The purpose of this article is to define the distinguishing characteristics of food-borne streptococcal pharyngitis by reviewing the literature. The main cause of this infection lies in poor handling and preservation of cold salads, usually those which contain eggs and are prepared some hours before serving. A shorter incubation period and a higher attack rate (51–90%) than in transmission by droplets was noted. The epidemics tend to occur in warm climates and in the hottest months of the year. Streptococcus pyogenes seems to originate from the pharynx or hand lesions of a food handler. In comparison to airborne transmission symptoms such as sore throat, pharyngeal erythema, and enlarged tonsils, submandibular lymphadenopathy are more frequent than coughing and coryza. Seven out of 17 reports revealed an M-untypeable serotype, which may possess virulent characteristics. Penicillin prophylaxis was shown to limit additional spread of the infection. There were no non-suppurative sequels, and suppurative sequels were very rare. We assume that the guidelines for the prevention of food poisoning would apply to food-borne streptococcal pharyngitis. Food handlers should be supervised to ensure they comply with strict rules of preparation and storage of food. Cold salads, especially those containing eggs, should not be left overnight before serving.

This is a case-control study aimed at identifying risk factors for intestinal infection with Campylobacter jejuni. Cases were defined as subjects with diarrhoea occurring in community cohorts or presenting to General Practitioners (GPs) with Campylobacter jejuni in stools. Controls were selected from GP lists or cohorts, matched by age, sex, and GP practice. Travel abroad and consumption of chicken in a restaurant were statistically significantly associated with being a case. There was no statistically significant risk associated with consumption of chicken other than in restaurants nor with reported domestic kitchen hygiene practices. Consumption of some foods was associated with a lower risk of being a case. Most cases remained unexplained. We suggest that infection with low numbers of micro-organisms, and individual susceptibility may play a greater role in the causation of campylobacter infection than previously thought. It is possible that in mild, sporadic cases infection may result from cross contamination from kitchen hygiene practices usually regarded as acceptable. Chicken may be a less important vehicle of infection for sporadic cases than for outbreaks, although its role as a source of infection in both settings requires further clarification in particular in relation to the effect of domestic hygiene practices. The potential effect of diet in reducing the risk of campylobacteriosis requires exploration.

A quantitative risk assessment model investigating the risk of human infection with campylobacter from the consumption of chicken meat/products is currently being formulated. Here such an approach is used to evaluate the probability that a random bird, selected at slaughter from Great Britain's national poultry flock, will be campylobacter-positive. This is determined from the probability that a flock chosen at random contains at least one colonized bird and the within-flock prevalence of such a flock at slaughter. The model indicates that the probability bird chosen at random being campylobacter-positive at slaughter is 0·53. This probability value has associated uncertainty, the 5th percentile being 0·51 and the 95th percentile 0·55. The model predicts that delaying the age at first exposure to campylobacter can have a significant impact on reducing the probability of a bird being campylobacter-positive at slaughter. However, implementation of current biosecurity methods makes this difficult to achieve.

The incidence and antimicrobial resistance among clinical isolates of salmonella at a university hospital in Taiwan between 1983 and 1999 are summarized in this report. A total of 7986 isolates were analysed. Serogroup B has been the most prevalent over the years, with an apparently continuous decline after 1995. Concordant decrease was also found among S. choleraesuis and S. typhi isolates in recent years. In contrast, the proportion of serogroup D strains increased significantly after 1996. S. typhi remained relatively susceptible to most of the antimicrobial agents examined. For non-typhoidal isolates, antimicrobial resistance to ampicillin (62%), chloramphenicol (67%), and sulfamethoxazole-trimethoprim (37%) was relatively higher than that reported elsewhere. Newer generation cephalosporins and fluoroquinolones remained effective over the years, although emerging resistance to these drugs has been noticed since 1992. A more prudent selection and use of antimicrobial agents, in both humans and animals, and a continuous surveillance of resistance are essential in the future.

To determine environmental risk factors for sporadic E. coli O157 infection in Scotland we undertook a prospective, matched case-control study between 1 October 1996 and 31 March 1999. One hundred and eighty-three cases and 545 matched controls were recruited. Contact with animal faeces (OR = 3·65; 95% CI 1·81, 7·34; P < 0·0005) and likely contact with animal faeces (OR = 4·8; 95% CI 2·42, 9·48; P < 0·0005) emerged as strong risk factors for infection. Certain exposures (mainly food-related) were inversely associated with infection i.e. were statistically protective. Most striking was the consumption of bottled water (OR = 0·28; 95% CI 0·15, 0·52; P < 0·0005). Transmission of E. coli O157 does not occur simply through contaminated food. Members of the public need to be aware of the potential for acquiring E. coli O157 through contamination of the environment with animal faeces so that they may take measures to mitigate their risk.

An outbreak due to Shiga toxin-producing Escherichia coli O26[ratio ]H11 (STEC) occurred at a nursery in southeastern Japan in 1997. Thirty-two children had watery or bloody diarrhoea but none of them suffered from haemolytic-uremic syndrome. All of the STEC O26 were isolated during the period from 23 July to 22 August from 24 children, 3 nurses, and 2 food samples. These organisms had stx1 and eae genes but none of the other genes for which we tested (stx2, bfp, and EAF plasmid). They also possessed multiple antimicrobial resistances, which were encoded by a transmissible plasmid, and showed mostly identical genomic pulsed-field gel electrophoretic patterns. The results of this investigation suggested that contaminated food was the main contributing factor to this multiple antimicrobial-resistant STEC O26 infection, and person-to-person transmission also contributed to the spread of this outbreak.

We prospectively studied diarrhoea incidence among 1655 children < 5 years of age in northern Vietnam for 1 year using primarily passive surveillance. Standard culture methods were used to detect bacterial pathogens. Overall 2160 cases occurred (1·3 cases/child per year). Peak rates of diarrhoea occurred in children < 12 months old. Rates ranged from 3·3 cases/child per year in children < 1 year old, to 0·7 cases/child per year in 4-year-olds. Campylobacter, shigella and enterotoxigenic Escherichia coli were most commonly isolated. Rates detected by active surveillance were about twice those detected passively. S. flexneri was the most common shigella serogroup (65%). S. flexneri serotypes 6, 4, 1 and Y were most common, but 40% were untypable using commercial antisera. The data illustrate important regional differences in pathogen prevalence and shigella serotype distribution. Shigella vaccine development strategies, commonly targeting S. flexneri 2a, S. sonnei and S. dysenteriae 1, will have little impact on diarrhoea rates in Vietnam.

We conducted a study in a squatter settlement in Karachi, Pakistan where residents report commonly washing their hands to determine if providing soap, encouraging hand washing, and improving wash-water quality would improve hand cleanliness. We allocated interventions to 75 mothers and collected hand-rinse samples on unannounced visits. In the final model compared with mothers who received no hand-washing intervention, mothers who received soap would be expected to have 65% fewer thermotolerant coliform bacteria on their hands (95% CI 40%, 79%) and mothers who received soap, a safe water storage vessel, hypochlorite for water treatment, and instructions to wash their hands with soap and chlorinated water would be expected to have 74% fewer (95% CI 57%, 84%). The difference between those who received soap alone, and those who received soap plus the safe water vessel was not significant (P = 0·26). Providing soap and promoting hand washing measurably improved mothers' hand cleanliness even when used with contaminated water.

We analysed a strain collection representative of the overall Neisseria meningitidis population circulating in an open community (46000 inhabitants, Spain) during an endemic period (30 isolates from patients and 191 from throat cultures of healthy individuals) by both phenotypic and molecular techniques. Almost all patient isolates were assigned to three hyper-virulent lineages (ET-5 complex, ET-37 complex and cluster A4) by both multilocus enzyme electrophoresis (MEE) and pulsed-field gel electrophoresis (PFGE). In contrast, MEE and PFGE assigned 20% and 15% respectively of carrier isolates to the hyper-virulent clones (4% for both methods together). There was also a higher correlation between PFGE and phenotypes associated with virulent clones. These notable differences between the two molecular methods were further observed in more than half the carrier isolates, suggesting that the associations between these strains were distorted by recombination events. However, almost one-third of total endemic strains from symptom-free carriers and almost all patient strains belonged to clones defined by MEE and PFGE, with no known epidemiological connection. These data indicate low transmission and a weak clonal structure for N. meningitidis.

In Victoria between 1990 and 1996, meningococcal infections occurred in 1–2/100000 people each year, with sometimes devastating outcome. In 1997, a typical year, we conducted a case-control study of all cases notified to the State Disease Control Unit, to investigate personal, environmental and lifestyle risk factors. In bivariate analysis many exposures were statistically significantly different (at P = 0·01) in cases and controls. The level of risk, and specific risks, differed between children (under 16) and adults (16 years and over). In multivariate analysis few exposures remained significant (at P = 0·05). However, these included having a smoker amongst close contacts, exposure to construction dust, recent illness, a history of snoring and speech problems, and sharing a bedroom. Besides confirming some previously identified risk factors, this is the first time that snoring and speech problems have been identified as risk factors for meningococcal disease.

We examined the use of polymerase chain reaction (PCR) in investigating suspected cases of meningococcal infection in Birmingham. Data held by Birmingham Health Authority were interrogated to determine cases of suspected or confirmed meningococcal infection for a 3-year period from April 1996. The microbiology departments of five local hospitals completed a standard proforma about the microbiological investigation of cases and included details of patient age, clinical presentation and method of confirmation of the clinical diagnosis. Of 273 cases, 123 had PCR performed on either cerebrospinal fluid and/or blood. Groups more likely to have a PCR done were those presenting with septicaemia alone, and those in the 5–14 year age group. In 33 cases, PCR was the only positive microbiological result. Over the study period there was increasing but variable use of PCR in the investigation of meningococcal infection and PCR increased the yield of confirmed cases.

Legionnaires' disease is an uncommon but important cause of life-threatening community-acquired or nosocomial pneumonia. The urinary antigen enzyme immunoassay test, used in Victoria since 1995, now accounts for the majority of initial laboratory notifications (81% in 1999). We review the impact of the test on the disease epidemiology and the public health investigative process. We focus on the major subgroup of cases due to Legionella pneumophila serogroup 1, comparing delays until notification and mortality for urinary antigen detected cases with culture detected cases. The urinary antigen test facilitates a 5-day reduction for the delay between onset of illness and notification. We observed that there was minimal clinical heterogeneity of urinary antigen detected cases whether they were subsequently culture confirmed or not. We encourage clinician use of the urinary antigen test in cases of community-acquired pneumonia where Legionnaires' disease is a possible diagnosis, in conjunction with culture of clinical specimens.

The objective of this study is to estimate the measles reproduction ratio for eight Western European vaccination programmes. Because many plausible age-structured transmission patterns result in a similar description of the observations, it is not possible to estimate a unique value of the reproduction ratio. A method is developed to estimate bounds and confidence intervals for plausible values of the reproduction ratios using maximum likelihood methods. Lower and upper bounds for plausible values of the basic reproduction ratio are estimated to be 7·17 (95% CI 7·14–7·20) and 45·41 (95% CI 9·77–49·57), corresponding to lower and upper bounds on critical vaccine coverage of 86·6% and 98·1%. Of the eight evaluated vaccination programmes, four have vaccine coverage below the lower bound and allow measles to persist, and four have vaccine coverage at the upper bound and may eventually eliminate measles.

To evaluate the impact of the 1998 Australian Measles Control Campaign on immunity to measles and rubella, 4400 opportunistically-collected sera, submitted to diagnostic laboratories across Australia from subjects aged 1–49 years, and 3000 from subjects aged 1–18-years, were tested before and after the campaign, respectively. The proportion of individuals aged 1–18 years who were immune to measles rose from 85% before, to 90% after, the campaign (P < 0·001). The greatest increase was in preschool (7%, P < 0·001) and primary school (10%, P < 0·001) children, who were actively targeted by the campaign. Rubella immunity in 1–18 year-olds rose from 83% to 91% (P < 0·001), again with significant increases in preschool (4%, P = 0·002) and primary school (16%, P < 0·001) children. 94% of individuals aged 19–49 years were immune to rubella. These serosurveys confirm other evidence of the effectiveness of the Australian Measles Control Campaign and demonstrate the value of serosurveillance using opportunistically collected sera.

Many countries are currently studying the possibility of mass vaccination against varicella. The objective of this study was to provide a comprehensive picture of the pre-vaccine epidemiology of the varicella zoster virus (VZV) to aid in the design of immunization programs and to adequately measure the impact of vaccination. Population-based data including physician visit claims, sentinel surveillance and hospitalization data from Canada and the United Kingdom were analysed. The key epidemiological characteristics of varicella and zoster (age specific consultation rates, seasonality, force of infection, hospitalization rates and inpatient days) were compared. Results show that the overall epidemiology of varicella and zoster is remarkably similar between the two countries. The major difference being that, contrary to Canada, the epidemiology of varicella seems to be changing in the United Kingdom with an important decrease in the average age at infection that coincides with a significant increase in children attending preschool. Furthermore, differences exist in the seasonality between the United Kingdom and Canada, which seem to be primarily due to the school calendar. These results illustrate that school and preschool contact patterns play an important role in the dynamics of varicella. Finally, our results provide baseline estimates of varicella and zoster incidence and morbidity for VZV vaccine effectiveness and cost-effectiveness studies.

We have evaluated the epidemiological evidence for an aetiological role of varicella zoster virus (VZV) infection in the development of multiple sclerosis (MS). A MEDLINE search of the English language literature for 1965–99 identified 40 studies. These studies were categorized as seroepidemiological (13), case-control (23), historical cohort (2) or ecological (2). One study used both case-control and historical cohort methodologies. Studies were then classified according to methodological rigour, using criteria derived from published guidelines for the epidemiological study of MS. There was a large variability in the quality of evidence. The five studies with the best methodology failed to show an increased risk of MS associated with varicella or zoster infections. At the present time there is insufficient evidence to support an important aetiological role of VZV infection in the development of MS.

A serological study of hepatitis A was carried out in low-income areas scheduled for a major sanitation programme in Rio de Janeiro, Brazil. Blood spots were collected by finger puncture and transported on filter paper, and total antibodies to hepatitis A virus were detected by ELISA. Households were also interviewed to collect information on their environmental conditions and socio-economic status. A generalized linear model using a complementary log–log function was fitted to the data, using the logarithm of age as an explanatory variable to derive adjusted rate ratios (RR). The risk of infection was greater among households with 2–3 members per room (RR = 1·4; 95% CI = 1·04–1·8) or more than three per room (RR = 1·5; 95% CI = 1·2–2·0). People living on hilltops (RR = 1·5; 95% CI = 1·02–2·2), near to open sewers (RR = 1·2; 95% CI = 1·03–1·5) or lacking a kitchen (RR = 1·4; 95% CI = 1·08–1·9) were also at greater risk than others. The number of taps and water-using fittings in the house was associated with a protective effect (RR = 0·9 for each tap; 95% CI = 0·9–0·98). A significant protective association was found with maternal education but not with gender or household income. The results do not suggest a strong association with water quality. Ownership of a ceramic water filter was associated with a protective effect on the margin of significance, but the practice of boiling drinking-water was not, nor was the type of water source used. The results suggest that that the risk of infection with hepatitis A is determined by environmental variables in the domestic and public domains.

In Palestine, there has been an increase in the reported incidence of acute hepatitis A virus (HAV) infection since 1995. Since overt clinical disease occurs only among adults, questions were raised whether or not a shift in the epidemiology of HAV has occurred. This is generally characterized by a decrease in the overall incidence rate and a shifting in the mean age of infection towards adolescence and early adulthood. The need for a vaccination programme is being discussed. To resolve this issue, we examined the prevalence of anti-HAV in a representative sample of 396 school children in the Gaza Strip. The prevalence of anti-HAV was 93·7% (95% CI: 91·3, 96·1%). Stratifying the prevalence by age showed that 87·8% (95% CI: 78·6, 97%) were HAV antibody positive by the age of 6. By the age of 14, almost 98% (95% CI: 92·7, 100%) were HAV antibody positive. This means that the majority of HAV infection is still taking place in early childhood, when it is usually asymptomatic and of little clinical significance. The results refuted the shifting epidemiology theory and we recommend that a vaccination programme against HAV infection is not yet needed. Alternative explanations for the increase in reported cases are discussed.

To improve our knowledge for future hepatitis A virus (HAV) vaccination strategies we carried out a multicentre study on naturally acquired immunological protection against HAV in patients with chronic hepatitis in Italy. We enrolled 830 consecutive patients with chronic hepatitis on their first observation at one of the six Italian liver units participating in the study. Six hundred and fifty-eight patients (79·3%) were positive for total anti-HAV and 172 (20·7%) were negative. The anti-HAV negative patients were younger (median age 33, range 11–78) than the anti-HAV positive (median age 56, 18–87). There was a higher prevalence of cases with circulating anti-HAV among the 508 patients residing in southern Italy than in the 322 residing in northern Italy (88·8% vs. 64%, P < 0·001). No significant difference in the anti-HAV prevalence was observed between patients from northern Italy and those from southern Italy aged 0–30 years or in those over 60 years, while in those 31–60 years old there was a higher prevalence of anti-HAV positive patients from southern Italy (90·2% vs. 65·8%, P < 0·0001). Of the patients with liver cirrhosis in this study, only 3 of the 26 (11·5%) from northern Italy and 8 of the 228 (3·5%) from southern Italy had no immunological protection against HAV infection. The data suggest that the number of patients with chronic liver disease without naturally acquired immunity against HAV is substantial in Italy, particularly in the north of the country, and that new vaccination strategies are needed.

Our objectives were to assess the prevalence of anti-hepatitis A (HAV) antibodies in Spanish travellers to developing countries and to carry out a cost analysis to allow the comparison of two vaccination strategies. Adult subjects were selected from among travellers to developing countries. Information was obtained on age, sex, destination, previous vaccination against HAV and having received immunoglobulin. Blood specimens were obtained for anti-HAV antibody determination. A total of 485 travellers were studied. The prevalence of anti-HAV antibody was 30·5% (95% CI 26–35). Antibody prevalence was inversely correlated with age: 9·8% in 18–25 years of age, rising to 75·4% in those 41–55 years of age. Cost analysis determined that the critical value of prevalence for vaccination with HAV vaccine was 37·5%. It was concluded that the youngest Spanish travellers lack anti-HAV antibodies. Vaccination without screening in those [les ] 35 years of age and screening before vaccination for those > 35 years, are the preferred alternatives.