Multidrug-resistant Salmonella enterica subsp. enterica serotype Typhimurium DT104L was first reported in Singapore from mid-July to mid-October 2000. Salmonella strains isolated from clinical laboratories were submitted to a reference laboratory for serotyping, phage-typing and pulsed-field gel electrophoresis (PFGE) using XbaI restriction endonuclease. An epidemiological investigation was conducted to determine the source of infection and mode of transmission using a structured questionnaire. A total of 33 cases involving mainly infants and toddlers were detected in the 3-month long outbreak. The outbreak strain was of the R-type ACGSTSu, i.e. resistant to ampicillin, chloramphenicol, gentamicin, streptomycin, tetracycline and sulphonamide. PFGE showed all isolates had an indistinguishable pattern, indicating a common source of infection. Consumption of imported dried anchovy was found to be the vehicle of transmission after adjusting for all confounding variables in the case-control study using stepwise logistic regression (OR 25·6; 95% CI 3·9–167·9; P = 0·001). Imported dried seafood should be properly processed, packed, labelled, and thoroughly cooked to prevent transmission of multidrug-resistant S. Typhimurium.

In the years 1999–2000, there was an increase in the incidence of meningococcal disease in Victoria, largely caused by Neisseria meningitidis serogroup C. This change was associated with a shift in age distribution of cases, with relatively more disease appearing in the 15–29 year age group, and with 40/58 serogroup C isolates in 2000 exhibiting a new macrorestriction pattern (pattern A). Thirty-four of 52 pattern A isolates tested displayed the novel phenotype C:2a:P1.4, and were consistently porA VR type P1.7-2,4 by DNA sequencing. Nine of 10 representative pattern A isolates analysed displayed a housekeeping gene allele profile (ST-11) that is characteristic of the electrophoretic type (ET)-15 variant that has caused outbreaks in Canada, the Czech Republic and Greece. Meningococci belonging to the ST-11 complex that were isolated in Victoria prior to 1999 did not display either restriction pattern A or PorA VR type P1.7-2,4.

On 6 May 2000, a staphylococcal food poisoning outbreak occurred at a high school, affecting 10 of the 356 students who attended the breakfast. Twenty-seven Staphylococcus aureus isolates, producing enterotoxin A (SEA), SEB-, or non-SEA-E, were recovered from 7 patients, 2 food handlers and left-overs. To investigate the outbreak, we genotyped the isolates by using pulsed-field gel electrophoresis (PFGE) and three PCR-based techniques: inter-IS256 PCR typing, protein A gene (spa) typing, and coagulase gene restriction profile (CRP) analysis. Our results show that PFGE was the most discriminatory technique, whereas the three PCR-based techniques were insufficient in the discriminatory power to distinguish the S. aureus isolates from the outbreak. Based on the enterotoxin-producing types and the results of genotyping, three distinct types of strains (A1111, B2221 and N3221) were designated. Both the A1111 and B2221 strains were found in the specimens from the patients and a hand lesion of a food handler, suggesting that the source of contamination for the outbreak was most likely originated from a food handler.

We reviewed laboratory data on non-invasive pneumococcal isolates reported from all diagnostic laboratories in Scotland during the period 1988–99. Of 4491 isolates from hospitalized patients, 654 (64·7%) were from sputum, 79 (7·8%) from the nasopharynx and 278 (27·5%) from other superficial sites. The serogroups included in the 23-valent polysaccharide vaccine caused 96–9% of all non-invasive disease in all age groups. The 7-, 9-, and 11-valent conjugated vaccine serogroups were responsible for 87–94%, 85–93%, 74–81% and 75–84% of non-invasive disease respectively in age groups <2 years, [les ]5 years, [ges ]65 years and all ages. The coverage of non-susceptible penicillin and erythromycin non-invasive isolates was >99% and >95% with the 23-valent polysaccharide and 7–11-valent conjugate vaccines respectively. The eight most common serogroups were 23, 9, 6, 19, 14, 3, 15 and 11 (in descending order). The serogroups associated with antimicrobial resistance in non-invasive disease were similar to those found in invasive disease. The finding of a similar serogroup distribution in both invasive and non-invasive disease (regardless of the site of clinical isolate), is consistent with serogroups colonizing non-sterile sites and having the potential to invade. The availability of conjugated vaccines reinforces the importance of systematic surveillance to determine accurately and regularly the coverage of pneumococcal serogroups and types causing both invasive and non-invasive disease.

The objective was to describe the current epidemiology and trends in New Zealand human leptospirosis, using descriptive epidemiology of laboratory surveillance and disease notification data, 1990–8. The annual incidence of human leptospirosis in New Zealand 1990–8 was 4·4 per 100000. Incidence was highest among meat processing workers (163·5/100000), livestock farm workers (91·7), and forestry-related workers (24·1). The most commonly detected serovars were Leptospira borgpetersenii serovar (sv.) hardjo (hardjobovis) (46·1%), L. interrogans sv. pomona (24·4%) and L. borgpetersenii sv. ballum (11·9%). The annual incidence of leptospirosis declined from 5·7/100000 in 1990–2 to 2·9/100000 in 1996–8. Incidence of L. borgpetersenii sv. hardjo and L. interrogans sv. pomona infection declined, while incidence of L. borgpetersenii sv. ballum infection increased. The incidence of human leptospirosis in New Zealand remains high for a temperate developed country. Increasing L. borgpetersenii sv. ballum case numbers suggest changing transmission patterns via direct or indirect exposure to contaminated surface water. Targeted and evaluated disease control programmes should be renewed.

We investigated the prevalence and predictors of positive tuberculin skin test (TST) results among prospective Vietnamese migrants. We interviewed and medically screened 1395 Vietnamese people aged over 15 years who had applied to migrate to Australia. Approximately 44% of applicants had an induration of 10 mm or more, and 18·6% had an induration of 15 mm or more. A positive tuberculin skin test at 5 mm, 10 mm and 15 mm of induration cut-points was significantly associated with age (OR 1·01–1·02 per year) and duration of smoking (OR 1·03–1·12 per year). Smoking appears to be an important factor associated with increased susceptibility to mycobacterial infection. It is not yet clear whether the increased tuberculin reactivity associated with smoking reflects an increased risk of tuberculosis among these migrants.

We investigated which vaccination schedule gives best protection to the vaccinating population, in case there is a measles epidemic in an area with low vaccine coverage. We considered combinations of an early measles vaccination (none, at 6 months or at 9 months), a measles–mumps–rubella (MMR) vaccination around the first birthday (at either 11 or 14 months), and MMR vaccination at an older age (at either 4 or 9 years). The different estimates on measures of protection (percentage of susceptibles, number of reported cases in an epidemic year, percentage of lifetime spent susceptible) relied on a mathematical model of decline of maternal antibody levels with age, and the impact of that antibody level on seroconversion and immunity. Model parameters were estimated from a Dutch population-based serological survey on measles antibodies. Different measures of protection favoured different vaccination schedules, but dropping the age of second MMR vaccination prevents considerably more cases than an extra early measles vaccination or dropping the age of first MMR vaccination.

An immunofluorescence test for detecting parvovirus B19 IgG was developed by infecting insect cells with recombinant baculovirus expressing the capsid protein VP1. The test was used to study the prevalence of antibodies in 725 healthy children and young adults living in Santiago, Chile. In total, 248 sera were taken in 1990 and 477 in 1996. The seroprevalence was low in children less than 5 years old (3% in 1990 and 21% in 1996). It rose during school age to a prevalence around 50%, reaching 60% in young adults. No differences were found between genders. There was a statistically significant higher seroprevalence in the low socio-economic status group in 1990 samples, but this was not observed in 1996. The higher prevalence observed in children less than 5 years of age in 1996 compared with 1990 could be explained by the occurrence of intervening epidemics of parvovirus B19 infection.

Tattoos have been shown to be associated with transfusion-transmitted diseases (TTDs), particularly hepatitis B virus (HBV) and hepatitis C virus (HCV) infections. Very little is known about the association between different categories of tattoos and TTDs. In a cross-sectional study in Brazil, we studied 182 individuals with tattoos and assessed the odds of testing positive for a TTD according to tattoo type, number, design and performance conditions. Major findings were significant associations between an increasing number of tattoos and HBV infection (odds ratio (OR) of 2·04 for two tattoos and 3·48 for [ges ] 3 tattoos), having a non-professional tattoo and testing positive for at least one TTD (OR = 3·25), and having [ges ] 3 tattoos and testing positive for at least one TTD (OR = 2·98). We suggest that non-professional tattoos and number of tattoos should be assessed as potential deferral criteria in screening blood donors.

In a cross-sectional survey of 226 HIV-infected men, we examined the occurrence of diarrhoea and its relationship to drinking water consumption patterns, risk behaviours, immune status and medication use. Diarrhoea was reported by 47% of the respondents. Neither drinking boiled nor filtered water was significantly associated with diarrhoea (OR = 0·5 [0·2, 1·6], 1·2 [0·6, 2·5] respectively), whereas those that drank bottled water were at risk for diarrhoea (OR = 3·0 [1·1, 7·8]). Overall, 47% always or often used at least one water treatment. Of the 37% who were very concerned about drinking water, 62% had diarrhoea, 70% always or often used at least one water treatment. An increase in CD4 count was protective only for those with a low risk of diarrhoea associated with medication (OR = 0·6 [0·5, 0·9]). A 30% attributable risk to diarrhoea was estimated for those with high medication risk compared to those with low medication risk. The significant association between concern with drinking water and diarrhoea as well as between concern with drinking water and water treatment suggests awareness that drinking water is a potential transmission pathway for diarrhoeal disease. At the same time we found that a significant portion of diarrhoea was associated with other sources not related to drinking water such as medication usage.

Hepatitis B carriers who acquired the infection perinatally die from hepatocellular carcinoma (HCC) and cirrhosis at high rates. Published cohort studies are largely limited to males and are too small to estimate the age-specific risk of death. We therefore used routinely collected Hong Kong data to estimate the risks. Deaths were partitioned between carriers and non-carriers, then current life table calculations determined life expectancy and probability of dying from HCC or cirrhosis. HCC is the dominant cause of death for male carriers in middle adulthood with a lifetime risk of 27% for HCC compared to 4% for females. Predicted life expectancy is 72 years for male carriers, compared to 79 years for non-carriers. Female carriers have a life expectancy of 81 years and non-carriers 83 years. This model probably applies to all southern Chinese populations and emigrants with similar life history, and other populations that acquired infection early in life.

Following the Nipah virus (NV) outbreak in March 1999 in Singapore, a serological survey was undertaken to screen individuals potentially exposed to NV. Blood samples were tested for NV IgM, IgG and neutralizing antibodies. Twenty-two (1·5%) of 1469 people tested had antibodies suggesting NV infection. Although 12 of the 22 infected people (54·6%) were symptomatic, the remaining 10 (45·4%) were clinically well and had no past history of compatible pulmonary or neurological disease. Clinical and serological findings suggested three people had been infected with NV before the outbreak was recognized. All those who were infected were male abattoir workers. None of the people who had contact with horses, and no healthcare workers exposed to infected patients and their specimens had detectable antibodies. This study provides evidence that NV causes asymptomatic infection. All of the antibody positive individuals had direct contact with pigs and there was no evidence of human to human transmission.

In order to investigate the serological relationship of Dobrava hantavirus (DOBV, originating from Slovenia) and the Dobrava-like Saaremaa virus (SAAV, recently discovered in Estonia) we analysed 37 human serum samples, 24 from Estonia and 13 from the Balkans, by focus reduction neutralization test (FRNT). Most of the Estonian sera (19), including all sera from Saaremaa island (12), reacted with higher FRNT end-point titres to the local SAAV; the majority of them (15 and 11, respectively), with at least fourfold or higher titres to SAAV than to DOBV. In contrast, out of the 13 sera collected in Slovenia, Bosnia-Herzegovina and Greece, only one reacted more strongly with SAAV (with a twofold higher titre), while 10 of these sera reacted more strongly with the local DOBV (9/10 with fourfold or higher titres). These results indicate that DOBV and SAAV define unique hantavirus serotypes.

Normally, only one isolate of Listeria monocytogenes from a case of listeriosis is subjected to characterization. Here we show that two isolates from different sites of the body were not the same strain. Such a phenomenon may not have any clinical relevance, although it may confuse the epidemiologist trying to match infection source with infection target.

In order to establish the leptospira carrier rate of small animals in an urban environment, small rodents and shrews were captured in the city of Zurich, Switzerland. Kidney specimens of 190 animals were examined using a leptospira specific PCR assay. Leptospiral DNA was amplified in kidneys of 12·6% of the animals.