Modified brilliant green agar (BGA), Muller-Kauffmann tetrathionate, Rappaport's and selenite F broths were compared for their efficiency in isolating salmonellas from pigs and their excreta. It was concluded that BGA and Rappaport's broth were the media of choice. Where searches were made for Salmonella choleraesuis alone, the use of a trehalose McConkey agar provided a rapid method of differentiating S. cholerae-suis, which does not ferment trehalose, from the majority of other salmonellas, which do ferment trehalose.

Casualties were collected from two farms where infection with S. cholerae-suis was endemic. The isolation rates of S. cholerae-suis from different carcase sites were compared in order to determine the relative importance of the salivary, upper respiratory and faecal routes of excretion. S. cholerae-suis was isolated from numerous carcase sites in carriers including the salivary glands, tonsils, trachea and lungs. However, isolations from the nasal passages, mouth, pharynx and gastro-intestinal tract of carriers were either infrequent or absent. When, in a further study, S. cholerae-suis was isolated from only 3/414 faeces, 1/170 nasal swabs and not at all from 170 oral swabs taken from live pigs, it was concluded that there must be more significant modes of transmission than from the salivary glands, upper respiratory or gastro-intestinal tracts. Cannibalism was considered to be a possibility.

In contrast to S. cholerae-suis, other salmonellas were frequently isolated from randomly collected faeces and from the gastro-intestinal tract as well as other sites in casualties.

In a study on the serotypes of Escherichia coli which are present in the faeces of students travelling from many parts of the world to Dublin, a great variety of types was found. It was not possible to relate certain types to the various parts of the world where the students came from. There was no decrease in variety of serotypes after the students had been in Dublin for a few months and no distinctive ‘Dublin’ types were acquired. Serological variation of the E. coli was suggested as partially explaining some of the variety of the serotypes found. Although eight students developed diarrhoea without an aetiological agent being isolated after arrival in Dublin, no distinct pattern of E. coli could be related to this.

It was shown in this work that the electrophoretic mobility of the MEF1 strain of poliovirus was increased approximately 25% after interrupted inactivation with formaldehyde. This is in accordance with past observations on the behaviour of formaldehyde-treated proteins. The residual live virus had the same mobility as the ‘killed’ virus, thus indicating that the surfaces of all the virus particles have been affected to the same degree by the inactivating agent.

Gel precipitin tests performed on the different samples obtained by zone electro-phoresis showed, in addition to the main antigen, the presence of a small amount of a second component of slightly higher mobility, and, as it occurs in the main fraction and the sample thereafter it probably has a slightly higher mobility than the main component.

The antigenic properties of the different fractions as shown by the production of antibodies in guinea-pigs correspond with the presence of precipitating antigen in the samples in the region of highest antigen concentration. The faint antigenicities of the fractions obtained from the regions higher up in the zone electrophoresis column are due to small amounts of virus antigen similar to that found in the column on electrophoresis of untreated MEF1 virus, bearing in mind that the inactivated virus was concentrated approximately 2000 times for zone electrophoresis.

General interest was first aroused regarding the respective powers of the human and bovine types of the tubercle bacillus to infect the human subject by the address of Koch at the Tuberculosis Congress in 1901. In this he stated that the two types produced different diseases, and that the amount of human tuberculosis due to infection by the bovine type of the tubercle bacillus was negligible.

1. A consecutive series of 400 cases of diphtheria from the Romford (Essex) area have been bacteriologically typed and correlated with the clinical findings.

2. Gravis infection was found to be the most prevalent type.

3. The intermedius type was the most lethal and severe.

4. Mitis infection formed the smallest proportion of cases, usually of a mild character.

5. Laryngeal cases were few, and all three bacteriological types were represented.

6. A large proportion of children of 7 years and over were attacked.

1. Powerful anti-sera may be produced by the intravenous injection of smaller quantities of serum than have hitherto generally been used (p. 260).

2. Nuttall's quantitative method affords a simple and fairly accurate means of determining the quantity of precipitum formed. By its means quantitative differences can be appreciated which are scarcely, or not at all, apparent in the tubes on inspection (p. 263).

3. Normal saline solution is the best diluent for normal sera, and 1—21 has been found to be a convenient dilution. Increase of salt has very little effect on the production of precipitum (p. 266).

4. The quantity of precipitum formed is not influenced by the temperature at which the experiment is conducted (i.e. between the temperature of the ice-chest and 37° C.) (p. 268).

5. In the case of dried bloods time per se does not destroy their capacity for reacting with their homologous anti-sera. Fluid sera appear to deteriorate slightly by keeping (pp. 269—274).

6. Putrefaction of the serum, or anti-serum, does not affect the production of a specific precipitum (p. 274).

7. Although the intimate mixture of lime and blood completely destroys the latter, the former is not present in sufficient quantity in ordinary earths to affect blood mixed with earth. The presence of small quantities of lime, however, gives rise to a clouding in solution, which can be got rid of by the passage of CO2, and subsequent filtration (pp. 276—281).

8. The presence of even small quantities of acids, or alkalis, rapidly reduces the quantity of precipitum formed (pp. 281—284).

9. In diseased conditions a marked alteration may occur in the quantity of precipitum (pp. 265 and 285).

10. The volatile antiseptics produce little effect on sera, even after long contact, but formalin, corrosive sublimate, lysol, lysoform, the sulphates of copper and iron, and nitrate of silver, especially in strong solutions, exert a very deleterious action (pp. 287 and 358).

11. Blood dried on fabrics, and materials in common use (with the exception of certain leathers) may with adequate precautions be readily diagnosed (p. 290).

12. After an undiluted anti-serum has been raised to a temperature beyond 60° C. the capacity for producing precipitum is diminished, and it is destroyed completely after exposure to 68° C. These effects seem to be produced at lower temperatures in normal undiluted sera (pp. 354–55).

13. The precipitum-producing power of normal sera is reduced by filtration through a Chamberland filter, but not by passage through a Berkefeld filter (as far as the experiment was conducted) (p. 357).

A prospective study of norovirus outbreaks in Ireland was carried out over a 1-year period from 1 October 2004 to 30 September 2005. Epidemiological and molecular data on norovirus outbreaks in the Republic of Ireland (ROI) and Northern Ireland (NI) were collected and combined in real time in a common database. Most reported outbreaks occurred in hospitals and residential institutions and person-to-person spread was the predominant mode of transmission. The predominant circulating norovirus strain was the GII.4-2004 strain with a small number of outbreaks due to GII.2. This study represents the first time that enhanced epidemiological and virological data on norovirus outbreaks in Ireland have been described. The link established between the epidemiological and virological institutions during the course of this study has been continued and the data is being used as a source of data for the Foodborne Viruses in Europe Network (DIVINE-NET).

This study utilizes parallel, longitudinal entomological and parasitological data collected during a 5-year vector control programme in Pondicherry, South India, to quantify Wuchereria bancrofti transmission from the vector to the human population. A simple mathematical model, derived from the standard catalytic model, is used to examine the hypothesis that current infection prevalence in young children is a dynamical function of their cumulative past exposure to infective bites. Maximum likelihood fits of the model to the observed data indicate a constant child infection rate with age, above a threshold representing the pre-patent period, or equivalently, the cumulative biting intensity required to produce patent infections. Extrapolation of the model allows the crude estimation of the equilibrium microfilaria age-prevalence curve due to control. The results suggest that vector control alone may have little impact on the overall age-prevalence of infection even when sustained for long periods. These observations are discussed in terms of the likely impact of density dependent mechanisms, such as acquired immunity, on model predictions.

In the following paper an attempt will be made to give a description of certain characteristic features which we have observed on postmortem examination of a large number of plague rats in the course of the daily routine rat investigation in Bombay. An account of the diagnosis of rat plague may appear at first sight to cover well-known ground and to be consequently unnecessary. Having regard however to its importance the subject seems to have received remarkably little attention, judging from the scattered references to it in the literature.

Attack by the cercariae of Schistosoma haematobium, S. mansoni and S. japonicum causes in man debilitating diseases which in certain countries are widespread. Infection is mainly through the skin, though it can occur through drinking water containing the parasites. It has been shown by Sproule (1939) that freshly liberated vigorous cercariae of S. haematobium and S. mansoni are killed in 30 min. by superchlorination to the extent of one dose beyond that indicated in the Horrocks test. This of course does not deal with skin infection, and though bathing in fresh water may be avoided and water drawn off may possibly be stored till all cercariae are dead, yet it is obviously impossible entirely to avoid contact with natural waters. In U.S.A. and Canada dermatitis is caused at many otherwise desirable lacustrine bathing beaches by cercariae liberated from Stagnicola emarginata and other snails which live in shallow water on sandy bottoms (Cort, 1928; Brackett, 1941). The final hosts are apparently water birds and in man these cercariae tunnel in the epithelial layer of the skin and soon disintegrate. No dangerous disease is caused, but there is much discomfort, especially among children who naturally keep to the shallow water. Penetration takes place largely as the water film dries and oiling the skin is no preventive. McMullen (1941) has given an account of attempts to eliminate the parasites by poisoning the snail hosts with copper sulphate or a sulphate carbonate mixture. A temporary success can be achieved at considerable cost.

We report a family cluster of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection involving five patients in a family cluster in Dazhou, China, including the epidemiological, clinical, laboratory and radiological findings. Three-generation transmission was observed. Through epidemiological investigation, we observed asymptomatic transmission to a cohabiting family member, as well as person-to-person transmission of SARS-CoV-2 outside Wuhan city. The asymptomatic transmission demonstrated here provides evidence that there could be a greater risk of Coronavirus Disease 2019 (COVID-19) spread. This cluster also demonstrated that COVID-19 is transmissible during the incubation period of an asymptomatic person. Early isolation and treatment, stressing prevention of cluster outbreaks, could help prevent further spread of the epidemic.

In a recent Report (1) upon the new parasitic bodies associated with tropical splenomegaly, Lieut. S. R. Christophers, I.M.S., published a method of producing chromatin staining in sections. This method, however, labours under the disadvantage that, after staining, the section must be dried in the air before it is cleared and mounted, since the chromatin reaction is lost if dehydration by absolute alcohol is attempted. The consequent shrinkage of the tissue, even in very thin sections, renders the method of little service for delicate work.

The aetiology of acute respiratory infections between September 1962 and August 1963 was studied in two general practices in Cambridge. These practices were reasonably representative of the permanent community of Cambridge.

There were 592 spells of acute respiratory infection in the combined practices, representing an incidence of 11·4 spells per 100 persons. Children aged 0–4 had the highest rates (51·6 spells per 100 persons).

It was possible to establish a diagnosis in 62·5% of cases investigated. Influenza and parainfluenza infections featured prominently, being responsible between them for 46·6% of all respiratory infections investigated. From September 1962 to January 1963, parainfluenza viruses were prevalent, causing acute laryngo-tracheo-bronchitis in children (croup), and an influenza-like illness in adults. From February to April 1963, influenza A (Asian) was epidemic, a clinical diagnosis of influenza being frequently confirmed by laboratory studies at this time. There were nine cases of Eaton agent infection, seven of which had PAP, the other two being family contacts who later developed influenza-like illnesses.

Adenovirus (four cases), and RS virus (three cases) were not prevalent to any large extent in Cambridge during the survey.

The ability of the pyrogenic silica Aerosil 380R to exclude non-specific serum inhibitors (NSI) of rubella virus haemagglutination was evaluated. The developed procedure was compared with the kaolin, heparin/MnCl2 and dextran sulphate/CaCl2 methods.

Aerosil and kaolin were found superior for the elimination of non-specific inhibitors and high density lipoproteins (HDL). The other methods left NSI and HDL in a majority of the sera, occasionally in high titres. Aerosil seemed to be somewhat more efficient than kaolin in NSI and HDL exclusion. The Aerosil method offers the opportunity to detect sera with rubella antibody titres < 10. Among eight such sera, six were shown to contain rubella antibodies, while two were false positives.

Comparative measurements are recorded of the osmotic pressures of human and rabbit sera, both fresh and re-dissolved after drying from the frozen state (F.D. sera).

The process of drying did not alter the osmotic properties of the serum proteins.

The view that drying from the frozen state does not cause denaturation of the serum proteins is supported also by the facts that the refractive indices and the membrane potentials remained unchanged.

The neutralizing activities of fowl, rabbit and mouse antisera prepared against TRIC agents were enhanced, in some cases over a 100-fold, by the addition of antiserum against the appropriate IgG. Significant non-specific inactivation of the organisms was observed in the absence of antiserum against TRIC agents, in reaction mixtures containing normal serum and antiserum against IgG. Since the extent of this inactivation showed a prozone, control tests with dilutions of normal serum equivalent to the full range of dilutions of the antiserum tested are necessary to show that enhancement of neutralization is specific.

Observations are reported on the mechanism of transmission of a neurotropic strain of Newcastle disease virus from infected to normal baby chicks. Infection appeared to be mediated mainly by large or very labile air-borne particles. Other factors examined were the time of maximum infectivity of chicks, the effects of duration of contact, of the social habits of the chicks and of the type of cage used to house them.

Results obtained by contact experiments were supported by tests in which settling virus particles were collected in Petri dishes placed at various distances from infected chicks.

Invasive fungal diseases have emerged as important causes of morbidity and mortality in haematological patients. In this study air samples were collected in two haematopoietic stem cell transplantation (HSCT) units, in which distinct air-control systems were in place. In hospital 1 no high-efficiency particulate air (HEPA) filter was available whereas in hospital 2 HSCT rooms were equipped with HEPA filters, with positive air pressure in relation to the corridor. A total of 117 samples from rooms, toilets and corridors were obtained during December 2009 to January 2011, using a six-stage Andersen sampler. In both hospitals, the concentration of potentially pathogenic fungi in the air was reduced in patients' rooms compared to corridors (P < 0·0001). Despite the presence of a HEPA filter in hospital 2, rooms in both hospitals showed similar concentrations of potentially pathogenic fungi (P = 0·714). These findings may be explained by the implementation of additional protective measures in hospital 1, emphasizing the importance of such measures in protected environments.

1. The production of soluble antigen in the chorioallantoic membranes at 6 hr. can be used to measure the infectivity of influenza virus preparations.

2. Intracellular virus is much more infective when tested by soluble antigen production at 6 hr. than when tested by conventional methods.

3. It is suggested that intracellular virus differs from extracellular because more virus particles per cell are required to initiate infection.

The author is greatly indebted to Dr L. Hoyle for his advice and encouragement throughout this work. Mr G. Field gave valuable help with the mathematics.

The purpose of this study was to apply a novel statistical method for variable selection and a model-based approach for filling data gaps in mortality rates associated with foodborne diseases using the WHO Vital Registration mortality dataset. Correlation analysis and elastic net regularization methods were applied to drop redundant variables and to select the most meaningful subset of predictors. Whenever predictor data were missing, multiple imputation was used to fill in plausible values. Cluster analysis was applied to identify similar groups of countries based on the values of the predictors. Finally, a Bayesian hierarchical regression model was fit to the final dataset for predicting mortality rates. From 113 potential predictors, 32 were retained after correlation analysis. Out of these 32 predictors, eight with non-zero coefficients were selected using the elastic net regularization method. Based on the values of these variables, four clusters of countries were identified. The uncertainty of predictions was large for countries within clusters lacking mortality rates, and it was low for a cluster that had mortality rate information. Our results demonstrated that, using Bayesian hierarchical regression models, a data-driven clustering of countries and a meaningful subset of predictors can be used to fill data gaps in foodborne disease mortality.