Leptospires (Leptospira interrogaus serovar pomona) grown in chemically defined medium were immunogenic when given intradermally in humans if the leptospires were killed with formalin but not if they were boiled. Boiled leptospires were immunogenic for rabbits and hamsters and protected hamsters from challenge infection. On the other hand, boiled leptospires of the biflexa complex, serovar patoc, did retain some immunogenicity in humans, but the antisera did not protect hamsters against challenge with serovar pomona.

Swedish nationals about to travel abroad were immunized against typhoid with a monovalent heat-inactivated vaccine which was administered intra- or subcutaneously. No major differences in serum antibody response were noted in the two groups of vaccinees as determined with direct agglutination and indirect hemagglutination techniques. As the intracutaneous route caused fewer adverse reactions this way of administration seems to be preferable.

Nineteen (22·9%) of 83 sera collected before vaccination from adult volunteers aged 21–64 years were without neutralizing antibody to poliomyeitis at levels of 0·15 i.u./ml for types I and II and 0·1 i.u./ml for type III. Some correlations were found between the history of previous vaccination and the presence of antibody but these were not well defined.

Vaccination with a single dose of trivalent oral polio vaccine elicited fourfold or greater antibody responses to one or more poliomyelitis types in 53 (63·9%) volunteers, the percentage antibody responses being inversely related to the titre of antibody present before vaccination. Types I, II or III poliomyelitis virus were recovered from 76·8 % of faecal samples collected 1 week after vaccination. The percentage recovery progressively declined thereafter until virus was recovered from 10·5 % of samples collected 6 weeks after vaccination.

Type for type, the titres and percentages of antibody responses and virus shedding in faeces were similar following trivalent oral poliomyelitis vaccines whether prepared in monkey kidney or human diploid cell substrates. Some change in reproductive capacity temperature (r.c.t./40) marker was found in faecal isolates from volunteers vaccinated with monkey kidney and human diploid grown vaccines but no change in ‘d’ marker was found.

Serum proteins adsorbed from the culture medium were detected in Mycoplasma bovis antigens, the number and type of proteins depending on the serum used in the medium. The α-globulins cross-reacted with α-globulins from different types of sera but the γ-globulins did not. The removal of non-specific medium antibodies by absorption showed that they affected the gel diffusion and growth precipitation tests, producing cross-reactions between M. bovis and M. bovigenitalium, but that the complement fixation, tube agglutination, and growth inhibition tests were not similarly affected. The presence of serum proteins in the antigens changed their specific reactivity in all the tests. The production of antibodies to serum proteins was increased by the use of an adjuvant, but it appeared that production of specific antibodies to the mycoplasmas was not.

A Biap slit sampler and a Casella Mk 2 slit sampler were studied in an orthopaedic operating theatre. Both showed similar bacterial counts in the range of 74–640 c.f.u. (colony forming units)/m3. During operations, an average count of 220 c.f.u./m3 (range 52–482) was obtained. A close relationship was demonstrated between the number of airborne bacteria and the frequency of traffic through doors.

A microbiological survey of over 400 sanitary dressings is reported: large numbers of bacteria are present, including species indicative of faecal contamination. The need for an effective bactericide in chemical bin exchange systems is thus demonstrated. Screening trials of several candidate formulations have been undertaken: buffered sodium metabisulphite, releasing sulphur dioxide as a vapour-phase bactericide, has now been introduced as an effective bin exchange system.

A total of 882 samples of settled sewage, sewage sludges and final effluents from eight sewage treatment plants were examined for the presence of salmonellas. Of these samples 68% were positive, isolations being made most frequently from settled sewage (85%), raw sludge (87%) and anaerobically digested sludge (96%). Fewer isolations were made from final effluent (24%) and processed sludges (58%). Samples usually contained less than 200 salmonellas/100 ml and arguments are presented that such concentrations should not lead to disease in animals if suitable grazing restrictions are followed.

The influence of pH arid temperature on the efficiency of chlorine inactivation of two unrelated picornaviruses in a typical urban wastewater effluent was examined. Temperature, unlike pH, had relatively little effect on the rate of inactivation. The pH effect was complex and the two viruses differed. The f2 coliphage was more sensitive to chlorine at low pH, but at all values there was a threshold above which additional chlorine resulted in very rapid inactivation. The amount of chlorine required for this was less at low than at high pH, although at pH values above 7 the extent of inactivation was about the same. There was no apparent correlation between pH and rate of inactivation of poliovirus but there was a suggestion that at a pH close to the isoelectric point of the virus it was less sensitive to chlorination.

A large outbreak of streptococcal skin infection occurred late in the summer of 1978 in a factory which undertakes the slaughter, preparation and packing of chickens. In all, 103 episodes of infection occurred in 82 workers from a total factory establishment of 347. The highest incidence of infection was in the packing department where there was an attack rate of 44 %. The routes of introduction of infection into and spread within the factory remain mostly unknown. Following the identification of cases and carriers and the institution of appropriate treatment and control measures the outbreak quickly declined. The responsible organism in the outbreak was Streptococcus pyogenes T-type 3/1 3/B3264, provisional M-type ‘R78/55’. This is the first poultry factory outbreak in England to be reported.

A comparison was made of the heat resistance of Bacillus cereus spores at 95° C. Spores of serotype 1 strains were more resistant than those of the other types tested. However, there was little difference in the growth rate of the various serotypes in boiled rice at 22° C. Most samples of uncooked rice contained multiple serotypes of B. cereus.

These results indicate that the cooking procedure used for the preparation of cooked rice is likely to be selective for certain serotypes, and this is the most likely reason why type 1 is the most common serotype implicated in outbreaks of food poisoning and can be isolated from many routine samples of cooked rice.

Seven different flotation fluids were assessed for their efficiency in recovering Toxocara canis ova from artificially seeded soil samples. Using the most efficient (a saturated solution of magnesium sulphate plus 5 % potassium iodide) 25 g amounts of 234 environmental soil samples were examined for the presence of Toxocara spp. and Toxascaris ova. Twenty-six samples (11·1 %) yielded ova of one or other species. There was no discernible pattern of distribution of positives with relation to the source of the samples. The maximum number of ova recovered in any one sample was 19. All the ova recovered from the environment were considered viable and potentially infective.

Examination of the faeces of 50 babies born at home showed that bottle-fed babies carried significantly more Klebsiella, Proteus and Pseudomonas spp. and antibiotic-resistant Escherichia coli than did breast-fed babies. Bottle-fed babies born in hospital had a less mixed faecal flora than bottle-fed babies born at home. The possibility that bacterial contamination of home-prepared feeds may account for these differences requires investigation.

Hospital food was examined for the presence of Klebsiella species. Salads and cold meat were most frequently contaminated, often containing more than 103 organisms per g. Klebsiella species were also widely distributed in the kitchen environment which was considered, at least in part, to be the source of the organisms in food.

By the use of serological and bacteriocin typing, intestinal carriage of strains ingested in food could be demonstrated.

Topical medicaments used by patients with diseases of the skin were examined for microbial contamination. Ps. aeruginosa was isolated from stock pots of a diluted emulsifying ointment used as a soap substitute in the bath. Cross-con tamination between patients and medicament was subsequently shown to have occurred.

The sex ratios and the emergence patterns of the European rabbit flea bred under animal house conditions were examined. An overall preponderance of female fleas was found. This was due to the greater preponderance of female fleas in the primary emergence, whereas the sex ratios in the secondary emergence were about 1:1.

Biotyping by the scheme of Duguid et al. (1975) of 2010 cultures of Salmonella typhimurium received by the Scottish Salmonella Reference Laboratory in 1974–6, the definitive phage types of which were known, revealed 137 different phage type/biotype groups. Four major epidemic clones, comprising 52 % of the cultures, were recognized: 1/2a, 49/26a, 56/17g and 141/9f. The sources of each of these four groups of strains were primarily bovine (587 cultures) and human (361), suggesting a close association between infections in the two hosts.

Epidermiological evidence showed that most of the outbreaks were caused by cultures of a single phage type/biotype, suggesting that both phage typing and biotyping characters were usually stable in the course of spread of epidemic strains.

Thirty-two of the 63 phage types contained strains of more than one biotype. Cultures from 11 of the phage types were of two or more closely related biotypes and those from 21 others were of unrelated or distantly related biotypes. The combined use of phage typing and biotyping made it possible to detect occasional variations in the phage type or biotype in epidemic clones during their spread, e.g. phage type 49 to 204, 56 to 193, 141 to 193 and biotype 2a to lOa, 9f to 9bf, or 9cf, 26a to 26f.

The baseliiie susceptibility of the lesser bandicoot rat, Bandicota bengalensis, from Rangoon, Burma, to five anticoagulant rodenticides was established with no-choice feeding in the laboratory. The susceptibility of lesser bandicoots to the several poisons (brodifacoum, difenacoum, diphacinone, coumatetralyl, and warfarin) was such that they were offered at a 0·001 % concentration. B. bengalensis was most susceptible to brodifacoum, and in descending order, difenacoum, coumatetralyl, diphacinone and warfarin. In comparison with Rattus norvegicus on warfarin at 0·005 %, B. bengalensis proved more susceptible. Feeding tests at 0·005 % concentration indicated that a 1-day feeding on broclifacoum and difenacoum would result in complete mortality, whereas coumatetralyl and warfarin would require 4 days feeding to a 100 % kill. Brodifacoum and difenacoum are recommended at 0·002–0·005 % bait concentrations and coumatetralyl at 0 001 % concentrations for the control of B. bengalensis in the field in Rangoon. The use of any anticoagulant material in rat control should be alternated with acute toxicants to retard the possible development of anticoagulant resistance.

The continuous administration of food containing 10 mg/kg of avoparcin to groups of 28 chickens in contact with five chickens experimentally infected with a nalidixic acid-resistant (nalr) mutant of a salmonella strain strongly favoured the colonization of their alimentary tracts with salmonella organisms. Bacitracin, 10 mg/kg, either had no effect or only slightly favoured salmonella colonization and sodium arsenilate usually hindered it.

A Most Probable Number (MPN) method involving Differential Reinforced Clostridial Medium followed by streaking on Willis & Hobbs medium was com pared with direct plating of samples on Tryptose-Suiphite-Cycloserine agar with out egg yolk, and two forms of Oleandomycin-Polymyxin-Suiphadiazine-Per fringens agar, one being prepared from a commercial, dehydrated product.

With skin samples taken from chicken carcasses at different stages of processing, the three direct plating media gave similar counts of Cl. perfringens whereas results obtained with the MPN method were consistently lower.

Although counts of Cl. perfringens from various further processed products were usually < 10/g, the three plating media showed similar specificity for this organism.

All media supported good growth of reference strains of Clostridium perfringens but it was founsi that physiologically similar species, including Cl. absonum, Cl. paraperfringens and Cl. perenne also grew uninhibited in these media and produced colonies identical with those of Cl. perfringens, thus indicating the need for confirmatory tests for Cl. perfringens when examining natural samples.