Strontium chloride B medium and E.E. broth have been found effective in the recovery of Edwardsiella, Salmonella and Arizona species from the cloacal contents of tiger snakes (Notechis scutatus). Strontium chloride B medium was superior to E.E. broth.

At least one bacterial species was detected in each of the 60 reptiles examined, and all three organisms were recovered from each of 29 snakes on a single examination.

Strontium chloride M, strontium selenite and Rappaport enrichment media and bismuth sulphite agar, although satisfactory for the isolation of Salmonella and Arizona species, were found unsuitable for Edwardsiella tarda.

1. The European rabbit flea Spilopsyllus cuniculi (Dale) bred successfully in wild rabbits on three properties in New South Wales and, within two breeding seasons, almost every rabbit shot within a quarter of a mile of a release site was infested.

2. It was demonstrated that the flea transmitted myxoma virus in the field.

3. In areas where more than 75 % of the rabbits shot at the beginning of the breeding season were flea-infested and myxoma virus was present, populations failed to show the expected summer build-up.

Viable counts of beta-haemolytic streptococci per ml. of saliva were made in the following groups: (1) children with acute streptococcal sore throat, (2) children with acute non-streptococcal sore throat, (3) children who had no sore throat but were streptococcal throat carriers, (4) children who neither had a sore throat nor were streptococcal throat carriers.

The mean counts from cases of streptococcal sore throat and from streptococcal carriers were respectively 1·4 × 106 and 2·5 × 105 per ml.

In a comparison of the efficiency of the throat swab, sublingual swab and specimen of saliva in isolating beta-haemolytic streptococci from the upper respiratory tract, culture of saliva produced the best results.

Bacteriological monitoring of penicillin therapy in 30 children with streptococcal sore throats was performed by means of salivary and throat-swab culture, on the first, third, fifth and ninth days after therapy had started. Counts of beta-haemolytic streptococci per ml. of saliva were also performed.

Results showed that salivary culture and estimation of the numbers of beta-haemolytic streptococci in the saliva were much more sensitive indices of the effectiveness of penicillin treatment than throat-swab culture.

When fresh animal serum was dropped onto seeded mycoplasma agar plates, inhibition of growth frequently occurred. This effect was dependent on the mycoplasma serotype and on the animal species from which the fresh serum came. This activity of fresh animal serum was heat-labile and would not diffuse through the agar medium. Growth of all the porcine mycoplasma serotypes was inhibited by fresh sheep serum. M. hyorhinis, M. hyopneumoniae, B 3 and the P 45 strains were insensitive to fresh horse serum. The addition of fresh horse serum to specific M. hyorhinis rabbit antiserum-impregnated disks appeared to have a synergistic effect and the combination of M. hyorhinis antiserum-impregnated disk and fresh horse serum always inhibited the growth of M. hyorhinis strains.

After subcutaneous vaccination of rubella sero-negative children with Wistar RA 27/3 rubella vaccine, haemagglutination-inhibiting antibody titres were compared in sera taken 46 days and 2 years after vaccination. Antibody titres were well maintained in the absence of any known exposure to natural infection.

Scotland and Ireland have the highest death rates from multiple sclerosis and high rates are recorded in an area extending south-eastward from Britain through central Europe. The rates tend to diminish with rising latitude and longitude. In England and Wales the county boroughs with notably high rates during 1958–67 were mostly textile towns with cotton and wool mills, situated in the area recording the lowest average levels of sunshine. In the London area mortality from multiple sclerosis was high in those western boroughs and adjacent counties most exposed to the noise of aircraft using the airports of London. The geographical pattern in England suggests that noise and vibration of particular kinds may be a factor in causation along with a climatic factor, but this hypothesis is speculative until further evidence is found to support it.

Hysterectomy-produced, colostrum-deprived (HPCD) pigs and naturally born, enzootic-pneumonia-free (EPF) pigs were compared with respect to their susceptibility to two strains of enzootic pneumonia induced by intranasal inoculation of suspensions of ground pneumonic tissue. All but one of the HPCD pigs developed enzootic pneumonia, whereas the EPF pigs commonly failed to develop the disease; secondly, the pneumonic lesions were more extensive in the HPCD pigs.

When the dose of inoculum was increased in EPF pigs, the resulting pneumonic areas were larger.

In a small, in-contact experiment the disease was also more readily transmitted to HPCD pigs than to EPF pigs.

This study describes the results of attempts to grow viruses from per-nasal swabs taken from 136 children with clinical pertussis.

Altogether 37 strains of a variety of different viruses were isolated. Adenovirus was the most frequent, making up 30 % of the total. Besides these, herpes simplex, measles, influenza A2, influenza B, mumps, poliovirus and respiratory syncytial virus were detected.

Bordetella pertussis was isolated from 22 % of the cases.

It appears that a pertussis-like syndrome can be caused by many agents besides Bord. pertussis and an accurate diagnosis requires laboratory confirmation.

The effect of oral administration of antibiotics on the intestinal flora of conventional mice and their resistance to colonization by orally introduced Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa was studied. Colonization resistance (CR) was expressed as the log of the oral bacterial dose followed by a persistent take in 50 % of the contaminated animals. The intestinal flora was virtually eliminated by the antibiotics and this elimination was accompanied by a precipitous fall of CR. CR gradually returned to normal values during the period of repopulation of the intestinal tract by the organisms surviving the treatment. Antibiotic treatment resulted in the disappearance of Enterobacteriaceae, enterococci, staphylococci and yeasts and, under appropriate housing conditions, the animals remained free of these organisms indefinitely. Germ-free mice contaminated with the intestinal flora of an antibiotic-treated animal and their offspring housed in a germ-free isolator showed high values of CR. Their intestinal flora consisted of anaerobic bacteria only. Apparently, these anaerobes are responsible for CR in these and in conventional mice.

To facilitate the isolation of anaerobes from cultures in which swarming organisms were present Roux flasks were adapted to provide anaerobic conditions. Using these flasks, five species of anaerobes were isolated from the caecum of mice resistant to colonization with Escherichia coli and other Gram-negative organisms. These species accounted for the majority of organisms seen in films of caecal material. No aerobes were isolated and the flora of these mice apparently consisted of a limited number of anaerobes representing part of the intestinal flora of conventional mice. Three of the species were clostridia and another was identified as Propionibacterium acnes. One species resembled Catenabacterium but was not identified. One of the Clostridium species could only be isolated when the medium was supplemented with yeast extract and vitamins. This species sporulated on media with ammonium phosphate as the source of nitrogen; tryptone completely suppressed sporulation.

Records of seven common-cold outbreaks on the island of Tristan da Cunha are compared with the corresponding time courses given by the mathematical model of Kermack & McKendrick (1927) and with an alternative model that directly involves a constant average duration of individual infection. Using computer simulation techniques the latter model is shown to be preferred and is then closely matched to the field data to obtain values for the model parameters. Consideration is then given to the intensity of epidemics predicted by the model and to the distribution of the actual epidemics relative to the theoretical epidemic threshold.

The rates of decline (half-lives) of maternally acquired antibodies of two different specificities in a group of infants were found to be highly variable, ranging from 18 to 192 days for parainfluenza type 3 antibody (54 infants) and from 15 to 251 days for influenza A2 antibody (nine infants). For antibodies of both specificities approximately 75% of the half-lives were between 15 and 60 days. With parainfluenza type 3 antibody, and possibly with influenza A 2 antibody, the half-lives were inversely proportional to the initial antibody titre of the babies' sera. This relationship could be described by a rectangular hyperbola. Babies with high antibody titres at birth lost this antibody rapidly whereas in babies with low initial titres antibody declined over a longer period.

The half-lives of parainfluenza type 3 antibody and influenza A 2 antibody were compared with that of rubella antibody in the same group of infants (previously published). Maternally acquired viral antibodies of different specificities did not necessarily decline at similar rates in any given child. In nine infants, maternally acquired antibodies of two different specificities (rubella and parainfluenza type 3) declined at significantly different rates in the same child. It is suggested that although the half-life of antibody of a given specificity is related to its concentration in the serum, it is independent of the level of serum antibodies of other specificities.

The distribution of neutralizing antibody to Yaba virus and 1211 agent in the sera of three Asian and one African monkey species was examined.

Cynomolgus (Macaca irus), bonnet (M. radiata) and rhesus (M. mulatta) monkeys possessed antibody to Yaba virus at incidences of 19·9, 8·4 and 0%, respectively. In African green monkeys (Cercopithecus aethiops) the incidence was as high as 76·4%.

As for 1211 agent, no Asian monkeys had neutralizing antibody and 5·5% of African green monkey sera neutralized the virus.

Rapid spread of methicillin-resistant staphylococci (MeRS) in a children's hospital is described. Within 4 months of the first isolation MeRS had been isolated from infections in all clinical units. MeRS were also regularly isolated at the out-patient department. Protective isolation of one of the clinical units had no effect on the infection rate by MeRS. The use of antiseptics (Hexachlorophene and chlorhexidine) and gentamicin nose cream in children and staff members in three out of five clinical units resulted in a significant reduction of the prevalence of nose colonization by MeRS in children. In staff members a non-significant reduction of the prevalence of colonization and a significant reduction of the acquisition of MeRS was found. After a few months the infection rate decreased to zero in the units where the measures were introduced. It remained unchanged in the other units. Phage typing of two sets of strains collected at an interval of 6 months showed that the infections were mainly caused by two endemic strains of MeRS. The majority of the infections caused by MeRS was of minor importance. In 16 % of the infections a strain was isolated repeatedly and for more than 1 week. After the introduction of antiseptics a relative increase of infections by Gram-negative bacteria was observed. The significance of this phenomenon is discussed.

The action of trypsin and pronase on the haemagglutinins and neuraminidases of eight strains of influenza virus has been examined.

The haemagglutinins of all the strains were highly susceptible to digestion by pronase but there were great variations in resistance to trypsin.

The neuraminidases of the eight strains were of three types. The neuraminidases of the A1 strains and the DSP strain of virus A were highly susceptible to destruction by both enzymes. The neuraminidases of the PR 8 and Swine strains showed partial resistance especially to trypsin, while the A 2 strains and the lee strains of virus B possessed neuraminidases that were completely resistant to both trypsin and pronase.

Proteolytic enzymes released free neuraminidases from the A 2 and lee viruses the morphology of which was different from that of neuraminidases released by detergent treatment.

Thirty-three adults were vaccinated subcutaneously with Wistar RA. 27/3 (live attenuated) rubella vaccine at the Wellcome Research Laboratories, Beckenham. All subjects with pre-vaccination haemagglutinating-inhibiting antibody titres of 1/20 or less and three of seven subjects with pre-vaccination titres of 1/40 showed at least fourfold rises of titre. Reactions encountered were mild and of short duration.

A single dose of inactivated louping-ill oil-adjuvant vaccine elicited a serologically detectable immune response in sheep lasting for at least 1 year. These sheep when exposed to a natural focus of louping-ill virus were completely protected from clinical disease and 1 year after vaccination were able to pass on a substantial maternal immunity to their lambs.

Twenty-nine per cent of unvaccinated sheep, exposed at the same time, died from clinical louping-ill; half of the survivors showed positive sero-conversion and became immune, while the other half remained susceptible. The incidence of fatal encephalomyelitis in sheep which were known to have circulated virus exceeded 50% in 2 out of 3 trials conducted simultaneously in different locations in Scotland in 1969.

Clinical salmonellosis in cattle is infrequently recorded in Botswana, the majority of salmonella isolations being made from apparently healthy animals. A salmonella carrier rate of 6·7% was found in testing faeces samples from 89 apparently healthy cattle. A total of 35 salmonella serotypes were isolated from specimens of bovine origin. Salmonella dublin was isolated infrequently, possibly in part because of prophylactic vaccination.

A subclinical infection of Salmonella typhimurium in a broiler flock was investigated and attempts were made to eradicate the infection by treatment with furazolidone. One-quarter of the chickens were still infected after they had been through the processing plant. Washing in heavily chlorinated water reduced the number of contaminated carcasses. Infected chickens were also found in four other companion flocks on the same farm.