During recent years a pandemic clone of Vibrio parahaemolyticus has emerged. Isolates of this clone are distributed among several serotypes, but are genotypically related. In the present study, a phenotyping method (biochemical fingerprinting) was used to characterize pandemic and non-pandemic isolates belonging to V. parahaemolyticus. It was found that the pandemic isolates showed a high level of phenotypic homogeneity and a majority of the pandemic isolates belonged to the same biochemical phenotype, whereas non-pandemic V. parahemolyticus isolates were more heterogeneous. In conclusion, biochemical fingerprinting of V. parahaemolyticus can be used as a first screening method to differentiate between pandemic and non-pandemic isolates of V. parahaemolyticus.

Studies of group A, M type 49 streptococci from England, Trinidad and Alaska indicate that isolates of this serotype often differ with respect to phage subtype from one geographical areato another, but are generally homogeneous in one place at one time. The findings support the conclusion that acute glomerulonephritis can be associated with a variety of phage subtypes of M type 49 streptococci.

In outbreaks of skin sepsis without nephritis in England, the phage subtypes of M type 49 streptococci isolated from skin lesions of meat handlers were the same as those recovered from skin lesions of non-meat handlers in the same community.

The findings on the Trinidad isolates suggest that M type 49 streptococci of one phage subtype may persist in a population for 9 years and may result in a second outbreak of acute glomerulonephritis.

In an Alaska Eskimo population in whom acute glomerulonephritis was occurring, most of the M type 49 isolates available for testing were of a single phage subtype. Equally prevalent in this population were group A streptococci that exhibited the same T antigen as the type 49 isolates but differed in their serum opacity reaction and phage subtype. This apparently related strain was not typable with available M antisera but showed functional evidence of M protein and is probably a new M type.

All the non-biting flies examined, C. erythrocephala, M. domestica, S. carnaria, F. canicularis, L. caesar and O. anthrax, possess a filtering apparatus situated in the pseudo-tracheae of the suctorial disc. The anatomy and action of this filter have been most thoroughly studied in C. erythrocephala. The suctorial disc is grooved by pseudo-tracheae which end near its centre in closed collecting channels. The latter open into furrows or gutters formed by the peculiar disposition of the prestomal teeth on the walls of the prestomal cavity. The opening of the mouth is situated at the base of the cavity. During natural feeding the lobes of the suctorial disc are pressed together so that the lumen of the prestomal cavity is obliterated, and no food can enter the mouth except through the collecting tubes. The pseudo-tracheae are channels kept open by chitinous rings situated in their walls. Each ring has one bifid extremity, enclosing between the horns the “interbifid space”, which forms an opening of definite size into the pseudo-trachea. A fold in the cuticle, the “interbifid groove”, leads to each interbifid space.

The fluid food is sucked first along the interbifid grooves through the chitin-lined interbifid spaces into the pseudo-tracheae. Particles of larger diameter than the interbifid spaces (·006 mm.) are usually prevented from entering the mouth and are rejected. The fluid and smaller particles are drawn along the pseudo-tracheae, through the collecting channels and gutters between the prestomal teeth into the mouth. By means of strong suction two opposite interbifid grooves may be made to communicate with each other owing to the lateral fissures connecting with the longitudinal pseudo-tracheal fissure being forced open, and consequently a few larger particles, up to ·02 mm. in diameter, may be drawn into the pseudo-tracheae.

Certain relatively large and very attractive objects, such as the ova of tape-worms, too large to pass through the filter, may occasionally be swallowed. Such objects probably pass directly into the mouth, when the prestomal cavity is open, during the prolonged sucking efforts made by the flies.

The large number of experiments which have been made leave little room for doubt that under natural conditions, especially when the fly is feeding on a thin film of moisture, the filtering apparatus works with a high degree of efficiency.

A suspected dengue fever outbreak occurred in 2010 at a solitary construction site in Shenzhen city, China. To investigate this epidemic, we used serological, molecular biological, and bioinformatics techniques. Of nine serum samples from suspected patients, we detected seven positive for dengue virus (DENV) antibodies, eight for DENV-1 RNA, and three containing live viruses. The isolated virus, SZ1029 strain, was sequenced and confirmed as DENV-1, showing the highest E-gene homology to D1/Malaysia/36000/05 and SG(EHI)DED142808 strains recently reported in Southeast Asia. Further phylogenetic tree analysis confirmed their close relationship. At the epidemic site, we also detected 14 asymptomatic co-workers (out of 291) positive for DENV antibody, and DENV-1-positive mosquitoes. Thus, we concluded that DENV-1 caused the first local dengue fever outbreak in Shenzhen. Because no imported case was identified, the molecular fingerprints of the SZ1029 strain suggest this outbreak may be due to vertical transmission imported from Southeast Asia.

1. Farr's 63 healthy districts are, as a whole, representative of the stationary districts of England and Wales, i.e. those districts in which growth or decline of industry has, on the whole, been absent and in which mortality rates are consequently free from the influence of industrialisation, though not necessarily unaffected by urbanisation.

2. These healthy districts maintained, until 1901–10, the advantage they held over England and Wales as regards their relative death rates in 1851–60.

3. From 1851–60 to 1901–10 the death rate of the healthy districts remained roughly constant at 76 per cent, of the death rate of England and Wales. Both improved their total death rate to the extent of 30 per cent, of what it was in 1851–60, the rates for this decennium being—England and Wales 21·17, healthy districts 16·13 per 1000.

4. The population of the healthy districts has been unfavourably constituted for a low death rate throughout the period.

5. That the periods during which the most improvement was made in lowering the death rate—not only in the healthy districts, but in England and Wales as a whole—were 1881—90 and 1901–25.

6. By 1921–5 the position of the healthy districts had become a little less favourable, their death rate having risen from 76 to 86 per cent, of that of England and Wales. It is quite possible, however, that this is due, not so much to a falling-off in the rate of improvement in the healthy districts, as to an exceptional increased improvement in backward, very unhealthy districts.

7. For the following diseases, the healthy districts show improvement at faster rates, of varying degrees, than England and Wales as a whole, during the period 1851–1925. Measles, scarlet fever, whooping cough, diphtheria, pulmonary tuberculosis, and respiratory diseases.

On the other hand, the data relating to diarrhoea seems to indicate less improvement, though inherent deficiencies in the data make this a matter open to doubt.

The death rate from cancer, which has increased considerably in the whole country during the last forty years, appears to have increased at a slightly faster rate in the healthy districts.

But, as discussed in the report, the untrustworthiness of the data, relating to comparisons of individual disease death rates over long periods of time, make it essential to regard the points enumerated in conclusion 7 rather in the manner of interesting possibilities than as proven facts.

8. When the 141 administrative areas, which in 1920–5 corresponded to Dr Farr's original healthy districts, were classified as to whether the majority of their occupied persons worked in other districts or in their own district, the standardised death rates found were as follows:

I. Districts in which 50 per cent, of occupied persons work in other districts. Death rate = 10·55 per 1000.

II. Districts in which more than 50 per cent, of occupied persons work within the district. Death rate = 9·90 per 1000.

When the second of these classes is sub-divided according to whether 50–75 per cent, or over 75 per cent, of occupied persons work within the district, the death rates are:

(a) 50–75 per cent, of occupied persons working within the district. Death rate = 9·69 per 1000.

(b) 75–100 per cent, of occupied persons working within the district. Death rate = 10·14 per 1000.

When the same class is sub-divided according to whether the majority of workers are engaged in non-agricultural or agricultural pursuits, the death rates in each sub-class are:

(a) Mainly non-agricultural. Death rate = 9·85 per 1000.

(b) Mainly agricultural. Death rate = 9·98 per 1000.

Evidence was presented to support a hypothesis that competition between antibody molecules can be an important factor in vaccinia virus neutralization.

It has been shown that there is little difference in the virus neutralizing properties of 7 S and 19 S antibody and it has been further postulated that in the context of protective immunity the proportions of antibodies having neutralizing and interfering effects is likely to be more important than the absolute concentration of neutralizing antibody or the type of immunoglobulin in which it is present.

Trials of aqueous and oil adjuvant vaccines in young adult volunteers showed that severe local reactions were rare. However, the incidence of minor symptoms was too high for a vaccine which requires to be administered repeatedly. In contradistinction to some reports, systemic and allergic reactions did not constitute a problem.

Healthy persons were shown to possess circulating antibodies of both IgA, IgG and IgM isotype directed against the bacteria of their faecal microflora, assessed by immunomorphometry. After removal, by absorption, of the fraction of antibodies directed against the autochthonous faecal bacteria or cross-reacting with allogenous faecal bacteria, there were still antibodies left directed against allogenous faecal bacteria of both the IgA, IgG and IgM isotype. However, relatively more antibodies of the IgA isotype appeared to be directed against allogenous bacteria than against indigenous faecal bacteria. Persons who reacted with specific antibodies to many bacteria of their own flora also tended to react specifically to bacteria in the allogenous microflora of the other volunteers. The patterns of antibodies directed to faecal bacteria of different morphologies (morphotypes) were unique for each individual.

The serotype distribution of 874 strains of Streptococcus pneumoniae was determined in relation to patients' age and to frequency of isolation from systemic disease. Types 14 and 18, in pre-school children, and types 1, 4, 7, 8 and 12 in patients over 5 years of age were significantly associated with systemic disease whereas type 23 in pre-school children, and type 6 in older patients was associated with upper respiratory tract carriage. No significant difference was found in the incidence of other types in systemic disease compared to upper respiratory tract carriage.

Fifteen diagnostic pneumococcal antisera (to types 1, 3, 4, 6, 7, 8, 9, 11, 12, 14, 17, 18, 19, 22 and 23) sufficed for typing 87% of strains.

Four hundred and seven clinical isolates of Escherichia coli were examined for the presence of plasmids. These isolates comprised 189 which were collected irrespective of antimicrobial resistance (VP) and 218 which were collected on the basis of high-level trimethoprim resistance (TPR). The VP isolates were divided into drug sensitive (VPS) and drug-resistant (VPR) subpopulations.

Plasmids were detected in 88% of VP isolates (81% of VPS and 94% of VPR) and 98% of TPR isolates. The distribution of plasmids in both groups and subpopulations was very similar. However, there were small but statistically significant differences between the plasmid distributions. These showed that more isolates in the resistant groups harboured plasmids than in the sensitive subpopulation (VPS) and that the number of plasmids carried by resistant isolates was greater. Multiple drug resistance was significantly more common among TPR isolates than the VPR subpopulation and this was paralleled by increased numbers of plasmids.

Fifty-eight per cent of VPR and 57% of TPR isolates transferred antimicrobial resistance and plasmids to E. coli K12. Of the R+ isolates, 60% carried small plasmids (MW < 20Md) and 52% of these co-transferred with R-plasmids. These results are discussed.

In 2009, we examined HIV and sexually transmitted infections (STIs) in 750 female sex workers (FSWs) in Shanghai using a cross-sectional survey. Participants (mean age 27 years) were interviewed and tested for HIV and selected STIs. Prevalence was: HIV 0·13%, chlamydia 14·7%, gonorrhoea 3·5% and syphilis 1·3%. In a demographic multivariate model, younger age, higher income and originating from provinces other than Zhejiang and Shanghai were independently associated with STI. In a social and sexual behavioural model, women working in small venues with fewer clients per week, use of drugs, and higher price charged per sex act indicated a greater risk for STI. Although HIV appears rare in Shanghai FSWs, chlamydial infection is common, especially in women aged <25 years (prevalence 19·6%). Since STI and HIV share similar risk factors, preventive intervention measures should be implemented immediately based on the venues and characteristics of FSWs to prevent future spread of HIV.

National health statistics report a 2·5-fold increase in laboratory-confirmed Chlamydia trachomatis (CT) cases over the last decade in Switzerland where no CT screening programme exists. We obtained essential denominator information to describe the epidemiology of CT in the canton of Basel-Stadt, an urban canton in north-western Switzerland. Laboratories reporting at least two CT infections from Basel-Stadt residents to the SFOPH in 2010 provided demographic and test-related data. CT positivity rates were calculated for 2002–2010. The influences of test year, age, sex and laboratory on CT positivity were investigated in a multivariable model. Positivity differed between sexes and age groups. In our sample of 32 034 records, female and male CT positivity rates were 4·7% and 11·1%, respectively. Test year was significantly associated with test outcome in the multivariable analysis but no time trend was observed. CT positivity did not change over the past 9 years in Basel-Stadt. In contrast to other European countries without CT screening, we found no evidence that the observed increase of Chlamydia cases in the national notification system represents an epidemiological trend, but rather results from an increased testing frequency.

This account of an outbreak of food poisoning may prove interesting, as its origin is attributed to a somewhat unusual source.

The influence of pH arid temperature on the efficiency of chlorine inactivation of two unrelated picornaviruses in a typical urban wastewater effluent was examined. Temperature, unlike pH, had relatively little effect on the rate of inactivation. The pH effect was complex and the two viruses differed. The f2 coliphage was more sensitive to chlorine at low pH, but at all values there was a threshold above which additional chlorine resulted in very rapid inactivation. The amount of chlorine required for this was less at low than at high pH, although at pH values above 7 the extent of inactivation was about the same. There was no apparent correlation between pH and rate of inactivation of poliovirus but there was a suggestion that at a pH close to the isoelectric point of the virus it was less sensitive to chlorination.

Human papillomavirus (HPV) is a DNA virus linked to mucosal and cutaneous carcinogenesis. More than 200 different HPV types exist. We carried out a transversal study to investigate the prevalence of HPV types in two regions of Mexico. A total of 724 genital and non-genital samples from women (F) and men (M) were studied; 241 (33%) from North-Eastern (NE) and 483 (66%) from South-Central (SC) Mexico. The overall prevalence was 87%. In genital lesions from females, the NE group showed a prevalence of HPV types 16 (37%), 6 (13%), 59 (6%), 11, 18 and 66 (5.4% each); and the SC group showed types 6 (17%), 16 (15%), 11 (14.5%), 18 (12%) and 53 (6%). In the genital lesions from males, NE group showed types 16 (38%), 6 (21%), 11 (13%) and 59 plus 31 (7.5%) and the SC group showed types 6 (25%), 11 (22%), 18 (17%) and 16 (11.5%). When the two regions were compared, a higher prevalence of low-risk HPV 6 and 11 was found in the SC region and of high-risk HPV 59, 31 and 66 (the latter can also be present in benign lesions) in the NE region. Our findings complement efforts to understand HPV demographics as a prerequisite to guide and assess the impact of preventive interventions.

Human innate immune plays an essential role in the spontaneous clearance of acute infection and therapy of HCV. We investigated whether the SNPs in retinoic acid-inducible gene I-like receptor family were associated with HCV spontaneous clearance and response to treatment. To evaluate the clinical value of DDX58 rs3824456, rs10813831 and rs10738889 genotypes on HCV spontaneous clearance and treatment response in Chinese Han population, we genotyped 1001 HCV persistent infectors, 599 participants with HCV natural clearance and 354 patients with PEGylated interferon-α and ribavirin (PEG IFN-α/RBV) treatment. People carrying rs10813831-G allele genotype were more liable to achieve spontaneous clearance than the carriage of the T allele (dominant model: adjusted OR 1.35, 95% CI 1.08–1.71, P = 0.008). In rs10738889, the rate of persistent infection was significantly lower in patients with the TC genotype compared to those with TT genotype (dominant model: adjusted OR 1.36, 95% CI 1.06–1.74, P = 0.015). Multivariate stepwise analysis indicated that rs10738889, age, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were independent predictors for HCV spontaneous clearance. However, there were no significant differences in the three selection SNPs between the non-SVR group and the SVR group. These results suggest the DDX58 rs10813831 and rs10738889 are associated with spontaneous clearance of HCV, which may be identified as a predictive marker in the Chinese Han population of HCV.

Oesophageal cancer is the most common gastrointestinal malignancy in China and one of the major causes of death due to cancer worldwide. The occurrence of oesophageal cancer is a multifactor, multistage, and multistep process influenced by heredity, the environment, and microorganisms. Specifically, bacterial infection may be involved in the process of tissue carcinogenesis by directly or indirectly influencing tumour occurrence and development. Porphyromonas gingivalis is an important pathogen causing periodontitis, and periodontitis can promote the occurrence of various tumours. An increasing number of studies to date have shown that P. gingivalis plays an important role in the occurrence and development of oesophageal cancer. Overall, exploring how P. gingivalis promotes oesophageal cancer occurrence and development and how it affects the prognosis of these patients is of great importance for the diagnosis, prevention, and treatment of this type of cancer. Herein, the latest progress is reviewed.

Between 21 November and 22 December 2020, a SARS-CoV-2 community testing pilot took place in the South Wales Valleys. We conducted a case-control study in adults taking part in the pilot using an anonymous online questionnaire. Social, demographic and behavioural factors were compared in people with a positive lateral flow test (cases) and a sample of negatives (controls). A total of 199 cases and 2621 controls completed a questionnaire (response rates: 27.1 and 37.6% respectively). Following adjustment, cases were more likely to work in the hospitality sector (aOR 3.39, 95% CI 1.43–8.03), social care (aOR 2.63, 1.22–5.67) or healthcare (aOR 2.31, 1.29–4.13), live with someone self-isolating due to contact with a case (aOR 3.07, 2.03–4.62), visit a pub (aOR 2.87, 1.11–7.37) and smoke or vape (aOR 1.54, 1.02–2.32). In this community, and at this point in the epidemic, reducing transmission from a household contact who is self-isolating would have the biggest public health impact (population-attributable fraction: 0.2). As restrictions on social mixing are relaxed, hospitality venues will become of greater public health importance, and those working in this sector should be adequately protected. Smoking or vaping may be an important modifiable risk factor.

The occurrence of epidemics of influenza in Britain since 1957, when the A 2 (Asian) virus was first introduced, has been traced by an analysis of influenza deaths and sickness insurance benefit claims. In a more detailed study of the epidemic in 1967–8, the largest for 7 years, mortality statistics, sickness benefit claims, consultation rates in general practice and laboratory reports were analysed according to time and geographical location, the age distribution of cases and their clinical features. The value of these various indices in the surveillance of influenza is discussed. It is estimated that the number of cases of influenza during the 1967–8 epidemic was just over one million in the working population and almost two millions in the whole population of Britain.

We wish to thank Dr D. L. Crombie, Honorary Director of the Royal College of General Practitioners' Records and Statistics Unit for permission to quote from returns compiled by the Unit and Mrs P. Jones who extracted the information; we also thank Dr A. M. Adelstein of the General Register Office and Dr J. R. Connelly and Dr A. T. Roden of the Department of Health and Social Security for their helpful comments, and the many laboratory directors whose findings are reported in the Communicable Disease Report of the PHLS. We are also much indebted to Mrs R. Narasimhan who helped with the analysis of the data.

The aim was to analyse variation in incidence of sporadic Legionnaires' disease in a geographical information system in three time periods (1990–2005) by the application of a grid model and to assess the model's validity by analysing variation according to grid position. Coordinates of the addresses at time of disease of 606 confirmed cases with Legionnaires' disease were obtained. The incidence was calculated in cells of 10×10 km in 25 different grids superimposed on a map of Denmark. A 95% and 99% threshold was applied to identify cells with excess incidence representing potential clusters. Four cells had excess incidence in all three time periods. The analysis in 25 different grid positions indicated a low risk of overlooking cells with excess incidence in a random grid. The coefficient of variation ranged from 0·08 to 0·11 independent of the threshold. By application of a random grid model we demonstrated that it was possible to detect small areas with excess incidence that were not detected in the present surveillance system.