The incidence of invasive meningococcal disease (IMD) among UK university students and non-students of similar age was investigated. In addition, we sought to identify structural risk factors associated with high rates of IMD in individual universities. Cases were ascertained via Consultants in Communicable Disease Control (or equivalent officers) between September 1994 and March 1997. Data on individual universities were obtained from university accommodation officers.

University students had an increased annual rate of invasive meningococcal disease (13·2/105, 95% CI 11·2–15·2) compared with non-students of similar age in the same health districts (5·5/105, CI 4·7–6·4) and in those health districts without universities (3·7/105, CI 2·9–4·4). This trend was highly significant. Regression analysis demonstrated catered hall accommodation to be the main structural risk factor. Higher rates of disease were observed at universities providing catered hall places for >10% of their student population (15·3/105, CI 11·8–18·8) compared with those providing places for <10% of students (5·9/105, CI 4·1–7·7). The majority of IMD amongst students was caused by serogroup B organisms.

University students in the UK are at increased risk of IMD compared with non-students of a similar age. The incidence of IMD tends to be greatest at universities with a high provision of catered hall accommodation.

Potential risk factors for sporadic verocytotoxin-producing Escherichia coli (VTEC) infection in Belgium were investigated in a matched case-control study. Thirty-seven cases, 8 infected with O157 VTEC strains (all eaeA-positive), 29 with non-O157 VTEC strains (13 eaeA-positive and 16 eaeA-negative) and 69 matched controls were interviewed. In a conditional logistic regression analysis, consumption of fish appeared to be a risk factor for infection (adjusted odds ratio (OR) 3·25, P=0·04). Contact with dogs (OR 0·27, P=0·04) and consumption of shellfish (OR 0·19, P=0·05) showed a negative association, corresponding to a decrease in risk. These findings might be explained if low level environmental exposure to VTEC induces protective immunity. Eating raw meat, a frequent habit in Belgium, or hamburgers, or eating in a fast-food restaurant was not more frequently reported by cases than controls. The exposures causing sporadic infections with VTEC, in particular non-O157 strains, may be very different from those which led to outbreaks, and may account for more cases overall.

Three molecular typing methods, pulsed-field gel electrophoresis (PFGE), ribotyping, and flagellin (flaA) gene typing, were used to discriminate within a group of 28 Campylobacter jejuni, heat-stable serotype 55 (HS55) isolates derived from cases of campylobacter enteritis occurring throughout Scotland, including 9 isolates associated with an outbreak. PFGE was found to be most discriminatory, identifying 6 distinct profiles, followed by ribotyping (5 profiles), and then flagellin gene typing (4 profiles). The coincidence of all three genotypic markers identified a dominant clonal line within the HS55 group, accounting for each of the outbreak strains, and for 9 of the 19 sporadic strains. A second, closely related, clonal line accounted for a further 5 of the sporadic strains, and also included the HS55 reference strain. Identification and monitoring of such clonal lines should facilitate more effective future epidemiological surveillance of C. jejuni.

During July 1995, an outbreak of Salmonella typhimurium definitive type (DT) 170, an unusual strain, occurred in South Wales. A case-control study found that illness was associated with eating kebabs (odds ratio undefined, P=0·002), doner kebabs (odds ratio 7·9, 95% confidence interval 1·5–20·5, P=0·02) and kebabs with yoghurt based relish (odds ratio undefined, P=0·009) but not with eating kebabs with mayonnaise-based relish (odds ratio 2·4, 95% confidence interval 0·4–13·9, P=0·53). Environmental investigations discovered a complex web of producers and wholesale suppliers. Kebab meat and yoghurt had been supplied to the two main implicated outlets by a single wholesaler. Samples of raw minced lamb and several environmental swabs taken at the wholesaler were positive for S. typhimurium DT170. Blood- stained, unsealed yoghurt pots were observed to be stored under a rack of raw lamb. Investigators of food poisoning outbreaks linked to takeaway food should consider cross- contaminated relishes and dressings as well as undercooked meat as potential vehicles of infection.

Laboratory-based surveillance of salmonella isolates serotyped at four state health departments (Illinois, Michigan, Minnesota and Wisconsin) led to the identification of multistate outbreaks of salmonella infections during 1990 (176 cases of S. javiana) and 1993 (100 cases of S. montevideo). Community-based case-control studies and product traceback implicated consumption of tomatoes from a single South Carolina tomato packer (Packer A) MOR 16·0; 95% CI 2·1, 120·6; P<0·0001 in 1990 and again in 1993 (MOR 5·7; 95% CI 1·5, 21·9; P=0·01) as the likely vehicle. Contamination likely occurred at the packing shed, where field grown tomatoes were dumped into a common water bath. These outbreaks represent part of a growing trend of large geographically dispersed outbreaks caused by sporadic or low-level contamination of widely distributed food items. Controlling contamination of agricultural commodities that are also ready-to-eat foods, particularly fruits and vegetables, presents a major challenge to industry, regulators and public health officials.

Certain fimbriae and the flagellae of Salmonella enterica serovar Typhimurium have been shown to contribute to attachment and invasion of gut epithelium in the murine typhoid infection model and to contribute to pathogenesis in the chick. However, little is known of the role these organelles play in Enteritidis poultry infections and, to study this, day-old chicks were dosed orally in separate experiments with defined multiply afimbriate and/or aflagellate mutant strains of Enteritidis. The colonization and invasion characteristics of each mutant were compared with those of the isogenic wild type strain by the determination of the number of bacteria recovered from livers and spleens at known time points post infection. Compared with wild type Enteritidis, a mutant unable to express flagella but retaining the genetic potential to express fimbriae was recovered post mortem from livers and spleens in significantly reduced numbers compared to the isogenic wild-type at all time points post infection (P<0·001). Conversely, a flagellate but multiply afimbriate mutant (defective for the elaboration of five different fimbrial types) and a flagellate but non-motile ‘paralysed’ mutant were recovered from livers and spleens in similar numbers to the wild-type. The data suggested that Enteritidis flagella, but not fimbriae, played an important role in pathogenesis in the chick model and that the flagellar apparatus itself and not motility per se contributed significantly to this role.

A pilot study to determine the microbiological quality of unpasteurized milk from goats and ewes sampled from farm shops, health food shops, and other retail premises found that 47%, (47/100) of goats' and 50% (13/26) of ewes' milk samples failed the standards prescribed by the Dairy Products (Hygiene) Regulations 1995. In addition, Staphylococcus aureus, haemolytic streptococci or enterococci, were present in excess of 102 c.f.u./ml in 9 (7%) 2 (2%) and 19 (15%) samples, respectively. Salmonella, campylobacter, verocytotoxin-producing Escherichia coli O157[ratio ]H7 and Listeria monocytogenes were not detected in the samples. At the time of purchase approximately half of the milk samples (58%) were frozen, the rest were liquid. Farm outlets sold predominantly liquid milk, other retail premises sold a frozen product. The microbiological quality of goats' and ewes' milk, whether frozen or liquid, was not significantly different. Milk sold from farm shops was of lower quality than that from health food shops and other retail premises. In this pilot study most producers (92%) supplied, and most retailers (76%) sold unpasteurized goats' and ewes' milk that contained unacceptable levels of indicator organisms. The study was carried out during the winter when goats' milk production is reduced. The results indicate the need for a full representative study of unpasteurized goats' and ewes' milk on retail sale throughout the year.

Lack of reliable data about street vendors, who are difficult to survey, has hampered efforts to improve the safety of street-vended food. A two-phase method for sampling vendors, surveying first in areas of concentrated vending activity identified by local authorities and second in randomly selected areas, was developed and implemented in two Guatemalan cities where street-vended food had been implicated in cholera transmission. In a 4-day survey in Escuintla, 59 vendors (42 from phase 1, 17 from phase 2) were interviewed. They demonstrated good knowledge of food safety and cholera but unsafe practices, implying that more effective, practical training was needed. In a 6-day survey in Guatemala City, 78 vendors (77 from phase 1, 1 from phase 2) were interviewed. Sixty-eight (87%) vendors stored water, usually in wide-mouthed vessels prone to contamination; this led to a field test of a new system for safe water storage. Useful information for public health planning and intervention can be gathered rapidly with this new method for surveying street vendors.

Pulsed field gel electrophoresis (PFGE) of the genomic DNA of Moraxella catarrhalis was done in 172 strains isolated from sputum of patients with respiratory infections in Nagasaki (130 strains), Europe (14 strains), Thailand (6 strains), Uganda (3 strains), Bangladesh (5 strains) and Kuwait (14 strains). Restriction endonuclease with SmaI generated 4–16 DNA fragments ranging from 1000 kb to 24·25 kb and was classified into 31 major groups. It was found that there were wide variations of DNA restriction patterns of strains isolated from the same and different geographical areas. DNA restriction patterns of strains isolated in Nagasaki during the last 12 years showed dynamic changes of the predominant strains in each time period. We conclude from this study that PFGE is a suitable method to document interstrain variation in M. catarrhalis.

The Andaman islands were known to be endemic for leptospirosis during the early part of the century. Later, for about six decades no information about the status of the disease in these islands was available. In the late 1980s leptospirosis reappeared among the settler population and several outbreaks have been reported with high case fatality rates. Besides settlers, these islands are the home of six primitive tribes of which two are still hostile. These tribes have ample exposure to environment conducive for transmission of leptospirosis. Since no information about the level of endemicity of the disease among the tribes is available, a seroprevalence study was carried out among all the accessible tribes of the islands. A total of 1557 serum samples from four of the tribes were collected and examined for presence of antileptospiral antibodies using Microscopic Agglutination Test (MAT) employing 10 serogroups as antigens. An overall seropositivity rate of 19·1% was observed with the highest rate of 53·5% among the Shompens. The seropositivity rates in the other tribes were 16·4% among Nicobarese, 22·2% among the Onges and 14·8% among the Great Andamanese. All of the tribes except the Onges showed a similar pattern of change in the seroprevalence rates with age. The prevalence rates were rising from low values among children to reach a peak in those aged 21–40 years and then declined. Among Onges the seroprevalence rates continued to rise beyond 40 years. In all the tribes, seroprevalence rates were found to be significantly higher among the males. The commonest serogroups encountered were Australis followed by Grippotyphosa, Icterohaemorrhagiae, Pomona and Canicola.

The prevalence of antibodies against Lyme disease spirochaetes in serum samples from 80 forestry workers at high occupational risk of Lyme disease was surveyed by enzyme-linked immunosorbent assay (ELISA) with the OspC-I synthetic peptide. The peptide is part of the outer surface protein C (OspC) amino acid sequence located in the region conserved among Borrelia burgdorferi sensu stricto or sensu lato. Positivity for antibodies against OspC-I was observed in 25 (31·3%) of the forestry workers. Of these positive cases, 12 (15·0%) and 19 (23·8%) were positive for immunoglobulin M (IgM) and IgG antibody, respectively. Among 62 workers who were negative for IgG antibody against B. garinii or B. japonica in our previous study, 9 (14·5%) and 4 (6·5%) were positive for IgM and IgG antibody, respectively, in OspC-I ELISA. These results demonstrate for the first time that Lyme disease in forestry workers can be revealed using OspC-I ELISA. We conclude that forestry workers who show positive results for antibodies against OspC-I have very likely been exposed to Lyme disease spirochaetes, and that those who show positivity for IgM antibody against OspC-I may be in the early stage of Lyme disease.

Mycobacterium avium complex (MAC) is ubiquitous throughout the world. It is an opportunistic pathogen in AIDS patients but the number of cases in HIV negative patients is also increasing. The aim of this study was to determine whether patients were being infected with different MAC strains or whether one strain was dominant. DNA obtained from isolates in Brazil and England were compared using pulsed field gel electrophoresis (PFGE). Strains from 22 Brazilian patients clustered into 7 groups but 68/90 patients had a unique strain. In all patients, Brazilian and English, the same strain was isolated repeatedly over time, some over several years. This study shows that it is most likely that Man is infected from the environment and that one strain can survive without change for many years both in the environment and in Man.

From September 1991–January 1992, there was a measles epidemic in an established refugee camp for 7000 Vietnamese ‘Boat People’ living in Hong Kong. This 16 week outbreak occurred against a backdrop of poor uptake of measles vaccination and overcrowded living conditions. Two hundred and sixty-two children were affected (155 boys, 107 girls); 235 children (89·7%) were <2 years old, age range 5–39 months. Children age 6–11 months had the highest crude attack rate (AR) of 54·3%. The highest age specific crude AR was 83·8% in children aged 14 months. Measles complications affected 234 (89·3%) children. Sixty-six children (25·2%) were admitted to hospital. There were two deaths from pneumonia, giving a case fatality rate of 0·76%. Measles control in refugee camps continues to be a public health challenge.

Haemorrhagic fever with renal syndrome (HFRS) is a human disease characterized by flu-like symptoms, renal dysfunction, and in severe cases, haemorrhagic manifestations. The causative agents of HFRS are Hantaan (HTN), Seoul (SEO), Puumala (PUU) and Dobrava (DOB) hantaviruses. Hantavirus infections are of increasing importance in Europe. Outbreaks occur in Belgium with a 3- to 4-year interval with an increasing number of cases. We describe the largest outbreak so far in Belgium with 217 serologically and clinically confirmed cases in the period between October 1995 and December 1996. We demonstrated that the use of viral antigen derived from a local PUU-strain was able to detect significantly more sera positive for IgM in an immunofluorescence assay. Furthermore, although in some cases SEO, HTN and DOB antibody-reactivities were detected by ELISA, only PUU infections could be confirmed by neutralization test. The presence of an unknown hantavirus serotype circulating in Belgium should be considered.

It is generally accepted that the reservoir hosts of cowpox virus are wild rodents, although direct evidence for this is lacking for much of the virus's geographic range. Here, through a combination of serology and PCR, we demonstrate conclusively that the main hosts in Great Britain are bank voles, wood mice and short-tailed field voles. However, we also suggest that wood mice may not be able to maintain infection alone, explaining the absence of cowpox from Ireland where voles are generally not found. Infection in wild rodents varies seasonally, and this variation probably underlies the marked seasonal incidence of infection in accidental hosts such as humans and domestic cats.

A study was conducted to characterize the risk of Plasmodium vivax infection in the Lacandon forest, southern Mexico. Blood samples and questionnaire data were collected in 1992. Malaria cases (n = 137) were identified by the presence of symptoms and a positive thick blood smear. The control group included individuals with negative antibody titres and no history of malaria (n = 4994). From 7628 individuals studied, 1006 had anti-P. vivax antibodies. Seroprevalence increased with age. Risk factors associated with infection included: place of birth outside the village of residence (odds ratio, OR 11·67; 95% CI 5·21–26·11); no use of medical services (OR 4·69, 95% CI 3·01–7·29), never using bed-nets (OR 3·98, 95% CI 1·23–12·86) and poor knowledge of malaria transmission, prevention and treatment (OR 2·30, 95% CI 1·30–4·07). Health education represents the best recommendation for controlling the disease in the area.

Anecdotal evidence suggests that the prevalence of both scabies and head lice is increasing and also that both conditions are becoming refractory to pesticide treatment. Using information obtained from the Office of National Statistics, Royal College of General Practitioners Weekly Returns Service, Department of Health, local surveys of school children from Bristol and drug sales of insecticides, we have confirmed that there has been a rise in the prevalence of both conditions. We have shown that scabies is significantly more prevalent in urbanized areas (P<0·00001), north of the country (P<0·000001), in children and women (P<0·000001) and commoner in the winter compared to the summer. Scabies was also shown to have a cyclical rise in incidence roughly every 20 years. Head lice were shown to be significantly more prevalent in children and mothers (P<0·000001) though both conditions were seen in all age groups. Head lice were also less common during the summer. Host behaviour patterns, asymptomatic carriage, drug resistance and tourism from countries or districts with a higher incidence may be important factors in the currently high prevalence of both scabies and head lice.

Escherichia coli O157 (n = 376) from 41 cattle farms were subtyped using pulsed field gel electrophoresis of endonuclease cleaved chromosomal DNA. Cleavage with XbaI resulted in 81 subtypes. Fifty-one isolates from subtypes found in more than one herd, or in herds on multiple sample collection dates were compared using the endonuclease NotI, resulting in 23 additional subtypes. Up to 11 XbaI subtypes were found per farm with up to 7 subtypes/farm identified from a single date. Indistinguishable subtypes (both XbaI and NotI) were found to persist on 4 farms for 6–24 months. Five subtypes were found on more than one farm separated by up to 640 km. Dairy farms where cattle had moved onto the farm had a similar number of subtypes as farms with no movement of cattle, and feedlots had more subtypes than dairy farms. These data indicate that there is a mechanism for multiple herd exposure to specific subtypes, there are multiple sources of exposure for cattle on farms, and on-farm reservoirs other than cattle may exist.

The objective of this study was to determine the most efficient means of sampling faeces of finisher pigs for accurate and precise farm-level estimates of antimicrobial resistance among faecal Escherichia coli. Resistance to tetracycline and gentamicin of 8250 isolates of E. coli from 55 finisher pigs on one farm was measured with a hydrophobic grid membrane filter method. The between-pig, within-pen component of variance in resistance was large (97·5%), while between-pen, within-room and between-room components were small (2·5% and 0%, respectively). Using these resistance data, the abilities of two sampling strategies to estimate prevalence were modelled with a Monte Carlo ‘bootstrap’ procedure. Compositing faecal samples from several pigs before testing produced unbiased and precise estimates of prevalence and is simpler technically than individual animal testing.

Salmonella enterica serovar Infantis is endemic in Finnish cattle. Feed contaminated with S. Infantis was distributed to cattle farms in May 1995. Following increased sampling, S. Infantis was detected on 242 farms in 1995. Molecular typing was used to differentiate the farms that were infected by the feed-related Infantis from those infected by other endemic strains. Twenty-three isolates from feed in 1995 and 413 from cattle (72 from 1992–4, 324 from 1995, 17 from 1996–7) were analysed. The feed-related Infantis was clonally related to the endemic infection by the ribotype, IS200-type and XbaI-profile. The feed isolates had a distinctive plasmid that appeared in pulsed-field gel electrophoresis as a 60 kb band when cleaved with XbaI or linearized by S1-nuclease. This plasmid appeared in cattle only since the outbreak and seemed stable on the follow-up farms. In addition to contact farms, the feedborne strain was found on 19% of the farms infected with S. Infantis in 1995 but not having bought suspected feedstuffs, possibly as secondary infections.