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.

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.

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.

This paper describes the epidemiology of a syphilis outbreak in remote Australia, and explores contributing factors and control strategies. Between 1 August 2000 and 31 January 2002, 74 cases of early syphilis (42 female, 32 male) were identified in 73 Kimberley residents. Syphilis rates in age groups 10–19 and 20–29 years were 583 and 439 per 100000 person years respectively. Factors contributing to the outbreak included incompleteness of sexually transmitted infection (STI) clinical management, untimely contact tracing, staffing and management issues, and poor community knowledge about STIs. Outbreak control strategies addressed factors that could be influenced by changes in health service delivery, and focused on providing education and support to health staff, and efforts to increase community knowledge about sexual health. Although some improvements have occurred, the outbreak is still continuing. Until open and honest discussion and a collaborative approach is taken toward STI problems affecting Indigenous Australians, outbreaks such as this will continue to occur.

An environmental surveillance programme was developed to determine whether water supplies could be a source of Burkholderia pseudomallei as noted during previous melioidosis outbreak investigations. Water supplies to communities in the three northern Australian jurisdictions (Western Australia, Northern Territory and Queensland) were sampled periodically during 2001 and 2002. Water and soil samples were collected from communities known to have had recent culture-positive melioidosis cases and nearby communities where no cases had been diagnosed. Clinical isolates of B. pseudomallei obtained from northern Australian patients during 2001 and 2002 were compared with the environmental B. pseudomallei isolates by ribotyping and pulsed-field gel electrophoresis. B. pseudomallei was isolated from 11 distinct locations, all in the Northern Territory, seven of which were associated with culture-positive melioidosis cases (>1 case at three locations). Water was implicated as a possible environmental source of melioidosis in six locations. A variety of free-living amoebae including Acanthamoeba and Hartmannella spp. that are potential hosts to B. pseudomallei were recovered from environmental specimens. Culturable B. pseudomallei was not found to be widely dispersed in the environments sampled.

We did a retrospective study of 1920 episodes of community-acquired pneumonia (CAP) in 27 community hospitals and analysed inter-hospital variability in length of hospital stay (LOS), mortality and readmission rates. The overall adjusted LOS (mean±S.D.) was 10·0±9·8 days. LOS increased according to the Pneumonia Severity Index (PSI) risk class: 7·3 days for class I to 11·3 days for class V (P<0·001). In a multiple regression model, LOS increased (P<0·001) according to the hospital (inter-hospital variability), PSI risk class, complications during hospitalization, admission to ICU, need of oxygen and transfer to a nursing home. Hospitals with shorter LOS did not show an increased readmission rate (adjusted OR 1·02, 95% CI 0·51–2·03, P=0·97) and post-discharge mortality (adjusted OR 1·20, 95% CI 0·70–2·05, P=0·51). There are significant inter-hospital variations in LOS in patients with CAP which are related to differences in clinical management. The reduction of these differences will further improve efficiency and quality of care.

Staphylococcus aureus is a common human pathogen in community- and hospital-acquired infections and its capsule is involved in pathogenesis. We report here the identification of type-5 and type-8 capsular antigens of S. aureus and the prevalence of such strains among volunteers in various age and population groups from different locations in India. S. aureus carriage rates varied between 18 and 50% with the highest values among university students and the lowest in schoolchildren, aged 6–20 years. There was no difference in carriage rates for males vs. females (P=0·415) or in the socioeconomic status of carriers vs. non-carriers or age dependence. Among the carriage isolates 21% were type-5, 52% were type-8 and the remaining 27% were non-typable. Among invasive isolates these percentages were 6, 64 and 30 respectively. This implies that type-5 strains may be less invasive than type-8 strains (P=0·0015).

During 1995–1996 a population-based seroprevalence study was conducted in The Netherlands. Risk factors were established for postnatally acquired toxoplasmosis. The results were compared with a study conducted during 1987–1988 in pregnant women in the Southwest of The Netherlands in order to estimate the change in seroprevalence. In total, 7521 sera were tested and the national seroprevalence was 40·5% (95% CI 37·5–43·4). Living in the Northwest, having professional contact with animals, living in a moderately urbanized area, being divorced or widowed, being born outside The Netherlands, frequent gardening and owning a cat were independently associated with Toxoplasma seropositivity. Risk factors like eating undercooked meat could not be studied. The seroprevalence among women aged 15–49 years was 10% lower (35·2%, 95% CI 32·9–38·6) in the study of 1995–1996, compared to the Toxoplasma study of 1987–1988 (45·8%, 95% CI 45·2–46·3). The steepest rise in seroprevalence still occurred among the subjects aged 25–44 years.

The purpose of the study was to detect the frequency and distribution of Helicobacter pylori in the Gülveren Health Centre service area among residents aged between 25 and 64 years and to evaluate the relation of H. pylori infections with general health status, socioeconomic status, and some lifestyle habits. The study included a representative sample of Gülveren Health Centre residents, aged between 25 and 64 years. A stratified random sample of 1672 individuals was selected for study purposes out of 10569 residents, stratified by age and gender. A standardized questionnaire was completed for all study participants using a face-to-face interview and all participants were invited to the local health centre for a thorough physical examination and blood tests. The overall prevalence of H. pylori was found to be 77·5% among individuals aged between 25 and 64 years. The frequency of H. pylori was higher among individuals with low socioeconomic status; those who migrated to Ankara after the age of 20 years; members of large families (household size of 4 or above); non-alcohol drinkers; and those who regularly drink tea.

Serum samples from 446 Italian blood donors between 18 and 65 years of age were analysed for the presence of IgG against parvovirus B19 capsid proteins VP1 and VP2 including conformational and linear epitopes. The overall prevalence of IgG against parvovirus B19 capsid proteins VP1 and VP2 against at least one antigen type was 79·1%. No significant difference was found between men and women. In the 18–27 years age group, 77·0% of the population had experienced infection with the virus, reaching 88·5% in the 48–57 years age group. The overall prevalence of IgG was 78·0% against conformational VP1+VP2 antigens, 74·9% against conformational VP2, 70·9% against linear VP1 and 23·3% against linear VP2 in the analysis of the IgG response against different conformational and linear epitopes of VP1 and VP2. Although IgG against conformational VP1+VP2, conformational VP2 and linear VP1 was present in more than 60% of subjects in all age groups, IgG against VP2 linear antigens was present in only 32% of subjects in the 18–27 years age group and then decreased to 20·5% in the 28–37 years age group. A different trend was noted when IgG positivity against linear and conformational epitopes was analysed separately in men and women. A significant increase was found in seroprevalence of IgG against VP2 conformational antigens with increasing age in males and a significant decrease in seroprevalence of IgG against VP2 linear antigens in women with increasing age.

In a previous risk factor study in Jakarta we identified purchasing street food as an independent risk factor for paratyphoid. Eating from restaurants, however, was not associated with disease. To explain these findings we compared 128 street food-vendors with 74 food handlers from restaurants in a cross-sectional study in the same study area. Poor hand-washing hygiene and direct hand contact with foods, male sex and low educational level were independent characteristics of street vendors in a logistic regression analysis. Faecal contamination of drinking water (in 65% of samples), dishwater (in 91%) and ice cubes (in 100%) was frequent. Directly transmittable pathogens including S. typhi (n=1) and non-typhoidal Salmonella spp. (n=6) were isolated in faecal samples in 13 (7%) vendors; the groups did not differ, however, in contamination rates of drinking water and Salmonella isolation rates in stools. Poor hygiene of street vendors compared to restaurant vendors, in combination with faecal carriage of enteric pathogens including S. typhi, may help explain the association found between purchasing street food and foodborne illness, in particular Salmonella infections. Public health interventions to reduce transmission of foodborne illness should focus on general hygienic measures in street food trade, i.e. hand washing with soap, adequate food-handling hygiene, and frequent renewal of dishwater.

A Salmonella Enteritidis (SE) outbreak in Japan was investigated with an observational study, analytical epidemiology and bacteriological examination (including phage typing). The outbreak occurred among 96 schoolchildren, and was caused by SE phage type 1. The outbreak source was dessert buns served at a school lunch (RR 42·55, 95% CI 5·93–305·11, P<0·001). The buns were probably cross-contaminated from eggs from a factory with a history of SE-contaminated products. The incubation period was longer than usual (3–16 days, median 8 days). A low contaminating dose may account for the long incubation period and low attack rate. Outbreak detection was hampered by the absence of routine Salmonella surveillance in Japan. The investigation was complicated by concurrent illnesses from other SE phage types. It was successful, in part, because adequate food samples were available for microbiological testing.

Salmonella Goldcoast (SGC), an uncommon serotype in Germany, was identified in 25 isolates between 1 April and 7 May 2001. To determine the cause of the outbreak, we conducted a matched case-control study including 24 cases and 51 controls. In a multivariable regression model, only consumption of a raw fermented sausage manufactured by a local company remained significant (adjusted odds ratio 20·0, 95% confidence interval 2·7–302·5). SGC isolated from case-patients shared an indistinguishable pulsed-field gel electrophoresis pattern. A part of the produced raw fermented sausage was sold after only 4 days of fermentation. Samples from the premises and products of the company were negative for SGC. However, short-time raw fermented sausage is more likely to contain pathogens. Irradiation of raw ingredients is not accepted by German consumers, thus strict adherence to good manufacturing practices, the use of HACCP programmes as well as on-farm programmes remain crucial to reduce Salmonella.

In Europe, the number of reported sporadic human cases of Salmonella Livingstone infection is low, and outbreaks are rare. We report the largest S. Livingstone outbreak described in the literature having an identified source of infection. In February 2001, an increased incidence of infection caused by S. Livingstone was observed in Norway and Sweden. By July 2001, 44 cases were notified in Norway and 16 in Sweden. The median age was 63 years, and 40 were women. There were three deaths, and 22 patients were hospitalized. Based on standardized questionnaires and retrospective studies of S. Livingstone strains in Norway and Sweden, food items with egg powder were suspected, and S. Livingstone was subsequently recovered from a processed fish product at the retail level. Analysis by pulsed-field gel electrophoresis documented that isolates from the fish product belonged to the same clone as the outbreak strain.

Salmonellosis is a major cause of gastroenteritis in the United States and can lead to septicaemia, and other extra-intestinal illness including urinary tract infections (UTIs). To examine trends in Salmonella bacteriuria in the United States, surveillance data from the National Salmonella Surveillance System from 1980 to the end of 1999 were reviewed. Overall, 17442 urinary Salmonella isolates were reported, representing 2% of all Salmonella isolates from a known source. This proportion increased from 2% during 1980–1984 to 4% during 1995–1999. The median age of persons from whom these isolates came was 51 years; 12176 (70%) were women. Compared to the last national survey conducted between 1968 and 1979, the rate of Salmonella bacteriuria increased among women, from 2·0 per million persons in 1980 to 3·7 in 1999; the highest rate occurring in women [ges ]70 years. National reporting of Salmonella bacteriuria increased in absolute incidence and as a proportion of all Salmonella, especially in elderly women and may represent an increase in the incidence of Salmonella UTIs. Better understanding of the uropathogenicity of Salmonella serotypes may further clarify the mechanisms of Salmonella UTIs.

Surveillance and control are important aspects of food safety assurance strategies at the pre-harvest level of pork production. Prior to implementation of a Salmonella surveillance and control programme, it is important to have knowledge on the dynamics and epidemiology of Salmonella infections in pig herds. For this purpose, 17 finishing pig herds initially classified as seropositive and 15 as seronegative, were followed for a 2-year period through serological and bacteriological sampling. The study included 10 herds from Denmark, 13 from The Netherlands, 4 from Germany and 5 from Sweden and was performed between October 1996 and May 1999. The Salmonella status of finishing pig herds was determined by an initial blood sampling of approximately 50 finishing pigs close to market weight per herd. The development of the Salmonella status of the selected herds was assessed at seven subsequent sampling rounds of 25 blood samples from finishing pigs, 25 blood samples from grower pigs and 10 pen faecal samples each, approximately 3 months apart. The odds for testing finishers seropositive, given that growers were found seropositive previously were 10 times higher than if growers were seronegative (OR 10·0, 95% CI 3·2–32·8). When Salmonella was isolated from pen faecal samples, the herd was more likely to be classified seropositive in the same sampling round, compared to no Salmonella being detected (OR 4·0, 95% CI 1·1–14·6). The stability of an initially allocated Salmonella status was found to vary noticeably with time, apparently irrespective of a seropositive or seronegative classification at onset of the study. Given the measured dynamics in the occurrence of Salmonella in pig herds, regular testing is necessary to enable producers, advisors and authorities to react to sudden increases in the Salmonella prevalence in single herds or at a national level.

Faecal samples from 350 farm workers on 276 dairy farms and 50 abattoir employees from seven different operations were examined for the presence of Verocytotoxin-producing Escherichia coli O157 (VTEC O157) by an O157-specific enzyme-linked fluorescent assay followed by immuno-concentration. VTEC O157 was isolated from four (1·1%) of the farm workers. A second stool sample was obtained from the positive farm workers as well as from their household contacts. VTEC O157 was isolated from the wife of one of them. The strains from the same household shared the same Verocytotoxin genes profile, phage type and pulsed-field gel electrophoresis pattern. The VTEC O157-positive subjects had neither intestinal symptoms at the moment of sampling nor a history of bloody diarrhoea or renal failure. Our study seems to confirm the hypothesis that farm residents often develop immunity to VTEC O157 infection, possibly due to recurrent exposure to less virulent strains of VTEC.

Catheter-related bloodstream infection (CRBSI) caused by coagulase-negative staphylococci (CNS) is common in haematological patients with febrile neutropenia. As the clinical signs of CRBSI are usually scarce and it is difficult to differentiate from blood culture contamination, we tried to confirm CRBSI by molecular typing of CNS isolated from paired blood cultures (one from a peripheral vein and another from the central venous catheter hub). Blood cultures were positive in 59 (36%) out of 163 patients. CNS were isolated in 24 (40%) patients; in 14 from paired blood cultures (28 isolates) and in 10 from a single blood culture. CNS from paired blood cultures were identified as Staphylococcus epidermidis. Antimicrobial susceptibility was determined and bacteria were typed by pulsed-field gel electrophoresis (PFGE) of bacterial genomic DNA. In 13 patients, the antibiotic susceptibility of isolates was identical. The PFGE patterns from paired blood cultures were identical or closely related in 10 patients, thus confirming the presence of CRBSI. In the remaining four patients they were unrelated, and suggested a mixed infection or contamination. Since CNS isolates from three patients had identical PFGE patterns, they were probably nosocomially spread amongst them.

To clarify the determinants of vaccine trial power for non-typable Haemophilus influenzae, we constructed stochastic SIS models of infection transmission in small units (e.g. day-care centres) to calculate the equilibrium distribution of the number infected. We investigated how unit size, contact rate (modelled as a function of the unit size), external force of infection and infection duration affected the statistical power for detection of vaccine effects on susceptibility or infectiousness. Given a frequency-dependent contact rate, the prevalence, proportion of infections generated internally and the power to detect vaccine effects each increased slightly with unit size. Under a density-dependent model, unit size had much stronger effects. To maximize information allowing inference from vaccine trials, contact functions should be empirically evaluated by studying units of differing size and molecular methods should be used to help distinguish internal vs. external transmission.