We estimated age-specific herpes zoster (HZ) incidence rates in the Kaiser Permanente Northwest Health Plan (KPNW) during 1997–2002 and tested for secular trends and differences between residents of two states with different varicella vaccine coverage rates. The cumulative proportions of 2-year-olds vaccinated increased from 35% in 1997 to 85% in 2002 in Oregon, and from 25% in 1997 to 82% in 2002 in Washington. Age-specific HZ incidence rates in KPNW during 1997–2002 were compared with published rates in the Harvard Community Health Plan (HCHP) during 1990–1992. The overall HZ incidence rate in KPNW during 1997–2002 (369/100000 person-years) was slightly higher than HCHP's 1990–1992 rate when adjusted for age differences. For children 0–14 years old, KPNW's rates (182 for females, 123 for males) were more than three times HCHP's rates (54 for females, 39 for males). This increase appears to be associated with increased exposure of children to oral corticosteroids. The percentage of KPNW children exposed to oral corticosteroids increased from 2·2% in 1991 to 3·6% in 2002. Oregon residents had slightly higher steroid exposure rates during 1997–2002 than Washington residents. There were significant increases in HZ incidence rates in Oregon and Washington during 1997–2002 among children aged 10–17 years, associated with increased exposure to oral steroids.

An outbreak of acute gastroenteritis of suspected viral aetiology occurred in April 2003 in the British Royal Fleet Auxillary ship (RFA) Argus deployed in the Northern Arabian Gulf. There were 37 cases amongst a crew of 400 personnel. Of 13 samples examined from cases amongst the crew, six enteric viruses were detected by reverse transcriptase polymerase chain reaction (RT–PCR). Five different viruses were identified including, three norovirus genotypes, a sapovirus and a rotavirus. No multiple infections were detected. A common food source was implicated in the outbreak and epidemiological analysis showed a statistically significant association with salad as the source of the outbreak, with a relative risk of 3·41 (95% confidence interval of 1·7–6·81) of eating salad on a particular date prior to the onset of symptoms. Faecal contamination of the salad at source was the most probable explanation for the diversity of viruses detected and characterized.

Foodborne transmission is estimated to account for 95% of non-typhoidal Salmonella infections reported in the United States; however, outbreaks of salmonellosis are rarely traced to food handlers. In August 2000, an increase in Salmonella serotype Thompson infection was noted in Southern California; most of the cases reported eating at a restaurant chain (Chain A) before illness onset. A case-control study implicated the consumption of burgers at Chain A restaurants. The earliest onset of illness was in a burger bun packer at Bakery B who had not eaten at Chain A but had worked while ill. Bakery B supplied burger buns to some Chain A restaurants in Southern California and Arizona. This outbreak is notable for implicating a food handler as the source of food contamination and for involving bread, a very unusual outbreak vehicle for Salmonella. Inadequate food-handler training as well as delayed reporting to the health department contributed to this outbreak.

Escherichia coli O157 outbreaks were identified in Minnesota in February 2003 involving seven persons and in Colorado in July 2003 involving 13 persons. Case isolates from the two states had matching pulsed-field gel electrophoresis (PFGE) patterns. Independent case-control studies linked infections in each outbreak with eating alfalfa sprouts that were traced to the same seed distributor. The Colorado sprouter reportedly complied with the Food and Drug Administration (FDA) sprout guidance, whereas the Minnesota sprouter did not. These investigations revealed that increased compliance with existing FDA guidance is needed and that additional research is needed to improve the alfalfa seed decontamination process. This reaffirms the FDA recommendation that raw alfalfa sprouts should be considered potentially contaminated and avoided by persons at high-risk such as the elderly, young children, and immunocompromised persons. PFGE played an essential role in linking these two temporally and geographically distinct E. coli O157 outbreaks.

The routine title of the long ‘note’ by Glenny and Südmersen reproduced here [1] hides two of the most significant findings in theoretical and applied immunology: a brief description of diphtheria toxoid and a comprehensive account of the primary and secondary immune response. The introduction of antitoxin treatment of diphtheria was heralded, in 1896, without exaggeration as ‘the most important advance of the [19th] Century in the medical treatment of acute infective disease’ [2]. However, there were problems with the standardization and potency of antitoxin. The former was solved by Ehrlich who, in his analysis of toxin–antitoxin interaction, postulated the existence of ‘toxoid’, a non-toxic component of toxin which combined with antitoxin [3]. The latter was solved by the general observation that repeated injections of gradually increased doses of toxin induced increasingly potent antitoxins, an important basis upon which the present paper was founded.

This paper uses a graph-theoretical approach to investigate the properties of the observed network of disease transmission in the 2001 foot-and-mouth epidemic in the United Kingdom. This analysis revealed both global and local heterogeneity in the contact pattern between the infected premises in the first 3 weeks of the disease. In particular, the global heterogeneity contributed to the failure of the culling strategy imposed by the UK government. However, a more effective strategy targeting selective deletion of key premises in the network was not available once the epidemic had begun. We recommend that post-hoc analyses of this sort should become part of preventative and proactive policy rather than part of a reaction to an ongoing crisis.

We compared serotypes, drug susceptibility and presence of virulence-related genes in diarrhoeagenic Escherichia coli isolates from children <5 years from Kenya (n=82) and Japan (n=47). Multiplex PCR was used to detect genes coding for enteroaggregative adherence (aggR), heat-stable toxin (st), heat-labile toxin (lt), verotoxin (vt), attaching and effacing mechanism (eaeA), enteroaggregative E. coli heat-stable enterotoxin 1 (astA) and enteroinvasive mechanism (invE). Kenyan E. coli O-serotypes were more diverse than those from Japan (29 vs. 12 serotypes) and exhibited high level multidrug resistance to World Health Organization (WHO) recommended antibiotics. Resistance rates to tetracycline, ampicillin and sulphamethoxazole–trimethoprim were 70·7, 65·9 and 68·3% respectively, but resistance to sulphamethoxazole–trimethoprim among the E. coli isolates from Japan was low (2·1%). Kenyan isolates harboured virulence-related genes in high frequency (82·9%) compared to those from Japan (25·5%) with aggR and astA being the most frequently detected genes. The presence of multiple virulence genes was associated with multidrug resistance and this merits further investigation.

Seasonal peaks in both human campylobacter infections and poultry isolates have been observed in several European countries but remain unexplained. We compared weekly data on human campylobacter infections with thermophilic Campylobacter isolation rates from fresh, retail chicken samples (n=514) purchased weekly in Wales between January and December 2002. Human isolates (n=2631) peaked between weeks 22 and 25 (early June) and chicken isolates (n=364) between weeks 24 and 26 (late June). In the absence of a temporal association, we postulate that the seasonal rise in humans is not caused by a rise in isolation rates in poultry but that both are more likely to be associated with a common, but as yet unidentified, environmental source.

Three sources of data (general practice episode data from the Weekly Returns Service of the Royal College of General Practitioners, national hospital admission data for England and national mortality data by date of death) were examined separately in each winter (1994/1995 to 1999/2000) to investigate the impact of influenza on circulatory disease. Weekly data on incidence (clinical new episodes) hospital emergency admissions and deaths certified to circulatory disorders and to respiratory diseases (chapters VII and VIII of ICD9) during influenza epidemic periods (defined from combined clinical/virological surveillance) were examined in age groups 45–64, 65–74 and [ges ]75 years. Data collected in the four winters in which there were substantial influenza A epidemics were consolidated for the period 6 weeks before to 6 weeks after each peak of the epidemic, and associations between the variables at different time lags examined by calculating cross-correlation coefficients. We also examined deaths due to ischaemic heart disease (IHD) as a proportion of all circulatory deaths and deaths due to influenza/pneumonia as a proportion of all respiratory deaths. There were no increases of GP episodes nor of emergency admissions for circulatory disorders in any of the three age groups during epidemic periods. Increased circulatory deaths occurred in all age groups and particularly in the oldest group. The large cross-correlation coefficients of deaths (circulatory and respiratory) with GP respiratory episodes at weekly lags of 0, −1 and 1 were evidence that the deaths and episode distributions were contemporaneous. The ratios of excess circulatory deaths relative to excess respiratory deaths during epidemic periods were 0·74 (age 45–64), 0·72 (65–74) and 0·57 ([ges ]75 years). Increased circulatory deaths contemporary with new incident cases of respiratory episodes but with no concomitant increase in admissions suggests rapid death during the acute phase of illness. Influenza contingency planning needs to take account of these deaths in determining policy for prophylaxis and in providing facilities for cardio-respiratory resuscitation.

The microbiology of domestic kitchens in the homes of subjects who had suffered sporadic Salmonella infection (cases) was compared with control domestic kitchens. Case and control dishcloths and refrigerator swabs were examined for the presence of Salmonella spp., total Enterobacteriaceae counts and total aerobic colony counts. Salmonella spp. were isolated from both case and control dishcloths and refrigerators but there were no significant differences between the two groups. Colony counts were similar in case and control dishcloths and refrigerator swabs. There was no relationship between the total counts and presence of Salmonella. There was no evidence that cases of Salmonella infection were more likely to have kitchens which were contaminated with these bacteria or have higher bacterial counts than controls. Total bacterial counts were poor indicators of Salmonella contamination of the domestic kitchen environment. Further factors which could not be identified by a study of this design may increase risk of Salmonella food poisoning. These factors may include individual susceptibility of the patient. Alternatively, sporadic cases of Salmonella food poisoning may arise from food prepared outside the home.

We investigate the epidemiology of 12 Verocytotoxin-producing Escherichia coli (VTEC) serogroups observed in a calf cohort on a Scottish beef farm. Fitting mathematical models to the observed time-course of infections reveals that there is significant calf-to-calf transmission of VTEC. Our models suggest that 40% of all detected infections are from calf-to-calf transmission and 60% from other sources. Variation in the rates at which infected animals recover from infection by different VTEC serogroups appears to be important. Two thirds of the observed VTEC serogroups are lost from infected calves within 1 day of infection, while the rest persist for more than 3 days. Our study has demonstrated that VTEC are transmissible between calves and are typically lost from infected animals in less than 1 week. We suggest that future field studies may wish to adopt a tighter sampling frame in order to detect all circulating VTEC serogroups in similar animal populations.

A new B/Shangdong/7/97-like influenza virus (Victoria/2/87 lineage) predominated during the 2002/2003 epidemic season in Finland and was estimated to account for 2246 of the 13496 feverish upper respiratory tract infections (URIs) occurring among conscripts in the Finnish army. The incidence (1716/10000 conscripts) was indicative of moderate epidemic activity at most. Analysis of the cross-reactive antibodies induced in 1988 suggests that the basis of the protection was probably established during the childhood of the conscripts. Vaccination in autumn 2002 prevented 42% of the URIs during the influenza B outbreak and 71% (95% CI 42–85) of infections interpreted as influenza B. Despite the low genetic variability of the Shangdong/7/97-like viruses, breakages of a potential glycosylation site in haemagglutinin (HA1, position 197) were frequent; their biological significance is discussed. The Shangdong/7/97-like strains were HA1/NA reassortants, as were also the less abundant strains that for HA1 belonged to the B/Yamagata/16/88 lineage. A further reassortment, which probably emerged during the outbreak in one of the garrisons, supports our hypothesis that circumstances in these settings may especially favour the emergence of diversity by reassortment.

In Scotland, between 1995 and 2000 there were between 4 and 10 cases of illness per 100000 population per year identified as being caused by Escherichia coli O157, whereas in England and Wales there were between 1 and 2 cases per 100000 population per year. Within Scotland there is significant regional variation. A cluster of high rate areas was identified in the Northeast of Scotland and a cluster of low rate areas in central-west Scotland. Temporal trends follow a seasonal pattern whilst spatial effects appeared to be distant rather than local. The best-fit model identified a significant spatial trend with case rate increasing from West to East, and from South to North. No statistically significant spatial interaction term was found. In the models fitted, the cattle population density, the human population density, and the number of cattle per person were variously significant. The findings suggest that rural/urban exposures are important in sporadic infections.

The molecular epidemiology of 98 isolates of Salmonella serovar Agona (n=27), S. Montevideo (n=42) and S. Senftenberg (n=29) from wild-living gulls, fish-meal factories, feed factories, humans and domestic animals was investigated using pulsed-field gel electrophoresis (PFGE) and computerized numerical analysis. Two of the S. Agona profiles were identified both in gulls and in two of the factories. In addition, one of these profiles was detected in two infected poultry farms. Two of the S. Montevideo profiles were also identified both in gulls and in two of the factories, and one of these profiles was observed in a human isolate. Four factories shared an identical S. Senftenberg profile. The S. Senftenberg profile found in gulls was not identified in any other source investigated. The presence of isolates with identical PFGE profiles indicates potential epidemiological links between different factories, as well as between gulls and factories.

In 2001 Salmonella enterica serovar Typhimurium definitive phage-type (DT) 126 was isolated at higher frequency in Australia compared to other S. Typhimurium phage types and in comparison to previous years. Associated with this increase was the implication of this phage type in a number of food-related outbreaks. We compared fluorescent amplified fragment length polymorphism (FAFLP) to pulsed-field gel electrophoresis (PFGE), the current ‘gold standard’ for molecular typing of Salmonella for the discrimination between outbreak-associated isolates and epidemiologically unrelated DT126 strains. FAFLP showed a greater ability to discriminate between isolates than PFGE, with 16 groups of clusters or individual isolates with <90% similarity to each other compared to three groups as determined by PFGE. Both methods were able to discriminate between isolates from two separate outbreaks in South Australia and isolates associated with an outbreak at a restaurant in New South Wales. The resolving power of both methods was not sufficient to separate all epidemiologically unrelated DT126 isolates from the outbreak isolates. We conclude that amplified fragment length polymorphism is a useful tool to assist in the discrimination of S. Typhimurium DT126 isolates.

Measles has been known as a highly contagious serious infection in man for centuries. After a prodromal fever, patients often experience coryza, cough and conjunctivitis followed by a blotchy rash. The disease is more severe in infants and adults with death resulting from encephalitis or pneumonia. Malnourished and immunosuppressed people are also more prone to serious complications and death. Subacute sclerosing panencephalitis (SSPE) is a rare complication, occurring as late sequela several years after measles infection at a rate of 1–5 per million cases.

The aim of this study was to estimate transmission parameters of enterotoxigenic F4+ Escherichia coli F4 (F4+ E. coli) in groups of early weaned piglets with F4-receptor-positive (F4R+) and F4-receptor-negative piglets (F4R−). Transmission of F4+ E. coli was quantified in four heterogeneous groups of F4R+ and F4R− piglets. Infectiousness was determined by the number of F4+ E. coli/g faeces shed during 8 days. Transmission parameters were estimated using generalized linear models assuming a stochastic SIR model. F4R+ piglets were found to be more susceptible than F4R− piglets, but F4R+ and F4R− piglets were not different in infectiousness. The reproduction ratios for homogeneous F4R+ and F4R− populations were estimated as 6·37 (95% CI 1·89–21·48) and 0·02 (95% CI 0·00–1·13) respectively. The implication of these results is that in order to prevent major outbreaks, the fraction of F4R+ piglets should be small (approximately 10% or less). Therefore, selective breeding programmes could contribute to reducing F4+ E. coli-related diarrhoea and transmission.

During its first century the journal attracted well over 100 papers on poxviruses. During the last 50 years this was probably due in part to the fact that Allan Downie, the world's leading poxvirus authority helped to edit the journal from 1951 to 1982. This expertise and association was acknowledged by the publication of a special academic tribute of 12 papers, including 5 on poxviruses, in 1982 (89: 353–478).

Two elementary schools were served lunches that were cooked in the same kitchen. An outbreak of Escherichia coli O157:H7 occurred at one school where the dishes that were prepared for the school were lukewarm and kept for 33 min at an average temperature of 45 °C before serving. However, no outbreak occurred at the other school where dishes were hot and were kept for 60 min at an average temperature of 50 °C before serving. In a series of experiments on the survival of E. coli O157:H7 in the liquid portion of similarly prepared food, the population of E. coli O157:H7 was reduced by 10−3 by heating at 50 °C for 60 min and by only 10−1 by heating at 45 °C for 40 min. Further, E. coli O157:H7 survived at 45 °C for 40 min but not at 50 °C for 60 min at pH 4·0 with a 4·0% salt concentration that was similar to that of the liquid part of the food. These results indicate that pH and salt concentration of cooked food markedly affect the survival of E. coli O157:H7 and help to explain the occurrence of the disease outbreak at only one of the schools.

During 2002–2003 increased numbers of notified salmonellosis due to S. enterica serovar Agona were observed in Germany. In order to understand the recent spread of this serovar and to trace the route of infection to its source, a new phage-typing scheme and pulsed field gel electrophoresis (PFGE) were used to analyse these isolates. By using 14 bacteriophages, 52 phage types were distinguished among the S. Agona strains. PFGE also differentiated 52 different patterns. A combination of both methods generated 94 clonal types among 165 S. Agona strains originating from Germany and other countries including the United States, United Arab Emirates, Turkey, India, Austria and Finland, indicating a great biological diversity within this serovar. However, 36 recent S. Agona isolates from infantile gastroenteritis in Germany, from an untreated batch of aniseed imported from Turkey and from fennel-aniseed-caraway infusion (packed in tea bags) revealed clonal identity indicating their epidemiological relatedness as a new source of infection. It is suggested that strains of S. Agona will continue to be of public health concern, and that phage typing together with PFGE typing should be applied as reliable and rapid tools for epidemiological subtyping and future monitoring.