The rapid decline of the birth-rate in nearly all countries of western Europe has naturally attracted much attention. Some have studied the probable effects upon the absolute size and the age constitution of the population, and the consequence entailed upon the military and economic strength of a nation. Others have drawn attention to resulting change's in the relative importance of diseases of young, adult and old ages. Changes in mere numbers depend wholly, and the other changes to a considerable extent, upon quantitative factors; they must occur even if the quality of those born differs in no way from that of those produced when fertility was at a higher level. But, if the quality of births changes with their quantity, then the consequences of decrease of numbers may be better or worse than mere numerical changes would involve.

In recent years, methicillin–resistant Staphylococcus aureus (MRSA) isolates in Spain have increased dramatically; in 1986 there were only 1.2% MRSA amongst all nosocomial Staphylococcus aureus (SA) isolates, by 1989 this percentage had risen to 44% in some hospital causing a very serious epidemic situation in the country. We have characterized these isolates by direct, reverse and Fisk phage typing and we have also looked for an additional local set of phages to help us to differentiate these strains. We have been able to differentiate an epidemic strain from other MRSA strains which cause sporadic hospital outbreaks, and we have also distinguished between some variants of the epidemic strain.

Bacillus dysenteriae Flexner (Shigella paradysentriae) grown on Lemco agar plates (without peptone) containing sulphanilamide 1/20,000 to 1/10,000 forms papillae which on subculture yield two strains: (1) the original strain unmodified and (2) a strain resistant to SA.

The latter has arisen by discontinuous variation. There are no forms intermediate between strain (1) and strain (2).

In one such case (Exp. 1, p. 334) the no-contact race, the unmodified non-resistant strain from the primary sulphanilamide plate and the resisting variant strain were titrated in broth containing sulphanilamide in ten increasing concentrations from 1/34,000 to 1/5000. The first two strains, the no-contact and the unmodified non-resistant from the sulphanilamide plate grew in SA 1/34,000 and failed in 1/21,000, while the resisting variant grew up to the tube containing SA 1/6000 and failed to grow in 1/5000.

On plates containing sulphanilamide this adaptive variation takes place only in the papillae. It can also take place in broth containing, for example, SA 1/20,000 to 1/10,000.

There is no such thing as gradual progressive acquisition of resistance by the whole of a bacterial population exposed to a drug. Such phrases as ‘teaching bacteria to resist’ are misleading and anthropomorphic and should not be employed.

Fluid cultures which show a progressive gradual increase of resistance do so as a result of an increasing percentage of resistant cells in a mixed population of resistant and non-resistant bacteria. Experiments in fluid media should always be checked and the growth analysed by plating.

Resistant strains maintain this character after prolonged growth on drug-free media.

(2) Flexner's dysentery bacillus grown on plates containing acriflavine 1/60,000 to 1/40,000 forms in papillae strains resistant to this drug. The non-papillary areas of colonies die early, viz. on the 3rd day. The variation in this case also is discontinuous.

(3) On the other hand, if Flexner's bacillus is grown on agar containing organic compounds of silver or arsenic (argyrol or neosalvarsan), it forms no variants resisting these drugs.

(4) Papillae possess two biological functions: (a) they are the site of adaptive variation in response to elements in their environment, such as harmful drugs or useful sugars; (6) they are also the site of rejuvenation of senile cells and of cells affected by common unfavourable conditions such as exhaustion of food supply and accummulation, of excretory substances.

The greatest development of papillae takes place on plates which form no variants, such as plates of drug-free agar, agar plates containing sulphanilamide sown with strains resistant to sulphanilamide and plates containing organic compounds of silver or arsenic.

During an epidemic of Sonne dysentery in Tooting Bec Hospital of which the epidemiological aspects have been described by one of us (Buckle, 1938), and during a recurrence of this epidemic, a number of strains were isolated of the causal organism (140) and various bacilli which were somewhat similar in their cultural and biochemical behaviour. It was thought that a close bacteriological and serological examination of these might be useful in giving information about the constancy of behaviour of the Sonne group, the question of possible biochemical subgroups of Sonne bacilli (Bojlén. 1934), and the relationship of the dysenteroid organisms isolated to the true dysentery bacilli, their classification, and significance.

In the third week of September 2022, an outbreak of measles was reported from a slum in Eastern Mumbai, India. We sought to investigate whether failure to vaccinate or vaccine failure was the cause. We constructed an epidemic curve, drew a spot map, and calculated the attack rate and case-fatality ratio. We calculated vaccine effectiveness (VE) for one and two doses of measles vaccine in an unmatched case–control study and did stratified analysis by sex, availability of vaccination card, and migrant status. We identified 358 cases and four deaths with a 11.3% attack rate and 1.1% case fatality, both being highest among 0–24-month-old boys. The epidemic curve suggested a propagated mode of spread. The VE for two doses was 64% (95% confidence interval (CI): 23–73%) among under-5-year-old children and 70% (95% CI: 28–88%) among 5–15-year-old children. Failure to vaccinate, consequent to the COVID-19 pandemic, and vaccine hesitancy might have led to the accumulation of susceptible children in the community. Additionally, the occurrence of case-patients among vaccinated suggests reduced VE, which needs further investigation into humoral and cell-mediated immunity as well as contributory factors including nutritional status. Outbreak response immunization to complete immunization of missed and dropout children was carried out to control the outbreak.

As one of the most neglected zoonotic diseases, brucellosis has posed a serious threat to public health worldwide. This study is purposed to apply different machine learning models to improve the prediction accuracy of human brucellosis (HB) in Shaanxi, China from 2008 to 2020, under livestock husbandry intensification from a spatiotemporal perspective. We quantitatively evaluated the performance and suitability of ConvLSTM, RF, and LSTM models in epidemic forecasting, and investigated the spatial heterogeneity of how different factors drive the occurrence and transmission of HB in distinct sub-regions by using Kernel Density Analysis and Shapley Additional Explanations. Our findings demonstrated that ConvLSTM network yielded the best predictive performance with the lowest average RMSE of 13.875 and MAE values of 18.393. RF model generated an underestimated outcome while LSTM model had an overestimated one. In addition, climatic conditions, intensification of livestock keeping and socioeconomic status were identified as the dominant factors that drive the occurrence of HB in Shaanbei Plateau, Guanzhong Plain, and Shaannan Region, respectively. This work provided a comprehensive understanding of the potential risk of HB epidemics in Northwest China driven by both anthropogenic activities and natural environment, which can support further practice in disease control and prevention.

The brucellin skin test and the lymphocyte transformation test were compared in heifers infected with virulent Brucella abortus strain 544, heifers vaccinated against brucellosis and unexposed cattle. Results of the in vitro lymphocyte transformation test were consistently positive for all 9 Brucella-infected heifers while the skin test was consistently positive for 6 of the 9 heifers. In 7 heifers repeatedly vaccinated with B. abortus strain-19 vaccine the in vitro test classified 3 animals as positive whereas the skin test identified all the animals as infected during most of the experimental period. Four heifers injected with a single dose of B. abortus strain 19 were consistently negative to the lymphocyte transformation test while the skin test classified all the animals as infected during most of the experimental period. The skin test gave strong reactions indicative of Brucella infection in heifers vaccinated with ‘Duphavac’ and ‘Abortox’ vaccines whereas the lymphocyte transformation test was consistently negative with these vaccines. The two tests were negative in unexposed cattle. It was concluded that the in vitro test correlated better with Brucella isolation than the in vivo test did and that the lack of agreement between the results of the two tests is likely to be due to the different antigens used in the assays.

Three influenza A (H3N2) reassortant whole virus vaccine strains with differing antibody-inducing capacities in hamsters were investigated morphologically and antigenically. Although initial measurements of virion circumference, from electron micrographs of vaccine preparations, suggested a relationship of small virion size with low immunogenicity, subsequent immunization with, and morphological investigation of, vaccine virions separated on sucrose gradients, failed to obtain populations whose antibody-inducing capacity clearly correlated with constituent virion density, size, morphology or integrity.

However, antigenic investigation using single radial haemolysis (SRH) and monoclonal antibodies revealed significant differences in antigenic specificity between the strains. Furthermore, a series of H3N2 isolates, derived using standard reassortment procedures, also showed differences in antigenic specificity in their haemagglutination-inhibition (HI) reactions with monoclonal antibodies after five passages in allantois-on-shell cultures. Variation between these isolates and their A/Victoria parent virus could be detected using SRH and hamster sera raised against each isolate.

These results demonstrate variation between candidate influenza A virus vaccine strains, all possessing the same surface (H3N2) glycoproteins, expressed as a consequence of the reassortant system used for their production.

Denmark hosted four games during the 2020 UEFA European championships (EC2020). After declining positive SARS-CoV-2 test rates in Denmark, a rise occurred during and after the tournament, concomitant with the replacement of the dominant Alpha lineage (B.1.1.7) by the Delta lineage (B.1.617.2), increasing vaccination rates and cessation of several restrictions. A cohort study including 33 227 cases was conducted from 30 May to 25 July 2021, 14 days before and after the EC2020. Included was a nested cohort with event information from big-screen events and matches at the Danish national stadium, Parken (DNSP) in Copenhagen, held from 12 June to 28 June 2021. Information from whole-genome sequencing, contact tracing and Danish registries was collected. Case–case connections were used to establish transmission trees. Cases infected on match days were compared to cases not infected on match days as a reference. The crude incidence rate ratio (IRR) of transmissions was 1.55, corresponding to 584 (1.76%) cases attributable to EC2020 celebrations. The IRR adjusted for covariates was lower (IRR 1.41) but still significant, and also pointed to a reduced number of transmissions from fully vaccinated cases (IRR 0.59). These data support the hypothesis that the EC2020 celebrations contributed to the rise of cases in Denmark in the early summer of 2021.

This study aimed at comparing the factors associated with the natural progression between typical progressors (TPs) and rapid progressors (RPs) in HIV-infected individuals. A retrospective study was conducted on 2095 eligible HIV-infected individuals from 1995 to 2016 in a high-risk area of Henan Province, China. Propensity score matching was used to balance covariates, and the conditional logistic regression analyses were performed to explore the factors of natural disease progression among HIV infectors. A total of 379 pairs of RPs and TPs were matched. The standardised difference values of all covariates were less than 10%. HIV-infected individuals transmitted through sexual transmission (odds ratio (OR) 0.56, 95% confidence interval (CI) 0.36–0.85) were more likely to progress to AIDS compared with those infected through contaminated blood. Older age at diagnosis of HIV-infected individuals (OR 0.72, 95% CI 0.58–0.89) exhibited a faster progression to AIDS. HIV-infected individuals identified through a unique survey (OR 7.01, 95% CI 2.99–16.44) were less likely to progress to AIDS compared with those identified through medical institutions. HIV-infected individuals who had higher baseline CD4+T cell counts (OR 3.37, 95% CI 2.59–4.38) had a slower progression to AIDS. These findings provide evidence for natural disease progression from HIV to AIDS between TPs and RPs.

COVID-19 serosurvey provides a better estimation of people who have developed antibody against the infection. But limited information on such serosurveys in rural areas poses many hurdles to understand the epidemiology of the virus and to implement proper control strategies. This study was carried out in the rural catchment area of Model Rural Health Research Unit in Odisha, India during March–April 2021, the initial phase of COVID vaccination. A total of 60 village clusters from four study blocks were identified using probability proportionate to size sampling. From each cluster, 60 households and one eligible participant from each household (60 per cluster) were selected for the collection of blood sample and socio-demographic data. The presence of SARS-CoV-2 antibody was tested using the Elecsys Anti-SARS-CoV-2 immunoassay. The overall seroprevalence after adjusting for test performance was 54.21% with an infection to case ratio of 96.89 along with 4.25% partial and 6.79% full immunisation coverage. Highest seroprevalence was observed in the age group of 19–44 years and females had both higher seroprevalence as well as vaccine coverage. People of other backward caste also had higher seropositivity than other caste categories. The study emphasises on continuing surveillance for COVID-19 cases and prioritizing COVID-19 vaccination for susceptible groups for better disease management.

To understand the characteristics and influencing factors related to cluster infections in Jiangsu Province, China, we investigated case reports to explore transmission dynamics and influencing factors of scales of cluster infection. The effectiveness of interventions was assessed by changes in the time-dependent reproductive number (Rt). From 25th January to 29th February, Jiangsu Province reported a total of 134 clusters involving 617 cases. Household clusters accounted for 79.85% of the total. The time interval from onset to report of index cases was 8 days, which was longer than that of secondary cases (4 days) (χ2 = 22.763, P < 0.001) and had a relationship with the number of secondary cases (the correlation coefficient (r) = 0.193, P = 0.040). The average interval from onset to report was different between family cluster cases (4 days) and community cluster cases (7 days) (χ2 = 28.072, P < 0.001). The average time interval from onset to isolation of patients with secondary infection (5 days) was longer than that of patients without secondary infection (3 days) (F = 9.761, P = 0.002). Asymptomatic patients and non-familial clusters had impacts on the size of the clusters. The average reduction in the Rt value in family clusters (26.00%, 0.26 ± 0.22) was lower than that in other clusters (37.00%, 0.37 ± 0.26) (F = 4.400, P = 0.039). Early detection of asymptomatic patients and early reports of non-family clusters can effectively weaken cluster infections.

1. Sera from 500 patients, mostly natives of East Africa, were tested by the Kahn and Wassermann tests, under conditions described.

2. Clinical data were available in the case of 448 specimens. The results of tests upon 230 sera from cases believed to be yaws and syphilis and 218 cases believed not to be yaws and syphilis are discussed. In 46 of the 230 cases, treatment had previously been given.

3. In interpreting results, the resolutions of the League of Nations' Conference on the Serodiagnosis of Syphilis were strictly followed.

4. In the performance of the tests recognised standard methods were used.

5. The two tests correlated exactly in 96·4 per cent. of all cases.

6. The Kahn test was the more sensitive to yaws and syphilis.

7. The Wassermann test alone gave one non-specific reaction.

8. The reagents used in the Kahn test did not deteriorate when kept for two months at room temperature.

9. It is suggested that although the use of both tests is preferable when practicable, the Kahn test alone is a reliable diagnostic measure in the tropics.

Individuals developing an HIV seroconversion illness may experience rapid disease progression. Information on seroconversion illness is rarely collected in most cohort studies; thus the aim of this study was to assess the value of the HIV test interval (the time between last negative and first positive HIV tests) as a proxy for seroconversion illness. Among 8229 seroconverters, test intervals ranged from 0–5282 days, and varied by gender, risk group, age and calendar year of seroconversion. Those with intervals [les ] 31 days had an increased hazard of AIDS (RH 1·42, P = 0·07), which was reduced slightly after adjusting for baseline factors, calendar year of follow-up, treatment and the declining CD4 count, but there was no effect on survival. Thus, it appears that if information on acute seroconversion illness is not available, then analyses of progression to AIDS in seroconverter studies could use a short test interval as a proxy measure.

1. A review of the few studies so far made on the high mortality from tuberculosis among elderly men, and a consideration of the available statistics, indicate that urbanization is one of the principal factors responsible.

2. In the present inquiry, which was confined to London, 445 newly diagnosed cases of tuberculosis in men over 40, together with the same number of paired controls, were studied by means of a questionnaire and of personal interview.

3. It was found that the tuberculous patients differed significantly from the controls in the following characteristics; Scots, Irish, Welsh, or foreign nationality; single, widower or divorced; resident in common lodging houses or hostels; inadequate or special diet; history of gastrectomy; a winter cough; shortness of breath; insufficient sleep; and heavy drinking and smoking. On the other hand, overtime or night work, diabetes, rheumatoid arthritis, asthma, and mental illness were distributed fairly evenly in the two groups.

4. Unfortunately no group of elderly women exists in this country living under the same sort of conditions as the elderly men studied here, so that it was impossible to determine how far the various factors considered were responsible for the high rate of late adult male tuberculosis. A study, however, of a population of established civil servants living under ordinary conditions revealed little difference between the observed rates of tuberculosis and those expected on the basis of national notification figures for men and women in the older age groups.

5. It appears that a low standard of personal hygiene, associated especially with heavy smoking and drinking and residence in loading houses, predispose to the development of tuberculosis in the elderly male. Part of the evil effect of living in common lodging houses in particular may be due to the increased risk of exposure to tuberculous infection that it entails.

6. It is tentatively concluded that the casual workers of an urbanized community are one of the principal reservoirs of tuberculous infection in large towns, and since there is no numerically comparable female population, this group, and its immediate male contacts, account in large measure for the difference between the male and female tuberculosis rates in the older age groups.

This work was initiated during the tenure of a Prophit Scholarship of the Royal College of Physicians, and completed with the aid of a grant from the Medical Research Council.

I am indebted to members of the Prophit Committee of the Royal College of Physicians for their support and encouragement, and most particularly to Dr G. S. Wilson, Director of the Public Health Laboratory Service, under whose guidance the work was carried out. Figures relating to the incidence of tuberculosis in the Civil Service are published by kind permission of Dr W. E. Chiesman, Treasury Medical Adviser, and Dr M. C. W. Long, Dr J. W. Parks, and Dr H. Stannus Stannus, whose departmental records were used to compute the figures.

I am greatly indebted to the consultants and staff of the seventeen chest clinics who co-operated in the investigation, for their interest and help in tracing patients, and to the medical superintendents of numerous sanatoria and chest hospitals, and to the surgeons who permitted me to interview patients under their care as controls.

I should like also to acknowledge the assistance received from the medical officers of health of the metropolitan boroughs who kept me informed of notifications from lodging houses in their areas, and supplied information about the accommodation.

At the present time owing to the difficulties arising from was conditions, and the stress of work due to the special circumstances in which the study of bacteriology is being prosecuted, we have had in some cases to modify established methods of bacteriological procedure and introduce new technique.

An investigation into the probable influence of environmental factors on the incidence of extrapulmonary tuberculous infections and into the possible explanation of their effect on regional differences in the proportional frequency of the type of infecting strain of the tubercle bacillus has been described.

The importance of substandard housing and of family history in infection with the human type of the tubercle bacillus, particularly in children, has been noted.

Circumstantial evidence of both low economic resources and milk supply influencing infection with the bovine type of the tubercle bacillus pointed to these factors being important in childhood.

I wish to acknowledge the co-operation I received from the Medical Officers of Health for the several Local Authorities within the county of Lanark.