1. The recovery, after poisoning, of the rat population of eight sewer systems was measured by the bait-census method.

2. In three of the systems the mean rate of increase was of the order of 3% per week. This is attributed solely to breeding and is regarded as typical for rats in sewers.

3. Higher rates of increase (up to 11·8%) were also recorded but are believed to have been partly due to immigration or to have been only apparent (as a result of census difficulties).

4. The consequences for control of a rate of increase as low as 3% per week are discussed.

Our thanks are due to eight Local Authorities, their Chief Public Health Officers and members of their staffs, without whose help the work would have been impossible, and to a number of colleagues, especially Mr J. H. Greaves, who helped with much of the census work.

A pandemic influenza A(H1N1) 2009 outbreak in a summer school affected 117/276 (42%) students. Residential social contact was associated with risk of infection, and there was no evidence for transmission associated with the classroom setting. Although the summer school had new admissions each week, which provided susceptible students the outbreak was controlled using routine infection control measures (isolation of cases, basic hygiene measures and avoidance of particularly high-risk social events) and prompt treatment of cases. This was in the absence of chemoprophylaxis or vaccination and without altering the basic educational activities of the school. Modelling of the outbreak allowed estimation of the impact of interventions on transmission. These models and follow-up surveillance supported the effectiveness of routine infection control measures to stop the spread of influenza even in this high-risk setting for transmission.

1. Investigation by American bactriologists have shown that the lactose-fermenting (gas-producing) bacilli can be divided into two main types distinguishabel by the methyl-red and Voges-Proskauer reactions.

2. The methyl-red- Voges-Proskauer + type are shwon to be rare in human and animal faeces, more common in surface water, milk and sewage, and the predominant type in soil and grain, and to be more resistant than the methyl-red + Voges-Proskauer-type.

3. Investigations by the author of this paper confirm their findings as regards human and animal faeces, water, milk and grain. An investigation of the types present in soil is being undertaken and it is hoped to publish an account of this later. Already the “M.R.—” type has been found to predominate in four out of six samples of soil.

4. In the present investigation organisms of the “M.R.—” type were found in 66 samples of water out of a total of 200 containing lactose-fermenters, and in 41 samples containing this type no evidence of recent contamination could be adduced by the search for organisms of the “M.R.+” type ofStreptococci. Judgment of the water was therfore liable to modifiction in 20% of these samples by the recognition of this type.

5. Twenty-nineout of the 66 samples containing organisms of the “M.R.—” type were from sources of good repute, most of them from public supplies.

6. The presence of lactose-formenters of the “M.R.—”“V.P.+” type must be regarded with considerable less disfavour than the presence of “M.R.+” “V.P.—” organisms, and the application of tests for the recognition of these types is impotant. It is suggested that these tests should be included in all routine examinations of water and food products.

In conclusion I have pleasue in acknowledging my indebtedness to Dr. W.G.Savage for calling my attention to the reserches of American bacteriologist and for many valuable suggestions he has made in connection with this work.

Household contacts of an index case of invasive meningococcal disease (IMD) are at increased risk of acquiring disease. In revising WHO guidance on IMD in sub-Saharan Africa, a systematic review was undertaken to assess the effect of chemoprophylaxis and of vaccination in preventing subsequent cases of IMD in household contacts following an index case. A literature search for systematic reviews identified a single suitable review on chemoprophylaxis in 2004 (three studies meta-analysed). A search for primary research papers published since 2004 on chemoprophylaxis and without a date limit on vaccination was therefore undertaken. There were 2381 studies identified of which two additional studies met the inclusion criteria. The summary risk ratio for chemoprophylaxis vs. no chemoprophylaxis (four studies) in the 30-day period after a case was 0·16 [95% confidence interval (CI) 0·04-0·64, P = 0·008]; the number needed to treat to prevent one subsequent case was 200 (95% CI 111-1000). A single quasi-randomized trial assessed the role of vaccination. The risk ratio for vaccination vs. no vaccination at 30 days was 0·11 (95% CI 0·01–2·07, P = 0·14). The results support the use of chemoprophylaxis to prevent subsequent cases of IMD in household contacts of a case. Conclusions about the use of vaccination could not be drawn.

Restriction digest fragments of DNA from 46 clinical isolates identified as Corynebacterium group D2, were separated by electrophoresis, Southern blotted onto nylon membranes and hybridized to a ribosomal RNA gene probe. The resulting band patterns were subjected to unweighed pair-group cluster analysis. Representative strains from the main clusters were compared with similarly prepared band patterns from type strains of human Corynebacterium species.

The results indicate that strains identified as Corynebacterium group D2 represent a unique taxon and that computer-assisted analysis of rRNA gene restriction fragment polymorphism (ribotyping) could be a useful technique in epidemiological studies of these bacteria.

1. Data obtained by the disinfection at 51° C. of standard cultures of Bact. coli at pH values ranging from 2·8 to 8·8 have been used for the calculation of the concentration exponents of hydrogen and hydroxyl ions. The times taken to reach various degrees of mortality from 50 to 99·99 % have been taken as measures of the activities of the ions.

2. The formula Cn×t = constant proved satisfactory for describing the data for all the mortality levels and at all the pH values tested except pH 2·8, 6·25, 6·4 and 7·0. In these instances the cultures exhibited heightened sensitivity, though the results at all, except pH 2·8, could be included when the 99·.99 % mortality times were used. The exponents increased sharply at pH values below 3·9.

3. The values of the concentration exponents varied similarly under both acid and alkaline conditions, according to the mortality level chosen. The largest value was obtained from the 90 % mortality times, there being a decrease when both higher and lower levels were employed. The changes were greater under acid conditions, when the values ranged from 0·60 to 0·25, compared with 0·60–0·47 for the alkaline reactions.

4. The mean of the pH values for maximal survival at the various mortality levels, derived from the regressions of log mortality time on pH, was ·51, but this was close to a point of greater susceptibility. Experimentally, maximal survival occurred at pH 6·65, which is very near to the neutral point of water at 51° C.

5. It is concluded that within the pH range 6·25–7.0 the hydrogen and hydroxyl ions were relatively inactive, the effects observed being due to other factors possibly including the action of undissociated water molecules.

The authors acknowledge with thanks the receipt of a grant from Messrs I.C.I. (Pharmaceuticals) Ltd. towards the expenses of this investigation.

The present communication deals with an analysis and comparison of the principal physical measurements, physical characters and relative bodily proportions in groups of boys and girls at corresponding ages who were under treatment for asthma and rheumatism respectively in the special clinics established at the Sick Children's Hospital, Great Ormond Street, and of other groups of boys and girls of similar ages with no history of asthma or rheumatism and no obvious serious impairment of general health who were attending the Outdoor Department of the hospital for treatment of trivial ailments. The last-mentioned series of boys and girls have been assumed to represent the normal hospital population and have been referred to throughout as the normal groups. The object of the investigation was to determine if there was any real evidence that the asthmatic and rheumatic children differed from one another or from the normal children in general physical type or build. The inquiry has been restricted to children in the age period 6–12 years, and these have been taken in two-yearly age groups in order to provide more adequate numbers of observations for comparison. In all, the characters of approximately 1212 children have been dealt with. Of these, 368, 236 boys and 132 girls; 459, 189 boys and 270 girls; and 385, 195 boys and 190 girls, were considered to be asthmatic, rheumatic and normal respectively. A study of the frequency distributions, mean values and variabilities of the characters compared at the corresponding ages in the three groups of boys and girls seems to provide a reasonable basis for the following conclusions:

1. The corresponding averages of practically all the absolute physical measurements brought under review are in such close agreement in the contrasted groups of asthmatic and rheumatic children that the data provide no evidence of any real difference in the general dimensions of children with the respective diseases. Though the average antero-posterior diameter of the chest is probably greater in the asthmatic than the rheumatic children, no emphasis can be laid on this feature as it may be, in part, the result of the disease.

2. Though at some ages the mean dimensions of a few characters in the asthmatic and rheumatic groups do differ from the corresponding averages in the normal series, the differences are not sufficiently consistent at the different ages and in the two sexes to indicate any real divergence from the normal.

3. A comparison of the relative proportions of the body as expressed by the percentage ratios or indices, stem length/stature, body length/stature, biacromial diameter/body length, bicristal diameter/biacromial diameter and length of arm/length of leg, at corresponding ages in the asthmatic and rheumatic children does not provide any definite evidence that children suffering from these two diseases differ from one another in morphological type.

4. Though occasionally, at one or more ages, one or more of the indices used to express the relative proportions of the body may appear to differ in mean value from the normal averages at the corresponding ages the differences are not sufficiently consistent in regard to age and sex to suggest any real divergence from the normal.

5. Comparison of the frequency distributions of hair colour shows that the asthmatic children do not really differ from the rheumatic children in respect of pigmentation. The rheumatic children do not differ from the normal, but both the asthmatic boys and girls show a relatively greater excess of the blonde haired type and a greater deficiency in the dark haired as compared with the normal than might be expected to occur as a chance variation.

6. With regard to distribution of eye colour, the asthmatic boys do not differ from the rheumatic boys, but the asthmatic girls appear to have a relative defect in brown eyes and a relative excess in blue eyes as compared with the rheumatic group; neither in boys nor girls with asthma or rheumatism can the distribution of eye colour be said to differ significantly from the normal on the data available.

7. There is no definite evidence that the proportions of relatively long and slender and short and thick-set types, as appraised by general inspection, amongst asthmatics differ from the normal.

8. There is no evidence in the data for boys or girls that the distribution of grades of posture differs significantly in either the asthmatic or rheumatic groups from the normal, though in girls with rheumatism the habitual posture appears to be relatively worse than in those with asthma.

9. Both in regard to form of face, as expressed by the upper and total facial indices, and form of head, as represented by the cephalic index, the groups of asthmatic and rheumatic children do not differ significantly from one another or from the normal.

10. The differences in the three groups of children, the asthmatic, the rheumatic and the normal, in respect of the aggregate of physical characters brought under review are relatively so slight that they cannot be considered to support the view that asthmatic and rheumatic children really differ on the average from one another or from the general population of children from which they are drawn in bodily conformation or physical type, though they may possibly, indeed probably, differ in other constitutional traits.

The number of reported cases with Legionnaires' disease (LD) is increasing in Belgium. Previous studies have investigated the associations between LD incidence and meteorological factors, but the Belgian data remained unexplored. We investigated data collected between 2011 and 2019. Daily exposure data on temperature, relative humidity, precipitation and wind speed was obtained from the Royal Meteorological Institute for 29 weather stations. Case data were collected from the national reference centre and through mandatory notification. Daily case and exposure data were aggregated by province. We conducted a time-stratified case-crossover study. The ‘at risk’ period was defined as 10 to 2 days prior to disease onset. The corresponding days in the other study years were selected as referents. We fitted separate conditional Poisson models for each day in the ‘at risk’ period and a distributed lag non-linear model (DLNM) which fitted all data in one model. LD incidence showed a yearly peak in August and September. A total of 614 cases were included. Given seasonality, a sequence of precipitation, followed by high relative humidity and low wind speed showed a statistically significant association with the number of cases 6 to 4 days later. We discussed the advantages of DLNM in this context.

We sought to examine the factors associated with bacteraemia and their outcome in children with pneumonia and severe acute malnutrition (SAM). All SAM children of either sex, aged 0–59 months, admitted to the Dhaka Hospital of the International Centre for Diarrhoeal Disease Research, Bangladesh with radiologically confirmed pneumonia from April 2011 to July 2012 were enrolled (n = 405). Comparison was made between pneumonic SAM children with (cases = 18), and without (controls = 387) bacteraemia. The death rate was significantly higher in cases than controls (28% vs. 8%, P < 0·01). In logistic regression analysis, after adjusting for potential confounders, the SAM children with pneumonia and bacteraemia more often had a history of lack of bacillus Calmette-Guérin (BCG) vaccination (odds ratio 7·39, 95% confidence interval 1·67–32·73, P < 0·01). The results indicate the importance of continuation of BCG vaccination which may provide benefit beyond its primary purpose.

Identification of covariates associated with disease is a key part of epidemiological research. Yet, while adjustment for imperfect diagnostic accuracy is well established when estimating disease prevalence, similar adjustment when estimating covariate effects is far less common, although of important practical relevance due to the sensitivity of such analyses to misclassification error. Case-study data exploring evidence for seasonal differences in Salmonella prevalence using serological testing is presented, in addition simulated data with known properties are analysed. It is demonstrated that: (i) adjusting for misclassification error in models comprising continuous covariates can have a very substantial impact on the resulting conclusions which can then be drawn from any analyses; and (ii) incorporating prior knowledge through Bayesian estimation can provide potentially more informative assessments of covariates while removing the assumption of perfect diagnostic accuracy. The method presented is widely applicable and easily generalized to many types of epidemiological studies.

Multiple cases of atypical scrapie in the same holding and co-existence with classical scrapie have been reported in Great Britain. A two-stage simulation tool was developed by combining a sampling algorithm and a hierarchical Bayesian model to simulate the number of positive cases of atypical scrapie from: (i) random sampling and (ii) using the actual sampled population in Great Britain, being the output probability of detection of flocks with one and more cases. Cluster analysis was conducted to assess the level of geographical over- and under-sampling over the years. The probability of detecting at least two cases of atypical scrapie in the same holding is much lower in simulated random data than in simulated actual data for all scenarios. Sampling bias in the selection of sheep for testing led to multiple sampling from fewer but larger holdings, Scotland, and areas of Wales were under-sampled and the South-West and East of England oversampled. The pattern of atypical scrapie cases observed is unlikely to be explained by a multi-case event epidemiologically linked. The co-existence of classical and atypical scrapie is a rare event with 19 holdings detected in GB and does not suggest an epidemiological link between the two types of disease.

Measles virus-specific antibodies in sera from patients with HBsAg-negative chronic active hepatitis and raised antibody titres against measles virus, have been examined by crossed immunoelectrophoresis. The immunoprecipitates were further analysed by SDS-polyacrylamide gel electrophoresis. Five measles virus-specific precipitation lines were demonstrated using measles virus-infected cells solubilized with Triton X-100. The three major precipitation lines were analysed by SDS-PAGE and contained the virus polypeptides: nucleoprotein, NP (MW ∼ 60000); haemoagglutinin, H (MW ∼ 80000) and fusion protein F1 (MW ∼ 40000). Considerably higher amounts of antibodies against these three virus polypeptides were demonstrated in the patient sera than in sera from healthy controls. By SDS-PAGE analysis of radiolabelled immune complexes adsorbed to Sepharose-protein A, antibodies against five measles virus polypeptides: NP, H, F1, P protein (MW ∼ 70000) and matrix protein, M (MW ∼ 37000) were demonstrated in the patient sera.

A case-control study was conducted in the urban area of Attica, Greece to investigate risk factors for sporadic Campylobacter jejuni infections in children aged <15 years. Over a 2-year period, 205 cases and 205 controls, matched by age group (<1, 1–4, 5–9, 10–14 years) and gender, were selected from the registries of the paediatric hospitals of this area. In conditional multivariate logistic regression analysis, ethnicity [odds ratio (OR) 5·06, 95% confidence interval (CI) 2·49–10·28], consumption of chicken the week prior to disease onset (OR 1·97, 95% CI 1·10–3·55) and playing in the garden (OR 1·83, 95% CI 1·05–3·19) were independently associated with disease occurrence; consumption of raw vegetables was a ‘protective’ factor (OR 0·48, 95% CI 0·27–0·85).

The prevalence of metallo-β-lactamase (MBL) production among Pseudomonas aeruginosa nosocomial isolates from a Brazilian teaching hospital was determined. A total of 512 P. aeruginosa isolates were recovered from 245 patients during a 10-month period. Ninety-four (38·4%, 95% CI 32·2–44·8%) isolates were MBL producers. Most resistance to β-lactams was mediated by MBL. Forty-one (16·7%) were resistant to all drugs except polymyxin B and 33 (80·5%) of these were MBL producers. Clonal dissemination, documented by DNA macrorestriction, played a major role for the spread of MBL isolates. The blaSPM-1 gene was demonstrated by PCR in 14 randomly selected MBL isolates. The extremely high prevalence of MBL production found challenges the choice of therapeutics for P. aeruginosa, and measures to control horizontal dissemination of MBL producers are urgently required.

This study aims to describe changes in incidence and risk factors for community-associated methicillin resistant Staphylococcus aureus (CA-MRSA) infections upon admission to two New York City hospitals from 2006 to 2012. We examined the first hospitalization for adult patients using electronic health record and administrative data and determined the annual incidence/1000 admissions of total S. aureus, total MRSA, and CA-MRSA (within 48 h of admission) in clinical specimens over the study period. Logistic regression was used to identify factors associated with CA-MRSA in 2006 and 2012. In 137 350 admissions, the incidence of S. aureus, MRSA, and CA-MRSA/1000 admissions were 15·6, 7·0, and 3·5, respectively. The total S. aureus and MRSA isolations decreased significantly over the study period (27% and 25%, respectively) while CA-MRSA incidence was unchanged. CA-MRSA increased as a proportion of all MRSA between 2006 (46%) and 2012 (62%), and was most frequently isolated from respiratory (1·5/1000) and blood (0·7/1000) cultures. Logistic regression analysis of factors associated with isolation of CA-MRSA showed that age ⩾65 years [odds ratio (OR) 2·3, 95% confidence interval (CI) 1·2–4·5], male gender (OR 1·8, 95% CI 1·2–2·8) and history of renal failure (OR 2·6, 95% CI 1·6–4·2) were significant predictors of infection in 2006. No predictors were identified in 2012.

Europe is in the midst of a COVID-19 epidemic and a number of non-pharmaceutical public health and social measures have been implemented, in order to contain the transmission of severe acute respiratory syndrome coronavirus 2. These measures are fundamental elements of the public health approach to controlling transmission but have proven not to be sufficiently effective. Therefore, the European Centre for Disease Prevention and Control has conducted an assessment of research gaps that can help inform policy decisions regarding the COVID-19 response. We have identified research gaps in the area of non-pharmaceutical measures, physical distancing, contact tracing, transmission, communication, mental health, seasonality and environment/climate, surveillance and behavioural aspects of COVID-19. This prioritisation exercise is a step towards the global efforts of developing a coherent research road map in coping with the current epidemic but also developing preparedness measures for the next unexpected epidemic.

Hepatitis B virus (HBV) can be eliminated by effective universal vaccination. In Belgium, a free-of-charge HBV vaccination programme in infants with catch-up in adolescents was introduced in 1999. To evaluate the effects in <20-year-olds, seroprotection (anti-HBs >11 mIU/ml, according to the assay) and markers of infection (anti-HBc, HBsAg) were assessed in 2443 residual sera collected 7–8 years after implementation of the programme. The maximal prevalence of a solely anti-HBs seroprotective (‘vaccinated’) serostatus was 82·9% at age 1 year and 60·5% at age 13 years. A clear increase was found in age cohorts targeted by the campaign after a similar serosurvey conducted 4 years earlier. The prevalence of HBV infection remained unchanged at a low level (1·8% in 2006) similar to pre-vaccination data (1993–1994). We conclude that universal HBV vaccination has achieved overall high levels of vaccine-induced immunity, despite regional variations, which may give rise to pockets of susceptible young adults in the future.

At present, the number of people with tuberculosis in China is second only to India and ranks second in the world. Under such a severe case of tuberculosis in China, prevention and control of pulmonary tuberculosis are urgently needed. This study aimed to study the temporal and geographical relevance of the pathogenesis of pulmonary tuberculosis and the factors affecting the incidence of tuberculosis. Spatial autocorrelation model was used to study the spatial distribution characteristics of pulmonary tuberculosis from a quantitative level. The research results showed that the overall incidence of pulmonary tuberculosis (IPT) in China was low in the east, high in the west and had certain seasonal characteristics. We use Spatial Lag Model to explore influencing factors of pulmonary tuberculosis. It indicates that the IPT is high in areas with underdeveloped economics, poor social services and low average smoking ages. Additionally, the IPT is high in areas with high AIDS prevalence. Also, compared with Classical Regression Model and Spatial Error Model, our model has smaller values of Akaike information criterion and Schwarz criterion. Besides, our model has bigger values of coefficient of determination (R2) and log-likelihood (log L) than the other two models. Apart from that, it is more significant than Spatial Error Models in the spatial dependence test for the IPT.

To better understand hepatitis C virus (HCV) epidemiology in Punjab state, India, we estimated the distribution of HCV antibody positivity (anti-HCV+) using a 2013–2014 HCV household seroprevalence survey. Household anti-HCV+ clustering was investigated (a) by individual-level multivariable logistic regression, and (b) comparing the observed frequency of households with multiple anti-HCV+ persons against the expected, simulated frequency assuming anti-HCV+ persons are randomly distributed. Village/ward-level clustering was investigated similarly. We estimated household-level associations between exposures and the number of anti-HCV+ members in a household (N = 1593 households) using multivariable ordered logistic regression. Anti-HCV+ prevalence was 3.6% (95% confidence interval 3.0–4.2%). Individual-level regression (N = 5543 participants) found an odds ratio of 3.19 (2.25–4.50) for someone being anti-HCV+ if another household member was anti-HCV+. Thirty households surveyed had ⩾2 anti-HCV+ members, whereas 0/1000 (P < 0.001) simulations had ⩾30 such households. Excess village-level clustering was evident: 10 villages had ⩾6 anti-HCV+ members, occurring in 31/1000 simulations (P = 0.031). The household-level model indicated the number of household members, living in southern Punjab, lower socio-economic score, and a higher proportion having ever used opium/bhuki were associated with a household's number of anti-HCV+ members. Anti-HCV+ clusters within households and villages in Punjab, India. These data should be used to inform screening efforts.

At the beginning of the war, the London County Counoil issued a report by Sir Frederick Menzies, their late School Medical Officer, on the average heights and weights of London elementary school children in 1938. The report is based on the measurements of about 100,000 children, and is probably the most important contribution to the anthropometry of childhood that has appeared in this country for many years.