Campylobacter species such as C. jejuni and C. coli are recognized as major causes of acute gastroenteritis world-wide. Although C. jejuni and C. coli are usually non-pathogenic in birds and animals, they cause enteric disease in humans and the source of infection is often the consumption of contaminated foodstuffs. In this paper we report on the development and use of a multiplex PCR of C. jejuni genomic DNA which yielded a PCR product with a unique polymorphic site that can be used to quickly and accurately identify and group C. jejuni isolates from any source including DNA, cell culture, skin washings and faecal samples. The test is simple and sensitive and can detect purified DNA from a single bacterium 102 cells from crude lysates, 103 cells in seeded faeces and 120 cells/ml of washing of 1 cm2 skin fragments of chicken skin.

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.

The objective was to evaluate foodborne outbreaks of undetermined aetiology by comparing them to pathogen-specific epidemiologic profiles of laboratory-confirmed foodborne outbreaks. National foodborne outbreak data reported to CDC during 1982–9 were categorized by clinico-epidemiologic profiles based on incubation, duration, percent vomiting, fever and vomiting to fever ratio. From the pathogen-specific profiles, five syndromes were developed: a vomiting-toxin syndrome resembling Bacillus cereus and Staphylococcus aureus; a diarrhoea-toxin syndrome characteristic of Clostridium perfringens, a diarrhaeogenic Escherichia coli syndrome, a Norwalk-like virus syndrome, and a salmonella like syndrome. Of 712 outbreaks, 624 (87·6%) matched one of five syndromes; 340 (47·8%) matched the Norwalk-like syndrome and 83 (11·7%) matched the salmonella-like syndrome. After combining information on known pathogens and epidemiologic profiles, only 88 (12·4%) outbreaks remained unclassified. Norwalk-like virus outbreaks appear as common as salmonella-like outbreaks. We conclude that profiling can help classify outbreaks, guide investigations and direct laboratory testing to help detect new and emerging pathogens.

We compared gastroenteritis cases that consulted a general practitioner (GP) with those who did not in a community-based study and also with those in a GP-based study. We aimed to identify factors associated with consultation, and with inclusion of cases by GPs, and secondly to study the effects on the frequency of detection of pathogens. Furthermore, we estimated the under-ascertainment by GPs. Both studies were performed in The Netherlands in the same population in an overlapping time-period. Overall, 5% of community cases consulted a GP. Cases who consulted suffered from more severe episodes than non-consulting cases. Inclusion of cases by GPs, instead of a study team, caused a selection of more severe cases with more chronic symptoms. When extrapolating data from GP-based studies, it should be taken into account that, in general practice, gastroenteritis due to bacteria and Giardia lamblia is a relatively large proportion of that in the community and gastroenteritis due to Norwalk-like viruses is a relatively small proportion. The incidence of gastroenteritis in general practices was estimated between 14 and 35 per 1000 person years.

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.

An unusually high incidence of Vibrio cholerae O1 infection was observed in southern Thailand between late December 1997 and March 1998. Fifty-seven V. cholerae O1 strains were isolated in five provinces during this epidemic and were examined. They were El Tor Ogawa strains exhibiting similar antibiograms. All strains were resistant to tetracycline, which had not been reported in Thailand since 1993. The ribotypes, hybridization patterns with ctx and zot gene probes, arbitrarily primed PCR profiles, and pulsed-field gel electrophoresis profiles of the representative strains were compared with the clinical strains isolated from patients in India and Bangladesh in 1997 and 1998 and from international travellers originating from various Asian countries during the 1992–8 period. All southern Thailand strains and the 1998 international traveller strain of Thai origin showed indistinguishable genetic fingerprinting patterns that were distinct from those of other test strains. The results suggest that a tetracycline-resistant clone newly emerged in late December 1997 caused the large epidemic in southern Thailand and that the variants with a slightly different antibiogram appeared during the course of the spreading epidemic.

The phenotypic and genotypic profiles of the V. cholerae strains causing the Mozambican 1997–8 epidemic were characterized to provide a reference for comparison with other epidemic strains. A total of 75 strains of V. cholerae O1 isolated in different provinces, were analysed. Strains were characterized by PCR for detecting toxin genes (ctxA, zot and ace), virulence associated genes (tcpA, nanH, hlyA and toxR) and ERIC sequences. All V. cholerae strains were serotype O1, Ogawa, biotype El Tor. MIC testing showed a high proportion of strains multi-resistant to drugs (100% to cotrimoxazole and 52% to tetracycline) and susceptibility to ciprofloxacin. The isolates contained two intact copies of the CTX genetic element and all other genes tested. PCR of restricted DNA revealed two ERIC types: the first in provincial isolates, also predominant in other African epidemic strains, and the second in Maputo isolates (the national capital).

Campylobacter infection has one of the highest rates of all the notifiable diseases in Australia, with a peak in children aged 0–35 months. A matched case-control study was conducted to investigate risk factors for campylobacter infection for children in this age group. Eighty-one cases and 144 controls were enrolled in the study that was conducted between 24 January 1996 and 21 January 1997. The following risk factors were found to be independently associated with illness: ownership of pet puppies (adjusted odds ratio [OR] 16·58, 95% confidence interval [CI] 3·73–73·65) and pet chickens (OR 11·80, CI 1·37–101·75), and consumption of mayonnaise (OR 4·13, CI 1·61–10·59). We propose that children aged less than 3 years are at risk of campylobacter infection if residing in a household which has puppies or chickens as pets.

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.

Nucleotide sequences of Shiga toxin (Stx) genes in STEC from various origins were determined and characterized by phylogenetic analysis based on Shiga toxin (Stx) with those deposited in GenBank. The phylogenetic trees placed Stx1 and Stx2 into two and five groups respectively, and indicated that Stx1 in sheep-origin STEC were placed into a different group from those in other STEC, and that Stx2 of deer-origin STEC also belonged to the unique group and appeared to be distantly related to human-origin STEC. On the other hand, Stx of STEC isolated from cattle, seagulls and flies were closely related to those of human-origin STEC. Such a diversity of Stx suggested that STEC might be widely disseminated in many animal species, and be dependent on their host species or their habitat. In addition, the active sites in both toxins were compared; the active sites in both subunits of Stx in all the animal-origin STEC were identical to those in human-origin STEC, suggesting that all the toxin of STEC from animals might be also cytotoxic, and therefore, such animal-origin STEC might have potential pathogenicity for humans.

Typhoid fever is endemic in the South Pacific. We investigated an outbreak in Nauru. Through interviews and medical records, we identified 50 persons with onset between 1 October 1998 and 10 May 1999, of fever lasting [ges ]3 days and one other symptom. Salmonella Typhi was isolated from 19 (38%) cases. Thirty-two (64%) patients were school-aged children, and 17 (34%) were in four households. Case-control studies of (a) culture-confirmed cases and age- and neighbourhood-matched controls; and (b) household index cases and randomly selected age-matched controls implicated two restaurants: Restaurant M (matched OR [MOR] = 11, 95% confidence interval [CI] = 1·3–96) and Restaurant I (MOR = 5·8, 95% CI = 1·2–29). Food-handlers at both restaurants had elevated anti-Vi antibody titres indicative of carrier state. The annual incidence was 5·0/l000 persons. Outbreak-associated costs were $46000. Routine or emergency immunization campaigns targeting school-aged children may help prevent or control outbreaks of typhoid fever in endemic disease areas.

The sources and transmission routes of sporadic Yersinia enterocolitica bioserotype 4/O:3 infections in Finland were studied. A total of 212 human strains were compared with 334 non-human strains, including 163 strains from pig slaughterhouses, 164 strains from retail outlets and 7 strains from pet animals. All strains were characterized using pulsed-field gel electrophoresis (PFGE) with NotI enzyme. When the 194 human and 287 non-human strains of 22 identical NotI profiles were further characterized with ApaI and XhoI enzymes, 126 genotypes (DI = 0·94) were distinguished. Of all 212 human strains, 80% were genetically indistinguishable from the strains found in samples of pig origin when characterized with the three enzymes. A major contamination source of sporadic Y. enterocolitica 4/O:3 infections was revealed to be edible pig offal: 71% of the human strains were indistinguishable from the strains isolated from tongues, livers, kidneys and hearts of pigs. These results reveal that in Finland contaminated pig offal is an important vehicle in the transmission of Y. enterocolitica bioserotype 4/O:3 from slaughterhouses to humans.

During outbreaks of Escherichia coli O157 a minority of patients with suspected infection develop haemolytic uraemic syndrome (HUS). The ability to identify this subgroup at an early stage is beneficial as mortality from HUS is high and may be influenced by intervention. During the 1996 Central Scotland E. coli O157 outbreak, of 886 patients from the community with suspected infection monitored at an outbreak clinic, nine developed HUS. We assessed factors associated with the development of HUS in this group. Children and the elderly were at increased risk of HUS. However, high white cell count was as least as good a predictor of HUS as age. High white cell counts predicted development of HUS with a sensitivity of 89%, specificity of 87%, positive predictive value of 7% and a negative predictive value of over 99%. We have used the results from this study along with other currently available evidence to propose a monitoring protocol for patients from the community with suspected E. coli O157 infection.

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.

We describe six meningococcal disease outbreaks that occurred in Angola during the period 1994–2000. In total, 7140 cases were documented. The age groups most affected were 15–29 years and 5–14 years; there were no differences in incidence between the sexes. Circulation of both serogroup A and sporadic serogroup B strains was demonstrated. Mass vaccination campaigns with A+C meningococcal polysaccharide vaccine were implemented, except in Yambala province in 1999 where insecure conditions precluded this intervention.

Outbreaks of serogroup A meningococcal disease in Angola may indicate an extension of these epidemics outside the meningitis belt. Mass vaccination campaigns stopped the Angolan epidemics within weeks. Civil conflict and displaced persons living in crowded areas created serious difficulties for surveillance and impeded timely public health responses.

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.

A cross-sectional survey was conducted to determine prevalence and assess risk factors for carriage of antibiotic resistant strains of Streptococcus pneumoniae in healthy school children in Hong Kong. Throat swabs were collected from 1455 subjects and written questionnaires providing demographic data and medical history were completed by parents. The overall carriage rate of Streptococcus pneumoniae was 3·5%, of which 49% were penicillin resistant. High levels of resistance to tetracycline (73%), erythromycin (52%), trimethoprim (66%) and ciprofloxacin (57%) were observed. Carriage was associated with presence of a younger sibling (OR = 1·79) and use of antibiotics (OR = 2·31). High use of day care and small size of housing units did not result in a high rate of carriage. The low rate of carriage may be linked to high use of antibiotics, geographical factors or ethnicity. High rates of antibiotic resistance reflect heavy use of antibiotics by general practitioners.

The aim of this study was to determine the prevalence of healthy Neisseria meningitidis pharyngeal carriers in a representative sample of the Catalonian school population, as well as its associated factors. The sample was divided into age groups: [les ]5, 6–7 and 13–14 years old. Parents were given a questionnaire to collect information on sociodemographic and epidemiological variables. Oropharyngeal swabs were collected with a cotton-tipped swab in an Amies transport medium and cultured on Thayer Martin plates at 35 °C in 5% CO2. The isolates were serogrouped and sero/subtyped. Of the 1406 children studied, 75 (5·34%) meningococcal carriers were detected: 63 B (4·5%), 9 non groupable (0·7%), 2 29E (0·1%) and 1X (0·07%). No serogroup C meningococci were found in this study, probably due to the high A+C vaccination coverage of up to 68·9% in children 6–7 years old. Bivariate analysis identified six statistically significant risk factors for meningococcal carriage: increasing age, recent upper respiratory tract infection, previous antibiotic treatment, number of students in the class, size of the classroom and social class. Multivariate analysis found that only age and previous antibiotic treatment remained statistically significant when the other factors were controlled.

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.