Twenty verocytotoxigenic Escherichia coli (VTEC) O118 strains isolated between 1996 and 1998 from human patients in Germany were analysed for their serotypes, their virulence markers and their epidemiological relatedness. Three strains were typed as O118[ratio ]H12, these carried only the VT2d-Ount variant gene and were not associated with diarrhoea or haemolytic uraemic syndrome (HUS). Seventeen strains were serotyped as O118[ratio ]H16 or O118[ratio ]non-motile (NM). These carried all the genes for VT1, eae and EHEC-haemolysin. The O118[ratio ]H16/NM strains were from diarrhoea (13 cases) and HUS (2 cases). Sixteen of the patients were young infants and most infections were associated with a rural environment. Evidence for zoonotic transmission from cattle to humans was found in two cases. The epidemiological relationship between the human and bovine O118[ratio ]H16/NM isolates was indicated by homogeneous plasmid patterns and by very similar XbaI restriction patterns obtained by pulsed-field gel electrophoresis. VTEC O118[ratio ]H16/NM are emerging pathogens in Germany and should be classified as new enterohaemorrhagic E. coli (EHEC) types.

Listeria monocytogenes was isolated from critical control points in a Danish turkey processing plant, from turkey products and from cases of human listeriosis. During processing in the plant the prevalence of L. monocytogenes ranged from 25·9 to 41·4%. Cleaning and disinfection decreased the prevalence to 6·4%. Isolates of L. monocytogenes were characterized by pulsed-field gel electrophoresis (PFGE) using restriction endonuclease ApaI. Identical DNA types were obtained from turkey products and the processing line even after cleaning and disinfection. Two identical DNA types were demonstrated among isolates from turkey products and human cases of listeriosis. The prevalence of L. monocytogenes in turkey products ranged from 7·3 to 17·4% for ready-to-eat products and raw products, respectively. Since none of the 27 flocks examined before slaughter sampled positive for L. monocytogenes and the prevalence increased during processing, the potential risk from turkey meat was apparently due to factory hygiene rather than intrinsic contamination of the turkeys.

Shiga toxin (Stx)-producing Escherichia coli (STEC) strains isolated from a seagull in Japan were examined. A total of 50 faecal samples was collected on a harbour bank in Hokkaido, Japan, in July 1998. Two different STEC strains, whose serotypes were O136[ratio ]H16 and O153[ratio ]H− , were isolated from the same individual by PCR screening; both of them were confirmed by ELISA and Vero cell cytotoxicity assay to be producing active Stx2 and Stx1, respectively. They harboured large plasmids, but did not carry the haemolysin or eaeA genes of STEC O157[ratio ]H7. Based on their plasmid profiles, antibiotic resistance patterns, pulsed-field gel electrophoresis analysis (PFGE), and the stx genes sequences, the isolates were different. Phylogenic analysis of the deduced Stx amino acid sequences demonstrated that the Stx toxins of seagull-origin STEC were closely associated with those of the human-origin, but not those of other animal-origin STEC. In addition, Stx2Φ-K7 phage purified from O136 STEC resembled Stx2Φ-II from human-origin O157[ratio ]H7, and was able to convert non-toxigenic E. coli to STEC. These results suggest that birds may be one of the important carriers in terms of the distribution of STEC.

Two cases of Escherichia coli O157 infection occurred in children after visiting an inner city open farm. Subsequently faecal samples collected from animal pens and samples of composted mixed animal manure and vegetable waste were examined for E. coli O157 by enrichment culture, immunomagnetic separation and culture of magnetic beads to cefixime tellurite sorbitol MacConkey agar. Strains of E. coli O157 were characterized by hybridization with DNA probes for VT1, VT2 and eaeA, plasmid profile analysis, phage typing and pulsed field gel electrophoresis (PFGE). Verocytotoxin-producing E. coli O157 strains were isolated from faecal samples from a cow, a horse, 3 breeds of pigs, 2 breeds of sheep and 2 breeds of goats and from 2 samples of compost which had been processed for 3 months. All strains were phage type 21, hybridized with probes for VT2 and eaeA but not with one for VT1, harboured 92 and 2 kb plasmids and gave indistinguishable banding patterns with PFGE. Although only two culture-confirmed cases of infection had been identified, the farm had over 100 000 visitors per year and so it was closed as a precaution both to allow a thorough investigation and to prevent further cases. The investigation identified many factors which may have contributed to transmission of E. coli O157 infection. Most of these were readily resolved by appropriate corrective measures and as there were no further cases associated with the farm during the ensuing 4 weeks it then re-opened. These cases highlight the risk, especially to young children, of acquiring zoonotic infections during visits to open farms and emphasize the need for adequate guidance and supervision before and during such visits.

For epidemiological studies of shigatoxin-producing Escherichia coli (STEC) infections, rapid, reproducible and highly discriminative methods are required. In this study, we examined the performance of the fluorescent amplified-fragment-length polymorphism (FAFLP) technique for epidemiological fingerprinting of STEC isolates and compared it to the acknowledged fingerprinting method pulsed-field gel electrophoresis (PFGE). A total of 88 STEC isolates, including 82 of serotype O157[ratio ]H7 or O157[ratio ]H−, were subjected to fingerprinting by both PFGE and FAFLP. The isolates included sporadic and epidemiologically related strains of both animal and human origin from widespread geographical locations. The FAFLP fingerprint patterns confirmed the clonal nature of STEC O157 strains. Among the 82 O157[ratio ]H7/H− isolates belonging to 49 distinct groups of epidemiological unrelated isolates, 24 FAFLP profiles and 51 PFGE patterns were obtained. Thus, PFGE had a higher discriminatory power than FAFLP and overall correlated better to available epidemiological data. Consequently, the PFGE technique remains the method of choice in epidemiological investigations of STEC infections.

Brucellosis is known to occur in Yemen but its epidemiology has not been extensively studied. The present investigation examined risk factors for human brucellosis in Yemen using a hospital-based case-control study. A total of 235 consecutive patients with brucellosis attending the Central Health Laboratory in Sana’a, Yemen, were matched in respect of age, sex, and place of residence, rural or urban, with 234 controls selected from individuals attending the Central Health Laboratory for unrelated health problems. Clinical information on patients and controls was supplemented with occupational and socio-economic data obtained by interview of cases and controls using a standard questionnaire.

After controlling for confounding factors significant risk factors for infection related to occupation as a farmer (OR 2·5 (95% CI 1·4–4·5, P < 0·0001)), shepherd (OR 7·8 (95% CI 1·0–61, P 0·05)) or microbiologist (OR 24·5 (95% CI 2·9–204, P 0·003)); and drinking fresh milk (OR 2·0 (95% CI 1·3–4·3, P 0·001)) and laban (OR 22·7 (95% CI 1·7–4·2 P < 0·0001)). Taking other milk products and offal were not risk factors. Socio-economic and educational factors were also independent risk factors. Occupational, food and socio-economic risk factors significantly confounded one another.

Yemen shares some but not all of the risk factors of neighbouring countries. The interrelation between the various factors is complex and studying any one in isolation may give a false impression of its public health significance. Control through education of the population to minimize exposure to, and contact with, animals and their milk and milk products and to boil milk before drinking it or using it to make buttermilk, would be difficult as these would represent such fundamental changes to established patterns of behaviour of this society. Ideally there would be a campaign to control the infection by animal vaccination but the costs and logistic difficulty would be great. Presently there is a clear need for doctors in Yemen to be made aware of the frequency of this infection, the means available for clinical and laboratory diagnosis and effective treatment, while strategies to control the disease in Yemen are formulated and field tested.

The number of band differences in DNA macrorestriction profiles required to distinguish unrelated strains from an index strain varies in an outbreak with the species and restriction enzyme used. In order to define this difference for epidemiological studies of Serratia marcescens, we produced DNA fingerprints from 57 isolates of the organism using the restriction enzyme XbaI and pulsed-field gel electrophoresis (PFGE). The isolates were selected on the basis of their epidemiology, serotype and phage-typing patterns to include 28 unrelated strains and 29 representatives from 2 distinct outbreaks. One of the outbreaks was prolonged, lasting for several years. Electrophoretic profiles consisting of 20 or more clearly resolved bands were obtained for all isolates. Twenty-six of the unrelated strains had unique profiles with over 10 band differences from all other strains, while 27 of the outbreak representatives could be assigned to the appropriate outbreak with confidence. The majority of the outbreak isolates had none or 2 band differences from the index profile, although 3 isolates differed by 5–7 bands. The 2 exceptions among the unrelated strains differed by 4 bands, and 3 phage typing reactions, and were isolated from London and Berlin 3 years apart, while the 2 exceptions among the outbreak collection had clearly unique profiles with over 20 band differences from each other and the outbreak profiles. Cluster analysis using Dice coefficient and UPGMA gave cut-off values of 75–78% similarity overall for related isolates, while the closest similarity for unrelated strains was 70%. The results of this study together with those of the 6 previous reports of PFGE for S. marcescens (which used either enzymes XbaI or SpeI) confirm that this technique is of value for this species and that with XbaI at least, most epidemiologically related strains will only differ by 3–4 bands. However, on occasion up to 7 band differences can be found within an apparent outbreak, which may be suggestive of genetic drift.

Klebsiella terrigena is very rarely isolated from humans; as yet, its clinical significance is uncertain. The aim of the present study was to evaluate whether this species is able to express putative virulence factors. A total of 72 faecal (n = 50) and clinical (n = 22) K. terrigena isolates was investigated and compared with faecal and clinical strains of K. pneumoniae. Mannose-sensitive haemagglutination (MSHA) was observed less often in K. terrigena (64–74%) than in K. pneumoniae strains. In contrast, the incidence of mannose-resistant haemagglutinin indicative of type 3 pili (MR/K-HA) (77–94%), serum resistance properties (10–23%), and production of enterobactin (100%) was similar in both species. None of the K. terrigena isolates were able to synthesize aerobactin; however, the frequency of aerobactin synthesis in K. pneumoniae was also only 5%. Serotyping showed capsular types K5 and K70 to be predominant. The virulence-associated serotype K2 was common in both K. terrigena and K. pneumoniae isolates. Taken together, the present results suggest that K. terrigena and K. pneumoniae are indistinguishable with respect to the expression of virulence factors.

Quantifying the local burden of disease is an important step towards the introduction of new vaccines, such as Haemophilus influenzae type b (Hib) conjugate vaccine. We adapted a generic protocol developed by the World Health Organization for population-based surveillance of bacterial meningitis. All hospitals that admit paediatric patients with meningitis in the National District, Dominican Republic were included in the system and standard laboratory methods were used. The system identified 111 cases of confirmed bacterial meningitis. Hib was the leading cause of bacterial meningitis, followed by group B streptococcus, S. pneumoniae, and N. meningitidis. Unlike hospital-based case series, this population-based system was able to calculate incidence rates. The incidence of Hib meningitis was 13 cases per 100 000 children < 5 years old. The data from this study were used by the Ministry of Health to support the introduction of routine Hib vaccination and will be used to monitor its effectiveness.

The Department of Veterans Affairs operates a large, centrally administered health care system consisting of 173 hospitals and 4 free standing outpatient clinics nationwide with approximately 945115 hospital discharges, 24·2 million outpatient visits, and 2·86 million persons served annually over the time frame of the review. The purpose of the study was to define whether such a system could effect timely change in the incidence of tuberculosis (TB) using centralized programme planning and flexible field implementation. A retrospective review of the number of newly diagnosed cases of active TB treated at veterans health care facilities between 1 October 1990 and 30 September 1997 was determined by using a standardized annual case census.

Intervention included implementation of the most current guidelines for the prevention of transmission of TB in the community and hospital setting, including administrative and engineering controls and a change in personal protective equipment. Centrally directed programme guidance, education, and funding were provided for field use in health care facilities of widely varying size and complexity.

The numbers of total reported cases of TB decreased significantly (P < 0·001) throughout the veterans health care system (nationally and regionally), with the case rate decreasing at a rate significantly greater than that seen in the USA as a whole (P < 0·0001). TB associated with multi-drug resistance (isoniazid and rifampin) and HIV coinfection also significantly decreased over the study period. Therefore, a large, centrally administered health care system can effectively combat a re-emerging infectious disease and may also demonstrate a successful outcome greater than seen in other, perhaps less organized health care settings.

In early 1992 we identified an outbreak of cryptosporidiosis in Oregon and sought to identify and control its source. We used a series of studies to identify risk factors for illness : (i) a case-control study among employees of a long-term-care facility (LTCF); (ii) a matched case-control study of the general community; (iii) a cohort study of wedding attendees; and (iv) a cross-sectional survey of the general community. Drinking Talent water was associated with illness in the LTCF (OR = 22·7, 95% CI = 2·7–1009·0), and in the community (matched OR = 9·5, 95% CI 2·3–84·1). Drinking Talent water was associated with illness only among non-Talent residents who attended the wedding (P < 0·001) and in the community (RR = 6·5, 95% CI 3·3–12·9). The outbreak was caused by contaminated municipal water from Talent in the absence of a discernible outbreak among Talent residents, suggesting persons exposed to contaminated water may develop immunity to cryptosporidiosis.

We studied case-fatality rates (CFRs) among cases of meningococcal disease (MCD) admitted to Makkah (Saudi Arabia) hospitals during the period 1988–97. Of 483 cases, 431 (89·2%) were due to strains of serogroup A, 31 (6·4%) to serogroup W135, 16 (3·3%) to serogroup C, and 5 (1·0%) to serogroup B. Eighty-one patients died (case fatality rate (CFR)) 16·8%, 95% CI 13·5%, 20·4%). The CFR in infections due to serogroup A strains was 14·8%, and for other serogroups it was 32·7% (95% CI 20·3%, 47·1%). The CFR of MCD due to N. meningitidis serogroup A increased steadily with age (P < 0·05). Seeking first medical help at a foreign Hajj medical mission and being treated in a non-specialized hospital were associated with a higher case fatality rate.

An outbreak of gastro-enteritis occurred in La Neuveville, township with 3358 inhabitants. A retrospective cohort study of 1915 participants showed that 1607 (84%) had been ill. Campylobacter jejuni was isolated from 28 patient faecal samples, Shigella sonnei from 21 patients and small round structured viruses (SRSV) from 6 patients. More than one pathogen was identified in eight persons. The epidemic curve was characteristic of a point-source outbreak. The risk for illness was significantly higher among persons who had drank unboiled drinking water than among those who had not (1290 [80·3%] of 1607 vs. 86 [27·9%] of 308; RR = 2·87; 95% CI 2·40–3·45). Risk increased significantly with the quantity of water consumed (P < 0·00 × 10−6). An SRSV isolate from water and one human faeces had an identical DNA sequence. The outbreak was due to a pump failure producing a spill of sewage into the groundwater. We conclude that transmission was waterborne and that measures including early warning, basic hygiene and sanitation improvements controlled this epidemic.

Data relating to 3313 adenovirus isolates from patients in Greater Manchester, UK between 1982 and 1996 were analysed using χ2 tests and 95% confidence intervals. Of the 3098 isolates that were typed, 18·6% were serotype 2, 14·9% serotype 3, 12·1% serotype 1 and 10·9% serotype 41. There was evidence of a seasonal occurrence of serotype 7 (March–August), serotype 2 (January–April), serotype 4 (June–August) and subgenus F (September–November). Children less than 5 years old were the most common group of patients with adenovirus infection (61·3%) compared to 24·2% for adults and only 5·6% for school children (5–15 years). Gastric symptoms were the most common amongst infants (47·6%) followed by respiratory (27·5%) and general symptoms (12·9%). In adults, the overwhelming clinical condition was conjunctivitis (88·9%). Despite the traditional association with adenoviruses, remarkably few cases of pharyngoconjunctival fever were recorded (1·7%).

Based on the invasive pneumococcal isolates referred to reference laboratories in Scotland in 1988–99, we identified the distribution of serotypes/groups and their antimicrobial resistance patterns in order to evaluate the coverage of polysaccharide and the new pneumococcal conjugate vaccines. A total of 5659 invasive isolates were included. Of these, 5124 (90·5%) were blood isolates, 308 (5·5%) were CSF isolates, 143 (2·5%) were blood and CSF and 84 (1·5%) were other normally sterile isolates. The most prevalent 11 serotypes/groups were 14, 9, 19, 6, 23, 1, 3, 4, 7, 8 and 18, in numerical order. These accounted for 84% of total serotypes/groups.

The serotypes/groups included in the 23 and 14-valent polysaccharide vaccines accounted for 96% and 88% of all isolates. Both vaccines accounted for 98% of penicillin non-susceptible and 100% of erythromycin non-susceptible isolates. The 7, 9, and 11-valent conjugate vaccines covered 61, 68 and 80% of invasive isolates respectively. The coverage of these vaccines was substantially higher in youngest age group with 84, 86 and 93% of invasive isolates in children < 2 years included in the 7, 9 and 11-valent conjugate vaccines compared with 58, 64 and 77% in adults [ges ] 65 years of age.

The serotype/group distribution of invasive isolates in Scotland varied from year to year over the period 1993–9. The coverage of the 23-valent vaccine remained above 95% in each year but the coverage of the 7, 9 and 11-valent conjugate vaccines showed more marked fluctuation with coverage as low as 53, 60 and 75% in some years. Continued surveillance of invasive pneumococcal isolates is required to inform the development of appropriate vaccine strategies to prevent pneumococcal disease in Scotland.

In April 1997, a large city in the northeastern United States changed their drinking water treatment practices. The city, which previously provided only chlorination for their surface water sources added filtration in addition to chlorination. To assess whether Cryptosporidium infections rates declined following filtration, we tested serological responses to 15/17-kDa and 27-kDa Cryptosporidium antigens among 107 community college students 1 month before and 225 students 5 months after filtration. Results suggest that levels of Cryptosporidium infections did not decline following water filtration. However, seasonal changes in other exposures may have confounded the findings. Swimming in a lake, stream or public pool and drinking untreated water from a lake or stream predicted a more intense response to one or both markers. Residence in the city, not drinking city tap water or drinking bottled water, gender, travel or exposure to pets, young pets, diapers or a household child in day care were not found to be predictive of more or less intense serological responses for either the 15/17-kDa and 27-kDa antigen.

Penicillin-resistant Streptococcus pneumoniae (PRSP) is widespread all over the world, including countries previously free of PRSP. This study was undertaken to determine the prevalence, the common serotypes and the clonality of PRSP isolated over a period of 1 year, from various clinical samples from three major hospitals in Kuwait. Strains were identified by standard methods and their antibiotic susceptibility was determined by the agar dilution method. The clonality of the isolates was determined by repetitive extragenic palindromic sequence–polymerase chain reaction (REP–PCR) genomic profiling and pulsed field gel electrophoresis (PFGE). Serotyping was done by Quellung reaction using specific antisera. We found that 55% of the S. pneumoniae were resistant to penicillin (46% and 9% exhibited intermediate and full resistance, respectively). Nearly 41% were resistant to sulfamethoxazole-trimethoprim, 9% to cefotaxime and ceftriaxone, 15% to amoxycillin-clavulanate, 17% to cefuroxime, 77% to cefaclor, and 14% to clindamycin. The commonest serotypes among the PRSPs were 6A, 6B, 14, 19F, 23F and nontypable. PFGE and REP–PCR patterns showed a large diversity of genetic clones of the PRSP. Serotypes 6B, 14, 19F and 23F were more clonally related than the others. Our data showed that the prevalence of PRSP was high, the serotypes were diversified and different genetic clones make up the population of circulating PRSP in Kuwait.

A protracted outbreak of Norwalk-like virus (NLV)-associated gastroenteritis occurred in a large hotel in North-West England between January and May 1996. We investigated the pattern of environmental contamination with NLV in the hotel during and after the outbreak. In the ninth week, 144 environmental swabs taken from around the hotel were tested for NLV by nested RT–PCR. The sites were categorized according to the likelihood of direct contamination with vomit/faeces. The highest proportion of positive samples were detected in directly contaminated carpets, but amplicons were detected in sites above 1·5 m which are unlikely to have been contaminated directly. The trend in positivity of different sites paralleled the diminishing likelihood of direct contamination. A second environmental investigation of the same sites 5 months after the outbreak had finished were all negative by RT–PCR. This study demonstrates for the first time the extent of environmental contamination that may occur during a large NLV outbreak.

Most of the countries in western Europe have now implemented mass infant rubella immunization programmes, instead of or in addition to selective vaccination in order to achieve the elimination of congenital rubella syndrome.

The European countries Denmark, England and Wales, Finland, France, Germany, Italy and the Netherlands undertook large, national serological surveys collecting several thousand serum specimens during 1994–8. Antibodies against rubella virus were detected by a variety of enzyme immuno-assays. Comparability of the assay results was achieved by a standardized methodology. The age- and sex-stratified serological results were related to the schedules, coverage of rubella vaccination and the incidence in these countries.

The results show widely differing levels of immunity to rubella both in the general population and in the specific age groups of males and females. A low rate (< 5%) of susceptibles in childhood and adolescents of both sexes was obtained only in Finland and the Netherlands.

Countries such as Italy with only moderate coverage for the infant immunization programme currently have both high susceptibility levels in the general population and in the at-risk population. The likelihood is of continued epidemics of rubella with cases of congenital rubella syndrome. The continued implementation of selective vaccination will help to offset the impact of this ongoing transmission and to protect women on reaching childbearing age.

Carriage of Neisseria lactamica among household contacts of meningococcal disease (MCD) cases was investigated during an epidemic in Auckland, New Zealand. The overall carriage rate for N. lactamica was 10·5% (95% CI 7·4–13·5%) with a peak carriage rate in 2-year-olds of 61·5% (95% CI 26·6–88·1%). Factors associated with a significant (P < 0·05) increase in the likelihood of carriage included runny nose, the number of people per bedroom and youth. Genetic analysis of isolates revealed a striking correlation of strains within the same household but a high level of diversity between households, suggesting that household contact is an important factor in acquisition. For household contacts aged less than 5 years, there was a higher rate of carriage amongst those in contact with MCD cases under 8 years old than for contacts of cases aged 8 years and over. It is likely that development of MCD is a reflection of the nature and intensity of the exposure to a virulent strain of N. meningitidis, coupled with an absence of host resistance among those individuals not carrying N. lactamica.