The incubation period during this epidemic was studied using both a spectral analysis-cum-filtering method and analysis of case histories. Using spectral analysis, the modal herd serial interval was estimated to be 8–10 days based on the record of the daily number of outbreaks and an adjusted cattle series. The case histories tended to confirm these estimates but indicated that the serial interval varied considerably between species. The filtering method revealed that the herd serial interval apparently changed during the epidemic. For the first 4 weeks the interval was 8 days, while in the latter stages it was about 2 weeks.

Sera of 1255 individuals from Novi Sad, varying in age from <1 month to 69 years, have been tested for neutralization antibodies to Herpes simplex virus type 1.

The eight newborns tested and 97% of the 507 adults were positive, with titres ranging from 1/4 to 1/256. The titres in newborns were significantly lower than the titres in adults.

After birth the maternal antibodies declined rapidly and 94% of infants at the age of >6 months and <2 years were negative.

After the first year infants in Novi Sad start to acquire herpes-neutralizing antibodies actively, reaching a 50% incidence of positives between the 2nd and 3rd year of age.

Age-specific incidence rates of herpes positives found in Novi Sad have been compared with those reported from Edinburgh, Freiburg i. Br. and Louisiana. Possible influences of several circumstances upon the incidence rate of positives detected by the neutralization test are discussed.

Influenza virus was centrifuged in a KII rotor through a sucrose gradient containing Triton N101, a non-ionic surfactant. The micelles of surfactant formed a band in the gradient. As virus particles passed through the surfactant, the haemagglutinin and neuraminidase proteins were stripped from the surface and remained near the surfactant micelles. The residual virus particles sedimented into a denser region of the gradient and were thus separated from the haemagglutinin and neuraminidase antigens. Fractions containing the surface antigens were pooled and Triton was removed by phase-separation at the cloud point.

Conventional influenza vaccine containing whole virus particles purified on a zonal centrifuge is pyrogenic and can cause systemic and local adverse side effects. An improved vaccine was therefore prepared which contained only the surface antigens of the virus adsorbed to aluminium hydroxide. The antigenicity of this vaccine was compared with conventional vaccine in chickens. Both vaccines induced similar titres of serum haemagglutination-inhibition and neuraminidase inhibition antibody. The dose response curves, however, were different. The surface antigens at vaccine strength without aluminium hydroxide were of negligible pyrogenicity in rabbits.

The Alice strain of live attenuated influenza virus was obtained by selection of a γ inhibitor-resistant strain from a virus recombinant between A/PR/8/34 (H0N1) and A/England/42/72 (H3N2). Its behaviour in vitro and in vivo was studied. Three marker systems were investigated: resistance to serum inhibitors, growth capacity at high temperature and low sensitivity to amantadine hydrochloride. In ferrets the strain was found to be attenuated and immunogenic. Passages in man, animals and eggs have not affected its resistance to γ inhibitors.

The contamination of mycoplasma cell preparations by serum proteins originating from culture medium was studied. A. laidlawii and M. arthritidis cells were grown in the presence of [14C]-aminoacids, and the cells were washed with 0·9% NaCl by threefold centrifugation. Total proteins of the washed cells were analysed by SDS gel electrophoresis. Coomassie-stained electrophoretic patterns were compared with autoradiographs of the same gels. The stained electrophoretic pattern of washed A. laidlawii grown without serum was identical with autoradiographs of the same cells grown without or with serum. That of washed A. laidlawii grown with serum differed from the corresponding autoradiograph by the presence of extra protein bands I, II, III, and IV with molecular weights of over 160,000, 80,000–87,000, 55,000 and 25,000, respectively. The same extra bands were found in stained electrophoretic patterns of washed: (a) A. laidlawii cells grown without serum and mixed with serum in the stationary phase, (b) M. arthritidis cells, as compared with their autoradiographs, (c) serum precipitate. The bands III and IV may be due to the heavy and light chains of γ-globulin, the band II might belong to transferrin or to some component of complement. Acidification of serum to pH 5 brought about 100-fold rise of amount of serum precipitate, the number of bands in the electrophoretic pattern of the precipitate being also increased. Stained electrophoretic patterns of cells purified by twofold centrifugation in step sucrose density gradient (1·20–1·27 g./cm.3 for A. laidlawii, and 1·15–1·25 for M. arthritidis) contained no extra bands and matched completely with their autoradiographs.

It was concluded that contamination of washed mycoplasma cells by serum proteins is mainly due to co-precipitation of aggregated serum proteins together with cells during centrifugation rather than to adsorption of serum proteins on the cell surface.

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.

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.

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.

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.

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.

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.

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.

A bacteriological survey on the distribution and occurrence of coliforms and pathogenic indicators of pollution within the surf-zone and near-shore waters along a section of the Natal coast before the use of submarine outfalls was reported previously. In that report more than half the beaches in the region were found to be of Class IV or III quality. After the submarine outfalls became operational, ten further sampling runs were made. A considerable improvement in the sea-water quality was apparent, most of the beaches being regraded to Class II or I, notably in the bathing areas.

Disposable plastic two-piece suits were compared with conventional cotton suits, gowns, and plastic aprons by nurses in a burns unit. The plastic suits allowed fewer micro-organisms to be dispersed into the environment than the other garments but were less comfortable.

A technique for estimating antibodies to the neuraminidase antigens of influenza A is described.

The antibody response to the haemagglutinin and neuraminidase antigens of influenza A (H3N2) was studied in a boys' public school over the four-year period 1970–4. During this time there were two outbreaks of influenza A and the effect of antibody on the result of natural challenge was investigated. No boy who had homotypic neuraminidase antibody had clinical influenza.

Germ-free piglets were infected intranasally with porcine cytomegalovirus (PCMV) at 1 day (group A) or 3 weeks of age (group B). Viraemia and virus excretion by the nasal, pharyngeal and conjunctival routes was studied up to the time of death or to 12 weeks. Virus was also sought in tissues at death or at slaughter, as well as in a few urine samples.

Viraemia was detected in group A between days 5 and 19 after infection and in group B between days 14 and 16 inclusive. The chief route of virus excretion was the nasal mucosa, followed by the pharynx and conjunctiva; the maximal duration of excretion by these routes was 32, 25 and 14 days for pigs of group A and 9, 7 and 4 days for group B. The quantity of virus was also greater in the former group, of which 3 died of generalized PCMV infection.

A viruria was demonstrated in 2 animals.

Antibody detectable in indirect immunofluorescence (IIF) tests appeared towards the end of the third week, reaching maximal titres at 5 to 7 weeks after infection. The mean peak titre of antibody in group B was lower than in group A.

Corticosteroid treatment at days 56–62 after infection resulted in some recrudescence of virus excretion, accompanied in group B by about a twofold increase in IIF antibody. PCMV was isolated in cultures of lung macrophages from 4 of 7 animals killed at about 12 weeks after inoculation.