Unidentified open-air factors (OAFs) found to be adverse to the survival of microorganisms suspended on microthreads were investigated for their effect on realistic aerosols of Francisella tularensis in an open-air environment. This organism was chosen because it is probably the most infectious organism known to be capable of infecting both animals and man via the respiratory route, hence its potential use as a bioterrorist agent. A direct correlation was found between an open-air adverse effect on viability and virulence of airborne particles of <3 μm via the respiratory route in guinea pigs. One viable organism was sufficient to initiate an infection that resulted in a fatal tularaemia infection. The lethal effect of OAFs on F. tularensis was found to vary from day to day and was related to the source of the air in the UK. The adverse effect on viability was associated with an inverse effect according to the size of the airborne particle.

Scrapie is a fatal neurological disease of sheep which is endemic in the United Kingdom. It is one of the family of transmissible spongiform encephalopathies (TSEs) that includes BSE. In this paper, we developed a micro-simulation model for scrapie in the UK sheep population, incorporating the genetic and structural diversity of the population and infectious contact between flocks through trading. The simulation was fitted to epidemiological data from a range of sources. We found a detection/reporting probability of 16% (95% CI 12–17) for animals dying of scrapie. Prevalence of infected animals in the population was about 0·15%. Infected individuals were found in 9% of flocks overall, rising to 60% in Shetland and 75% in Swaledale flocks. Mean values of R0 for flocks varied with breed from 2·43 (Shetland) to 0·21 (Suffolk). We also examined the possible long-term persistence of scrapie in the UK flock in the absence of any intervention.

Scrapie is a fatal transmissible spongiform encephalopathy (TSE) of sheep, endemic in the UK for centuries. Interest in the disease has been heightened over the last decade by the possibility of the related BSE being transmissible to and between sheep and a range of control interventions has been proposed and implemented. In this paper, we examined the effect of these policies and their components on observed case rate, susceptible allele frequency and R0 within the framework of a large simulation model of the British sheep population and its breeding and trading structure. We compared interventions with the natural fade-out of scrapie in the population through loss of susceptible genotypes in the absence of control. We compare the results of interventions with the natural course of the scrapie epidemic. Our model suggested that scrapie will persist in the national flock for 300–400 years with the impact on gene frequencies confined largely to high case-rate breeds, such as Shetland and Swaledale. We found the National Scrapie Plan (NSP) to be the most effective in terms of the removal of both susceptible genotypes and scrapie from the population. Complete eradication of scrapie can be achieved within 32 years (95% CI 23–43 years). The Compulsory Scrapie Flock Scheme (CSFS) is as effective as the NSP in reducing the observed case rate but has a limited impact on the frequencies of susceptible genotypes in the population overall. In combination with the NSP, eradication of scrapie is achieved >10 years faster. Of the components of the CSFS, the breeding and culling aspects are each almost as effective as the full policy, with trading restrictions contributing little. We have speculated on the impact of control measures on the possibility BSE infection within the national flock by examining their effect on flock R0 for BSE across different breeds.

Extensive surveillance for classical scrapie has been carried out in Great Britain since 1993, the results of which can be used for monitoring the effect of control measures introduced since 2001. A back-calculation approach was used to estimate the prevalence of sheep infected with classical scrapie, which integrates data on reported clinical cases (1993–2007) and the results of fallen stock and abattoir surveys (2002–2007). The prevalence of classical scrapie in GB was fairly constant until 2003, although the estimates depended on assumptions made about the performance of diagnostic tests used in the surveys. If infected animals could be detected in the final quarter of the incubation period, the estimated prevalence was 0·6–0·7%, while if they could be detected in the final half of the incubation period, it was 0·3–0·4%. Between 2003 and 2007 the prevalence declined by around 40%, and the magnitude of the reduction was independent of assumptions made about the diagnostic tests.

Some European countries decided to include human papillomavirus (HPV) vaccines in national immunization schedules. In order to help decision makers choose the best vaccination policy for females, a decisional model has been developed. The study was performed from the National Health Service perspective. Several hypotheses of multi-cohort vaccination policies were compared. ‘Potentially avoidable infections’ were chosen as the outcome. The model envisioned a short-term scenario (2008–2011). The best policy was that of vaccinating 12-year-olds and, a year later, those aged 14–16 years; the most expensive strategy was that of vaccinating 12-year-old females and, after 1 year, vaccinating those aged 15, 18 and 25 years. The sensitivity analysis showed that coverage rate has a great effect on the cost of avoidable infections. The study offers stake-holders an important datum-point for the choice of the best HPV policy vaccination in the short term. Indeed, it could generate interesting savings for the National Health Service and a rapid HPV immunization of young girls.

We present the frequency and the nature of contact incidents of the Serotine bat, Eptesicus serotinus, with humans and with companion animals (specifically cats and dogs), in The Netherlands between 2000 and 2005. Out of 17 bats in bite contact with humans, five tested positive for European bat lyssavirus (EBLV) type 1a. Cats had the most numerous contacts with bats (49 times) but a relatively low number of these bats were EBLV positive (six times). We estimated that the average incidence of human bat rabies infection might be between once per year and once per 700 years, depending mainly on the number of infectious viral particles in bat saliva. The risk of bat rabies is higher between April and October, and in the northern half of the country. This is the first study in Europe describing the risk of human bat rabies after bat contact incidents.

Identifying county-level sociodemographic and economic factors associated with the incidence of enteric disease may provide new insights concerning the dynamics of community transmission of these diseases as well as opportunities for prevention. We used data from the National Notifiable Diseases Surveillance System, the U.S. Census Bureau, and the Health Resources and Services Administration to conduct an ecological analysis of 26 sociodemographic and economic factors associated with the incidence of salmonellosis, shigellosis, and E. coli O157:H7 infections in US counties for the period 1993 to 2002. Our study indicates that race, ethnicity, place of residence, age, educational attainment, and poverty may affect the risk of acquiring one of these enteric bacterial diseases. The lack of specificity of information regarding salmonellae and shigellae serotypes may have led to less specific associations between community-level determinants and reported incidence of those diseases. Future ecological analyses should use serotype-specific data on incidence, which may be available from laboratory-based surveillance systems.

The aim of this study was to assess the effects of reductions in the number of isolates tested by phage-typing on the recognition of outbreaks of salmonellosis. Five outbreaks (categorized as ‘small’, ‘medium’ or ‘large’) which occurred in England in 2005 were used as examples. The outbreaks were caused by serotypes which were subdivided by phage-typing. Results indicated that reducing the number of isolates phage-typed would have an impact on the surveillance system, with one outbreak likely to have been missed altogether. However, this does not have a great effect on the ‘time-to-detection’ for the other outbreaks. Assuming no testing for phage-typing was undertaken it is likely that two out of five outbreaks would not have been detected. Assessing the value of phage-type information is important not only in deciding on the efficiency of the current surveillance system but also in providing a basis upon which to assess more detailed typing methodologies such as an antibiogram of molecular profile.

A public plan for eradicating Salmonella in Danish table-egg production was implemented in 1996. During 2002, the poultry industry took over the responsibility of the programme. The proportion of infected layer flocks was reduced from 13·4% in 1998 to 0·4% in 2006. The public-health impact of the plan has been quite marked. In 1997, 55–65% of the 5015 cases of human salmonellosis were estimated to be associated with eggs. In 2006, these figures were reduced to 1658 and 5–7%, respectively. Based on an assessment of the number of human cases attributable to table eggs, we used probabilistic modelling to estimate the avoided societal costs (health care and lost labour), and compared these with the public costs of control. The probable avoided societal costs during 1998–2002 were estimated to be 23·3 million euros (95% CI 16·3–34·9), and the results showed a continuous decreasing cost–benefit ratio reaching well below 1 in 2002. Further reductions in the primary production based on effective surveillance and control are required to ensure continued success.

We investigated factors associated with persistence of different Salmonella serovars in buildings housing laying hens in Great Britain using survival analysis. A total of 264 incidents of Salmonella detection occurring between July 1998 and August 2007 in 152 houses were recorded. For incidents involving Salmonella Enteritidis (SE), both the rodent score of the house and the type of house were positively associated with persistence. For non-SE serovars, only the type of house was associated with persistence. Persistence of SE in the houses was longest (>15 months) in step-cage and cage-scraper houses when high levels of rodents were present, and lowest in non-cage and cage-belt houses. We estimated that 42% (95% CI 23·3–63·1) of SE incidents may be cleared during the lay period, and this was related to elimination of rodents from the houses. From January 2009, EU legislation will ban the sale of fresh eggs from SE-positive and S. Typhimurium-positive flocks over their remaining lifespan. If infection is eliminated from such flocks, they would cease to represent a public health risk.

Using data from a cohort study conducted by the Veterinary Laboratories Agency (VLA), evidence of spatial clustering at distances up to 30 km was found for S. Agama and S. Dublin (P values of 0·001) and borderline evidence was found for spatial clustering of S. Typhimurium (P=0·077). The evolution of infection status of study farms over time was modelled using a Markov Chain model with transition probabilities describing changes in status at each of four visits, allowing for the effect of sampling visit. The degree of geographical clustering of infection, having allowed for temporal effects, was assessed by comparing the residual deviance from a model including a measure of recent neighbourhood infection levels with one excluding this variable. The number of cases arising within a defined distance and time period of an index case was higher than expected. This provides evidence for spatial and spatio-temporal clustering, which suggests either a contagious process (e.g. through direct or indirect farm-to-farm transmission) or geographically localized environmental and/or farm factors which increase the risk of infection. The results emphasize the different epidemiology of the three Salmonella serovars investigated.

Salmonella infections in Antarctic wildlife were first reported in 1970 and in a search for evidence linking isolations with exposure to human activities, a comparison was made of serovars reported from marine fauna in the Antarctic region from 1982–2004 with those from marine mammals in the Northern hemisphere. This revealed that 10 (83%) Salmonella enterica serovars isolated from Antarctic penguins and seals were classifiable in high-frequency (HF) quotients for serovars prevalent in humans and domesticated animals. In Australia, 16 (90%) HF serovars were isolated from marine birds and mammals compared with 12 (86%) HF serovars reported from marine mammals in the Northern hemisphere. In Western Australia, HF serovars from marine species were also recorded in humans, livestock, mussels, effluents and island populations of wildlife in urban coastal areas. Low-frequency S. enterica serovars were rarely detected in humans and not detected in seagulls or marine species. The isolation of S. Enteritidis phage type 4 (PT4), PT8 and PT23 strains from Adélie penguins and a diversity of HF serovars reported from marine fauna in the Antarctic region and coastal areas of Australia, signal the possibility of transient serovars and endemic Salmonella strains recycling back to humans from southern latitudes in marine foodstuffs and feed ingredients.

Fourteen strains of S. Typhi (n=13) and S. Paratyphi A (n=1) resistant to ciprofloxacin were compared with 30 ciprofloxacin decreased-susceptibility strains on the basis of qnr plasmid analysis, and nucleotide substitutions at gyrA, gyrB, parC and parE. In ciprofloxacin-resistant strains, five S. Typhi and a single S. Paratyphi A showed triple mutations in gyrA (Ser83→Phe, Asp87→Asn, Glu133→Gly) and a novel mutation outside the quinolone resistance determining region (QRDR) (Met52→Leu). Novel mutations were also discovered in an isolate (minimum inhibitory concentration 8 μg/ml) in gyrA gene Asp76→Asn and outside the QRDR Leu44→Ile. Out of 30 isolates with reduced susceptibility, single mutation was found in 12 strains only. Genes encoding qnr plasmid (qnr A, qnr B, AAC1-F) were not detected in ciprofloxacin-resistant or decreased-susceptibility strains. Antimicrobial surveillance coupled with molecular analysis of fluoroquinolone resistance is warranted for reconfirming novel and established molecular patterns of resistance, which is quintessential for reappraisal of enteric fever therapeutics.

We surveyed antimicrobial susceptibility in faecal Escherichia coli in primary schoolchildren in rural Tamil Nadu, India. Resistance profiles of E. coli samples from local water sources were also obtained. We investigated sociodemographic characteristics as risk factors for resistance and local paediatric prescription patterns. In 119 stool samples, carriage of resistance to ⩾1 antibiotic was 63% and multiple drug resistance was 32%. Resistance outcomes were associated with school of attendance, having a sibling attend the same school, younger age, and less crowded households. Eight of nine water samples were resistant to ⩾1 antibiotic. Recent history of medication use was not associated with resistance carriage. Resistance patterns may have been influenced by local paediatric prescription patterns and veterinary antibiotic use. Frequent, low-cost surveillance of commensal resistance can guide development of locally appropriate treatment guidelines. School-based hygiene programmes should be considered as means of limiting the spread of antibiotic resistance.

On 24–25 October 2005 a cluster of five haemolytic uraemic syndrome (HUS) cases was reported in southwest France. An investigation was undertaken to identify the outbreak source and implement control measures. Cases were defined as individuals with HUS or diarrhoea with isolation of Escherichia coli O157:H7 in stools or a positive antibody response to E. coli O157 lipopolysaccharide, resident in southwest France with symptom onset after 19 September 2005. Sixty-nine identified patients had symptom onset between 5 October and 3 November 2005, including 17 cases of HUS. One brand of frozen beef burgers produced on 22 August 2005 was consumed by all patients in the week before symptom onset. E. coli O157:H7 strains from patients, patients' burgers and the manufacturing plant were genetically related. This is the largest community-wide outbreak of E. coli O157:H7 in France to date and the first associated with consumption of contaminated frozen beef burgers.

Young children account for a large proportion of reported Yersinia enterocolitica infections in Sweden with a high incidence compared with other gastrointestinal infections, such as salmonellosis and campylobacteriosis. A case-control study was conducted to investigate selected risk factors for domestic sporadic yersiniosis in children aged 0–6 years in Sweden. In total, 117 cases and 339 controls were included in the study. To minimize exclusion of observations due to missing data a multiple non-parametric imputation technique was used. The following risk factors were identified in the multivariate analysis: eating food prepared from raw pork products (OR 3·0, 95% CI 1·8–5·1) or treated sausage (OR 1·9, 95% CI 1·1–3·3), use of a baby's dummy (OR 1·9, 95% CI 1·1–3·2) and contact with domestic animals (OR 2·0, 95% CI 1·2–3·4). We believe that the importance of Y. enterocolitica infection in children has been neglected and that results from this study can be used to develop preventive recommendations.

We investigated two sequential outbreaks of severe diarrhoea in two neighbouring villages of Orissa, in 2005. We conducted descriptive and matched case-control studies. The attack rates were 5·6% (n=62) and 5·2% (n=51), respectively, in the first and second villages. One death was reported in the second village (case fatality 2%). We identified that consumption of milk products prepared in the household of the index case [matched odds ratio (mOR) 5·7, 95% confidence interval (CI) 1·7–30] in the first village, and drinking well water in the second village were associated with the illness (mOR 4·7, 95% CI 1·6–19). We isolated Vibrio cholerae El Tor O1 Ogawa from stool samples from both the villages. Mishandling of milk products led to a cholera outbreak in the first village, which led to sewerage contamination of a well and another outbreak in the second village. Environmental contamination should be expected and prevented during cholera outbreaks.