Co-cultivation of Legionella pneumophila serogroup I and Acanthamoeba palestinensis in Neff's medium at 35 °C resulted in the intracellular multiplication of the bacteria as demonstrated by electron microscopy and immunofluorescence. In the closed experimental system used, the number of legionellae rose from 107 colony forming units (c. f. u.)/ml initially to a maximum of 1010 c. f. u. /ml on day 5. Legionellae were seen in expelled phagosomes, in some amoebae filling the cytoplasm and in others in which the process of encystment appeared to have commenced.

The detection of Legionella pneumophila in water via guinea-pig intraperitoneal injection has been compared with direct isolation of these organisms on semiselective BCYEα media. Both techniques were of similar sensitivity, detecting as few as 102L. pneumophila in 10 ml of water. However, at this concentration, detection using guinea-pig intraperitoneal injection was via the indirect parameters of antibody production and immunofluorescent microscopy. Isolation of L. pneumophila from guinea-pig tissue for further investigation required > 107 organisms injected and in this respect is relatively much less sensitive than direct isolation on semiselective BCYEα media. Since L. micdadei and L. longbeachae are inhibited by one of the selective supplements used, other supplements and techniques need to be developed in order to avoid possible inhibition of other Legionella species.

Records of 171 cases of bacterial meningitis admitted to Nottingham hospitals from January 1974 to June 1980 were reviewed. The distribution of organisms producing meningitis and the factors influencing mortality in different age groups were assessed. Neisseria meningitidis, Haemophilus infiuenzae and Streptococcus pneumoniae accounted for 69% of all proven cases. The overall mortality was 26% being lowest in patients with meningococcal meningitis (0%) and highest in those with pneumococcal meningitis (53%). The following factors were associated with a poor prognosis: age more than 40 years, or less than 2 months; state of consciousness on admission; high CSF protein concentration; and a positive blood culture. There was no evidence that antibiotic therapy prior to admission affected prognosis. Although many laboratory findings were altered by prior treatment with antibiotics, this did not prevent the establishment of a diagnosis in the individual patient.

This study attempted to find the incidence of scarlet fever in the Oxford region, including the proportion of patients from whom Streptococcus pyogenes could be isolated. General practitioners collected throat swabs from patients with suspected scarlet fever. The swabs were examined for viral and bacterial pathogens. Children admitted to hospital were used as controls. Twenty-five of 105 patients with suspected scarlet fever grew Str. pyogenes; M type 4 was the commonest type. The clinical diagnosis of scarlet fever was not always confirmed by throat culture. The annual incidence of scarlet fever was estimated to be 0·3 cases per 1000 per year.

A Staphylococcus aureus strain grown once in vivo in rabbit pleural cavities was appreciably more resistant to killing by soluble polymorph bactericidins than its broth-grown counterpart. Parallel results were obtained using an adaptation of Solberg's drug-inhibition method of measuring intracellular killing after critical aspects of it had been evaluated and modified. Individual in vivo grown organisms were surrounded by a layer of less dense material which was not capsular in nature but which made the organisms clump together. This surface coating was lost on subculture in vitro, resulting in a reversion to broth-like susceptibility, thus indicating that the surface coating was largely responsible for the enhanced resistance and that it resulted from interactions between staphylococci and components of the rabbits' natural body fluids. Consequently, growth in plasma produced organisms which mimicked in vivo grown organisms in clumping, surface coating and in resistance to killing. The use of plasma-grown staphylococci in further studies of likely resistance mechanisms in vivo is discussed.

Living flies collected from three locations were cultured on selective medium for Campylobacter spp. Campylobacter jejuni was isolated from five (2·4%) of 210 flies examined.

These results suggest that the potential hazard to health from the transmission of campylobacters from animals to human food by flies is small.

During November and December 1981 more than 50 residents in a village in Derbyshire had an acute gastrointestinal illness. One month later a second outbreak occurred affecting another 22 people. Campylobacter jejuni was isolated from 12 patients; no other gastrointestinal pathogens were identified. A casecontrol study showed an association with the consumption of unpasteurized milk from one particular farm. No new cases were identified for 6 months following the application of a Pasteurization Order from 26 January to 23 February 1982.

The production of enterotoxins A, B, C and F by strains of Staphylococcus aureus isolated from various clinical sources and from isolates implicated in food poisoning was investigated.

One hundred and ninety one of the 374 clinical strains (51·1%) were found to be enterotoxigenic; of these, 81 (27·7 %) strains produced enterotoxin A, 57 (15·3 %) strains produced enterotoxin B, 23 (6·2 %) strains produced enterotoxin C, and 64 (17·1 %) strains produced enterotoxin F. These enterotoxigenic strains were most frequently lysed by phages of group III (21·5%) or were not typable (22%).

Eighteen of the 29 strains implicated in food poisoning were enterotoxigenic.

The correlation of antigens and bacteriophage patterns with enterotoxigenicity was determined: enterotoxin A being related to a4 antigen, enterotoxin B to phages of 94/96 complex with c1, o antigens, and enterotoxin F to phages of group I with 2632, k1k2, m antigens.

An outbreak of salmonellosis due to Salmonella saint-paul in two dairy herds was first detected during routine examination of calves soon after calving; infection reached 100% amongst calves and up to 60% amongst milking cows. Excretion by cows continued for over 12 months and by calves for up to 18 months.

The most important factor in controlling the spread of infection was reduction of environmental contamination by removal of carriers, prompt antibiotic treatment of sick calves and reduction in stocking densities.

A natural outbreak of Salmonella saint-paulinfection in two Institute herds was monitored clinically, bactcriologically and immunologically. This paper describes the findings in calves. Morbidity and mortality became apparent 30 days after S. saint-paul was first isolated on routine sampling of neonatal calf faeces. All heifer calves were treated with a tetracycline or ampicillin preparation when they showed clinical signs of disease, while the effects of intradermal vaccination with heat-killed S. saint-paul were assessed in a proportion of the bull calves.

Antibiotic treatment reduced mortality and the number of persistent excretors; vaccination did not affect mortality but, if given during the first week of life, reduced the duration of faecal excretion. Calves which were untreated and unvaccinated, or vaccinated when older than 16 days, excreted S. saint-paul for periods of up to 18 months. Of six ‘recovered’ calves, which had been negative on faecal culture for 5–8 weeks, four yielded S. saint-paul at necropsy. Agglutinating antibody titres were highest in those unvaccinated calves which were persistent excretors.

Stools, known to have contained salmonellas were cultured in three enrichment media on arrival at the laboratory. The three media were laboratory prepared selenite F, laboratory prepared Muller-Kauffmann tetrathionate and commercially obtained Oxoid Muller-Kauffmann tetrathionate (CM343). Where faecal samples were sufficiently large, they were stored at room temperature and re-examined using the same three enrichment broths. Whether fresh or stored stools were investigated, the laboratory prepared media were significantly more efficient than the commercial medium. In a straight comparison of the two laboratory prepared media, no significant difference in efficiency was evident with fresh stool samples. With stored specimens, however, Muller-Kauffmann tetrathionate was significantly better than selenite F. This finding might be relevant in examining samples delayed in the post.

The reliability of colicine typing of Shigella sonnei: as an epidemiological marker has been investigated. Strains from 13 of 110 excretors showed variation in type as determined by typing serial isolates and in 14 of 106 epidemics there was a lack of uniformity in typing results.

The simultaneous presence of two types was found in 11·4 % of patients. In vitro variation was seen after 10 days in 6·8 % of isolates from 44 stools; variation had risen to 9% when isolates were re-examined after one month.

These results suggest that restrictions should be placed on the use of colicine typing as an epidemiologic tool.

The microbial and viral flora in the ventilating ducts of an apartment building was evaluated. Several types of sampler (slit sampler, Andersen sampler, large volume air sampler) were used to evaluate the hourly, weekly and seasonal variation of this flora. The mean bacterial concentration was 17·2 c.f.u./m3 with a maximum level at 07.30 h (41·3 c.f.u./m3) and a minimal concentration in the early afternoon (8 c.f.u./m3). The bacterial concentration observed correlated with the relative humidity in the air-ducts although there were no seasonal differences. The bacteria were mainly gram-positive cocci (73·5%) represented by a large number of Micrococcaceae (47·1 %); gram-positive bacilli accounted for 14·2% of the isolates, gram-negative bacilli 120% and gram-negative cocci 0–3%. The majority of the bacteria-carrying particles were in the respirable range with 80·4 % of them being less than 5 γm. The methods used did not result in the isolation of viruses during the winter sampling period.

The sporicidal activity of two solutions which have been used in the production of ‘sterile’ pre-injection swabs has been investigated. Propylene oxide (3·4 % w/w) and chlorhexidine diacetate (0·6% w/w), both made up in approximately 65% w/w propan-2-ol, were artificially contaminated with spores of Bacillus subtilis var. niger and swabs were impregnated with these; surviving spores were enumerated at various temperatures and times of storage. Chlorhexidine diacetate had no sporicidal activity, whereas the activity of propylene oxide was dependent on temperature. The former should not be considered a sterilant and the latter can only be considered such if a controlled incubation period at an elevated temperature is employed.

On the current conception of the epidemiology of epidemic influenza, as caused by a mechanism of direct spread of the virus from the sick, epidemics must have travelled much more slowly in former times than at present. In contrast, a new hypothesis involving virus latency with seasonal reactivation predicts that in previous centuries influenza epidemics would have spread across the country at much the same speed as in the twentieth century. The study of burial registers in Gloucestershire parishes reported in this paper shows that lethal influenza epidemics at least as early as the sixteenth century can be recognized and dated as at present by the characteristic brief but large excess mortality that they cause. Examples are given showing that the character of the excess mortality caused by lethal influenza has not changed significantly over the centuries, a finding that supports the prediction of the new hypothesis but would not be expected on the current conception of influenzal epidemiology.

In each century, influenzal excess mortalities in Gloucestershire parishes coincided with the date of the relevant influenza epidemic as recorded from widely different parts of Britain, thus further supporting the prediction of the new hypothesis as against current conceptions.

The epidemiology of bovine herpesvirus 1 (BHV 1) infections was studied in 20 dairy herds. Periodic serological surveillance of these herds during three consecutive years (1980–82) was combined with clinical studies. In 19 herds seropositive cows were found indicating previous exposure to BHV 1.

One herd had its first experience with BHV 1 during the study. No indication of virus circulation for at least three years was found in eight herds. In five herds an interval of 2 years without an indication of virus circulation was followed by infections in yearlings, first- and second-calf cows during the third year. One or two cycles of virus circulation in calves and/or yearlings during the 3 year survey were detected in six herds. Most BHV 1 infections passed unnoticed. Signs of respiratory disease inassociation with BHV 1 infection were observed in three herds: young animals were most seriously affected. Clinical manifestations of BHV 1 infections were less pronounced than a few years ago when infections in cows caused frank signs and diagnosis was frequently possible on the basis of a typical clinical picture. BHV 1 was the cause of abortions in the herd that experienced its first infections during thissurvey. A survey of the age-specific BHV 1 neutralizing antibody pattern may be helpful for tracing animals and herds at risk of an outbreak of infectious bovine rhinotracheitis.

Slight modifications of a small, plastic covered greenhouse provided a chamber for the exposure of cattle of all ages to aerosols of foot-and-mouth disease virus. Particle size distributions of aerosols were 76% < 3 μm, 17% 3–6 μm, and 7% > 6 μm immediately after the deVilbis no. 40 nebulizer used was turned off and 90% < 3 μm, 8% 3–6 μm, and 2% > 6 μm 20–30 min later. Pharyngeal virus growth curves and viremia patterns correlated well with the dose of virus to which test cattle were exposed and were similar to those of cattle inoculated intranasally.

Nasal fluid and serum collected from pigs after exposure to live foot and mouth disease (FMD) virus or injection of single oil emulsion (w/o) or double oil emulsion (w/o/w) vaccines were examined for FMD neutralizing activity. After virus exposure the response profiles of serum and nasal mucus were similar to one another. In both, neutralizing activity rose to a peak at one to two weeks after exposure and then subsided slowly. After vaccination with either the w/o or w/o/w preparations a neutralizing response was demonstrable in the serum three to seven days after the first injection, and this was boosted by revaccinations 56 and 117 days later. The neutralizing activity was also detectable in nasal fluid seven days after the first vaccination, but subsequent revaccinations 56 and 117 days later provoked neutralizing titres which were no greater than those observed after the initial vaccination.

Serological evaluations of foot-and-mouth disease type SAT 2 viruses isolated in Kenya between 1979 and 1982 were performed using the two-dimensional microneutralization test. Nine field isolates of epizootiological significance were compared with four vaccine viruses. The results obtained identified Tan 5/68 as the most appropriate reference vaccine virus strain since it had the broadest serological spectrum. Potent Tan 5/68 vaccines would be expected to provide adequate protection against the contemporary SAT 2 field viruses. In the case of K 83/74, which also was shown to have a broad spectrum with viruses isolated in Kenya, the results show that the 1982 isolate from central Kenya was significantly divergent (r < 1·00 at P = 0·01) and warranted tactical revaccination for its control. The study highlighted the fact that strain R1215 which had been isolated from the oesophageal-pharyngeal swabs of asymptomatic carrier cattle had a narrow serological spectrum suggesting that such viruses could be unsuitable as vaccine for the national campaign.

Two connected outbreaks of gastroenteritis in separate hospitals associated with a small round structured virus morphologically indistinguishable from the Norwalk virus are described. The virus was most probably introduced on chicken sandwiches prepared by a member of the kitchen staff who was incubating the disease.