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.

Children with urinary infection present at first to their general practitioners; paediatricians to whom they may be referred must assess the validity of the bacteriological diagnosis made at that time. With this in mind an analysis has been made of the laboratory findings in 2204 mid-stream urine specimens from 1586 children between the ages of two and 12 years examined at the request of their general practitioners during the course of one year.

The contamination rate was shown to be low; 8% of the specimens from boys and 19% of those from girls showed definite infection, and the ratio of infections in boys to girls was 1:4. There was a considerable difference in the infecting organisms in the sexes.

Analysis of the reasons for sending the specimens revealed that a high percentage of children who complained of urinary symptoms did not have infection. Of the children complaining of enuresis only there was a significantly greater incidence of infection in girls than in boys.

In the absence of any large studies of urinary infection in domiciliary practice, data from a laboratory which serves many practitioners can contribute to know ledge of the disease.

A computer model was constructed to mimic the 1967–8 foot-and-mouth epizootic in Shropshire and Cheshire, but the daily spatial distribution of outbreaks was randomized. This pattern of outbreaks was then examined to determine what percentage of outbreaks would fulfil an arbitrary set of criteria for milk-lorry-borne disease, or the primary movement of milk. Some 21% of herds visited subsequent to a ‘source farm’ were affected, as were 4% of herds visited after any infected herd. The relevance of these results to the true risk of disease through the primary movement of milk off affected farms is discussed.

From an analysis of the telephone reports in ten FMD Control Centres in the West Midlands, the veterinary officers' reports on each outbreak, the farm patrol reports and the daily number of outbreaks announced on the 17.50 h B.B.C. T.V. News, it would appear that the reporting of suspected outbreaks was indirectly related to the local disease activity. Private veterinary practitioners reported older cases of FMD at the beginning and end of the epidemic than in the middle.

Between 1961 and 1974, 11934 samples of serum were tested by the Sabin- Feldman Dye test for the presence of antibodies to Toxoplasma gondii.

Analysis of high-titred sera suggested that a 6-year cycle of high disease prevalence occurred across Canada. In addition, a decline in the percentage of positive reactions occurred each year in the Fall. The suggestion that this decline was due to dry conditions during the summer months was supported by the observation that differences in the prevalence of toxoplasma infection in ten Canadian cities were related to their average summer rainfall. The significance of these observations in relation to the epidemiology of toxoplasmosis in this country is discussed. The influence of patient age on the prevalence of infection was also investigated; the results obtained suggested that at least 75% of infants with high antibody titres against T. gondii had obtained these antibodies by placental transfer from their mothers.

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.

Enterobacteria are more resistant to nalidixic acid than the majority of other Gram-negative organisms isolated from river water, so allowing their selection on MacConkey agar containing nalidixic acid. Selection is further improved by anaerobic incubation which, with nalidixic acid, virtually eliminates oxidase-positive strains such as Pseudomonas or Aeromonas.

An outbreak of diarrhoea due to Salmonella worthington in five newborn babies, 5 weeks after a similar outbreak in 13 babies for which no cause had been found, occurred in the nursery of a maternity ward. The source of infection was traced to the contaminated rubber tubing of a mechanical suction apparatus. S. worthington was isolated from the rubber tubing and the Y connexion of the suction apparatus from which all the five infected babies had received suction. Reflux of contaminated amniotic fluid into the sterile catheter connected to the apparatus some time before use could have been the means of introducing the infected material to the oropharynx of the newborn babies, and amniotic fluid, acting as a good medium to support the growth of S. worthington, might be responsible for the long-lasting contamination.

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.

A technique was described for the artificial contamination of the upper surface of intravenous infusion container plugs with viable micro-organisms. This technique was employed to assess the adequacy of decontamination of two designs of plug by the use of antiseptic swabbing. Results indicated that the MRO plug surface was more difficult to sterilize than that of the Tra venol plug. The possibility of contamination of the infusion fluid during insertion of the giving-set needle was examined. Results indicated that there was a risk of contamination through the administration-set port of the MRC plug if swabbing was inadequate.

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.

A modified haemagglutination inhibition test for rubella antibodies, using standardized freeze-dried reagents, was developed and compared with haemagglutination inhibition tests using fresh erythrocytes. This comparison was made in collaboration with six European laboratories. A total of 4205 serum samples were tested. The results show that:

(1) Sensitivity and reliability of the modified test are good;

(2) the modified test can be performed in glass tubes as well as in polystyrene microtitration plates.

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.

We have assessed the effect of house-cleaning procedures on changes in airborne dust and bacteria counts and correlated these with respiratory function tests in 14 children with bronchial asthma who were known to have developed attacks at home, and who had positive skin tests to house dust and the house-dust mite.

We have demonstrated that after cleaning procedures a positive and statistically significant correlation exists between the increase in the numbers of small particles, 2 μm. and less in diameter, in the environment, and reduction in mean peak flow. This indicates that particles of this size penetrate the bronchial tree and are the causative factor in the genesis of bronchospasm.

Ninety-eight samples of pig slurry from 54 farms were examined for the presence of salmonellas, porcine enteropathogenic strains of haemolytic Escherichia coli and mycobacteria. Salmonellas were isolated from 12 farms (22 %) and enteropathogenic E. coli from 13 farms (24%). Pathogenic mycobacteria were not isolated.

Salmonellas were isolated from 7 of 16 farms (44%) stocked with ‘minimal disease’ pigs compared with only 5 of 38 farms (13%) stocked with conventionally reared pigs. Conversely enteropathogenic coliforms were isolated from 3 of 16 farms (19%) stocked with ‘minimal disease’ pigs compared with 10 of 38 farms (26%) stocked with conventionally reared pigs.

One thousand two hundred and sixty-nine freeliving, wild mammals, representative of 16 species from estates in Berkshire, Oxfordshire and Surrey, were examined for the presence of salmonellas. Salmonella typhimurium was isolated from 1 and S. dublin from 7 house mice (Mus musculus). There were no isolations from the other species examined. It was concluded that the house-mice infected with S. dublin acquired the organism from experimentally infected cattle.

The wild mammal population does not at present appear to constitute a reservoir for infection of domestic animals.

Haemagglutinating inhibiting antibody (HAI) responses were determined and clinical reactions recorded in 162 adult volunteers who received either 1 or 2 intranasal doses of 107·0 EID 50 WRL 105 strain live influenza vaccine or placebo. After administration of a single dose of vaccine significant antibody responses were obtained in 69 (70%) of 98 volunteers with initial antibody titres of ≤ 1/20. Of the 70 volunteers who received a second dose of vaccine, 62 provided a further post-vaccination sample of serum, and only 3 (4·8 %), who had not responded to the first dose of vaccine, produced a significant antibody response.

Local, upper respiratory and constitutional symptoms were recorded more frequently after the administration of a first dose of vaccine than after placebo or a second dose of vaccine. The symptoms were of a minor nature except in one volunteer who, after the first dose of vaccine, developed influenzal symptoms followed by bronchitis.

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.

The effectiveness of the single-dose poison treatments of farm rat infestations, analysed by comparing the weights of the post-treatment census bait takes in covariance with the weights of the prebait takes, showed that treatments with 2·5% zinc phosphide, 0·3% thallium sulphate or 0·3% gophacide were equally effective and significantly better than were treatments with 1% zinc phosphide or 0·1% thallium sulphate. The methodology and sensitivity of different analyses are also considered.

Selenite F broth and a modified Muller—Kauffmann tetrathionate broth were investigated using sewage-polluted natural water as inocula. The modification of the tetrathionate medium was necessary as commercial alternatives would not allow multiplication of small numbers of salmonellas.

The wide range of molar concentrations in different tetrathionate broths was emphasized.

Selenite F broth was more efficient than Muller—Kauffmann tetrathionate broth, in our hands, with the material tested. Direct inoculation of the enrichment media was used.

Each of the two media examined had a bias towards selection of certain sero types. If possible, both enrichment broths should be used to obtain maximum information.