Enteroaggregative Escherichia coli (EAEC) is defined by the ability to produce aggregative adherence (AA) to cultured cells. We analysed 128 EAEC strains, isolated from children with and without diarrhoea, regarding the presence of 11 EAEC virulence genes. Seventy strains carried and 58 lacked the EAEC probe sequence; 17 probe positive and 31 probe negative strains showed variations in the AA pattern. All EAEC probe positive strains carried at least one EAEC marker; aspU (94.3%), irp2 (91.4%), and aggR (74.3%) were the most prevalent. Conversely, among the EAEC probe negative strains, 41.4% were devoid of any marker and astA predominated (44.8%). No significant statistical difference in the prevalence of any marker between cases and controls in both EAEC probe groups or AA variants was found. We suggest that the EAEC probe positive strains may have a higher pathogenic potential or alternatively, EAEC probe negative strains may harbour virulence factors as yet undescribed.

Streptococcus pneumoniae is the leading bacterial cause of life-threatening infections in infants. Although antibiotic resistance affects management of pneumococcal infections, few data on patterns of resistance are available for India. We examined nasopharyngeal carriage of antibiotic-resistant pneumococci in 464 South Indian infants between 2 and 6 months. Newly acquired serotypes were screened for susceptibility to cotrimoxazole, erythromycin and penicillin using disk diffusion. Cumulative prevalence of pneumococcal carriage rose from 53·9% at 2 months to 70·2% at 6 months. The prevalence of strains that were not susceptible to penicillin, co-trimoxazole and erythromycin was 3·4, 81·1 and 37·2%, respectively. Carriage of erythromycin non-susceptible strains declined significantly between ages 4 months and 6 months (44·1 vs. 10·7%). More than 87% of the isolates screened were non-susceptible to [ges ]1 antibiotic. Serogroups/types that were most frequently non-susceptible to 1 or more antibiotics were 6, 9, 14, 19 and 23. Less than 1% of the isolates were multi-drug resistant. Widespread use of antibiotics in South India has resulted in S. pneumoniae becoming non-susceptible to some commonly used antibiotics. Monitoring trends in antibiotic susceptibility and making antibiotics available only through prescription from a health care worker may slow the spread of resistant pneumococci and improve management of pneumococcal infections in South India.

As part of an interventional study to determine glycopeptide-resistant enterococci (GRE) acquisition on a three-ward haematology unit, rectal swabs were taken weekly from 293 patients recruited to the study between June 1995 and December 1996. The GRE isolates obtained from the first positive rectal swab from 120 colonized patients, the isolates from 7 patients with clinical infection and 43 isolates obtained from the ward environment were compared by pulsed-field gel electrophoresis (PFGE). Sixty-three of 120 patients were colonized by one of strains A-H, while 49 were colonized by unique strains. The first 18 weeks were associated with the highest prevalence of GRE by rectal swab, with a single strain A responsible for 52% of acquisitions on ward 2, 22% on ward 3 and 36% on ward 4. Other smaller ward associated clusters were evident. Environmental sampling of ward 2 during this time showed that all but 2 of 30 isolates were indistinguishable from strain A. As the GRE prevalence fell, rectal swab and environmental isolates became more heterogeneous, and strain A disappeared after week 55. GRE prevalence rose again in the final 15 weeks of the study, and a new predominant strain B emerged on ward 2 responsible for 50% of new acquisitions. In the seven patients with clinical infection with GRE, the clinical isolates were compared with the contemporaneous rectal swab isolate, and were found to be the same in only two cases. An analysis of five long-term carriers colonized for a median of 19 weeks (range 11–34) showed colonization with at least two and in one case six distinct strains, raising the question of how many strains may be colonizing a patient at any one time, and suggesting that multiple colonies should be analysed. These data suggest that cross-infection was an important factor in the spread of GRE when the colonization rate was high.

Invasive group A streptococcal (GAS) infections have been of increasing concern worldwide during the past 15 years. Spread of group A streptococci to contacts with resulting invasive infection has been reported in families, in residential nursing homes, and even from patients to health care workers. We report an instance of temporally related life-threatening group A streptococcal infection in a husband and 2 weeks later in his wife. This example further emphasizes the need for careful observation among family members and other close contacts of patients with invasive group A streptococcal infection. Although at present there are no universal recommendations for monitoring or for antibiotic prophylaxis of close contacts of persons with invasive GAS infection, when added to existing literature, this report suggests additional consideration is required.

The prevalence of TT virus (TTV) and GB virus-C/hepatitis G virus (GBV-C/HGV) infection and the association with raised liver function tests in 546 Taiwanese with negative HBsAg, anti-HCV and HCV RNA was elucidated. They were tested for serum alanine aminotransferase (ALT), GBV-C/HGV RNA, anti-envelope protein 2 antibody (anti-E2) and TTV DNA. Direct sequencing and phylogenetic analyses were performed on 58 isolates for TTV genotype determination. The prevalence of TTV DNA, GBV-C/HGV RNA, anti-E2 and over all GBV-C/HGV exposure was 24.9, 3.4, 8.2 and 11.1%, respectively. Using uni- and multi-variate analyses, male gender and TTV viremia were associated significantly with raised ALT values. Sixty-nine percent of TTV isolates were deduced to be TTV genotype 1 and they had significantly lower mean age than genotype non-1 isolates. In the population, raised ALT may be related to male gender and be attributable to TTV infection but not to GBV-C/HGV among individuals with no evidence of current HBV and HCV infection. TTV genotype 1 is the most prevalent genotype and associated with younger age.

We evaluated the risk factors for childhood pneumonia with particular reference to indoor air-pollution associated with solid fuel use for cooking (e.g. coal, wood, dung), using a case-control study in a children's hospital in Calcutta. Cases were 127 children aged 2–35 months of either sex admitted with pneumonia and controls were 135 children attending their immunization clinic. Solid fuel use (odds ratio = 3.97, CI = 2.00–7.88), history of asthma in the child (OR = 5.49, CI = 2.37–12.74), poor economic status indicator (OR = 4.95, CI = 2.38 to 10.28), keeping large animals (OR = 6.03, CI = 1.13–32.27) were associated with high risk of pneumonia after adjusting for confounding (logistic regression analysis). Nearly 80% of people in India use such smoke producing fuel and the population attributable risk would be very high. This finding has important health policy implications. Furthermore, history of asthma is a useful prognostic indicator for early action for prevention of severe pneumonia.

We used microbiology and pharmacy data from health-maintenance organizations to determine whether antibiotic use by a household member increases the risk of penicillin-non-susceptible pneumococcal disease. Though it has been well established that an individual's antibiotic use increases one's risk of antibiotic-resistant infection, it is unclear whether the risk is increased if a member of one's household is exposed to antibiotics. We therefore conducted a case-control study of patients enrolled in health maintenance organizations in Western Washington and Northern California. Cases were defined as individuals with penicillin-non-susceptible pneumococcal infection; controls were individuals with penicillin-susceptible pneumococcal infection. Socioeconomic variables were obtained by linking addresses with 1997 census block group data. One-hundred and thirty-four cases were compared with 798 controls. Individual antibiotic use prior to diagnosis increased the odds of penicillin non-susceptibility, with the strongest effect seen for β-lactam use within 2 months (OR 1·8, 95% CI 1·2, 2·8). When household antibiotic use by persons other than the patient were considered, at 4 months prior to diagnosis there was a trend towards an association between penicillin non-susceptibility and β-lactam antibiotic use, and a possible association in a small subgroup of patients with eye and ear isolates. However, no significant overall pattern of association was seen. We conclude that though antibiotic use of any kind within 2 months prior to diagnosis is associated with an increased risk of penicillin-non-susceptible pneumococcal disease, there is no significant overall pattern of association between household antibiotic use and penicillin-non-susceptible pneumococcal infection.

Natural immunity to Haemophilus influenzae type b (Hib) invasive disease is based on antibodies arising in response to encounters with Hib or cross-reactive (CR) bacteria. The relative importance of Hib and CR contacts is unknown. We applied a statistical model to estimate the total rate of immunizing infections of Hib and CR prior to wide-scale vaccinations in Finland and the UK. The average rates of these contacts were 0.7 and 1.2 per year per child in Finland and the UK, respectively. Using a rough estimate of 0.1 Hib acquisitions per year per child in the UK based on carriage rates, the proportion of Hib among all immunizing contacts was in the order of 10%, suggesting that CR bacteria have a major role. In general, varying frequency of CR contacts may explain some differences in the pre-vaccination incidence and age-distribution of invasive disease in different countries.

This manuscript extends our previously published work (based on data from one clinic) on the association between three drinking water-treatment modalities (boiling, filtering, and bottling) and diarrhoeal disease in HIV-positive persons by incorporating data from two additional clinics collected in the following year. We conducted a cross-sectional survey of drinking water patterns, medication usage, and episodes of diarrhoea among HIV-positive persons attending clinics associated with the San Francisco Community Consortium. We present combined results from our previously published work in one clinic (n = 226) with data from these two additional clinics (n = 458). In this combined analysis we employed logistic regression and marginal structural modelling of the data. The relative risk of diarrhoea for ‘always’ vs. ‘never’ drinking boiled water was 0.68 (95% CI 0.45–1.04) and for ‘always’ vs. ‘never’ drinking bottled water was 1.22 (95% CI 0.82–1.82). Drinking filtered water was unrelated to diarrhoea [1.03 (95% CI 0.78, 1.35) for ‘always’ vs. ‘never’ drinking filtered water]. Adjustment for confounding did not have any notable effect on the point estimates (0.61, 1.35 and 0.98 for boiled, bottled, and filtered water respectively, as defined above). The risk of diarrhoea was lower among those consuming boiled water but this finding was not statistically significant. Because of these findings, the importance of diarrhoea in immunocompromised individuals, and the limitations of cross-sectional data further prospective investigations of water consumption and diarrhoea among HIV-positive individuals are needed.

This study examines the incidence of antibiotic-associated diarrhoea (AAD) in children in the community setting. Parents of 965 children aged 4–6 years and resident in rural/semi-rural South Australia completed a questionnaire on socio-demographic factors, and a 6-week daily diary detailing symptoms of gastroenteritis, antibiotic use, respiratory illness, and contact with someone with gastroenteritis. The incidence of AAD was 32·3%, falling to 23·5% when episodes associated with a respiratory illness were excluded. Respiratory illness in the previous 3 days (OR 6·76, 95% CI 4·87, 9·38), and contact with someone with gastroenteritis in the previous 14 days (OR 1·8, 95% CI 1·48, 2·19), were both associated with gastroenteritis. After adjusting for these, only the first day of antibiotic use was associated with gastroenteritis (OR 3·8, 95% CI 1·8, 8·06). Potential confounding factors, in particular inter-current respiratory illness, need to be considered when examining AAD.

In a study of three high-risk occupational groups using Rose Bengal and complement fixation tests, the highest prevalence (7.1%) was found among dairy farm workers and owners in randomly selected dairy-cattle farms, followed by veterinary personnel (4.5%) and inhabitants in pastoralist areas (3.0%). There was no evidence for significant differences between the three populations. Among dairy farm workers, a higher risk was associated with the presence of sheep in the farm (OR = 13.2, CI = 2.2–76.7). In the pastoral area, a high risk was linked to having close contact with animals (OR = 6.32, CI = 0.88–∞), while a reduced risk was seen for contact with cattle (OR = 0.18, CI = 0–1.30). Symptoms suggestive of brucellosis were more commonly observed among the dairy farm workers, mainly found in the highlands, than among the pastoralist area inhabitants, where malaria is prevalent. The study documents not only the presence of serological and clinical evidence of human brucellosis, but also risk factors related to it in Eritrea, for the first time.

The prevalence of anti-retroviral therapy (ART) use over time and the incidence of AIDS in a cohort of HIV-seroconverting injecting drug users (IDUs) were assessed by means of a hospital-based study of IDUs with a well documented date of HIV infection. Use of ART and clinical endpoints were assessed by hospital records. Three calendar periods (before 1992, 1992–6 and 1997–2000) were defined as corresponding to modalities of ART available. Prevalence of ART usage in each calendar period, changes in medication and, hazard of AIDS in patients reaching the same duration of HIV infection at different calendar periods were analysed. In total, 132 IDUs with a median age of 23 years at seroconversion were followed up for 6.8 years (median) (range 0.2–15.7). At the end of the study, 58 patients (44%) had developed AIDS. Before the introduction of highly active anti-retroviral therapy (HAART) 12% of patients were on ART. Starting in 1997, an increasing proportion were receiving HAART with a prevalence of 39.5% by January 2000. Taking 1992–6 as the reference category the relative hazard of AIDS during 1997–2000 was 0.42 (95% CI, 0.1–1.1) (P = 0.09). A 40% penetration of HAART in a cohort of IDUs with known dates of seroconversion resulted in a 58% reduction of the hazard of AIDS.

This study characterizes possible confounders that might make cohorts vaccinated and unvaccinated against influenza and pneumococcal infection different at baseline, with the hypothesis that the two cohorts are comparable. The similarity between health and demographic data was analysed by a randomized, multivariant study addressed to 10 000 persons aged 65 years and older in Stockholm County and was carried out in the form of a postal inquiry during the period December 2000 to May 2001. The study-population response rate was 78%. Of these, 66% (5120 persons) had been given at least one influenza vaccination during the 3-year study period (1998–2000), 50% (3780) had received one pneumococcal vaccination and 78% had received both vaccines during the period. The vaccination rate was lower in the age group 65–69 years (60%), compared with elderly cohorts aged over 70 years (67–72%, P<0·001). Elderly persons living in nursing homes or institutions had higher vaccination rates than persons living in their own households (72 vs. 67%). Persons with underlying chronic diseases had higher vaccination rates (71%, P<0·001) than those without underlying chronic diseases. Vaccine recipients had fewer days in hospital, compared with non-recipients. Unvaccinated persons with myocardial disease had nine times more days in hospital than vaccinated persons with myocardial disease. Vaccination against pneumococcal infection had an additional effect with influenza vaccination in reducing hospitalization for chronic lung diseases; influenza vaccination alone did not have this effect. In conclusion, the influenza and pneumococcal-vaccine recipients were older and had significantly more chronic lung and heart conditions than the unvaccinated cohort.

Since new vaccines and anti-viral drugs for influenza have become available, collation of actual and country-specific epidemiological data is essential. Since respiratory syncytial virus (RSV) is a well known paediatric airway pathogen and some epidemiological data exist already, a comparison between influenza and RSV seems warranted. From July 1996 to June 2001 the naso-pharyngeal aspirates (NPA) of children from birth to 16 years of age, admitted to one of the two paediatric hospitals in Kiel, Germany, were investigated by a nine-valent multiplex reverse transcriptase PCR assay. NPA were investigated in 60·8% of 3469 children admitted with an acute respiratory tract infection. Community-acquired or nosocomial infections (in parentheses) due to influenza A were diagnosed in 122 (10) children, due to influenza B in 14 (2) and due to RSV in 325 (24) cases. Patients with influenza A (median 752 days) and influenza B (median 966 days) were older than patients with RSV (median 168 days). The spectrum of disease presentation was broader in influenza than in RSV. In each winter, admissions with influenza were less common than those with RSV. Influenza B only occurred in 2 of the 5 years. The cumulative, population-based incidences per 100 000 children 0–16 (0–5, >5–16) years of age were 53 (123, 22) for influenza A, 16 (30, 9) for influenza B and 165 (453, 4) for RSV. Cardiac conditions and asthma were the major risk factors for admission to hospital with influenza A (RR 9·8, 4·1) and RSV (8·5, 2·1) infections. Underlying conditions were most common in influenza B. Low gestational age doubled the risk for admission to hospital with influenza A infection, but did not show a dose–effect relationship as in RSV. The burden of influenza-positive hospitalizations was about one third that of RSV. The incidence was similar to reports from the United States. Targeting children with underlying conditions, especially cardiac conditions and asthma in the German immunization programme is appropriate, as long as no policy for vaccination of the general paediatric population exists.

The presence of Borrelia burgdorferi s.l. and of Ehrlichia phagocytophila group was sought by PCR in Ixodes ricinus collected in a protected area of central Italy. Nymphs (n = 1475, gathered in 295 pools of 5 nymphs each) and adult ticks (n = 28) were examined. B. burgdorferi s.l. was detected in 13.8% of the nymph pools; of these, 63.4% were infected by B. valaisiana, 26.8% by B. afzelii, 7.3% by B. garinii, and 2.5% by B. burgdorferi s.s. Only a single adult male tick proved to host B. afzelii. The agent of human granulocytic ehrlichiosis (HGE) was detected in 2.7% of the nymph pools. Two HGE agent-positive nymph pools were also found to be positive for B. garinii and for B. afzelii, respectively. This is the first report from central Italy of the finding of the HGE agent in ticks.

Pogosta disease (PD), an epidemic rash-arthritis occurring in late summer is caused by Sindbis virus (SINV) and is transmitted to humans by mosquitoes. Altogether 2183 PD cases were serologically confirmed 1981–96 in Finland, with an annual incidence of 2.7/100000 (18 in the most endemic area of Northern Karelia). The annual average was 136 (varying from 1 to 1282) with epidemics occurring in August–September with a 7-year interval. Studies on 6320 patients with suspected rubella (1973–89) revealed 107 PD cases. The depth of snow cover and the temperature in May–July seemed to predict the number of cases. The morbidity was highest in 45- to 65-year-old females and lowest in children. Subclinical SINV infections were 17 times more common than the clinical ones. The SINV-antibody prevalence in fertile-age females was 0.6% in 1992; the estimated seroprevalence in Finland is about 2%. Among game animals the tetraonids (black grouse and capercaillie) had the highest seroprevalence (65%) in the epidemic year of 1981.

Roughly half (54%) of the 910 young conscripts at a garrison in Finland were vaccinated with commercial influenza vaccines in autumn 1998. During the influenza outbreak in February 1999, 12 H3N2-subtype virus strains were isolated from vaccinated patients, and 11 such strains were isolated from unvaccinated patients. The isolates were related to the vaccine strain A/Sydney/5/97 and could be classified into three subgroups based on sequence variation in the HA1 gene coding for the variable domain of viral haemagglutinin (HA). A total of 6–10 amino-acid substitutions in HA1, three of these in the receptor-binding site, differentiated the field strains from the vaccine virus. In haemagglutination inhibition (HI) tests, eight strains from the study population exhibited reduced reactivity with a variety of antisera including human post-vaccination sera. Six of these strains were isolated from vaccinated and two from unvaccinated patients. The reduced reactivity did not correlate with particular amino-acid changes in HA1. We suggest that low-reactivity viruses may have an advantage over other co-circulating variants under some circumstances characterized by enhanced immunity-mediated selection and high infection pressure. Whether the frequency of these viruses increased in our vaccinated study population cannot be determined, nor can their effect on vaccine efficacy.

Estimates of the number of hospitalizations attributable to specific pathogens are required to predict the potential impact of vaccination. All hospital admissions for lower respiratory tract infection (LRI) in children <5 years in England in 1995–8 were reviewed. Most admissions (76.8%) were not associated with specific organisms. Seasonality in pathogens that cause bronchiolitis and pneumonia was used to predict the proportion of cases with unspecified aetiology attributable to different organisms using multiple linear regression. Of 12298 admissions for LRI, 17.5% were due to RSV infection. An estimated 74.8% (95% CI, 72.0–77.7%) of ‘unspecified bronchiolitis’ admissions and 16.3% (95% CI, 13.7–18.8%) of ‘unspecified pneumonia’ admissions were RSV related. The total mean annual incidence of hospital admissions attributable to RSV is 28.3/1000 children <1 year of age, and 1.3/1000 children 1–4 years old. The greater burden of RSV infection than indicated through discharge data is revealed through applying simple statistical methods.

In 1996, a seroepidemiological study was undertaken in Spain, with the main aim of estimating the population's immunity against poliomyelitis, tetanus and diphtheria. A population-based cross-sectional study was conducted, covering the population aged 2–39 years. The sample was stratified by age and rural–urban environment, and informed consent obtained to take blood specimens from subjects attending phlebotomy centres. The study included 3932 persons and the prevalence of antibodies against all three types of poliovirus exceeded 94% across all age groups. From a high of 96% in subjects under the age of 15 years, immunity against diphtheria steadily declined to a low of 32·3% in subjects aged 30–39 years. Similarly, tetanus antitoxin concentrations indicating basic protection were present in 98–99% of the under-14 years age group; thereafter, immunity declined, until reaching 54·6% in the 30–39 years age group.

In January 1999, an outbreak of viral gastroenteritis affected more than 300 people who attended a metropolitan concert hall over a 5-day period. Norwalk-like virus (NLV) was confirmed in faecal samples by reverse transcription polymerase chain reaction assay. The index case was a concert attendee who vomited in the auditorium and adjacent male toilet. Gastrointestinal illness occurred among members of 8/15 school parties who attended the following day. Children who sat on the same level of the auditorium as the index case were much more likely to be ill than those seated elsewhere (relative risk 7.1, 95% confidence interval 5.4–9.2, P<0.001). The majority of other reported cases had not been present on the evening of the vomiting incident. Disinfection procedure was poor and the disinfectant used contained no sodium hypochlorite. Transmission most likely occurred through direct contact with contaminated fomites. The outbreak has implications for disinfection procedures following vomiting incidents at public venues.