Sera from 203 Asian immigrants to the United Kingdom were examined for toxoplasma antibodies. The antibody titres were not significantly different from those found in the indigenous population although there was some indication that a higher domestic animal–human contact in Asia was associated with a higher positivity rate.

An isolation policy in a hospital for skin diseases is reported. Patients carrying penicillin- and tetracycline-resistant organisms were to be isolated in single rooms, though barrier nursing was not practised. The policy failed because the single beds rapidly became blocked with long-stay patients and because even in a single-bed unit patients acquired staphylococci within 3–7 days of admission. Patients with skin diseases often do not feel ‘ill’ and resent isolation.

Salmonella infection on two pig farms and its relation to infection in pigs at slaughter was studied. On the first farm feed ingredients were mixed on the farm, and these included fish meal which was found to be contaminated with salmonellas. The feed was pumped to pigs in liquid form. There was a high salmonella isolation rate at slaughter when the contaminated fish meal was fed hi liquid feed, but it was significantly lower when no fish meal was fed to the pigs examined at slaughter. In some instances the same serotypes were found in fish meal and pig excreta on the farm and in caecal contents of the pigs at slaughter. No serotype was repeatedly isolated from any source and it appeared that the serotypes were not able to establish themselves in the pigs. It is concluded that infection found at slaughter originated on the farm where fish meal introduced and maintained infection. There was an opportunity for salmonellas to have multiplied in the liquid feed for several hours each day.

On a second farm environmental conditions were similar, but feed was given in the form of ready-made pellets and nuts. Salmonellas were not isolated from the feed. At slaughter there was a significantly lower isolation rate than on the first farm.

Strontium chloride enrichment broth was found to be comparable to Rappaport broth for the recovery of a wide range of Salmonella serotypes from man, animals, meat products and effluents. With the exception of cloacal samples from reptiles, both procedures were superior to selenite F.

The performance of strontium chloride M and selenite F enrichment was improved when effluent samples were incubated at 43° C.

Strontium chloride M and Rappaport enrichment were superior to selenite F for the isolation of Arizona species from reptiles.

Strontium chloride B, strontium selenite and Rappaport broths were found suitable for the isolation of multiple Salmonella serotypes from sea water contaminated with abattoir effluents. The strontium chloride B and strontium selenite enrichment media were superior to Rappaport broth when samples were incubated at 43° C.

Modified bismuth sulphite agar was found superior to Salmonella-Shigella agar as a solid subculture medium.

The investigation of a food poisoning outbreak due to Salmonella typhimurium phage type 21 is reported.

The significance of the choice of sampling and isolation techniques in salmon-ellosis in man and animals is discussed.

The incidence of salmonellas in pigs was studied in five farms and a bacon factory.

Persistence and spread of salmonella excretion in pigs in a breeding establishment is described. Salmonella excretor boars and sows were responsible for the spread and perpetuation of infection in the farm. The possibility of spreading salmonella infection between farms through the distribution of excretor pigs was studied. Infection persisted and was related to the initial state of excretion of the pigs while at the farm of origin.

The importance of feeding stuffs as a source of salmonella infection in pigs is discussed. Specially prepared heat treated pellets fed to the pigs prevented the introduction of salmonellas.

The intranasal inoculation of volunteers with living partially attenuated strains of influenza A and B viruses offers a new opportunity to determine the protective effect of serum haemagglutin-inhibiting antibody against a strictly homologous virus, under conditions where the time and dosage of the infective challenge can be controlled, the scoring of proven infections can be more precise and higher rates of infection can be achieved than in most natural epidemics.

In 1032 adult volunteers, whose serum HI antibody titre was determined immediately before virus challenge, there was a consistent inverse quantitative relationship between the HI titre and the likelihood of infection. The PD50 (50 % protective dose) of HI antibody was 1/18–1/36, but an unusual finding was that volunteers with no detectable pre-challenge antibody often seem to be less susceptible to infection than those with pre-challenge antibody in low titre.

In one group of volunteers challenged with an influenza B strain there was no evidence that pre-challenge antibody titres against viral neuraminidase had any significant protective effect against challenge infection.

The air of loose-boxes which had previously held pigs infected with foot-and-mouth disease was sampled for virus after various procedures. Removal of infected pigs led to a 12- to 16-fold reduction in the amount of virus after 5 min. and a 400-fold reduction after 60 min. After heavy spraying (1·2 mm. of water in 5 min.) the amount of virus was reduced 500-fold compared to 30-fold after light spraying (0·20 mm. of water in 5 min.). The partition of infectivity associated with particle size was measured. The partition found after light spraying was similar to that found 5 min. after the pigs had been removed. Heavy spraying brought about a reduction in the infectivity associated with the large particles (> 6 μm.) but had no effect on particles less than 3 μm. A similar partition was found 60 min. after the pigs had been removed. The findings are discussed in relation to the spread of foot-and-mouth disease by the airborne route.

Public Health Laboratory Service Working Group, Niels Skovgaard and B. Brest Nielsen. Journal of Hygiene (1972) 70, 127–40.

On page 132, legend to Table 4 should read Growth of Salmonella from various raw materials sampled from November 1968 to January 1970 in one factory, and which can be used in the manufacture of pig feed.

A. C. Ghosh. Journal of Hygiene (1972) 70, 151–60

On page 154, in footnote to Table 1;

For R = S. bredeney read B = S. bredeney

The antibodies active in the Rose Bengal plate test (RBPT) for bovine brucellosis have been studied. The results of fractionation experiments showed that RBPT activity was associated with fractions containing immunoglobulin of the IgG1 class; other immunoglobulin classes were inactive in this respect although active in other tests. These results were confirmed by inhibition tests with specific antisera and by elution of the antibody from agglutinated RBPT antigen.

The major proportion of the serum complement-fixing activity was also present in the IgG1 fraction and it is suggested that the RBPT and CF reactions are probably mediated by the same antibodies.

Yersinia enterocolitica serotype IX has been found to stimulate the production of vibriocidal antibody against Vibrio cholerae, particularly in Inaba serotype, in experimental rabbits and infected man to a significant degree. This activity could be absorbed by both Inaba and Yersinia antigens from anti-yersinia sera, but Yersinia antigen could not absorb vibriocidal activity from the anti-cholera sera, indicating a unilateral relation.

Vibrio agglutinating antibody, particularly against Ogawa, in anti-yersinia rabbit or human sera was found to be less liable to non-specific stimulation.

V. cholerae, while removing vibriocidal antibody, could not absorb the Yersinia agglutinin from anti-yersinia sera, suggesting that there is a different determinant for these two types of antibody activities.

The non-specific production of vibriocidal antibody by Y. enterocolitica type IX indicates the need for caution in the interpretation of the results of vibriocidal tests where such organisms are prevalent.

Human skin scales which have been shed naturally bear a flora of micro-organisms which is unknown until tested. To replace these scales in a study of the micro-environment of both the human body and of models a method has been devised of making synthetic scales which behave both physically and aerodynamically in a similar way to the natural material. The synthetic materials carry no natural flora and it is possible to include in them test markers of several kinds to assist in identification after dispersion.

A comparison was made of four methods of thawing frozen chickens and an average thaw time for each method was determined.

Fully and partially thawed chickens, inoculated with salmonellas, Clostridium welchii and Slaphylococcus aureus were cooked in a spit-roasting oven at different temperatures for different lengths of time. The chickens were examined freshly cooked and after storage under various conditions.

Spit roasting fully thawed chickens until the outer skin was golden brown was sufficient heat-treatment to kill salmonellas and Staph. aureus but Cl. welchii could survive. Salmonellas could also survive if the chickens were not fully thawed before cooking.

Incorrect storage after cooking was shown to encourage the growth of pathogens.

The incidence of intestinal pathogens in frozen dressed chickens and environmental hazards in spit-roasting establishments were also studied. Of raw chickens examined 35% contained salmonellas (9 serotypes), 63% contained Cl. welchii and 63% Staph. aureus.

A comparison was made between a macrotechnique in tubes and a microtechnique in plastic plates for complement-fixation tests, using strains of three subtypes of the Asia 1 type of foot-and-mouth disease (FMD) virus. The results obtained with these techniques were found to be comparable and delineated the antigenic relationships of the three strains employed. The microtechnique was considered to be both economical with reagents and capable of similar accuracy and reproducibility to that of the standard method in tubes. It was concluded that the antigenic analysis of subtype strains of FMD virus can be conveniently carried out by the use of the microtechnique as described.

During the winter of 1967–8 Sonne dysentery affected neighbouring North London primary schools. This was not simply due to cross-infection between the two schools, for two different, unusual strains of Sh. sonnei were distinguished. One was a novel kanamycin-resistant colicine type 7 strain, and as far as we know this was the first school outbreak due to such a strain to be documented. The other strain was kanamycin-sensitive and of colicine type 0 with a rare specific requirement for aspartic acid. There was some evidence to suggest that the kanamycin-resistant strain was more infective for adults and possibly more pathogenic than the kanamycin-sensitive.

Studies on the transfer of drug resistance and of colicinogeny revealed that the factor determining colicine type 7 was carried on a transmissible plasmid, a new observation. Various drug resistances were also transmissible experimentally, and some were spontaneously unstable. Non-transferable ampicillin-resistance in the colicine type 7 strain and aspartic acid dependence in the colicine type 0 strain enabled all but one of the isolates to be classified into two distinct lines. No common ancestor was found and it was concluded that although occurring together they must have arisen from separate sources.

Variations in mortality attributed to birth injury and atelectasis in the 10 years 1958–67 have been investigated for each county borough of England and Wales. It became evident that diagnostic difficulties in separating these two causes must have been such that for statistical purposes they should be combined in a single rate.

Variables likely to affect the local rates such as the sex ratio of births, and rates of illegitimacy and immaturity as an ill-defined cause of death appeared to affect the mortality levels in certain towns but not sufficiently to account for the wide variations apparent in those levels. It is concluded that local surveys are necessary in the towns with highest rates to uncover differences in numbers of births in hospital, in obstetric techniques and in quality of medical care.

Detailed screening of the patients and staff in a unit specializing in liver disease was carried out over a year to ascertain whether transmission of the serum hepatitis virus was occurring and whether the situation was comparable in any way to that found in a Renal Haemodialysis Unit. Of the 154 patients with liver disease tested on admission, 6% were found to have Australia antigen in the serum and throughout the year there were rarely less than two patients in the ward at any one time with positive serum. No instances of clinical hepatitis were detected in the other patients following their stay in the ward or in their attendant medical, nursing and lay staff. Six staff members were found to have Australia antigen in their serum. In four of these, all nurses, it was present in the first sample tested and so the infection may have been acquired earlier. Temporary elevations in both plasma bilirubin and serum aspartate aminotransferase levels were found in another five staff members whose serum was negative for Australia antigen and who clinically were well. In a further eight and apparently healthy staff members, an isolated but persistent elevation of the plasma bilirubin was noted. In both groups these changes could represent the spread of subclinical infectious hepatitis and it is recommended that in units dealing with ‘liver patients’ not only should considerable care be taken during diagnostic and therapeutic procedures but the medical and nursing staff should be screened at regular intervals.