Airborne smallpox virus has been recovered in an isolation hospital using an adhesive surface sampling technique in the presence of very low aerosol concentrations. Previous work in this field is reviewed. Successful recovery of airborne virus depends on sampling large volumes of air with a suitable sampler and thorough investigation of the whole sample taken for the presence of viable virus. More information on the characteristics and behaviour of airborne smallpox virus is needed in particular with regard to the future design and siting of smallpox isolation units.

The results are presented of testing untreated producer–retailer herd milk samples for the presence of Brucella abortus during the period 1965–1972 in the North Lancashire region.

There was a steady decline in the incidence of infected herds from 22 % in 1965 to 12% in 1971. A sharp fall to 5% in 1972 suggests that the introduction of the Brucellosis Incentives Scheme and the eradication programme has helped to reduce the practice of selling brucella-infected cattle in the open market which was prevalent in the period 1965 to 1970.

This practice of selling brucella-infected cattle may also be a prime factor in the changing pattern of distribution of the biotypes of B. abortus which was observed during the period 1965 to 1970.

A comparison of the two areas in the region show that the incidence of herd infection was always greater in the area containing flying herds than in the area in which self-contained herds predominated.

The co-ordinates of the dwellings where cases of variola minor (alastrim) occurred during a small epidemic were used in a worked example of contour mapping of disease spread. The contoured variable was the date of onset, relative to an arbitrary base date, of the case introducing the disease into each of twenty-two households. Three contour maps prepared with slightly different computer programmes or dates exhibited similar concentric loops whose centres were close to the first infected household. The average rate of spread of the disease was estimated by regression of the number of days to onset of the first case in the household on the average distance from an arbitrary origin to the relevant contour line. The calculated average rate of spread was 1.22 metres per day. An additional map was contoured using the cumulative number of cases as the contoured variable, relative to the onset of the example epidemic.

Methods of statistical analysis are presented for one or more dilution series experiments where the quantity of interest is the number of virus particles required to infect a cell. These methods are illustrated on several data sets drawn from the literature. Data from seven series, which have been used to support a two-particle model in the literature, are here shown to reject such a model decisively, whereas fifteen other experiments are found to be in excellent agreement with a one-particle model.

Seven smallpox vaccines of known human pathogenicity were tested for their ability to produce pocks on the chick chorioallantois at 39·7° C. Significant differences were found and the more pathogenic strains produced pocks with greater efficiency at 39·7° C. than did strains of average or low pathogenicity.

The properties of 5-p-chlorophenyl silatrane as a rodenticide against Rattus norvegicus and Mus musculus were investigated in the laboratory. The high oral toxicity of the compound was confirmed. When the compound was given to laboratory rats and mice by stomach tube at lethal dosages, signs of poisoning were observed within a minute. When caged wild rats and mice were given a choice between plain and poisoned baits the optimum rodenticidal concentration in the bait was about 0.5% for both species, producing 50% mortality in wild rats and 95% mortality in wild mice. The results are discussed in relation to safety in use and the probable effectiveness of the compound as a rodenticide in field conditions.

Rattus norvegicus infestations on six farmsteads were poisoned with 0.5% 5-p-chlorophenyl silatrane and those on another six with 2.5% zinc phosphide. Both poisons were applied in pinhead oatmeal bait containing also 5% corn oil, after pre-baiting. The result of each treatment was assessed by comparing the take of pre-bait with that of a census bait (wheat) laid after the poisoning.

The zinc phosphide treatments were generally more effective than those done with 5-p-chlorophenyl silatrane, but the latter were somewhat detrimentally affected by cautious baiting on the part of one of the operators.

The results are discussed and it is concluded that although they indicate that 0.5% 5-p-chlorophenyl silatrane may have approached zinc phosphide in effectiveness under the conditions of the trial, it would in most circumstances be significantly less effective and possibly less safe to use than the latter, well-tried poison.

The performance of the rodenticide 5-p-chlorophenyl silatrane at 0.5% in a wholemeal flour/pinhead oatmeal/corn oil bait was compared with that of zinc phosphide at 3% in the same base in poison treatments carried out against urban infestations of the house mouse (Mus musculus L.). Each poison treatment was conducted for 1 day and after 3 days' pre-baiting. The success of the treatments was assessed from census baitings conducted before and after treatment. Treatment success varied considerably with both poisons used but in general 5-p-chlorophenyl silatrane proved to be at least as effective as zinc phosphide, a commonly used acute rodenticide for the control of mice.

Statistical methods are described in detail for the calculating and comparing of cross-infection rates. In addition the use of these rates has been extended to study the influence of age and of different virus types on susceptibility to cross-infection in children's wards.

This paper contains an assessment of the physical performance of a permanently installed down-flow laminar-flow operating room at the London Hospital. This system employs partial walls extending 0.76 m (2.5 ft.) from the ceiling, from which the air is allowed to issue freely downwards at an initial velocity of about 0.4 m./sec. (80 ft./min.).

The usefulness of the partial wall, as compared with a free issuing system, was demonstrated and a comparison made with a fully walled system. It was shown that a fully walled system would be more efficient than a partial-walled system as there was a loss in air velocity of about 20–25% with the partial wall due to the nonconstrained flow of air. This loss would be reflected in an increase in airborne bacterial count and would mean that an increase of 20–25% in the air volume would be required to obtain the same conditions as with the full-walled system. Entrainment of contaminated air was demonstrated but it was concluded that this would be of little consequence in the centre of the clean area, i.e. at the wound site. Sterile instruments, etc., however, on the outside of the clean area, would be more liable to airborne contamination.

Bacterial and dust airborne counts taken during total hip operations gave a very low average figure (0.3 bacteria/ft.3 or 10.5/m.3) from which we conclude that the system was about 30 times cleaner in terms of airborne bacteria than a well ventilated conventional operating-room. We concluded that although the partial-walled system was slightly less efficacious than a normal full-walled system, the freedom of movement and of communication for the operating team could in some circumstances outweigh this disadvantage.

Sound levels were such that normal conversation was possible with little or no awareness of background noise.

Active protection against Pseudomonas aeruginosa could be induced in mice by immunization with either the phenol killed cells or the alcohol precipitated fraction of the slime layer, or the ribosomal vaccine preparation. Passive protection could also be induced by injecting into mice antisera prepared in rabbits against these bacteria. This protection was due to the production of antibodies in reaction to the slime layer; the absorption of these antibodies by the slime caused the loss of protection. The fact that mice were also protected by vaccination with strains other than those used for challenging was attributed to the presence of an antigenically similar slime. Passive protection towards a heterologous strain, even one with an antigenically similar slime layer, was dependent on the dose of the challenging injection.

Despite the existence of a close serological relationship between the entero-viruses Swine Vesicular Disease (SVD) and Coxsackie type B5 (Cx B5), the administration of this Coxsackie virus type to susceptible pigs by various routes failed to produce clinical disease.

Viraemia was not detected after exposure but virus was recovered intermittently from faeces and buccal swabs. A mixed virus population was demonstrated in faecal cultures from some pigs, including Coxsackie virus type B5 and other agents, presumably native pig enteroviruses. The Coxsackie virus persisted in faeces in declining amounts for up to 8 days after primary exposure.

Serum neutralizing antibody showed a transient rise to Coxsackie virus, reaching a peak at 14 days and declining below demonstrable titres by 28 days after exposure. The antibody titres attained were proportional to the dose of virus administered and the degree of neutralization was very similar to both SVD and Cx B5 viruses.

On cross challenge by exposure to SVD virus 28 days after exposure to Cx B5 virus, most animals (5/6) succumbed with typical vesicular lesions, although the serum neutralizing antibody titres showed a characteristically anamnestic response to both viruses.

Two published methods for the maximum likelihood estimation of a common relative potency from a series of parallel-line assays are shown to be equivalent.

Cattle and sheep were housed with infected pigs for 11 days. Small amounts of virus were recovered intermittently from the pharynx, milk and rectal swabs of the cattle, but no evidence of subclinical infection was found. Some indication of virus growth in the sheep was obtained in that large amounts of virus were recovered from the pharyngeal region 4 to 7 days after exposure and six of the eight sheep developed significant titres of neutralizing antibody which were maintained in four animals for at least 6 weeks.

Seven viruses isolated from outbreaks of swine vesicular disease in various countries between 1966 and 1973 were compared in pigs and infant mice. All produced a similar disease and virus excretion pattern in the pig, although the Italy/66 virus was considerably less virulent than the other viruses. The results of cross neutralization tests of convalescent pig sera and the response of 5-day-old mice to intraperitoneal inoculation indicated minor differences between some viruses. The Italy/66, Hong Kong/71 and France/73 viruses differed from each other and also from the Italy/72, England/72, Austria/73 and Poland/73 group of viruses.

Children were immunized with a single batch of pertussis vaccine, either adsorbed on aluminium hydroxide or plain. With a primary course of three injections, adsorbed vaccine produced higher titres of pertussis agglutinins in the serum than did plain vaccine. There was no obvious difference in response between those who received the three doses at intervals of 1–2 months, starting at 3–4 months of age, and those in whom the third dose was delayed until about 6 months after the second, but the number of children in each group was small.

The indirect immunofluorescent technique has been used to study the specific immunoglobulin responses in the sera of 63 non-immune adult women who received either Cendehill rubella vaccine subcutaneously, RA27/3 rubella vaccine subcutaneously, or RA27/3 vaccine intranasally. IgG, IgA and IgM antibodies increased virtually simultaneously, starting about 2 weeks after vaccination. IgG antibody appeared in all subjects and reached maximum titres 4–6 weeks after vaccination. The mean IgG titres elicited by the three different methods of vaccination did not differ significantly. IgA and IgM antibodies reached their highest titres between 21 and 28 days after vaccination and then declined to low or undetectable titres within about 9 weeks. The maximum IgA titres observed after intranasal administration of RA27/3 vaccine were significantly higher than those which occurred when the same vaccine was given subcutaneously, but no significant difference in IgM titres was observed. When unfractionated sera were examined IgA antibody was detected in 57 cases (91%) and IgM in 51 (81%). Fluorescent examination of fractions obtained by centrifugation on sucrose density gradients frequently revealed small amounts of IgA and IgM antibody which could not be detected by staining unfractionated serum, and with the inclusion of these results IgA antibody was detected in 61 cases (97%) and IgM in 59 (94%).

When 39 adults with pre-existing serum antibody were challenged with vaccine a definite IgA response was detected in only one subject and in no case was there any evidence of the appearance of IgM antibody.

Nasal antibody, consisting of IgG or IgA or both, was detected in 17 out of 23 non-immune subjects (74%) who received RA27/3 vaccine, either subcutaneously or intranasally. Titres were much lower than those which occur in the natural disease and there was no evidence that nasal antibody was elicited more readily by intranasal than by subcutaneous vaccination.

A retrospective study of 258 children admitted to Ruchill Hospital, Glasgow, with croup between 1966 and 1972 indicated that the viruses most frequently associated with the syndrome were parainfluenza types 1 and 3 and influenza A. Most cases were admitted in the late autumn and winter months, with a small peak in May and June. This seasonal distribution mirrored the circulation of the main causative agents in the community, parainfluenza 1 being principally associated with the autumn cases, influenza A the winter cases and parainfluenza 3 the summer cases. Two of these ‘croup associated’ viruses showed regular periodicity, parainfluenza 1 occurring biennially in even years and influenza A in most years. The periodicity of parainfluenza 3 is as yet undetermined.

A fatal case of cutaneous anthrax, presenting many unusual features, is reported. No evidence of occupational or domestic exposure to the risk of infection was found.

Outbreaks of epidemic keratoconjunctivitis have occurred among workers in shipyards and other industrial concerns in the West of Scotland in 1956, 1967 and 1971–72. In the most recent episode 220 persons were known to be affected and those mainly involved were shipyard personnel working on the open decks of ships under construction; only a few non-industrial workers were affected. As in previous outbreaks adenovirus type 8 was shown to be the causal organism. It is likely that spread of the virus was probably facilitated in some of the patients by such procedures as first aid measures to remove foreign bodies from the eye. A survey of the family contacts of those affected in 1971–72 revealed that only 2% were secondarily infected. This was probably due to propaganda measures to discourage the use of communal face towels, etc.

Despite close virological surveillance over a period of 6 years of patients attending opthalmic clinics in the West of Scotland, there is as yet no clue to the whereabouts of adenovirus type 8 during interepidemic periods. It is suggested that travellers might be responsible for the introduction of the infection into an area.