This paper reports on tests of cleaning and disinfection of stainless steel bedpans which have been coated with either a silicone grease or polytetrafluoroethylene (PTFE). The coatings were applied manually using an aerosol spray (silicone grease and PTFE), and by an industrial process (PTFE). Soils used comprised (i) British Standard Soil (B.S., 1966), (ii) human serum albumin labelled with technetium-99m (HSA-Tc), and (iii) a suspension of Streptococcus faecalis in broth. Tests of cleaning and disinfection were carried out in automatic washing and steam disinfector machines. Results show that aerosol spraying impairs the cleaning process but that bedpans coated by the industrial process with PTFE are superior to uncoated bedpans.

This study was carried out to investigate the effect of desert conditions on the pattern of delayed hypersensitivity to mycobacteria in school children aged 6–10 and 11–18 years. A new range of tuberculins prepared from ultrasonic lysates of living mycobacteria belonging to 12 different species was employed. Three centres were chosen for study, a sea port and two desert towns differing greatly from each other. The results obtained were compared with those of a previous study using the same reagents in Kenya.

As expected both the range of mycobacterial species to which the children reacted, the rate of acquisition of specific hypersensitivity with age and the total percentage of children reacting to individual reagents differed from centre to centre. The harsh desert conditions of Ajdabia produced the least, and the proximity of the people's dwellings to those of their farm animals in Kufra produced the most positive reactors to essentially environmental species. The greatest number of reactors to our Tuberculin were found in Benghazi where the cosmopolitan urban conditions probably lead to a high contact with open cases of tuberculosis. As assessed by skin test reactivity, immunization with BCG in Libya was much less effective than in Kenya. The interpretation of the differences between the results from the different test centres and between those for Libya and Kenya are discussed.

Comparison of bacterial counts of poultry carcass skin by the cotton swab and alginate swab methods showed no differences between the two sampling methods in total counts and Enterobacteriaceae counts. Also no differences were found in Salmonella isolations.

Selenite F broth prepared in the laboratory from single ingredients was found to be significantly more efficient than nutrient broth in the isolation of Shigella sonnei from human faeces. It was more efficient than direct plating on deoxycholate citrate agar for diagnosing Sonne dysentery in a local outbreak. The difference was significant. There was, however, no significant advantage for enrichment over direct plating when stools posted from Bristol to Cardiff were examined.

Laboratory prepared selenite F broth was preferable to the same medium purchased commercially from two different firms. The product of one firm was significantly better than that of the other.

Two methods of sterilization of laboratory prepared selenite F broth were studied. Seitz filtered selenite was less inhibitory to the growth of small numbers of Shigella sonnei. Sterilization by heating in free steam for periods of 15 mm and over impaired the ability of selenite F broth to allow multiplication of small numbers of Shigella sonnei.

The influence of colostrum-derived antibody to louping-ill virus on the course of experimental infection was investigated in lambs. Lambs that had high titres of antibody were refractory to infection. Lambs that had low titres of antibody did not develop a viraemia but either showed an antibody reaction or were sensitized as judged by the immune response, which was typical of an anamnestic response, after rechallenge. Animals that had no antibody 34–20 days before challenge had either no or very slight viraemia, but did develop an antibody response with titres as high as those of control lambs by day 21. Lambs that had been negative for longer periods responded in a similar fashion to controls.

These findings are discussed in relation to the occurrence of disease in lambs kept in louping-ill endemic areas. It is concluded that in such areas infections of lambs are likely to be of minor importance as a cause of mortality and of little epidemiological significance.

The toxic effect of certain products of Pseudomonas aeruginosa on guinea-pig alveolar macrophages has been studied in an attempt to account for the apparent infrequency with which certain strains of this species are associated with respiratory infection. Tests were carried out on strains derived from the respiratory tract, strains from infection at other sites, and strains from the inanimate hospital environment which were believed not to have been responsible for infection (‘environmental’ strains).

Haemolysin, pigments, enzyme-containing fractions, slime and cell-wall fraction all exhibited toxic activity against macrophages in an in vitro system, although for any given strain of Ps. aeruginosa the haemolysin was by far the most potent factor. The activity of this factor against macrophages was directly proportional to its haemolytic activity against human erythrocytes. The haemolysin fractions of environmental strains, which have previously been found to have little activity on erythrocytes, were also less active against macrophages than haemolysin preparations from ‘infective’ strains.

It is therefore postulated that the ability of a strain of Ps. aeruginosa to initiate respiratory infection may be related to the degree of haemolysin production. The activity of other fractions against macrophages is more variable, but they may contribute in different ways to the development of infection once entry into the lung has been achieved.

Foot-and-mouth disease virus (FMDV) survived in skim milk, cream and the pelleted cellular debris components of milk obtained from FMDV-infected cows after pasteurization at 72°C for 0·25 min. Virus was recovered from whole milk of infected cows after that milk was heated at 72°C. for 5 min. and from the skim milk component after it was heated at the same temperature for 2 min. Evaporation of the whole milk samples after they were heated at 72°C. for 3 min. did not inactivate the virus, but evaporation of infected skim milk samples after they were heated at 72°C. for 0·5 min. did inactivate the virus. FMDV survived in the cream component after it was heated at 93°C. for 0·25 min.

A new salmonella subgenus I serotype is described. Strain C.S. 1608/73, serotype 67: r: 1, 2, was isolated from activated sewage sludge and was assigned the name S. crossness. The serotype is biochemically atypical in its ability to utilize sucrose and this ability appears to be controlled by a transferable plasmid.

In many countries, the prevalent serotypes of Bordetella pertussis have changed from a mixture of types 1,2,3 and 1,2 (organisms possessing antigen 2) to a predominance of type 1,3. The timing of the change in different countries is shown to be related to the introduction of mass-vaccination with material rich in antigens 1 and 2 but weak in, or devoid of, antigen 3. In several parts of the world, there have been outbreaks of type 1,3 infection in fully vaccinated children.

Non-vaccinated communities in various parts of the world still show the pattern of serotypes which existed elsewhere before mass-vaccination.

In order to avoid the disappointments experienced in the past, it is essential that pertussis vaccine for use in previously non-vaccinated communities, like that for any other country, should be rich in each of the three antigens.

Attempts were made to stimulate acquired immunity to experimental Absidia ramosa infection in mice. Unprotected animals inoculated with large doses of A. ramosa spores frequently developed acute phycomycosis of the central nervous system. Mice previously exposed to sub-lethal doses of spores showed a high resistance to subsequent challenge with A. ramosa. No consistent increase in resistance was observed in mice vaccinated with killed A. ramosa spores, hyphal walls, intracellular mycelial antigens or various combinations of these, with Freund's incomplete adjuvant.

Antibodies to soluble mycelial antigens were inconsistently present in the sera of mice vaccinated with sub-lethal doses of viable spores. They were generally present in the sera of animals vaccinated with mycelial extracts or hyphal walls but not killed spores.

Delayed hypersensitivity reactions to A. ramosa mycelial antigens could usually be elicited by intradermal tests in mice exposed to viable spores but irregularly in those vaccinated with non-viable preparations. Positive reactions were also frequently given by older mice not deliberately exposed to A. ramosa.

Although mice previously exposed to viable A. ramosa spores were highly resistant to intravenous or intracerebral challenge with this fungus, they were more likely to develop persistent local granulomata on subcutaneous injection of spores than were unvaccinated animals.

More organisms were found on the paralysed hands of hemiplegic patients than on their unaffected ones. However, both showed considerably higher bacterial counts than did geriatric patients without paralysis. An infection rate for Cl. welchi of 15% was found in the paralysed hands.

Donor cattle infected with foot and mouth disease (FMD) virus subtype O1 were used to expose experimental cattle. The pharyngeal virus growth and viraemia patterns after contact exposure were quite different from those obtained after intranasal inoculation and suggested that the lower respiratory tract might provide an additional portal of entry for the virus. A tracheotomy was performed on experimental cattle to let the respiration bypass the pharynx, followed by exposure to FMD virus by different routes. The results confirmed that FMD virus can enter the bloodstream via the lung, followed by haematogenic infection of the pharynx and other replication sites simultaneously. These observations led to further experiments in which the intravenous route of infection was used to study the interaction of virus growth in the phayrnx, in other sites, and in viraemia.

Two statistical analyses are suggested to compare the success rates in isolating and identifying pathogenic organisms from specimens achieved by different laboratories participating in a quality control scheme. An example is given in which the analyses are applied to 25 laboratories that received 30 simulated specimens.

Viraemia is an important aspect of the pathogenesis of infectious diseases, but the mechanisms of entry and removal of virus from the vascular system particularly in natural hosts are poorly understood. The results of this study showed that the clearance of foot and mouth disease virus (FMDV) from the circulation of cattle and goats followed the general rules for the clearance of inert particulate materials and other viruses from the circulation. High doses of infused FMDV were cleared less efficiently than low doses, probably as a result of a depletion of the reticulo-endothelial system by the higher doses. FMDV was cleared from the circulation of cattle at a considerably slower rate than from the circulation of goats, but in both species significant individual variation in clearance was observed. These results could explain individual as well as species variations relative to the onset and duration of viraemia.

A radioimmunoassay (RIA) has been developed to measure antibodies against Brucella abortus in bovine serum and can be used in the diagnosis of bovine brucellosis. The RIA measures the amount of specific antibody of the IgG1 and IgG2 subclasses but is insensitive to 1gM, a characteristic which may make it more suitable than the complement fixation test (OFT) or the serum agglutination test for distinguishing infected animals from those which have been vaccinated with Br. abortus strain 19. The RIA is not subject to prozoning or ambiguous reactions, both of which interfere with the interpretation of the CFT.

Two tests for the estimation of Vi antibody in sera were studied and their validity in the screening of typhoid carriers was assessed. One was a modified Vi haemagglutination test in which Vi-coated glutaraldehyde-fixed erythrocytes were used as the antigen and Vi antibody resistant to treatment with 2-mercaptoethanol was titrated. The other was a fluorescent Vi antibody test in which acetone-fixed bacterial Vi cells were used as the antigen and the total Vi antibody was titrated. In both tests, the antigens used were stable so that standardization of the tests would not be difficult. The modified Vi haemagglutination test was found equally sensitive but more specific in giving less false positives than the conventional Vi haemagglutination test. The fluorescent Vi antibody test was however found superior to both tests not only in giving less false positives but also in detecting more typhoid carriers.

The serological responses of conventionally reared sheep were compared after vaccination with inactivated parainfluenza 3 (PI3) virus incorporated in three different adjuvants. Inactivated PI3 virus with the double-stranded RNA, BRL 5907 in an oil emulsion was shown to stimulate higher serum antibody titres over the first 5 weeks after vaccination than virus with and without BCG emulsified in oil. The ability of this vaccine to protect specific pathogen-free lambs against challenge with PI3 virus was examined in a second experiment. In this experiment the vaccine stimulated virus neutralizing and haemagglutination inhibiting antibodies in the serum. After intranasal and intratracheal inoculation with PI3 virus at challenge, vaccinated lambs showed no clinical illness and virus isolation was confined, except in one lamb, to the first two days. In contrast, unvaccinated lambs developed respiratory disease and virus was isolated daily for 7 days after challenge.

Restrained American cockroaches, Periplaneta americana L., were fed graded doses of Salmonella typhimurium ranging from 1·6 × 103 to 2·0 × 106, and their faeces assayed daily for the pathogen. Only 4 specimens out of 117 demonstrated multiplication of salmonellas, which was unrelated to size of input. When data of persistence regardless of actual numbers were expressed as percentage Salmonella-positive faecal-days, and these transformed to probits, a graph of percentage-positive faecal-days versus log dose allowed a calculation of the CD 50, or contaminative dose required for 50% of the faecal-days to be infective. The CD 50 for this cockroach species was 1·4 × 106Salmonella.

The soil fumigants methyl bromide, chioropicrin and Basamid or mixtures of Basamid and chloropicrin proved to be of no use in killing T. trichiura ova in soil. However, on untreated plots the eggs died at a rate such that only 20 % of the ova remained viable after 18 months.

Two interesting new phenomena have been observed in suspensions of T4Bo bacteriophage which were frozen to temperatures below the eutectic temperature of the salt (sodium chloride) in the suspending medium. Approximately 10% of the phage appeared to survive such a phase change as determined by plaque titre. However, exposure of these survivors to ultrasonic vibration or repeated freezing showed them to be hypersensitive and thus latently injured. The hypersensitivity was lost on incubating the phage at 37° C. for 3 hr. Furthermore, following a eutectic phase change, the surviving phage could be inactivated by rapid cooling to — 90° C. followed by slow rewarming. Such inactivation cannot be accounted for by accepted theories of freezing injury.