Eight explosive outbreaks of food poisoning, occurring in school canteens in England during 1953 and affecting 1190 known cases, are described. The clinical features were characteristic of the toxin type of illness. No deaths occurred.

The food causing all of these outbreaks was prepared from spray-dried skim milk powder. It was not subsequently heat-treated and was usually consumed 3–4 hr. after preparation.

The spray-dried milk powder proved to contain a high content of bacteria, including large numbers of Staph. aureus, of a phage pattern often associated with food poisoning. The assumption was therefore made that these outbreaks were caused by staphylococcal enterotoxin.

Because the food was often consumed within 3–4 hr. of reconstitution of the milk powder—before, in fact, the staphylococci had had time to grow—it is concluded that the poisoning must have been due mainly to pre-formed toxin.

Consideration is given to the opportunities for the formation of toxin in a spray-drying plant, and reasons are brought forward for believing that it is formed mainly in the balance tank where the warm milk is kept, sometimes for several hours, before passing into the final drying chamber.

The processing of the milk and the precautions for preventing contamination of the finished product are discussed.

Four red cell antigen-antibody systems in the rabbit are described.

Three of these systems, Z, Y and W, appear to be inherited as an allelomorphic series. The fourth is inherited independently.

Some of the serological properties which allow these sera to be recognized are described and attention is drawn to a property of rabbit red cells, manifested by a variation in their susceptibility to agglutination by homologous antisera, which can complicate the separation of a mixture of antibodies in one serum.

1. Rabbit cells show a marked variation in agglutination when reacting with apparently homologous iso-antisera.

2. This phenomenon has been investigated in two ways:

(a) Samples of apparently homologous antisera have been absorbed with (i) strongly agglutinating cells, (ii) poorly agglutinating cells. It was found that strongly agglutinating cells absorbed the antibody completely and rapidly from the serum, whilst poorly agglutinating cells, though they absorbed it completely, did so much more slowly. Also, when a serum which had been absorbed with poorly agglutinating cells until these no longer reacted with it was titrated against strongly agglutinating cells, these were still strongly agglutinated. This showed a source of serious error when investigating new sera by absorption techniques and when using weak antisera for grouping purposes.

(b) Poorly agglutinating cells were injected into rabbits, and the antisera so obtained were examined against strongly agglutinating cells and against the poorly agglutinating cell used as the antigen. The antibody response was poor; two out of eight rabbits developed an antibody, and strongly agglutinating cells reacted more strongly with these antisera than the poorly agglutinating cells which had been used as the antigen.

3. Three hypotheses for this variation in agglutination have been put forward and discussed:

(a) That the variation is due to cross reactions between numbers of closely related antigen-antibody systems. The results of the investigations 2 (a) and 2(b) suggest that this is unlikely.

(b) That the disposition of antigen sites on the surface of the red cell is a factor determining the agglutinability of the cell. It is considered that this might play a subsidiary role in the phenomenon as it is shown in the rabbit.

(c) That rabbit red cell agglutinability is mainly determined by the number of antigen sites on the cell available to the antibody. The experimental results can be explained on this hypothesis, and it is suggested that this may be the main factor accounting for the behaviour of rabbit red cells. It is pointed out that supporting evidence for this is afforded by measurements with radio iodinated antisera.

1. An apparently pure rabbit iso-antibody marked with 131I has been shown to adsorb specifically to a greater extent on some rabbit cells than on others. This accords with previous evidence that the same iso-antibody exhibits a higher titre with the cells which are shown here to absorb more marked antibody than with those which adsorb less.

2. Saturation of two of these red cell types by repeated application of fresh quantities of the 131I iso-antibody until no more is specifically adsorbed, suggests that the number of functional antigenic sites is six or seven times greater on the one than on the other cell.

3. There is no apparent difference in the amount of 131I iso-antibody adsorbed by any one type of rabbit cell in comparative titrations using 3·3 % MgSO4.7H2O medium instead of normal saline.

A micro-drying method is described, which is simple, rapid and reproducible. It has been shown to give results in reasonable agreement with the Karl Fischer method, and with the vapour-pressure method. The results on samples of low moisture content are, however, considerably higher than those by the so-called American standard method. The method has been in routine use for over 3 years.

Soil from a sugar-cane farm in North Queensland was infected with leptospirae. In some instances a culture of Leptospira australis A was added to the soil; in others it was infected by rats, Rattus rattus, known to be excreting leptospirae in their urine.

After periods ranging from 8 to 43 days, the soil was flooded with rain water which was subsequently examined for leptospirae by treating guinea-pigs according to the ‘subcutaneous stream’ technique.

Leptospirae survived in culture-infected soil for 43 days and in urine-infected soil for 15 days prior to the addition of the rain water. They were recovered from the water at intervals ranging up to 24 days after the flooding of the soil.

The infected soil was of pH 6·1–6·2, its moisture content where determined was 34 and 37%, and the prevailing temperature 20–29° C. The reaction of the infected water samples ranged from pH 6·6 to 7·6.

The possible significance of these findings in relation to the epidemiology of leptospirosis in North Queensland is briefly discussed.

Equipment for the sterilization of air by heat with capacities of 140 l./min., and 1700 l./min. respectively is described. An improved method for testing sterility is given.

In an investigation of impetigo among troops, carried out in 1941, nearly half of the strains of Staphylococcus aureus isolated from the lesions had the ability to inhibit the growth of corynebacteria on solid media. A much smaller proportion of strains from other superficial lesions and from nose and throat swabs had this ability, and strains from deep suppurative lesions were uniformly negative.

Three-quarters of Staph. aureus strains isolated from schoolchildren with impetigo in Lancashire in 1953 and early 1954 were of one variety, which could be denned by its susceptibility to typing phages (‘type 71’).

Nearly 90 % of ‘type 71’ staphylococci, and very few others, produced a narrow, sharp zone of inhibition of Corynebacterium diphtheriae mitis on solid media.

A small number of other staphylococci, mainly non-typable or unclassifiable strains, produced a wider, hazy zone of inhibition.

The majority of the impetigo staphylococci were penicillin-resistant, and most of the resistant strains were members of ‘type 71’. However, ‘type 71’ gave rise to only a small proportion of the penicillin-resistant hospital infections occurring in the same district at the same time.

Three-quarters of the Str. pyogenes strains from impetigo lesions belonged to one of two groups of closely related serological types, one of which was rarely encountered in other situations.

Influenza A virus labelled with radiophosphorus was introduced as a primary inoculum into the allantoic sac of fertile eggs. Virus so introduced enters the cells of the chorio-allantoic membrane, and a study has been made of the chemical state of 32P present in the membranes 1½ hr. after inoculation.

It was found that on entry into the host cell the virus particle disintegrates probably as a result of destruction of its phospholipid. Radiophosphorus derived from the virus phospholipid can be recovered from the infected membranes by extraction with physiological saline in the form of compounds of small molecular weight which are not precipitated by protein precipitants and are not sedimentable at a centrifugal force of 100,000 g.

Saline extracts of the infected membranes also contain labelled nucleic acid which appears to be derived from the virus nucleoprotein.

A large part of the nucleoprotein phosphorus of the inoculated labelled virus cannot be recovered from the infected membranes by extraction with physiological saline but can be recovered if the cell nuclear material is dissolved in molar sodium chloride. The 32P in such molar chloride extracts is partly precipitated with the deoxyribonucleoprotein on dilution with water, and is partly present as free nucleic acid.

It is suggested that on entry into the host cell the virus particle is broken down, the phospholipid being destroyed and the nucleoprotein disintegrated with the release of free nucleic acid which enters into a close relation with the cell nuclear material.

The evaporation rates of small particles in aerosols of the following substances have been measured: 4−n−hexyl-1:3-resorcinol, 1, 1, 1-trichloro-2, 2−di (p−chlorphenyl)ethane (‘DDT’), 1, 1, 1−trichloro-2-p−chlorphenyl-2-o−chlorphenyl-ethane (‘op′-DDT’), γ-hexachloro-cyclo-hexane (‘BHC’, ‘Lindane’, ‘Gammexane’), ‘Dieldrin’ and azobenzene.

The slit ultra-microscope method was used; a consideration of the experimental conditions leads to the conclusion that the results are of reliable quantitative significance.

1. The results of an investigation into the clinical, epidemiological and bacteriological features of impetigo contagiosa, with special reference to the type identification of staphylococci and streptococci, are reported and discussed.

2. Of 106 impetigo cases studied, Staphylococcus aureus was isolated alone from 86 lesions (81 %), Streptococcus pyogenes alone from 6 (5·6 %), and a mixed growth of Staph. aureus and haemolytic streptococci in 14 instances (13·2 %).

3. Of the 100 strains of Staph. aureus isolated from impetigo lesions, 63 were identical in phage type (‘type 71’), and a further 17 were closely related (‘weak 71’).

4. Only one representative of ‘type 71’, and 9 of ‘weak 71’, were obtained from 164 strains of Staph. aureus from 200 persons in three control groups.

5. Of 90 strains of Staph. aureus from impetigo lesions, 64 (71 %) were resistant to penicillin. Of these penicillin-resistant strains, 54 (84 %) were of ‘type 71’, or close variants.

6. Strep, pyogenes was probably causative in at least 6 of the 18 patients yielding this organism from lesions; it was presumed to be a secondary invader in the remainder.

7. It is doubtful if nasal carriage is of importance in the epidemiology of impetigo.

8. It is concluded that there is a specific ‘type’ of staphylococcus associated with this form of impetigo.

Sera of 2017 subjects were tested by the slide-agglutination method for the presence of agglutinins to Candida albicans. 638 (31·6%) were positive, and more females than males had positive sera.

The results are reported of quantitative agglutinin estimations in 501 subjects, 121 of whom were known to be infected with C. albicans.

The significance of C. albicans agglutinins is discussed.

Vaccinia virus which has been inactivated by exposure to ultra-violet irradiation under strictly controlled conditions produces an immunity response in rabbits and monkeys. This can be measured by relative insusceptibility to challenge with living virus and by the titration of circulating antibody.

Experiments with small doses of living virus in excess of those that might have been given accidentally indicate that the immune response to the irradiated material was not due to traces of living virus that had escaped detection.

There is a logarithmic relationship between exposure to irradiation and destruction of virus. The exposure necessary to produce complete inactivation can be deduced from a knowledge of this relationship. Excessive exposure destroys the antigenicity of the preparations.

The antigenicity of irradiated virus can be preserved for at least 6 months at 4°C. and at least 2 months at 37°C. by drying from the frozen state.

Circulating antibody is detectable in rabbits for at least 22 weeks following immunization, and a single subsequent reinforcing dose is followed by a secondary immune response.

The possibility that preliminary immunization with irradiated virus may diminish the risk of complications and reduce the severity of the reaction to subsequent Jennerian vaccination with living virus is discussed. This material may provide a basal immunity in those individuals in which vaccination is contraindicated.