In England and Wales human salmonellosis is a major public health problem and, although mortality is low, the disease has important social and economic consequences. All surveillance indicators suggest that an epidemic of unprecedented proportions is occurring. Between 1081 and 1980 the number of strains received for serotyping by the Public Health Laboratory Service (PHLS) Division of Enteric Pathogens has increased by 60% (Table 1). This is predominantly due to strains of Salmonella typhimurium and S. enteritidis. Smaller but significant increases have occurred in the numbers of S. virchow and S. Stanley. With the exception of the latter serotype, which seems to come from a bovine reservoir, the indications aro that poultry is the main source of the increase in infections.

Human cases of Q fever appear to be common in Northern Ireland compared to the rest of the British Isles. The purpose of this study was to describe the seroepidemiology of Coxiella burnetii infection in cattle in Northern Ireland in terms of seroprevalence and determinants of infection. A total of 5182 animals (from a stratified systematic random sample of 273 herds) were tested with a commercial C. burnetii phase 2 IgG ELISA. A total of 6·2% of animals and 48·4% of herds tested positively. Results from a multilevel logistic regression model indicated that the odds of cattle being infected with Q fever increased with age, Friesian breed, being from large herds and from dairy herds. Large dairy herd animal prevalence was 12·5% compared to 2·1% for small beef herds. Preliminary seroprevalence in sheep (12·3%), goats (9·3%), pigs (0%) rats (9·7%) and mice (3·2%) using indirect immunofluorescence is reported.

A cross-sectional study based on a questionnaire survey was conducted to determine the distribution of lumpy skin disease (LSD) and associated risk factors in three main agro-climatic zones of Ethiopia. A total of 330 questionnaire surveys were collected from 44 peasant associations (PA) distributed in 15 districts. Across agro-climate zones, herd-level LSD prevalence in the midland agro-climate was significantly higher 55·2% [95% confidence interval (CI) 47·5–62·6] than in highland and lowland agro-climate zones. Overall observed LSD prevalence at animal-level was 8·1% (95% CI 7·3–8·9) and observed mortality was 2·12% (95% CI 1·73–2·6). The odds ratio (OR) of LSD occurrence in midland vs. highland and lowland vs. highland zones was 3·86 (95% CI 2·61–5·11) and 4·85 (95% CI 2·59–7·1), respectively. Significantly high risk of LSD occurrence was associated with communal grazing and watering management (OR 4·1, 95% CI 2·02–6·18) and introduction of new cattle (OR 8·5, 95% CI 6·0–11·0). Our findings describe the distribution of LSD in different agro-climates in Ethiopia along with associated risk factors, and can help shed light on the epidemiology of LSD in other African countries suffering from the disease.

The mean time-survivor curves of bacteria immersed in two phenolic disinfectants show the same variation of type as the individual curves, that is, (a) an exponential rate, (b) a lag phase followed by an exponential rate. The significance of all these curves and of others is discussed in the next part of the paper.

The number of deaths attributable to influenza is believed to be considerably higher than the number certified by vital statistics registration as due to influenza. Weekly mortality data for Canada from the 1989/1990 to the 1998/1999 influenza seasons were analysed by cause of death, age group, and place of death to estimate the impact of influenza on mortality. A Poisson regression model was found to accurately predict all-cause, as well as cause-specific mortality, as a function of influenza-certified deaths, after controlling for seasonality, and trend. Influenza-attributable deaths were calculated as predicted less baseline-predicted deaths. In summary, throughout the 1990s there were on average just under 4000 deaths attributable to influenza annually (for an influenza-attributable mortality rate of 13/100 000 persons), varying from no detectable excess mortality for the 1990/1991 influenza season, to 6000–8000 influenza-attributable deaths for the more severe influenza seasons of 1997/1998 and 1998/1999. On average, 8% (95% CI 7–10) of influenza-attributable deaths were certified as influenza, although this percentage varied from 4% to 12% from year to year. Only 15% of the influenza-attributable deaths were certified as pneumonia, and for all respiratory causes, 40%. Deaths were distributed over most causes. The weekly pattern of influenza-certified deaths was a good predictor of excess all-cause mortality.

The consumption of bi-valve mollusean shellfish has been associated with outbreaks of viral gastroenteritis and hepatitis A. Investigations were undertaken to determine the heat inactivation conditions necessary to render shellfish such as cockles safe for the consumer. Conditions for the laboratory maintenance of live cockles are described. In preliminary experiments either poliovirus (106 TCID50/ml seawater) or hepatitis A virus (HAV) (approx. 104 RFU/ml seawater) was introduced into the shellfish tank. Following 48 h filter feeding, virus was recovered from cockles using an adsorption-elution extraction procedure. Titres of virus recovered ranged from 104 to 105 TCID50/ml of shellfish extract for poliovirus and from 103 to 105 RFU/ml of shellfish extract for HAV. Active ingestion of the virus from the seawater was demonstrated by recovering virus from within cockle guts. To quantify recovered HAV, end-point dilutions and an adaptation of a radioimmunofocus assay (RIFA) were compared. The tests were of similar sensitivity but the RIFA has the advantage of being relatively rapid, shortening the time taken to complete an experiment by as much as 4 weeks.

We examined clinical and epidemiological features of 575 laboratory-confirmed cases of vibrio gastroenteritis in Alabama, Florida, Louisiana, and Texas from 1988 to 1997 (the US Gulf of Mexico Regional Vibrio Surveillance System). Illnesses occurred year round, with peaks in spring and autumn. Illnesses lasted a median of 7 days and included fever in half of patients and bloody stools in 25% of patients with relevant information. Seventy-two percent of patients reported no underlying illnesses. In the week before onset, 236 (53%) of 445 patients for whom data were available ate raw oysters, generally at a restaurant or bar. Educational efforts should address the risk of vibrio gastroenteritis for raw oyster consumers, including healthy individuals. Further studies should examine environmental conditions affecting vibrio counts on seafood and processing technologies to enhance the safety of raw oysters.

Salmonella enteritidis PT4 was recovered from fingers following the breaking of intact shell eggs artificially contaminated in the contents with the bacterium. Kitchen utensils used to mix egg dishes were salmonella-positive, sometimes after washing. Following the preparation of batter or the mixing of eggs, S. enteritidis was recovered from work surfaces over 40 cm from the mixing bowl. The bacterium survived well in thin, dry films of either batter or egg and, from an initial level of one cell per cm2, could be recovered from formica work surfaces 24 h after contamination.

ELISA techniques developed for the veterinary diagnosis of Rabbit Haemorrhagic Disease (RHD) in domestic rabbits were used for studying the epidemiology of RHD in Australian wild rabbits. The combination of ELISA techniques that distinguished IgA, IgG and IgM antibody responses and a longitudinal data set, mainly based on capture-mark-recapture of rabbits, provided a reliable basis for interpreting serology and set the criteria used to classify rabbits' immunological status. Importantly, young with maternal antibodies, immune rabbits and rabbits apparently re-exposed to RHD were readily separated. Three outbreaks of RHD occurred in 1996–7. The timing of RHD outbreaks was mainly driven by recruitment of young rabbits that generally contracted RHD after they lost their maternally derived immunity. Young that lost maternal antibodies in summer were not immediately infected, apparently because transmission of RHDV slows at that time, but contracted RHD in the autumn when conditions were again suitable for disease spread.

VP1 gene sequences of SAT-2 type foot-and-mouth disease (FMD) viruses recovered from impala and African buffalo in the Kruger National Park (KNP) were used to determine intra- and interspecies relationships of viruses circulating in these wildlife populations. On this basis five distinct lineages of SAT-2 virus were identified in routine sampling of oesophageo-pharyngeal epithelium from buffalo between 1988 and 1996. Different lineages were associated with discrete geographic sampling localities. Over the period 1985–95, four unrelated epizootics occurred in impala in defined localities within the KNP. Evidence for natural transmission of FMD between buffalo and impala is presented for the most recent 1995 outbreak, with data linking the 1985 and 1988/9 impala epizootics to viruses associated with specific buffalo herds.

Mycobacterium ulcerans, the organism which causes Buruli or Bairnsdale ulcer, has never been isolated in culture from an environmental sample. Most foci of infection are in tropical regions. The authors describe the first 29 cases of M. ulcerans infection from a new focus on an island in temperate southern Australia, 1992–5. Cases were mostly elderly, had predominantly distal limb lesions and were clustered in a small region in the eastern half of the main town on the island. The authors suspected that an irrigation system which lay in the midst of the cluster was a source of infection. Limitation of irrigation was associated with a dramatic reduction in the number of new cases. These findings support the hypothesis that M. ulcerans has an aquatic reservoir and that persons may be infected directly or indirectly by mycobacteria disseminated locally by spray irrigation.

Infection of wild animals by bovine tuberculosis (bTB) is raising concern worldwide. This article reviews the current epidemiological situation, risk of emergence and control options at the wildlife–livestock–human interface in sub-Saharan Africa. In livestock, bTB has been confirmed in the majority of countries from all parts of the continent. Wildlife infection is confirmed in seven countries from southern and eastern Africa, apparently spreading in the southern Africa region. Mycobacterium bovis has been isolated from 17 wild mammal species, although only four are suspected to play a role as maintenance host. Zoonotic risks are a concern, but no direct spillover from wildlife to humans has been documented, and no case of bTB spillback from wildlife to livestock has been confirmed. In this paper we assess the main risk factors of bTB spillover at the wildlife–livestock–human interface and suggest several research themes which could improve the control of the disease in the African context.

Rabbits immunized with whole streptococci of group B, type II, produce two immunologically distinct type-specific antibodies which are essentially equal by weight in protecting mice against infection with homologous type strains.

The capsular antigen with which these antibodies react is a polysaccharide containing galactose, glucose, glucosamine, and a labile component which has not been chemically identified. Extraction of the bacteria with TCA yields this ‘complete’ antigen, whereas extraction with HCl yields a partial antigen without the labile component. This degraded antigen can also be derived from the TCA antigen by treating the latter with hot HCl, and is indistinguishable from that extracted directly from the bacteria with HCl.

One of the antibodies produced, the TCA antibody, is directed against the labile component of the polysaccharide. The other, the HCl antibody, is directed against a β-d-galactoside determinant; and the precipitin reaction with this antibody is not masked in the ‘complete’ TCA antigen by the presence of the labile component.

The group-specific polysaccharide, which is located in the cell-wall, is also extracted with either TCA or HCl but can be eliminated from the preparations by fractional precipitation with ethanol. Although it is known that the type-specific polysaccharide is located in the streptococcal capsule, it is not at present clear in what form this substance occurs in the living streptococcal cell. It may be present partially as the degraded HCl form, or possibly wholly as the intact TCA form. Further immunological and chemical studies of these type-specific polysaccharides are in progress, and will be presented in another communication.

A prevalence survey of nasal methicillin-resistant Staphylococcus aureus (MRSA) carriage was undertaken on a random sample of adults (aged over 16) resident in the community in Birmingham, UK during 1998. Microbiological samples were taken from the anterior nares at the subjects' general practice or in their home. Information about risk factors for the acquisition of MRSA was obtained via a self-completed questionnaire. A 58% response rate (280/483) was achieved. The prevalence of nasal MRSA colonization was 1.5% [4/274, 95% confidence interval (CI) 0.03–2.9%]. Twenty-three per cent (63/274) of subjects were nasal carriers of S. aureus. Six per cent (4/63) of S. aureus isolates were MRSA and 2 of the 4 MRSA carriers reported previous contact with health facilities. The prevalence of MRSA colonization in the general adult population in Birmingham appears to be low.

Hepatitis C virus (HCV) among injecting drug users (IDUs) is one of the European Union's (EU) major public health problems. This review examines the current state of knowledge regarding HCV among IDUs in EU countries. Studies published between January 1990 and December 2000, were identified through a computerized search (MEDLINE and EMBASE). Ninety-eight studies have reported prevalence for HCV among groups of IDUs in all EU countries except Luxembourg. The prevalence of anti-HCV ranged from 30 to 98%. Incidence rates ranged from 6·2 to 39·3 per 100 person years. This review provides a comprehensive examination of HCV infection among IDUs in the countries of the EU, and quite clearly demonstrates that the quality and epidemiological relevance of the studies published varies widely. Thus, the reported data may not reflect accurately the current or recent past prevalence of HCV among IDUs in the EU. A strategic approach to the surveillance of HCV among IDUs in the EU, utilizing robust and consistent methods, is required urgently.

After oral contamination of conventional mice with high doses of Escherichia coli, Klebsiella pneumoniae or Pseudomonas aeruginosa the contaminant was recovered in abnormally high concentrations from the duodenum and caecum during the first few days. In this initial colonization phase, evidence of spread was obtained by culturing the cervical and mesenteric lymph nodes and spleen. Longer after contamination the intestinal concentration decreased to normal and spread stopped. In orally antibiotic-treated mice, the situation seen during the initial colonization phase in conventional mice occurred after a much lower oral contamination dose and persisted during the entire observation period of 2 weeks.

Foodborne outbreaks of Salmonella enterica serovar Enteritidis phage type 4 (PT4) infection (n=497), reported to the Health Protection Agency Communicable Disease Surveillance Centre between 1992 and 2002, were compared with other pathogens (n=1148) to determine factors (season, setting, food vehicles, food safety faults) associated with this pathogen. Logistic regression was applied to control for potential confounding. Foodborne general outbreaks of S. Enteritidis PT4 infection were more likely to occur in the spring and summer, and were more often linked to schools, private residences and residential institutions. Eggs, egg products and the use of raw shell egg were strongly associated with this pathogen. Most outbreaks were linked to cross-contamination and inadequate heat treatment. This paper describes the decline in the S. Enteritidis PT4 epidemic, providing evidence that control measures introduced, e.g. improved biosecurity and vaccination, have worked. Continued surveillance of human and veterinary salmonellosis is essential to detect future problems.

To estimate the frequency of infectious gastroenteritis across Australia, and to identify risk factors, we conducted a national telephone survey of 6087 randomly selected respondents in 2001–2002. The case definition was three or more loose stools and/or two or more vomits in a 24-hour period in the last 4 weeks, with adjustment to exclude non-infectious causes and symptoms secondary to a respiratory infection. Frequency data were weighted to the Australian population. Multivariate logistic regression was used to assess potential risk factors including season, region, demographic and socioeconomic status. Among contacted individuals, 67% responded. The case definition applied to 7% of respondents (450/6087) which extrapolates to 17·2 million (95% CI 14·5–19·9 million) cases of gastroenteritis in Australia in one year, or 0·92 (95% CI 0·77–1·06) cases/person per year. In the multivariate model, the odds of having gastroenteritis were increased in summer and in the warmest state, in young children, females, those with higher socioeconomic status and those without health insurance.

Waterborne illness related to the consumption of contaminated or inadequately treated water is a global public health concern. Although the magnitude of drinking water-related illnesses in developed countries is lower than that observed in developing regions of the world, drinking water is still responsible for a proportion of all cases of acute gastrointestinal illness (AGI) in Canada. The estimated burden of endemic AGI in Canada is 20·5 million cases annually – this estimate accounts for under-reporting and under-diagnosis. About 4 million of these cases are domestically acquired and foodborne, yet the proportion of waterborne cases is unknown. There is evidence that individuals served by private systems and small community systems may be more at risk of waterborne illness than those served by municipal drinking water systems in Canada. However, little is known regarding the contribution of these systems to the overall drinking water-related AGI burden in Canada. Private water supplies serve an estimated 12% of the Canadian population, or ~4·1 million people. An estimated 1·4 million (4·1%) people in Canada are served by small groundwater (2·6%) and surface water (1·5%) supplies. The objective of this research is to estimate the number of AGI cases attributable to water consumption from these supplies in Canada using a quantitative microbial risk assessment (QMRA) approach. This provides a framework for others to develop burden of waterborne illness estimates for small water supplies. A multi-pathogen QMRA of Giardia, Cryptosporidium, Campylobacter, E. coli O157 and norovirus, chosen as index waterborne pathogens, for various source water and treatment combinations was performed. It is estimated that 103 230 AGI cases per year are due to the presence of these five pathogens in drinking water from private and small community water systems in Canada. In addition to providing a mechanism to assess the potential burden of AGI attributed to small systems and private well water in Canada, this research supports the use of QMRA as an effective source attribution tool when there is a lack of randomized controlled trial data to evaluate the public health risk of an exposure source. QMRA is also a powerful tool for identifying existing knowledge gaps on the national scale to inform future surveillance and research efforts.

The epizootic range of Rift Valley fever in Kenya is defined from the results of virus isolations during epizootics, and from an extensive serological survey of cattle which were exposed during an epizootic. A study of the sera from a wide range of wild bovidae sampled immediately after the epizootic, showed that they did not act as reservoir or amplifying hosts for RVF.

Virus isolation attempts from a variety of rodents proved negative. Rift Valley fever did not persist between epizootics by producing symptomless abortions in cattle in areas within its epizootic range. A sentinel herd sampled annually after an epizootic in 1968 revealed not one single seroconversion from 1969 to 1974. Certain forest and forest edge situations were postulated as enzootic for Rift Valley fever, and a small percentage of seroconversions were detected in cattle in these areas, born four years after the last epizootic. This has been the only evidence for the persistence of the virus in Kenya since 1968, and may be a part of the interepizootic maintenance cycle for Rift Valley fever in Kenya, which otherwise remains unknown.