An indirect fluorescent antibody test was used to detect the presence of Streptococcus suis type 2 in nasal and pharyngeal swabs taken from pigs in Papua New Guinea. The rate of carriage for the two sites in domesticated indigenous village pigs was 0·5 and 2·5% respectively, compared to 39 and 43% for intensively reared pigs. These findings were supported by the results of a serological survey, using an enzyme linked immunosorbent assay, in which 87% of intensively reared pigs but only 8% of village pigs were seropositive to S. suis type 2.

It is proposed that in intensive piggeries S. suis type 2 is continually cycled between pigs. In village pigs, the low population density and harsh environmental conditions prevents this cycle of infection.

Highly purified influenza virus was degraded using anionic and non-ionic detergents. Best results were obtained using the non-ionic detergent Triton N101. Tests showed that virus extracts contained neuraminidase and a substance that reacted specifically with rabbit antibody to virus haemagglutinin (specific serum blocking substance). Haemagglutination-inhibiting antibody was produced when virus extracts were inoculated into guinea-pigs. Immunodiffusion tests showed that extracts were complex. Host-specific material was regularly found. Under appropriate conditions S-antigen was detected as a single line pattern component. Two or more virus-specific materials were also present. One of these was probably neuraminidase and the other the specific serum blocking substance.

In the incidence patterns of cholera, diphtheria and croup during the past when they were of epidemic proportions, we document a set of cycles (periods), one of which was reported and discussed by A. L. Chizhevsky in the same data with emphasis on the mirroring in human disease of the ∼11-year sunspot cycle. The data in this study are based on Chizhevsky's book The Terrestrial Echo of Solar Storms and on records from the World Health Organization. For meta-analysis, we used the extended linear and nonlinear cosinor. We found a geographically selective assortment of various cycles characterizing the epidemiology of infections, which is the documented novel topic of this paper, complementing the earlier finding in the 21st century or shortly before, of a geographically selective assortment of cycles characterizing human sudden cardiac death. Solar effects, if any, interact with geophysical processes in contributing to this assortment.

By feeding monkeys on healthy rye, wheat and other cereal and leguminous seeds convulsive and paralytic symptoms similar to those of convulsive ergotism in man can be produced.

Large amounts of cold-water extracts of the grains given to monkeys per os may cause the symptoms acutely, just as large meals of rye bread have occasionally been reported to do in man.

Salts of phytic acid and decomposition products from it, isolated from all these grains and given to monkeys by the stomach or hypodermically, occassion symptoms exactly similar to those caused by feeding the grains.

The occurrence of poisoning when these grains are consumed as food is partly a question of the quantity consumed and partly a question of the ability of the consumer to break down in the bowel the poisonous phytates and so render them innocuous. If they are not fully broken down they are absorbed and act as poisons to the nervouse system.

The pathological lesions in the nervous system of monkeys are the same as those which are described as occurring in convulsive ergotism in man.

Convulsive ergotism is not a “deficiency” disease, nor is it ergot disease, but is caused by poisons normally present in rye and other grains.

The faecal-pat prevalence (as estimated by culture) of Campylobacter fetus from cattle and sheep on 19 farms in rural Lancashire was investigated using standard Campylobacter culture techniques and PCR during a 2-year longitudinal study. C. fetus was isolated from 9·48% [95% confidence interval (CI) 8·48–10·48] of cattle faecal pats and 7·29% (95% CI 6·21–9·62) of sheep faecal pats. There was evidence of significant differences in shedding prevalence between geographical regions; cows in geographical zone 3 had an increased risk of shedding C. fetus compared to cows in geographical zones 1 and 2 (OR 6·64, 95% CI 1·67–26·5, P = 0·007), as did cows at pasture (OR 1·66, 95% CI 1·01–2·73, P = 0·046) compared to when housed. Multiple logistic regression modelling demonstrated underlying seasonal periodicity in both species.

The following paper embodies the main facts obtained during a prolonged investigation as regards the pollution of Tidal Waters and of Shell Fish, undertaken on behalf of the Royal Commission on Sewage Disposal.

Infant mice were used for the evaluation of the efficacy of bismuth subaslicylate (BSS) in the prevention the growth of Campylobacter jejuni in the intestine. The MIC90 of ten C. jejuni strains was 900 μg/ml. Of three dosage regimens tested, continuous treatment before and after the bacterial challenge, mimicking the way BSS is used in the prevention of traveller's diarrhoea, was the most effective. Growth inhibition was dose dependent; the high dose of 2000 μg per day was more effective than 300 μg per day. After cessation of treatment, campylobacter counts increased to the same level as in the control animals.

The purpose of this study was to examine whether certain salmonella serovars, other than Typhi and Paratyphi, may have an increased ability to enter the human body fluids. The data are based on over 20000 salmonella isolated from humans during 1984–9, among them 436 from extra-intestinal (EI) sources. The mean percentage of EI salmonella isolated in Israel (excluding Typhi and Paratyphi), was 2·1 %. In three serovars: S. 9, 12:1, v:-, Virchow and Saintpaul, the percentage of blood isolations and of EI isolations in general, was high. Among the frequent serovars, ser. Infantis and Hadar had a much lower percentage of EI isolations.

Acute poststreptococcal glomerulonephritis (APSGN) is an inflammatory kidney condition that can complicate Group A streptococcal infections. Two clusters of APSGN occurred recently in New South Wales (NSW), Australia; one in a rural town in December 1999 and the other in a Sydney suburb in January 2000. We interviewed carers of the affected children but found no common exposures except three of the Sydney cases were cousins in frequent contact. To assess the probability of these clusters occurring, we analysed hospital admissions for acute glomerulonephritis, as a proxy for APSGN in younger patients. The incidence of acute glomerulonephritis in NSW during 1989/90–1997/8 in residents aged under 20 years was 2·2/100000/year (95% CI 2·0–2·5). Incidence was highest in children aged 5–9 years, boys and Aboriginal children. We found no evidence for other clusters during that period. The recent clusters highlight the continued potential for unexpected future outbreaks of APSGN.

This study demonstrates a very high prevalence of antibodies to hepatitis C virus among Icelandic intravenous (i.v.) drug users. Of 152 identified i.v. drug users 95 (63%) were shown to have antibodies to the hepatitis C virus. In contrast the seroprevalence in the general Icelandic population is low, (0·2%). Almost all cases of hepatitis C virus infection in Iceland are due to i.v. drug use or to use of infected blood or blood products. Sporadic cases with unexplained modes of transmission, a significant portion of hepatitis C infections elsewhere, are virtually non-existent in Iceland. The results of this study are consistent with the hypothesis that the sporadic community-acquired cases could be caused by blood transfer due to bites from insect vectors such as mosquitoes which are not found in Iceland.

1. In the course of the examination of sputum from cases of lobar pneumonia, observations have been made on the incidence of the chief types of pneumococci. In the district from which the material was obtained, there was an apparent local diminution in the number of cases of lobar pneumonia due to Type II; the figures were 32·6 per cent. of Type II cases in the period 1920–22, and only 7·4 per cent. in the period 1924–27. The incidence of Type I was approximately the same in the two periods, the percentages being 30·6 and 34·3.

2. Several different serological varieties of pneumococci have been obtained from the sputum of each of several cases of pneumonia examined at various stages of the disease. This has occurred most frequently in cases of pneumonia due to Type I, and in two instances four different types of Group IV were found in addition to the chief types. The recovery of different types is facilitated by the inoculation of the sputum (preserved in the refrigerator), together with protective sera corresponding to the various types in the order of their appearance.

3. Two interesting strains of Group IV pneumococci have been obtained from pneumonic sputum.

One was an R strain which produced typical rough colonies, yet preserved its virulence for mice and its capacity to form soluble substance. This R pneumococcus developed a large capsule in the mice, which died of a chronic type of septicaemia. A strain producing smooth colonies was obtained from it in the course of a prolonged series of passage experiments.

The second strain, which was proved not to be a mixture, agglutinated specifically with the sera of two different types. In the peritoneal cavity of the mouse the specific soluble substance of each type was produced.

4. A method of producing the S to R change through ageing of colonies on chocolate blood medium containing horse serum is described. After two to three days' incubation small rough patches appear in the margins of the smooth colonies, and from these pure R strains can be isolated.

5. It has been shown that the R change is not equally advanced in the descendants of virulent pneumococci which have been exposed to the action of homologous immune serum. Some R strains form traces of soluble substance in the peritoneal cavity of the mouse; these revert readily to the virulent S form and, in addition, are able to produce active immunity. Others show no evidence of S antigen; spontaneous reversion takes place with difficulty, if at all, and they are incapable of producing active immunity. The stronger the immune serum used, the more permanent and complete is the change to the R form.

6. Restoration of virulence to an attenuated R strain, with recovery of the S form of colony and of the original serological type characters may be obtained by passage through mice. The change from the R to the S form is favoured by the inoculation of the R culture in large doses into the subcutaneous tissues; but the most certain method of procuring reversion is by the inoculation of the R culture, subcutaneously into a mouse, together with a large dose of virulent culture of the same type killed by heat.

Incubation of such a mixture in vitro does not induce reversion.

7. Reversion of an R strain to its S form may occasionally be brought about by the simultaneous inoculation of virulent culture of another type, especially when this has been heated for only a short period to 60° C., e.g. R Type II to its S form when inoculated with heated Type I culture.

8. Type I antigen appears to be more sensitive to exposure to heat than Type II antigen, since the former loses the power to cause reversion when heated to 80° C, whereas Type II culture remains effective even after steaming at 100° C.

9. The antigens of certain Group IV strains appear to be closely related to that of Type II, and are equally resistant to heat. Steamed cultures of these Group IV strains cause the R form derived from Type II to revert to its S form, while they fail to produce reversion of the R form derived from Type I.

10. The inoculation into the subcutaneous tissues of mice of an attenuated R strain derived from one type, together with a large dose of virulent culture of another type killed by heating to 60° C., has resulted in the formation of a virulent S pneumococcus of the same type as that of the heated culture.

The newly formed S strain may remain localised at the seat of inoculation, or it may disseminate and cause fatal septicaemia.

The S form of Type I has been produced from the R form of Type II, and the R form of Type I has been transformed into the S form of Type II.

The clear mucinous colonies of Type III have been derived both from the R form of Type I and from the R form of Type II, though they appear to be produced more readily from the latter. The newly formed strains of Type III have been of relatively low virulence, and have frequently remained localised at the subcutaneous seat of inoculation.

Virulent strains of Types I and II have been obtained from an R strain of Group IV.

11. Heated R cultures injected in large doses, together with small doses of living R culture have never caused transformation of type, and only rarely produced a reversion of the R form of Type II to its virulent S form.

12. The results of the experiments on enhancement of virulence and on transformation of type are discussed and their significance in regard to questions of epidemiology is indicated.

The lysis of Bacterium coli suspensions brought about by glycine shows the following characteristics:

(1) There is a latent period of 2 hr., followed by a rapid lysis reaching a maximum in about 8 hr.

(2) The extent of the lysis is independent of the dilution of the bacterial suspension over a wide range.

(3) The extent of the lysis increases with the glycine concentration up to 10M, but is approaching a limit at this concentration.

(4) The lysis is negligible below pH 5 and above pH 10, and shows a maximum rate in the region of pH 6–5–8–5.

(5) The rate of lysis has a very high temperature coefficient (Q10 of the order of 5).

Techniques for the production of experimental pneumonia are briefly reviewed. A new method of intra-oral inoculation in the anaesthetized mouse is described and its advantages with particular reference to the danger of aerial contamination and facility of technique discussed. An application of this method to virulence studies is indicated and other possible applications suggested.

The author would like to express gratitude to Dr I. Friedmann for having made this work possible and for his advice and help at all stages. He would also like to thank the late Sir E. L. Kennaway, Dr F. Fulton and Dr D. A. Osborn for helpful suggestions, Prof. E. T. C. Spooner for the kind loan of the Bourdillon apparatus, Dr S. T. Cowan for an N.C.T.C. strain of Klebsiella, Mr P. Payne for statistical advice and Mr D. Connolly for the photomicrograph.

A retrospective cohort study was conducted to quantitate the relationship between neutropenia and rates of clinical bacteraemia among adults with HIV infection receiving medical care at one institution between 1991–5. The primary exposure, absolute neutrophil count (ANC), was summarized as mean ANC within a given week, using a five-level stratification (reference > 1000/μl). ANC stratum-specific rates of bacteraemia were calculated, by organism type. Linear trend tests were performed to assess dose-response relationship between neutropenia and rates of bacteraemia. The cohort included 1645 patients contributing 26785 patients-weeks and 191 episodes of bacteraemia. The unadjusted effect of neutropenia was most evident for bacteraemia due to E. coli (RR 3.4), Klebsiella pneumoniae (RR 16·7), and P. aeruginosa (RR 10.4). For bacteraemia due to any of these three organisms (47 episodes), with reference ANC > 1000/μl, relative rates were: 751–1000/μl, 1·12; 501–750/μl, 2.11; 251–500/μl, 13·58; 0–250/μl, 21·89.

(i) The theory of amoebic surveys and of related types of pathological surveys is discussed.

(ii) An inequality is derived,

where X is the total number of carriers and X1, X2 are the new carriers found at the first and second examinations.

(iii) Demonstrability is defined and several theoretical distributions of it are considered.

(iv) Demonstrability is shown not to be a constant in the populations considered.

(v) The danger of extrapolation is noted.

(vi) Life-table methods are introduced to treat some well-known published series.

(vii) A criterion for the adequacy of any estimate of the total carrier rate is given. The mean demonstrability of the outstanding carriers after successive examinations must form a decreasing series.

(viii) This criterion usually shows that the method of estimating the carrier rate for Entamoeba histolytica as three times the proportion of positives at a single examination, or as the total number of positives picked up in six examinations, both give too low a carrier rate.

(ix) It is suggested that the investigation of the ‘carrier’ rate may in certain cases be merely a measure of ‘demonstrability’.

(x) Possible future lines of investigation of the problem are noted.

Investigations were conducted between 1977 and 1979 to assess the performance of microbiological tests for detecting and identifying residues of therapeutic-type antibacterial substances in meat and offal. Of the 5442 home-produced meat samples examined, 34 (0·63%) showed inhibitory activity in the screening test, which used Bacillus subtilis BGA and Micrococcus luteus as indicator organisms. Identification by electrophoretic and thin-layer chromatography/bio-autography techniques confirmed that only two of the 34 screen failures were due to true antibacterial residues: a pig sample contained a trace of penicillin and a horse sample contained a trace of an incompletely identified substance resembling a tetracycline. Twelve of the other 32 failures in the screen test were due to naturally produced inhibition and were, thus, falsely positive, whilst the remainder were shown to be negative. All of the 85 (8·7%) screen test failures from the 972 imported meat and offal samples tested were falsely positive. Additional samples from certain animals known to have been given antibiotic treatment were tested concurrently to give a more searching indication of screen and identification test efficacy.

1. Coramine increases the sensitivity of the central nervous system, particularly the centres situated in the medulla.

2. In large doses, Coramine increases the activity of the spinal cord, producing muscular twitchings of the limbs and body which, when severe, take on the character of convulsive movements.

3. There is a wide margin of safety between the therapeutic and lethal doses.

4. Lethal doses produce convulsions and respiratory failure owing to the involvement of the muscles of respiration.

5. Coramine acts as a powerful respiratory stimulant and is able to over-come the depressant effects of morphine on the respiratory centre in the medulla.

6. Small doses of Coramine raise the blood pressure which is due to a peripheral vasoconstriction. This is partly due to a stimulating effect of the drug on the medulla and to some extent to a peripheral action on either the vasoconstrictor nerves or the arterial muscle. Slightly larger but moderate doses sometimes cause a primary relaxation of the arterioles lasting a few seconds, which may cause a small short-lived fall in blood pressure which is never serious in the normal animal. The rise in blood pressure may last ¼–2 hr., according to the dosage employed.

7. Small amounts of Coramine may increase the amplitude and stroke volume of the heart. This effect was never constant. Larger but moderate doses always produced a diminution in cardiac stroke volume with a decrease in cardiac output. The same effect is seen when large doses are employed. This appears to be the cause of the prolonged lowering of the blood pressure following the administration of large doses of Coramine.

8. Coramine dilates the coronary vessels of the myocardium producing an increase in coronary flow.

9. Coramine lowers the pressure in the right auricle of the heart and the pulmonary artery.

10. Coramine has no effect upon intestinal movements except, when large doses are employed, it causes a slight diminution in the amplitude of the movements with a small increase in muscular tone.

Three groups of post-vaccination sera were studied for vaccinial antibody by precipitation, haemagglutinin-inhibition, complement-fixation and neutralization tests. All sera were negative by precipitation and many by haemagglutinin-inhibition and complement-fixation tests, but most showed neutralizing activity at serum dilutions of 1/10 or higher. The differences in antibody titres between the three groups of sera were most probably related to the past history of revaccination.

This investigation was supported in part by Public Health Service Grant AI–1632–16 VR from the National Institute of Allergy and Infectious Diseases, by the World Health Organization and by the Marcus T. Reynolds III Fund.

A simple method of breeding large numbers of rabbit fleas in a rabbit house with minimal disruption to the general routine is described.

A composite microporous membrane made of poly(N-benzyl-4-vinylpyridinium chloride) that showed strong affinity with bacterial cells was prepared as a filter material for removing airborne bacteria. Thickness, pore diameter and porosity of the membrane were 0·72 mm, 14·5 μm and 63%, respectively. Electron micrographic analysis revealed that the membrane consisted of a very large number of connected beads of 1·4 μm in diameter made of the pyridinium-type polymer. Filtration using the membrane was performed easily at low flow rates with insignificant pressure drop across the membrane. Filtration at 63·7 cm/sec gave 99·98% and 99·996% removal (3·7 and 4·4 log10-unit reduction in concentration) of Escherichia coli and Pseudomonas aeruginosa, respectively. Staphylococcus aureus was not detected in filtrates. Since pores of the membrane were much larger than these bacteria, the efficient removal was best explained in terms of the affinity of the polymer with bacterial cells.