A transportable surgery cross-flow unit has been tested under ‘operational conditions’. By the use of artificial aerosols and a volunteer surgical team, or dummies, it was found that, at an air velocity of 0·45 m./sec., a detectable transfer to above the table occurred only when quite highly concentrated aerosols (of more than 103·6 bacteria/m.3 of air or more) existed underneath the table. The short disappearance time under these conditions and the quite stable flow pattern above the table found when a surgical team was working, standing along both sides of the table, make it unlikely that an aerosol of detectable concentration can develop during surgery, at this site. The chance that particles, liberated from the heads of the surgical team, settle on the table, was found to be strongly reduced when a cross-flow tunnel operated at an air velocity of 0·45 m./sec. The transfer from outside the unit to the inside was prevented by closing the upper part of the open front side.

Four calves were infected with 2·4 × 108S. dublin and penned separately. Fluctuations in environmental temperature did not affect the symptoms of the disease or the duration of excretion. Faecal samples were superior to rectal swabs for detecting excretors.

After transport stress, Salmonella was isolated from several organs at slaughter in an excreting calf, and uninoculated control calves became cross-infected. During slaughter, carcasses became contaminated on their surfaces. From one contaminated carcass Salmonella was recovered after chilled storage at 0° C. for 1 week and also after freezing at − 20° C. for 1 month.

Calves with a serum ‘H’ titre of 1/160 developed a chronic form of salmonellosis after infection with S. dublin. Their growth rate was severely retarded by this illness. An aerogenic strain of S. dublin was found to be much more virulent than an anaerogenic strain. Faecal samples were superior to mouth swabs in detecting animals carrying S. dublin.

During transport two uninoculated calves became infected and after transport stress, latent carriers of S. dublin with faecal samples negative for Salmonella for 5 weeks, restarted excretion. At slaughter Salmonella were isolated from viscera and organs and from the surface of five of six carcasses.

In the province of Voyvodina 18 cases of post-vaccinal encephalitis have been recorded, three of which were fatal.

The estimated morbidity rate was 0·6 per 105 after revaccination, and 3·9 per 105 after primary vaccination. The virological studies described, as well as other findings referred to in this report, are consistent with the possibility of an autoimmune aetiology of the post-vaccinal encephalitis cases observed.

Revaccination between 2 and 5 years after the last vaccination induced higher complement-fixation titres than revaccination 7–63 years after the last vaccination. The highest CF titres were reached during the 3rd to the 5th week after vaccination.

Fifty-two serum samples, taken 137 or more days after a successful vaccination, all showed CF titres lower than 1/2.

In a group of successfully vaccinated persons with no post-vaccinal complications, 65 out of 66 had a successful ‘take’ after one or two subsequent vaccinations.

Sera of persons receiving primary vaccination showed significantly lower CF titres than sera of revaccinated persons. Cases of post-vaccinal encephalitis showed greater antibody response than uncomplicated successfully vaccinated cases in both the primary vaccination and revaccination groups. The antibody response in revaccinated persons with post-vaccinal encephalitis was greater than that in the group of successfully revaccinated cases without encephalitis.

A group of 26 naturally hyporeactive persons completely failed to ‘take’ even after vaccination repeated between 3 and 10 times (average 5 times per person). The frequency of seropositives in this group, and the height of their CF titres, were significantly lower than in the group of successfully vaccinated persons. These findings support the view that untreated persons who repeatedly fail to ‘take’ with the vaccine must not be considered immune.

In vaccinated persons treated with immunoglobulin (with or without simultaneous treatment with Marboran) antibody production was apparently diminished. Treatment of patients with Marboran significantly lowers the capacity of the vaccine to ‘take’.

An epidemic of acute haemorrhagic conjunctivitis occurred in Morocco in 1970–1. It was caused by an enterovirus which appeared to be a new antigenic type similar to a virus isolated in South East Asia during the same period.

In the period 1960–70 meat and poultry products caused over 70% of successfully investigated outbreaks of human salmonellosis. The number of human incidents of salmonellosis declined from 1960 to 1966, but then more than doubled between 1966 and 1971. This increase was mainly due to a threefold increase of incidents of salmonella serotypes other than Salmonella typhimurium. The serotypes which increased most and contributed significantly to this trend were S. enteritidis, S. panama, S. Stanley, S. virchow, S. Agona, S. 4,12:d:- and S. indiana.

Strong evidence exists that these serotypes have a path of infection from animal feedingstuffs to the pig and poultry animal reservoirs to pork and poultry foods to man. Cattle appear to be a less important source than pigs and poultry and this may be because the nature and content of their feed is different.

The importance of the control of the pig and poultry reservoirs of salmonella infections is stressed and a significant role of animal feedingstuffs in the maintenance of these reservoirs strongly suggested.

Neuraminidase (N) can be extracted from virus particles of influenza B strains by treatment with trypsin, in a form which is free from the viral HA and has specific immunological activity. The N antigen of B/LEE/40 behaves differently from that of 1965–6 strains in gel diffusion and enzyme inhibition tests with animal antisera raised by infection or by artificial immunization with the homologous or heterologous strains. The frequency and titres of NI antibody detected in human sera by B/LEE antigen are different from those found with antigen from B/Eng/ 13/65. The latter antibody appears to contribute to the effect of serum HI antibody in protecting volunteers exposed to a deliberate intranasal challenge infection of the B/Eng/13/65 strain.

In mice and in monkeys, ‘selective’ elimination of Enterobacteriaceae species from the digestive tract of animals with a sensitive flora was accomplished by oral treatment with nalidixic acid (1 mg./g. body weight in mice and 0·4 mg./g. body weight in monkeys). During treatment, the concentration of enterococci (and also of Candida albicans in the monkey) remained unaltered. This indicates that the fraction of the anaerobic microflora which is responsible for the colonization resistance of the digestive tract is not affected by the treatment. An important consequence seems to be, that elimination of yeast and fungi with fungistatic drugs can be started at the same time as elimination of Enterobacteriaceae is attempted.

Although we have failed to produce either paroxysmal cough or vomiting in rhesus monkeys, cynomolgus monkeys and marmosets, we have found in marmosets several features of pertussis infection similar to those seen in children with whooping cough: catarrh, persistence of colonization of the naso-pharynx with Bordetella pertussis for 4–11 weeks, change of serotype during colonization and inability of type 1 organisms to establish themselves as the predominant serotype.

As in children, we have found that intramuscular vaccine of type 1,2,3 was more effective than type 1,2 in preventing persistent infection with the currently prevalent serotypes 1,2,3 and 1,3. A mixed vaccine (1,2,3 and 1,3) seemed to produce agglutinin 3 in the serum more consistently than a pure type 1,2,3 vaccine. The duration of colonization, after naso-pharyngeal challenge, was greatly reduced in animals with agglutinin 3.

Local immunity, resulting from previous infection, was even more effective than a good vaccine in preventing subsequent persistent colonization. Marmosets may be useful in studying the possible development of aerosol pertussis vaccine for human use.

For 6 months details of every patient who had his or her urine sent to a laboratory for bacteriological examination and the result of such examination were entered on a computer-card. A total of 15,606 cards were completed with information in code recording the sex and age of a patient, the origin of the request, the presence or absence in the urine of an excess of protein or cells, the culture result and the name of any significant organism isolated together with its sensitivity to various antimicrobial drugs. This information was interrelated in a computer, and in some cases the resulting numerical details were expressed as rates so as to eliminate the effect of uneven sex and age distribution. In this way the occurrence of urinary tract infection and the type of infecting organism in persons of either sex at various ages was examined according to whether the patient was in hospital or general practice. The sensitivity pattern of each type of significant organism isolated was established according to its source. The association between patients of either sex and various ages who had, or did not have, bacteriologically evident infections and the presence in their urine of an inflammatory exudate was investigated. Finally, the capacity of each type of infecting organism to produce such an exudate was estimated.

It was shown that hospital and general practice experience of urinary tract infections differed widely, with regard both to the age and sex distribution of those suffering from it, and to the causative organisms concerned and their sensitivities to antimicrobial drugs. It is suggested that these differences were so great that conclusions drawn from any study of this subject conducted in one of the two areas cannot be applied to the other, and that those derived from a mixture of the two will vary according to the relative sizes of each of the components.

Sera from cynomolgus monkeys from Malaysia, from Indian rhesus monkeys, from various species of monkeys from Africa and from South America have been examined for neutralizing antibody to Tanapox and Yaba viruses. No antibody was found to either virus in the sera of rhesus monkeys or South American monkeys. A certain proportion of sera from cynomolgus monkeys and various species of African monkey showed antibody to one or other of the viruses, but few of the positive sera showed antibody to both. The results would seem to suggest that infection with the two viruses is endemic in African and Malaysian monkeys but does not occur or is very rare in Indian rhesus and New World monkeys.

The cytopathic effect of smallpox and camelpox viruses has been compared in cell cultures derived from human and monkey tissues. The two viruses could easily be distinguished in HeLa, GMK–AH1, BSC–1 and WISH cells, camelpox producing multinucleate giant cells and smallpox producing rounding up of individual cells. In other cells (LLC–MK2, HEK and 2RhK) the differences were not so marked, and in some (VERO, HEL, K and HuTh) no differences were seen.

During the period 1961–71 of 1785 viruses isolated from patients in the general population 503 (28%) were rhinoviruses, 465 (26%) influenza viruses, 248 (14%) enteroviruses, 234 (13%) herpes simplex virus, 132 (7%) parainfluenza viruses, 129 (7%) adenoviruses and 49 (3%) respiratory syncytial virus. Also isolated were 18 strains of mumps virus, 7 coronaviruses and 295 streptococci of groups A, C or G.

Fluctuations were observed in the frequency with which respiratory syncytial virus, parainfluenza virus type 2, and the adenoviruses were isolated over the 10-year period.

Influenza viruses types A and B, parainfluenza viruses types 1 and 2, respiratory syncytial virus, adenoviruses types 3, 4, 6, 7 and 21, and many enteroviruses were all associated with outbreaks.

Infections with influenza viruses A and B and parainfluenza viruses types 1 and 2 came during the winter, whereas those with parainfluenza virus type 3, enteroviruses, and rhinoviruses were more frequently seen in the summer and early autumn.

Sera from domestic cattle, sheep and goats and 11 wild bovid species taken at 41 locations throughout Kenya were screened for antibody to bluetongue virus using the indirect fluorescent antibody method. Positive sera were found at 39 locations and in all the species tested. The distribution of clinical disease was mapped and found to be more restricted than the distribution of antibody. Culicoides were collected in light traps at 55 locations throughout Kenya. The presumptive vector of bluetongue in Kenya, C. pallidipennis, was the most widespread species, found in 38 locations. Both the distribution of antibody and Culicoides have been tabulated by ecological zones to demonstrate that bluetongue virus in its natural state in cattle and wild bovids is far more widespread than clinical bluetongue disease seen in exotic sheep of restricted distribution; and that C. pallidipennis has great ecological range.

After encouraging results of the mass vaccination programme in Iran, in which 5 million children in rural areas were vaccinated with the Japanese Sugiyama strain at its 82nd passage in baby calf kidney, and a progressive decrease in the incidence of measles as well as a reduction of excessive infant mortality, a further attenuated vaccine, produced with the same strain, cloned in Japan, was compared in a field trial with the parent vaccine. The new strain caused fewer reactions than the original strain. Seroconversion with a geometric mean antibody titre of 6·1 was observed in 95% of susceptible children.

Space-time interaction analysis was applied to data from 101 elementary school children who contracted variola minor during an epidemic in Bragança Paulista County, Brazil. One school had two and the other three shifts of students occupying the same classrooms each day. There was no evidence found for excessive numbers of cases to occur among unvaccinated students occupying the same desks or seated near the desks occupied by cases occurring during another shift. Only three cases occurred among the 31 unvaccinated students occupying desks of students with variola from other shifts. Only one of these three subsequent cases occurred at a time interval suggestive of transmission. For the three models tested there was no evidence of space-time interaction between time of onset of the disease and location of desk for pairs of students from different shifts.

Acholeplasma axanthum sp. was isolated from the lung of swine with catarrhal pneumonia. Clinical symptoms of respiratory disease, gross and histological lesions of pneumonia, as well as serological response were produced by intranasal inoculation of ‘miniature pigs’ with the supernatant of lung suspension containing Acholeplasma axanthum and by a 48 hr. broth culture of the strain.

A similar picture of disease was observed in animals held in contact with the animals inoculated with untreated lung suspension. Acholeplasma axanthum was isolated from the nasal cavity, lung and peribronchial lymph nodes 7–41 days after inoculation. No lesions were observed after inoculation of pigs with the supernatant of lung suspension pretreated with oxytetracycline or chloroform, and no successful isolation of Acholeplasma axanthum could be achieved after this treatment.

Two changes were observed in the acid phosphatase of macrophages that had ingested infective TRIC organisms: the proportion of extralysosomal enzyme rose, while the total amount in the cells fell. Both effects were directly related to the number of organisms ingested and increased with time. When macrophages were inoculated with more than 50 organisms per cell, changes were obvious within a few hours; with 2–10 organisms per cell changes were detectable only after 18 hr. or more. Enzyme appeared in the culture medium as the amount in the cells decreased. Ingestion of organisms killed by heat or treated with antibody did not induce such changes. In infected BHK-21 cells, no changes in acid phosphatase were detected at any stage of the developmental cycle of the organism.