H9 avian influenza virus played a key role during generation of the novel H7N9 virus. A surveillance programme was conducted to assess the H9 virus in relation to the risk of H7N9 virus contamination in the environment. Risk of H7N9 virus contamination in the presence of H9 virus was higher than without (adjusted odds ratio 4·49, 95% confidence interval 3·79–5·31). Adjusted odds ratios of the H7N9 virus associated with co-presence of H9 virus and interacting factors were 4·93 (rural vs. urban area), 46·80 (live poultry markets vs. other premises), 6·86 (Huzhou vs. Hangzhou prefecture), 40·67 (year 2015 vs. 2013), and 9·63 (sewage from cleaning poultry vs. poultry faeces). Regular surveillance on gene variability of H7N9 and H9 viruses should be conducted and extra measures are needed to reduce co-circulation of H7N9 and H9 viruses in the environment.

Shiga-toxin producing Escherichia coli (STEC) is a pathogen that can cause bloody diarrhoea and severe complications. Cases occur sporadically but outbreaks are also common. Understanding the incubation period distribution and factors influencing it will help in the investigation of exposures and consequent disease control. We extracted individual patient data for STEC cases associated with outbreaks with a known source of exposure in England and Wales. The incubation period was derived and cases were described according to patient and outbreak characteristics. We tested for heterogeneity in reported incubation period between outbreaks and described the pattern of heterogeneity. We employed a multi-level regression model to examine the relationship between patient characteristics such as age, gender and reported symptoms; and outbreak characteristics such as mode of transmission with the incubation period. A total of 205 cases from 41 outbreaks were included in the study, of which 64 cases (31%) were from a single outbreak. The median incubation period was 4 days. Cases reporting bloody diarrhoea reported shorter incubation periods compared with cases without bloody diarrhoea, and likewise, cases aged between 40 and 59 years reported shorter incubation period compared with other age groups. It is recommended that public health officials consider the characteristics of cases involved in an outbreak in order to inform the outbreak investigation and the period of exposure to be investigated.

1. Thirty-four vaginal Corynebacteria have been grouped and subgrouped according to their cultural and biochemical characters. Owing to their instability and to the rigid taxonomy of the Corynebacteria, the exact identity of many of the strains is uncertain, but their characters have been compared with some of the Corynebacteria which have been given specific rank.

2. The majority of strains were carbohydrate-fermenters and many were of the hyperacid type. These may be associated in some way with a normal high vaginal acidity.

3. Many instances of resemblances to C. diphtheriae in morphology, in staining reactions, and in cultural appearances relating to the different dissociative phases, were encountered in the examination of these strains, and, in fact, some of the cultural types seen were analogous to those of C. diphtheriae described by Mcleod.

4. Intradermal tests on rabbits showed that many of these strains, including some from each group, were capable of inciting inflammatory reactions in their tissues, and it is suggested that they may play a secondary part in some infections.

Syndromic surveillance was originally developed to provide early warning compared to laboratory surveillance, but it is increasing used for real-time situational awareness. When a potential threat to public health is identified, a rapid assessment of its impact is required for public health management. When threats are localised, analysis is more complex as local trends need to be separated from national trends and differences compared to unaffected areas may be due to confounding factors such as deprivation or age distributions. Accounting for confounding factors usually requires an in-depth study, which takes time. Therefore, a tool is required which can provide a rapid estimate of local incidents using syndromic surveillance data.

Here, we present ‘DiD IT?’, a new investigation tool designed to measure the impact of local threats to public health. ‘DiD IT?’ uses a difference-in-differences statistical approach to account for temporal and spatial confounding and provide a direct estimate of impact due to incidents. Temporal confounding differences are estimated by comparing unaffected locations during and outside of exposure periods. Whilst spatial confounding differences are estimated by comparing unaffected and exposed locations outside of the exposure period. Any remaining differences can be considered to be the direct effect of the local incident.

We illustrate the potential utility of the tool through four examples of localised health protection incidents in England. The examples cover a range of data sources including general practitioner (GP) consultations, emergency department (ED) attendances and a telehealth call and online health symptom checker; and different types of incidents including, infectious disease outbreak, mass-gathering, extreme weather and an industrial fire. The examples use the UK Health Security Agency's ongoing real-time syndromic surveillance systems to show how results can be obtained in near real-time.

The tool identified 700 additional online difficulty breathing assessments associated with a severe thunderstorm, 53 additional GP consultations during a mumps outbreak, 2–3 telehealth line calls following an industrial fire and that there was no significant increase in ED attendances during the G7 summit in 2021.

DiD IT? can provide estimates for the direct impact of localised events in real-time as part of a syndromic surveillance system. Thus, it has the potential for enhancing surveillance and can be used to evaluate the effectiveness of extending national surveillance to a more granular local surveillance.

Applying a method of selective separation of the specific high polymers the intracellular site of the specific substance in the Copenhagen strain of Pneumococcus Type II was demonstrated, by electron microscopy; the specific polymeric material assumed to form the capsule is situated within the bacterial cell and the electron density of this material is sufficiently high to permit its detection.

The possibility of obtaining electron micrographs of the polymeric substances as contained in the cells or after their diffusion into the medium or when secreted as slime, suggests that the current concept of the capsules as the site of the specific substances may have to be reviewed.

The electron micrographs were made by Dr A. Petrovici to whom I express my thanks.

It is unclear if – after symptom onset of a primary case of coronavirus disease-2019 (COVID-19) in a household – ensuing chains of transmissions among household members occur and if household epidemiology of COVID-19 is modified by the different circulating variants. We analysed data of 52 774 household clusters to investigate the day of symptom onset of ensuing cases in households relative to the symptom onset of the primary case within the household. Irrespective of cluster size or age of the primary case, 95% of all secondary household cases had symptom onset within 14 days after the symptom onset of the primary case. Stratification by variant showed that the mean interval from symptom onset of the primary case to the symptom onset of secondary cases decreased significantly from 4.8 days (wildtype) to 4.5 days (alpha) and 4.0 days (delta). Similarly, the cumulative proportion of 95% of secondary cases occurred within 14 days (wild type), 12 days (alpha) and 10 days (delta). Our findings suggest that during dominant delta circulation – apart from rare individual constellations – a 10-day household quarantine after symptom onset of the primary case is sufficient for household contacts who remain COVID-free.

Ross River virus (RRV), the most medically and economically important arbovirus in Australia, has been the most prevalent arbovirus infections in humans for many years. Infected humans and horses often suffer similar clinical symptoms. We conducted a prospective longitudinal study over a 3.5-year period to investigate the exposure dynamics of RRV in three foal cohorts (n = 32) born in a subtropical region of South East Queensland, Australia, between 2020 and 2022. RRV-specific seroconversion was detected in 56% (n = 18) of foals with a median time to seroconversion, after waning of maternal antibodies, of 429 days (95% CI: 294–582). The median age at seroconversion was 69 weeks (95% CI: 53–57). Seroconversion events were only detected between December and March (Southern Hemisphere summer) over the entire study period. Cox proportion hazards regression analyses revealed that seroconversions were significantly (p < 0.05) associated with air temperature in the month of seroconversion. Time-lags in meteorological variables were not significantly (p > 0.05) associated with seroconversion, except for relative humidity (p = 0.036 at 2-month time-lag). This is in contrast to research results of RRV infection in humans, which peaked between March and May (Autumn) and with a 0–3 month time-lag for various meteorological risk factors. Therefore, horses may be suitable sentinels for monitoring active arbovirus circulation and could be used for early arbovirus outbreak detection in human populations.

The aim of this study was to explore the impact of polymorphism of PD-1 gene and its interaction with tea drinking on susceptibility to tuberculosis (TB). A total of 503 patients with TB and 494 controls were enrolled in this case–control study. Three single-nucleotide polymorphisms of PD-1 (rs7568402, rs2227982 and rs36084323) were genotyped and unconditional logistic regression analysis was used to identify the association between PD-1 polymorphism and TB, while marginal structural linear odds models were used to estimate the interactions. Genotypes GA (OR 1.434), AA (OR 1.891) and GA + AA (OR 1.493) at rs7568402 were more prevalent in the TB patients than in the controls (P < 0.05). The relative excess risk of interaction (RERI) between rs7568402 of PD-1 genes and tea drinking was −0.3856 (95% confidence interval −0.7920 to −0.0209, P < 0.05), which showed a negative interaction. However, the RERIs between tea drinking and both rs2227982 and rs36084323 of PD-1 genes were not statistically significant. Our data demonstrate that rs7568402 of PD-1 genes was associated with susceptibility to TB, and there was a significant negative interaction between rs7568402 and tea drinking. Therefore, preventive measures through promoting the consumption of tea should be emphasised in the high-risk populations.

The sera of 200 Chinese adults recently immigrated to Canada from Hong Kong were examined for antibodies to Toxoplasma gondii by the indirect fluorescent antibody technique. It was found that the total incidence was 18·0%. This is significantly lower than that of the indigenous population of the same age groups in this area.

Skin tests made with the toxin obtained from Tunnicliff's strain of green producing streptococcus on normal individuals, and on cases prior to and after an attack of measles did not give any definite positive evidence of the etiological relationship of this organism to measles. Further, an attack of measles did not produce any apparent increase in the antitoxic content of a patient's serum for this toxin.

The sensitivity of in vitro- and in vivo-grown strains of S. typhi was determined not only by their antigenic structure, but also by their growth phase. An increased vulnerability to the antibody-complement system has been found in cells during the lag and the early exponential phase, while non-multiplying cells devoid of any nutrient were almost invulnerable to the antibody-complement system. Extracts of organs from normal and infected animals may promote the growth of S. typhi, and, therefore, increase its vulnerability to the antibody-complement system. The majority of extracts from organs of mice infected with strain Ty 2 inhibited markedly the bactericidal action of serum on this strain and, to a lower extent, on strain O 901.

It is well known that removal of the pituitary gland is followed by alterations in a number of metabolic processes. It was therefore thought of interest to determine whether these alterations involved any changes in certain immune processes, since very little is known at present of the factors controlling them. Our immunity experiments were made on rabbits and consisted in determining the complement content, the bactericidal power and the opsonic activity of the rabbits' serum.

We have heard much in recent times of the decrease of tuberculosis and of the increase in mortality from cancer. I propose on the basis of data from some great cities and other areas of the German-speaking world to ascertain whether, if attention is paid to age distribution, cancer really presents so striking a contrast with other causes of mortality. With a view to solving the problem let us enquire whether the undoubted absolute increase may not be a mere function of the ageing of the population, a feature common to all civilised countries. Most weight will be placed upon the statistical data derived from cities because of the greater reliability of the diagnoses in hospitals, and because, as a rule, the death certificate is filled up by the practitioner who actually attended the patient.

The authors have determined the vitamin A content of the liver in persons who had succumbed to sudden death in Copenhagen in 1939 and 1943 and in Oslo in 1943–4. The values in Oslo after three years of war and severe rationing were higher than in Copenhagen, the population of which had a much milder rationing during the war. The values in Copenhagen for 1943 were somewhat lower than those for 1939. The most plausible explanation of these findings seems to be that the pre-war vitamin A reserve in Norway was high.

The various problems of infantile mortality are not only supremely interesting to the medical officer of health, but, with the continued decline in the birth rate, are calculated to assume even greater practical importance in the birth rate, are calculated to assume even greater practical importace in the near future. Of these problems none is more in need of solution than the exact etiology of infantile diarrhoea.

1. The participation times of a series of mixtures of horse serum and a pool of rabbit antihorse serum have been determined. The results have been presented in a table and isochrones drawn. Four distinct α procedure optima were found, suggesting that there may be at least four different antigen-antibody reactions concerned when horse serum reacts with a rabbit antihorse serum.

2. The reaction between horse serum crystalbumin and the same pooled rabbit antihorse serum has been investigated, and recorded-similarly.

3. Inhibition of precipitation was found to be more marked in the region of antigen excess than in the region of antiserum excess. Evidence is presented in support of the view that the occurrence of multiple zones may obscure this observation.

4. The results are compatible with the view that the second stage of the precipitation reaction is specific.

5. The isochrones correspond with Boyd's R type.

1. One hundred lepers were examined by Browning, Cruickshank and McKenzie's modification of the Wassermann reaction with positive results in 22 cases. The amount of complement deviated was in some cases exceptionally large.

2. In a control group of 110 non-leprous persons there were 11 positive reactions.

3. In only one of the lepers was there visible evidence of former venereal disease but 33 of the lepers admitted that they had suffered from syphilis or from chancres, and of these 33, 13 reacted positively, while only nine of the remaining 66 gave positive reactions.

4. In the control group, 21 admitted former syphilitic infection and, of these, eight reacted positively; among the remaining 89, who denied syphilis, there were three positive reactions.

5. There were 12 positive reactions among 44 cases of tubercular leprosy and 10 positive reactions among 56 cases of the anaesthetic type.

6. The average duration of the disease, among the 22 lepers who reacted positively, was four years and eight months, as compared with an average of three years and eight months for the 78 patients who reacted negatively; but among the latter there were many old-standing cases.

7. Seventeen of the 22 positive cases were in an advanced stage of leprosy and in some of them the disease was progressing; but among those lepers who reacted negatively there were also many advanced and progressing cases.

8. Serum from the lesions in 10 of the lepers who reacted positively was examined by dark-ground illumination, but in no case was the Treponema pallidum found.

9. The luetin test was applied to 21 lepers, with negative results in every instance; 13 of these cases gave positive and eight gave negative Wassermann reactions. The test was also applied to a control group of non-leprous persons selected because they were likely to be latent syphilitics. In this group there were 11 positive luetin reactions.

“Health is more affected by atmospheric conditions than by any other influence. From the moment the new born child utters its first cry, until life finally ceases, he is directly and immediately dependent on the atmosphere he breathes for continued existence. Records of sickness and of mortality clearly show that the nearer atmospheric conditions are to those of the open country, the better is the health of the population, and that the more these conditions are modified owing to urbanisation and industrialisation, the more pronounced is the ill-effect upon general health” (1).