Observations on the bacteriological contamination of the air have been made in an operating room fitted with three alternative systems of ventilation.

These were; A, downward displacement ‘piston’; B, moderate velocity turbulent; C, low velocity turbulent.

The volume of the ventilating air supplied was the only characteristic of the ventilation which affected the contamination levels reached during operations. No significant differences could be detected between the three ventilating systems in this respect.

Unavoidable temperature differences in the operating room render it generally impossible to produce effective downward displacement air movement with ventilating air supplies which do not exceed 1500 ft.3 per minute over a ceiling area of 300 ft.2.

Great differences were observed between the several carriers of Staphylococcus aureus in the extent to which they dispersed this organism into the air when working in the operating room.

A survey of mild respiratory disease in a primary school was undertaken over a 2-year period to determine which of the newer respiratory viruses were responsible for these illnesses.

The over-all isolation rate was low but a wide variety of viral agents was isolated.

None of these caused epidemics but it is suggested they may be the cause of a low but constant absentee-rate throughout the year.

1. A marked sex variation in susceptibility to warfarin was found in 6-month old L.A.C. Grey mice, males being more susceptible than females. No sex difference in response was evident in young mice 6 weeks old.

2. Susceptibility to warfarin poisoning increased markedly with age in males but not in females.

3. No significant increase in mortality following warfarin poisoning occurred in adult female mice given methyl testosterone.

Preliminary typing of 1820 strains of Staph. aureus from 51 herds with the human set of phages showed that non-typable strains were common (31·4%). Other phages were investigated and 1404 strains from 328 herds were typed with 42 phages; these included the human phage set, phages from Weybridge and phages isolated in Brisbane. The following 20 phages were selected as suitable for typing bovine strains of Staph. aureus in Australia: 29, 80, 13, 71, 6, 7, 42E, 47, 53, 77, 31B, 42D, 81, 101, 102, 107, 110, 600, 367, 425. Phages 13, 367, 425, 600 were from Brisbane and 101, 102, 107 and 110 were from Weybridge.

Salmonellas were isolated from 278 of 800 (34·7 %) samples of frozen carcass or boneless horsemeat from South America and from 101 of 751 (13·5%) samples of frozen boneless beef. However, the percentage of contamination detected depends to a large degree on the method of examination. Contamination was mostly external, a fact which points to slaughterhouse contamination. Boneless meat was contaminated to a higher degree than carcass meat.

The air of a subdivided surgical ward was sampled by the exposure of culture plates for 12 hr. periods 5 days a week.

A number of ‘broadcasts’ of airborne Staphylococcus aureus were observed; many of these were of very short duration. A single person could be recognized as responsible for 22 of the 33 broadcasts; in all cases dispersal seemed to be from carrier sites rather than from infected lesions.

There was little spread of the staphylococci between the 4 rooms of the ward. The frequency of nasal carriage of tetracycline-resistant S. aureus increased from 6·2% in patients examined during their 1st week to 13·2% in those examined in their 4th week in the ward; the rate for all S. aureus declined from 31·3 to 26·4%.

It is suggested that the long-period exposure of culture plates for the collection of airborne staphylococci may be useful in monitoring some aspects of hospital hygiene.

Experimental infection of captive Common Terns with Influenza virus A/Tern/South Africa/1961 reproduced the disease seen in the 1961 epizootic during which Tern virus was originally isolated. Infected terns excreted virus in their droppings. At death a viraemia was present but immunofluorescent studies determined the sites at which virus reproduction occurred. A Swift Tern suffered no ill effect from the injection of Tern virus but developed HI antibodies. The role of migrant sea-birds in spreading avian influenza is briefly discussed.

Trials of aqueous and oil adjuvant vaccines in young adult volunteers showed that severe local reactions were rare. However, the incidence of minor symptoms was too high for a vaccine which requires to be administered repeatedly. In contradistinction to some reports, systemic and allergic reactions did not constitute a problem.

An outbreak of infection in a Premature Baby Unit due to a single strain of Pseudomonas aeruginosa is described. The outbreak lasted for 16 months, during which this organism was isolated from the faeces of 99/418 premature babies, many of them being symptomless carriers. There were seven deaths due to the infection. The source of the epidemic was not found. The main reservoir of infection was the babies' faeces. Though many full-term babies were symptomless carriers of the epidemic strain of Ps. aeruginosa, they were not ill.

Measures for control of the outbreak, and the aetiology of neonatal intestinal infection with Ps. aeruginosa are discussed.

Sera were obtained from about half of the Tristan da Cunha islanders on reaching Cape Town in October 1961, a few months after reaching Britain and before returning to the Island in 1963.

After vaccination against current influenza A 2 and B serotypes antibodies were evoked against earlier serotypes, in particular against influenza A1 of 1951 with which the islanders had almost certainly been infected. Those who failed to develop antibody against A 2 and B after vaccination developed it later presumably owing to natural infection.

Almost all islanders developed antibodies against parainfluenza 3 and 1 and some against parainfluenza 2 and coxsackie A 21 viruses. There were no antibody rises against reoviruses.

In trials with polyvalent commercial influenza vaccines the antibody responses to oil-adjuvant vaccine persisted longer and were often higher. Antibody conversion was poor after all vaccines and delayed after adjuvant.

The properties of naturally occurring poliovirus strains of each serotype have been studied using three marker tests: the R.C.T.40 test, intratypic serodifferentiation and, for type 1 strains only, inhibition by dextran sulphate.

The results show that while most strains resemble the prototype strain of the same serotype, considerable natural variation exists, especially in the ability to grow at temperatures between 39° and 40° C.

No correlation has been found between the results of the tests on individual strains and it is concluded that no single test is sufficient to characterize a strain.

The incidence of rinderpest infection in game animals in selected localities of South Kenya and North Tanganyika was studied during the period 1960 to 1963. Serum samples from 590 wildebeest (Connochaetes taurinus), 48 eland (Taurotragus oryx), 65 Thompson's gazelle (Gazella thompsoni) and 39 Grant's gazelle (Gazella granti) were tested for rinderpest neutralizing antibody.

Rinderpest infection was shown to have been very frequent in yearling wilde-beest in the Mara area of Kenya in 1959/60, in the Serengeti National Park of Tanganyika in late 1960 and also in the Serengeti, and some adjacent areas, during the latter half of 1961. In the Ngorongoro Crater in 1961 infection was far less widespread, with only 11% of the yearlings acquiring antibody, compared to 67% in the Serengeti. The infections in 1959 and 1960 were clinical epizootics, accompanied by a considerable mortality, whereas no overt disease was reported in the course of 1961. Eland were affected in a similar manner to wildebeest up to 1960 but only a low rate of serological conversion was demonstrated in 1961. Adult Thompson's gazelle showed a low rate (ca. 12%) of infection but no anti-body was detected in Grant's gazelle.

Only a small proportion of the wildebeest calves born in early 1962 acquired antibody by mid-1963 and this was due, at least in part, to infection late in 1962; it was not clear, unfortunately, whether the positive animals belonged entirely to resident, as opposed to migratory, groups. No clinical signs or mortality were reported in this year.

A low incidence of rinderpest infection in wildebeest was also demonstrated both before and after 1960 in the Kajiado district of Kenya, where disease of game has not been reported in recent years. It is possible that the positive animals, as also the 1962 cases in Tanganyika, acquired the virus from low-grade infections of cattle.

The transmission of rinderpest antibody from wildebeest dam to calf, presumably via the colostrum, was demonstrated regularly, except in six calves about 1–2 weeks old. No completely satisfactory explanation was obtained for their failure to acquire passive antibody but it may have been due to abnormal disturbance in the herds, associated with the shooting. The antibody titres in calves were initially higher than those in the serum of their dams but by the end of the 3rd month this position had been reversed. Individual calves became serologically negative from about the 10th week of life and all were devoid of antibody by the 6th to 7th month. The half-life of passively-acquired antibody was 4·4 weeks.

1. The methods used for clearing a vaccine substrain of 17 D yellow fever virus of contaminant avian leucosis viruses are described.

2. Tests in animals and human subjects showed that the characteristics of the virus remained unchanged.

Eighteen patients treated by tracheostomy and mechanical ventilation were studied in an attempt to determine whether contaminated ventilators could act as a source of Pseudomonas aeruginosa isolated from the respiratory tract. Twelve became infected. In seven instances it was possible to demonstrate prior contamination of the ventilator. Furthermore, eight of the patients had indistinguishable organisms on the basis of pyocine and phage typing, and six of the ventilators harboured the same organisms. The most likely explanation is cross-infection via contaminated machines.

Strains of poliovirus were obtained from 13 of the 18 persons in England and Wales with paralytic episodes after administration of oral vaccine in 1962. They have been studied using three marker tests: the R.C.T.40 test, intratypic serodifferentiation and inhibition by dextran sulphate. For comparison a number of strains from subjects with non-paralytic vaccine-associated reactions and from patients with paralytic poliomyelitis not related to vaccine were also tested.

Of the eight patients excreting type 1 strains seven came from South Wales where an outbreak was in progress. They all resemble naturally occurring strains from the outbreak in growing at 39·3° but not at 39·8° C.

Only one subject excreted type 2 virus which was of vaccine type.

The type 3 strains included a series from a family group where a range of results from vaccine to the wild range was obtained. Three other patients with vaccineassociated paralysis excreted type 3 strains with the characteristic of naturally occurring strains.

A micro-organism, previously known as the J agent, was grown on solid medium: its various characteristics suggested that it was a mycoplasma and it was provisionally named Mycoplasma suipneumoniae.

In the growth-inhibition and metabolic-inhibition tests, M. suipneumoniae was indistinguishable from M. hyopneumoniae (Maré & Switzer, 1965).

By the growth-inhibition test, M. suipneumoniae seemed unrelated to all of a wide range (42 strains) of other mycoplasmas examined. These results suggest that, if the similarity between M. suipneumoniae and M. hyopneumoniae is substantiated in further work, these latter two strains are probably a new species.

M. suipneumoniae was also identified by the metabolic-inhibition test, by precipitation in agar gel, and by immune-fluorescence. Using the last two methods, M. suipneumoniae was distinguished from a second porcine mycoplasma (strain 603).

The most important property of M. suipneumoniae is its ability to induce enzootic pneumonia experimentally in pigs.

Eight strains of Cl. welchii were studied for the heat-resistance of their spores. Spores of Cl. welchii isolated from food-poisoning cases had greater heat-resistance than strains isolated from soil or faeces. D-values and trend values were calculated from the thermal death curves.

A technique is described for the routine isolation of salmonellas from meat and bone meal samples used in animal feedingstuffs. The technique more than doubled the number of positives obtained by an orthodox method. Identical samples were used in the trial.

Impression plates from initially clean horizontal surfaces and floor areas in surgical wards showed a rapid accumulation of bacteria, mainly micrococci, which reached a fluctuating equilibrium after about 24 h. A later increase in bacterial contamination (mainly with aerobic sporing bacilli) to a higher equilibrium level after about 14 days occurred on uncleaned areas. Walls, even if left unwashed, acquired very few bacteria, but many were deposited locally when the wall was touched by a subject whose skin carried large numbers of staphylococci; moist exposed plaster was also heavily contaminated.

Regular use of a disinfectant (‘Sudol’ 1 in 100) in cleaning a ward floor did not reduce the equilibrium level of bacteria on the floor.

The transfer of staphylococci from contaminated to clean areas on the soles of shoes was demonstrated; the use of tacky and disinfectant mats did not appreciably reduce the transfer of bacteria by this route.

Staphylococci deposited on a wall by a disperser were shown to be transferred from the contaminated area of wall to the hands of another subject who did not previously carry the organism; this subject was shown to transfer the staphylo-coccus to a wall which he touched.

Attempts to redisperse by air movement Staph. aureus which had been shed by a disperser or by a contaminated blanket on to the floor surfaces had little effect; neither blowing with a hair dryer nor brisk exercise appeared to lift any of the staphylococci from a vinyl surface, and only small numbers were lifted by these measures from a terrazzo surface.

The hazards of infection from the inanimate environment are discussed.