Previous studies showed differences in in vitro heterophil function between parental (A>B) broilers and F1 reciprocal crosses (D>C). Our objectives were to (1) determine if in vitro variations translate to differences in resistance to Salmonella enteritidis (SE) and (2) quantitate cytokine mRNA in heterophils from SE-infected chicks. One-day-old chicks were challenged and organs were cultured for SE. Chicks with efficient heterophils (A and D) were less susceptible to SE compared to chicks with inefficient heterophils (B and C). Heterophils were isolated from SE-infected chicks and cytokine mRNA expression was evaluated using quantitative real-time RT–PCR. Pro-inflammatory cytokine mRNA was up-regulated in heterophils from SE-resistant chicks compared to susceptible chicks. This is the first report to quantitate cytokine mRNA in heterophils from SE-infected chicks. These data show a relationship between in vitro heterophil function, increased pro-inflammatory cytokine mRNA expression, and increased resistance to SE in 1-day-old chicks.

Epidemiology and modelling are currently under pressure to build consistent scenarios of control in case of deliberate release of biological weapons. In order to assess the key parameters for the control of a smallpox outbreak in a large city (2 million inhabitants), we built a stochastic model to simulate the course of an epidemic controlled by ring vaccination and case isolation. Assuming a reference scenario with 100 index cases and implementation of intervention 25 days after the attack, the model forecasts an epidemic of 730 cases with an epidemic duration of 240 days. Setting intervention 20 days later would result in an almost fourfold increase in the epidemic size. A multivariate sensitivity analysis has selected three key parameters: the basic reproduction number (i.e. the number of secondary cases infected by one case in an entirely susceptible population, equal to 3 in the reference scenario), time to intervention, and proportion of traced and vaccinated contacts.

Australia experienced a resurgence of pertussis in the 1990s despite improved vaccine coverage. Although much of the increase was attributable to increased detection of cases in older persons with waning immunity by serology, vaccine changes or alterations in circulating Bordetella pertussis strains may also have contributed. We determined the frequency of variants of B. pertussis pertactin (prn), and pertussis toxin subunit 1 (ptxS1) genes, restriction fragment length polymorphism (RFLP) types and fimbrial serotypes prevalent in Australia prior to, and during the 1990s. Ampoules of the whole-cell vaccine in use prior to 1999 and 84 B. pertussis isolates stored between 1967 and 1998 by laboratories around Australia were analysed. One pertactin allele, Prn3, not detected before 1985, was found in 24 out of 57 (42%) isolates between 1989 and 1998 (P<0·0001). PtxS1A was found in all isolates. IS1002 type 29, found in 17 out of 31 (55%) isolates tested, was the predominant RFLP type. The only difference in fimbrial serotype distribution between the time-periods was an increase in serotype 3 (P=0·054). The whole-cell vaccine contained only the alleles prn1 and ptxS1A. Antigenic shift in B. pertussis may have contributed to the re-emergence of pertussis in Australia. Monitoring these trends will be important as acellular vaccines are introduced and changes are made to pertussis vaccine schedules.

Severe acute respiratory syndrome (SARS) has emerged as a new respiratory disease caused by a novel coronavirus and is associated with substantial morbidity and mortality [1, 2]. Dynamic mathematical models have suggested that SARS, if uncontrolled, would infect the majority of people wherever it was introduced [3–5]. The patterns of spread suggest droplet or contact transmission [6]. Close proximity of persons enhances the risk of transmission, and this together with handling of human secretions (respiratory secretions, faeces, etc.) have made the hospital setting particularly vulnerable to the rapid spread of SARS.

On 6 November 2001, a possible case of leptospirosis was notified in a canoeist following a white-water event on the River Liffey. It emerged that a second race participant was also a possible case. An outbreak control team coordinated the epidemiological investigation, laboratory investigation, environmental assessment, communication and control measures. A cluster of six laboratory-confirmed cases of leptospirosis, serologically Leptospira interrogans serogroup Icterohaemorrhagiae was found. The attack rate was 9·2% (6/65). Fever, chills, red eyes and shortness of breath were significantly associated with being a confirmed case. Five cases were hospitalized. Swallowing more than one mouthful of water was associated with an increased risk of developing leptospirosis. Increased rainfall and release of hydroelectric water may have contributed to this outbreak. A multidisciplinary approach and use of the Internet and e-mail facilitated rapid and effective communication.

F4+ Escherichia coli is an important agent of post-weaning diarrhoea in piglets. Piglets that express an adhesion site for F4+ E. coli in their small intestine (F4R+) shed higher numbers of F4+ E. coli than piglets lacking this site (F4R−). We hypothesized that F4R+ piglets are more infectious and more susceptible for F4+ E. coli. This implies that in populations with F4R+ and F4R− piglets, the transmission would be dependent on the frequency of both types of animals. To quantify the difference in infectiousness and susceptibility, a one-to-one transmission experiment was performed with 20 pairs consisting of one inoculated and one contact piglet. Based on the contact infections observed, transmission parameters were estimated with generalized linear models. F4R+ piglets were infectious for other piglets and the reproduction ratio (R0) for homogeneous F4R+ populations, that is the average number of secondary infections that one F4R+ pig will cause during its entire infectious period in a population of susceptible F4R+ individuals only, was estimated as 7·1. F4R+ piglets were more susceptible than F4R− piglets and reducing the fraction of F4R+ piglets of a population will reduce transmission. It was calculated that in order to prevent major outbreaks of F4+ E. coli (R0<1), the fraction of F4R+ piglets must be lower than 0·14.

This paper describes the epidemiology of a syphilis outbreak in remote Australia, and explores contributing factors and control strategies. Between 1 August 2000 and 31 January 2002, 74 cases of early syphilis (42 female, 32 male) were identified in 73 Kimberley residents. Syphilis rates in age groups 10–19 and 20–29 years were 583 and 439 per 100000 person years respectively. Factors contributing to the outbreak included incompleteness of sexually transmitted infection (STI) clinical management, untimely contact tracing, staffing and management issues, and poor community knowledge about STIs. Outbreak control strategies addressed factors that could be influenced by changes in health service delivery, and focused on providing education and support to health staff, and efforts to increase community knowledge about sexual health. Although some improvements have occurred, the outbreak is still continuing. Until open and honest discussion and a collaborative approach is taken toward STI problems affecting Indigenous Australians, outbreaks such as this will continue to occur.

This study measured the prevalence and the risk factors associated with HCV antibody-positive prisoners. A total of 630 prisoners completed a questionnaire about risk behaviours associated with HCV transmission and were tested for HCV antibody from a blood test. Of these 362 (57·5%) prisoners were HCV antibody positive. A total of 436 (68·8%) prisoners reported ever injecting drugs and 332 reported injecting drugs in prison. HCV-positive prisoners were more likely to have injected drugs (OR 29·9) and to have injected drugs in prison during their current incarceration (OR 3·0). Tattooing was an independent risk factor for being HCV positive (OR 2·7). This is the first study conducted on prisoners that has identified having a tattoo in prison as a risk factor for HCV. Injecting drugs whilst in prison during this incarceration was also a risk factor for HCV. Our results show prisoners who injected drugs outside of prison continue to inject in prison but in a less safe manner.

Cases of gastroenteritis were examined to identify if dietary intake prior to an episode and food-handling and storage practices in the home were risk factors for illness. Cases and controls completed a dietary questionnaire after an event or when well, and questionnaires concerning food-handling, storage and general food-hygiene practices. Comparing cases to themselves when well, subjects were more likely to have eaten cold sliced salami, fried rice and foods cooked elsewhere, and to have had a baby in nappies in the house (OR 1·52–6·24, P[les ]0·01). Cases compared to non-cases were more likely to have bought frozen poultry, have eaten foods cooked elsewhere and to have had a baby in nappies in the house (OR 1·44–2·05, P[les ]0·01). Although food-handling and storage practices are considered important, we were unable to detect an association in this study.

The aim of this study was to assess the demographic factors and pattern of injuries sustained by nurses, and to determine the occupational hazard of exposure to hepatitis B (HBV) and C (HCV) viruses among nurses. The study involved 906 hospital-based nurses working in three large hospitals. Between August 2002 and January 2003 a total of 595 practising nurses were accepted for inclusion. The results of questionnaires completed were collated and χ2 and ratios were used for analysis. Of the 595 nurses, 111 (18·7%) had evidence of previous or current HBV infection and 32 (5·4%) of HCV infection. We found that 11·2% of the nurses who had worked for a period of between 0 and 5 years and 37·1% of those who had worked for a period between 16 and 20 years had evidence of HBV or HCV infection. Of the nurses working in surgical clinics, 59·4% had evidence of previous HBV or HCV infection and those working in hospital clinics had an 18·2% infection rate. Of the nurses occupationally exposed to HBV and HCV infections, 22·4% had received sharps injuries from apparatus and 63·6% had suffered needlestick exposure. Findings also showed 2·7% HBsAg positivity and 5·4% anti-HCV positivity. Of the 452 (76%) nurses who faced the occupational hazard of exposure to hepatitis infections, 27·7% (125/452) had not been vaccinated against HBV. Nurses working in our health-care sector are frequently exposed to occupational exposure for HBV and HCV infections. In order to prevent the infection of nurses with hepatitis, we advocate precautions and protection from sharps injuries. A programme of education, vaccination and post-exposure prophylaxis must be implemented.

Serological surveys among representative population samples have proved rare given their reliance on invasive sample collection. We therefore completed the first population-based postal survey of immunity in England and Wales using new oral fluid technology. This paper examines the feasibility of this new methodological approach. Nearly 5500 oral fluid samples were collected, with individual demographic and social data via a questionnaire, from persons under 45 years of age recruited through general practices. Instructions were accurately followed with only 1% of samples returned without risk-factor data. The overall response rate was 40%. Response was independently associated with age, sex and location. Response was highest in children aged 5–14 years, adult females and in rural locations. This approach allowed the successful collection of comprehensive individual risk data, but response rates in adults must be improved if oral fluid surveys are to routinely complement serological surveillance.

A case-control study was conducted in a brucellosis low-prevalence area of NW Spain to determine factors associated with high within-flock small-ruminant brucellosis prevalence in 1998. Forty-one cases and 69 controls were selected and information from both official sources and personal interviews was retrieved for every flock. The relationship between variables obtained and flock status was assessed by unconditional multivariable logistic regression analysis. The introduction of replacement animals into the flock, the presence of older farmers, an inadequate brucellosis vaccination programme and higher flock seroprevalence in the town in 1997 were positively associated with case flocks. Thus, specific actions directed at farms presenting these characteristics should be included within official eradication programmes. In addition, for the 1999 campaign the time from sampling to culling the seropositive animals correlated positively (r=0·53; P<0·01) with the flock seroprevalence the following year, suggesting the need for a faster removal of the infected animals to increase the efficacy of the eradication campaigns.

To estimate the magnitude and distribution of self-reported, acute gastrointestinal illness in a Canadian-based population, we conducted a retrospective, cross-sectional telephone survey of approximately 3500 randomly selected residents of the city of Hamilton (Ontario, Canada) from February 2001 to February 2002. The observed monthly prevalence was 10% (95% CI 9·94–10·14) and the incidence rate was 1·3 (95% CI 1·1–1·4) episodes per person-year; this is within the range of estimates from other developed countries. The prevalence was higher in females and in those aged <10 years and 20–24 years. Overall, prevalence peaked in April and October, but a different temporal distribution was observed for those aged <10 years. Although these data were derived from one community, they demonstrate that the epidemiology of acute gastrointestinal illness in a Canadian-based population is similar to that reported for other developed countries.

An environmental surveillance programme was developed to determine whether water supplies could be a source of Burkholderia pseudomallei as noted during previous melioidosis outbreak investigations. Water supplies to communities in the three northern Australian jurisdictions (Western Australia, Northern Territory and Queensland) were sampled periodically during 2001 and 2002. Water and soil samples were collected from communities known to have had recent culture-positive melioidosis cases and nearby communities where no cases had been diagnosed. Clinical isolates of B. pseudomallei obtained from northern Australian patients during 2001 and 2002 were compared with the environmental B. pseudomallei isolates by ribotyping and pulsed-field gel electrophoresis. B. pseudomallei was isolated from 11 distinct locations, all in the Northern Territory, seven of which were associated with culture-positive melioidosis cases (>1 case at three locations). Water was implicated as a possible environmental source of melioidosis in six locations. A variety of free-living amoebae including Acanthamoeba and Hartmannella spp. that are potential hosts to B. pseudomallei were recovered from environmental specimens. Culturable B. pseudomallei was not found to be widely dispersed in the environments sampled.

This is a surveillance study of the antimicrobial resistance of the S. flexneri group in the context of its serotype diversity. It includes 1422 isolates, which were sent to the National Shigella Reference Centre (NSRC) by hospitals and outpatient clinics in Israel during a 3-year period (2000–2002). The strains were identified and classified according to the prevalence and antigenic structure of their serotypes. All samples were checked for resistance to ampicillin (AMP), trimethoprim–sulphamethoxazole (TMP–SMX), ceftriaxone (CRO), tetracycline (TE), nalidixic acid (NAL), and chloramphenicol (C) by the disk diffusion method of Bauer et al. There were significant differences in their resistance to the individual antimicrobials with resistance to AMP, TE and C being lower among the strains of serotype 6 than among those of serotypes 2a and 1b. The resistant phenotypes were also serotype-specific. The similarities both in individual and in phenotype resistance between the rare and the prevalent serotypes (but not serotype 6) may be attributed to their antigenic relatedness. The serospecificity of the antimicrobial resistance was not affected by external factors such as seasonality and source (hospital or outpatient laboratory) of the isolates, and the age and sex of the patients. The serotype-specific approach can assist in properly assessing the problem of the antimicrobial resistance of the Shigella flexneri group and may prove useful for the empirical therapy of shigellosis. The observed interdependency between resistance and the antigenic specificity and relatedness of the S. flexneri serotypes requires additional investigation.

Each year, countries that participate in the European Surveillance Scheme for Travel Associated Legionnaires' Disease (EWGLINET) are requested to complete a set of standardized reporting forms that provide epidemiological and microbiological information on the total number of cases (non-travel as well as travel-related cases) detected in their country. Trends at the national and aggregated European level have been analysed for 2000–2002. For this period, 10322 cases of Legionnaires' disease were reported and national infection rates ranged from 0 to 34·1 cases per million population. A total of 189 outbreaks were associated with nosocomial infection, community exposure or travel. The upward trend in diagnosis through the urinary antigen detection test has resulted in a higher ascertainment of cases in many countries. However, the decline in diagnosis by culture of the organism is likely to severely hamper outbreak investigations in the future if fewer clinical isolates are available for matching with environmental isolates. This important data-set has been used for studying the effectiveness of surveillance and legionella control and prevention programmes within Europe.

Discharge information for all Hong Kong government hospitals, which is routinely collected through the Clinical Management System (CMS), was used to assess the relative importance of all causes of diarrhoeal illness and to address the issue of under-diagnosis of rotavirus by linking discharge diagnostic codes with actual laboratory results for one hospital. Of all children less than 5 years of age hospitalized in Hong Kong in the 2-year period July 1997 to June 1999, 12257 (11%) were discharged with a primary diarrhoea diagnosis (74% coded as non-specified, 10·4% as rotavirus, 11% as Salmonella and 5% as other viral or bacterial). Linked laboratory and discharge data for one hospital demonstrated that 15% (n=1522) of all admissions had a primary diarrhoea diagnosis and that 40% of these had a specimen sent for rotavirus testing, of which 37% were positive. However, 46% (67/145) of children with a diagnosis of rotavirus infection had no virology result, and 69% (172/248) of positive rotavirus results were in children with no diagnosis indicating rotavirus infection. Modification of the CMS to routinely combine existing computerized laboratory data with the CMS discharge diagnoses and to develop mechanisms to enhance reliability of discharge diagnosis coding could produce a powerful resource for disease surveillance, auditing and for monitoring the impact of future vaccination and other prevention programmes.

We did a retrospective study of 1920 episodes of community-acquired pneumonia (CAP) in 27 community hospitals and analysed inter-hospital variability in length of hospital stay (LOS), mortality and readmission rates. The overall adjusted LOS (mean±S.D.) was 10·0±9·8 days. LOS increased according to the Pneumonia Severity Index (PSI) risk class: 7·3 days for class I to 11·3 days for class V (P<0·001). In a multiple regression model, LOS increased (P<0·001) according to the hospital (inter-hospital variability), PSI risk class, complications during hospitalization, admission to ICU, need of oxygen and transfer to a nursing home. Hospitals with shorter LOS did not show an increased readmission rate (adjusted OR 1·02, 95% CI 0·51–2·03, P=0·97) and post-discharge mortality (adjusted OR 1·20, 95% CI 0·70–2·05, P=0·51). There are significant inter-hospital variations in LOS in patients with CAP which are related to differences in clinical management. The reduction of these differences will further improve efficiency and quality of care.

The presumptive treatment of parasitosis among immigrants with albendazole has been shown to save both money and lives, primarily via a reduction in the burden of Strongyloides stercoralis. Ivermectin is more effective than albendazole, but is also more expensive. This coupled with confusion surrounding the cost-effectiveness of guiding therapy based on eosinophil counts has led to disparate practices. We used the newly arrived year 2000 immigrant population as a hypothetical cohort in a decision analysis model to examine the cost-effectiveness of various interventions to reduce parasitosis among immigrants. When the prevalence of S. stercoralis is greater than 2%, the incremental cost-effectiveness ratios of all presumptive treatment strategies were similar. Ivermectin is associated with an incremental cost-effectiveness ratio of $1700 per QALY gained for treatment with 12 mg ivermectin relative to 5 days of albendazole when the prevalence is 10%. Any presumptive treatment strategy is cost-effective when compared with most common medical interventions.

In order to target the most important cost components of gastroenteritis in The Netherlands and to indicate which change of policy yields the largest decrease in costs, the cost of illness of gastroenteritis and the number of Disability Adjusted Life Years (DALYs) in the Dutch population in 1999 were determined. The costs of gastroenteritis were estimated using data mainly from a community-based cohort study. For calculating DALYs, data on the number of deaths due to gastroenteritis were used from Statistics Netherlands. On average, the costs for gastroenteritis were 77 Euro (€) per case. For all patients in The Netherlands, the costs were estimated at €345 million (ranging between €252 and €531 million). Indirect costs made up 82% of this total. An estimate of costs for patients with campylobacter, salmonella or norovirus infections was, in total, 10–17% of the costs of gastroenteritis. Gastroenteritis was associated with a loss of approximately 67 000 DALYs.