Seventy clinical strains of Vibrio cholerae O1 isolated from 1982–96 in Samutsakorn, a port city 30 km southwest of Bangkok where cholera occurs at low levels with regular seasonality, were characterized to investigate if there were any differences among the O1 strains isolated before, during and after the O139 epidemic. Pulsed-field gel electrophoresis (PFGE) typing, ribotyping and southern blot hybridization with a cholera toxin probe (CT genotyping) demonstrated several genotypes among O1 strains isolated before the emergence of V. cholerae O139. However, O1 strains isolated during and after the advent of O139 showed identical ribotypes which were distinctly different from the types identified in strains isolated before the emergence of O139. Ribotypes identified in strains during and after the advent of O139 were also demonstrated by O1 strains isolated immediately before the emergence of O139. Considering the seasonality of cholera in Samutsakorn, the identical ribotype and CT genotype and the closely related PFGE types shown by all O1 strains isolated during and after the appearance of O139 is remarkable and suggest that the V. cholerae O1 strain may reemerge from an environmental source. A subgroup of V. cholerae O1 strains isolated before the emergence of the O139 epidemic had a ribotype identical to a type demonstrated by O139 strains isolated in Thailand. Our results support similar findings in Bangladesh and India that a distinct O1 strain appeared during the O139 epidemic. However, compared with the apparent identical strain which replaced O139 in Bangladesh and India, the emerged O1 strain in Samutsakorn showed a different ribotype and CT genotype.

Very few Pacific islands escaped the 1918–1919 influenza pandemic. Subsequent influenza epidemics in the established colonial outposts of American Samoa and New Caledonia infected many but killed very few persons whereas the extraordinarily isolated Niue, Rotuma, Jaliut and Yule islands experienced high mortality influenza epidemics (>3% of population) following 1918. These dichotomous outcomes indicate that previous influenza exposure and degree of epidemiological isolation were important mortality risk factors during influenza epidemics on Pacific islands.

The role that animals play in the transmission of Schistosoma japonicum to humans in the Philippines remains uncertain and prior studies have not included several species, adjustment for misclassification error and clustering, or used a cohort design. A cohort study of 2468 people providing stool samples at 12 months following praziquantel treatment in 50 villages of Western Samar, the Philippines, was conducted. Stool samples from dogs, cats, rats, and water buffaloes were collected at baseline (2003–2004) and follow-up (2005). Latent-class hierarchical Bayesian log-binomial models adjusting for misclassification errors in diagnostic tests were used. The village-level baseline and follow-up prevalences of cat, dog, and rat S. japonicum infection were associated with the 12-month cumulative incidence of human S. japonicum infection, with similar magnitude and precision of effect, but correlation between infection levels made it difficult to divide their respective effects. The cumulative incidence ratios associated with a 1% increase in the prevalence of infection in dogs at baseline and in rats at follow-up were 1·04 [95% Bayesian credible interval (BCI) 1·02–1·07] and 1·02 (95% BCI 1·01–1·04), respectively, when both species were entered in the model. Dogs appear to play a role in human schistosomiasis infection while rats could be used as schistosomiasis sentinels.

The study investigated the transfer and the stability of the S. intermedius flora in three bitches and their puppies. A total of 240 cutaneous and mucosal isolates of S. intermedius was collected from three healthy Cavalier King Charles spaniels and their puppies during the immediate prepartum period and after whelping, over a total of 15 weeks. The isolates were genotyped with random amplified polymeric DNA-polymerase chain reaction analysis (RAPD-PCR) using two primers. Seventeen different genotypes of S. intermedius were identified. One or two of the genotypes were dominant in each of the bitches and their puppies. The rest were isolated only once or twice from the bitches or their puppies. The study indicates that S. intermedius flora within each studied bitch mainly consisted of one or two dominating and persistent clones, which were transferred from the dam to her puppies immediately after birth.

We report a large foodborne outbreak due to group A streptococci (GAS), which caused acute tonsillo-pharyngitis in 200–250 patrons of a company canteen in Copenhagen, Denmark, in June 2006. A retrospective cohort study of canteen users showed that consumption of cold pasta was associated with an increased risk of illness (attack rate 68%, risk ratio 4·1, P<0·0001). Indistinguishable GAS strains (emm89, T-type 3/13/B3264) were cultured from three cases and a cook, who had prepared the pasta. To our knowledge, pasta has previously only twice been incriminated as the source of a GAS outbreak. Only six foodborne GAS outbreaks have been reported in Europe since 1970, four of them in Sweden or Denmark. This geographical clustering suggests that foodborne GAS outbreaks are probably under-recognized elsewhere.

To explore the specificities of Escherichia coli bacteraemia in the elderly, the demographic, clinical and bacteriological characteristics and in-hospital mortality rate of ‘young’ (18–64 years, n = 395), ‘old’ (65–79 years, n = 372) and ‘very old’ (⩾80 years, n = 284) adult patients of the multicentre COLIBAFI cohort study were compared. Clinical and bacteriological risk factors for death were jointly identified by logistic regression and multivariate analysis within each group. ‘Young’ and ‘old’ patients had more comorbidities than ‘very old’ patients (comorbidity score: 1·5 ± 1·3 and 1·6 ± 1·2 vs. 1·2 ± 1·2, respectively; P < 0·001), and were more frequently nosocomially infected (22·3% and 23·8% vs. 8·8%, respectively; P < 0·001). ‘Old’ patients had the poorest prognosis (death rate: 16·4% vs.10·4% for ‘young’ and 12·0% for ‘very old’ patients, respectively; P = 0·039). Risk factors for death were age group-specific, suggesting a host–pathogen relationship evolving with age.

We investigated the distribution of serotypes and patterns of drug resistance of 206 strains of salmonella isolated in southern Italy in the years 1998–2000 from raw food of animal origin, faeces of food animals and animal feed. To improve knowledge of mobile genetic elements carrying the resistance genes, some molecular features were also investigated within isolates resistant to three or more antibiotics. A high proportion of isolates, 52.2% and 37.7%, respectively, belonging to both Typhimurium and other serotypes of animal origin, proved to be multidrug resistant. The DT104 complex specific multidrug pattern of resistance was quite infrequent among isolates other than Typhimurium, but resistances to nalidixic acid and kanamycin were more frequent within these last ones (36.9% vs. 11.4% and 56.5% vs. 2.2%, respectively). Class I integrons were detected in isolates of Typhimurium and seven different serotypes. The relevance of food animal environment as a drug resistance reservoir and animal food as a potential resistance gene vehicle between the farm and human ecological niches is confirmed by our findings.

The mosquitoes Aedes aegypti, A. triseriatus, Culex pipiens, C. quinquefasciatus, and Anopheles quadrimaculatus were all found to be efficient experimental vectors of Shope's virus-induced fibromas of cottontail rabbits, transmitting the virus during interrupted feedings as well as after long intervals from an infective meal. The reduviid bugs, Triatoma infestans, T. phyllosoma pallidipennis and Rhodnius prolixus, and the bedbug, Cimex lectularius, were also capable of transmitting fibroma by interrupted or delayed feeding.

Evidence from various types of experiments indicated that arthropod transmission is mechanical, the virus being extremely stable in the insects. Some experiments did indicate the possibility of virus proliferation. Although mosquitoes did seem to serve as ‘flying pins’ when transmitting virus by interrupted feeding, they certainly were distinctive in that they maintained their ability to transmit for very long periods of time. To transmit fibromas, arthropods actually must draw virus up between the stylets of the mouthparts; mosquitoes were unable to transmit by feeding through skin moistened with a suspension of fibroma virus or by feeding subsequent to having their mouthparts painted with a virus suspension.

While cottontail tumours at peak virus titres are always infective for suitable insects, the fibromas of adult domestic rabbits generally are not infective, even though the virus titre is equivalent. However, the tumours of suckling domestic rabbits do become infective for insects.

The serological properties of the two strains of Trichomonas foetus (strain B and strain M) isolated from uterine infections in cows in Belfast and in northern England, respectively, and two strains isolated from the caecum of pigs were in vestigated with rabbit antisera to each of the four strains by direct agglutination and by precipitation of a saline extract of the dired organisms in tubes and in gel-diffusion plates.

There was considerable cross-reaction between the four strains. By the use of predominantly polysaccharide fractions from strains B and M and the predominantly protein fraction TF 4 from stratin B, the polysaccharide complex of lines could be distinguished from the protein lines.

The major protein antigens were common to all four strains, but the major polysaccharide antigens were only partially shared.

The cow strains B and M were readily distinguished from each other but had a variable though slight serological relationship. The two pig strains were very closely related to each other but were not identical. Cross-reaction revealed a relation between the cow and the pig strains. The cow strain B was more closely related than the M strain to the pig strains.

The serological distinctions do not justify the separation of the pig and the cow strains of T. foetus into two species.

I wish to thank Prof. W. T. J. Morgan, F.R.S. for preparations of diethylene glycol extracts and kind advice and Dr Winifred Watkins for ethanol fractionation of antigen and for enzyme preparations. I am also grateful to Dr A. E. Pierce of the Institute of Animal Physiology at Babraham for the isolation of clones from the S2 strain.

Campylobacter organisms isolated from water samples taken weekly from ponds and land-drains in the City of Hull were compared with isolates from humans. Of 314 campylobacter organisms isolated from patients, 237 (75.5%) of the strains were identified as typical Campylobacter jejuni, whilst of 125 identified strains isolated from the water samples, 85 (68%) resembled C. jejuni in most respects but were hippurate hydrolysis negative by the Hwang and Ederer method. The ponds and land drains in the city were therefore not a source of campylobacteriosis in the people living near these water courses. The atypical C. jejuni strains isolated from the environment may be mistaken for the C. jejuni strains which cause human infection. It is therefore essential that such strains are fully identified before attributing human and animal infections to their ingestion.

The prevalence and genetic diversity of hepatitis C infection in women attending antenatal clinics in two regions of England was investigated to inform future surveillance and control measures. Women booking into antenatal care are routinely offered a test for immunity to rubella. Serum residues from these tests were unlinked, anonymized and archived as part of the Unlinked Anonymous Prevalence Monitoring Programme (UAPMP). The serum specimens were tested for anti-HCV using a cost-effective pooling strategy. After taking into account differential sampling from the UAPMP serum archive, the adjusted overall prevalence of anti-HCV was 0·43% (95% CI: 0·32–0·53) in London and 0·21% (95% CI: 0·14–0·28) in the Northern and Yorkshire region. Restriction fragment length polymorphism of amplified HCV RNA identified type 3a as the most common HCV genotype in these antenatal women. The prevalence of anti-HCV in antenatal women in the UK is low and consistent with that expected from injecting drug use.

Although human visceral leishmaniasis (VL) is a notifiable disease in Italy, there is evidence that the actual number of cases is far higher than that notified. A programme for active surveillance of VL in the 14 Italian endemic regions was launched by the Istituto Superiore di Sanità. We report data collected during a 3-year period of active surveillance in Campania, a south Tyrrhenian region covering 4·5% of the Italian territory. Out of 120 clinically suspected cases referred to medical and diagnostic references centres, there were 52 confirmed VL cases (17·3/year), i.e. 10-fold more than previously notified. Most of the infection sites were in rural areas or peripheral districts of towns in hilly parts of Naples province. An epidemic cluster of 10 cases was identified in a microfocus of Caserta province. The biochemical analysis of 23 Leishmania stocks showed a zymodeme composition indicating Campania as an old and well-established focus of VL. The data obtained emphasize that the present notification system for VL in Italy is inadequate.

This population-based cohort study aimed to investigate the incidence and relative hazard of renal and perinephric abscess (RA) in the diabetic population in Taiwan. More than a half million diabetic patients and sex- and age-matched controls were identified from the 1997 Taiwan National Health Insurance data and were linked to in-patient claims from 1997 to 2007. Person-year approach with Poisson assumption was used to estimate the incidence density (ID) of RA. The hazard ratios (HRs) of hospitalization due to RA in relation to diabetes were analysed using a Cox proportional hazard model. The ID for the diabetic and control subjects was 4·6 and 1·1/10 000 person-years, respectively, in 11 years of follow-up, representing an adjusted HR of 3·81 (95% confidence interval 3·44–4·23). This study confirmed the association of diabetes with RA, and argued that more aggressive urological care should be administered to diabetic patients.

Asymptomatic carriage of gastrointestinal zoonoses is more common in people whose profession involves them working directly with domesticated animals. Subclinical infections (defined as an infection in which symptoms are either asymptomatic or sufficiently mild to escape diagnosis) are important within a community as unknowing (asymptomatic) carriers of pathogens do not change their behaviour to prevent the spread of disease; therefore the public health significance of asymptomatic human excretion of zoonoses should not be underestimated. However, optimal strategies for managing diseases where asymptomatic carriage instigates further infection remain unresolved, and the impact on disease management is unclear. In this review we consider the environmental pathways associated with prolonged antigenic exposure and critically assess the significance of asymptomatic carriage in disease outbreaks Although screening high-risk groups for occupationally acquired diseases would be logistically problematical, there may be an economic case for identifying and treating asymptomatic carriage if the costs of screening and treatment are less than the costs of identifying and treating those individuals infected by asymptomatic hosts.

In Sweden, acute gastrointestinal illness (AGI) incidence, severity, impact on productivity, related healthcare usage and associated costs are not ascertained. We measured these in 2013–2014 using a population-based cohort reporting weekly. We defined AGI as ⩾3 episodes of loose stools or vomiting/24 h; or loose stools or vomiting with ⩾2 other gastrointestinal symptoms. After each AGI episode, we collected information about perceived severity, healthcare use and absenteeism. We calculated incidence rates, AGI absenteeism and costs comprising direct healthcare costs and productivity loss due to work/school absenteeism. A total of 3241 participants reported 1696 AGI episodes [incidence 360/1000 person-years, 95% confidence interval (CI) 326–395; highest in the <5 years age group]. In the <5 years age group, 31% of episodes were perceived as mild, 61% as moderate and 8% as severe; 9·4% led to primary-care consultations, and 1·4% to hospital admissions. In the ⩾5 years age group, 18% of episodes were perceived as mild, 64% as moderate and 18% as severe; 6·4% led to primary-care consultations, and 1·9% to hospital admissions. AGI caused 8 891 000 days of absenteeism (95% CI 6 009 000–12 780 000). AGI cost €1 005 885 000 (95% CI 754 309 000–1 257 195 000) nationally for the year. In Sweden, a minority of cases perceive AGI as a mild illness. AGI is a burden on the healthcare system and causes productivity loss, with high costs. Countries may consider these estimates when prioritizing health interventions.

Understanding the burden of respiratory pathogens on health care is key to improving public health emergency response and interventions. In temperate regions, there is a large seasonal rise in influenza and other respiratory pathogens. We have examined the associations between individual pathogens and reported respiratory tract infections to estimate attributable burden. We used multiple linear regression to model the relationship between doctor consultation data and laboratory samples from week 3 2011 until week 37 2015. We fitted separate models for consultation data with in-hours and out-of-hours doctor services, stratified by different age bands. The best fitting all ages models (R2 > 80%) for consultation data resulted in the greatest burden being associated with influenza followed by respiratory syncytial virus (RSV). For models of adult age bands, there were significant associations between consultation data and invasive Streptococcus pneumoniae. There were also smaller numbers of consultations significantly associated with rhinovirus, parainfluenza, and human metapneumovirus. We estimate that a general practice with 10 000 patients would have seen an additional 18 respiratory tract infection consultations per winter week of which six had influenza and four had RSV. Our results are important for the planning of health care services to minimise the impact of winter pressures.

• • Respiratory pathogen incidence explains over 80% of seasonal variation in respiratory consultation data.

• • Influenza and RSV are associated with the biggest seasonal rises in respiratory consultation counts.

• • A third of consultation counts associated with respiratory pathogens were due to influenza.

The preparation of purified antigen from canine hepatitis virus sources is described. This includes the manufacture of crude antigenie suspensions and their subsequent treatment to remove non-specific interfering substances.

The solubility of the antigenie substance in various solvents has been studied and its stability is briefly discussed.

The complement-fixation and precipitin tests are described in detail as they have been used for the virus studies.

Various virus-rich body tissues and fluids have been serologically tested, and the identity of antigens prepared from them as well as the antigenie similarity of the various strains of canine hepatitis virus have been established.

A regional, multistate investigation into a June–August 2013 cyclosporiasis outbreak was conducted in Nebraska, Iowa, and neighbouring states. Cases were confirmed on the basis of laboratory and clinical findings. Of 227 cases in Iowa (n = 140) and Nebraska (n = 87) residents, 162 (71%) reported dining at chain A/B restaurants – 96% reported house salad consumption. A case-control study identified chain A/B house salad as the most likely vehicle. Traceback was conducted to ascertain production lot codes of bagged salad mix (iceberg and romaine lettuce, red cabbage, and carrots) served as house salad in implicated restaurants. A single production lot code of salad mix supplied by both a common producer and distributor was linked to the majority of confirmed cases in persons reporting regional chain A/B exposure. The salad mix linked to illnesses contained imported romaine lettuce from two separate single-grower fields-of-origin and ⩾1 additional field from another grower.

Twenty-eight adult volunteers were inoculated intranasally with para influenza 2 virus and eight developed illnesses; twenty-eight volunteers were given flanks' saline and one became ill. The illnesses occurred in volunteers given between 2 × 104 and 2 × 106 TCD 50 of virus. The most prominent symptoms were sore throat, nasal stuffiness and coryza; four of the eight volunteers had sufficient coryza to be regarded as having mild colds. Although only eight volunteers had clinical evidence of infection, twenty-four had laboratory evidence of infection as judged by virus re-isolation or antibody response. Neutralization, haemagglutination-inhibition and complement-fixation tests on paired sera showed that sixteen individuals had a fourfold or greater antibody response by one or more tests including five of the eight volunteers who were ill. Twenty volunteers, including seven who were ill, had reciprocal neutralizing antibody titres of eight or more before inoculation of virus so it seems that the illnesses were due to re infection in the presence of antibody. Evidence is presented which suggests that although illnesses occurred in the presence of antibody they were due to the para influenza 2 virus and not some other agent in the inoculum. The results of these experiments seem to fulifi the third of Koch's postulates for para-influenza 2 virus as a cause of respiratory disease in adults.

We wish to thank Dr P. A. J. Tyrreil for his advice during the course of this work and in the preparation of the manuscript. We also thank Dr K. V. Shah (The Johns Hopkins University, Baltimore, U.S.A.) for help in some of the early experiments and Miss B. Ridgwell for valuable technical assistance.

The present review furnishes evidence that paratyphoid fever exhibits a good many differences from enteric fever in its epidemiological features.

The incubation period is decidedly variable and, in general, shorter than it is in enteric fever. Not only is the disease usually milder, but the case mortality figure in the present series is particularly low and one more comparable to the case mortality in Salmonella food poisoning than that of enteric fever.

It has to be recognized that acute gastro-intestinal symptoms may be present, very rarely indeed associated with all the cases but more often affecting a proportion of them, which so closely simulate acute food poisoning that that condition may be diagnosed. Usually, however, the same patients later exhibit the normal enteric picture.

The seasonal prevalence, at least as regards the onset of multiple outbreaks as distinct from isolated cases, shows a definite summer prevalence more comparable to the distribution of Salmonella food poisoning than to that of enteric fever.

The vehicles of infection are markedly different and, apart from outbreaks spread by case-to-case infection as in some institution outbreaks, almost invariably the vehicle is some form of food. Whereas milk and ice cream are common agencies in spreading both diseases water and shellfish are absent, or very rare, as vehicles in paratyphoid fever. For this disease cream takes pride of place.

I suggest that these conspicuous differences of vehicle are not associated so much with lack of opportunity to infect as with the need for a vehicle in which multiplication of the paratyphoid bacillus can occur previous to ingestion. These differences of vehicle are explainable on the assumption that the paratyphoid bacillus is less efficient at invading the human body than the typhoid bacillus, and therefore only vehicles which ensure its ingestion in considerable numbers are effective. The few water infections cited in the report bear out this contention, for in all of them water was only effective when massively infected and repeatedly consumed. This explanation is, of course, only a hypothesis, and it may be that other factors, such as preformed toxin, are also required for successful invasion.

The special implication of cream, it may be advanced, is partly due to this factor, and also that this vehicle is one which affords special opportunities for specific infection from an infective food handler.

The vehicle infectivity rate is definitely low, and in many outbreaks a surprisingly small proportion of persons at risk are attacked. The comparative infrequence of definite explosive outbreaks, even with a vehicle from which we should anticipate an outbreak to be explosive in character, is noticeable. Both these facts add support to the view that the paratyphoid bacillus does not readily infect man.

As regards the sources of infection of the vehicle I suggest that the importance of the chronic carrier has been overstressed, and that such carriers are less important in paratyphoid fever than in enteric fever. Our information is still inadequate, but the facts incline one to believe that the true chronic carrier is proportionately rarer than in enteric fever but is likely to be more associated as a causal agent with individual infections where there are opportunities for repeated infections.

On the other hand, my series of outbreaks emphasizes the fundamental importance of the transitory carrier who may be either a mild unrecognized case or a symptomless bacterially infected person. It is evident that in most outbreaks there is in addition to the recognized and so notified cases a reservoir of infected persons in one or both of these groups. Unrecognized by themselves and unknown to the Health Authority they constitute a pool of potential infection, the effectiveness of infection only limited by opportunity, and, to a minor extent, by the difficulty of the paratyphoid bacillus to establish itself as a cause of disease in the human body. No system of control can afford to neglect the potential menace of these two groups of persons.

Much more attention might profitably be given to a detailed study of the extent to which bacillary infection occurs without recognized symptoms and the extent to which these cases clear up within a reasonable period. A comprehensive investigation of isolated single cases of paratyphoid fever would, I am sure, yield valuable epidemiological results.

Influenced no doubt by the prevailing emphasis on the chronic carrier as the commonest source of infection my series shows a tendency to label any person who handled the infected vehicle and whose stools contain the paratyphoid bacillus as the source of infection of that vehicle without steps being taken to prove the contention. So frequently can the presence of the specific bacillus be equally well accounted for on the assumption that the person is a victim of infection in the actual outbreak that some attempt at proof is essential. Modern bacteriological methods are in a position to throw considerable light on the distinction between a potential cause of the outbreak and a victim of that outbreak and ought invariably to be employed.

I am impressed with the extent to which the undoubted fact that Bact. paratyphosum B is a true Salmonella influences the epidemiological picture, and I have suggested that a study of it from this angle furnishes us with a rational explanation of the main differences between its epidemiological behaviour compared with that of the typhoid bacillus.