Different countries have adopted strategies for the early detection of SARS-CoV-2 since the declaration of community transmission by the World Health Organization (WHO) and timely diagnosis has been considered one of the major obstacles for surveillance and healthcare. Here, we report the increase of the number of laboratories to COVID-19 diagnosis in Brazil. Our results demonstrate an increase and decentralisation of certified laboratories, which does not match the much higher increase in the number of COVID-19 cases. Also, it becomes clear that laboratories are irregularly distributed over the country, with a concentration in the most developed state, São Paulo.

In my first report I showed that in the throats of persons not known to have been in contact with cases of cerebro-spinal fever organisms were frequently found which were indistinguishable from meningococci isolated from the cerebro-spinal fluid of persons suffering from that disease.

To assess the relationship between the neutrophil-to-lymphocyte ratio (NLR) and related parameters to the severity of coronavirus disease 2019 (COVID-19) symptoms. Clinical data from 38 COVID-19 patients who were diagnosed, treated and discharged from the Qishan Hospital in Yantai over the period from January to February 2020 were analysed. NLR and procalcitonin (PCT) were determined in the first and fourth weeks after their admission, along with the clinical characteristics and laboratory test results of these patients. Based on results as obtained on the first and fourth weeks after admission, five indices consisting of NLR, white blood cells, neutrophils, lymphocytes (LY) and monocytes (MON) were selected to generate receiver operating characteristic curves, while optimal cutoff values, sensitivities and specificities were obtained according to the Yuden index. Statistically significant differences in neutrophils, LY and the NLR were present in the severe vs. moderate COVID-19 group from the first to the fourth week of their hospitalisation. The cut-off value of NLR for predicting the severity of COVID-19 was 4.425, with a sensitivity of 0.855 and a specificity of 0.979. A statistically significant positive correlation was present between PCT and NLR in the severe group as determined within the first week of admission. NLR can serve as a predictor of COVID-19 disease severity as patients' progress from the first to the fourth week of their hospitalisation. The statistically significant positive correlation between levels of NLR and PCT in severe patients indicated that increases in NLR were accompanied with gradual increases in PCT.

1. The virulence of a given strain of B. aertrycke was tested on 54 occasions during the 3-year period, October 1926–October 1929. Each test was made by inoculating intra-peritoneally about 100 viable organisms into 20 parti-coloured mice, usually of 17–23 grm. in weight, drawn at random from the general laboratory stock. The average number of specific deaths caused by this procedure was 12·71 ± 3·39, but very marked deviations were noticeable, varying from a minimum of 5 to a maximum of 20. These deviations occurred without any observable regularity, and appeared to have no definite seasonal relationship. Evidence is brought to suggest that they were chiefly determined not by variations in the dosage or in the virulence of the strain, but by fluctuations in the resistance of the mice.

2. The meaning of the term “resistance” is discussed, and it is suggested that the term “fluctuating immunity” should be used to denote those variations in resistance which occur from time to time, and which are due to alterations in the physiological behaviour of the animal dependent on changing environmental conditions. This fluctuating immunity should be distinguished from innate, inherited, orgenetic immunity on the one hand and from acquired immunity on the other.

3. It is pointed out that the existence of fluctuations from time to time in the susceptibility of animals to infection renders fruitless any attempt to obtain an absolute measure of virulence. The most that can be done is to compare the relative virulence of two or more strains injected simultaneously.

A total of 160 consecutive isolates of Neisseria gonorrhoeae was collected over a 3-month period. They were tested for their susceptibility to penicillin, erythromycin and spectinomycin and the auxotype and the serotype determined. We have evaluated two sampling methods, the collection of every fifth isolate and the first 20 isolates (10 male and 10 female) each month, to determine whether either is representative of the total population. There was no significant difference between either method of sampling and the total for detecting the predominant auxotypes and serovars or the distributions in antibiotic susceptibility. It is possible to monitor major changes in a gonococcal population, particularly susceptibility to antibiotics, using a sample of the total population.

Considerable difference of opinion has existed as to whether the incidence of cancer is at all affected by the habits of life of different classes of the community. There is of course no doubt that in certain occupations particular forms of malignant disease are exceptionally prevalent, the case of chimney sweeps being notorious; but the more general question as to the incidence on large groups of occupations has not been so definitely determined. The present research was suggested by the apparently contradictory results obtained by Heron from his study of London statistics, and by Maynard from an analysis of United States data.

Estimates of the proportion of illness transmitted by food for different enteric pathogens are essential for foodborne burden-of-disease studies. Owing to insufficient scientific data, a formal synthesis of expert opinion, an expert elicitation, is commonly used to produce such estimates. Eleven experts participated in an elicitation to estimate the proportion of illnesses due to food in Australia for nine pathogens over three rounds: first, based on their own knowledge alone; second, after being provided with systematic reviews of the literature and Australian data; and finally, at a workshop where experts reflected on the evidence. Estimates changed significantly across the three rounds (P = 0·002) as measured by analysis of variance. Following the workshop in round 3, estimates showed smoother distributions with significantly less variation for several pathogens. When estimates were combined to provide combined distributions for each pathogen, the width of these combined distributions reflected experts’ perceptions of the availability of evidence, with narrower intervals for pathogens for which evidence was judged to be strongest. Our findings show that the choice of expert elicitation process can significantly influence final estimates. Our structured process – and the workshop in particular – produced robust estimates and distributions appropriate for inclusion in burden-of-disease studies.

We investigated an outbreak of norovirus that affected students and teachers of a high school in Lleida, Spain through various transmission mechanisms. A case-control epidemiological study of the risk of disease and the relative importance of each mode of transmission was carried out. Cases and controls were selected from a systematic sample of students and teachers present at the school on 28 January. Faecal samples were taken from three food handlers and 16 cases. The influence of each factor was studied using the adjusted odds ratio (aOR) and the estimated population attributable risk (ePAR) with 95% confidence intervals (CI). We interviewed 210 people (42 cases, 168 controls). The proportion of symptoms in these individuals was nausea 78·6%, vomiting 59·5%, diarrhoea 45·2%, and fever 19·0%. The epidemic curve showed transmission for at least 4 days. The risk of disease was associated with exposure to food (aOR 5·8) in 66·1% of cases and vomit (aOR 4·7) in 24·8% of cases. Faecal samples from 11 patients and two food handlers were positive for norovirus GII.12 g. Vomit may co-exist with other modes of transmission in norovirus outbreaks and could explain a large number of cases.

Hides and calf skins cured with marine salts, especially if kept under conditions of warmth and moisture, tend to develop on the flesh side large areas of brick-red coloration. Similar red colorations have, for many years, been noted as occurring in similar conditions on salted fish, and a number of investigations have been made as to their cause, the first recorded being that of Farlow (1878). Following him were Mauriac (1886), Ewart (1887), Layet (1887), Le Dantec (1891) and, in recent years, Harrison and Kennedy (1922), Browne (1921–22) and Cloake (1923). All these workers have agreed in attributing the red coloration on salted fish to the growth of one or several species of redcoloured organisms, and the more recent workers (Harrison and Kennedy, Browne, Cloake) trace these organisms to the sea salt used in curing the fish, and find them to be chromogenic bacteria only capable of growth in a high concentration of salt. Clayton and Gibbs (1927) have examined many solar brines and salts, and have found that “they almost invariably contain microorganisms which only exist and develop in the presence of abundance of common salt.” Sturges and Heidemann (1923, 1924) have isolated many saltloving organisms from meat-curing solutions, and Le Fèvre and Round (1919) from the brine of pickled cucumber.

1. In two areas in the Eastern Counties, Cambridge and Norwich, naso-pharyngeal swabs were taken from 400 individuals, who represented different conditions of health and social circumstances.

The investigation was made at Cambridge between the months of June and October, 1916, and at Norwich during August, 1916.

Owing to the low incidence of cerebro-spinal fever in the two towns during the year 1916 (see p. 249), the general population may be regarded as practically “non-contact” in respect of this disease.

2. As a result of the investigation, strains giving all the cultural and microscopical tests of the meningococcus were obtained as follows:

(a) From 200 swabs taken at Addenbrooke's Hospital during June and July, 1917, mostly from normal people, 30 strains.

(b) From 100 swabs taken at the Norfolk and Norwich Hospital during August, from individuals mostly in impaired health, 27 strains.

(c) From 100 swabs taken in Cambridge during October, from factory employees, who were all in good health and mostly in comfortable circumstances, 37 strains.

3. Such strains were found more often in males of every age group than in females, and in adults more often than in children.

In regard to the influence of health and surroundings, the results of the investigation grouped together show a larger proportion amongst town dwellers than amongst country people and amongst people with impaired health than amongst the healthy.

General conclusions cannot, however, be drawn from these figures because conditions were not always comparable. For instance, the majority of country people were examined in June and July, when positive findings were low.

In examining the employees at a factory, I obtained the strains in a higher proportion from the men working in those shops where air space was more restricted and ventilation less perfectly effected.

4. The 94 strains collected from 400 naso-pharyngeal swabs were tested as regards their agglutinability against certain monovalent sera. These sera were prepared from seven strains of meningococci of cerebrospinal orgin, and from two of the naso-pharyngeal cocci which had been isolated during the course of the investigation. The meningococcal strains used for preparing the sera included strains which had been found identical with others occurring with considerable frequency in cerebrospinal fluid and capable of being grouped in two main groups; they also included strains which differed from these and were apparently rarer; but there is no reason to assume that every variety occurring in the specific disease was represented.

The results of the tests on the above 94 strains may be classified as follows:

(a) 22 gave no agglutination above 1: 100 with any of the sera used.

(b) Two agglutinated well with certain sera, but also agglutinated with normal rabbit serum.

(c) 31 agglutinated up to 1–200 or 1–400 with the sera of a certain group (M I–M IV), and in some instances gave similar agglutination with other sera not belonging to this group.

(d) 39 agglutinated with the sera of the group M I–M IV to the full titre of the homologous strains, while with the sera belonging to other groups good agglutination was not often obtained.

This last group of 39 strains (41 per cent. of all tested) appears to be indistinguishable by simple agglutination tests from the M I–M IV group of cerebro-spinal meningococci. The previous group of 31 (33 per cent. of all tested) shows evidence of serological relationship with meningococci of cerebro-spinal origin, but it is not possible on their agglutination tests alone to give an opinion as to their identity with any meningococcal group.

Agglutination tests as a whole indicated that about 74 per cent. of strains collected on account of their resemblance to the meningococcus in culture, gave evidence of relationship to the meningococcus in virtue of their agglutination reactions with anti-meningococcal sera.

5. In order to determine if the absorption test would corroborate the relationship shown by agglutination, absorption tests were done against a serum prepared by inoculation of a cerebro-spinal strain of meningococcus, M I, with all the strains, culturally and by simple agglutination indistinguishable from pathogenic meningococci, which had been collected from the last 100 swabs (normal factory employees, Cambridge). Nine absorbed the agglutinin as well as the homologous coccus and four absorbed it partially.

Therefore, out of 100 normal people who had not been in contact with a case of cerebro-spinal fever, 9 per cent. were shown to be harbouring organisms in their naso-pharynx which were serologically identical with meningococci of pathological origin (cerebro-spinal fluid) and, in addition, 4 per cent., making 13 per cent. in all, were so closely allied as to be doubtfully distinguishable even by the test for absorption of agglutinin.

Similar results were obtained with strains obtained from Norwich.

The above results were confirmed by testing absorption by these cocci from another serum prepared with another spinal strain of meningococcus possessing properties almost identical with M I. I have not investigated absorption with sera prepared with strains which differ serologically from M I.

6. With regard to those naso-pharyngeal strains which were not identified with cerebro-spinal strains by serological tests (agglutination and absorption), I consider that in view of the great variation in the serological reactions shown by different strains of undoubted meningococci and even by different emulsions of the same strain, it is very difficult, if not impossible, to exclude any such microscopically and culturally typical organisms from the meningococcus group on the basis of serological tests.

1. The effect of either or both caloric and protein deficiency on the susceptibility of rats and mice to peroral infection with Salmonella typhi murium was studied.

2. Moderate restriction of food intake (80% of normal diet) for a period of 5 weeks was without influence on the infection susceptibility of rats, even when the diet fed was low in protein.

3. Long-term restriction of food intake (10 weeks) led to a marked lowering of the resistance of rats to the infection, there being a direct relation between the magnitude of the intake restriction and the extent of the resulting loss of resistance.

4. The infection resistance of rats was lowered more markedly by a given total restriction of food intake, when the latter was imposed in the form of a gradually reduced ration, than when it was imposed in a uniformly restricted ration. The effect so produced was independent of the protein content of the diet.

5. The effect of gradual food restriction was diminished by gradual supplementation of the diet with non-proteins and was augmented by gradual supplementation of the same diet with protein.

6. In mice kept on a restricted diet loss of resistance to S. typhi murium has been shown to be due to a deficiency of both calories and protein.

In the examination of bovine fetal material it was found that there was a significant increase in the proportion of mixed infections identified as the time between abortion and the collection of the samples increased. Examination of paired serum samples from abortions from which only Corynebacterium pyogenes was isolated revealed evidence of active infection in two-thirds, suggesting that C. pyogenes may have been acting as a primary abortifacient in these cases.

We recently described a simple model through which we assessed what effect subjecting travellers to a single on-arrival test might have on reducing risk of importing disease cases during simulated outbreaks of coronavirus disease 2019 (COVID-19), influenza, severe acute respiratory syndrome (SARS) and Ebola. We build upon this work to allow for the additional requirement that inbound travellers also undergo a period of self-isolation upon arrival, where upon completion the traveller is again tested for signs of infection prior to admission across the border. Prior results indicated that a single on-arrival test has the potential to detect 9% of travellers infected with COVID-19, compared to 35%, 10% and 3% for travellers infected with influenza, SARS and Ebola, respectively. Our extended model shows that testing administered after a 2-day isolation period could detect up to 41%, 97%, 44% and 15% of COVID-19, influenza, SARS and Ebola infected travellers, respectively. Longer self-isolation periods increase detection rates further, with an 8-day self-isolation period suggesting detection rates of up to 94%, 100%, 98% and 62% for travellers infected with COVID-19, influenza, SARS and Ebola, respectively. These results therefore suggest that testing arrivals after an enforced period of self-isolation may present a reasonable method of protecting against case importation during international outbreaks.

The outer membrane proteins of 38 Yersinia pestis isolates from all known plague foci of north-east Brazil were analysed by SDS-PAGE. Approximately 20 bands were consistently found in all strains analysed and 11 were selected for comparative studies. Although qualitative differences among the electrophoretic profiles of outer membrane proteins of wild Y. pestis isolates were not observed, quantitative alterations were clearly noted for most of these proteins. No particular quantitative alteration of the electrophoretic profile of outer membrane proteins could be associated with the period of isolation and geographic origin of the isolates. The 64 kDa outer membrane protein was significantly expressed in higher amounts among Y. pestis strains isolated from a recent plague outbreak. The possible use of electrophoretic profiles of outer membrane proteins of wild Y. pestis isolates as a tool for epidemiological studies and for the analysis of virulence determinants is discussed.

Infectious diseases remain one of the leading causes of death worldwide. The aim of this descriptive epidemiological study was to analyse the trends in mortality from infectious diseases in Serbia (excluding the Autonomous Province of Kosovo & Metohia) from 1991 to 2014 using joinpoint regression analysis. The mortality rates from infectious diseases were found to have increased markedly from 1991 to 1994 (+12·4% per year), followed by a significant decline from 1994 to 2009 (–4·6% per year) and then another increase from 2009 to 2014 (+4·3% per year). Throughout the study period, mortality rates were consistently higher in men than in women. Although a substantial decline was observed for young people of both sexes, no consistent pattern was evident for the middle-aged nor the elderly. Since 1991, septicaemia has emerged as a leading cause of infectious disease mortality, particularly in older men. The Yugoslav civil wars in the 1990s and the global financial crisis in 2008 corresponded with changes in the trends in mortality from infectious diseases in Serbia, with the elderly showing particular vulnerability during those time periods. Data presented in this study might be useful to improve control of infectious diseases in Serbia.

Immunization procedures with live attenuated and inactivated vaccines were carried out on a group of young recruits at the beginning of an outbreak of infection due to an A/Victoria/3/75-related virus strain, which occurred in February 1977 in a military camp. A retrospective investigation on protection from clinical influenza was then performed in order to investigate whether immunization with live virus vaccines, administered at the beginning of an epidemic, could provide early protection from the disease. In the course of the two weeks following vaccination, laboratory-confirmed clinical influenza cases occurred in 4 subjects among the 110 volunteers of the control group which received placebo, and in 8, 7 and 4 subjects respectively of the 3 groups of about 125 individuals, each of which received one of the following vaccine preparations: (a), live attenuated A/Victoria/3/75 influenza virus oral vaccine, grown on chick embryo kidney culture; (b), live attenuated nasal vaccine, a recombinant of A/Puerto Rico/8/34 with A/Victoria/3/75 virus; and (c), inactivated A/Victoria/3/75 virus intramuscular vaccine. These data do not support the hypothesis that, during an epidemic of infection, early protection from clinical influenza can be achieved through immunization with live attenuated or inactivated influenza virus vaccines, in spite of the high immunizing capability of the vaccine preparations.

Seasonal influenza is a significant public health concern globally. While influenza vaccines are the single most effective intervention to reduce influenza morbidity and mortality, there is considerable debate surrounding the merits and consequences of repeated seasonal vaccination. Here, we describe a two-season influenza epidemic contact network model and use it to demonstrate that increasing the level of continuity in vaccination across seasons reduces the burden on public health. We show that revaccination reduces the influenza attack rate not only because it reduces the overall number of susceptible individuals, but also because it better protects highly connected individuals, who would otherwise make a disproportionately large contribution to influenza transmission. We also demonstrate that our results hold on an empirical contact network, in the presence of assortativity in vaccination status, and are robust for a range of vaccine coverage and efficacy levels. Our work contributes a population-level perspective to debates about the merits of repeated influenza vaccination and advocates for public health policy to incorporate individual vaccine histories.

In individuals with latent tuberculosis (TB) infection, those living with human immunodeficiency virus (HIV) had a 20–37 times higher risk of developing active TB compared to those without HIV infection. Systematic testing and treatment of latent TB infection are priorities in HIV-infected persons. In China, the prevalence of HIV infection in men who have sex with men (MSM) has gradually increased in the past decade. However, the prevalence of TB infection has been studied sparsely in HIV-infected MSM. Hence, we conducted a pilot study in MSM living with HIV infection in Xi'an city to evaluate TB infection status by means of interferon-γ release assay (IGRA). A total of 182 HIV-infected MSM were included in this study, the prevalence of IGRA positivity was observed to be 8·79% (16/182). IGRA quantitative results were not statistically influenced by the CD4 cell counts of the study participants. However, IGRA positivity was found to be lower than our previously reported data from the general population. This suggests that immunological deficiency might decrease the sensitivity of IGRA and thus increase the number of false negatives. Our primary results, suggesting systematic testing and treatment of latent TB infection together with active case-finding, were equally important for TB control in persons living with HIV infection.