It was observed that small children and pregnant women were affected to only a small extent by the H1N1 influenza outbreak of winter 1978–79. This supports earlier findings from the epidemic season of 1977–78 and demonstrates that the evolutionary changes in the epidemic virus were not reflected in any appreciable way in this curious phenomenon. The frequency of elderly subjects possessing antibodies against the epidemic H1N1 virus was low, and virtually equal in the pre-epidemic and post-epidemic sampling. This low attack rate contrasts with observations on young military servicemen, in whom the re-infection rate was high, thus indicating that the infection with the winter 1977–78 virus had conferred only modest protection against the closely related virus which caused the winter 1978–79 outbreak.

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.

1. Iodine vapour at a readily tolerable concentration of 0·1 mg./cu.ft. of air gives a rapid kill of freshly sprayed salivary organisms at humidities above 50 %.

2. At the same concentration dry bacteria are not as readily killed, the killing rate only becoming appreciable above 70 % R.H.

Norovirus is detected in one in five diarrhoea episodes in children, yet little is known about environmental risk factors associated with this disease, especially in low-income settings. The objective of this study was to examine environmental risk factors, and spatial and seasonal patterns of norovirus diarrhoea episodes in children in León, Nicaragua. We followed a population-based cohort of children under age 5 years for norovirus diarrhoea over a 1-year period. At baseline, characteristics of each household were recorded. Households were geocoded and spatial locations of garbage dumps, rivers, and markets were collected. In bivariate analysis we observed younger children and those with animals in their households were more likely to have experienced norovirus episodes. In adjusted models, younger children remained at higher risk for norovirus episodes, but only modest associations were observed with family and environmental characteristics. We next identified symptomatic children living in the same household and within 500 m buffer zones around the household of another child infected with the same genotype. Norovirus diarrhoea episodes peaked early in the rainy season. These findings contribute to our understanding of environmental factors and norovirus infection.

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.

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.

A new serological method, the platelet aggregation (PA) test, was used to study Group B arbovirus infections, which are often associated with thrombocytopenia. The method is based on the interaction of antigen-antibody complexes with platelets. The PA test was nearly as good as the haemagglutination-inhibition (HI) test for epidemiological studies of tick-borne encephalitis (16 out of 18 HI positive sera) and was superior to the complement-fixation test which was positive in 10 out of 18 HI positive sera. The PA test could be used in the serological diagnosis of Group B arbovirus infection. The titres with the PA test were of the same magnitude as the HI titres, and about ten times higher than the CF titres. Two pairs of dengue haemorrhagic fever sera showed high initial PA titres. The role of immune complexes in the pathogenesis of haemorrhagic fevers is discussed.

In an article on Pneumonoconiosis published in 1935 I attempted to simplify the problem of lung diseases caused by exposure to dust in industry by means of a classification which might allow of the placing of individual cases into appropriate categories. The importance of some such classification has been emphasized during the past year or so by the gradual realization of the fact that, especially in the South Wales coalfield, cases of more or less disabling lung conditions are frequently met with which cannot conscientiously be fitted into the category of “silicosis”, as defined at the International Conference at Johannesburg in 1930. These cases cannot be “certified” for compensation under existing Statutes, and yet present a picture of respiratory distress and dyspnoea on exertion which marks them out as quite unfit for work.

Historical outbreaks can be an important source of information in the understanding of norovirus evolution and epidemiology. Here, we revisit an outbreak of undiagnosed gastroenteritis that occurred in Shippensburg, Pennsylvania in 1972. Nearly 5000 people fell ill over the course of 10 days. Symptoms included diarrhea, vomiting, stomach cramps, and fever, lasting for a median of 24 h. Using current techniques, including next-generation sequencing of full-length viral genomic amplicons, we identified an unusual norovirus recombinant (GII.Pg/GII.3) in nine of 15 available stool samples from the outbreak. This particular recombinant virus has not been reported in recent decades, although GII.3 and GII.Pg genotypes have been detected individually in current epidemic strains. The consensus nucleotide sequences were nearly identical among the four viral genomes analysed, although each strain had three to seven positions in the genome with heterogenous non-synonymous nucleotide subpopulations. Two of these resulting amino acid polymorphisms were conserved in frequency among all four cases, consistent with common source exposure and successful transmission of a mixed viral population. Continued investigation of variant nucleotide populations and recombination events among ancestral norovirus strains such as the Shippensburg virus may provide unique insight into the origin of contemporary strains.

In developed countries the majority of hepatitis C virus (HCV) infections occur in injecting drug users (IDUs) with prevalence in IDUs often high, but with wide geographical differences within countries. Estimates of local prevalence are needed for planning services for IDUs, but it is not practical to conduct HCV seroprevalence surveys in all areas. In this study survey data from IDUs attending specialist services were collected in 52/149 sites in England between 2006 and 2008. Spatially correlated random-effects models were used to estimate HCV prevalence for all sites, using auxiliary data to aid prediction. Estimates ranged from 14% to 82%, with larger cities, London and the North West having the highest HCV prevalence. The methods used generated robust estimates for each area, with a well-identified spatial pattern that improved predictions. Such models may be of use in other areas of study where surveillance data are sparse.

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 study aimed to estimate the natural history and transmission parameters based on experimental viral shedding and symptom dynamics in order to understand the key epidemiological factors that characterize influenza (sub)type epidemics. A simple statistical algorithm was developed by combining a well-defined mathematical scheme of epidemiological determinants and experimental human influenza infection. Here we showed that (i) the observed viral shedding dynamics mapped successfully the estimated time-profile of infectiousness and (ii) the profile of asymptomatic probability was obtained based on observed temporal variation of symptom scores. Our derived estimates permitted evaluation of relationships between various model-derived and data-based estimations, allowing evaluation of trends proposed previously but not tested fully. As well as providing insights into the dynamics of viral shedding and symptom scores, a more profound understanding of influenza epidemiological parameters and determinants could enhance the viral kinetic studies of influenza during infection in the respiratory tracts of experimentally infected individuals.

Substantial reduction in the bacterial content of the air of an empty room after infection with B. prodigiosus (or with Staphylococcus albus or a diphtheroid bacillus) has been effected by means of hypochlorites introduced into the air by atomization from a Dynalysor or by spraying from a flit gun.

The ‘normal’ variation of the bacterial content of the air of an occupied (crowded) room has been described.

Repeated spraying of a solution containing 1% of sodium hypochlorite or of a 1·3% suspension of water-sterilizing powder (bleaching powder) from a flit gun has been shown to reduce materially the bacterial content of the air of the occupied room.

Similar sprayings of water have been shown to have no appreciable effect on the bacterial content of the air of the occupied room and the action of the hypochlorite was, therefore, not merely a mechanical removal of bacteria from the air.

Methods have been devised for assessing the degree of disinfection per individual spraying of hypochlorite, and, although the methods are mainly of comparative value, it may be stated that the reduction in the total bacterial content of the air of the occupied room for a single spraying of hypochlorite Y (≡1% sodium hypochlorite) was of the order of 33%, or more. The percentage reduction of potentially pathogenic bacteria which may have been present was almost certainly greater than the reduction of the total bacterial content, which included resistant saprophytic bacteria. The average concentration of hypochlorite Y used in these experiments was 0·38 c.c. per million c.c. of air (i.e. less than 11·0 c.c. per 1000 cu. ft. of air) per spraying, i.e. was exceedingly small, and even smaller concentrations were equally effective when the hypochlorite was atomized into the air by means of the Dynalysor.

Rather less consistent results were obtained with the chemically less active bleaching powder suspension than with hypochlorite Y in the flit-gun experiments.

The relative humidity of the air has been shown to be a factor of great importance, and in the experiments described in this paper effective air disinfection was not obtained at low relative humidities at temperatures ranging from 54 to 74° F. The need for accurate determination of the critical lower limit of relative humidity is stressed.

Tobacco smoke has been shown to reduce the efficiency of hypochlorite sprays but the experimental evidence was insufficient for any definite conclusion to be drawn.

The advantages and disadvantages of hypochlorites as air disinfectants have been discussed and the conclusion reached that repeated (every 20 or 30 min.) spraying of the air of an occupied room with a 1% solution of hypochlorite (e.g. hypochlorite Y) constitutes a simple, practical, inexpensive and efficient method of air disinfection, and, provided simple precautions are observed, there are no serious objections to such a procedure.

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.

The bactericidal activity of natural sea-water on S. typhi is due to the combined effect of pH, salinity, toxic ions, presence of competitor and predator marine organisms, unidentified heat-labile toxic substances and competition for the limited food supply. Sea-water subjected to filtration and autoclaving lost the major part of its bactericidal activity. It is concluded that predators and competitors contribute significantly to the rapid death of S. typhi in raw sea-water. The addition of peptone decreases the bactericidal activity of sea-water. The fluctuations in the total number of competitors and predators in sea-water together with the fluctuations in the concentration of heavy metal ions may be affected by various factors. Such fluctuations are probably responsible for the variable bactericidal action of different sea-water samples.

Bathing in sewage-polluted sea-water carries with it a health risk in spite of the excessive dilution of pathogenic micro-organisms in the sea and the rapid self-purification process of sea-water. The natural purifying processes are incapable of coping with massive pollution problems and should not be relied on as the sole protection offered to users of sea-water.

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

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.

Sera collected from the indigenous population of the Tana River valley during the Tana River Expedition in 1976 were examined for neutralizing antibody to Tanapox virus. Antibody was found in 9·2% of the population in infected areas. This result and the presence of antibody in four children indicated that infection had continued to occur in the area since the 1962 outbreak.

In September 2009, the Rensselaer County Department of Health investigated an increase in Giardia duodenalis cases. The epidemiological investigation identified that a source of the illness could be a roadside spring located in the eastern part of the county. Epidemiological and environmental health staff conducted a site visit to the roadside spring and found several concerns. Water samples were collected from the roadside spring and sent to the New York State Department of Health for analysis. The water sample results indicated the presence of empty Giardia cysts. Prevention methods occurred and the roadside spring was destroyed. A total of 36 laboratory-confirmed cases of Giardia were identified from this outbreak that included residents of New York State and Massachusetts.

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.