The onset, duration and magnitude of antibody responses to a poxvirus infection were examined. Mice were inoculated intravenously with the WR strain of vaccinia virus and developed pocks on their tails. The number of pocks was related to the size of the inoculum. Virus was detectable in the spleen and infected mice were subsequently immune to intravenous and intra-nasal challenge. Sera of infected animals neutralized both cell-free and cell-associated virus. Antibody against cell-free virus appeared first; maximum titres were reached sooner but were lower than those of antibody neutralizing cell-associated virus. Titres remained high for at least 100 days after infection.

A standard technique for ascertaining the survival characteristics of bacteria after being environmentally stressed is to incubate the bacteria on both selective and non-selective media and count the colonies produced. Based on these colony counts, indexes of injury and persistence of the bacteria are calculated. To compare the stress of two different environments, a persistence ratio is calculated. In this paper, methods of statistical inference concerning these indexes and ratios are presented. These statistical methods use well-known procedures for analysis of binomial data and 2 × 2 table data, and are appropriate when the colony counts follow a Poisson distribution.

Rainbow trout and specimens of pond mud were collected from three fish farms and examined for the presence of Clostridium botulinum. Two of the farms were constructed with concrete channels and one was mud-bottomed.

Cl. botulinum was isolated only from the mud-bottomed farm (24% of muds), and the isolates were all non-proteolytic type B. The implications of the presence of Cl. botulinum spores in the mud of fish farms is discussed.

The preparation of a skin test antigen from Mycobacterium ulcerans by ultrasonic disintegration and filtration is described. The reagent, called Burulin, was tested in Africa in normal school children, and in patients with leprosy, tuberculosis or M. ulcerans disease. Those with tuberculosis or M. ulcerans disease were simultaneously tested with Tuberculin PPD. Burulin was found to be highly specific for patients in the reactive stage of M. ulcerans disease, and there was no cross-reaction in patients with other mycobacterioses. On the other hand, the majority of patients with M. ulcerans disease reacting to Burulin also produce positive reactions to Tuberculin PPD.

The appearance of specific hypersensitivity to virus antigens was examined in mice infected intravenously with vaccinia virus. Both immediate hypersensitivity, transferable by serum, and delayed-type hypersensitivity, transferable only by cells, were apparent 8 days after infection and demonstrable for at least a further 130 days. Production of macrophage migration inhibitory factor by lymphocytes from infected mice was measured directly in terms of inhibition of migration by antigen or indirectly by determining the effect of soluble factors elaborated by the stimulated lymphocytes. The irregular results may have been the resultants of antigen-mediated macrophage stimulation, toxicity and induction of migration inhibitory factor. Transformation of spleen cells – presumably lymphocytes – from infected mice could be induced in vitro by virus antigens for at least 139 days after infection. Virus/lymphocyte interaction appears to be a particularly fruitful area for further study.

The role of viruses and M. pneumoniae in episodes of acute respiratory illness in childhood has been studied in a London general practice. The total isolation rate was 31·7%, but the rate varied from 32·6% in upper respiratory infections to 64·0% in pneumonia. The clinical features associated with infection were influenced not only by the type of agent but also by age and other host factors in the infected children. Rhinoviruses were more commonly isolated than any other agent and were frequently associated with wheezy bronchitis.

The response to passive cutaneous anaphylaxis, dermal hypersensitivity and intravenous provocation tests has been compared in 30, 40, 31 and 24 cattle injected with foot-and-mouth disease vaccine 0, 1, 2 and 3 times respectively, using vaccine components and other substances as test materials. Reaginic antibodies, demonstrated by passive cutaneous anaphylaxis in goats, were directed against BHK 21 cell extracts (20), hydroxypropylmethylcellulose (3) and an unidentified vaccine component (3), and distributed in 0, 5, 19 and 75% of the cattle vaccinated 0, 1, 2 and 3 times. None of the animals showed clinical signs of allergy after vaccination. When BHK 21 cell extract was injected intradermally a significant correlation was noted between the development of large weals and the presence of reagins although the size of the weals was not correlated with the reagin titres. In the case of hydroxypropylmethylcellulose a similar trend was evident. The majority of cattle with large dermal weals possessed reagins but the number of reactions was too small for statistical evaluation. Dermal reactions to sodium penicillin, sodium carboxymethylcellulose, saponin and whole vaccine occurred in both unvaccinated and vaccinated cattle but BHK 21 cell lysate and normal bovine serum provoked weals which increased in frequency according to the number of vaccinations experienced. Intravenous hydroxypropylmethylcellulose elicited a response in all the animals previously injected with certain batches of vaccine but none in those injected with other batches or in unvaccinated controls. BHK 21 cell extract intravenously produced a clinical response in half the tested animals which was uncorrelated with the results of the passive cutaneous anaphylaxis or dermal hypersensitivity tests.

In a study on a Caucasian population in Western Australia the prevalence of antibodies to Epstein–Barr virus (EBV) was 41% in the 9- to 10-year age group, 80% in the 16 to 19-year age group and 92% in young adults. The age-specific annual seroconversion rates indicated two peaks of primary EBV infection in the population studied – one under 5 years of age and the other at adolescence. The geometric mean titre rose with age, from 23 at 5–6 years to 53 at 36–40 years.

It was shown that in 73 families studied there was evidence of probable spread of EBV infection among siblings, particularly between those of the same sex.

Serological study of patients with infectious mononucleosis indicated that 100% of those examined had antibody to EBV and the geometric mean titre was elevated to 210. Rising titres and seroconversion was demonstrated in these patients together with successful establishment of EBV-carrying cell lines from the peripheral blood in two-thirds of the cases.

The addition of dehydrated broth powder to a random selection of bottles from each batch of infusion fluids before sterilization, followed by incubation of the bottles after sterilization, provides a method of sterility testing which possesses many advantages over the traditional method of culturing small samples from bottles after sterilization.

Winter thermal sensations of secondary and primary school-children in Queensland are related to air temperature. Neutrality is estimated by regression analysis of over 6000 assessments and a lower comfort limit is suggested to include 80% of the children. Cold discomfort is seen as the main problem, and comparison is made to an earlier study in England.

The serum antibody titres in 62 cases of acute brucellosis are presented. The antibody persisting after infection and the appearance of non-agglutinating antihuman globulin titres were investigated. The criteria for the serological diagnosis of acute and chronic brucellosis are discussed.

Results are presented of the laboratory examination of faeces specimens from 20,273 patients with acute diarrhoea. These were household index cases seen in general practice in a London borough during the years 1953–68. An annual average of about 2% of households in the area were affected, but there was considerable fluctuation with year and season. Half the patients were children although only one-fifth of the population at risk was under 15 years of age. The greatest incidence of diarrhoea was among children under 5 years old. Male children, but female adults predominated.

Specimens were sent for laboratory diagnosis at the discretion of the general practitioner. The laboratory found some abnormality in nearly a third and there were indications that transmissible infection was involved in about one-fifth of patients. The most common diagnosis was Sonne dysentery (9%) which came in epidemic waves and made its greatest impact among young school children. Microscopy was useful, and giardiasis was diagnosed in 1·4% of index patients. Other parasites were less commonly found. Fatty globules characteristic of an infectious condition we have called ‘fatty diarrhoea’ were frequently observed by microscopy in stools from young children and occasionally from older persons. Blood or pus cells were seen in less than half the shigella and salmonella infections and in a much smaller proportion of the remainder. A test for occult blood performed on specimens from all patients of 40 years or older was positive, in the absence of visible red cells, in a tenth of these cases.

Other studies on the bacteriology of diarrhoea in general practice are referred to and some epidemiological comparisons made. The possible place of unidentified infective agents in the aetiology of undiagnosed diarrhoeas and of ‘fatty diarrhoea’ is discussed.

Outbreaks of salmonellosis caused by serotypes other than S. dublin and S. typhimurium were investigated on 41 farms in north-west England. Of these, 37 (90%) were in dairy cows. There was strong circumstantial evidence that contaminated dairy cake was the source of infection in at least four herds and probably many more. Twenty-six serotypes were encountered with S. newport, the commonest, causing the most severe disease. Most cattle seemed to rid themselves of infection during the following months whether or not they were at pasture, housed in cubicles or in byres. Some cows excreted salmonellas for up to 11 months after the disease outbreak. Associated human salmonellosis was confirmed on 3/41 (7%) of the farms.

A new test, the water agar test, is described that gives a qualitative index of the presence of bacteria that indicate contamination of the cream, poor storage conditions or both of these factors. The method is simple and requires little equipment. The bacteria grow in a film of diluted cream adsorbed on the surface of a non-nutrient base. After incubation at 30 ± 0.5° C. for 18–20 hr., a proteolytic and mucoid colony count is obtained which has the same percentage coefficient of variance as a standard plate count.

An examination of the effect of storage at different temperatures on the types of bacteria present in cream showed that of all the tests done initially, only the water agar test could predict subsequent bacterial growth with any consistency. The multiplication of presumptive coliform organisms occurred even at 3.5° C. Irrespective of the colony count, the methylene blue reduction time was not shorter than 7½ hr. unless the bacteria were in the logarithmic phase of growth when sampled.

A survey was made of the bacterial flora of 188 retail samples of double cream of 15 different brands. The age of the samples varied from freshly separated cream to cream that had been kept in the shop for a day longer than that recommended for sale. The water agar test was compared with the colony count, the presumptive coliform test, a confirmatory coliform count in violet red-bile agar, a lipolytic colony count, a staphylococcal count and the methylene blue reduction test.

The conglutinating complement fixation test was compared with the haemolytic complement fixation test for the detection of brucella antibodies in human sera. Conglutinating-complement-fixation antibodies were detectable during the early stages of acute brucellosis and persisted for approximately 1 year after the infection.

A serological analysis of mycelial antigens of Thermoactinomyces vulgaris in immunodiffusion with human sera revealed five individual antigens. Three antigens were proteins, sensitive to pronase and soluble in phenol. Two were cationic polysaccharides, sensitive to sodium periodate, and containing glucosamine and muramic acid.

Latex coated with mycelial antigens was compared with precipitin tests in detecting antibodies to T. vulgaris; the number of positive results detected by each test differed slightly, and a combination of the two tests detected the highest number. Counterimmunoelectrophoresis (CIE) was shown to be a very sensitive method for detecting precipitins, but not for their measurement. A prospective evaluation of immunodiffusion, latex agglutination and CIE as potential serodiagnostic techniques for farmer's lung disease is suggested.

The use of a fluid-enrichment technique increased by 10–16% the recovery rate of Brucella abortus from milks of herds positive to a milk ring test. Three solid media for direct cultural techniques were also tested on the same milks. Combinations of these techniques produced a recovery rate of ca. 88% from MRT-positive-herd milks using a mixture of the centrifuged deposit and cream layer as the inoculum as against a recovery rate of ca. 75% using the MRT cream layer as inoculum. B. abortus biotypes 1–5 and 9 were isolated and growth of all the biotypes was supported by all media used.

A total of 50 duplicate Moore swabs were placed for 2 days, on five different dates, in 9–12 points of the Athens sewage disposal system.

Three methods of enrichment were used for the isolation of salmonellas. In the first method, one half of the duplicate swabs was incubated in Muller–Kauffmann's tetrathionate broth at 43° C. for one day. For the second method, a secondary enrichment was carried out in Rappaport's broth, made from the Muller–Kauffmann's broth and for the third method, the other half of the duplicate swab was cultured in Heart Infusion broth at 43° C. for 16–18 hr. after which a secondary enrichment was made in Rappaport's medium.

By use of these 3 enrichment procedures, 96% of the swabs were found to be positive for salmonellas. A total of 178 strains were isolated (an average of 3·7 strains per positive swab), belonging to 53 different serotypes (an average of 1·1 different serotypes per positive swab).

With the simple enrichment in Muller–Kauffmann's broth, only 72% of the swabs were found positive, and 68 strains of salmonellas belonging to 30 different serotypes were isolated. The secondary enrichment in Rappaport's medium made from the Muller–Kauffmann's broth produced 88% positive samples, and yielded 82 strains belonging to 34 different serotypes. Finally, with the secondary enrichment in Rappaport's broth made from the heart infusion broth, 92% of the swabs were positive and yielded 67 strains of salmonellas belonging to 27 different serotypes.

Although the last procedure yielded the greatest number of positive swabs, the method involving secondary enrichment in Rappaport's broth made from Muller–Kauffmann's broth led to the isolation of the greatest number of strains and different serotypes, while the other two procedures were approximately equal in this respect.

Of the 178 strains isolated, 110 were recovered only by the procedures involving secondary enrichment in Rappaport's broth. The most frequently isolated serotypes were Salmonella senftenberg (33 strains), S.typhimurium including var-copenhagen (18 strains), S.poona (11 strains), S.montevideo (10 strains), etc. The following 23 serotypes were isolated for the first time in Greece: S. adelaide, S. alachua, S. allerton, S. binza, S. bobo, S. butantan, S. gnesta, S. goelzau, S. haelsingborg, S. havana, S. hofit, S. ibadan, S. indiana, S. irumu, S. jodhpur, S. nienstedten, S. panama, S. pomona, S. poona, S. reading, S. schwarzengrund, S. stockholm, S. tournai. Moreover, a new serotype, S. athinai was described.

Two FMDV strains which had been previously differentiated by complement-fixation were compared by guinea-pig protection test, kinetic neutralization and micro-neutralization tests. It was found that these tests, which have not been previously applied by the methods described, were all capable of FMDV strain differentiation. Similar differences were found by all methods, which suggests that comparisons made by cross-CF, cross-neutralization or cross-protection involve measurement of the same antigen/antibody interactions.

Abattoir drain swabs, bovine faeces and a few other veterinary samples were examined for the presence of Salmonella dublin. Three selective agar media and four enrichment broths were investigated. The two most efficient plating media were deoxycholate citrate agar and brilliant green MacConkey agar. Wilson and Blair's bismuth sulphite agar (de Loureiro's modification) was least successful. Selenite F broth, whether incubated at 37 or 43° C., was better than the other enrichment broths used which contained a triphenyl methane dye as one of the selective ingredients.