Quantitative methods have been used in several investigations by Kabat and his colleagues (1945–50) in the study of serological relations of various preparations of blood-group substances. The investigations have taken twoforms: (1) the amounts of antibody nitrogen precipitated from a standard volume of an antiserum by varying amounts of the blood-group substances have been plotted against the amount of blood-group substance added; (2) the hexosamine has been measured in the precipitates formed with antiserum in the zone of antibody excess and the ratio of hexosamine precipitated to hexosamine in the blood-group substance added has been calculated; the amount of methyl-pentose precipitated has also been measured (Kabat, Baer &Knaub, 1949) and the ratio of methyl-pentose precipitated to methyl-pentose added hasbeen calculated.

IN 1913, Fraenkel and Much1 inoculated monkeys, guinea-pigs, rabbits and dogs intraperitoneally with large quantities of material obtained from two cases of Lymphadenoma, no accompanying tubercular disease being demonstrable. The material was broken down with antiformin, and as a result of the injections, the guinea-pigs died within three months. The authors state that besides finding extensive tubercular disease, there were hard, white nodules, the size of a cherry stone, on the serous coverings of the stomach and mesentery. Also, in addition to genuine tubercular disease of the lymphatic glands, they found giant cells, not of Langhans' type, as well as a stroma rich in fibriles, similar to what is found in Lymphadenoma. The nodules on the serous surfaces showed a picture corresponding to the terminal fibrous stage of a lymphadenomatous focus, with a scarcity of cellular elements.

A heterogeneous sample consisting of eighteen specimens of semen provided by eleven patients was examined. Smears were supravitally stained at 3, 8 and 27 hr. Counts of living and dead spermatozoa, classified into normal and fourteen types of abnormal forms, showed that whereas five abnormal forms were always dead, the remaining types showed varying proportions of dead and living cells. Their rate of mortality was somewhat greater than that of normal spermatozoa.

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.

We quantified the potential impact of different social distancing and self-isolation scenarios on the coronavirus disease 2019 (COVID-19) pandemic trajectory in Saudi Arabia and compared the modelling results to the confirmed epidemic trajectory. Using the susceptible, exposed, infected, quarantined and self-isolated, requiring hospitalisation, recovered/immune individuals, fatalities model, we assessed the impact of a non-pharmacological interventions’ subset. An unmitigated scenario (baseline), mitigation scenarios (25% reduction in social contact/twofold increase in self-isolation) and enhanced mitigation scenarios (50% reduction in social contact/twofold increase in self-isolation) were assessed and compared to the actual epidemic trajectory. For the unmitigated scenario, mitigation scenarios, enhanced mitigation scenarios and actual observed epidemic, the peak daily incidence rates (per 10 000 population) were 77.00, 16.00, 9.00 and 1.14 on days 71, 54, 35 and 136, respectively. The peak fatality rates were 35.00, 13.00, 5.00 and 0.016 on days 150, 125, 60 and 155, respectively. The R0 was 1.15, 1.14, 1.22 and 2.50, respectively. Aggressive implementation of social distancing and self-isolation contributed to the downward trend of the disease. We recommend using extensive models that comprehensively consider the natural history of COVID-19, social and behavioural patterns, age-specific data, actual network topology and population to elucidate the epidemic's magnitude and trajectory.

We present the comparative characterisation of 195 non-aureus staphylococci (NAS) isolates obtained from sheep (n = 125) and humans (n = 70) in Sardinia, Italy, identified at the species level by gap gene polymerase chain reaction (PCR) followed by restriction fragment length polymorphism analysis with AluI. Isolates were tested phenotypically with a disc diffusion method and genotypically by PCR, for resistance to 11 antimicrobial agents including cationic antiseptic agents. Among the ovine isolates, Staphylococcus epidermidis (n = 57), S. chromogenes (n = 29), S. haemolyticus (n = 17), S. simulans (n = 8) and S. caprae (n = 6) were the most prevalent species, while among human isolates, S. haemolyticus (n = 28) and S. epidermidis (n = 26) were predominant, followed by S. lugdunensis and S. hominis (n = 4). Of the 125 ovine isolates, 79 (63.2%) did not carry any of the resistance genes tested, while the remainder carried resistance genes for at least one antibiotic. The highest resistance rates among ovine isolates were recorded against tetracycline (20.8%), and penicillin (15.2%); none was resistant to methicillin and two exhibited multidrug resistance (MDR); one of which was positive for the antiseptic resistance smr gene. By contrast, most human isolates (59/70, 84.3%) were resistant to ⩾1 antimicrobials, and 41 (58.6%) were MDR. All 52 (74.3%) penicillin-resistant isolates possessed the blaZ gene, and 33 of 70 (47.1%) harboured the mec gene; of these, seven were characterised by the Staphylococcal Chromosomal Cassette (SCCmec) type IV, 6 the type V, 5 of type III and one representative each of type I and type II. The majority (57.1%) was erythromycin-resistant and 17 isolates carried only the efflux msrA gene, 11 the methylase ermC gene and an equal number harboured both of the latter genes. Moreover, 23 (32.8%) were tetracycline-resistant and all but one possessed only the efflux tetK gene. qacA/B and smr genes were detected in 27 (38.6%) and 18 (25.7%) human NAS, respectively. These results underline a marked difference in species distribution and antimicrobial resistance between ovine and human-derived NAS.

A serious outbreak of staphylococcal infections in the maternity units in Blackburn was investigated. There were considerably more than one hundred cases of breast abscesses altogether, well over half of which occurred in primiparae. Staphylococcus aureus, phage type 80, was the predominating organism throughout the outbreak and at the peak period during the early part of the outbreak this type was responsible for nearly 80% of the infections.

After the introduction of a number of procedures for the general reduction of cross-infection the incidence of breast abscess fell markedly and a controlled trial of an antibacterial cream, containing neomycin and hibitane, which was applied to the nasal mucosa of all infants and mothers in the test group of patients, was undertaken. The conditions obtaining in the test and control groups were identical in every way except that the control patients did not receive the neomycin-hibitane cream. There were about 1250 mothers and infants each in the test and control groups; the incidence of breast abscesses in the test group was 0·8% and in the control group it was 2·7%. The method adopted for the detection and treatment of carriers among the nursing staff broke down on two occasions; this fact and the emergence of an unforeseen source resulted in a larger number of infections than should have occurred. Had it not been for these incidents there is little doubt that the trial would have shown more conclusively the effectiveness of the neomycinhibitane cream, by the method laid down, in reducing cross-infection.

Investigation of the bacterial flora on the nasal mucosa of over 1000 infants in the control group yielded results of considerable interest. Of 300 cases where there was early colonization by Staph. albus, this organism established its dominating position in 70% of the cases and it was not subsequently displaced by Staph. aureus. The significance of this observation and the evidence favouring nasal dissemination of Staph.aureus as the most important cause of hospital cross-infection are discussed.

Presence of thermolabile agglutination-inhibiting substances in strains of the genus Shigella has been demonstrated by numerous authors. Archer (1942) used as antigen for agglutination tests with S. alkalescens cultures which had been killed at 100° C., since a thermolabile factor which prevents agglutination by the usual technique had been found present in the organism. The same method was employed by Mendes Silva (1943) in agglutination tests with S. ambigua. Braun & Unat (1943) found in S. paradysenteriae (Flexner) a labile antigen designated ‘O1’ which inhibits O-agglutination of the living bacteria. Schuetze (1944) reported that the insensitivity of S. dysenteriae (Shiga) to agglutination is abolished by heating at 100° C. for 30 min. Weil, Black & Farsetta (1944) reported that boiling for 1 hr. renders inagglutinable strains of S. paradysenteriae (Flexner) fully agglutinable. Recently, Weil et al. (1946) reported that one of the Sachs types contains an inhibiting substance, a heat labile antigen and a heat stable antigen. He observed inhibition of agglutination of living bacteria in many Flexner types, S. alkalescens and S. ambigua. Olitzki, Shelubsky & Koch (1946) reported that there is present in S. dysenteriae (Shiga) a labile substance ‘I’ which inhibits the agglutination of thd living bacteria. They were able to demonstrate a labile antigen in toxic saline extracts but not in the intact bacteria. The present paper reports a method for isolation of this antigen in the form of a relatively concentrated preparation.

Fluorescein dispersed as powder into the air of occupied rooms was extracted in measurable quantities from dust after as many as twenty previous sweepings.

The value of fluorescein in showing the rate of removal of dust from occupied environments is discussed in relation to the transfer of infection.

Since 2003, Connecticut laboratories have reported Gram-positive rod (GPR) isolates detected within 32 h of inoculation from blood or cerebrospinal fluid. The objectives were to rapidly identify inhalational anthrax and unusual Clostridium spp. infections, and to establish round-the-clock laboratory reporting of potential indicators of bioterrorism. From 2003 to 2006, Connecticut's GPR surveillance system identified 1134 isolates, including 657 Bacillus spp. (none B. anthracis) and 241 Clostridium spp. Reporting completeness and timeliness improved to 93% and 92%, respectively. Baseline rates of Bacillus spp., Clostridium spp. and other GPR findings have been established and are stable. Thus far, no cases of anthrax and no unusual clusters of Clostridium spp. have been detected by the GPR surveillance system. This system would probably have confirmed the inhalational anthrax case in Pennsylvania in 2006 3 days sooner than traditional reporting. Using audits and ongoing evaluation, the system has evolved into a highly functional 24/7 laboratory telephone reporting system with almost complete reporting.

The organisms described as Bacillus wakefield and considered to be members of the Flexner group are not dysentery bacilli. They are paracolon bacilli containing α-antigen.

In the preceding reports on infant mortality in counties during 1908 (Cd. 5263), in 241 urban areas in 1907–10 (Cd. 6909), and in Lancashire (Cd. 7511), the chief environmental circumstances favouring excessive infant mortality have been enumerated and to some extent discussed.

Asymptomatic carriage of Staphylococcus aureus is an important risk factor for developing infection, as well as a key contributor to transmission. Despite the fact that childcare workers are at known risk for infections, little research has focused on bacterial carriage in this occupational group. We conducted a cross-sectional study comparing the prevalence of S. aureus in 110 childcare employees with the prevalence in 111 unexposed participants. Questionnaire data was collected for employees, unexposed adults, and children. Multivariate analysis allowed for adjustment for confounders. Data on work-related exposures are presented as well. The prevalence of S. aureus in employees, unexposed adults, children, and on surfaces was 35·2%, 33·6%, 19·8%, and 9·8%, respectively. Washing children's hands upon their arrival at childcare facilities may decrease the risk of S. aureus carriage in employees (odds ratio 0·17, 95% confidence interval 0·095–0·32, P < 0·0001).

The returns relating to naval personnel who were reported to the Admiralty to have acquired non-surgical jaundice between 1944 and 1947 were examined.

Where the dates of onset of illness and of inoculation were available, the numbers who developed the illness within 11–40 days of inoculation were greater than the numbers to be expected if there was no association between the dates of onset of illness and the dates of inoculation. During 1945 the observed numbers were also greater than the expected numbers when 41–70 days intervened between inoculation and the illness.

The interpretation and practical implications of the findings are discussed.

This paper is published by kind permission of the Medical Director General of the Navy, Surgeon Vice-Admiral Sir Alexander Ingleby-Mackenzie.

I am indebted to Dr F. O. MacCallum for his continued interest and for invaluable suggestions; to Dr J. O. Irwin for scrutinizing the script; to Miss H. M. Ferres who applied the statistical tests to the figures in Table 1; to Surgeon Commander M. A. Rugg-Gunn, Royal Navy, for the information about the ratings' pay books, and to Senior Commissioned Wardmaster J. L. T. Burns, Royal Navy, and Sick Berth Petty Officer (L) D. E. Lee, Royal Navy, who tabulated the numerical data.

Control of houseflies by modern insecticides is becoming unreliable owing to emergence of resistant strains, so that some older measures deserve reconsideration. Exclusion of mosquitoes by gauze has been studied experimentally but not, apparently, of houseflies.

Some simple tests show that a suitable gauze to exclude houseflies (and larger insects) would be 10 mesh 32 s.w.g. with an aperture 2·17 mm. square. This compares with a gauze recommended for excluding mosquitoes, 18 mesh and 32 s.w.g. with an aperture 1·16 mm. square.

The advantages of the wider gauze for flies are admission of more light and air and lower cost. Some simple experiments on the relative air resistance of mosquito ind fly gauze were made by a method involving retardation of a pendulum by a gauze circle. The results suggest that the obstruction to ventilation is roughly proportional to the percentage obstruction (as with light) which was 20 % for the fly gauze and 36 % with the mosquito gauze.

In laboratory experiments the acute eye irritation produced by exposure to tap water was not significantly increased when chlorine compounds were added to the water at concentrations of 1 mg./l. The greatest irritation was produced by 2 mg. Cl2/1. as NH2C1. The addition of NaCl at concentrations above about 0·5% abolished the irritant effect of tap water, and prevented irritation even when 1 mg. Cl2/1. was present.

In a field experiment involving two swimming baths, one with fresh and the other with saline water (0·5 % NaCl), eye irritation in the saline bath was significantly lower than in the freshwater bath only when the swimming time did not exceed 30 min.

In the course of experiments on the cultivation of anaerobic bacilli, it was found advisable to be able to calculate with some certainty on the production of spores by the strains of anaerobes worked with. Observations were accordingly made of the conditions of cultivation by which sporulation appeared to be influenced. It was evident that in the case of B. sporogenes and other well-known types observed, the proportion of spores produced within a given period varied markedly in response to variations in the same factors that mainly influenced the rate of growth in cultures, viz. concentration of food material, incubation temperature, and reaction of medium. With the exception of cultures in media containing added carbohydrate, it was evidently also the rule that sporulation was most active in cultures commencing under conditions most favourable to rapidity of vegetation.