Laboratory tests were carried out to assess the efficacy of gophacide as a rodenticide against the Norway rat (Rattus norvegicus) and the house mouse (Mus musculus). Results of feeding tests with wild animals suggest that the compound would be more useful against mice than rats, and that 0.3% would be a near optimal concentration for field trials for both species.

The hazards of using gophacide as a rodenticide are discussed.

Few countries routinely collect comprehensive encephalitis data, yet understanding the epidemiology of this condition has value for clinical management, detecting novel and emerging pathogens, and guiding timely public health interventions. When this study was conducted there was no standardized diagnostic algorithm to aid identification of encephalitis or systematic surveillance for adult encephalitis. In July 2012 we tested three pragmatic surveillance options aimed at identifying possible adult encephalitis cases admitted to a major Australian hospital: hospital admissions searches, clinician notifications and laboratory test alerts (CSF herpes simplex virus requests). Eligible cases underwent structured laboratory investigation and a specialist panel arbitrated on the final diagnosis. One hundred and thirteen patients were initially recruited into the 10-month study; 20/113 (18%) met the study case definition, seven were diagnosed with infectious or immune-mediated encephalitis and the remainder were assigned alternative diagnoses. The laboratory alert identified 90% (102/113) of recruited cases including six of the seven cases of confirmed encephalitis suggesting that this may be a practical data source for case ascertainment. The application of a standardized diagnostic algorithm and specialist review by an expert clinical panel aided diagnosis of patients with encephalitis.

We aimed to study patterns of shigellosis in a large observant Jewish community in Israel and to describe local interventions during outbreaks. Surveillance data from the Ministry of Health were used to calculate incidence rates in 1998–2006, both in the city of Bene Beraq and the Tel Aviv district. Information on isolates was collected from the bacteriological laboratory of a community hospital. Public notices and educational conferences conveyed a message to increase personal hygiene and keep ill children at home. During a 9-year period, a clear biennial pattern of outbreaks was noticed. Annual incidence rates ranged between 18 and 353/100 000 population. Shigellosis outbreaks tended to occur in the winter and were attributed to clonally related Shigella sonnei strains. Outbreaks in Bene Beraq preceded those in the other cities of Tel Aviv district, suggesting propagation of disease. In this population with highly endemic as well as superimposed outbreaks of shigellosis, short-term interventions had no lasting effect on prevention; future studies should focus on community-based programmes to avoid anticipated outbreaks.

Burden of bacteraemia is rising due to increased average life expectancy in developed countries. This study aimed to compare the epidemiology and outcomes of bacteraemia in two similarly ageing populations with different ethnicities in Singapore and Denmark. Historical cohorts from the second largest acute-care hospital in Singapore and in the hospitals of two Danish regions included patients aged 15 and above who were admitted from 1 January 2006 to 31 December 2016 with at least 1 day of hospital stay and a pathogenic organism identified. Among 13 144 and 39 073 bacteraemia patients from Singapore and Denmark, similar 30-day mortality rates (16.5%; 20.3%), length of hospital stay (median 14 (IQR: 9–28) days; 11 (6–21)), and admission rate to ICU (15.5%; 15.6%) were observed, respectively. Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus ranked among the top four in both countries. However, Singaporeans had a higher proportion of patients with diabetes (46.8%) and renal disease (29.5%) than the Danes (28.0% and 13.7%, respectively), whilst the Danes had a higher proportion of patients with chronic pulmonary disease (18.0%) and malignancy (35.3%) than Singaporeans (9.7% and 16.2%, respectively). Our study showed that top four causative organisms and clinical outcomes were similar between the two cohorts despite pre-existing comorbidities differed.

The 2014 Ebola epidemic was the largest on record. It evidenced the need for improved models of the spread of Ebola. In this research we focus on modelling Ebola within a small village or community. Specifically, we investigate the potential of basic Susceptible-Exposed-Infectious-Recovered (SEIR) models to describe the initial Ebola outbreak, which occurred in Meliandou, Guinea. Data from the World Health Organization is used to compare the accuracy of various models in order to select the most accurate models of transmission and disease-induced responses. Our results suggest that (i) density-dependent transmission and mortality-induced behavioural changes shaped the course of the Ebola epidemic in Meliandou, while (ii) frequency-dependent transmission, disease-induced emigration, and infection-induced behavioural changes are not consistent with the data from this epidemic.

Environmental samples are considered to be a cost-effective method of identifying Mycobacterium avium subsp. paratuberculosis (MAP)-positive dairy herds, but evidence for beef cow-calf herds is weak. This study aims at evaluating this approach in a total of 20 German herds that were characterized by individual faecal samples (n = 2545) of all cows. For 14 MAP-positive herds having at least one MAP-positive animal, the within-herd prevalence was calculated from concurrent individual faecal culture-based testing. Six herds certified as ‘MAP free’ based on the negative results of previous years served as MAP-negative controls. On average, six environmental samples were taken at the end of winter from areas with high cow traffic and tested for MAP by faecal culture. According to the environmental samples, nine (64·3%) out of the 14 MAP-positive cow-calf herds were infected. The percentage of positive environmental samples and the apparent within-herd prevalence (Spearman's P = 0·73, P < 0·001) as well as the herd-level test results (positive and negative) and the herd's status based on individual testing (Fisher's exact test, P = 0·014) showed a positive association. Considering limitations in low-prevalence herds, MAP-positive beef cow-calf herds are detectable by environmental samples in temperate climate zones.

Reduced vancomycin susceptibility (RVS) may lead to poor clinical outcomes in Staphylococcus aureus bacteraemia. We conducted a cohort study of 392 patients with S. aureus bacteraemia within a university health system. The association between RVS, as defined by both Etest [vancomycin minimum inhibitory concentration (MIC) >1·0 μg/ml] and broth microdilution (vancomycin MIC ⩾1·0 μg/ml), and patient and clinical variables were evaluated to create separate predictive models for RVS. In total, 134 (34·2%) and 73 (18·6%) patients had S. aureus isolates with RVS by Etest and broth microdilution, respectively. The final model for RVS by Etest included methicillin resistance [odds ratio (OR) 1·51, 95% confidence interval (CI) 0·97–2·34], non-white race (OR 0·67, 95% CI 0·42–1·07), healthcare-associated infection (OR 0·56, 95% CI 0·32–0·96), and receipt of any antimicrobial therapy ⩽30 days prior to the culture date (OR 3·06, 95% CI 1·72–5·44). The final model for RVS by broth microdilution included methicillin resistance (OR 2·45, 95% CI 1·42–4·24), admission through the emergency department (OR 0·54, 95% CI 0·32–0·92), presence of an intravascular device (OR 2·24, 95% CI 1·30–3·86), and malignancy (OR 0·51, 95% CI 0·26–1·00). The availability of an easy and rapid clinical prediction rule for early identification of RVS can be used to help guide the timely and individualized management of these serious infections.

Strains of Staphylococcus aureus were isolated at a single sampling from cows in a dairy herd. When typed by phage most showed a complex pattern of lysis with group III and IV phages. Cross-spotting of strains showed great lytic activity and ten phages were isolated. The parent strains were lysogenized with these phages and the effect on the phage typing pattern of 202 daughter strains from 25 parent cultures was studied. Phage action was often blocked completely, with up to four being blocked on the one strain. Those most frequently blocked were phage 101, 117, 307 and 42D.

Formic aldehyde, the simplest possible aldehyde, is a substance possessed of considerable biological and chemical interest. Its biological interest consists in the fact that it has long been regarded as forming the first product of plant assimilation, and has recently been actually demonstrated as such in plants. The ease with which this substance undergoes polymerisation resulting in the formation of sugars, under the influence of simple reagents, justifies the assumption that formic aldehyde is an essential link in the building-up of complex carbohydrates by plants. In addition to this it has recently been requisitioned as the only possible source of proteid anabolism. Its interest to the physiological chemist is that it combines energetically with proteids, and to a less extent with carbohydrates, effecting considerable alteration of their physical and physiological properties. This behaviour seems to be directly antagonistic to the biological rôle ascribed to the substance above. This apparent anomaly of the same substance being both a poison and an essential physiological constituent of living cells is discussed by Loew. It seems to depend upon the fact that what may be termed the biological formic aldehyde is present in small quantities (dilute solutions) and is quickly used up, owing to the ease with which it polymerises or forms innocuous compounds. This last property has an immediate bearing upon the subject of this inquiry in so far as it may serve to explain the results obtained by the administration of small quantities of formic aldehyde to man in his food. It is in this connection that formic aldehyde is of interest to us, and the importance of this subject is in our opinion sufficient to justify us in reviewing somewhat exhaustively the results of other observers with regard to the chemical and physiological properties of this substance.

1. Extracts containing non-infective soluble antigens have been prepared from the tissues of mice infected with a pantropic or any of three neurotropic strains of Rift Valley fever virus. The antigens were detectable by complement-fixation and gel-precipitin tests using antisera prepared in mice.

2. The extracts appeared to contain at least two antigens separable by electrophoresis and distinguishable by Ouchterlony tests. The faster migrating minor antigen occurs sparsely and was not further examined.

3. No distinction, physical or immunological, was observed between the major antigen derived from the four strains.

4. In gel diffusion-filtration experiments with granulated 7 % agarose, the major antigen appeared to be polydisperse containing particles with diffusion rates ranging from at least as low as that of Burnupena cincta haemocyanin to almost as high as that of haemoglobin.

5. Centrifugal analysis indicated the presence of particles having sedimentation constants of about 8, 29 and greater than 100 Svedberg units. These particles have a density of about 1·27 g./ml. If all the particles of the major antigen are spherical, with a density of 1·27 g./ml., the three size groups have diameters of about 7–8, 14 and < 26 mμ.

6. The diffusion coefficient of the smallest particle was estimated to be 6·06x 10−7 cm.2/sec. corresponding to a sphere 7 mμ in diameter, or 4·78 x 10−7 cm.2/ corresponding to a sphere 9 mμ in diameter depending on which of two values for the diffusion coefficient of mouse γ-globulin is used in the calculation.

7. In density gradient zone electrophoresis at pH 8·6, the principal antigen migrated at about the same rate as haemoglobin and appreciably slower than the virus. The authors are indebted to Prof. A. Kipps for his continued interest in this work, and to Dr T. H. Mead for valuable criticism of this paper. This investigation was supported in part by a Public Health Service research grant Al 04044–02 from the National Institute of Health, Bethesda, U.S.A.

In analysing some samples of air which had been sent for examination, the writer was struck by the presence of an altogether abnormal quantity of carbon dioxide associated with a very much diminished oxygen content. In view of this excess, the space from which these samples had been obtained was then thoroughly ventilated and after remaining closed for only four days the air was found to contain already 2·27 p.c. of carbon dioxide instead of the normal 0·03 p.c. No immediate explanation of the phenomenon was available and this paper contains a short account of the research made to discover the cause.

Although knowledge of principles determining variation is imperfect, some progress has been made and further help may be obtained from some of the newer conceptions about combining affinities regulating normal growth. There are reasons to believe that growth depends on a rhythmic cycle of synthesis, peculiar to living protein, whereby at each successive stage one particular “building stone” is selected for synthesis, with rejection of all others. There is also some evidence that the surface of a growing bacterium passes through periodic phases. Additional light on the activities of the bacterial surface is thrown by the new conception of enzymes which regards them not as fixed chemical entities but as chemico-physical “centres of activity.”

Some of the principles which are gradually coming to light in bacterial variation may ultimately be of assistance in the much more obscure problem of explaining the change from the normal mammalian cell to its malignant variant. I refer in particular to conceptions, which I have discussed in the preceding part of this article, about the mechanism of cellular growth and the nature of a cell's combining affinities.

Bacteriologists are not in a position to disregard the limitations recognised by the physiologists. Precise data which are not available from experiments are far from sufficient to explain the properties of living matter; they must be supplemented by vaguer conceptions about the functions of a cell, its internal organisation and its susceptibility to stimulative or inhibitory agencies—conceptions which cannot yet be translated into recognised chemical substances and physical properties. One must therefore start by recognising that bacterial virulence, being dependent on vital processes, cannot be fully explained in chemico-physical terms.

Sera of 197 apparently well persons were tested for residual haemagglutination-inhibiting antibodies against live Hong Kong/68, A/FM/47 and A/PR/34 strains. Sera of 62 well persons, regularly exposed to contacts with swine, were tested against an inactivated A/New Jersey/76 antigen.

Those born some time before and during a certain influenza era showed a significantly greater proportion of homologous residual titres against the subtype prevailing in that influenza era, than those born after the termination of the same era.

In each of the seven age groups tested both the percentage of positives and the geometric mean titres were usually highest against the Hong Kong strain (representing the most recent era); the next highest were those against the FM1 strain and the lowest were those against the PR8 strain (representing the most distant of these three influenza eras).

The serological involvement of donors exposed to regular contacts with swine was relatively stronger against the New Jersey antigen than the response of other serum donors shown against the other three, more recent, prototypes of influenza virus A. The oldest age groups showed significantly lower antibody response against the PR8, FM1 and Hong Kong strains (but not against the New Jersey antigen) than the next one or two of the younger age groups.

1. Though Shanghai is in close communication with ports in which plague is endemic, it has not suffered severely.

2. The number of human cases is small compared with the number of plague-infected rats found.

3. Both X. cheopis and C. fasciatus are found. Reasons are given for considering that X. cheopis is the chief agent in spreading plague, and that infection, being unlikely to reach Shanghai during the season when this flea flourishes, has difficulty in gaining a foothold.

4. The discrepancy between the number of cases of human and rat plague may possibly be explained by the habits of C. fasciatus.

Stored mixtures of the virus and corresponding antisera in foot-and-mouth disease have equal complement-fixing activity whether they are prepared from virus and serum of homologous or heterologous types. On ultracentrifugation the complement-fixing activity is removed from the mixture and the remaining antibody is more sharply type-specific in routine complement-fixation tests than the original serum.

The aim of this study was to evaluate potential sampling strategies for detection of infected flocks that could be applied during an outbreak of low pathogenicity notifiable avian influenza (LPNAI) initiated in duck holdings, following initial detection. A simulation model of avian influenza virus transmission and spread within and between holdings, respectively, was used to predict the impact on the size and duration of an outbreak of (i) changing the tracing window within which premises that might be the source of infection or that may have been infected by the index premises were sampled and (ii) changing the number of birds sampled in the flock being tested. It has shown that there is potential benefit in increasing the tracing window in terms of reducing the likelihood of a large outbreak. It has also shown that there is comparatively little benefit from increasing the number of birds sampled per flock.

Some studies have suggested that the Toll-like receptor 9 polymorphism (TLR9 rs352140) is closely related to the risk of bacterial meningitis (BM), but this is subject to controversy. This study set out to estimate whether the TLR9 rs352140 polymorphism confers an increased risk of BM. Relevant literature databases were searched including PubMed, Embase, the Cochrane Library and China National Knowledge Infrastructure (CNKI) up to August 2020. Seven case-control studies from four publications were enrolled in the present meta-analysis. Odds ratios (OR) and confidence intervals (95% CI) were calculated to estimate associations between BM risk and the target polymorphism. Significant associations identified were allele contrast (A vs. G: OR 0.66, 95% CI 0.59–0.75, P = 0.000), homozygote comparison (AA vs. AG/GG: OR 0.62, 95% CI 0.49–0.78, P = 0.000), heterozygote comparison (A vs. G: OR 0.74, 95% CI 0.61–0.91, P = 0.005), recessive genetic model (AA vs. AG/GG: OR 0.78, 95% CI 0.65–0.93, P = 0.006) and dominant genetic model (AA vs. AG/GG: OR 0.70, 95% CI 0.57–0.85, P = 0.000). The findings indicate that, in contrast to some studies, the TLR9 rs352140 polymorphism is associated with a decreased risk for BM.