii) to have returned from a country at high risk of AD (OR 4·6; CI 0·9–23·1), and (iii) to have been in contact with a case of AD (OR 2·0; CI 1·3–3·1). A significantly decreased risk of AD was found for consumption of well-cooked chicken (OR 0·5; CI 0·3–0·8) and raw or undercooked home-made egg-containing products (OR 0·6; CI 0·4–0·8). These findings suggest that travel to high-risk areas, or travel within France, and being in contact with a case of AD, are risk factors for the occurrence of AD in summer in France.

Results from statutory testing of private water supplies in nine Public Health Laboratories in England were compiled, and the effects of supply class, source, treatment and location on water quality were examined. A total of 6551 samples from 2911 supplies was examined, over a 2-year period, of which 1342 (21%) samples, and 949 (33%) supplies on at least one occasion, failed current regulations for Escherichia coli. Total coliforms, including E. coli, were detected in 1751 (27%) samples from 1215 (42%) supplies. The percentage of samples positive for E. coli was highest in summer and autumn, and lowest in winter. Samples taken from larger supplies and from boreholes were less frequently contaminated than those from other sources. Chlorination, filtration or UV light treatment improved the bacteriological quality of supplies, but still resulted in a low level of compliance with the regulations. The public health implications of the study are discussed.

The induction of immunological memory to serogroup A and C polysaccharides in UK infants immunized with three doses of a meningococcal A/C oligosaccharide CRM197 conjugate vaccine was investigated. Forty UK infants vaccinated previously with three doses of a meningococcal A/C oligosaccharide-CRM197 conjugate vaccine at 2, 3 and 4 months of age, were revaccinated at a mean age of 145·6 weeks with either a 10 or 50 μg dose of licensed meningococcal A/C polysaccharide vaccine. Serogroup-specific antibody and serum bactericidal antibody (SBA) responses were measured by enzyme-linked immunosorbent assay and serum bactericidal assays, respectively. Following challenge, anti-serogroup A and C polysaccharide antibody levels rose from pre-booster geometric mean concentrations (GMC) of 3·1 and 2·1 μg/ml respectively to 19·6 and 21·0 μg/ml 1 month post-booster. Serum bactericidal antibody geometric mean titres (GMTs) for serogroups A and C increased 156- and 113-fold from 2·1 and 7·1 pre-booster respectively to 327·4 and 800·7 post-booster. A serogroup A control group of 45 children received a 10 μg dose of licensed meningococcal A/C polysaccharide vaccine (with no prior history of serogroup A vaccination) had serogroup A SBA GMTs of 2·3 pre- vaccination rising to 8 post-vaccination with corresponding GMCs of 0·8 and 10·8 μg/ml. These rises in SBA following serogroup A/C conjugate vaccination are indicative of immunological priming.

Close contacts of cases of meningococcal disease are at increased risk of disease themselves. We identified household-like contacts of index cases, to investigate whether relevant target groups are informed, receive and follow recommended chemoprophylaxis and vaccination, and to ascertain the time delay for implementation of these measures. A telephone interview of 172 households of index cases and a questionnaire survey among 634 parents of contacts of cases in institutions were carried out. Results were compared with reports from Medical Officers of Health. In 21% of the cases, Medical Officers reported fewer household-like contacts than were identified in this study. Written information was effective. However, 59% of households, and 36% of parents of contacts in institutions felt a lack of information about how the disease is acquired, the risk and signs of illness. For household-like contacts the coverage rate for chemoprophylaxis with an appropriate drug was 90% and for vaccination 59%. No secondary cases occurred among those treated with chemoprophylaxis, but among those not treated, there were two secondary cases. The study design provided a useful audit methodology to evaluate the completeness of implementation and the success of prophylactic measures for meningococcal disease.

We reviewed retrospectively all invasive Haemophilus influenzae (Hi) infections in adults ascertained from reference laboratory records and notifications from five NHS regions over the 5 years from 1 October 1990, a period encompassing the introduction of routine Hib childhood immunization (October 1992). A total of 446 cases were identified, a rate of 0·73 infections per 105 adults per annum. Though numbers of Hib infections in adults fell after the introduction of Hib vaccines for children (P = 0·035), and there was no increase in infections caused by other capsulated Hi serotypes, total numbers of invasive Hi infections increased due to a large rise in infections caused by non-capsulated Hi (ncHi) strains (P = 0·0067). There was an unexpectedly low rate of infections in those aged 75 years or more (P < 0·0001). The commonest clinical presentations were pneumonia with bacteraemia (227/350, 65%) and bacteraemia alone (62/350, 18%) and the highest rates of disease were in the 65–74 years age group (P < 0·0001). Clinical presentation was not influenced by the capsulation status of the invading Hi strain. 103/350 cases (29%) died within 1 month, and 207/350 (59%) within 6 months of their Hi infection. Case fatality rates were high in all age groups. Pre-existing diseases were noted in 220/350 cases and were associated with a higher case fatality rate (82% vs. 21%, P < 0·0001). After the introduction of Hib immunization in children, invasive Hib infections in unimmunized adults also declined, but the overall rate of invasive Hi disease in adults increased, with most infections now caused by non-capsulated strains. Physicians and microbiologists should be aware of the changing epidemiology, the high associated mortality and high risk of underlying disease. Invasive haemophilus infections in adults should be investigated and treated aggressively.

The age-specific immunity to human parvovirus infection was estimated in Victoria, Australia using prospectively collected samples from the Royal Children's Hospital, the Royal Women's Hospital and the Australian Red Cross Blood Service and from sera stored at the Victorian Infectious Diseases Reference Laboratory (VIDRL). All testing was performed at VIDRL using a commercial enzyme-linked immunosorbent assay (Biotrin). Of the 824 sera tested, 28% of those drawn from people aged 0–9 years contained protective antibodies to human parvovirus. This rose to 51% in the next decade of life. There was then a slow rise to about 78% immunity over 50 years of age. An analysis of all requests for parvovirus serology at VIDRL from 1992 to 1998 suggested that parvovirus tended to occur in 4-year cycles, with 2 epidemic years followed by 2 endemic years. A review of published reports of parvovirus immunity suggested that parvovirus infection may be more common, with a correspondingly higher proportion of the community immune, in temperate as opposed to tropical countries.

The prevalence of antibodies to hepatitis A virus was assessed in a Dutch nationwide sample (n = 7367). A questionnaire was used to study the association with various sociodemographic characteristics. Overall, 33·8% (95% CI 31·6–36%) of the population had hepatitis A antibodies. The seroprevalence was less than 10% in people under 35; it increased from 25% at 35 years to 85% at 79 years. For those 15–49 years of age, Turks (90·9%) and Moroccans (95·8%) had greater seroprevalence than autochthonous Dutch (20·2%) and other Western people (25%). Low or middle socio-economic status, as indicated by the highest educational level achieved, was associated with greater seroprevalence, independently of age and reported immunization (OR 2·11 and 1·45; 95% CI 1·67–2·67 and 1·11–1·89, respectively). These data suggest autochthonous Dutch and other Westerners born after World War II were exposed to hepatitis A during childhood less frequently than older birth cohorts. Thus, more susceptibility is likely in the coming decades. Since this means a greater risk of outbreaks in future years, and since morbidity and mortality are more frequent in older persons, studying the cost effectiveness of selective and general vaccination might be worthwhile.

We conducted a community-based cluster sample survey of rubella sero-epidemiology in Addis Ababa, Ethiopia in 1994. Among 4666 individuals for whom complete data were available, rubella antibody prevalence was 91% (95% confidence interval: 90, 92). On multivariable analysis, seroprevalence was lower among individuals who were resident in Addis Ababa for 1 year or less. Approx. 50% seroprevalence was attained by age 4 years, and the estimated average age at infection was 5·2 years. The highest age-specific force of infection was estimated to occur in 5- to 9-year-olds. The early age at infection corresponded with a low estimated incidence of congenital rubella syndrome (CRS) of 0·3 per 1000 live births, equivalent to nine cases of CRS in 1994. The predicted critical level of immunity for elimination of rubella via vaccination was 85–91%, requiring 89–96% coverage with a vaccine of 95% effectiveness. Unless very high coverage of rubella vaccine could be guaranteed, the introduction of childhood vaccination could increase the incidence of CRS in Addis Ababa.

An outbreak of gastroenteritis followed a meal in a large hotel during which one of the diners vomited. The clinical features of the illness suggested Norwalk-like virus (NLV, small round structured virus) infection, and this was confirmed by electron microscopy and reverse transcriptase polymerase chain reaction (RT–PCR) of stool samples. Further characterization of the virus by nucleotide sequence analysis of the PCR amplicons revealed identical strains in all the affected individuals. The foods served at the meal could not be demonstrated to be the cause of the outbreak. Analysis of attack rates by dining table showed an inverse relationship with the distance from the person who vomited. No one eating in a separate restaurant reported illness. Transmission from person-to-person or direct contamination of food seems unlikely in this outbreak. However, the findings are consistent with airborne spread of NLV with infection by inhalation with subsequent ingestion of virus particles.

We examined clinical and epidemiological features of 575 laboratory-confirmed cases of vibrio gastroenteritis in Alabama, Florida, Louisiana, and Texas from 1988 to 1997 (the US Gulf of Mexico Regional Vibrio Surveillance System). Illnesses occurred year round, with peaks in spring and autumn. Illnesses lasted a median of 7 days and included fever in half of patients and bloody stools in 25% of patients with relevant information. Seventy-two percent of patients reported no underlying illnesses. In the week before onset, 236 (53%) of 445 patients for whom data were available ate raw oysters, generally at a restaurant or bar. Educational efforts should address the risk of vibrio gastroenteritis for raw oyster consumers, including healthy individuals. Further studies should examine environmental conditions affecting vibrio counts on seafood and processing technologies to enhance the safety of raw oysters.

A total of 15662 clinical samples were analysed for enterovirus (EV) isolation in cell cultures during a 10-year period (1988–97). Furthermore, 210 isolates of EV obtained in primary laboratories within Spain from patients with meningitis were characterized. The total number of EV typed was 758, including 727 non-polio EV and 31 Sabin-like (SL) polioviruses. Twenty-eight EV serotypes were represented. Echoviruses comprised 90% (653/727) of fully typed non-polio EV. The four most prevalent serotypes were echovirus 30, echovirus 9, echovirus 6 and echovirus 4. Echovirus 30 was the main serotype associated with meningitis. Echovirus 9 was the aetiological agent in 20 outbreaks of meningitis while the occurrence of echovirus 6 was localized in 1 year (1997). Coxsackieviruses A and B occurred in 3 and 7% of the non-polio EV respectively. Coxsackievirus B5 presented the relative greater abundance. This paper examines the epidemiology of EV in Spain to serotype level over a 10-year period with special attention to non-polio EV associated with meningitis.

In order to conduct a survey of influenza viruses entering Japan via travellers arriving by airplanes, gargle solutions were collected from passengers who reported to the quarantine station of Nagoya International Airport complaining of respiratory symptoms. From 504 samples collected between August 1996 and March 1999, 30 influenza virus strains were isolated. Twenty-eight of the isolates were influenza A (H3N2) viruses and two were influenza B viruses. No H1N1 virus was isolated. Among 28 isolates of H3N2 virus, 3 strains were obtained outside the influenza season. Nucleotide sequences of the haemagglutinin (HA) genes of these isolates along with those from domestic patients were analysed in order to determine the influence of imported influenza viruses by travellers on epidemics in Japan. From the phylogenetic and chronological aspects, the possibility was suggested in one case in 1997/8 and two in the 1998/9 season that imported virus by travellers may have influenced the domestic influenza epidemics.

Linking continuous community-based morbidity recording of influenza-like illness (ILI) with virological sampling has consistently proved its value as one of the earliest indicators of circulating influenza activity. The clinical morbidity recording in the Portuguese national surveillance network, during a 7-year period, and the contribution of different diagnostic techniques, including virus isolation, multiplex RT–PCR, immunocapture enzyme linked immunoassay (EIA) and complement fixation tests (CFTs) for the detection of influenza in such a community-based setting is described and evaluated in this study. There was good correlation between the increase of morbidity, total samples taken and the detection of influenza virus by all the methods although this was less evident for virus isolation and EIA than for RT–PCR or serology. From a total of 1685 throat swabs collected from cases of ILI, 43·6% were RT–PCR positive, 17·5% were positive by capture EIA and in 5% virus isolates were made. The detection of influenza by RT–PCR occurred earlier than by any other method and showed the best correlation with epidemic patterns of morbidity registration. We conclude that in surveillance systems where virus culture is sub-optimal, RT–PCR provides a rapid, sensitive, specific method for detecting influenza viruses from community-based sampling.