Restriction fragment length polymorphism (RFLP) was used for the differentiation of 80 Coxiella burnetii isolates derived from animals and humans in Europe, USA, Africa and Asia. After NotI restriction of total C. burnetii DNA and pulsed field gel electrophoresis (PFGE) 20 different restriction patterns were distinguished. The index of discrimination for this typing system was 0·86. Comparison and phylogenetic analysis of the different RFLP patterns revealed evolutionary relationships among groups that corresponded to the geographical origin of the isolates. This finding was confirmed by genetic mapping. No correlation between restriction group and virulence of isolates was detected.

Since 1992, the proportion of culture-confirmed meningococcal infections compared with numbers of notified cases of meningococcal disease has decreased in England and Wales. As most meningococcal strain characterization methods depend on a clinical isolate, this has resulted in a loss of epidemiological information. To address this problem, and to aid non-culture diagnosis, a semi-nested PCR protocol for the amplification of the meningococcal porB gene from clinical specimens was developed. This gene encodes the meningococcal serotyping antigen; strain typing data was provided by hybridization of allele-specific oligonucleotide probes to the digoxigenin-labelled porB amplicon in a ‘PCR ELISA’. This assay was specific for meningococcal DNA and sensitivities of 0·81 for cerebrospinal fluid (CSF), 0·57 for serum, and 0·62 for whole blood taken from patients with proven meningococcal infection were obtained.

This paper describes 2 outbreaks of hepatitis A infection in Finland, a very low endemic area of hepatitis A infection, where a large proportion of the population is now susceptible to infection by hepatitis A virus (HAV). The first outbreak involved people attending several schools and day-care centres; the second employees of several bank branches in a different city. The initial investigation revealed that both were related to food distributed widely from separate central kitchens. Two separate case-control studies implicated imported salad food items as the most likely vehicle of infection. HAV was detected in the stool of cases from both outbreaks using reverse-transcriptase polymerase chain reaction; however, comparison of viral genome sequences proved that the viruses were of different origin and hence the outbreaks, although occurring simultaneously, were not linked. Foodborne outbreaks of HAV may represent an increasing problem in populations not immune to HAV.

The prevalence of canine and human rabies in Thailand has decreased significantly during the last decade. This has been associated with an increasing number of human post-exposure treatments. Educational efforts, mass vaccination of dogs and cats and the use of safe and effective vaccines have all made an impact. The proportion of fluorescent antibody positive dogs, among those examined for rabies averaged 54% indicating that rabies is still a major public health threat. Canine rabies vaccination is not usually performed in animals <3 months old. However, this study revealed that 14% of rabid dogs were <3 months old and 42% were [les ]6 months old. This is the age group most likely to interact with humans and other dogs. Our study also supports the World Health Organization's recommendation that observing suspected rabid dogs for 10 days is an adequate and safe practice.

Four Swedish strains of equine H3N8 influenza virus isolated from outbreaks during the last 4 years were characterized. Antigenic typing using monoclonal antibodies raised against a variety of H3N8 strains showed that the viruses are heterogeneous, the 1993 isolate being closely related to the 1991 Swedish isolate TAB/91 and the other three isolates from 1994 and 1996 being more closely related to each other. This pattern is reflected in the phylogenetic data calculated from nucleotide sequencing of the haemagglutinin genes. H3N8 equine influenza can be seen to be evolving in two distinct lineages, one European and one American. The 1993 isolate is closely related to the European lineage and is the most recent Swedish strain of this lineage to be isolated. The 1994 and 1996 isolates fit into the American lineage, which contains recent isolates from the United States and also Britain. These results indicate that American-type H3N8 viruses have become endemic in Sweden and, in light of the antigenic differences which can be observed between viruses belonging to the two lineages, we believe that equine influenza virus vaccines should be updated with an American-type virus strain.

Fourteen cases of meningococcal disease (MD) occurred in August–September 1996 in western Sydney, Australia. Seven of the 10 young adults affected had a direct or indirect link with a local nightclub. Ten of 11 systemic meningococcal isolates had the phenotype C[ratio ]2a[ratio ]P1.5 and showed close genetic relationship by pulsed-fleld gel electrophoresis (PFGE). Organisms of this phenotype have not previously caused outbreaks in Australia, but have been associated with outbreaks and hyperendemic serogroup C MD in Europe, Canada, and the United States.

This is the largest cluster of serogroup C MD reported in urban Australia, and the first involving a nightclub. The strain differentiation results were available rapidly enough to augment epidemiological investigations on a daily basis. Public health staff could thus establish links between cases quickly, follow the spread of new cases in the community, give accurate information to health officials and the press, and utilize existing knowledge about the characteristics of this phenotype to predict likely developments during the outbreak and afterwards. The strain differentiation data was also very helpful when the role of vaccination was considered, and existing guidelines on the management of outbreaks of MD could be used effectively for the first time in western Sydney.

The prevalence of sexually transmitted diseases (STD) among women visiting antenatal (ANC) and gynaecological clinics in Gondar, north-west Ethiopia, was investigated. Between April and August 1995, 728 women consented to enter the study. Prevalence rates were 5·9% (41/693) for chlamydial antigen in cervix, 18·8% (113/600) for syphilis (Treponema pallidum haemagglutination assay [TPHA]) and 25·3% (150/593) for HIV. Active syphilis (RPR)+, TPHA+ was detected in 7·4% (44/597). HIV infection rate was higher among women with higher age of first marriage and low gravidity. It was significantly associated with young age, urban residence, and presence of genital ulcer (odds ratio [OR]=6·3), and lymphadenopathy (OR=2·8) on examination. Women seropositive for syphilis had married at an earlier age, were significantly older and had changed husbands. Low gravidity and age <30 were independently significant risk factors for cervical chlamydial antigen positivity which was predominantly asymptomatic. Significant association was observed between HIV infection and syphilis (OR=2·6). Active syphilis was associated with chlamydial (OR=3·4) and HIV infection (OR=4·1). The rate of 23·4% and 15·1% of HIV seropositivity among ANC attenders and rural women respectively is an indicator of the rapid progression of the HIV epidemic in the area.

A seroepidemiologic study of herpes simplex virus type 1 (HSV-1) and 2 (HSV-2) was performed on Japanese adults. Serum samples collected between 1985–9 from a total of 536 healthy adults, female prostitutes, males with sexually transmitted diseases (STD), homosexual men, and pregnant women were studied by immunodot assays using HSV type-specific antigens, glycoproteins G (gG1 and gG2). HSV-1 infections correlated mostly with age and was widely prevalent among subjects <40 years. HSV-2 prevalence varied greatly among subgroups defined by sexual activity and was associated with risk behaviours for prostitution, infection with STD, and homosexual activity. HSV-2 seroprevalence was highest among prostitutes (80%), lowest among pregnant women (7 %), and intermediate in STD patients (23%) and homosexuals (24%). Because HSV-1 infection during childhood has been decreasing, primary genital HSV-2 infection, with its higher frequency of clinical manifestations, will become a greater burden to the public health in Japan.

A retrospective cohort study was conducted to quantitate the relationship between neutropenia and rates of clinical bacteraemia among adults with HIV infection receiving medical care at one institution between 1991–5. The primary exposure, absolute neutrophil count (ANC), was summarized as mean ANC within a given week, using a five-level stratification (reference > 1000/μl). ANC stratum-specific rates of bacteraemia were calculated, by organism type. Linear trend tests were performed to assess dose-response relationship between neutropenia and rates of bacteraemia. The cohort included 1645 patients contributing 26785 patients-weeks and 191 episodes of bacteraemia. The unadjusted effect of neutropenia was most evident for bacteraemia due to E. coli (RR 3.4), Klebsiella pneumoniae (RR 16·7), and P. aeruginosa (RR 10.4). For bacteraemia due to any of these three organisms (47 episodes), with reference ANC > 1000/μl, relative rates were: 751–1000/μl, 1·12; 501–750/μl, 2.11; 251–500/μl, 13·58; 0–250/μl, 21·89.

Variation in the genomic location and copy number of the insertion element IS1181 in methicillin-resistant Staphylococcus aureus (MRSA) was investigated. Sixty-three isolates representing the Jevons type strain (NCTC 10442), phage-propagating strains, and epidemic strains were examined. A PCR amplicon of the insertion element was used to probe genomic restriction endonuclease digests. HindIII genomic digests gave 25 distinct IS1181 patterns, while EcoRI digests gave 20 patterns. EMRSA-01, -02, -04, -06, -07, -09, -10, -11, -13 and -14 contained the element but could not be subtyped by profiling it. EMRSA-16 did not contain IS1181, consistent with a unique evolutionary origin for this major UK epidemic strain. Marked heterogeneity was observed among isolates of EMRSA-03. Each EMRSA-03 strain examined gave a unique pattern, thereby allowing subtyping of an important epidemic phage type for the purposes of hospital cross-infection control.

Parasitic infections have been reported to be relatively common among the Southeast Asian labourers in Taiwan. This study, conducted in 1992–6, was designed to determine the temporal changes of the prevalence. Faecal specimens were examined by the formalin-ethyl acetate sedimentation technique and blood samples screened using the quantitative buffy coat technique and confirmed by Giemsa stained blood smear. The overall prevalence of intestinal parasitic infections was 10·3%. The annual prevalence decreased from 33·3% in 1992–3 to 4·6% in 1995–6. The Thai (12·0%) and Indonesian (11·1%) had a higher prevalence than the Malaysian (6·7%) and Filipinos (5·9%). Opisthorchis viverrini was the most important parasite in the Thai and Trichuris trichiura in the remaining groups. Moreover, no blood parasites were found in the labourers. The dramatic temporal decline in the intestinal parasitic infections suggests that limiting the entry of infected persons, periodic follow-ups, and immediate treatment of sporadic cases are necessary in preventing transmission of non-indigenous parasites through large population change.

A survey of beef carcases in abattoirs in the UK was carried out in order to estimate the prevalence of contamination with verocytotoxin – producing Escherichia coli (VTEC) serogroup O157. Contamination with verocytotoxin-producing E. coli (VTEC) O157 was confirmed in 0·47% of the 4067 (95% confidence limits 0·22–1·00%) of neck muscle samples. A significant tendency for carcases present in the same abattoir on the same day to have similar results was found, thus suggesting cross contamination.

VTEC O157 was found in 0·83% of 6495 bovine faeces samples routinely submitted for diagnostic purposes to Veterinary Investigation Centres in England and Wales. Of the samples from cattle less than 6 months old, 3·7% of 68 samples from animals without gastrointestinal disease were positive for E. coli O157, in contrast to 0·75% of 2321 samples from cases of gastrointestinal disease. No association with season or herd type (beef or dairy) was found.

A review of empirical studies and the development of a simple theoretical framework are used to explore the relationship between Haemophilus influenzae type b (Hib) carriage and disease within populations. The models emphasize the distinction between asymptomatic and symptomatic infection. Maximum likelihood methods are used to estimate parameter values of the models and to evaluate whether models of infection and disease are satisfactory. The low incidence of carriage suggests that persistence of infection is only compatible with the absence of acquired immunity to asymptomatic infection. The slight decline in carriage rates amongst adults is compatible with acquired immunity, but could be a consequence of reduced contacts. The low rate of disease observed in adulthood cannot be explained if protection from disease is a product of previous detectable exposure to Hib alone. We estimate an Ro of 3·3 for Hib in developed countries, which suggests that current immunization programmes may eliminate the infection. Analysis of the disease data set suggests the absence of maternal immunity and increased susceptibility to disease in the oldest age classes.

The study objective was to investigate prevalence and determinants of current Helicobacter pylori infection in an asymptomatic population of middle-aged to elderly people. A cross-sectional study was conducted among 337 participants of a general education programme of the University of Ulm aged 50–85 years. Prevalence of infection as determined by means of the [13C]urea breath test was 34·8% (95% CI 29·6–40·3%) ; overall, 33·8% (95% CI 23·0–46·0) in the age group 50–59 years, 32·4% (95% CI 25·4–39·9) in the age group 60–69 years and 41·0% (95% CI 30·0–52·7) in the age group 70–85 years. Duration of school education of the father, sharing a bed with parents or siblings during childhood, and the area in which participants had grown up were independent determinants of current infection status in a multivariable analysis. We conclude that the prevalence of current H. pylori infection in healthy elderly subjects may not be as high as seroprevalence studies have suggested. Socioeconomic characteristics of childhood living conditions appear to be important determinants of infection status even at older age.

During one year from June 1992 serum IgG antibodies to Toxoplasma gondii among 35940 pregnant women were measured in a cross-sectional study conducted in Norway. The overall prevalence was 10·9%. The lowest prevalences were detected in the north (6·7%) and in the inland counties (8·2%). A significantly higher prevalence was detected in the southern counties (13·4%) where a mild, coastal climate prevails. Women with foreign names had a higher prevalence (22·6%) than women with Norwegian names (10·0%). The high prevalence among women living in the capital city (Oslo) as compared to other cities and rural areas (13·2% vs. 10·1% and 10·2% respectively), was explained by the higher proportion of foreign women in Oslo. Prevalence significantly increased with age in women over 34 years old. This increase was only detected among women with Norwegian names. An increase in prevalence according to number of children was detected. Women without children had a prevalence of 8·8% while women with three children or more had a prevalence of 14·9%. Multivariate analyses showed that being seropositive was independently associated with county of residence, age, nationality and number of children.

During a survey of foal diarrhoea between 1991 and 1994, Clostridium perfringens was significantly associated with disease with 56% of cases infected [1]. The contribution of enterotoxigenic C. perfringens to this association, was assessed by use of the reverse passive latex agglutination test for enterotoxin (RPLA; Oxoid Unipath) and vero cell toxicity neutralized by antitoxin on stored faecal samples and sporulated faecal isolates of C. perfringens. Polymerase chain reaction (PCR1) based on the DNA sequence for the whole enterotoxin gene [2] yielded a fragment from an equine isolate of the anticipated size which, cloned into plasmid M13 phage, had a sequence essentially identical to the published sequence. Consequently, all faecal isolates were also tested by PCR1 and for a part of the enterotoxin gene (PCR2).

Significant association with diarrhoea (controls not in contact with cases) was found with positive RPLA tests on faeces (OR=13, P=0·002) and isolates (OR=4·57, P=<0·0001), vero cell toxicity of isolates (OR=1·78, P=0·026), and PCR1 (OR=nd, P=0·029) but not PCR2 or vero cell toxicity of faeces. Significant association with diarrhoea was also found for isolates negative by RPLA (OR=3·91; CI 2·05–7·57; P<0·0001) or PCR1 (OR=4·81; CI 2·84–8·20; P<0·0001). Many of the isolates from RPLA positive faeces and verotoxic isolates were PCR negative and no evidence could be found for the presence of the enterotoxin gene in a random selection of RPLA positive/PCR negative isolates by gene probe on chromosomal DNA and PCR reaction product or vero cell toxicity neutralized by specific antiserum. Failure of the vero cell toxicity on faeces to be associated with diarrhoea or for cytotoxicity of cultures and RPLA on cultures to agree with the PCRs was believed to be related to the presence of other cytotoxins, the inherent cytotoxicity of equine faeces and to the poor specificity of the commercial antiserum used in the test.

Enterotoxigenic C. perfringens could not account for the overall association of C. perfringens with foal diarrhoea because (a) cultures positive by PCR, RPLA or cytotoxicity were not significantly more common amongst isolates from cases than controls; and (b) the proportion of isolates from cases positive by PCR (PCR1 or PCR2) was too small at 9·7%.

A collection (164) of isolates of Bordetella bronchiseptica made predominantly from cats (132) but also from dogs (15), pigs (12) and other species was examined by pulsed field gel electrophoresis following macrorestriction digestion with XbaI. Each isolate was analysed twice and the patterns were entirely reproducible. The isolates fell into 17 different strains (>3 bands different) and within strains there were numerous subtypes. Feline isolates fell into 12 of the 17 strains. In general, cats housed together had similar or identical strains and subtypes of B. bronchiseptica. There was no difference in the PFGE patterns of isolates made from carrier cats and those from cats with respiratory disease. Isolates from pigs and dogs were in general similar to the feline isolates and there was no great evidence for species specificity. The PFGE pattern of feline and canine isolates were more related to whether the animals were housed together rather than whether they came from dogs or cats.

Fifteen cohorts of healthy bathers were recruited at four Lake Leman beaches between 3 July and 23 August 1996 to assess the public health importance of cercarial dermatitis in Geneva, Switzerland. Telephone follow-up interviews were carried out after 2–7 days. Overall, 153 bathers out of 555 reported probable cercarial dermatitis at follow-up. Median daily attack rate was 27·7% (2·2–57·7%). Of the cases, 11·1% noticed more than 30 skin lesions, 19·6% described severe itching, 50·3% used a drug treatment, 3·9% visited a doctor and 15% claimed they would reduce their bathing activities. History of cercarial dermatitis, time spent in the water, hour of the day, barometric pressure and maximum daily atmospheric temperature predicted disease occurrence in multivariate analysis. While a benign disease, cercarial dermatitis may have a negative impact on the local water recreation industry. The identification of risk factors for the disease may help produce better preventive recommendations for the bathers.

To test the hypothesis that chronic infection with Chlamydia pneumoniae, Helicobacter pylori or cytomegalovirus is associated with coronary heart disease risk in elderly men, a nested case-control study in a cohort investigated in 1985 and 1990 in the town of Zutphen, The Netherlands, was designed. Fifty-four cases with a first diagnosed coronary event between 1985 and 1990, and 108 age-matched control subjects free of coronary heart disease during follow up were included in the study. The overall prevalence of antibodies to cytomegalovirus was 74·7%, to H. pylori 75·9% and to C. pneumoniae 84·0%. A high level of antibodies to C. pneumoniae was associated with an increased coronary heart disease risk (OR=2·76; 95% CI=1·31–5·81). This association was stronger in cases developing both myocardial infarction and angina pectoris, than in cases developing only one of these. This association was independent of potential confounders. Antibodies to cytomegalovirus or H. pylori were not associated with coronary heart disease risk. These results support the hypothesis of a role of chronic C. pneumoniae infections in the immunopathogenesis of atherosclerosis.

Rubella infections, notified by general practitioners on the basis of a clinical diagnosis, were investigated by testing blood and saliva samples for specific IgM. Overall 52 (29%) of 178 cases with appropriately timed blood specimens were confirmed as recent rubella by IgM serology. Only 2 (3%) of 74 cases in children under 5 years were confirmed compared to 50 (48%) of 104 cases in older children and adults. The confirmation rate was lower (6 %) in those with documented vaccination history than in those without (42%). The specificity of saliva rubella IgM testing compared to testing corresponding blood samples was 99%. The overall sensitivity of saliva rubella IgM testing was 81%. This rose to 90% if results from inappropriately timed specimens and specimens taking more than 1 week to reach the laboratory were excluded. A corresponding saliva rubella IgG test was 98% sensitive and 100% specific. Of 126 rubella IgM negative cases, 25 (20%) were positive for parvovirus B19 IgM. This study confirmed that rubella surveillance based on clinical reports is not specific. It also demonstrated that saliva samples, if taken 7–42 days after onset of illness and transported rapidly to the laboratory, are a feasible alternative to blood samples for rubella surveillance.