The characteristics of Gram-negative organisms and some of the underlying reasons for their adjuvant action with diphtheria toxoid are described.

The adjuvant effect was shown by an earlier production of antitoxin, with a maintained differential advantage over controls, but with the usual decline in titre with passage of time. The adjuvant effect only occurred with a primary stimulus. There was no adsorption between toxoid and vaccine and mixture of the two was not necessary, but the vaccine had to be given simultaneously with or within 24 hr. following injection of the toxoid. There was evidence for believing that these adjuvants decreased the minimal stimulating dose of antigen and caused hyperplasia of antibody-producing cells. No direct link could be found between the characteristic stress symptoms caused by lipopolysaccharides and their ability to enhance antibody formation.

This paper consists of an epidemiological study of 52 cases of Q fever occurring in metropolitan Adelaide in 1957 and also a description of the results of a survey of 516 sera obtained from abattoir workers.

The only case occurring outside the abattoirs was a dairy farmer who probably became infected while visiting the abattoirs. If this were so the incubation period (35 days) of his disease would have been exceptionally long.

The general features of the outbreak, which lasted several months, differed from those on the North American continent in that the latter occurred explosively within a few days with very high attack rates. The situation in the Adelaide abattoirs is similar to that in Brisbane, where the disease appears to be endemic. However, unlike in Adelaide, cases are commonly recognized outside the abattoirs in Brisbane.

In the abattoirs the disease affected mainly inspectors, those working on killing beef, and those working on offal. Mutton workers were not so severely affected. However, all these groups had similar incidences of low titre antibodies suggesting that in the past Q fever spread equally in all killing departments. In departments not directly associated with slaughtering the incidence both of cases in 1957 and low titre antibodies was relatively small.

It was suggested that the epidemiological features of Q fever in Adelaide could be explained by the irregular appearance of animals from infected herds situated perhaps in Queensland—a known endemic area. Perhaps the appearance of such animals in the Adelaide abattoirs might be governed by meteorological conditions such that they were prevented from going to the ordinarily most convenient slaughterhouse.

Experiments carried out by the British Egg Marketing Board in order to establish a heat treatment which would effectively pasteurize liquid whole egg are described.

The results of large scale bakery trials and subsequent trade demands indicate that the recommended pasteurization treatment gives a product of a satisfactory baking performance.

It is recommended that for the adequate pasteurization of whole-egg products, a temperature of 64·4°C. (148° F.) for the minimum holding time of 2·5 min. should be used.

No evidence was found to support the view that coliphages as such play an important role in reducing the number of E. coli in sewage water when it is treated in oxidation ponds. Coliphages seem to have greater powers of survival than E. coli in oxidation ponds.

Test baiting has shown that rats underground are distributed in a series of discrete colonies, each one in close association with a group of men. Interplay between colonies is rare in large mines although evident in small ones. In the absence of stables the rats must depend almost entirely on miners’ food scraps.

These observations were made during work carried out under a research grant from Safety in Mines Research Establishment, Ministry of Power, and I am indebted to the Ministry for permission to publish the results. I should like also to express my gratitude to Dr E. T. B. Francis who supervised the work, Mr. C. S. W. Grice of the Ministry of Power and Miss B. B. Jones of the Ministry of Agriculture, Fisheries and Food for their help in various aspects of the work.

Sera of 132 selected patients belonging to stages II, III or IV of clinical trachoma have been tested by CF-test against the ether-soluble, group-specific Bedsonia antigen, as well as by CF-inhibition test against an indicator system of the same group-reactive specificity.

On the basis of the serological results obtained, the following conclusions have been advanced:

Trachoma patients do not develop group-specific CF-inhibiting antibodies in their sera.

The group-reactive (anti-Bedsonia) CF-titres found in sera of trachoma patients represent residual titres developed in response to past infections with agents other than trachoma. There is no satisfactory explanation for the fact that in trachoma patients neither CF, nor CF-inhibiting antibodies develop against the group-reactive Bedsonia antigen, which is known to be produced also by the virus of trachoma.

Statistical analyses revealed that, in the group of stage IV trachomas, the mean values of the anti-Bedsonia CF-titres were significantly higher than those found in the groups of stage II or III, as well as that the factors responsible for that difference must be other than the duration of the trachoma.

A hypothesis was advanced to explain the appearance of the highest group specific mean-titre revealed by the group of stage IV cases.

The activity of the enzyme α-amylase of whole egg is known to be sensitive to pasteurizing temperatures and the possibility that this property could be used as a control test for the adequacy of pasteurization has been examined.

The occurrence of the enzyme, the physico-chemical characteristics of its heat inactivity, the consistency of its behaviour in large numbers of eggs and the influence on its of packing station procedures has been studied.

By sampling eggs from many sources for 11 months it was concluded that the activity of the enzyme was consistent, the inactivation by heat was a first-order reaction, and freezing, thawing, homogenization, spray-drying and in the laboratory freeze-drying did not affect its inactivation. But there was some interference from added citrate and sucrose.

The growth curves of young mice experimentally infected with L. australis A, L. australis B, L. grippotyphosa or L. icterohaemorrhagiae fell into two types, a ‘lethal’ pattern of continued weight loss until death, or a ‘carrier’ pattern of retardation of weight gain. The ‘carrier’ pattern could be changed to the ‘lethal’ by increasing the size of the infecting dose of a given serotype, or vice versa. Infection with L. icterohaemorrhagiae in newborn mice was fatal, while adults became carriers; susceptibility to infection with L. australis B decreased with increasing age.

The numbers of infecting leptospirae and the age of the mouse determined the outcome of infection with a given serotype in a standard test animal. The basis of species susceptibility is unknown, but it is suggested that variation in the ability to produce lesions is the basis of the differences in virulence between serotypes. The ‘host of election’ in leptospirosis is regarded as the result of a quantitative rather than qualitative adaptation of host and parasite to one another.

The conditions of heating necessary to destroy salmonellae in liquid whole egg have been compared with those necessary to destroy the activity of the α-amylase of whole egg. All conditions of pasteurizing from the mildest at 61·1° C. (142° F.) for 1 min. to the most severe at 65·5° C. (150° F.) for 5 min. eliminated Salm. typhimurium. The heat-resistant strain of Salm. senftenberg N.C.T.C. 9959 (775 W) was not recovered after heating at 64·4° C. (148° F.) for 2½ min. and at the lower temperatures when the heating period was 3 min. or more. The activity of α-amylase was also destroyed by heating at 64·4° C. (148° F.) for 2½ min. but not at lower temperatures.

Because the baking properties of egg are not impaired by heating at 64·4° C. (148° F.) for 2½ min. it is proposed that the inactivation of the α-amylase of whole egg can be used as a test for controlling the pasteurization process, and a routine test has been developed which can be completed within 1 hr.

The result of penicillin prophylaxis of experimental inhalation anthrax in the Rhesus monkey has been shown to be dependent upon the time of its initiation. If begun too early, it is unsuccessful. It may not be too long delayed, or the infection will have passed the point of no return. A brief, critical time period exists, during which successful prophylaxis may be initiated. This favourable outcome is attributed to the elaboration in vivo of sufficient antigen or antigens to stimulate an adequate immune response, prior to the initiation of antibiosis.

Investigations carried out to ascertain the ability of various strains of Bordetella pertussis and B. parapertussis to produce agglutinins have shown that the agglutinin response is considerably greater with B. parapertussis.

Children inoculated with a combined vaccine in which the parapertussis element contained B. parapertussis in only one-twelfth of the concentration of B. pertussis in the pertussis element showed agglutinins in their sera in titres well above 1:300 for both organisms. There were no cross-reactions and the serological responses were specific throughout. The vaccine used was the standard diphtheria-tetanus-pertussis (DTP) prophylactic to which had been added a vaccine prepared from recently isolated strains of B. parapertussis.

Agglutinin titres of both whooping cough components with the combined vaccine were somewhat lower in mice than was the case when monovalent vaccines were used, but they were considered to be satisfactory.

It is suggested that the agglutination production test in mice could be used for the assessment of protective power of B. parapertussis vaccines against infection.

I wish to thank Dr Ikić, director of the Institute of Immunology, Zagreb, who enabled me to perform all these examinations, further to Dr B. Mravunac and Dr Z. Radanov for having carried out vaccination in children and for the clinical examination of post vaccination reactions.

The growth of L. australis B in the kidneys of young mice which become carriers was followed after experimental intraperitoneal infection. There was a primary growth corresponding to generalized acute infection and terminated at the time of appearance of antibody. A secondary growth bf leptospirae followed in the kidneys alone about 7–10 days after infection, coinciding with the onset of leptospiruria and recovery from infection. Subsequently mice carried about 106–107 leptospirae in their kidneys permanently.

The leptospirae in the urine or in the kidneys of carriers were resistant to the action of antibody in the serum or urine of the host animal, or in rabbit antisera prepared against mouse-renal leptospirae or against cultured leptospirae of the infecting strain. No antigenic differences were detected between renal and cultured leptospirae. An analogous situation is the growth in vitro of leptospirae in homologous antiserum. The mechanism permitting growth of leptospirae in homologous antiserum in vivo or in vitro is unknown.

The carrier condition results from the ability of virulent leptospirae to (i) grow in the host and produce lesions in the primary, acute generalized infection, (ii) grow in renal tubules in the presence of antibody.

Of the ordinary infections sustained by children during the first 5 years of life 56% were common colds, 16·5% other infections of the respiratory tract, 16% gastro-intestinal catarrhs, 6% infections of the skin and mucous membranes and 5·5% infectious diseases in a strict sense.

Common colds were most frequent in the second year, namely, an average of 4·3 common colds per child per year. As the child grew older the number of colds decreased. Adults showed an average of two common colds per year.

Of the ‘other infections of the respiratory tract’, 42% were undifferentiated respiratory tract infections, 23% febrile affections without definite localization, 17% otitis, 11% pharyngitis and 7% influenza. The frequency of these ‘other infections of the respiratory tract’ rose from 0·3 in the first to 1·8 in the fifth year of life. After the fifth year the frequency diminished to one infection every 2 years in adults.

The frequency of gastro-intestinal catarrhs in the first year of life, namely, 0·6 per child per year, was doubled in the second year, and then remained constant for a few years. After the fifth year a decrease was observed in this figure too.

Fifty-four per cent of the 116 index children sustained at least one suppurative skin affection during the first 5 years of their lives, 28% had more than one. Most pyodermias occurred in the first few months of life, a second maximum being observed in schoolchildren, 21% of the index children had stomatitis in the first 5 years, 42% conjunctivitis.

By their fifth birthday, 49% of the 116 children had had measles, 46% chicken pox, 26% rubella, 24% exanthema subitum, 17% mumps, 3% whooping cough, while 2 of the 116 children had had scarlatina, 1 child hepatitis, 1 poliomyelitis and 1 bacterial meningitis.

No difference in morbidity was found between boys and girls in respect of respiratory tract infections. The boys had skin infections distinctly more often than the girls, and infections of the mucous membranes and of the gastro-intestinal tract were also slightly more frequent in boys. Apart from infections of the skin and mucous membranes, which were more often observed in mainly bottle-fed children, ordinary infections were equally frequent in this latter category and in children mainly breast-fed.

The index child with older brothers and sisters contracted the ordinary infectious diseases younger than the index child who was the eldest child in the family. On account of the presence of older children in the family, a child was ill not more often, but earlier. The infections of the respiratory tract showed a distinct preference for the winter months, and the frequency of gastrointestinal infections was also slightly higher in that season.

Febrile affections without definite localization, as well as infections of the oral mucosa, occurred especially during the summer months.

Going to the kindergarten did not lead to an increase of the frequency of common colds and gastro-intestinal catarrhs, but the number of infectious diseases in a strict sense became higher. The ‘other infections of the respiratory tract’ became more frequent under the influence of school only in those index children who were the eldest in the family. The index children from families with a low level of hygiene experienced more infections of the skin and mucous membranes than those from families with a high hygienic level.

No difference between these two groups was demonstrable in regard to the other ordinary infections.

There was a parallelism between the frequency of common colds and of gasto-intestinal catarrhs but not with the other minor infections.

Fluorescent antibody techniques were used for detection of plague antigens in infected mouse carcasses stored at 4°–5° C., 20°–25° C. (room temperature) and 370° C. for periods as long as 340 days in certain cases. Tissues of two guinea-pigs infected with Pasteurella pestis were examined after 7 years storage at room temperature. The efficacy of the fluorescent antibody test was compared with blood agar plate culture and animal inoculation during periods in which viable plague bacilli were presumed to be present, and compared with Larson's modified Ascoli test for the presence of soluble plague antigens during periods in which plague bacteria were presumed to be non-viable.

Fluorescent antibody tests were superior to animal inoculation or cultural methods in detection of P. pestis antigens in mouse carcasses stored for 4 days or longer at 37° C., for 8 days or longer at 20°–25° C. (room temperature), and for 34 days or longer at 4°–5° C. Upon examination of specimens presumed to lack viable plague organisms the fluorescent antibody test and precipitin tests were approximately equal in efficiency for detection of plague antigens in carcasses stored for 16–82 days at 37° C. and for 16–82 days at 20°–25° C. Ten of 21 mice stored for longer periods (140 and 340 days) at 4°–5° C. were negative by precipitin tests, whereas 19 of the same 21 rodents were positive by fluorescent antibody tests. In addition, after 7 years storage at room temperature tissues of two plague-infected guinea-pigs were negative by Larson's modified Ascoli test but positive by the fluorescent antibody test.

In experiments on survival of microbial aerosols, viability should be measured as early as possible in the life of the cloud, but this must not be used as the datum to which subsequent viabilities are related; all viabilities must be related to that of the material from which the cloud was generated. Mathematical models may be used as a convenience in expressing results, but observed viabilities must also be quoted.

I am indebted to the many colleagues whose work over the years has consolidated this approach, and particularly to Mr G. J. Harper whose experiments and thinking form the backbone of my discussion.

1. Ten strains of Sh. sonnei were placed upon metal, wood, cotton, paper, and glass and held at −20°, 4°, 15°, 37° and 45° C. Survival of the cells was most extensive when placed at −20° C. and practically none of the strains survived when held at 45° C.

2. Slight variations in the survival of different strains was observed when the cells were placed upon glass and cotton. Strain variation was greater when survival time was measured by placing Sh. sonnei on wood, paper, and metal.

A technique involving the suppression of normal intestinal flora with antibiotics, and the introduction of streptomycin-resistant coliforms was used for the study of infections in mice.

It was shown that Escherichia coli, both the enteropathogenic and normal faecal strains, tend to colonize the upper intestinal tract as well as the lower region. An oral dose of ten or less cells could produce a chronic infection. Infections were asymptomatic even with an initial dose of 109 bacteria. There was no indication of growth advantages for enteropathogenic coliforms in competition with normal.

1. The nasal carriage of Staph. aureus and its relation to disease was studied in new recruits, boy apprentices and trained men of the Royal Air Force.

2. The proportions of Staph. aureus that were penicillin-resistant ranged from 15% in new recruits to 29% in trained men. In a school for apprentices the rate in new arrivals was 18%, and 23% for boys after the initial training. We were unable to find when these changes occurred.

3. 31% of strains isolated from septic lesions were penicillin-resistant and the rate was similar in all types of unit. Resistant strains were not apparently more virulent than sensitive strains.

4. About 1% of all strains isolated were resistant to tetracycline and streptomycin and much smaller proportions to chloramphenicol and erythromycin.

5. The phage-group distribution was similar for nasal and lesion strains, but nearly half the penicillin-resistant lesion strains belonged to Group I, and types 52A and 3C/55/71 were much commoner in lesions than in the nose.

6. Penicillin-resistant strains were more readily acquired and more rapidly lost than the sensitive strains.

7. Nasal carriers suffered from septic lesions more frequently than non-carriers, and those with a lesion tended to suffer further lesions. There was no evidence of cross-infection among bedroom contacts.

8. The proportion of penicillin-resistant strains rose from 30 to 40% between admission to and discharge from service hospitals. Resistant strains were not carried for long after discharge.

9. Penicillin treatment resulted in a fall in the total carrier rate and a rise in the resistance rate. Phage type analysis showed that this was mainly due to elimination of sensitive strains and recolonization with resistant strains.

We are greatly indebted to Miss Susan Green for the large amount of work that she did in the laboratory. We should like to thank also many Royal Air Force medical officers for their assistance, in particular Wing Commander E. S. Odbert, Wing Commander M. White, Squadron Leader M. Shearer and Flight Lieutenant A. J. Zuckerman; and the Director-General of the Royal Air Force Medical Services for permission to publish the results.

Cowpox soluble antigen is shown by gel-diffusion studies to contain at least nine precipitable substances whose presence is induced by virus infection. One of these substances, pattern component d, is not produced in white cowpox infections, and its production in vaccinia infection can be inferred only from the presence of small amounts of anti-d in anti-vaccinia sera.

Comparison of cowpox with vaccinia has led to the recognition of a further line pattern component f which is readily demonstrated as a soluble precipitable substance in simple buffer extracts of vaccinia-infected tissue, but is demonstrated in extracts of cowpox-infected tissue only with difficulty; anti-f antibody is readily detected in antisera prepared against cowpox, white cowpox, and vaccinia.

Among 309 cultures of Salmonella typhimurium, phage-type 27, fifteen, isolated from eight patients, were found to be resistant to the three drugs, streptomycin, tetracycline and sulphathiazole. This triple resistance could be transferred by growth in mixed broth culture to a strain of Skigella sonnei and back again to sensitive cultures of S. typhimurium. In whole cultures the resistance was stable, but spontaneous loss could be demonstrated in a small proportion of the organisms in such cultures. No elimination of resistance was demonstrated after treatment with acriflavine. Resemblances to the multiple drug resistance in enteric bacteria reported from Japan are noted.

The author is most grateful to Dr E. S. Anderson, Director of the Enteric Reference Laboratory, Colindale, N.W. 9, for phage-typing the cultures of Salmonella typhimurium, and to Dr K. Patricia Carpenter, Director of the Dysentery Reference Laboratory, for supplying cultures of Sh. sonnei which were essential for the experimental work.