Pityriasis rosea, first named as such in 1860, probably holds the longest record for an exanthem suspected to be associated with an infection but for which an exact cause has not been found. The distinctly programmed clinical course, the lack of recurrence for most patients, and the presence of temporal case clustering provide the strongest evidence to support an infectious aetiology. Further support comes from seasonal variation and the association with respiratory tract infections, the unfavourable social and economic background of cases, and a history in some cases of contact with patients with pityriasis rosea. The apparent therapeutic efficacy of several treatment modalities does not provide strong evidence for or against an infectious aetiology. The roles of human herpesvirus 7 and to a lesser extent human herpesvirus 6 remain controversial. There exists reasonable evidence that pityriasis rosea is not associated with cytomegalovirus, Epstein–Barr virus, parvovirus B19, picornavirus, influenza and parainfluenza viruses, Legionella spp., Mycoplasma spp. and Chlamydia spp. infections. Evidence is also unsubstantiated as yet for alternative aetiological hypotheses such as autoimmunity, atopy, and genetic predisposition.

In Victoria (Australia) surveillance for mumps and rubella has historically been passive, with most notified cases clinically diagnosed. In July 2001, the Victorian Department of Human Services implemented an enhanced surveillance system focusing on improved laboratory testing. We tested 85% of notifications and only 9% of all mumps and 27% of rubella notifications were laboratory confirmed. While most notified cases were children who had been clinically diagnosed, we found most laboratory-confirmed cases were in adults. The positive predictive value of the clinical case definition was low: mumps (10%); rubella (22%). These results highlight the value of laboratory confirmation of the diagnosis when mumps and rubella are rare, failure to do so is likely to overestimate disease incidence.

Sera from 27 children and eight older persons, which had been collected in 1998 and 1999 and showed haemagglutination–inhibition (HI) activity against influenza A/Sydney/5/97 (H3N2) strain, were characterized with a binding assay using chimeric haemagglutinin (HA) proteins between A/Aichi/2/68 (A/AI/68) and A/Sydney/5/97 (A/SD/97) strains. Sera from the young children had a tendency to recognize only the antigenic site B1 of the HA1 region. On the other hand, sera of the older individuals were fully reactive to all antigenic sites of HA1 except antigenic site D. Recent epidemic strains, A/Panama/2007/99 (A/PM/99)-like viruses have differences in amino acids in antigenic sites A, C, and B2 but not B1. However, human antisera obtained even from young children had HI activity to Panama-like viruses. The limited epidemic of A/PM/99-like viruses may have been due to the existence of antibody against B1, which had been produced in response to infection by the A/SD/97-like viruses.

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.

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.

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.

A retrospective population-based study was conducted between January 1990 and December 1998 to investigate the incidence of Mycobacterium kansasii disease and the heterogeneity of the isolates in a well-defined geographical area in Catalonia, Spain. A total of 136 patients were identified. Overall incidence and incidence in AIDS patients was 1·5 (95% CI 1·2–1·8) and 1089·6 (95% CI 689–1330) cases/100000 persons per year respectively, which is comparable to that reported from most of other geographical areas. Surprisingly, although 7 subtypes of M. kansasii have been consistently reported, in the present study 91 of the 93 isolates (97·8%) tested for genotype were subtype I, regardless of HIV status of the patients. In conclusion, the high rate of infection observed in the AIDS population contributes significantly to the burden of the M. kansasii disease in our area. M. kansasii disease in our geographical area was almost exclusively caused by subtype I regardless of HIV status.

This paper analyses Streptococcus pneumoniae transmission dynamics in households using longitudinal data on pneumococcal (Pnc) carriage in the United Kingdom. Ten consecutive swabs were taken at 4-week intervals from all members of 121 households. The family status is derived from the observed Pnc carriage status of each family member. Transition matrices are built for each family size and composition containing the observed frequency of transitions between family statuses over a 28-day interval. A density-dependent transmission model is fitted to derive maximum-likelihood estimates of the duration of carriage and acquisition rates from the community and from infected individuals within the household. Parameter values are estimated for children (<5 years) and adults (5+ years). The duration of carriage is longer in children <5 years of age than in older family members (51 vs. 19 days). Children are 3–4 times more likely than adults to acquire Pnc infection from the community. Transmission rates within the household suggest that adults are more infectious but less susceptible than children. Transmission within the household is most important in large families. The proportion of household-acquired infection ranges from 29 to 46% in households of three persons to 38–50% in larger households. Evidence of density-dependent within-household transmission is found, although the strength of this relationship is not clear from the model estimates.

We investigated the relationship between environmental temperature and reported Salmonella infections in 10 European populations. Poisson regression adapted for time-series data was used to estimate the percentage change in the number of cases associated with a 1 °C increase in average temperature above an identified threshold value. We found, on average, a linear association between temperature and the number of reported cases of salmonellosis above a threshold of 6 °C. The relationships were very similar in The Netherlands, England and Wales, Switzerland, Spain and the Czech Republic. The greatest effect was apparent for temperature 1 week before the onset of illness. The strongest associations were observed in adults in the 15–64 years age group and infection with Salmonella Enteritidis (a serotype of Salmonella). Our findings indicate that higher temperatures around the time of consumption are important and reinforce the need for further education on food-handling behaviour.

In the summer of 1999 a cluster of 18 cases of necrotizing enterocolitis (NEC) occurred in a University Hospital in Rome, Italy. The cases presented with mild clinical and radiological signs, and none died. Seventy-two per cent had a birth weight of >2500 g, 66·7% had a gestational age of >37 weeks, 30% presented with respiratory diseases and/or hypoglycaemia. All cases occurred within 10 days of birth and between 5 and 7 days after two clusters of diarrhoea (14 cases). The NEC outbreak had two phases; most cases in the first phase occurred in the at-risk unit, whereas those in the second phase occurred in the full-term unit. In the multivariate analysis, invasive therapeutic procedures, pathological conditions and formula feeding were associated with NEC. Although no predominant common bacteria were isolated, we suggest an infective origin of this outbreak.

Surveys carried out between 1990 and 2000 indicated that the incidence of STEC O157-associated gastroenteritis in The Netherlands was 1250 cases/year (median), of which 180 visited a general practitioner, 40 are reported and 0·6 are fatal, mainly in the elderly. There are approximately 20 cases of STEC O157-associated haemolytic–uraemic syndrome (HUS) per year, mainly in children. There are 2·5 HUS patients per year who develop end-stage renal disease (ESRD). There are an estimated 2 HUS-related and 0·5 ESRD-related fatalities per year. The mean disease burden associated with STEC O157 in the Dutch population is 116 (90% confidence interval 85–160) Disability Adjusted Life Years (DALYs) per year. Mortality due to HUS (58 DALYs), and ESRD (21 DALYs) and dialysis due to ESRD (21 DALYs) constitute the main determinants of disease burden. Sensitivity analysis indicates that uncertainty associated with model assumptions did not have a major effect on these estimates.

To identify risk factors for sporadic Salmonella Typhimurium definitive phage-type 104 (DT104) and non-DT104 diarrhoeal illness in Canada, we conducted a matched case-control study between 1999 and 2000. Cases were matched 1[ratio ]1 on age and province of residence. Multivariate analysis suggested that recent antibiotic use [odds ratio (OR) 5·2, 95% confidence interval (CI) 1·8–15·3], living on a livestock farm (OR 4·9, 95% CI 1·9–18·9), and recent travel outside Canada (OR 4·1, 95% CI 1·2–13·8) are independent risk factors for DT104 illness. Similar analyses suggested that recent travel outside North America is a sizable risk factor for non-DT104 illness (OR 66·8, 95% CI 6·7–665·3). No food exposure was a risk factor in either analysis. Educating health-care providers and the public about appropriate antibiotic use and antimicrobial resistance is important. Appropriate administration of antibiotics to livestock, particularly cattle, and hygienic measures such as handwashing after contact with farm animals may reduce risk. Travel represents an important and probably underestimated risk factor for sporadic illness with S. Typhimurium. Improved national surveillance and detailed investigation of travel-related illness are required.

This article describes the spatial and temporal distribution of verotoxin-producing Escherichia coli among humans (EHEC) and cattle (VTEC) in Sweden, in order to evaluate relationships between the incidence of EHEC in humans, prevalence of VTEC O157 in livestock and agricultural structure by an ecological study. The spatial patterns of the distribution of human infections were described and compared with spatial patterns of occurrence in cattle, using a Geographic Information System (GIS). The findings implicate a concentration of human infection and cattle prevalence in the southwest of Sweden. The use of probability mapping confirmed unusual patterns of infection rates. The comparison of human and cattle infection indicated a spatial and statistical association. The correlation between variables of the agricultural structure and human EHEC incidence was high, indicating a significant statistical association of cattle and farm density with human infection. The explained variation of a multiple linear regression model was 0·56.

An epidemiological and molecular investigation of a cutaneous suppurative infection with Staphylococcus aureus in a dairy farmer, occurring concurrently with an outbreak of clinical mastitis in his herd, was carried out. A common aetiology for the diseases in the farmer and his cows was established by combining clinical evidence with a molecular genomic analysis of the bacterial isolates using pulsed field gel electrophoresis of DNA macro-restriction fragments. This case indicates the possibility of the emergence and circulation of anthropozoonotic clones of S. aureus in dairy herds. It also provides further evidence of the severe impact of infection with highly virulent clones on dairy lactating cattle.

An epidemiological model was developed for rabies, linking the risk of disease in a secondary species (cats) to the temporal dynamics of disease in a wildlife reservoir (raccoons). Data were obtained from cats, raccoons, and skunks tested for rabies in the northeastern United States during 1992–2000. An epizootic algorithm defined a time-series of successive intervals of epizootic and inter-epizootic raccoon rabies. The odds of diagnosing a rabid cat during the first epizootic of raccoon rabies was 12 times greater than for the period prior to epizootic emergence. After the first raccoon epizootic, the risk for cat rabies remained elevated at levels six- to seven-fold above baseline. Increased monthly counts of rabid raccoons and skunks and decreasing human population density increased the probability of cat rabies in most models. Forecasting of the public health and veterinary burden of rabies and assessing the economics of control programmes, requires linking outcomes to dynamic, but predictable, changes in the temporal evolution of rabies epizootics.

Thirty-one viruses causing SAT-2 outbreaks in seven West African countries between 1974 and 1991, and four viruses representative of East and Central Africa were genetically characterized in this study. Four major viral lineages (I–IV) were identified by phylogenetic analysis of an homologous 480 nucleotide region corresponding to the C-terminus end of VP1. Lineage I comprised two West African genotypes with viruses clustering according to year of isolation rather than geographical origin. Lineage II was represented by viruses isolated between 1979 and 1983 in two neighbouring West African countries, Senegal and The Gambia. Viruses from Nigeria and Eritrea, representative of West and East Africa respectively, constituted lineage III, whilst lineage IV, comprising viruses from Central and East Africa, was regionally and genetically distinct. This study revealed that unrestricted animal movement in West Africa is a major factor in disease dissemination and has also provided the first indication of trans-regional virus transmission.

Isolated reports of brucellosis among family members have been documented. The aim of this study is to determine if active serological screening of the households' members of acute brucellosis cases will detect additional unrecognized cases. From May 2000 to October 2001, patients with acute brucellosis were enrolled and their household members were serologically screened for brucellosis using the Standard Agglutination Test (SAT). Fifty-five index cases with acute brucellosis and 404 household members were enrolled. The majority of index cases (48%) were young adults, and 79% were illiterate. Ownership of animals and ingestion of unpasteurized raw milk were reported by 45 and 75% of the index cases respectively. Of the 55 families screened, 23 (42%) had two family members or more with serological evidence of brucellosis and 32 (58%) had only the index case. Households of [ges ]5 members and a history of raw-milk ingestion by family members were risk factors associated with the seropositives (P<0·05). Of the 404 household members screened, 53 (13%) were seropositive; of these 39 (74%) were symptomatic, and 9 (35%) had brucella bacteraemia. Symptomatic seropositives tended to have bacteraemia and higher brucella antibody titres compared to asymptomatic seropositives (P[les ]0·05). Screening family members of an index case of acute brucellosis will detect additional cases.

We followed up a cohort of 446 toxoplasma-infected pregnant women to determine the median and variability of the duration of positive toxoplasma–IgM (immunoglobulin M) results measured by an immunofluorescence test (IFT) and an immunosorbent agglutination assay (ISAGA). IgM antibodies were detected for longer using the ISAGA test [median 12·8 months, interquartile range (IQR) 6·9–24·9] than the IFT (median 10·4, IQR 7·1–14·4), but the variability between individuals in the duration of IgM positivity was greatest for the ISAGA test. IgM-positive results persisted beyond 2 years in a substantial minority of women (27·1% ISAGA, 9·1% IFT). Variation in the duration of the IgM response measured by ISAGA and IFT limit their usefulness for predicting the timing of infection in pregnant women. However, measurement of IgM and IgG antibodies in a cross-sectional serosurvey offers an efficient method for estimating the incidence of toxoplasma infection.

Puumala virus (PUUV) is the causative agent of nephropathia epidemica, a mild form of haemorrhagic fever with renal syndrome. PUUV is transmitted to humans via aerosolized excreta of the infected bank vole (Clethrionomys glareolus). Current methods for screening of the PUUV prevalence among bank vole populations are laborious, combining sampling in the field and subsequent analyses in the laboratory. In order to facilitate animal testing, a new serological immunochromatographic rapid test was developed. The test uses PUUV nucleocapsid protein as antigen, and it detects anti-PUUV IgG antibodies in rodents. With fresh and undiluted bank-vole blood samples (n=105) the efficacy of the test was 100%, and with frozen and diluted samples (n=78) the efficacy was 91%. The test was also shown to detect related hantavirus infections in Norway lemmings and sibling voles (n=31) with 99% efficacy. The test provides an applicable tool for studying PUUV and related hantavirus infections in arvicoline rodents.

Rabbit haemorrhagic disease virus (RHDV) has killed many millions of wild rabbits in Europe and Australia, but has had little impact in the United Kingdom, despite outbreaks having occurred since 1994. High seroprevalence detected in the absence of associated mortality had suggested the presence of an endemic non-pathogenic strain which may be ‘protecting’ UK populations. Following the first detailed field study of RHDV epidemiology in the United Kingdom, using mark–recapture with serum sampling, we report that RHDV caused highly prevalent persistent infection in seropositive rabbits in the absence of associated mortality. Furthermore the virus strains responsible could not be distinguished phylogenetically from known pathogenic isolates, and were clearly very different from the only previously identified non-pathogenic strain of RHDV. These findings suggest that many – perhaps most – strains of RHDV may be propagated through both ‘pathogenic’ and ‘non-pathogenic’ modes of behaviour. Transmission occurred predominantly during and just after the breeding season.