The effect of varying conditions of inoculation and incubation on the growth of type C influenza virus in the allantoic cavity of the developing chick embryo were investigated. It was found that the highest yields of both virus haemagglutinin and infectious virus were obtained following the inoculation of chick embryos at 8 days with subsequent incubation at 32° C. Using the chick embryo allantoic cavity for titration of infectious virus, growth curves of allantoically propagated virus under varying inoculation and incubation conditions were determined.

The presence of a heat-stable interferon-like inhibitor in allantoic and amniotic fluids collected from chick embryos infected with type C influenza virus was determined. This inhibitorwas characterized as an interferon and the ability of both live and ultra-violet-irradiated influenza type C virus to induce the substance was examined under various conditions.

The virus of Tanapox isolated from the lesions of patients during an outbreak of mild disease in Africa has been found to be indistinguishable in its biological and serological properties from a virus isolated from outbreaks of a pox virus infection in monkeys in primate centres in America. The natural hosts of this virus are believed to be African monkeys and ‘Tanapox virus’ is proposed as a suitable designation for the virus.

In BHK 21 cells infected with more than one TRIC organism the inclusions coalesce so that 30 hr. after infection only one inclusion per cell remains. Six hours after infection the cells are as susceptible to further infection as uninfected cells.

The relationship between multiplicity of infection and the yield of organisms and of polysaccharide was studied in BHK 21 cells infected with TRIC organisms. Although an increase in themultiplicity of infection resulted in an increase in the absolute number of organisms per culture, there was a decrease in relation to the number of infecting organisms. The amount of polysaccharide produced was independent of multiplicity of infection; it was not limited by the concentration of glucose in the medium. Polysaccharide leaked from cells and was slowly broken down in the culture medium.

In a comparative study of 24 different rubella virus strains, all but three formed small plaques in RK 13 cell cultures; of these one was the vaccine strain HPV-77, one was isolated from a congenitally infected infant, and the third was recovered from an adult who contracted severe rubella while handling this congenital strain. Whereas the plaque size of the vaccine strain was stable after further passage in cell culture, the plaque size of the other two rapidly diminished when the virus was passed in monkey kidney cells, and one of them was also reduced by passage in RK 13 cells. Cell culture passage of the typical small plaque strains did not result in altered plaque size.

Host ranges of members of four groups of male-specific RNA coliphages were determined by plating on hosts carrying various derepressed plasmids. An RNA phage originally isolated on Pseudomonas aeruginosa failed to form plaques on any of the strains of Escherichia coli.

This paper describes a search for Gram-negative bacteria in an operating theatre and the steps taken to reduce the level of environmental contamination.

A high rate of infection in clean wounds prompted a bacteriological survey. Potential sources of infection found, and the measures employed are described in the hope that others may be encouraged to examine familiar equipment critically and to improve hygiene even in old premises.

The choice, design, use and care of cleaning and sterilizing equipment were open to criticism. In particular, a currently popular floor-scrubbing machine provided a breeding ground for Pseudomonas aeruginosa and was distributing it in the theatre environment.

The complement-fixation test, as commonly used in the diagnosis of viral infections, was studied for its possible application to the diagnosis of whooping cough and the detection of antibody following pertussis vaccination. The results were compared with those obtained in parallel immunofluorescence tests. CFTs were performed on sera from 41 patients with whooping cough (Bordetella pertussis isolated), 125 vaccinated persons, and 618 controls; parallel tests by IP were made on sera from 24 cases of whooping cough, 36 vaccinated persons and 37 controls. Results of both tests correlated closely and showed that titres of diagnostic significance were seldom found in control sera. They also showed that, in patients suffering from whooping cough, antibody in a single specimen or a rise in antibody between paired sera was almost always demonstrated. Titres in general were lower in infants less than 6 months of age. IgG antibodies were involved in both tests. Although the number of sera tested was small both tests appear to be reliable as means of demonstrating the presence of antibody formed during the course of infection and after vaccination.

Extraction of membranes of Mycoplasma hominis with n–butanol showed that antigenicity was associated with thenon-lipid residue, which probably consisted mainly of protein, and not with the lipid itself.

Since many membrane proteins are hydrophobic, membranes were rendered soluble in various ways. Extraction with urea or phenol was the most successful, yielding extracts which were both antigenic and serologically reactive. The urea extract could not be fractionated by polyacrylamide disk electrophoresis or by column chromatography. However, serologically active components identified by gel diffusion were separated from detergent-lysed membranes by polyacrylamide disk electrophoresis. The activities of antisera against these fractions suggested that indirect-haemagglutinating or metabolic-inhibiting antibodies can be directed against several different membrane antigens. However, the antigens identified by gel diffusion probably do not represent all the components participating in indirect haemagglutination.

Treatment of membrane suspensions with heat, alkali, periodate and various enzymes showed that the four components identified by gel diffusion could be distinguished by their differing stabilities and properties. On the basis of their lability and susceptibility to proteolytic enzymes, two were identified as proteins.

Faeces of healthy adults and of children under the age of 5, none of whom were attending hospital or receiving antibiotics, were examined for the presence of antibiotic resistant coliform bacilli.

A higher proportion of children (67%) than of adults (46%) carried resistant strains and this difference was observed in both the rural and urban groups.

Rural members of both age groups more often carried resistant organisms than urban members. Among rural adults, the incidence of drug-resistant strains was 63 % in those whose occupation involved close contact with farm animals, compared with 29 % in those with other occupations. The survey took place before the implementation of the Swann Report could have influenced the use of antibiotics in animal foodstuffs.

Transmissible R-factors were demonstrated in 61 % of the resistant strains. The incidence of transmissible resistance was similar among adults and children in town and country.

Four hundred and thirty-eight overtly healthy adults on Tiree were screened for bacteriuria by dip-inoculum culture and a tetrazolium reductase test.

Dip-inoculum culture affords a simple and effective means of providing a service in quantitative urine bacteriology for communities remote from a laboratory.

The pattern of bacteriuria on Tiree is much the same as in other communities surveyed. Criteria are discussed for assessing the sensitivity of the tetrazolium test in terms of quantitative urine culture.

After the appearance of sporadic cases of enteritis due to Salmonella panama, baked ham from one supplier was implicated as the source of infection. No pathogenic organisms were isolated from the working surfaces of the factory involved or from samples of a day's bacon output, but S. panama was isolated from the factory sewers. Stool examinations of the 500 employees showed one man in the baked ham section to be excreting S. panama. He was removed from work and no further infections were reported from the district. The organism could no longer be found in the sewers.

Some weeks later, further infections were reported in the London and Southend areas, which could be traced to ham from the original source. Sewer swabs at the factory were again positive. A further examination of all the employees revealed three cases and 82 symptomless excretors. Eight of 192 family contacts were also found to be excretors. Trimethoprim-sulphamethoxazole appeared to have no effect on the carrier state.

Examination of the hams in cold store showed some to be infected with S. panama, and a number of these had been consumed in the canteen.

Subsequent examination of pigs at slaughter and pig food prepared locally failed to isolate S. panama. The source of infection at the factory is unknown.

Salmonella aberdeen was established as the cause of illness in 30 out of a herd of 90 milking cows. The illness was only moderately severe, and all animals responded to treatment.

The source of infection was considered to be human sewage effluent overflowing onto grazingland. There was no report of human infection in the area from which the effluent came.

A comparison has been made between the incidence of salmonellas in pigs and feeding stuffs in England and Wales and in Denmark. In Denmark there is veterinary legislation requiring the sterilization of imported and home produced feed ingredients of animal origin. There is no such legislation in England and Wales. In Denmark 0·3% of resterilized imported meat and bone meal was contaminated with salmonellas. This compared with 23% of meat and bone meal in England and Wales and 20–27% of other ingredients of animal origin. In England and Wales salmonellas were isolated from 7% of caecal samples and 6% of lymph node samples, while in Denmark they were isolated from 3% of caecal samples and 4% of lymph node samples. In England and Wales 25 serotypes were found in both pigs and feeds and these included nearly all the most prevalent human pathogens. In Denmark four of the six serotypes in pigs had been found in resterilized feed. One notable difference between the two studies was the very wide range of serotypes found in pigs in England and Wales and the narrow range in Denmark. A second was that Salmonella typhimurium formed 15% of all Salmonella strains isolated from pigs in England and Wales, and 60% of those in Denmark.

It is concluded that sterilization of animal raw ingredients in Denmark has reduced pig infections with types other than S. typhimurium that are foundin England and Wales, but not with S. typhimurium. It is possible that this is because S. typhimurium once introduced into pigs is able to establish itself more easily than other serotypes.

Salmonella infection on two pig farms and its relation to infection in pigs at slaughter was studied. On the first farm feed ingredients were mixed on the farm, and these included fish meal which was found to be contaminated with salmonellas. The feed was pumped to pigs in liquid form. There was a high salmonella isolation rate at slaughter when the contaminated fish meal was fed hi liquid feed, but it was significantly lower when no fish meal was fed to the pigs examined at slaughter. In some instances the same serotypes were found in fish meal and pig excreta on the farm and in caecal contents of the pigs at slaughter. No serotype was repeatedly isolated from any source and it appeared that the serotypes were not able to establish themselves in the pigs. It is concluded that infection found at slaughter originated on the farm where fish meal introduced and maintained infection. There was an opportunity for salmonellas to have multiplied in the liquid feed for several hours each day.

On a second farm environmental conditions were similar, but feed was given in the form of ready-made pellets and nuts. Salmonellas were not isolated from the feed. At slaughter there was a significantly lower isolation rate than on the first farm.

The incidence of salmonellas in pigs was studied in five farms and a bacon factory.

Persistence and spread of salmonella excretion in pigs in a breeding establishment is described. Salmonella excretor boars and sows were responsible for the spread and perpetuation of infection in the farm. The possibility of spreading salmonella infection between farms through the distribution of excretor pigs was studied. Infection persisted and was related to the initial state of excretion of the pigs while at the farm of origin.

The importance of feeding stuffs as a source of salmonella infection in pigs is discussed. Specially prepared heat treated pellets fed to the pigs prevented the introduction of salmonellas.

Yersinia enterocolitica serotype IX has been found to stimulate the production of vibriocidal antibody against Vibrio cholerae, particularly in Inaba serotype, in experimental rabbits and infected man to a significant degree. This activity could be absorbed by both Inaba and Yersinia antigens from anti-yersinia sera, but Yersinia antigen could not absorb vibriocidal activity from the anti-cholera sera, indicating a unilateral relation.

Vibrio agglutinating antibody, particularly against Ogawa, in anti-yersinia rabbit or human sera was found to be less liable to non-specific stimulation.

V. cholerae, while removing vibriocidal antibody, could not absorb the Yersinia agglutinin from anti-yersinia sera, suggesting that there is a different determinant for these two types of antibody activities.

The non-specific production of vibriocidal antibody by Y. enterocolitica type IX indicates the need for caution in the interpretation of the results of vibriocidal tests where such organisms are prevalent.

A comparison was made between a macrotechnique in tubes and a microtechnique in plastic plates for complement-fixation tests, using strains of three subtypes of the Asia 1 type of foot-and-mouth disease (FMD) virus. The results obtained with these techniques were found to be comparable and delineated the antigenic relationships of the three strains employed. The microtechnique was considered to be both economical with reagents and capable of similar accuracy and reproducibility to that of the standard method in tubes. It was concluded that the antigenic analysis of subtype strains of FMD virus can be conveniently carried out by the use of the microtechnique as described.

Variations in mortality attributed to birth injury and atelectasis in the 10 years 1958–67 have been investigated for each county borough of England and Wales. It became evident that diagnostic difficulties in separating these two causes must have been such that for statistical purposes they should be combined in a single rate.

Variables likely to affect the local rates such as the sex ratio of births, and rates of illegitimacy and immaturity as an ill-defined cause of death appeared to affect the mortality levels in certain towns but not sufficiently to account for the wide variations apparent in those levels. It is concluded that local surveys are necessary in the towns with highest rates to uncover differences in numbers of births in hospital, in obstetric techniques and in quality of medical care.