People living in endemic areas acquire Lyme disease from the bite of an infected tick. This infection, when diagnosed and treated early in its course, usually responds well to antibiotic therapy. A minority of patients develops more serious disease, particularly after a delay in diagnosis or therapy, and sometimes chronic neurological, cardiac, or rheumatological manifestations. In 1998, the FDA approved a new recombinant Lyme vaccine, LYMErix™, which reduced new infections in vaccinated adults by nearly 80%. Just 3 years later, the manufacturer voluntarily withdrew its product from the market amidst media coverage, fears of vaccine side-effects, and declining sales. This paper reviews these events in detail and focuses on the public communication of risks and benefits of the Lyme vaccine and important lessons learned.

We describe parental attitude towards mass antimicrobial prophylaxis and adolescent booster vaccination to prevent pertussis. A survey was distributed to parents at a large suburban high school where an outbreak of pertussis was occurring. A total of 314 surveys were received among 450 distributed. If antimicrobial prophylaxis was recommended for all students and faculty as a method of controlling a pertussis outbreak in their child's school (i.e. mass antimicrobial prophylaxis), 40% of parents would have their child take the medication and 49% might have their child take the antibiotic but would first consult their child's physician. Having [ges ]2 children attend the high school (OR 2·2, 95% CI 1·10–4·59) and generally favouring immunizations (OR 1·7, 95% CI 0·99–2·87) were predictors of likely compliance with mass antimicrobial prophylaxis. These findings underscore the importance of communicating the rationale of public health intervention efforts to physicians in order to help ensure their success.

Official statistics routinely underestimate mortality from specific microorganisms and deaths are assigned to non-specific syndromes. Here we estimate mortality attributed to specific pathogens by modelling non-specific infant deaths from laboratory reports and codes on death certificates for these pathogens, 1993–2000 in England and Wales using a generalized linear model. In total, 22·4–59·8% of non-specific deaths in infants (25–66 deaths a year) are attributable to specific pathogens. Yearly deaths from Bordetella pertussis in neonates are 6·8 [95% confidence interval (CI) 1·5–11·9]. In post-neonates 9·4 (95% CI 2·3–16·6) deaths a year are attributable to Neisseria meningitidis, 7·3 (95% CI 2·4–12·3) to Streptococcus pneumoniae, from 2·8 (95% CI 0·8–4·9) to 15·1 (95% CI 9·4–20·9) to respiratory syncytial virus (RSV) and 3 (95% CI 0·3–5·9) to parainfluenza type 2. Our results suggest there is substantial hidden mortality for a number of pathogens in infants. A considerable proportion of deaths classified to infectious syndromes are non-infectious, suggesting low specificity of death certification. Laboratory reports were the more reliable source, reinforcing the asset of strong surveillance systems.

A simulation study using Greenwood's chain-binomial model was carried out to elucidate the spread and control of Mycobacterium tuberculosis among the household contacts of infectious pulmonary tuberculosis (TB) patients. Based on the observed data, the maximum-likelihood estimates (±S.E.) of chain-binomial probabilities of intra-household M. tuberculosis transmission from an index case in 3-person and 4-person households were 0·313±0·008 and 0·325±0·009 respectively. The χ2 goodness-of-fit test of observed and simulated mean expected frequencies of cases revealed good fit for 3-person (P=0·979) and 4-person (P=0·546) households. With the assumption of varying risk of M. tuberculosis transmission across the households under β-distribution, goodness-of-fit tests of observed and mean simulated expected frequencies revealed the inadequacy of Greenwood's chain-binomial model both for 3-person (P=0·0185) and 4-person (P<0·001) households. Simulated M. tuberculosis control strategy comprising efficient diagnosis, segregation and prompt antibiotic therapy of index pulmonary TB patients showed a substantial reduction of new cases among the household contacts in both household sizes. In conclusion, segregation coupled with prompt antibiotic therapy of the index case, chemoprophylaxis of M. tuberculosis-exposed household contacts, and the assessment of household environmental risks to devise and implement an educational programme may help reduce the TB burden in this and similar settings.

A case-control study was performed in South Australia to determine if L. longbeachae infection was associated with recent handling of commercial potting mix and to examine possible modes of transmission. Twenty-five laboratory-confirmed cases and 75 matched controls were enrolled between April 1997 and March 1999. Information on underlying illness, smoking, gardening exposures and behaviours was obtained by telephone interviews. Recent use of potting mix was associated with illness (OR 4·74, 95% CI 1·65–13·55, P=0·004) in bivariate analysis only. Better predictors of illness in multivariate analysis included poor hand-washing practices after gardening, long-term smoking and being near dripping hanging flower pots. Awareness of a possible health risk with potting mix protected against illness. Results are consistent with inhalation and ingestion as possible modes of transmission. Exposure to aerosolized organisms and poor gardening hygiene may be important predisposing factors to L. longbeachae infection.

A resurgence of Mycobacterium bovis infections in cattle in the United Kingdom since the 1980s has raised concern about risks to human health. Enhanced surveillance data for England, Wales and Northern Ireland between 1993 and 2003 of culture-positive human M. bovis cases identified 315 M. bovis infections; the mean annual number of cases was 28 (range 12–41). The most frequently reported exposures were consumption of unpasteurized dairy products 41/83 (49%) and exposure to cattle 45/123 (37%). Of all cases, 249 (83%) were born before 1960. Of 50 cases born after 1960, only 14 were born in the United Kingdom. Over the same time period the annual number of new herd infections increased from 332 to 1749 as derived from the UK State Veterinary Service database. In conclusion, despite a more than fivefold increase in cattle herd infections during the 1990s, there was no increase in reported human cases.

The paper proposes a model explaining the spatial variation in incidence of nephropathia epidemica in Europe. We take into account the rodent dynamic features and the replicative dynamics of the virus in animals, high in the acute phase of newly infected animals and low in the subsequent chronic phase. The model revealed that only vole populations with multi-annual fluctuations allow for simultaneously high numbers of infected rodents and high proportions of those rodents in the acute excretion phase during the culminating phase of population build-up. This leads to a brief peak in exceptionally high concentrations of virus in the environment, and thereby, to human exposure. Such a mechanism suggests that a slight ecological disturbance in animal–parasite systems could result in the emergence of human diseases. Thus, the potential risk for public health due to several zoonotic diseases may be greater than previously believed, based solely on the distribution of human cases.

West Nile virus (WNV) outbreak in North Dakota in 2002 included over 569 horse cases, clustered mainly in the eastern and northeastern parts of the state. The pattern of occurrence observed suggested existence of specific environmental and ecological factors that increased the risk for infection and illness in those locations. We developed a predictive model with factors that explained the pattern of WNV occurrence observed. Results indicated that surface elevation, temperature, precipitation, reported WNV-positive birds, reported WNV-positive humans, and reported WNV-positive mosquitoes were important predictors of occurrence in horses. However, case distance from water bodies was not significant in the model. Future predictive models of WNV occurrence in horses should take into account these factors in order to improve accuracy and reliability. Research into other potential determinants such as horse management factors are required to determine more differential risk factors associated with WNV occurrence in horses.

Diagnosis and treatment of endemic infectious disease is crucial for productivity of cattle in rural sub-Saharan Africa, but shortages of trained veterinary professionals necessitate support for less well-trained cadres of animal health worker. A Delphi survey of veterinary experts provided quantitative information on key clinical signs associated with eight endemic bovine diseases, then heuristics and dendrogram analysis identified a reduced sign set to be incorporated in a diagnostic decision support tool implemented as a simple colour-banded card. One hundred and seventy disease-sign questionnaire returns were obtained from 32 veterinary research scientists and 14 veterinary practitioners. Preliminary validation of the decision support tool for 16 prototypical cases resulted in ‘correct’ diagnosis over 90% of the time. The card potentially serves as a training aid and aide-mémoire, and could improve the diagnostic competence of animal healthcare providers.

One strain of Salmonella Brandenburg began causing large numbers of human infections in New Zealand in 1998. We investigated the emergence of this strain using combined notification and laboratory data on human and animal disease and a case-control study. S. Brandenburg infection in humans was characterized by spring peaks and high rates in the southern half of the South Island. This epidemic pattern followed very closely that seen in sheep. The case-control study found that infection was significantly associated with occupational contact with sheep and having a household member who had occupational contact with sheep, during the 3 days prior to illness or interview. We conclude that S. Brandenburg has become established as a zoonotic disease in New Zealand. Preventing infection requires control of the epidemic in sheep through vaccination, changes in farm management practices, and promotion of hand washing and other precautions to protect farmers and their families.

Active surveillance for laboratory-confirmed Salmonella serotype Enteritidis (SE) infection revealed a decline in incidence in the 1990s, followed by an increase starting in 2000. We sought to determine if the fluctuation in SE incidence could be explained by changes in foodborne sources of infection. We conducted a population-based case-control study of sporadic SE infection in five of the Foodborne Diseases Active Surveillance Network (FoodNet) sites during a 12-month period in 2002–2003. A total of 218 cases and 742 controls were enrolled. Sixty-seven (31%) of the 218 case-patients and six (1%) of the 742 controls reported travel outside the United States during the 5 days before the case's illness onset (OR 53, 95% CI 23–125). Eighty-one percent of cases with SE phage type 4 travelled internationally. Among persons who did not travel internationally, eating chicken prepared outside the home and undercooked eggs inside the home were associated with SE infections. Contact with birds and reptiles was also associated with SE infections. This study supports the findings of previous case-control studies and identifies risk factors associated with specific phage types and molecular subtypes.

Non-typhoid Salmonella infections may present as severe gastroenteritis necessitating hospitalization and some patients become septic with bacteraemia. We hypothesized that the seasonal variation of non-typhoid Salmonella occurrence in humans diminishes with increased severity of infection. We examined the seasonal variation of non-typhoid Salmonella infections in three patient groups with differing severity of infection: outpatients treated for gastroenteritis (n=1490); in-patients treated for gastroenteritis (n=492); and in-patients treated for bacteraemia (n=113). The study was population-based and included all non-typhoid Salmonella patients in a Danish county from 1994 to 2003. A periodic regression model was used to compute the peak-to-trough ratio for the three patient groups. The peak-to-trough ratios were 4·3 [95% confidence interval (CI) 3·6–5·0] for outpatients with gastroenteritis, 3·2 (95% CI 2·4–4·2) for in-patients with gastroenteritis, and 1·6 (95% CI 1·0–2·8) for in-patients with bacteraemia. We conclude that the role of seasonal variation diminishes with increased severity of non-typhoid Salmonella infection.

Using isolates from reported cases of Escherichia coli O157 from Alberta, Canada in 2002, we applied randomization tests to determine if cases associated with an outbreak or statistical space–time cluster had more similar pulsed-field gel electrophoresis patterns, based on Dice coefficients, than expected by chance alone. Within each outbreak and space–time cluster, we assessed the mean, median, 25th percentile, 75th percentile, standard deviation, coefficient of variation, and interquartile range of the Dice coefficients of each pairwise comparison among the isolates. To assess the statistical significance of measures of location (e.g. mean) and variation (e.g. standard deviation) we created randomization distributions using all isolates or only isolates from sporadic cases. We determined that randomization tests are an appropriate tool for evaluating the similarity among isolates from cases that have been linked epidemiologically or statistically. We found little difference between using all cases or only sporadic cases when creating our randomization distributions.

Enterohaemorrhagic Escherichia coli O157 (O157) is infectious to humans, particularly children, at very low doses and causes not only haemorrhagic colitis but also other serious symptoms. To investigate an association between intestinal bacterial flora and resistance to such infections, we screened faecal samples for the presence of enteric bacteria that are able to suppress the growth of O157. Samples from 303 individuals, 35 children (aged [les ]6 years) and 268 adults (aged 20–59 years), were examined. Colonies with different appearances on sorbitol MacConkey agar medium were screened for the production of bacteriocins inhibitory for O157 in an overlay agar plate assay. O157-inhibiting strains were isolated from 52 individuals. The prevalence of these bacteria tended to rise with age, and was significantly higher among 40- to 59-year-old adults (23/101, 22·8%) than among children (3/35, 8·6%; P<0·05). To test the hypothesis that these bacteriocin-producing strains contribute to resistance against O157 in human adults, we examined faecal samples of 25 healthy O157 carriers. Inhibitory bacteria were more prevalent among the latter (9/25, 36·0%) than among age-matched subjects who did not carry O157 (49/268, 18·3%). It appears, therefore, that inhibitory bacteria in the human gut may play a role in inhibiting propagation of O157 and/or suppressing expression of virulence factors by this pathogen.

We examined the association between socioeconomic status and the level of serum antibodies to selected faeco-orally transmitted pathogens among Israeli adolescents. Random samples of eighty volunteers aged 12–15 years from high (HSL), medium (MSL) and low (LSL) standard of living towns were included in the study. Serum samples were examined by radioimmunoassay for HAV and by in-house-developed ELISA systems for IgA and IgG antibody levels against Shigella sonnei, S. flexneri, E. coli O157[ratio ]H7 lipopolysacchride and Cryptosporidium parvum antigens. Seropositivity to HAV was highest (98·8%) in the LSL towns and lowest (25%) in the HSL towns, showing a statistically significant linear trend. Antibody levels to the other enteropathogens had gender variation, with higher titres in females. Significantly lower titres in the HSL towns were found for: IgA anti-S. sonnei in females (P<0·001); IgG anti-S. sonnei in females (P=0·024) and males (P=0·033); IgG anti-S. flexneri in females (P=0·016). Inverse linear association with socioeconomic status was found for IgA anti-C. parvum in females (P<0·001); IgA anti-E. coli O157[ratio ]H7 in females (P<0·001) and males (P=0·024). A statistically significant association between HAV seropositivity and higher titres of IgA anti-S. sonnei and E. coli O157[ratio ]H7 was shown. In conclusion, exposure to enteropathogens transmitted via the faecal–oral route in communities of lower socioeconomic status is reflected in a higher prevalence of lifelong lasting antibodies to HAV, and higher levels of antibodies to bacterial and protozoan enteropathogens. Among females, the levels of specific serum antibodies are higher and more strongly associated with low socioeconomic status.

This study investigated 21 foodborne type-E botulism outbreaks, without antitoxin administration, from 1951 to 1965 in Hokkaido, Japan, to characterize the descriptive epidemiology and evaluate the relationship between case fatality and incubation period. The median (25–75% quartile) attack rate and case fatality, which were evaluated by outbreak, were 58·3% (38·0–73·2) and 25·7% (0·1–50·0) respectively. Individual records of 64 diagnoses, including 31 deaths, were also examined using logistic regression analysis, revealing that a shorter incubation period is likely to result in a significantly higher risk of death (P=0·01). The observed case fatality was more than 50% for those who developed symptoms within the first 18 h after exposure, possibly reflecting underlying dose-dependent mechanisms. In the event of intentional contamination of food with botulinum toxin, rapidly determining the incubation periods may be critical for guiding public health response efforts.

To evaluate the epidemiology of hospital admissions for varicella in children, a 1-year prospective multicentre study was done in Northern France in the pre-varicella vaccine era. The 405 children aged <16 years seen at local hospitals for varicella or herpes zoster were included. Among them, 143 who had varicella and resided in the district were admitted. Admission incidence rates were 28/100000 children aged <16 years (149/100000 infants aged <1 year, 69/100000 children aged 1–4 years, and 2/100000 children aged 5–15 years). Most admissions (57%) were related to complications, usually skin infection (47%). Independent risk factors for admission were place of residence outside the district [adjusted odds ratio (aOR) 8·7], complication at admission (aOR 5·8), recurrent fever (aOR 4·5), recent varicella in a sibling (aOR 4·0), and previous physician visit for the same condition (aOR 2·0).

Self-report of polysaccharide pneumococcal vaccination is not thought reliable because of the increased risk of adverse events from inadvertent re-vaccination in elderly people. Some studies suggest a high sensitivity of self-report and hence a low risk of adverse events if vaccination is administered when medical records are unavailable. Self-report of pneumococcal and influenza vaccination in a sample of >64-year-olds in the United Kingdom was compared with information in their medical records. Self-report of pneumococcal vaccination, in contrast to some of the other studies had a low sensitivity. The findings here support the need for accurate knowledge of prior vaccine status before offering the polysaccharide pneumococcal vaccine. The study also confirms that self-report of influenza vaccination could be relied upon if rapid knowledge of uptake is required.

Estimates of hepatitis C virus (HCV) clearance following acute infection range from 14 to 46%. This wide range is likely to be due to the characteristics of the populations studied and analysis methods. This paper examines how differing definitions of clearance parameters affect estimates of viral clearance in a cohort of 85 injecting drug users with newly acquired HCV infection. Kaplan–Meier estimates of time to HCV clearance were determined using varying definitions of eligible cohort, viral clearance, date of infection and date of clearance. Based on which combinations of definitions were used, the number of subjects eligible for analysis ranged from 27 to 75, clearance rate ranged from 14 to 68% and time to achieving 25% clearance ranged from approximately 5 months to 14 months. Standardized definitions and methodologies are required to enable valid comparisons of rates of clearance across newly acquired HCV infection natural history studies.