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.

This study documents the colonization of Staphylococcus aureus (SA), Streptococcus pneumoniae (SP) and specific resistant forms of these organisms among healthy children and identifies risk factors associated with these pathogens. Prospective point prevalence survey of nasopharyngeal specimens were obtained from 291 healthy children seeking routine well-child care at a university-based ambulatory paediatric clinic in a large urban city in the United States. A total of 291 children less than 5 years were enrolled during a 1-year period. Fifty-four (18·6%) were colonized with SA and 47 (16·2%) were colonized with SP. Among the 54 SA isolates, five (9·2%) were methicillin resistant (MRSA) and among the SP isolates, three (6·4%) were intermediate to penicillin (DRSP). Eighty per cent of all children enrolled reported no underlying medical condition. Care outside their home was more common among colonized (40·8%, 40/98) than non-colonized children (25·4%, 49/193), P=0·007. Healthy children from households of four or more people were also more likely to be colonized. The colonization rate of SA and SP among healthy children is consistent with what has been reported in the literature. The prevalence of MRSA and DRSP among healthy children colonized with SA or SP is low in this population of children attending a university-based ambulatory care centre in the United States.

In September 2003 a WHO consultation group on vaccine-derived polioviruses (VDPV) concluded that in order to prevent future generations of paralytic polio after interruption of transmission of wild poliovirus, the use of trivalent oral polio vaccine (OPV) must be stopped [1]. Another important global policy decision along the road to polio eradication thus became possible – cessation of OPV use at some time after eradication. The question now is not whether OPV must be stopped, but rather when.

It has come to our notice that a paper we published in Epidemiology & Infection contained a substantial amount of previously published material.

Salmonellosis is a global problem caused by the international movement of foods and high incidence in exporting countries. In September 2001, in an outbreak investigation Australia isolated Salmonella Stanley from imported peanuts, which resulted in a wider investigation in Canada, England & Wales and Scotland. Patients infected with Salmonella serotypes known to be isolated from peanuts and reported to surveillance systems were interviewed to determine exposure histories. Tagged image file format (TIFF) images of pulsed-field gel electrophoresis (PFGE) patterns of Salmonella isolates were shared electronically amongst laboratories. Laboratories tested packets of ‘Brand X’ peanuts from various lots and product lines. In total, 97 cases of S. Stanley and 12 cases of S. Newport infection were found. Seventy-three per cent (71/97) of S. Stanley cases were in persons of Asian ethnicity. Twenty-eight per cent of cases recalled eating Brand X peanuts and a further 13% had peanuts in their house in the previous month or had eaten Asian-style peanuts. Laboratories isolated S. Stanley, S. Newport, S. Kottbus, S. Lexington and S. Unnamed from Brand X peanuts. Isolates of S. Stanley from peanuts and human patients were indistinguishable by PFGE. This international outbreak resulted from a product originating from one country affecting several others. Rapid sharing of electronic DNA images was a crucial factor in delineating the outbreak; multinational investigations would benefit from a harmonized approach.

We investigated age- and gender-specific incidence of shingles reported in a large sentinel practice network monitoring a defined population over the years 1994–2001. In total, 5915 male and 8617 female incident cases were studied. For each age group, we calculated the relative risk of females to males presenting with shingles. Incidence rates of chickenpox and herpes simplex were examined similarly. Shingles incidence was greater in females in each age group (except for 15–24 years). Relative risks (female to male) were greatest in age groups 45–64 years (1·48) and 0–14 years (1·43). There were no gender differences in the incidence of chickenpox except in the 15–24 years age group (female excess): for herpes simplex there were female excesses in all age groups. Gender-specific age-standardized incidence rates of shingles were calculated for each year and showed a consistent female excess in each of the 8 years (average annual excess 28%).

We conducted a survey to determine the accuracy of the clinical diagnosis of measles in Zimbabwe. Between December 1996 and February 1997, we collected blood samples and clinical and demographic information from a sample of 105 children with a clinical diagnosis of measles. A clinical case of measles was defined as a person with a history of fever, rash for three or more days, and either cough, coryza, or conjunctivitis. A laboratory-confirmed case of measles or rubella had IgM antibodies against measles virus or rubella virus respectively. A total of 91% of children met the clinical case definition. Among those who met the clinical case definition for measles, 72% were IgM-positive for measles virus only, 23% were IgM-positive for rubella virus only, 3% were IgM-positive for both measles and rubella viruses, and 2% were IgM-negative for both viruses. This study demonstrates the importance of considering selective laboratory confirmation of measles in periods of high disease incidence when the effectiveness of the vaccine is questioned.

Severe acute respiratory syndrome (SARS) struck Hong Kong bitterly in the spring of 2003, infecting 1755 persons and claiming nearly 300 lives. The epidemic was introduced by travellers from southern China, where the disease had originated. It started in late February and lasted until early June. Two notable ‘super-spreading’ events were reported, one inside a teaching hospital and the other in a private housing estate. Other than in the super-spreading events, the infectivity in the community appeared to be low, and there were few, if any, asymptomatic or subclinical infections. Health-care workers were at particular risk and accounted for 22% of all probable cases. The main modes of transmission were through droplet spread and close/direct contacts, but situations conducive to aerosol generation appeared to be associated with higher risk. Our review suggests that there are still many unknown factors concerning the mode of transmission and environmental risk that need to be clarified.

Hepatitis A virus (HAV) is spread by faecal–oral contact or ingestion of contaminated food or water. Lifelong immunity is conferred by infection or vaccination, so anti-HAV seroprevalence studies can be used to indicate which populations are susceptible to infection. Seroprevalence rates are highly correlated with socioeconomic status and access to clean water and sanitation. Increasing household income, education, water quality and quantity, sanitation, and hygiene leads to decreases in HAV prevalence. Japan, Australia, New Zealand, Canada, the United States, and most European nations have low anti-HAV rates. Although anti-HAV rates remain high in most Latin American, Asian, and Middle Eastern nations, average seroprevalence rates are declining. Surveys from Africa generally indicate no significant decline in anti-HAV rates. Because the severity of illness increases with age, populations with a high proportion of susceptible adults should consider targeted vaccination programmes.

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.

We report the clinical, microbiological, and epidemiological features of an emerging serotype, Shigella boydii 20. We interviewed patients about symptoms, and history of travel and visitors during the week before illness onset. Seventy-five per cent of the 56 patients were Hispanic. During the week before illness onset, 18 (32%) travelled abroad; 17 (94%) had visited Mexico. Eight (21%) out of 38 who had not travelled had foreign visitors. There were eight closely related patterns by PFGE with XbaI. S. boydii 20 may be related to travel to Mexico and Hispanic ethnicity. Prompt epidemiological investigation of clusters of S. boydii 20 infection may help identify specific vehicles and risk factors for infection.

A total of 4624 pneumococcal isolates from episodes of systemic pneumococcal disease were received at the Norwegian Institute of Public Health during the period 1995–2001. All isolates were serotyped and tested for susceptibility to benzylpenicillin, lincomycin, erythromycin, tetracycline and trimethroprim–sulphamethoxazole. The proportion of strains resistant to these antimicrobial agents remained stable at a low level, ranging from 0·1% for benzylpenicillin to 2·5% for erythromycin. The distribution of serotypes was also stable over the 7 years: serotypes 1, 4, 9, 14, 7, 6 and 23 were the most frequent, representing 70·5% of isolates. Overall, 95·8% of the isolates were of serotypes/groups included in the current 23-valent polysaccharide vaccine, 52·2% were of serotypes/groups included in the 7-valent conjugated vaccine and 85·5% were of serotypes/groups included in the 11-valent conjugated vaccine.

A serological prevalence survey was carried out in Luxembourg during 2000–2001 to determine the antibody status of the Luxembourg population against vaccine-preventable infections. Blood samples of children and adolescents were collected prospectively in randomly selected schools. Samples of adults were obtained through volunteer patients of the national health laboratory or of the mandatory pre-nuptial test. Measles, mumps and rubella (MMR) virus antibody concentrations were measured using commercial ELISA tests. Age-standardized prevalence of measles, mumps and rubella virus antibodies was found to be 96·58, 75·40 and 95·69% respectively. Significant age-dependence of serology was observed for all three infections, with study participants born after the introduction of the MMR vaccine experiencing a gradual decline of antibodies following vaccination in childhood. Older study participants who were more likely to have antibodies from natural infection had consistently higher titres than younger individuals. Present vaccination coverage with MMR appears to be sufficient to prevent large local outbreaks of measles and rubella, but probably not mumps.

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.

We explored the dual influence of the patient's age and the infecting serotype on the blood invasiveness patterns of non-Typhi Salmonella enterica (NTS). Blood invasiveness ratio (BIR) was calculated as the ratio between the number of blood and blood+stool isolates. Analysis of 14951 NTS isolates showed that the BIR increased drastically above the age of 60 years, reaching levels 3·5–7 times higher compared to age group <2 years. Different patterns of age-related invasiveness were observed for the five most common NTS serotypes (Enteritidis, Typhimurium, Virchow, Hadar, Infantis). Among children <2 years, the BIR was highest for serotype Virchow and lowest for serotype Hadar, while in persons [ges ]60 years it was highest for serotypes Enteritidis and lowest for serotype Infantis. The tendency of NTS serotypes to invade the bloodstream was significantly influenced by the patient's age, however the impact of age differed for various NTS serotypes.

PspA is an antigenically variable virulence factor of Streptococcus pneumoniae that inhibits complement deposition and is a potential candidate for human vaccines. Of 64 published strains 96% are in PspA families 1 and 2; optimal protection is family-specific. Effective development of a PspA-containing vaccine requires more information about the PspA family of strains in parts of the world where the vaccine is most needed. In these studies we observed that of 149 isolates (of 19 capsular types) from Argentina, 54·4% were family 1, 41·6% were family 2 and 4·0% expressed both family 1 and family 2 PspAs. Box typing revealed the Argentinian strains to be from at least 10 clonally related groups.

Fourier time-series models were constructed to study regional and national seasonality of human campylobacteriosis in Scotland between 1997 and 2001. Strong seasonality was demonstrated with an annual peak of reported cases in late June to early July. The prominence of this peak varied between regions, which was exemplified for the two major population centres: Lothian, with mixed urban/rural population, had a more prominent peak than Greater Glasgow, which has a predominantly urban population. No significant trend of annual cases of campylobacteriosis was found nationally and Fourier models successfully predicted the seasonal pattern of national and regional cases in 2002. During the period studied, the Fourier model identified >20 bursts of infection (potential outbreaks). Multi-regional bursts were also identified in the summers of 1998 and 2000 – the latter comprising the vast majority of the regions in Scotland, which could suggest a national outbreak.

To assess areas at risk for poliovirus circulation in Ecuador, we first selected provinces at highest risk based on low immunization coverage with three doses of oral poliovirus vaccine, and a low number of reported cases of acute flaccid paralysis (AFP). Subsequently, we reviewed discharge data for the period 1996–2000 for diagnoses compatible with AFP in the only two national referral hospitals in Quito, and at least two main hospitals in each of the six selected provinces. Environmental samples from one or two cities/towns in each selected province were tested for poliovirus. Of the 14 identified AFP-compatible cases, 8 (57%) had been previously reported and investigated. We visited four out of the six unreported cases; none of those four had sequelae compatible with poliomyelitis. From the 14 environmental samples taken, we identified Sabin viruses in six of the samples; no vaccine-derived polioviruses were isolated. Using this methodology, we found no evidence of undetected poliovirus circulation in Ecuador.

Between 1 and 22 March 2003, a nosocomial outbreak of Severe Acute Respiratory Syndrome (SARS) occurred at the Communicable Disease Centre in Tan Tock Seng Hospital, Singapore, the national treatment and isolation facility for patients with SARS. A case-control study with 36 cases and 50 controls was conducted of factors associated with the transmission of SARS within the hospital. In univariate analysis, contact with respiratory secretions elevated the odds ratio to 6·9 (95% CI 1·4–34·6, P=0·02). Protection was conferred by hand washing (OR 0·06, 95% CI 0·007–0·5, P=0·03) and wearing of N95 masks (OR 0·1, 95% CI 0·03–0·4, P=0·001). Use of gloves and gowns had no effect. Multivariate analysis confirmed the strong role of contact with respiratory secretions (adjusted OR 21·8, 95% CI 1·7–274·8, P=0·017). Both hand washing (adjusted OR 0·07, 95% CI 0·008–0·66, P=0·02) and wearing of N95 masks (adjusted OR 0·1, 95% CI 0·02–0·86, P=0·04) remained strongly protective but gowns and gloves had no effect.

The drug susceptibility and genes responsible for the drug resistance of Vibrio cholerae O1 isolated in Vietnam in 1995, 2000 and 2002 were studied. The strains isolated in 1995 were resistant to streptomycin and harboured the class I integron which contained the aadA1 gene responsible for streptomycin resistance. The strains isolated in 2000 were devoid of a class I integron but were multiple-drug resistant and harboured SXT constin, with several drug-resistant genes. The genes responsible for streptomycin resistance were strA and strB. The strains isolated in 2002 were sensitive to all drugs examined, and the organisms were devoid of both class I integron and SXT constin. Cholera outbreaks in the three periods examined (1995, 2000 and 2002) were apparently due to different categories of V. cholerae O1.