A case control study comprising 282 cases and 319 matched controls was conducted in Denmark during 1996–7. Two estimates of the odds ratio (OR) were determined for each risk factor with and without ‘protective factors’ fitted into the final model. Consumption of undercooked poultry (OR 4·5; 8·2), consumption of red meat at a barbecue (OR 2·3; 4·1), consumption of grapes (OR 1·6; 2·8) and drinking unpasteurized milk (OR 2·3; 11·8) were identified as risk factors in both models. Frequent consumption of pork chops (OR 4·4) and daily contact with domestic animals and pets were identified as risk factors in one of the two models only. Finally, foreign travel was found to be a significant risk factor (OR 2·5). Seasonal and regional interaction was observed for several risk factors and the time elapsed from interviewing of cases to interviewing of controls seemed to influence the effect of certain seasonal dependent risk factors.

Despite being the commonest bacterial cause of infectious intestinal disease (IID) in England and Wales, outbreaks of campylobacter infection are rarely reported. However, data from the Campylobacter Sentinel Surveillance Scheme suggested that outbreaks might be more common than was previously suspected, since a high proportion of cases reported other illness in the home or in the community at the same time as their illness. To identify factors that might lead to these apparent outbreaks, the exposures of cases of Campylobacter jejuni infection reporting other illness, either in the home or the community, were compared with those for cases not reporting other illness using case–case methodology. Illness in the home was associated with consuming organic meats in the winter, having contact with a pet suffering from diarrhoea or visiting a farm in the 2 weeks before the onset of symptoms. Illness in the community was associated with the consumption of foods in restaurants or drinking unpasteurized milk. Prevention of campylobacter infection requires that better methods of outbreak detection and investigation are developed, which in turn should lead to a better understanding of risk factors.

Sixty-six broiler flocks were sampled to determine the presence of Campylobacter spp. at slaughter in 1998. Thirty flocks (45%) tested positive and C. jejuni was identified in all isolates. Combined pulsed-field gel electrophoresis/amplified fragment length polymorphism (PFGE/AFLP) subtyping of 177 isolates from 24 positive flocks revealed 62 subtypes; 16 flocks harboured more than one subtype. When subtyping 101 clinical C. jejuni isolates collected in the same time period and area, 60 PFGE/AFLP types were identified. Comparison of subtypes from poultry and human isolates revealed three shared PFGE/AFLP types, which were present in 11 human isolates. Fifty per cent of all poultry isolates and 39% of all human isolates were resistant to ciprofloxacin. The present study confirms the increase in ciprofloxacin resistance in both human and poultry C. jejuni isolates in Austria, as observed in several countries worldwide. A small number of human isolates shared PFGE/AFLP types with poultry isolates, however, further studies should also focus on the identification of other sources of C. jejuni infection in humans.

An outbreak of salmonellosis, involving cases of infection with Salmonella enteritidis phage types (PT) 5c and 6a, occurred across Scotland between May and August 2000. In total, 70 outbreak cases were microbiologically confirmed. Preliminary investigation suggested that consumption of food, especially chicken dishes, from Chinese restaurants or take-aways (food businesses) was a risk factor for infection. A matched case-control study demonstrated a statistically significant association (OR 22·4, P=0·0024) between infection and consumption of food from Chinese food businesses. A cohort study of novel design suggested that chicken was an important vehicle of infection. However the result did not reach statistical significance (OR 1·7, P=0·3). Extensive environmental investigation was unable to identify the source of the suspected contaminated chicken.

We collected diarrhoea specimens in two hospitals in southern Thailand in 1999 to examine whether infection by the Vibrio parahaemolyticus pandemic clone is prevalent. V. parahaemolyticus was isolated from 317 specimens. Seventy-six per cent of the isolated strains had the pandemic clone-specific characteristics (tdh+, trh−, and an unique toxRS sequence detectable by GS-PCR) and an associated characteristic (the ORF8 sequence of f237 phage). These strains belonged to the three pandemic servovars with the O3[ratio ]K6 strains being dominant and three other serovars (O1[ratio ]K25, O1[ratio ]K41 and O4[ratio ]K12). We also found O1[ratio ]K25 and O1[ratio ]K41 strains with the pandemic clone-specific characteristics among the strains isolated from the international travellers who left Thailand and three other Asian countries between 1998 and 1999, verifying pandemic potential of these strains. The results demonstrate prevalence of infection by the pandemic clone in southern Thailand and suggest emergence of various serovariants in this area and their implication in international spread.

This study was conducted to determine the molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in Malaysian hospitals. A total of 264 MRSA isolates from eight hospitals were subjected to typing by pulsed-field gel electrophoresis (PFGE) of SmaI restricted DNA. Antibiotic disk susceptibility testing was also carried out to determine their resistance patterns. Thirty-one PFGE pattern types were identified. Three major pattern types A, ZC and K were found with type A the predominant profile in c. 80% of strains and present in all hospitals. Unlike type A, other DNA pattern types were unique to the hospitals in which they were isolated. PFGE type A also consisted of strains that were multiply antibiotic resistant. The presence of a single predominant PFGE type in Malaysian hospitals is an important finding which suggests that inter-hospital spread of MRSA had occurred frequently and regularly.

To quantify the host genetic component of meningococcal disease (MD) susceptibility, the sibling risk ratio (λs) was calculated as the ratio of observed MD cases among 845 siblings of 443 UK Caucasian cases to that expected, calculated from age-calendar year specific rates for England and Wales. Twenty-seven siblings contracted MD compared with an expected 0·89, generating a λs value of 30·3. Overestimation of λs due to Neisseria meningitidis exposure was minimized by excluding siblings with MD onset within set time points of the index case. Irrespective of whether siblings contracted MD more than 1, 3, 6, 9 or 12 months after the index case, the λs varied slightly (λs range: 8·2–11·9), suggesting that host genetic factors may contribute approximately one third of the total λs. Social class distribution did not differ between MD cases and the general population of England and Wales. This study is the first to calculate λs for MD and establishes that susceptibility to MD has a significant host genetic component.

A mathematical model is described which determines the impact of a schedule of vaccination on the time course of a certain class of diseases. The data are the demographic variables and parameters and age-dependent non-fatal and fatal case rates. Given the age- and time-dependent rates of vaccination including coverage and corresponding efficacies, various schedules may be distinguished by either the absolute numbers of cases and deaths avoided or the numbers of cases and deaths avoided per dose of vaccine. The model was applied to meningo-coccal serogroup C disease in France. The outcomes of six different vaccination schedules were examined. In absolute terms, a schedule in which all individuals aged between 2 and 20 years were vaccinated performed best, but this schedule and that in which only 1-year olds were vaccinated performed equally and best in terms of cases prevented, but not lives saved, per dose.

Results of the Dutch laboratory surveillance of bacterial gastroenteritis between 1991 and 2001 are presented and compared with recent findings in general practices and in the community. Between 1996 and 2000 the mean annual number of stools screened by sentinel laboratories was about 1000 samples/100000 inhabitants, which is 4% of the estimated annual incidence of gastroenteritis in the Dutch population. Campylobacter (36/100000 inhabitants) and salmonella (24/100000 inhabitants) were the main pathogens isolated. Since 1996, the incidence of laboratory confirmed salmonellosis decreased by 30%, predominantly among young children. The incidence of campylobacter was highest in urban areas and Salmonella Enteritidis emerged as the predominant serotype in urban areas. Between 1991 and 2001, multi-resistant Salmonella Typhimurium DT104 emerged to comprise up to 15% of all salmonella isolates in 2001. Reported rates of Shigella spp. and Yersinia spp. varied little, with average annual incidences of 3·2 and 1·2 cases/100000 inhabitants, respectively. Escherichia coli O157 (90% STEC) was scarcely found (0·26/100000).

The aim of this study was to determine the prevalence of gastroenteritis among children aged 4 years in South Australia. A cross-sectional survey of 9543 South Australian children aged 4 years was undertaken. Parents completed a questionnaire on behalf of their child who had attended a pre-school health check in 1998. The questionnaire covered gastrointestinal and respiratory symptoms experienced by the child in the previous 2 weeks and other risk factors for gastroenteritis. The 2-week prevalence of gastroenteritis among 4-year-old children was 14·2%. The major risk factors for gastroenteritis were presence of persons who had gastroenteritis inside the home, contact with persons who had gastroenteritis outside the home, antibiotic use and sore throat. Medical attention was sought for 20% of children who had gastroenteritis. Gastroenteritis is a significant cause of morbidity among young children and presents a considerable burden on the community. A substantial proportion of these occurrences of highly credible gastrointestinal symptoms may be manifestations of respiratory infections.

The sequelae of Infectious Intestinal Disease (IID) in a population-based sample of cases and matched controls were investigated for a period of 3 months following the initial infection. Incident cases of IID presenting to GPs or occurring in the community and controls were studied at 3 weeks and over a 3-month follow-up period. Cases were six times more likely than controls to have gastrointestinal symptoms, particularly diarrhoea, at 3 weeks. Ten per cent of cases consulted their GP in the 3 months after episode and 2·3% were referred to hospital. GP presentation rates were twice as high in cases. Gastrointestinal symptoms persist after IID, leading to an increased likelihood of GP consultation and hospital referral. Diagnosis of irritable bowel syndrome may be more likely following IID. The burden of IID is likely to be considerable given its high incidence and the frequency of such sequelae.

From 1 January 1992 to 31 December 2000, 27 milkborne general outbreaks of infectious intestinal disease (IID) were reported to the Public Health Laboratory Service (PHLS) Communicable Disease Surveillance Centre (CDSC). These outbreaks represented a fraction (2%) of all outbreaks of foodborne origin (N=1774) reported to CDSC, but were characterized by significant morbidity. Unpasteurized milk (52%) was the most commonly reported vehicle of infection in milkborne outbreaks, with milk sold as pasteurized accounting for the majority of the rest (37%). Salmonellas (37%), Vero cytotoxin-producing Escherichia coli (VTEC) O157 (33%) and campylobacters (26%) were the most commonly detected pathogens, and most outbreaks were linked to farms (67%). This report highlights the importance of VTEC O157 as a milkborne pathogen and the continued role of unpasteurized milk in human disease.

In England and Wales over the last 30 years there have been 25 reported outbreaks of infection, associated with private water supplies (PWS). The majority (16 outbreaks) were reported after the introduction of enhanced surveillance. Although PWS only serve 0·5% of the population, 36% of drinking water outbreaks are associated with PWS. The main pathogen, campylobacter, was implicated in 13 (52%) outbreaks. Most reported outbreaks (88%) occurred in commercial or Category Two supplies, which potentially affect larger populations. The main factors implicated in these outbreaks are temporary or transient populations, treatment (lack or failure), the presence of animals and heavy rains. The public health problem associated with PWS could be prevented by the identification and understanding of risk factors, by the proper protection of water sources and adequate treatment and maintenance. This could be facilitated through the introduction of a risk assessment as part of a scheme for PWS.

In the light of rising numbers of tuberculosis (TB) cases in the United Kingdom, the problem of anti-tubercular drug resistance remains a significant concern. Drug resistant TB cases are more difficult and costly to treat, and require appropriate treatment and control mechanisms. This matched case control study aimed to investigate risk factors for resistance in Leicestershire, using data for laboratory isolates of Mycobacterium tuberculosis identified from 1993 to 1998. Each case, defined as culture positive laboratory isolates resistant to at least one first-line drug, was matched to four fully sensitive controls on age, sex and ethnic group. Twenty-three cases and 81 controls were included in the analysis. Drug resistance in Leicestershire was found to be associated with poor adherence to treatment (OR 4·8, 95% CI 1·6–14·4, P=0·005) and with previous TB (OR 3·7, 95% CI 1·2–11·8, P=0·022). These findings emphasize the need to provide support to patients taking treatment in order to maximize adherence.

Bovine tuberculosis is a zoonotic disease that not only causes huge economic losses but also poses an important risk for human infection. The definitive identification of a clinical isolate relies on time-consuming, highly specialized and laborious biochemical tests. We have developed a method for the rapid and reliable identification of Mycobacterium bovis and for its simultaneous differentiation from other members of the M. tuberculosis complex. Furthermore, the technique also allowed us to distinguish M. tuberculosis complex members from other Mycobacterial species. The method comprises both a single PCR and a multiplex-PCR and can be confidently applied to samples of both veterinary and human origin.

Sixty-six cases of Q fever were diagnosed in people affiliated with a goat-farming co-operative in rural Newfoundland in the spring of 1999. Follow-up studies which included administration of the Short Form 36 Health Survey (SF-36) were conducted 3 and 27 months after the initial outbreak to prospectively follow the effects of acute Q fever on the quality of life of the participants. Twenty-seven months after the outbreak 51% of those who had Q fever reported persistent symptoms including seven participants whose symptoms had initially resolved 3 months after the outbreak. Individuals with Q fever had significantly lower scores on five of the eight scales in the SF-36 and lower scores in the mental and physical summary scales compared to uninfected controls. Although this supports the hypothesis of a ‘post Q fever fatigue syndrome’ (QFFS), further study is warranted.

The aim of the present study was to assess the prevalence as well as the possible risk factors of HIV, hepatitis B and hepatitis C, in 194 male prisoners who had been convicted for rape (n=105) or child molestation (n=89). HBsAg, HBeAg, anti-HBc, anti-HBs, anti-HCV and anti-HIV-1/2 were tested for. The participants also completed a standard sociodemographic questionnaire, indicating possible risk factors, the Barratt Impulsiveness Scale, and the life-time history of aggression. Anti-HIV antibodies were not found in any of the prisoners. HBsAg was found in 25 (13%), anti-HBc in 94 (49%), anti-HBs in 40 (21%) and anti-HCV in 13 (6·5%) subjects. Logistic regression analysis showed that anti-HCV positivity was associated with intravenous drug use (OR 20·7, 95% CI 1·1–4·9, P<0·001), while HBsAg positivity was associated separately with being foreign (OR 4·0, 95% CI 0·2–2·5, P<0·01), as well as with impulsiveness score (OR 1·06, 95% CI 0·01–0·11, P<0·02). The prevalence of HBV and HCV infection in this sex offender sample was highly increased in relation to the general population. Since it has been proved that sex offenders are a high-risk group for reoffending, monitoring their health is a necessary step towards prevention of sexually transmitted diseases being spread.

Hepatitis C virus (HCV) isolates from 93 patients living in Tunisia, including 16 haemophiliacs, were genotyped by INNO LiPA and partial sequencing of the 5′ untranslated region of the viral genome. In non-haemophiliacs, subtype 1b was largely predominant (79%), types 1a, 2a, 2b, 3a and 4a occurred much less frequently at 5, 7, 3, 3 and 1% of cases, respectively. In the group of haemophiliacs, a co-dominance between subtypes 1a and 1b was noticed (38%). Type distribution of HCV in Tunisia differs from that reported in other countries of the Mediterranean and Middle East regions. Genotyping results in respect of clinical status, age, and genotyping methods, are discussed.

We undertook a representative survey of measles antibodies in Addis Ababa, Ethiopia 1994, to characterize immunity and transmission. Specific-antibody levels (IU/l) were determined by ELISA for 4654 sera from individuals aged 0–49 years (1805 <15 years) collected by stratified household-cluster sampling. The proportion seronegative (<100 IU/l) was 20% (95% CI: 16–25) in children 9–59 months old, declining to 9% (7–12) in 5–9 year olds, 5% (4–7) in 10–14 year olds, and <1% in adults. The proportion of children (<15 years old) with low-level antibody (100–255 IU/l) was 8% (7–10). Vaccination and an absence of a history of measles illness were strongly associated with low-level antibody. History of measles vaccination in 9 months to 14-year-old children was ~80%. We estimate a primary vaccine failure rate of 21% (12–34) and continued high measles incidence of 22 per 100 susceptibles (19–24) per annum. Our data support the introduction of campaign vaccination in the city in 1998, although higher routine vaccine coverage is required to sustain the impact. The implications of a high prevalence of low-level antibody are discussed.

Co-circulating variants of influenza A/H3N2 viruses in children were studied in Houston, Texas between October 1997 and March 1998 to assess the effects of a new variant strain on the severity of clinical illness. Influenza A virus was isolated from the nasal wash or nasal aspirate specimens collected from children at two tertiary care hospitals, and 271 isolates were available for variant-specific subtyping using RT–PCR and restriction fragment length polymorphism (RFLP) analysis. We classified 124 (46%) influenza viruses as A/H3N2/Wuhan/359/95-like and 137 (50%) as A/H3N2/Sydney/05/97-like. Ten (4%) virus isolates could not be classified. Ill contacts in the household were reported more frequently in patients infected with A/Sydney-like viruses than in those infected with A/Wuhan-like viruses (85% vs. 71%, respectively, P=0·02). There were no differences in other demographic variables among children infected with these strains. This study found no increase in illness severity in children infected with a newly emerging strain.