Semliki Forest virus was passaged 10 times in series in calf kindly cells, starting with virus passaged in the mouse brain (MB virus). A variant was obtained (termed CK virus). The two viruses were antigenically indistinguishable. When grown on L cells, CK virus formed smaller plaques than MB virus. In parallel growth curve studies in calf kidney cells, a small inoculum of CK virus grew more rapidly and to a higher final titre than a comparable inoculum of MB virus, and usually stimulated production of less interferon. Pre-treatment of cells with calf interferon reduced the growth of both viruses, but especially that of MB virus. The results are considered in relation to the phenomenon of virus adaptation. It is suggested that such differences between the two variants in their relative sensitivity to and production of interferon could have played a part in the emergence of CK virus as the predominant type during serial passages in calf cells.

I wish to thank Mr H. Moores and Mr R. Sims for skilful technical assistance.

The residential home was investigated to study the endemic virus population. During this study, oral poliovirus vaccine was given to the children and the effect of vaccination on endemic enteroviruses and adenoviruses was investigated. In the light of these findings, the problem of virus interference is discussed. The health of the children is related to their virus infections.

We are indebted to Prof. S. D. M. Court and Prof. C. A. Green for the active interest they have taken in this investigation; to Miss J. McQuillin, B.Sc., F.I.M.L.T., for her technical assistance; also to the matron of the home and her staff for their co-operation in supplying the specimens, and to Mr L. J. Whitlock of the Royal Victoria Infirmary and his staff for arranging their transport to the laboratory.

A survey of serum samples from all age groups in the population has shown a rapid acquisition of antibody between the ages of 1 and 6 years which reaches a plateau in concentration and does not disappear later.

The concentration of antibody in cord serum may be four or more times greater than that in the mother's serum.

Presence or absence of a record of past infection by measles is not necessarily reflected by the titre of antibody in the serum.

Low antibody titres in very young infants may be due to an imperfectly developed antibody producing mechanism.

The author gratefully acknowledges the assistance of all those who made this survey possible. In particular, she is indebted to Dr G. I. Watson of the College of General Practitioners and his colleagues (see list) for their help in the collection of so many of the serum samples, and to Mr D. A. Bamgboye for his excellent technical assistance.

Leptospirosis is a zoonosis that causes appreciable ill health and economic loss in North Queensland. Fourteen serotypes of Leptospira were known to infect man in the area, and information on their local distribution and seasonal and occupational incidence had been obtained. The next step in the investigation was to determine the reservoir hosts and estimate their significance.

Wild animals examined comprised 5 monotremes, 643 marsupials, 2355 rodents, 67 bats, 30 birds, 28 reptiles, and 21 toads. Evidence of leptospiral infection was obtained from 223 marsupials, 309 rodents, and 6 fruit-bats. Analysis indicated that the principal maintaining hosts were: Peremeles nasuta—of L. kremastos (and possibly L. mini) in canefields and rain forest.

Isoodon macrourus—of L. broomi, L. mini, and L. kremastos in canefields.

Rattus rattus, R. norvegicus (focal), and Mus musculus (focal)—of L. zanoni in town and canefields.

Rattus sordidus conatus—of L. australis in canefields.

Rattus assimilis—of foci of L. australis, a variant of L. pomona, and probably of L. hyos in rain forests.

Random infections were also encountered, but the maintaining hosts of the other serotypes known to infect man in the area (icterohaemorrhagiae, canicola, bindjei, robinsoni, bratislava, grippotyphosa, medanensis, celledoni) were not determined.

Domestic animals examined included 137 cattle, 54 pigs, 7 sheep, 34 dogs, 31 cats, and a dairy herd in which there was an epizootic of pomona leptospirosis. Again, there was a wide scatter of infection, but, apart from the long-known association of L. pomona and L. hyos with cattle and pigs, there was no evidence of maintaining hosts in this series.

As indicated in the Introduction, the work reported here was part of a planned investigation into the epidemiology of leptospirosis. Some of the early material was collected by Dr M. J. Mackerras, Dr R. L. Doherty, Mrs D. G. Delamoir, and Miss C. J. Ross, who had previously been stationed at the Institute's Field Station, and we are indebted to Mr D. W. Lavers, Mr S. G. Knott, and Mr R. E. Dunham, of the Queensland Department of Agriculture and Stock, for a number of sera from domestic animals. Many of the mammals were identified by Dr W. A. McDougall, of the Queensland Department of Agriculture and Stock, Mr E. le G. Troughton, then of the Australian Museum, Sydney, Mr B. J. Marlow, then of the C.S.I.R.O. Wildlife Section, Canberra, and by Dr J. L. Harrison, Dr M. J. Mackerras, and Mr R. Domrow of the Institute. We are indebted also to Mrs M. Macgregor, Librarian of the Institute, for considerable help with the literature.

A previously unidentified type of Mycoplasma found as a contaminant in tissue cultures and in a culture of Eaton agent, is identical with a newly recognized human oral type.

I am indebted to Drs Herdersheê and Chanock for sending me their cultures and relevant information.

Investigations in the Mossman districts of North Queensland showed the maintaining hosts of leptospiral serotype medanensis to be Perameles nasuta and Isoodon macrourus in canefields, secondary woodland and rain forest. Rattus sordidus conatus is the maintaining host of grippotyphosa in canefields. The host range of six serotypes was extended by the cultural studies.

We would like to express our thanks to Dr G. Alberts, superintendent of Mossman District Hospital, for his co-operation, and also to Miss H. MacDonald and Mr A. Wood for technical assistance.

1. Following an epizootic of louping ill on certain farms in south-west Ayrshire in 1960, a long-term study of several farms was initiated.

2. The flocks on two hirsels of one farm were studied during spring and early summer of 1961. Although only one lamb death was confirmed as due to louping ill, the infection rates in sentinel hoggs on the two hirsels were 50–60. and 11% respectively. The difference between the hirsels is probably attributable to the difference in the amount of tick habitat on them.

3. The ewes were bled in March and June and their lambs in June. Haemagglutinin inhibition (HI) and neutralization tests revealed that the HI antibody is much shorter lasting than neutralizing antibody. Many ewes, therefore, had neutralizing but not HI antibody. Otherwise agreement between the tests was good. In March almost all the ewes aged 3 years or more had antibody. Of the gimmers (2-year-olds) about two-thirds on one hirsel and one-third on the other had antibody in March: by June almost all the former and about half of the latter had antibody.

4. About two-thirds of the lambs had the same antibody status as their mothers in June and almost all the rest had less antibody than their mothers. Serological evidence suggestive of louping ill without recognizable clinical disease was found in six lambs and a further lamb recovered from clinical disease.

5. Revaccination of two-thirds of the flock failed to cause any detectable change in antibody status.

6. The epidemiology and pathogenesis are discussed in relation to immunity and infection rates, and to the design of control measures.

We are greatly indebted to the late Mr James Murdoch at Dalmellington, Mr John Murdoch at Dalcairnie Farm, and Mr David Murdoch at Knockgray Farm for permission to work on their farms and for all the help they gave us during the study.

Complement-fixation tests with psittacosis-trachoma group antigens, if set up with complement prepared from guinea-pigs cross-infected with any of the Bedsonia agents, may give completely false positive results. The use of C.F. positive or C.F. inhibition positive samples of guinea-pig sera as a source of complement can induce also a significant increase or decrease, respectively, of the actual C.F. titres in Bedsonia-positive serum samples tested. Observations made both in routine serology and in experimental studies show the necessity of testing carefully, for possible presence of Bedsonia titres, individual sera of guinea-pigs intended for use as source of complement in C.F. tests performed with Bedsonia group antigens.

I have pleasure in thanking Dr F. B. Gordon and Dr E. Weiss for the valuable suggestions made and HM3 C.O. Wiese for the technical assistance.

1. Non-specific stimulation of mice by a detergent lacking in vitro antibacterial activity, Triton WR 1339, produces a steady state in the course of experimental tuberculosis at about the same level as specific immunization, and does so independently of delayed allergy.

2. This effect is achieved in a much shorter time than is required by the normal immunological processes and the relative duration of enhanced resistance in each case is yet to be worked out.

3. Triton fails to enhance an existing, specifically acquired immunity.

4. There is no evidence so far that the mechanism involved is the same in both instances. If it were found to be the same, then the present concept of a specific cellular immunity would need to be revised.

Group-reactive ether soluble psittacosis and boiled mouse pneumonitis antigens were tested in parallel, with 85 serum specimens. The results indicate that the group-specific C.F. antigens of these organisms are indistinguishable when tested against sera of trachoma patients, monkeys infected with trachoma or against sera of other individuals.

Sera of rabbits immunized with viable trachoma-inclusion conjunctivitis (TRIC) organisms, grown in tissue culture, were absorbed with boiled elementary body suspension of mouse pneumonitis agent, which removed the group reactive antibodies, and resulted in a species-specific anti-TRIC serum.

The absorbed and unabsorbed TRIC sera were titrated against purified E.B. suspensions, which were prepared both from yolk and from tissue culture grown organisms, of homologous TRIC strains and from other heterologous Bedsonia organisms.

Results of absorption experiments indicate that group reactive antigens prepared from mouse pneumonitis and psittacosis are indistinguishable by C.F. test from the group-specific component of the TRIC antigens. The species-specific antigen of the TRIC agents was well distinguished from the species-specific antigen of the psittacosis agent. However, the C.F. test did not distinguish the strains isolated from trachoma from those isolated from cases of inclusion conjunctivitis.

The stabilizing effect of sucrose and albumin upon the species-specific C.F. antigen of purified elementary bodies of TRIC organisms was found to be pronounced.

Our attempts to produce a species-specific antigen preparation, free from group component, failed.

We have pleasure in thanking Dr F. B. Gordon for suggestions; Dr B. V. Birtašević, Mr H. R. Dressler, Dr E. S. Murray and Dr A. J. Vargosko for procuring sera of patients or organisms grown in tissue culture; Dr T. A. Strike for the help with statistical computations; HMC P. R. Hill, HM3 C.O. Wiese and Mr B. L. Ward for invaluable technical assistance.

A chemically defined fluid medium—improved formate lactose glutamate—is described of which the cost is less than a quarter that of standard MacConkey broth and which is at least equally suitable for routine bacteriological examination of water. It has actual advantages in that the medium after fermentation is clearer and that, therefore, acid and gas production is more easily seen; moreover more isolations of both coliform bacteria and of Esch. coli are obtained with fewer false positive reactions. Trials with a solid version of the medium suggest that the relative freedom from false positive reactions arises from the failure of the medium to grow Cl. welchii—one of the commonest causes—and enterococci, another suspected participant. In fact, without any inhibitory agent the medium appears to be virtually specific for the coliform group and particularly favours Esch. coli. It remains to be seen whether certain aerobic spore-bearers found from time to time in surface waters may, to some slight extent, interfere with the almost complete specificity so far discovered.

The medium is recommended in place of MacConkey broth and other peptonecontaining media, not only for the prospect of better results, in that suppression of the coliform group does not occur, but also for cheapness and for freedom from the inevitable variability associated with media incorporating peptone and, particularly, bile salt. It is hoped that this medium will shortly become available commercially in dehydrated form at a price still considerably less than that required to make up MacConkey broth from its constituents.

Some labour-saving curtailments in the routine of water examination are also suggested.

It is hoped not only that the fluid medium will supplant MacConkey broth for the dilution method of water analysis but that the solid medium, without material alteration, will also prove suitable for water examination by membrane filtration.

I am deeply grateful to my laboratory staff, particularly Mr J. H. Evans, F.I.M.L.T., and Mr G. H. Lowe, F.I.M.L.T., for undertaking so much of the work when routine work was particularly heavy, and for many valuable suggestions. My thanks in addition are due to Mrs Peggy Johnson and Mrs Marilyn Childs, who made up the medium, and also to the directors of the participating P.H.L.S. laboratories not only for having the work carried out but for helpful comments.

Variation in agglutinating and protective antigens was studied in a strain of Trypanosoma brucei growing in mice protected with anti-trypanosomal rabbit serum. It was concluded that the agglutinating and protective antigens were the same, and that variation in the antigenic structure of trypanosome populations exposed to antiserum was due to mutation and selection rather than to adaptation. The mutation rate per organism per division cycle required to account for the experimental findings on the mutational hypothesis was found to have a mean value of 10−5.17.

Polyvinyl-pyrrolidone-iodine complex (PVP-I) was shown to have a rapid disinfectant activity in vitro against vegetative bacteria and fungi and against vegetative Trichomonas. The presence of organic matter had a slight delaying effect on the killing time. Bacterial spores survived in PVP-I for 17 hr. and fungal spores for 1½ hr. Used as an agent for pre-operative preparation of the skin, PVP-I was more efficient than others tested, rendering the skin surface sterile even when heavily contaminated, and keeping it so for 1 hr. None of the staining characteristics of iodine were noted since PVP-I was easily removed by water. Two individuals, known to be iodine sensitive, developed mild iodism after application of PVP-I.

The authors are indebted to the staff of the hospital for their co-operation; and to Berk Pharmaceuticals Limited for supplies of PVP-I, manufactured by them as Betadine (Povidone-iodine B.P.).

A complement fixation test with rabbit antisera was used to differentiate 82 cultures of Mycoplasma from man, mammalian cell cultures, laboratory rats and mice, cattle, goats, poultry, embryonated eggs and sewage.

Seventeen serotypes were distinguished, 5 from man, 1 from mammalian cell cultures, 4 from rats and mice, 4 from cattle and goats, 2 from poultry and one saprophytic. Most of these corresponded to recognized species of Mycoplasma, but 1 of human origin (represented by 1 strain, Navel), and 1 from tissue cultures (5 strains), may represent new species. R38, one of the serotypes from rats, could be distinguished from the species M. arthritidis, but is probably an antigenic variant rather than a distinct species. Two species hitherto recognized as distinct, M. arthritidis and M. hominis type 2, could not be distinguished and appear to constitute a single species. These findings illustrate the necessity, from the viewpoint of taxonomy, of comparing mycoplasma strains by serological methods.

The serotypes of human and animal origin were largely host-specific. Exceptions were the inclusion of M. arthritidis from rats and M. hominis type 2 from man in a single serotype, the finding of a bovine organism among the strains isolated from goats and of a saprophytic strain in a rat.

In relation to the aetiology of disease in man and animals, the isolation of an endogenous Mycoplasma from embryonated eggs used to passage infective material illustrates the importance of identifying these organisms serologically. The demonstration of mixed mycoplasma infections in lesions in two rats shows the necessity of adequately purifying all cultures of Mycoplasma before examination.

I would like to thank those workers mentioned in Table 1 who kindly provided the cultures which they isolated. In addition I wish to thank the following who sent cultures: Prof. A. C. Ruys and Dr D. Herderscheê (Amsterdam) for G2, Prof. H. E. Morton (Philadelphia) for Campo and 07, Dr D. G. ff. Edward (Beckenham) for Campo (PG27), M. bovigenitalium (PG11), M. iners, and M. gallinarum, Dr R. G. Wittler for H606 and Miss A. G. Newnham for A36, TU, PSU4 and TC727.

My thanks are also due to Dr L. H. Collier of this Institute, Dr G. W. Csonka (London), Prof. A. E. Macdonald (Aberdeen), Dr J. Payne (Edmonton, Alberta), Mr A. A. Tuffrey (Carshalton) and Dr D. Weisinger (Basle) who provided material from which PPLO were isolated. I gratefully acknowledge all the information so generously supplied by these workers about the strains or material provided.

I am indebted to Miss A. G. Newnham for carrying out an agglutination test on the avian strains.

Part of this work was carried out by the author under the author aegis of the Medical Research Council Working Party on Non-Specific Urethritis with the aid of a grant from the U.S. Public Health Service.

An attempt has been made to study quantitatively the mechanisms by which infectious materials may enter the body by the upper respiratory tract and be shed during a cold.

The rapid clearance of tracers, spores of B. mycoides and bacteriophage type T3, has been measured after adding them in small drops to the nose, conjunctiva and mouth.

Tracers placed in the nose pass rapidly down the throat, but are found in only small amounts in the saliva. They are dispersed by blowing the nose and, more efficiently, by sneezing. Nearly all are shed as coarse droplets. About 0·1% are shed in droplets small enough to remain airborne and just over half of these are in the size range likely to be trapped in the upper respiratory tract. The droplets are apparently formed mainly in the nose. The larger amounts of droplets formed in the mouth carried relatively few infectious particles.

Testing by experiments in a model system it was concluded that most of the coarse droplets produced by a sneeze or by an experimental spray fall rapidly to the floor. A few of the larger droplets were trapped on a moistened microscope slide intended to mimic the possible trapping of droplets on the conjunctive. The spores in these represented only a small proportion of those found in droplets which remained airborne and were collected by an air sampler.

We wish to thank Miss P. D. Ball for technical assistance and Dr J. E. Lovelock for helpful discussion in the early stages of this work. We are also grateful to Sir Victor Negus and Dr B. Wyke for discussing the physiology of the nose with us, and to Mr K. R. May for his advice on methods of air sampling. The air samplers were loaned by the Microbiological Research Establishment, Porton, and the photographs taken by the Chemical Defence Experimental Establishment, Porton.

A total of twenty-five grade cattle were infected experimentally with a strain of rinderpest virus of moderately high virulence (RGK/1). Three methods of introduction of the virus were employed, i.e. subcutaneous or intranasal inoculation (14 animals) and housing in contact with reacting cattle (11 animals).

A quantitative study of the viraemia and of virus excretion by the nasal, urinary and faecal routes, was made by the inoculation of primary calf kidney cultures. All virological data were related to the onset of pyrexia, the incubation period in inoculated animals being 3–5 days, while in those infected by contact it was 8–11 days. Viraemia preceded the first rise of temperature by as much as 2 days in inoculated animals and 1 day in the contact cases. All animals had viraemia by the 4th day of the disease, but thereafter the percentage of positives declined rapidly, reaching nil by the 9th day.

The case mortality rate was 48 % with the majority of animals dying on the 7th to 10th days after reaction.

Virus was detected in the nasal secretions of some animals on the 2nd day preceding pyrexia. The proportion of nasal excretors rose slowly to reach a maximum of 87·5 % on the 4th day and no positives were detected after the 9th day of fever. The titre of virus in nasal discharges reached high levels, often probably in the region of 105·0 to 106·0 TCD 50/ml.

Urinary excretion of virus began on the 1st day of fever in about 25 % of animals; reaching a maximum of 62·5 % on the 7th day. No virus was recovered from the urine after the 8th day of the disease, the rapid decline in the excretor rate being only partially attributable to the death of severe cases. Urinary titres were relatively low; they seldom exceeded 102·0 TCD 50/ml.

Virus was first recovered from the faeces on the 3rd day of pyrexia. Excretion by this route was not constantly associated with the development of diarrhoea, but the rapid decline which occurred in the excretor rate on the 8th and 9th days was undoubtedly attributable to the death of diarrhoeic individuals which took place at that time. The majority of faecal titres were in the approximate range of 103·0 to 104·0 TCD 50/g. but occasional samples attained ca. 106·0 TCD 50/g.

It was calculated, from the clinical and virological data that cattle can excrete virus, at least by the nasal route, as much as 6 days before the appearance of pathognomonic clinical signs, i.e. oral necrosis and erosion.

Our findings for rinderpest were compared with those of other investigators of this disease and also with the available information on canine distemper and human measles.

We are very grateful for their able technical assistance to Messrs L. W. Rowe, C. S. Rampton and R. F. Staple. Particular thanks are due to Mr C. S. Rampton for his preparation of all the figures. We have received considerable and indispensable help from our junior laboratory staff, especially Mr Francis Ngugi Gachuhi and Mr Joash Adero.

This paper is published by permission of Mr H. R. Binns, C.M.G., O.B.E., the Director of the East African Veterinary Research Organization.

A variety of surfaces was tested for self-disinfecting action against Staph. aureus and Esch. coli at a humidity of 42%. Surfaces which had been treated with disinfectants sometimes reduced the survival when the organisms were applied subsequently in drops of broth, but the reduction was very small unless the surface was able to absorb appreciable amounts of disinfectant and the drop of inoculum spread. When the inoculum was applied dried in cotton dust, only surfaces which evolved formaldehyde showed any activity against the bacteria. These surfaces also reduced the survival of bacteria in liquid inocula.

We would like to record our thanks to Dr O. M. Lidwell for much helpful advice.

1. Simultaneous active and passive immunization of guinea-pigs using tetanus toxoid adsorbed on to aluminium hydroxide produced a higher antitoxin response than simultaneous immunization using plain toxoid. The response was also better than that produced by plain toxoid alone.

2. A 24 hr. interval between the injection of plain toxoid and the subsequent injection of antitoxin gave no better results than when toxoid and antitoxin were given at the same time.

3. The response to simultaneous immunization, using adsorbed toxoid, of guinea-pigs sensitized to horse serum, was superior in the first 6 weeks to that of guinea-pigs which had not been sensitized.

4. The suggestion that simultaneous active and passive immunization of man should be performed with adsorbed toxoid rather than plain toxoid is supported by these results.

Early in 1963 neomycin-resistant Staph. aureus appeared in the burns of patients in a burns unit; after a period of 7 weeks three-quarters of the strains of Staph. aureus isolated from patients in the unit were resistant to neomycin, and after 22 weeks almost half of the patients in the burns wards were carrying the organism on their burns. When treatment with neomycin and kanamycin was stopped in the Burns Unit, neomycin-resistant strains gradually diminished in numbers and were no longer found in the ward after 6 months.

The neomycin-resistant staphylococci appeared during controlled trials of local neomycin and systemic kanamycin, and were much more frequently isolated from the burns of patients treated with these antibiotics than from patients in the control series.

During the previous 9 years local neomycin application had been used on many patients; though all staphylococci were tested for sensitivity to neomycin for a considerable part of this time, no resistant staphylococci were found.

All the neomycin-resistant staphylococci showed a pattern of inhibition by phages 6, 47, 54 and 77, and many also by phages 7, 53, 75 and 75B at 1000 R.T.D. No neomycin-sensitive staphylococci with this phage pattern were found at the time when resistant strains first appeared (though two such strains were found later); it seemed likely, therefore, that the resistant strain was introduced from outside the hospital. Preliminary tests of habituation to neomycin of sensitive strains with the phage inhibition pattern are described.

Back mutation to sensitivity was not found in tests on neomycin-resistant staphylococci.

A simple, laboratory scale, stirred system has been developed to examine conditions of culture necessary for optimum return of infective virus from explants of surviving bovine tongue epithelium, with particular bias towards large-scale procedures.

Control of hydrogen-ion concentration and aeration of the culture are emphasized.

The authors wish to thank Dr I. A. Galloway and Dr J. B. Brooksby for their helpful advice in preparing this paper, Mrs J. Lansley for her untiring technical assistance and Mr J. Goodridge who constructed the culture apparatus.