Experiments were carried out in a test chamber of 16,500 cu.ft. capacity with air conditioned at 68° F. and 54% relative humidity. Ventilation was controlled at 3·0 changes/hr., air being recirculated with 0·5 air change/hr. of fresh air admitted. By spraying into the air ducting a concentrated suspension of Chr. prodigiosum a bacterial cloud was introduced into the chamber of over 5 × 106 organisms/cu.ft. of air as l μ particles. Viable organisms were still present in the atmosphere after 6 hr.

When a heat-generated vapour of hexylresorcinol was introduced in a concentration of between 6 and 7 μg/cu.ft. of air the bacterial count dropped from nearly one million organisms per cu.ft. to fewer than ten in 35 min.

When the bacterial suspension was sprayed into the chamber with hexylresorcinol vapour present, the peak concentration reached was about one-quarter and on stopping the spray, the bacterial count fell from one million per cu.ft. to fewer than ten in less than 25 min.

Hexylresorcinol is also effective when the bacterial aerosol is in particles of 6–7 μ in size (approx. 100 bacteria per particle).

Hexylresorcinol has no effect against a bacterial aerosol of B. subtilis spores in 1 μ particles.

No attempt has been made to analyse the mode of action of hexylresorcinol in diminishing the bacterial content of the air. The evidence collected clearly indicates the necessity for further study of this problem.

Skin reactions have been produced in normal subjects by the injection of highly purified influenza A and B viruses. The reactions reached a maximum at 24–48 hr. and the histological pattern was compatible with a delayed hypersensitivity reaction. There was no close relation between skin test results and circulating antibodies. Twenty-seven subjects were challenged intranasally with attenuated influenza A (H3N2): 5 of 14 skin-test-negative subjects were infected, but none of 13 skin-test-positive subjects.

The incidence of haemagglutination inhibition (HI) antibody (titre ≥ 12) to influenza A/Singapore/1/57(H2N2) in sera collected from a Finnish population in the summer of 1981 was 58%. Subjects born after 1968 were essentially seronegative, and a comparable low HI antibody status was also recorded among the elderly, lowest being in people born during the period 1901–10. A small increase in antibody titre to the H2N2 virus was observed in the different age groups after infections with the H3N2, but not the H1N1, subtype influenza A viruses. The heterotypic response, which could be due to HI or NA antibodies, was restricted almost exclusively to subjects already exhibiting this antibody in acute phase sera. Moreover, the anamnestic boosting was not as strong as that described in earlier studies from samples collected at the beginning of the present era of H3N2 viruses.At population level, the HI antibody status to H2N2 was about the same at the beginning and end of the follow-up period which covered eight epidemic seasons. The results are discussed with respect to the doctrine of ‘original antigenic sin’ and to the threat of re-emergence of the H2N2 viruses.

Pathogen spillover from wildlife to humans or domestic animals requires a series of conditions to align with space and time. Comparing these conditions between times and locations where spillover does and does not occur presents opportunities to understand the factors that shape spillover risk. Bovine rabies transmitted by vampire bats was first confirmed in 1911 and has since been detected across the distribution of vampire bats. However, Uruguay is an exception. Uruguay was free of bovine rabies until 2007, despite high-cattle densities, the presence of vampire bats and a strong surveillance system. To explore why Uruguay was free of bovine rabies until recently, we review the historic literature and reconstruct the conditions that would allow rabies invasion into Uruguay. We used available historical records on the abundance of livestock and wildlife, the vampire bat distribution and occurrence of rabies outbreaks, as well as environmental modifications, to propose four alternative hypotheses to explain rabies virus emergence and spillover: bat movement, viral invasion, surveillance failure and environmental changes. While future statistical modelling efforts will be required to disentangle these hypotheses, we here show how a detailed historical analysis can be used to generate testable predictions for the conditions leading to pathogen spillover.

Pulsed-field gel electrophoresis genotypes of Campylobacter isolates from 603 human patients were compared with 485 isolates from retail offal (primarily chicken and lamb) to identify temporal clusters and possible sources of campylobacteriosis. Detailed epidemiological information was collected from 364 of the patients, and when combined with genotyping data allowed a putative transmission pathway of campylobacteriosis to be assigned for 88% of patients. The sources of infection were 47% food, 28% direct animal contact, 7% overseas travel, 4% person-to-person transmission and 3% water-related. A significant summer increase in campylobacteriosis cases was primarily attributed to an increase in food-related cases. Genotyping of isolates was essential for identifying the likely cause of infection for individuals. However, a more rapid and cheaper typing tool for Campylobacter is needed, which if applied to human and animal isolates on a routine basis could advance greatly our understanding of the ongoing problem of Campylobacter infection in New Zealand.

1. In the absence of the epidemic prevalence of the dysenteries over a period of 30 months it is found that cases of the various forms of dysentery as occurring in Aberdeen have been in the proportion of 1 amoebic, to 3 Flexner, to 6 Sonne dysenteries, and it is concluded that B. dysenteriae Sonne is the most frequent cause of dysenteric outbreaks in Aberdeen in non-epidemic times.

2. A description of the clinical and bacteriological features of Sonne dysentery is submitted.

3. Preliminary experiments, undertaken with a view to ascertaining whether B. dysenteriae Sonne produces a true exo-toxin, are described.

A report on Toxoplasma gondii by the UK Advisory Committee on the Microbiological Safety of Food recommended that more accurate figures on the burden of disease in the UK are needed. We present the first 5 years of data from an enhanced surveillance scheme for toxoplasmosis in England and Wales. Between 2008 and 2012, 1824 cases were reported, with an average of 365 each year. There were 1109 immunocompetent cases, the majority presenting with lymphadenopathy, and 364 immunosuppressed cases, with central nervous system and systemic symptoms most frequently reported. There were also 190 pregnant and 33 congenital cases. Of the pregnant cases, 148 were asymptomatic (probably detected during screening), while 28 suffered a fetal loss or stillbirth. The enhanced surveillance system has led to an improvement in the detection of toxoplasmosis in England and Wales. However, numbers are still likely to be an underestimate, biasing towards the more severe infections.

Haemorrhagic fever with renal syndrome (HFRS) is transmitted to humans mainly by rodents and this transmission could be easily influenced by meteorological factors. Given the long-term changes in climate associated with global climate change, it is important to better identify the effects of meteorological factors of HFRS in epidemic areas. Shandong province is one of the most seriously suffered provinces of HFRS in China. Daily HFRS data and meteorological data from 2007 to 2012 in Shandong province were applied. Quasi-Poisson regression with the distributed lag non-linear model was used to estimate the influences of mean temperature and Diurnal temperature range (DTR) on HFRS by sex, adjusting for the effects of relative humidity, precipitation, day-of-the-week, long-term trends and seasonality. A total of 6707 HFRS cases were reported in our study. The two peaks of HFRS were from March to June and from October to December, particularly, the latter peak in 2012. The estimated effects of mean temperature and DTR on HFRS were non-linear. The immediate and strong effect of low temperature and high DTR on HFRS was found. The lowest temperature −8.86°C at lag 0 days indicated the largest related relative risk (RRs) with the reference (14.85 °C), respectively, 1.46 (95% CI 1.11–1.90) for total cases, 1.33 (95% CI 1.00–1.78) for the males and 1.76 (95% CI 1.12–2.79) for the females. Highest DTR was associated with a higher risk on HFRS, the largest RRs (95% CI) were obtained when DTR = 15.97 °C with a reference at 8.62 °C, with 1.26 (0.96–1.64) for total cases and 1.52 (0.97–2.38) for the female at lag 0 days, 1.22 (1.05–1.41) for the male at lag 5 days. Non-linear lag effects of mean temperature and DTR on HFRS were identified and there were slight differences for different sexes.

We present a basic mathematical model of Staphylococcus aureus transmission in the USA based on natural history of infection and nationally representative data. We employed a Susceptible-Colonized-Infected-Recovered-Susceptible compartmental modelling framework with two different phenotypes of S. aureus: methicillin-susceptible (MSSA) and methicillin-resistant (MRSA). The model is dynamic and accounts for the US population growth. For model calibration/validation, we used published 1999–2005 S. aureus infection data in conjunction with the 2001–2004 National Health and Nutrition Examination Survey colonization data. Baseline model projections illustrated how MRSA might continue to expand and gradually replace MSSA over time, in the absence of intervention, if there is strong competition for colonization. The model-based estimate of the basic reproduction number (R0) highlights the need for infection control. We illustrate the potential population-level impact of intervention with a hypothetical S. aureus vaccination component.

Hepatitis B carriers who acquired the infection perinatally die from hepatocellular carcinoma (HCC) and cirrhosis at high rates. Published cohort studies are largely limited to males and are too small to estimate the age-specific risk of death. We therefore used routinely collected Hong Kong data to estimate the risks. Deaths were partitioned between carriers and non-carriers, then current life table calculations determined life expectancy and probability of dying from HCC or cirrhosis. HCC is the dominant cause of death for male carriers in middle adulthood with a lifetime risk of 27% for HCC compared to 4% for females. Predicted life expectancy is 72 years for male carriers, compared to 79 years for non-carriers. Female carriers have a life expectancy of 81 years and non-carriers 83 years. This model probably applies to all southern Chinese populations and emigrants with similar life history, and other populations that acquired infection early in life.

1. A minority only of scarlatina streptococci are agglutinated by antisera for individual strains and no group agglutination has been observed.

2. Absorption tests reveal the existence of common or generalised agglutinogenic constituents but these are not restricted to scarlatina strains and can be recognised among the majority of the haemolytic streptococci isolated from various sources.

3. Though certain serological groups among scarlatina streptococci may be recognised as corresponding generally to “types” described by Smith and Griffith, there is such considerable antigenic overlap among the different groups that the differentiation and relationship of strains cannot be expressed satisfactorily by formulating definite serological types.

4. A system of serological analysis of scarlatina and other haemolytic streptococci is suggested (see Table IV).

5. While strains presenting particular serological characters may be associated more frequently with scarlatina, haemolytic streptococci with common serological characters occur both in scarlatina and other conditions. No essential serological distinction can be drawn between scarlatinal and other haemolytic streptococci and a “Streptococcus scarlatinae” group cannot be defined by serological methods.

6. Among the haemolytic streptococci derived from conditions other than scarlatina no relationship exists between serological characteristics and toxigenic properties (as evidenced by cutaneous reactions to culture nitrates).

We have to thank Drs J. Smith and F. Griffith for cultures of the type strains referred to in the text.

The diagnosis of abortion in cattle caused by Salmonella dublin depends upon the isolation of the organism from either the products of conception, uterine discharges, vaginal mucus or milk together with serological evidence of active infection. S. dublin may be isolated when an active or a latent carrier cow aborts but in these cases an active infection will not be demonstrable. The retrospective identification of a case of S. dublin abortion may prove difficult as excretion of the organism is usually transient and the serum agglutinating antibodies frequently fall to low titres soon after the abortion.

Results obtained from 1887 sera using three serological tests for bovine brucellosis were compared with a serological classification of sera described as the ‘probable infection status’. Sera showing apparent false positive and apparent false negative reactions were identified, and were subjected to supplementary testing as appropriate.

The serum agglutination test (SAT) gave 35% apparent false negative reactions and 5% apparent false positives. The complement fixation test (CFT) gave 12% apparent false negative reactions using warm fixation (CFTW) and at least 5% using cold fixation (CFTC). The routine diagnostic system used in Victoria, in which the CFTW is supplemented by the CFTC and the SAT, gave 9% apparent false negative reactions and 2% apparent false positive reactions. The radioimmunoassay gave 1% or 6% apparent false negative reactions, depending the minimum diagnostic value used.

Atypical reactions in the CFT sometimes caused difficulties in diagnosis.

The properties of 5-p-chlorophenyl silatrane as a rodenticide against Rattus norvegicus and Mus musculus were investigated in the laboratory. The high oral toxicity of the compound was confirmed. When the compound was given to laboratory rats and mice by stomach tube at lethal dosages, signs of poisoning were observed within a minute. When caged wild rats and mice were given a choice between plain and poisoned baits the optimum rodenticidal concentration in the bait was about 0.5% for both species, producing 50% mortality in wild rats and 95% mortality in wild mice. The results are discussed in relation to safety in use and the probable effectiveness of the compound as a rodenticide in field conditions.

1. A technique for comparing the spermicidal powers of pure substances is described in detail. It is hoped that this may be accepted as the standard technique for the purpose.

2. The killing concentration of each substance is determined by this technique. The killing concentration is defined as the lowest concentration, in the series 2, 1, ½, ¼ per cent., etc., which suffices to kill every guinea-pig sperm suspended in glucose-saline solution in half an hour at the temperature of the body in four consecutive experiments, the majority of the control sperms being moderately or very active.

3. 36 substances have been graded by this technique.

4. Mercuric chloride and formaldehyde were found to be the most spermicidal substances. The killing concentration of each per cent.

5. Hexyl resorcin kills at per cent., soaps at per cent.

6. Formaldehyde and hexyl resorcin, among other substances, seem likely to be useful as contraceptives.

7. The significance of the high spermicidal power of soaps is discussed.

8. Quinine bisulphate and chinosol, which are perhaps more commonly used as contraceptives than any other substances, only kill at ½ per cent.

9. Certain very poisonous substances have very slight spermicidal powers. This applies to potassium cyanide, prussic acid and strychnine hydrochloride.

10. Foaming mixtures, consisting of acids and sodium bicarbonate, could probably be used alone as contraceptives.

11. The acrosome is the part of the sperm most vulnerable to spermicides. It tends to swell up and burst.

12. Sperms are very susceptible to changes in osmotic pressure.

13. It is the hydrogen ions and not the anions of acids that kill sperms.

14. The suggestion that tribasic acids would be found to be more spermicidal than dibasic, and dibasic than monobasic, is not substantiated.

15. Substances which reduce surface tension are often effective spermicides.

16. The characters of the ideal chemical contraceptive are discussed.

17. The need for co-operation in research in chemical contraception is stressed.

This study assesses governments' long-term non-pharmaceutical interventions upon the coronavirus disease 2019 (COVID-19) pandemic in East Asia. It advances the literature towards a better understanding of when and which control measures are effective. We (1) provide time-varying case fatality ratios and focus on the elderly's mortality and case fatality ratios, (2) measure the correlations between daily new cases (daily new deaths) and each index based on multiple domestic pandemic waves and (3) examine the lead–lag relationship between daily new cases (daily new deaths) and each index via the cross-correlation functions on the pre-whitened series. Our results show that the interventions reduce COVID-19 infections for some periods before the period of the Omicron variant. Moreover, there is no COVID-19 policy lag in Taiwan between daily new confirmed cases and each index. As of March 2022, the case fatality ratios of the elderly group in Japan, Hong Kong and South Korea are 4.69%, 4.72% and 1.48%, respectively, while the case fatality ratio of the elderly group in Taiwan is 25.01%. A government's COVID-19 vaccination distribution and prioritisation policies are pivotal for the elderly group to reduce the number of deaths. Immunising this specific group as best as possible should undoubtedly be a top priority.

A prevalence survey of methicillin-resistant Staphylococcus aureus (MRSA) was performed in 2010 in 19 long-term care facilities in Luxembourg. Of the 954 participating residents, 69 (7·2%) were colonized by MRSA. Previous history of MRSA [odds ratio (OR) 7·20, 95% confidence interval (CI) 3·19–16·27], quinolone therapy in the previous year (OR 2·27, 95% CI 1·17–4·41) and ⩾24 h care administered per week (OR 4·29, 95% CI 1·18–15·56) were independent risk factors for MRSA colonization. More than 75% of strains were of clonal complex (CC)5, mainly spa-type t003 or sequence type (ST)225 and ST710, which is a rapidly emerging lineage prevalent in central Europe. Five residents were colonized by livestock-associated genotypes belonging to CC398. Previously dominant CC8 strains have recently been replaced by more resistant CC5 strains in Luxembourg.

The object of the Swedish Antarctic Expedition was to conduct researches relating to the geography and natural history of the Antarctic regions south of Cape Horn. The expedition was to start from Sweden during the autumn of 1901. On the approach of the Antarctic winter, in February or March 1902, some of the party were to be landed in a suitable place in the Antarctic regions, with the object of wintering there. The members remaining on board the ship “Antarctic,” were to carry on investigations in the regions around Cape Horn, the Falkland Islands and South Georgia. The next summer, i.e. in December 1902 or January 1903, the ship was to return in order to pick up the wintering party at their station; and, thus reunited, the whole expedition was to go back to Sweden, where, as we had calculated, we should arrive in the spring of 1903.

Experiments on the bactericidal action of ultra-violet light have been made to determine the shape of the survival curve and the dependence upon radiation intensity of the rate of death. Bact. coli, Bact. prodigiosum and spores of B. mesentericus were irradiated with approximately monochromatic light of wave-length 2537 A. The survival curves obtained were exponential and the rate of death was accurately proportional to the intensity over an intensity range of 500:1.

By comparing these results with data previously obtained of the action of X-rays on the same organisms it was established that one ionization produced by X-rays is as effective as some hundreds of ultra-violet quanta. This is interpreted to mean that the quantum yield in whatever chemical change leads to the loss of viability in the irradiated bacteria is, for 2537 A., between 0·01 and 0·001.

1. All tests of spermicidal power are done with human semen at 37° C.

2. The total spermicidal power of pure substances and commercial products is measured by a test which is not intended to represent natural conditions very closely, but which gives consistently reliable results. The activity of the sperms is determined at 5 and at 30 min.

3. A commercial product of high total spermicidal power may be useless on account of the slow rate of diffusion of the spermicide out of the vehicle. A special test measures the rate of diffusion. This test is designed to represent natural conditions as well as is possible in the laboratory. The test is made as stringent as possible by avoiding mechanical mixture of the product with the semen. The activity of the sperms is determined at 2, 5, 15, 30, 60, 120, and 180 min.

4. The rate of disintegration and acidity or alkalinity of commercial products is measured.

5. The pathological test consists in inserting one-half the prescribed dose of a commercial product into the vagina of a bitch daily (except Sundays) for a fortnight, and then sectioning the vagina and examining microscopically.

6. A method is described whereby the pH of human semen may be determined colorimetrically rather accurately.

7. The average ejaculate of the human semen we have studied, from 13 donors, measures 3·9 c.c, contains 461 million sperms, and requires 3·1 c.c. of N/100 HCl to neutralize it.