Variants of type A FMD virus from the Eastern Mediterranean region over the years 1964–72 have been shown to belong to a group distinct from the Western European strains as represented by A5 Westerwald. This group appears to derive from the A22 strain first recognized in 1964 and indicates the possibility of new strains supplanting old in the field.

Laboratory studies showed that few rabbit fleas (Spilopsyllus cuniculi (Dale)) transmitted myxomatosis after removal from wild rabbits (Oryctolagus cuniculus (L)) that had been infected for fewer than 10–12 days, irrespective of the virulence of the myxoma virus strain involved. Rabbits infected with fully virulent (Grade I) strains died within 10–15 days and few fleas from these hosts became infective; averaging all the samples taken, 12% of the fleas were infective. Also, few fleas acquired infectivity on individual rabbits which recovered from infection with attenuated strains; the mean was 8% infective. Rabbits which died between 17 and 44 days after infection had higher proportions of infective fleas at all sampling times; the mean was 42% infective. Male and female fleas transmitted virus with equal efficiency.

For rabbits infected with any of the attenuated virus strains the mean percentage of infective fleas was inversely related to the survival time of the host. Rabbits infected with moderately attenuated strains (Grades IIIA and IIIB) had, on average, the highest proportion of infective fleas; hence such strains have a selective advantage and have become predominant under natural conditions in Britain. The changes that might occur if there is an increase in host resistance to myxomatosis are discussed.

Intravenous provocation (IVP) tests demonstrated that hydroxypropylmethylcellulose (MC) was able to elicit anaphylactic signs in cattle vaccinated with foot-and-mouth disease (FMD) vaccine produced at one centre but not with similar vaccine produced at another. The former vaccine also provoked serum reagins which were demonstrated by passive cutaneous anaphylaxis (PCA) tests in goats.

Reaginic sera which reacted specifically with MC were used in PCA tests to screen samples taken serially from the vaccine production lines. The reactions observed suggested that a substance with MC or similar specificity was present in the antifoaming agent routinely added to vaccines.

The vibriocidal activity of Inaba and Ogawa antisera, from which cross-reacting agglutinin had been absorbed, was specific for Vibrio cholerae strains of the homologous serotype. No vibriocidal action against strains of the heterologous type was detected.

The sera appeared to be equally effective in killing organisms of different biotypes (classical, intermediate, and EITor), provided that these were of the homologous serotype (Inaba or Ogawa). However, they had been raised against strains of the classical biotype only; and sera resulting from immunization with other biotypes had not been prepared.

The implications of these findings in immunity to cholera are discussed.

Rhinovirus was recovered from the fingers of 16 of 38 volunteers and others, who were swabbed during the acute stages of their colds. Very low titres of virus were also recovered from 6 of 40 objects recently handled by infected volunteers, but not from the fingers of 18 non-infected subjects whose flat-mates were shedding virus. When rhinovirus from nasal secretions was dried on skin or other surfaces during laboratory experiments, approximately 40–99 % of infectivity was lost. Virus could be transferred from surface to surface by rubbing, the transfer being more efficient if it was carried out while the inoculum was still damp.

Volunteers could infect themselves if a moderately heavy dose (88 TCD50) of virus was inoculated on the finger and then rubbed into the conjunctiva or nostril, especially if the inoculum was still damp. From estimates of virus titres in nasal washings and on fingers, and of amounts transferred by rubbing, it was concluded that spread of colds is unlikely to occur via objects contaminated by the hands of the virus-shedder, but that a recipient might pick up enough virus on his fingers by direct contact with heavily infected skin or secretions to constitute a risk of self-inoculation via the conjunctiva or nostril.

An investigation into the cause of bacterial contamination of bottles of non-injectable water has been reported. A method of monitoring such bottles has also been described. The roles played by autoclave spray-cooling water and inadequate bottle seals in the contamination of fluids have been examined. Possible methods of reducing the risk of contamination are discussed and the design of an improved method of closure of sterile bottled fluids is stressed. Bacteriological examination is shown to be a more accurate index of the true rate of contamination than measurement of dye concentrations of bottle contents.

A total of 21 rubella seronegative children vaccinated subcutaneously with Wistar RA 27/3 strain live attenuated rubella vaccine in a family study of vaccine virus transmissibility were reviewed after 6 years. Haemagglutinating inhibiting (HAI) antibody titres of sera collected 46 days, 2 years and 6 years after vaccination were compared. Antibody titres in the vaccinated subjects were not significantly influenced by time, infection in susceptible siblings or revaccination.

The results of testing sera from 111 patients with rubella-like illnesses and 283 contacts of patients with rubella-like illnesses are described. A sensitive haemagglutination-inhibition test was used in conjunction with fractionation of serum proteins when this was indicated. It was concluded that the testing of serum protein fractions for IgM and IgG rubella antibody greatly increased the effectiveness of laboratory diagnosis. Evidence is presented that during the study period subclinical rubella was relatively uncommon in adults and that the accuracy of clinical diagnosis was high.

A standard hand-wash sampling technique was compared with a simple fingerstreak sampling method in assessing the relative effectiveness of a number of alternative preparations used for disinfecting the surgeon's hands (alcoholic 0-5% chlorhexidine, alcoholic 0-1% tetrabrom-o-methyl phenol, a 4% chlorhexidine detergent solution, aqueous 0-5% chlorhexidine, 2% 'Irgasan' detergent solution and, as control, bar soap). There was a fairly good correlation between the results of assessment by the two methods after a single disinfection and after six disinfections, three on one day and three on the next. Significant differences were shown in 21 comparisons between treatments when the hand-wash sampling test was used, and 16 of these comparisons also showed a significant difference by the finger-streak test.

Staphylococcus aureus was found in hand samplings from 5 out of 8 nurses in the Burns Unit of Birmingham Accident Hospital by the hand-wash sampling method and from 2 of the same 8 nurses by the finger-streak method; the numbers were small, and no Staph. aureus were isolated from the same hands after 1 min. wash in 70 % ethyl alcohol. Similar sampling on 29 nurses in other wards showed Staph. aureus on 3 nurses (one in large numbers) by the hand-wash technique and on 1 nurse by the finger-streak test; in only 1 nurse whose hands showed Staph. aureus before disinfection was the organism found, by hand-wash sampling, after disinfection.

Parallel sampling of nurses' hands after washing with soap and water and after disinfection with 95 % ethanol showed larger numbers of Staph. aureus in a hospital for skin diseases than in a general hospital, and a lower incidence and somewhat lower density of Staph. aureus after ethanol treatment than after washing with soap and water; Gram-negative bacilli, on the other hand, were commoner on hands in the general than in the skin hospital, and present in much smaller numbers after disinfection with ethanol than after washing with soap and water.

Antibiotic sensitivity tests showed the frequent recurrence on the hands of some nurses of multi-resistant Staph. aureus with resistance patterns similar to those found in infective lesions in some of the patients; different sensitivity patterns were usually found in staphylococci isolated from the nose. Even in wards where many patients were infected, carriage by nurses' hands of a particular strain ofStaph. aureus did not seem to last for more than a few days.

A study of the incidence of diphtheria in the State of Victoria, Australia, was carried out. Numerical analysis of the characteristics of 264 strains of Corynebacterium diphtheriae isolated between 1962 and 1971 placed them into 18 varieties plus six strains which were unique in their combination of reactions to the characteristics examined. During the 10-year period, some varieties appeared inter mittently and were recognized by certain defining characteristics but exhibited a gradual change in their antigenic structure. In contrast, when the outbreaks were examined over shorter periods of time, a number of varieties and single strains were found which differed greatly from each other yet possessed the same major serotype antigen. These findings are discussed in terms of a 'one-parent' concept in which the varieties and single strains represent phases of a common ancestor.

By inspection and analysis of the characteristics of the strains, certain associations were apparent. For instance, a correlation was found between the antigenic structure of the organism and the colonial appearance on tellurite blood agar. Similarly, correlation was observed between bacteriophage type, diphthericin type and biochemical activity in that a strain which was highly active in one of the properties was also very active in the other two.

The Limulus test detected endotoxins in the plasma of burned and unburned mice infected with different species of gram-negative bacteria. Individual strains of different species of gram-negative bacteria produced different amounts of endotoxin in the plasma of infected mice. Plasma from mice given lethal infections showed very high concentrations of endotoxin. Low concentrations of endotoxin in the plasma were tolerated by mice but high concentrations were invariably fatal. A polyvalent pseudomonas vaccine reduced endotoxin in the plasma of mice given lethal infections of Pseudomonas aeruginosa.

Comparative clinical trials of live attenuated and detergent-split subunit influenza virus vaccines were undertaken with 1048 volunteers in Western Australia. Volunteers were divided into three main groups, each of which received either live virus vaccine or a saline control administered intranasally, or subunit vaccine injected subcutaneously. No differences were recorded between the three groups in their post-vaccination symptoms. Serum samples were collected at various times up to 50 weeks after vaccination, and antibody titres were measured by haemagglutination-inhibition (HI) tests and, for 231 volunteers, by virus neutralization tests. The two vaccines were almost equivalent in inducing seroconversion in vaccinees with pre-trial HI titres of 96 or less, but the subunit vaccine stimulated a higher geometric mean HI antibody titre. The longevity of the HI antibody response was greater for the live virus vaccine. The height of the response and the longevity of neutralizing antibody were the same for both vaccines. Both vaccines provided a high degree of protection against epidemic A/England/42/72 influenza, and some protection against A/Port Chalmers/1/73 influenza.

Chickens in groups of 40 were infected orally with a nalidixic acid-resistant mutant of Salmonella typhimurium and then fed continuously on diets containing ampicillin, chloramphenicol, furazolidone, neomycin, oxytetracycline, polymixin, spectinomycin, streptomycin or a mixture of trimethoprim and sulphadiazine. The amount of S. typhimurium excreted in their faeces was estimated at intervals by culture on brilliant green agar containing sodium nalidixate, both direct and after enrichment in selenite broth; the amount of Escherichia coli excreted was estimated by culture on MacConkey agar. The feeding of diets containing 500 mg./kg. of ampicillin, furazolidone, neomycin, polymixin, spectinomycin or streptomycin or 100 mg./kg. of trimethoprim and 500 mg./kg. of sulphadiazine for 46 days reduced to a varying degree the amount of S. typhimurium and E. coli excreted, the greatest reduction in S. typhimurium being brought about by the last treatment. The effect was less obvious when the concentration of the antibiotics in the food was decreased fivefold. An important reason for the very limited effect of some of the antibiotics was the emergence of antibiotic-resistant populations of S. typhimurium and E. coli. High concentrations of antibiotic-resistant organisms also arose in the faeces of the chickens fed diets containing tetracyclines and chloramphenicol, treatments which had no apparent effect on the amount of S. typhimurium and E. coli excreted. Much of the antibiotic resistance encountered was determined by R factors, a particular R factor usually being found in the E. coli populations of individual chickens before it was found in their S. typhimurium populations. No S. typhimurium or E. coli were isolated that possessed R factors determining resistance to polymixin, furazolidone or trimethoprim. No S. typhimurium or E. coli were isolated that were polymixin-resistant and no S. typhimurium that were furazolidone-resistant. The few trimethoprim-resistant S. typhimurium isolated were thymine-dependent.

The feeding of diets containing the higher concentrations of trimethoprim/sulphadiazine, neomycin, furazolidone or ampicillin for 9 days reduced the amount of S. typhimurium excreted. After the withdrawal of these diets, the amount of S. typhimurium excreted increased to the numbers found in chickens given ordinary diets throughout; the chickens that had been given trimethoprim/sulphadiazine or furazolidone did not remain faecal excreters of S. typhimurium longer than the chickens that had been given ordinary diets. Similar results were obtained with trimethoprim/sulphadiazine when the start of the 9-day treatment period was delayed for an extra 9 days or when it was extended to 18 days.

Bacteriological tests alone are not capable of predicting the keeping quality of cream, since taints can develop which are due to non-bacterial action. When spoilage is due to bacterial growth, the water agar test was found to be more accurate than the other tests that were examined.

Studies in a newly built hospital furnished with complete air conditioning where most of the patients are nursed in 6-bed rooms showed that the transfer of air from one patient room to another was very small, especially when there was substantial flow of air in a consistent direction between the patient rooms and the corridor, and that the direct transfer of airborne particles was even less. There was, however, no evidence of any reduction in the rates of nasal acquisition of Staphylococcus aureus compared with those to be found in naturally ventilated hospitals.

The numbers of Staph. aureus found in the air of a given room that appeared to have originated from patient carriers in other rooms were many times greater than could be accounted for by direct airborne transfer. Although there was evidence that many carriers were not detected, detailed study showed that this excess transfer to the air of other rooms was genuine. It seems probable on the basis of investigations in this hospital and elsewhere that this excess transfer occurs in-directly, through dispersal from the clothing of the nursing and medical staff into the air of another room of strains with which their outer clothes have become contaminated while dealing with patients.

Reduction in direct airborne transfer of micro-organisms from one room to another, whether by ventilation or other means, can only be of clinical advantage if transfer by other routes is, or can be made, less than that by the direct airborne route.

Groups of 45 chickens were fed continuously on diets containing 10 or 100mg./kg. of different ‘growth-promoting’ antibiotics and infected orally with a nalidixic acid-resistant mutant of Salmonella typhimurium. The amount of S. typhimurium organisms excreted in their faeces was estimated by culturing them at weekly intervals and in a standard manner on plates of brilliant green agar containing sodium nalidixate, both direct and after enrichment in selenite broth.

All of four groups fed diets containing 100 mg./kg. of nitrovin in three different experiments excreted much larger amounts of S. typhimurium than did groups fed antibiotic-free diets. In some, but not all, experiments, larger amounts were also excreted by groups fed diets containing 10 mg./kg. of nitrovin or 10 or 100 mg./kg. of flavomycin or tylosin. Feeding diets containing 10 or 100 mg./kg. of virginiamycin or bacitracin either did not influence or slightly ncreased the amount of S. typhimurium excreted.

Two groups fed continuously on diets containing 100 or 500 mg./kg. of sulphaquinoxaline for 44 days excreted smaller amounts of the S. typhimurium organisms than did groups fed antibiotic-free diets; no sulphonamide-resistant organisms of the S. typhimurium strain were isolated from the faeces.

Using a laboratory downward displacement vertical autoclave with the help of thermocouples recorded on a 12 point multichannel strip recorder, the risk of failing to sterilize laboratory discard buckets has been demonstrated. The use of proper temperature and time controls can prevent this risk.

A load in a bucket with perforated sides is more easily sterilized than in a solid bucket. Wire baskets, where appropriate, facilitate the sterilizing practice. The addition of water to a bucket does not reduce the time of heating up.

It is desirable that sealed bottles of media should not be sterilized in simple downward displacement autoclaves, but if used, strict monitoring of temperatures and times is essential both in the heating up stage and especially in the cooling stage. The temperatures in bottles are slow to rise and very slow to fall. Bottles at high temperature 80–405° C. or over have a high internal pressure which can allow the bottles to explode when subjected to thermal shock if removed too early.

It is suggested that all laboratory autoclaves should have a load temperature simulator or similar device to control the temperature of the load during the cycle automatically. For the sterilization of fluid media, it is suggested that, in addition to a simulator there should be accelerated cooling to reduce damage to the media and, what is more important, to rapidly bring down the temperature and thus the internal pressure in the bottles to a safe level. The opening of the sterilizer door or lid should be automatically controlled by the load temperature simulator.

This study on Kenyan schoolchildren aims to elucidate the effect of contact with environmental mycobacteria on the development of specific delayed hyper-sensitivity. A series of 12 skin test reagents was employed; eleven of them were prepared from extracts of living mycobacteria and the last was the P.P.D. RT 23. Eight of the new tuberculins were prepared from mycobacteria recovered from the East African environment. A total of 8641 tests were carried out on 4320 children between the ages of 6 and 17 years in four townships. Two of these townships were in fertile agricultural areas and two were in the desert. Just over 80% of the children had received BCG immunization.

The results obtained showed that increasing age, geographical locality and BCG immunization all had a profound effect, and socioeconomic background had some effect, on the pattern of reactivity to the various reagents. The rationale behind the use of the series of new tuberculins and the results obtained with them are discussed in relation to the interacting effects of the factors complicating these results.

The names Citrobacter koseri, Levinea malonatica and Citrobacter diversus are synonymous. As a result of the study of representative strains of these organisms an antigenic scheme comprising seven O antigens has been proposed. The examination of a further 165 strains from clinical sources suggests that an additional seven antigens should be included in the scheme. The serological and biochemical reactions of the test strains for all 14 O antigens are described.

Nose and throat swabs, for culture of Haemophilus influenzae type b, and blood samples, for measurement of antibodies specific for that serotype, were collected from members of 28 families from which children had been admitted to hospital with acute H. influenzae type b infections (mainly meningitis or epiglottitis). The patients with meningitis were younger than those with epiglottitis and had more siblings, with a marked predominance of sisters. Investigations within a few days of admission of the affected children to hospital detected carriers of H. influenzae type b (19 altogether) in 13 of the 28 families, including 9 of the 13 families with 3 or more children. Members with raised antibody titres for H. influenzae type b (suggesting the presence of the organism for at least a few weeks) were found in 17 of the 25 families from which blood samples were obtained, including all 11 families with 3 or more children. Most of the patients probably acquired their infections from within their own families, and siblings under 11 years old were of predominant importance both as carriers and as potential sources of the patients' infections. Persistence of the organism within families for up to 6 months was demonstrated. Possible reasons for the difference in age-incidence between haemophilus meningitis and epiglottitis and for the occurrence of the former in babies with older sisters are suggested, and also a possible connexion between the results of this survey and the likely value of immunization against H. influenzae type b.