A transportable surgery cross-flow unit has been tested under ‘operational conditions’. By the use of artificial aerosols and a volunteer surgical team, or dummies, it was found that, at an air velocity of 0·45 m./sec., a detectable transfer to above the table occurred only when quite highly concentrated aerosols (of more than 103·6 bacteria/m.3 of air or more) existed underneath the table. The short disappearance time under these conditions and the quite stable flow pattern above the table found when a surgical team was working, standing along both sides of the table, make it unlikely that an aerosol of detectable concentration can develop during surgery, at this site. The chance that particles, liberated from the heads of the surgical team, settle on the table, was found to be strongly reduced when a cross-flow tunnel operated at an air velocity of 0·45 m./sec. The transfer from outside the unit to the inside was prevented by closing the upper part of the open front side.

A large outbreak of streptococcal sore throat in a Royal Air Force Training Camp resulted in five cases of rheumatic fever among the 16- to 18-year-old apprentices, and one case in a 33-year-old airman. The most prevalent type of group A streptococcus isolated from throat swabs was M-type 5 and there was serological evidence that at least four of the rheumatic fever (R.F.) cases were due to this type.

Among the patients with uncomplicated throat infection the anti-streptolysin O (ASO) and anti-deoxyribonuclease B (anti-DNAase B) responses were in general rather low, even where there was evidence of protective antibody against type 5. However, a combination of the results of the ASO and anti-DNAase B tests gave an estimate of the extent of streptococcal infection 15–25% higher than did either test alone.

The titres of antibody to M-associated protein (MAP) were ≥ 60 in all the r.f. patients, and in about 50% of the other patients with ASO titres ≥ 200. This figure is unusually high compared with data from several other outbreaks of streptococcal infection due to different serotypes and also greatly exceeds comparable figures for cases of sporadic sore throat and acute glomerulonephritis.

This paper describes the epidemiologically relevant events that took place in a dairy herd infected by Salmonella dublin. The evidence presented indicates that it may be possible to eliminate infection from the farm and that residual infection or persistent excretion are uncommon. In two animals infection persisted, in one instance in the tonsil and in the other in the gall bladder. In this latter case the infection remained from the neonatal period until adulthood. It is possible that both these animals are relevant in a more general context and are indicative of the source of infection in outbreaks in which the origin of infection cannot be deter-mined by more routine examinations.

A number of serological tests were evaluated in a study of Salmonella dublin infection in a dairy herd. None of the tests used detected either of the two carrier animals from which Salmonella dublin was isolated at slaughter 7 and 17 months after the herd infection. The complement fixation tests used proved to be a better guide to the presence of recent herd infection than the conventional ‘0’ or ‘H’ agglutination tests.

Mice given an intraperitoneal injection of 0.5 mg. Corynebacterium parvum (dry weight) before vaccination with heat-killed (HK) or acetone-killed (AK) Salmonella typhimurium vaccine and later challenged intraperitoneally with S. typhimurium strain 1566, showed a statistically significant increase in mortality when compared with mice that had received only C. parvum but no vaccine. They also showed a higher mortality rate than mice receiving only HK or AK vaccine or mice that had received no vaccine before challenge. Prior administration of C. parvum to mice that are vaccinated with HK or AK vaccine appears to make them more susceptible to an intraperitoneal challenge with S. typhimurium. This was more apparent with HK vaccine than with AK vaccine.

Four calves were infected with 2·4 × 108S. dublin and penned separately. Fluctuations in environmental temperature did not affect the symptoms of the disease or the duration of excretion. Faecal samples were superior to rectal swabs for detecting excretors.

After transport stress, Salmonella was isolated from several organs at slaughter in an excreting calf, and uninoculated control calves became cross-infected. During slaughter, carcasses became contaminated on their surfaces. From one contaminated carcass Salmonella was recovered after chilled storage at 0° C. for 1 week and also after freezing at − 20° C. for 1 month.

When a standard sample of a simulated exudate containing known numbers of anaerobic bacteria was taken up on a swab and plated on solid medium, the number of colonies subsequently cultured represented a very small proportion of the original sample. Evidence is produced that the apparent loss is not primarily attributable to inactivation on the swab but rather to retention of organisms on the swab. This was demonstrable with Clostridium welchii and with Bacteroides species that have hitherto been regarded as relatively oxygen-sensitive.

When stock strains of Bacteroides species were held for some hours on swabs, some progressive loss of viability was demonstrable. A measure of protection was afforded when these organisms were held aerobically on blood agar medium, but a very exacting anaerobe and some wild strains of faecal anaerobes showed gradual inactivation under these conditions.

These findings may have important implications in relation to currently employed bacteriological sampling procedures with swabs in clinical practice.

The sera of 200 Chinese adults recently immigrated to Canada from Hong Kong were examined for antibodies to Toxoplasma gondii by the indirect fluorescent antibody technique. It was found that the total incidence was 18·0%. This is significantly lower than that of the indigenous population of the same age groups in this area.

Calves with a serum ‘H’ titre of 1/160 developed a chronic form of salmonellosis after infection with S. dublin. Their growth rate was severely retarded by this illness. An aerogenic strain of S. dublin was found to be much more virulent than an anaerogenic strain. Faecal samples were superior to mouth swabs in detecting animals carrying S. dublin.

During transport two uninoculated calves became infected and after transport stress, latent carriers of S. dublin with faecal samples negative for Salmonella for 5 weeks, restarted excretion. At slaughter Salmonella were isolated from viscera and organs and from the surface of five of six carcasses.

The purpose of this work was to study the effects of interrupted, continuous and post-salmonella inoculation treatment with furazolidone in the feed on the colon-ization of Salmonella infantis in the intestines of chickens, as well as the influence of furazolidone in vitro on the effect of a mixed culture used for the prevention of salmonellosis in chickens.

It was shown that chickens given interrupted treatment with 0·01% furazoli-done had significantly more salmonellas in the caeca than either chickens fed continuously with this drug or chickens without any treatment. The use of 0·01% furazolidone after inoculation with Salmonella infantis had no effect on Salmonella infantis in the caeca of chickens.

The mixed bacterial culture from the normal intestinal flora lost its preventive effect on salmonellosis when cultured with 0·01% furazolidone.

In the province of Voyvodina 18 cases of post-vaccinal encephalitis have been recorded, three of which were fatal.

The estimated morbidity rate was 0·6 per 105 after revaccination, and 3·9 per 105 after primary vaccination. The virological studies described, as well as other findings referred to in this report, are consistent with the possibility of an autoimmune aetiology of the post-vaccinal encephalitis cases observed.

The relative susceptibility of VERO cells and primary rhesus monkey kidney cells to 47 prototype strains of human enteroviruses is described. Of these strains, types 4, 14, 16, 17, 18, 21, 31 and 34 and Coxsackie virus A 9 failed to cause CPE in the VERO cells whilst only one, echovirus type 34, failed to cause CPE in the monkey kidney cells.

A comparison is given of the efficiency of the two cell cultures for enterovirus isolation from clinical material. Results show that VERO cells are as useful as primary monkey kidney for the isolation of Coxsackie B viruses but less satisfactory for isolating echoviruses. They are satisfactory for the isolation of single types of poliovirus and appear to be more satisfactory than primary monkey kidney cells for the isolation of mixtures of polioviruses. The identification of enteroviruses by neutralization tests in VERO cells is successful.

A series of meatal swabs, taken from 17 men over a period of 17 months during their tour at an Antarctic base was examined for mycoplasmas. The number of organisms isolated never exceeded 104 and not every specimen from each man yielded mycoplasmas. Nevertheless, Mycoplasma hominis was isolated from 71% and T-mycoplasmas from 59% of the men at some time during their stay. M. hominis persisted in the presence of serum IHA antibody titres of 1/64. Three subjects yielded only M. hominis and one only T-mycoplasmas.

Six men had already spent a year at the base when the study began and myco-plasmas were still being isolated from some of them at the end of a 31 month period of isolation. The persistence of mycoplasmas in the male genital tract can therefore be independent of sexual contact. Two modes of persistence are suggested; either a few men act as carriers and reinfect the others by contaminating their environment, or as seems more likely, most men have chronic infections.

Guanidine hydrochloride selectively inactivated both the biological activity and the immunogenicity of the haemagglutinin of influenza A/X-7 (H0N2). The residual neuraminidase was fully active biologically and immunologically. The reverse was observed with influenza B/ROB; with this virus the haemagglutinin was resistant, and was immunogenic; while the neuraminidase was selectively inactivated, and was not immunogenic.

Revaccination between 2 and 5 years after the last vaccination induced higher complement-fixation titres than revaccination 7–63 years after the last vaccination. The highest CF titres were reached during the 3rd to the 5th week after vaccination.

Fifty-two serum samples, taken 137 or more days after a successful vaccination, all showed CF titres lower than 1/2.

In a group of successfully vaccinated persons with no post-vaccinal complications, 65 out of 66 had a successful ‘take’ after one or two subsequent vaccinations.

Sera of persons receiving primary vaccination showed significantly lower CF titres than sera of revaccinated persons. Cases of post-vaccinal encephalitis showed greater antibody response than uncomplicated successfully vaccinated cases in both the primary vaccination and revaccination groups. The antibody response in revaccinated persons with post-vaccinal encephalitis was greater than that in the group of successfully revaccinated cases without encephalitis.

A group of 26 naturally hyporeactive persons completely failed to ‘take’ even after vaccination repeated between 3 and 10 times (average 5 times per person). The frequency of seropositives in this group, and the height of their CF titres, were significantly lower than in the group of successfully vaccinated persons. These findings support the view that untreated persons who repeatedly fail to ‘take’ with the vaccine must not be considered immune.

In vaccinated persons treated with immunoglobulin (with or without simultaneous treatment with Marboran) antibody production was apparently diminished. Treatment of patients with Marboran significantly lowers the capacity of the vaccine to ‘take’.

In the examination of bovine fetal material it was found that there was a significant increase in the proportion of mixed infections identified as the time between abortion and the collection of the samples increased. Examination of paired serum samples from abortions from which only Corynebacterium pyogenes was isolated revealed evidence of active infection in two-thirds, suggesting that C. pyogenes may have been acting as a primary abortifacient in these cases.

An epidemic of acute haemorrhagic conjunctivitis occurred in Morocco in 1970–1. It was caused by an enterovirus which appeared to be a new antigenic type similar to a virus isolated in South East Asia during the same period.

An attempt was made to sterilize a newly erected building of approximately 1200 m.3 (43,000 ft.3), specially designed for the breeding of specific-pathogen-free mice, rats and guinea-pigs. Two methods of treatment were used, namely an ampholytic surface acting biocide/formaldehyde aerosol followed after 2 days by formaldehyde vapour. Bacteriological examination was made of 100 sites in the animal rooms, staff quarters and general service area before and after both treatments. Identification of the bacteria isolated was based upon their morphological appearance on laboratory media incubated aerobically and their reaction to Gram's stain. Organisms were isolated from 72/100 sites before treatment, from 50 sites after the first treatment, and from 13 sites after the second treatment. The bacteria that survived both treatments were of several species.

With the use of streptomycin-resistant mutants to facilitate recovery, 5 strains of 4 species of Salmonella were shown to grow rapidly at 22° C. on low salt ham even from an inoculum of 10–20 organisms. S. pullorum did not grow well. All 6 strains of Salmonella survived but did not grow on ‘high salt ham’. We conclude that cooked ham containing approximately 2·8 g. NaCl/100 g. H2O once infected is more likely to give rise to food poisoning than is ham with the higher salt content traditionally used.

The air from a house and garden in a rural area has been sampled and the size distributions of the airborne particles have been determined. The particle concentrations are shown to be generally higher indoors. Changes in the particle concentration during various activities in a small room have been shown to be greatest for particles larger than 3 μm. diameter. Stereoscan microscopic observation has shown that many of the airborne particles in rooms and some from those in outside air appear to be scales of desquamated skin. The presence of protein in many of these particles complements the microscopic observations.