The faecal-pat prevalence (as estimated by culture) of Campylobacter fetus from cattle and sheep on 19 farms in rural Lancashire was investigated using standard Campylobacter culture techniques and PCR during a 2-year longitudinal study. C. fetus was isolated from 9·48% [95% confidence interval (CI) 8·48–10·48] of cattle faecal pats and 7·29% (95% CI 6·21–9·62) of sheep faecal pats. There was evidence of significant differences in shedding prevalence between geographical regions; cows in geographical zone 3 had an increased risk of shedding C. fetus compared to cows in geographical zones 1 and 2 (OR 6·64, 95% CI 1·67–26·5, P = 0·007), as did cows at pasture (OR 1·66, 95% CI 1·01–2·73, P = 0·046) compared to when housed. Multiple logistic regression modelling demonstrated underlying seasonal periodicity in both species.

The Brucellosis Card test (Brewers' Diagnostic Kits, Hynson, Westcott and Dunning, Inc., Baltimore, Md.) was evaluated in relation to the Brucelloslide test (bioMérieux, France), the microagglutination test (MAT) and the demonstration of brucella-specific IgG, IgM and IgA in an enzyme-linked immunosorbent assay (ELISA). A total of 573 serum specimens was tested. These included sera from patients with acute brucellosis (159), chronic brucellosis (23) and patients who had been diagnosed previously as having had brucella infection (155). Control groups consisted of patients with diseases other than brucellosis (52), others with noninfectious diseases (20), and healthy individuals (164). The Card test detected 100% of the patients with acute and 61% of the patients with chronic brucellosis. The sera from the control groups were all negative. Similar results were obtained with the Brucelloslide test and the MAT. The ELISA test detected brucellaspecific Ig of all classes in the serum of patients with acute brucellosis, and IgG and IgA in the serum of patients with chronic brucellosis. In the latter group, IgM was also detected in 32% of the sera. Twenty-three per cent of sera with titres of 20 by the MAT were positive on the Card test and had ELISA titres for IgM, IgG and IgA of 400. Characterization of the antibodies involved in the Card test showed that sera with IgM ELISA titres of 1600, or an IgM titres of 800 together with IgG and IgA titres ≥ 200 were Card test positive. Higher IgG (≥ 1600) plus IgA (≥ 400) titres were required to produce a positive Card test in the absence of IgM or when the IgM titre was ≤ 200. The Card test has a potential value as a rapid screening test for humans with acute brucellosis and shows similar results to Brucelloslide and MAT tests. ELISA, however, remains the most reliable test for diagnosis of brucellosis especially in patients with chronic and complicated stages of the disease.

An outbreak of Legionnaires' disease occurred in an inner city district in Calgary, Canada. This outbreak spanned a 3-week period in November–December 2012, and a total of eight cases were identified. Four of these cases were critically ill requiring intensive care admission but there was no associated mortality. All cases tested positive for Legionella pneumophila serogroup 1 (LP1) by urinary antigen testing. Five of the eight patients were culture positive for LP1 from respiratory specimens. These isolates were further identified as Knoxville monoclonal subtype and sequence subtype ST222. Whole-genome sequencing revealed that the isolates differed by no more than a single vertically acquired single nucleotide variant, supporting a single point-source outbreak. Hypothesis-based environmental investigation and sampling was conducted; however, a definitive source was not identified. Geomapping of case movements within the affected urban sector revealed a 1·0 km common area of potential exposure, which coincided with multiple active construction sites that used water spray to minimize transient dust. This community point-source Legionnaires' disease outbreak is unique due to its ST222 subtype and occurrence in a relatively dry and cold weather setting in Western Canada. This report suggests community outbreaks of Legionella should not be overlooked as a possibility during late autumn and winter months in the Northern Hemisphere.

An expedition across the Asian part of the Black Sea coast and national parks of Northern Turkey was organized in the summer of 2001 to investigate the presence of Borrelia burgdorferi sensu lato (s.l.), Lyme borreliosis agent, and Anaplasma phagocytophilum, human granulocytic ehrlichiosis agent, in wild mice. A total of 65 Apodemus flavicollis, Apodemus sylvaticus, Microtus epiroticus, Crocidura suaveolens and Mus macedonicus, were captured. Two out of 22 Apodemus sylvaticus specimens were seropositive for B. afzelii by enzyme-linked immunosorbent assay as confirmed by Western blotting, however cultures of skin and bladder samples from all small mammals in Barbour–Stoenner–Kelly's medium-II remained negative for B. burgdorferi s.l. All sera tested were negative for Anaplasma phagocytophilum by indirect immunofluorescent assay. The prevalence of B. burgdorferi s.l. and Anaplasma phagocytophilum is low in wild mice of the Asian part of Northern Turkey.

A containment laboratory unit for research with aerosols of group 2 pathogenic microorganisms is described. The design criteria are based on current UK guidelines, which imply containment at group 3 level during aerosol production, storage, exposure of animals and sampling. Within the aerosol laboratory, primary containment is provided by a Henderson apparatus operating at a negative pressure to the external environment. Flexible film isolators under negative pressure are used for all hazardous microbiological work, e.g. tissue homogenization, and for housing infected laboratory rodents. A novel feature of the animal isolator is the separate ventilation of each cage, which minimizes the risk of cross-infection by aerosol transmission and ensures a similar environment within each cage. The results of an intentional release of a cloud of non-pathogenic microorganisms are presented to show the effectiveness of the containment barriers. Recommendations are given for the safe operation of a containment unit based upon practical experience.

One-hundred and twenty-one isolates of Salmonella enterica serotype Montevideo, representing different biotypes and incidents of infection detected in the UK between 1977 and 1995, were analysed by EcoRI ribotyping, PvuII ribotyping and IS200 fingerprinting. Among the isolates examined, 7 EcoRI ribotypes, 5 PvuII ribotypes and 55 IS200 profile types were recognized and 4 arbitrary groups defined. All 33 isolates of biotype 2d belonged to EcoRI/PvuII ribotype 1/1 and IS200 lineage A and comprised Group I. The other 88 isolates of biotype 10di and its variants were assigned to Groups II–IV. All 27 isolates in Group II were of EcoRI/PvuII ribotype 2/2 and IS200 lineage B. Among the 43 isolates in Group III, 42 of which were of EcoRI/PvuII ribotype 3/3, IS200 analysis identified 38 profiles in lineages C–I. Six EcoRI/PvuII ribotypes and 8 IS200 profiles, mostly in lineages C–E, were recognized among the 18 isolates in Group IV. The combined use of biotyping and ribotyping, and to some extent IS200 profiling, has enhanced our understanding of the clonal structure of serotype Montevideo and provides a basis for further study.

Helicobacter pylori prevalence is elevated in German submarine crews and in United States Navy (USN) surface fleet personnel, but H. pylori prevalence in USN submariners was unknown. The goal of the study was to determine the prevalence of H. pylori in the crews of USN nuclear submarines compared to other military personnel and to the general US population. The presence of H. pylori IgG antibodies was determined in serum samples using a commercial ELISA. Only 47 out of 451 submariners (9·4%) were H. pylori positive, which is similar to that of the US general population with a similar level of education. In contrast, H. pylori prevalence is significantly higher in US Army recruits (26%), USN surface fleet personnel (25%), and German diesel submariners (38%). These data demonstrate that submarine service (and by inference activity requiring isolation and close contact, per se) is not a risk factor for H. pylori infection.

Cases of gastroenteritis were examined to identify if dietary intake prior to an episode and food-handling and storage practices in the home were risk factors for illness. Cases and controls completed a dietary questionnaire after an event or when well, and questionnaires concerning food-handling, storage and general food-hygiene practices. Comparing cases to themselves when well, subjects were more likely to have eaten cold sliced salami, fried rice and foods cooked elsewhere, and to have had a baby in nappies in the house (OR 1·52–6·24, P[les ]0·01). Cases compared to non-cases were more likely to have bought frozen poultry, have eaten foods cooked elsewhere and to have had a baby in nappies in the house (OR 1·44–2·05, P[les ]0·01). Although food-handling and storage practices are considered important, we were unable to detect an association in this study.

The haemagglutinin of influenza virus A 2/Hong Kong/1/68 was shown to be markedly different from that of previously isolated A 2 virus strains. No haemagglutination-inhibiting (HI) antibody to A 2/Hong Kong/1/68 virus was detected in serum specimens collected in 1966 from persons aged 60 years or less. In contrast, HI antibody tests with 270 sera collected in 1968 indicated that 9·6% had demonstrable HI antibody at low titres, and 35·2% of 454 postepidemic (1969) sera had demonstrable HI antibody at relatively high titres. Most sera from persons aged 80 years and more collected in 1968 and 1969 had demonstrable HI anti-body to influenza virus A 2/Hong Kong/1/68. No HI antibody to the Hong Kong virus was detected in pre-epidemic sera from children aged 6 months to 3 years, whereas 32 % of postepidemic sera had HI antibody. The acquisition of HI antibody to A 2/Hong Kong/1/68 was not accompanied by an increase hi the incidence or titres of HI antibody to heterotypic A 2 influenza viruses. For sera from children aged 4–11 years, an increase of HI titre to heterotypic A 2 influenza was found.

The finding that there had been multiple isolations of Palyam serogroup orbiviruses from aborted cattle fetuses in neighbouring Zimbabwe, suggested that there was a need to investigate the possible occurrence of the viruses in South Africa. Unidentified viruses isolated in South Africa, which had been in storage, were examined. Four viruses which had been isolated from Culicoides midges collected at various sites in the years from 1969 to 1977, were identified as three strains of Gweru virus and one of the Nyabira virus (Palyam group serotypes originally described from Zimbabwe) A fifth virus, isolated in 1967 from the blood of a cow with mild fever, was found to be a distinct new member of the Vellore antigenic complex of the Palyam serogroup and was named Apies River virus. Sera from 476 cattle, 150 sheep, 24 goats and 78 humans from 10 farms were tested for neutralizing antibodies to the above three serotypes of virus plus Abadina and Marondera serotypes. Only 1 of 100 cattle sera from two farms in the southern coastal area had antibody, but elsewhere there was a high prevalence of antibody with 254 (53%) of all cattle exhibiting activity for one or more of the five serotypes of virus tested. Only 6 (4%) sheep, 3 (12–5%) goats and 11 (14%) humans had antibody.

Investigations were conducted between 1977 and 1979 to assess the performance of microbiological tests for detecting and identifying residues of therapeutic-type antibacterial substances in meat and offal. Of the 5442 home-produced meat samples examined, 34 (0·63%) showed inhibitory activity in the screening test, which used Bacillus subtilis BGA and Micrococcus luteus as indicator organisms. Identification by electrophoretic and thin-layer chromatography/bio-autography techniques confirmed that only two of the 34 screen failures were due to true antibacterial residues: a pig sample contained a trace of penicillin and a horse sample contained a trace of an incompletely identified substance resembling a tetracycline. Twelve of the other 32 failures in the screen test were due to naturally produced inhibition and were, thus, falsely positive, whilst the remainder were shown to be negative. All of the 85 (8·7%) screen test failures from the 972 imported meat and offal samples tested were falsely positive. Additional samples from certain animals known to have been given antibiotic treatment were tested concurrently to give a more searching indication of screen and identification test efficacy.

The genotype of HCV was determined in 161 chronic HCV-infected patients. The patients were classified into three groups on the basis of the origin of the HCV infection: 50 patients had a history of intravenous drug use (IVDU) but no HIV infection; 41 patients had received blood transfusions, and 70 patients had no known exposure. The distribution of HCV genotypes was associated with the origin of infection and age of patients: genotype 1b was predominant among patients who had received blood transfusions and those without evidence of parenteral exposure (84·6% and 67·7%, respectively), whereas genotype 3a was present in 65·3% of IVDUs. Patients with genotype 1b were older than those with genotypes la or 3a: 50·3 ± 12 vs. 34·1±9·9 and 31 ± 5.4 years, respectively. These findings suggest that the pattern of HCV genotypes in our region is changing and that genotype 1b may be substituted by 3a as the dominant genotype in the future.

1. The effect of blanket-disinfection on aerial contamination of exposed culture plates was studied during a six-month trial in six hospital units, containing a total of 270 beds.

2. Disinfecting blankets after use by each patient did not significantly reduce general bacterial or Staph. aureus counts on exposed culture plates.

3. Disinfected blankets were heavily recontaminated after only a few days' use. A quaternary-ammonium rinse during laundering conferred no self-disinfecting properties on them.

4. Cotton-cellular blankets were more economical and more popular with patients and nurses than were conventional woollen and two other types of cotton blanket.

When applicable, case-crossover studies may be quicker and cheaper to complete than case-control studies. Because time is a major issue in outbreak investigations, we evaluated the interest of this design during a continuous common source food-borne outbreak of salmonellosis for which the vehicle (hamburgers) was also implicated by environmental and laboratory investigations. Seventeen of the 35 cases identified in the outbreak were included in the study according to the availability of menu records with detailed information on food consumed at each meal. Food exposures during a 3-day risk period before onset of illness were compared to those of a control time-interval of the same duration that preceded the risk period by two days. Seventy-seven per cent of the cases (13/17) had consumed hamburgers in the three days preceding onset of illness compared with 29% (5/17) during the control period (P=0·04, odds ratio=5, 95% CI: 1·1–46·9). In this investigation the case-crossover design proved to be a useful and efficient alternative to the case-control approach. However, further evaluation of this design in outbreak investigation is needed.

(i) The theory of amoebic surveys and of related types of pathological surveys is discussed.

(ii) An inequality is derived,

where X is the total number of carriers and X1, X2 are the new carriers found at the first and second examinations.

(iii) Demonstrability is defined and several theoretical distributions of it are considered.

(iv) Demonstrability is shown not to be a constant in the populations considered.

(v) The danger of extrapolation is noted.

(vi) Life-table methods are introduced to treat some well-known published series.

(vii) A criterion for the adequacy of any estimate of the total carrier rate is given. The mean demonstrability of the outstanding carriers after successive examinations must form a decreasing series.

(viii) This criterion usually shows that the method of estimating the carrier rate for Entamoeba histolytica as three times the proportion of positives at a single examination, or as the total number of positives picked up in six examinations, both give too low a carrier rate.

(ix) It is suggested that the investigation of the ‘carrier’ rate may in certain cases be merely a measure of ‘demonstrability’.

(x) Possible future lines of investigation of the problem are noted.

1. Coramine increases the sensitivity of the central nervous system, particularly the centres situated in the medulla.

2. In large doses, Coramine increases the activity of the spinal cord, producing muscular twitchings of the limbs and body which, when severe, take on the character of convulsive movements.

3. There is a wide margin of safety between the therapeutic and lethal doses.

4. Lethal doses produce convulsions and respiratory failure owing to the involvement of the muscles of respiration.

5. Coramine acts as a powerful respiratory stimulant and is able to over-come the depressant effects of morphine on the respiratory centre in the medulla.

6. Small doses of Coramine raise the blood pressure which is due to a peripheral vasoconstriction. This is partly due to a stimulating effect of the drug on the medulla and to some extent to a peripheral action on either the vasoconstrictor nerves or the arterial muscle. Slightly larger but moderate doses sometimes cause a primary relaxation of the arterioles lasting a few seconds, which may cause a small short-lived fall in blood pressure which is never serious in the normal animal. The rise in blood pressure may last ¼–2 hr., according to the dosage employed.

7. Small amounts of Coramine may increase the amplitude and stroke volume of the heart. This effect was never constant. Larger but moderate doses always produced a diminution in cardiac stroke volume with a decrease in cardiac output. The same effect is seen when large doses are employed. This appears to be the cause of the prolonged lowering of the blood pressure following the administration of large doses of Coramine.

8. Coramine dilates the coronary vessels of the myocardium producing an increase in coronary flow.

9. Coramine lowers the pressure in the right auricle of the heart and the pulmonary artery.

10. Coramine has no effect upon intestinal movements except, when large doses are employed, it causes a slight diminution in the amplitude of the movements with a small increase in muscular tone.

The results of this investigation may be summarised as follows:

1. The qx or cage-age mortality curve of a herd increases rapidly to a maximum and thereafter descends to an approximately constant level which is much above the level of the qx for normal mice of ages within the range of real, physiological, age of animals living in the herds.

2. At the latest ages under observation the principal factor of mortality is still the specific factor, so that the advantage produced by selective mortality and active immunisation is brought to a standstill far above the zero line. Exposure in a herd under the conditions of these experiments will not produce an ultimate population fully resistant to the specific factor of infection.

3. It is probable that a large proportion, perhaps a majority, of the members of a herd become infected early in herd life, and gradually increase their degree of immunity because variations of environmental conditions, so far as these are measured by the general herd mortality, become less and less influential on the ultimate mortality of the exposed to risk the later the point in time chosen for measurement.

4. Study of the form of the age-mortality curve is still proceeding; at present we cannot offer an adequate mathematical description of it which takes due account of the biological factors requiring attention.

5. Quite provisionally, we attribute the difference in time of the maxima of the qx curves of Pasteurella and aertrycke epidemics to a difference of average interval between infection and death.

A retrospective cohort study was conducted to quantitate the relationship between neutropenia and rates of clinical bacteraemia among adults with HIV infection receiving medical care at one institution between 1991–5. The primary exposure, absolute neutrophil count (ANC), was summarized as mean ANC within a given week, using a five-level stratification (reference > 1000/μl). ANC stratum-specific rates of bacteraemia were calculated, by organism type. Linear trend tests were performed to assess dose-response relationship between neutropenia and rates of bacteraemia. The cohort included 1645 patients contributing 26785 patients-weeks and 191 episodes of bacteraemia. The unadjusted effect of neutropenia was most evident for bacteraemia due to E. coli (RR 3.4), Klebsiella pneumoniae (RR 16·7), and P. aeruginosa (RR 10.4). For bacteraemia due to any of these three organisms (47 episodes), with reference ANC > 1000/μl, relative rates were: 751–1000/μl, 1·12; 501–750/μl, 2.11; 251–500/μl, 13·58; 0–250/μl, 21·89.

Multilocus enzyme electrophoretic analysis was employed to assess the genetic relatedness of Neisseria gonorrhoeae. Based on the diversity of electromorphs at 9 enzyme loci, 16 electrophoretic types (ETs) were estabilished amongst the 65 isolates. The average number of alleles per enzyme locus was 1·7 and the mean genetic diversity per locus was 0·212. The majority of isolates belonged to either ET1 (32·3%) or ET2 (16·9%). No specific correlation of ETs was seen with serovars as the major types, ETs 1 and 2, were found distributed amongst the various serovars. Major serovars such as Bacjk (IB-1/2) and Bajk (IB-3/6) were each represented by 6 or 8 ETs respectively. Analysis of the genetic relationships of ETs to each other showed some clustering of subgroups that were more closely related than others.

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.