Cooked chicken was allowed to spoil in a normal kitchen refrigerator (variable temperature) and at a standard4 °C. After 10 days' storage, bacteria were isolated from the chicken. It was found that the numbers oforganisms at variable refrigeration temperature were tenfold higher than those at a uniform 4 °C. In an attempt to find the sources of contamination, swabs were made of different areas of the kitchen. Many of the bacteria isolated from the spoiled chicken, were also isolated from the kitchen environment.

When pure cultures of organisms isolated from spoiled chicken were inoculated into sterile cooked chicken and held at 4 °C, the main spoilage organisms were found to be Pseudomonas putida and Aeromonas hydrophila, which were also isolated from the refrigerator where the chickens were stored in the kitchen.

Aeromonas hydrophila was found in significantly high numbers on plates, cutting knives, chopping boards and cold water taps.

Replication of vaccinia and monkeypox viruses was impeded in the presence of 5-bromodeoxyuridine (BUdR) in RL-33 cells derived from rabbit lung tissue. The different degree of inhibition was found among strains of those viruses, in which it was evident that five strains (CV-1, Lister, IHD, Dairen-I and Ikeda) of vaccinia viruses resulted in more reduced yields of infectious virus than four strains (Sen-19, Orang Utan, Copenhagen and Sierra Leone) of monkeypox viruses. There was also strain variation in BUdR sensitivity within vaccinia viruses but not in the case of monkeypox viruses.

A house to house survey was done from October 1972 to March 1974, covering 52952 individuals of urban population at Lucknow and 50156 individuals of rural population of Unnao district, to find out the incidence of polio-like paralysis in our population. Among 12874 urban children up to 8 years old 8·2/1000 had polio-like paralysis while 4·6/1000 children of the rural population of 13554 children were affected. The incidence was significantly higher in the urban population. In the preschool age group almost 1 out of every 100 children was affected. A higher number of children were affected during 1968–9 and 1971–2, though it did not reach epidemic proportion. The findings show that paralytic polio is a serious problem in our country where poliomyelitis is endemic: this is contrary to the views generally held so far.

The possible sources for the epidemic of bluetongue in Portugal at the beginning of July 1956 were examined. Introduction through authorized importation of domestic or wild ruminants was not feasible, since no cattle, sheep or goats were imported and the wild ruminants were confined to Lisbon Zoo, which was too far from the initial outbreaks. Weather maps were examined to see if the wind could have carried infected Culicoides midges from North Africa. On 21 June 1956 infected midges in Morocco could have been taken offshore by southeast winds and then carried by south winds unusual at that time of year to the south coast of Portugal. The 200–300 km sea crossing would have taken some 10 h and been by day when air temperatures near the sea surface were about 18–20 °C. Bluetongue had not been reported at that time in Morocco, and the possibility of the presence of the virus in Moroccan animals without clinical signs is discussed.

The anticoagulant rodenticide brodifacoum was tested against house mice (Mus musculus L.) infesting farm buildings. In six trials, treatment success was assessed from the results of census baitings conducted before and after treatment. With 0·005% brodifacoum in canary seed/corn oil bait, the control achieved ranged between 92·7% and 100%, mean 98·8%. Two mouse populations were eradicated in 3 to 4 weeks but a few individuals survived each of the other four treatments which lasted 6 weeks. The effectiveness of brodifacoum against mice is compared with that of 0·1% calciferol and 0·025% warfarin in combination. It is concluded that brodifacoum and calciferol/warfarin are equally effective in controlling M. musculus but that brodifacoum treatments need to be conducted fora relatively longer period.

A series of 2092 cultures of Salmonella typhimurium isolated from human, animal and other sources in 57 countries were differentiated into 204 phage types and 19 primary and 147 full biotypes. Different biotypes belonged to the same phage type and different phage types to the same biotype, so the combination of typing methods differentiated strains more finely than either method alone: 574 different ‘phage type/biotypes’ were distinguished in 1937 cultures belonging to the 204 recognized phage types.

The combination of biotyping with phage-typing was valuable in studying the phylogeny and spread of epidemic strains by distinguishing clones of different biotype within the same phage type and by confirming the relationship between cultures isolated from widely dispersed clones and that between cultures isolated before and after a clone had undergone variation in phage type, biotype, colicin type or antibiotic-sensitivity pattern.

A widespread outbreak of infection with S. typhimurium phage type 141 in Scotland comprised independent dissemination of three clones of different biotypes, if, 9f and 31bd. During its epidemic spread in cattle in Britain between 1962 and 1969, another strain underwent variations in phage type (type 44 to type 29), biotype (type 26a to types 26d, 26bd, 26dgi, 26dz and 26i) and antibiotic sensitivity. A group of 275 non-fimbriate, non-inositol-fermenting and non-rhamnose fermenting (FIRN) strains, particularly associated with avian infections and thought to be clonal in origin, contained 27 phage types and 22 full biotypes in the primary biotypes 29–32.

The development of a Klebsiella serotyping method by counter-current immunoelectrophoresis (CIE) is described.

Antisera were prepared against the capsular antigens of 72 type strains and tested for the specificity and strength of their precipitin reactions with antigens from homologous and heterologous serotypes. All antisera produced strong reactions with their homologous antigen: when diluted to titre 63 were highly specific, 3 cross-reacted strongly and 6 weakly with one other antigen. Pools of antisera for screening purposes were constructed on the basis of common cross-reactions: component serotypes of each pool could be detected strongly and specifically.

The technique is simple to perform, fairly rapid, and economical in the use of antisera. Results can be read easily and quickly and the intensity of cross-reactions compared directly. The technique appears to be more specific and is less time consuming than the Quellung method, but further assessment of its efficacy in typing routine clinical cultures is necessary.

During a 7½ year period pneumococci were isolated from body fluids of 124 patients at the Radcliffe Infirmary, Oxford – 72 with pneumonia, 26 with meningitis and 26 with other serious infections. Eighty-one (65%) of the patients were over 50, and 33 (27%) were over 70 years old. Of the 124 pneumococcal strains 104 (84%), including 23 (79%) of those from patients who died, belonged to types included in the vaccines successfully used in South Africa and in Papua New Guinea. The relative frequencies of types in the Oxford series and in a larger British series agreed closely with those found in a recent survey of 3644 bacteraemic pneumococcal infections in 10 American cities. Any polyvalent pneumococcal vaccine licensed for use in the United States is thus likely to be relevant to the situation in Britain.

Sharp reductions in the wild rabbit (Oryctolagus cuniculus (L.)) population in the Mallee are associated with annual myxomatosis epizootics. The extent to which the population reductionsare the direct result of the epizootics varies with time of epizootic occurrence. All grazing animals in the Mallee are under nutritional stress each summer and autumn. When the epizootic occurs during the early summer heavy losses occur in a previously healthy population. Similar losses which occur in the late summer and autumn are the result of a nutritional stress – epizootic complex. The end result in each case is a population reduction of about 80%.

This reduction occurs in a population which is the most resistant to myxomatosis known in Victoria and in association with epizooties caused by field strains of myxoma virus of moderate virulence only.

The earlier summer epizootics are of considerable economic importance because they sharply reduce the pressure on the limited food available for other grazing animals.

The occurrence of antibody to myxoma virus in wild rabbits following epizootics is highest in the semi-arid north-west of Victoria and lowest in temperate southern Victoria. Occurrence ranges up to about 90% in the north-west and to about 70% in the south except on the Western Plains where epizootics are rare and antibody occurrence seldom exceeds 30%.

The establishment of the European rabbit flea may be changing the pattern of occurrence of antibody in the north-west by causing spring outbreaks of myxomatosis. It is suggested that the effects of the replacement of a simple recurring system of epizootic and breeding season several months apart by the occurrence of myxomatosis twice in the same year, once coincident with the breeding season, will be complex. The occurrence of detectable antibody may be less dependent on the infection rate and may be dependent to some extent on the relative timing of spring myxomatosis and the breeding season.

The distribution of antibody to Nairobi sheep disease in sheep and goats in Kenya was found to coincide closely with that of the tick, Rhipicephalus appendiculatus. The proportions of a population in an enzootic area with antibody was similar in the different age groups. No antibody to the virus was found in rodent sera and while some low titres were found in some wild ruminant sera, these were considered to be most likely cross reactions with antibody to related viruses.

Nairobi sheep disease was seen principally upon movement of susceptible animals into the enzootic areas. This occurred most frequently for marketing purposes near the main centres of population. Other outbreaks followed local breakdowns in tick control measures. The disease did not occur in epizootic form during the period under consideration.

Nairobi sheep disease was isolated from pools of Rhipicephalus appendiculatus but not from many pools of other tick species. No virus was isolated from the blood or tissues of a range of wild ruminants and rodents.

The pathogenicity for mice of two mutants of herpes simplex virus (type 1 and type 2), which fail to induce thymidine kinase, were compared with their respective parent strains. The mutants were much less virulent than the parents following either intracerebral or peripheral inoculation. The replication of the virus at the site of inoculation and its progression into the nervous system were studied. Following a very large inoculum in the ear, the type 1 mutant was found to establish a latent infection in the cervical dorsal root ganglia. Mice inoculated intracerebrally with small doses of the mutant viruses were solidly immune to challenge with lethal doses of the parent strain.

Faecal specimens were collected at weekly intervals over the winter months from 141 new-born infants without diarrhoea. Contrary to the findings in other studies, no viruses were detected by electron microscopy or culturein any of these specimens. Over the same period faecal specimens were collected from 84 infants up to four yearsof age admitted to hospital. Rotaviruses or adenoviruses were found in 48% of infants with gastroenteritis. Enteroviruses and other small round virus-like particles were found in infants both with and without gastroenteritis.No viruses or pathogenic bacteria could be found in 34% of specimens from infants with gastroenteritis.

The stools of 37 newborn babies born in hospital were examined for the presence of virus. An extract of every stool passed by each baby was examined in the electron microscope and inoculated into cell cultures. The babies were delivered in four separate maternity units (A–D). All the babies from units A and C (9 babies) were found to be excreting rotavirus though none showed any evidence of diarrhoea. Two of the babies also excreted astrovirus. Subsequently unit A was closed for cleaning and, on reopening with more restrictions on visitors, a further 19 babies were examined. No virus was found in any of their stools, nor was virus observed in the stools of babies from units B and D, where visiting was also more restricted. Visiting restrictions in these units excluded older siblings of the babies. No virus was cultured from any stools in this study.

Ten porcine enteroviruses, 2 porcine adenoviruses and 1 coronavirus were isolated directly from 32 samples ofslurry collected from a pig fattening house. Concentration of the same samples by adsorption with the polyelectrolyte PE-60 yielded 24 porcine enteroviruses and 3 porcine adenoviruses. A porcine enterovirus was isolated, following PE-60 concentration, from 1 of 6 slurry samples from a sow farrowing house. No virus was isolated from 12 samples of slurry from dairy cows nor from 6 slurry samples from a calf-rearing unit. A porcine enterovirus was isolated from soil samples, after concentration with PE-60, collected 1, 2 and 8 days after pig slurry was spread on hay stubble. Two porcine enteroviruses were isolated by membrane filtration from 26 samples of surface run-off from land on which pig slurry was routinely spread, and 2 bovine enteroviruses were isolated from cattle feedlot run-off after adsorption to layers of talc and celite followed by hydroextraction. A porcine enterovirus was also isolated from 1 of 33 samples of surface water collected on farms on which pig slurry was routinely spread on the land, but no virus was isolated from 36 samples of ground water from the same farms. The surface water and ground water samples were concentrated by talc-celite adsorption and hydroextraction.

Roof-collected rainwater is a common water source in subtropical regions and has not been associated with human illness. In Trinidad, the West Indies, a church group, attending a rural camp, developed gastrointestinal illness, caused by Salmonella arechevalata. This rare serotype was isolated from stool specimens of campers, foods eaten at the camp, and a water tap, which was supplied by a storage tank of roof-collected rainwater. The surface of the roof, used as water catchment, was covered with bird faeces. It is postulated that rainwater, falling on the roof, washed off animal excrement which contained S. arechevalata and led to the outbreak of salmonellosis through camper ingestion of contaminated food and water.

We have assessed the effectiveness of flexible-film negative-pressure isolators by physical and biological means. We have found that they afford a high degree of containment and therefore also of safety to hospital staff. We offer some recommendations on the operation of these isolators to ensure the optimum degree of protection.

Studies were made to find evidence of louping-ill virus infection in free-living red grouse and relate this to their breeding success. In areas where ticks were abundant 61 (84%) adult grouse had antibody to the virus compared with 1 (10%) in areas where ticks were relatively scarce. Of 162 chicks tested 25 were shown to be viraemic. Infected chicks were of significantly less weight than comparably aged uninfected birds and the probability that they died was much greater than that of uninfected birds. It is concluded that the relatively poor breeding success in areas of high tick numbers was principally due to infection with louping-ill virus. The susceptibility of the red grouse to infection is discussed.

J. Gallagher and D. M. Horwill, Journal of Hygiene 79, 155–60.

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