Several methods were used to obtain serologically active materials from cultures of Micropolyspora faeni. From the results of immunodiffusion and immunoelectrophoresis tests on these materials it is suggested that preparations for the laboratory diagnosis of farmer's lung disease (FLD) should contain concentrated culture supernatant (CS) and extracts of mycelium obtained by ultrasonic treatment (MU). Although CS and MU have many serological activities in common they also possess activities unique to each.

Extraction of mycelium with trichloracetic acid, boiling water or methanol yielded a product which gave simple patterns in immunodiffusion tests. The products contained little protein but were rich in carbohydrates, particularly arabinose, galactose and glucosamine. A similar material was obtained from a cell-wall preparation by treatment with lysozyme. Antibodies to the serologically active substances in these materials occurred more frequently in sera of patients with FLD than antibodies to any other M. faeni antigen.

Attempts to obtain serologically active materials from spores were unsuccessful. Moreover antibodies to M. faeni could not be removed from patients' sera by absorption with partially purified spore preparations. It is suggested that the hypersensitivity in FLD arises from exposure to mycelial antigens.

The discriminatory power of multiple-locus variable-number tandem-repeat analysis (MLVA) needs to be evaluated for all Salmonella enterica subspecies enterica serovar Typhimurium (S. Typhimurium) phage types so that the power of this methodology is understood and results can be interpreted correctly during outbreak investigations. We evaluated the ability of MLVA to characterize four definitive phage types (DT) problematic in New Zealand. MLVA discriminated between DT104 isolates although there was very limited variation in the MLVA profiles for isolates with an RDNC phage type (reacts but does not conform to a recognized Typhimurium phage pattern) first observed in New Zealand's Enteric Reference Laboratory in May 2006. Most DT101 isolates had indistinguishable MLVA profiles or profiles that differed at one or two loci. This was also observed in DT160 isolates. MLVA may not identify all common-source outbreaks although it provided valuable data when applied to case isolates from two S. Typhimurium outbreaks.

Porphyromonas gingivalis has been linked to the development and progression of oesophageal squamous cell carcinoma (ESCC), and is considered to be a high-risk factor for ESCC. Currently, the commonly used methods for P. gingivalis detection are culture or DNA extraction-based, which are either time and labour intensive especially for high-throughput applications. We aimed to establish and evaluate a rapid and sensitive direct quantitative polymerase chain reaction (qPCR) protocol for the detection of P. gingivalis without DNA extraction which is suitable for large-scale epidemiological studies. Paired gingival swab samples from 192 subjects undergoing general medical examinations were analysed using two direct and one extraction-based qPCR assays for P. gingivalis. Tris-EDTA buffer-based direct qPCR (TE-direct qPCR), lysis-based direct qPCR (lysis-direct qPCR) and DNA extraction-based qPCR (kit-qPCR) were used, respectively, in 192, 132 and 60 of these samples for quantification of P. gingivalis. The sensitivity and specificity of TE-direct qPCR was 95.24% and 100% compared with lysis-direct qPCR, which was 100% and 97.30% when compared with kit-qPCR; TE-direct qPCR had an almost perfect agreement with lysis-direct qPCR (κ = 0.954) and kit-qPCR (κ = 0.965). Moreover, the assay time used for TE-direct qPCR was 1.5 h. In conclusion, the TE-direct qPCR assay is a simple and efficient method for the quantification of oral P. gingivalis and showed high sensitivity and specificity compared with routine qPCR.

To characterize post-treatment clearance of young forms of Plasmodium falciparum from the blood, three differential equation models, a linear decline, a linear then logarithmic decline, and the Michaelis–Menten (MM) kinetic equation, were fitted to log-transformed serial parasite counts from 30 semi-immune patients with synchronous parasitaemias allocated one of six antimalarial drug regimens. The first two equations were solved analytically. The MM equation was solved numerically using a fifth-order Runge–Kutta method. For each equation, parasite clearance was assumed stochastic and log-transformed parasite counts were assumed to be normally distributed at each time-point. Comparisons between models were by Minimum Akaike Information Criterion Estimate. A constrained MM equation fitted the data at least as well as the other two models in 5 of 6 drug groups and also when pooled data were analysed, providing a single index which could be used in drug efficacy studies in similar situations or as part of more complex models that encompass asynchronous, complicated infections.

During the 2014–2016 Ebola epidemic in West Africa, some communities reacted hostilely to the implementation of quarantine measures. This study's aim was to examine the views of lay people in Guinea on the acceptability of community quarantine. From June to August 2016, 302 adults indicated the acceptability of quarantine in 36 scenarios varying as a function of four factors: the infectious disease's level of contagiousness, its level of lethality, the number of cases in the community and whether persons in quarantine are provided with support services. Five clusters were identified: (1) for 18% of the participants, quarantine is never acceptable; (2) 16% considered, in contrast, that quarantine is always acceptable; (3) for 14%, it depends on the disease's level of contagiousness and lethality; (4) 36% based their judgement not only on the levels of contagiousness and lethality, but also on whether those in quarantine are provided with support services; and (5) 16% had no opinion. Interventions to increase voluntary compliance with community quarantine in Guinea must not be ‘one size fits all’, but must be multifaceted and tailored in design and implementation to match the diversity of people's concerns and needs.

Salmonella spp. is a common zoonotic pathogen, causing gastrointestinal infections in people. Pigs and pig meat are a major source of infection. Although farm biosecurity is believed to be important for controlling Salmonella transmission, robust evidence is lacking on which measures are most effective. This study enrolled 250 pig farms across nine European countries. From each farm, 20 pooled faecal samples (or similar information) were collected and analysed for Salmonella presence. Based on the proportion of positive results, farms were categorised as at higher or lower Salmonella risk, and associations with variables from a comprehensive questionnaire investigated. Multivariable analysis indicated that farms were less likely to be in the higher-risk category if they had ‘<400 sows’; used rodent baits close to pig enclosures; isolated stay-behind (sick) pigs; did not answer that the hygiene lock/ anteroom was easy to clean; did not have a full perimeter fence; did apply downtime of at least 3 days between farrowing batches; and had fully slatted flooring in all fattener buildings. A principal components analysis assessed the sources of variation between farms, and correlation between variables. The study results suggest simple control measures that could be prioritised on European pig farms to control Salmonella.

Although the compartmentalization of poultry industry components has substantial economic implications, and is therefore a concept with huge significance to poultry industries worldwide, the current requirements for compartment status are generic to all OIE member countries. We examined the consequences for potential outbreaks of highly pathogenic avian influenza in the British poultry industry using a metapopulation modelling framework. This framework was used to assess the effectiveness of compartmentalization relative to zoning control, utilizing empirical data to inform the structure of potential epidemiological contacts within the British poultry industry via network links and spatial proximity. Conditions were identified where, despite the efficient isolation of poultry compartments through the removal of network-mediated links, spatially mediated airborne spread enabled spillover of infection with nearby premises making compartmentalization a more ‘risky’ option than zoning control. However, when zoning control did not effectively inhibit long-distance network links, compartmentalization became a relatively more effective control measure than zoning. With better knowledge of likely distance ranges for airborne spread, our approach could help define an appropriate minimum inter-farm distance to provide more specific guidelines for compartmentalization in Great Britain.

During the 1968 epidemic of meningococcal meningitis in Greece, 90% of the meningococci recovered from the spinal fluid of patients belonged to serological group A. In one army barracks and in one Naval Training Centre, where cases occurred, a rate of 52% and 38·9% respectively of healthy nasopharyngeal carriers of group A meningococci was found, despite repeated courses of sulpha-prophylaxis given to all the population of these military establishments shortly before the swabs were taken.

The susceptibility to sulphadiazine of 64 group A meningococci isolated from patients in different regions of the country and from healthy carriers was tested in vitro. It was found that only one strain was sensitive to a concentration of 0·1 mg./100 ml. of sulphadiazine and another to 1 mg./100 ml. For the remaining strains, the minimal inhibitory concentrations of sulphadiazine ranged from 5 mg./100 ml. to more than 20 mg./100 ml.

Thirty-six strains of group B meningococci were isolated from 34 healthy carriers and from two patients. Some of these strains were resistant to sulphadiazine. Only three strains of group C meningococci were isolated from healthy nasopharyngeal carriers in one army barracks.

We wish to express our thanks to Dr R. Faucon, Director of the International Reference Centre for meningococci, for the valuable help he gave to us during our investigation, as well as for the supply of the group-specific agglutinating antimeningococcal sera.

Up to October 2004, dogs and cats imported into Japan were subjected to a quarantine regimen which consisted of vaccination and a 30- to 365-day waiting period in the country of origin and a 14-day quarantine period upon arrival in Japan. This regimen was replaced by a new one, consisting of vaccination, antibody level titration and a 180-day waiting period in the country of origin, in November 2004. To evaluate the effect of this policy change, a quantitative risk assessment was undertaken. The risk of rabies entering Japan through the importation of dogs and cats from the USA under the old – and new – regimens was quantitatively assessed and compared. Under the new regimen, rabies will enter Japan once every 4932 years (90% confidence interval 1812–13 412 years) through the importation of dogs and cats from the USA. Under the old regimen, rabies would enter Japan once every 70 years (39–205 years), 83 years (45–267 years) or 190 years (104–609 years) assuming that the animal departs the country of origin 30 days, 180 days or 365 days after vaccination, respectively. This indicates the policy change would reduce the risk by a factor of 1/25–1/70.

Pertussis is a worldwide acute respiratory disease caused by the bacterium Bordetella pertussis. Despite high vaccine coverage, the bacterium continues to circulate in populations and is still one of the most common vaccine-preventable diseases. In Brazil, pertussis incidence has presented a significant decrease since 1990 but since 2011 a sudden increase in incidence has been observed. Thus, the aim of this study was to perform a molecular epidemiological characterization of B. pertussis strains isolated in the Central-Western region (specifically in Distrito Federal) of Brazil from August 2012 to August 2014. During this period, 92 B. pertussis strains were isolated from the outbreaks. All strains were characterized by serotyping and XbaI pulsed-field gel electrophoresis profiles. From August to December 2012, the most prevalent serotype observed was 1,3 (13/17). During 2013 the prevalence of serotype 1,3 decreased (13/30) and from January 2014 to August 2014 the most prevalent serotype was 1,2 (33/45). Fourteen PFGE profiles were identified. Of these, BP-XbaI0039 prevalence increased from 3/17 in 2012 to 10/30 in 2013, and 35/45 in 2014. These results evidence the selection of a specific genetic profile during this period, suggesting the occurrence of a bacterial genomic profile with high circulation potential.

Mathematical models are constructed to investigate the population dynamics of Verocytotoxin-producing Escherichia coli (VTEC) serogroups O26 and O103 in two different calf cohorts. We compare the epidemiological characteristics of these two serogroups within the same calf cohort as well as the same serogroups between the two calf cohorts. The sources of infection are quantified for both calf cohort studies. VTEC serogroups O26 and O103 mainly differ in the rate at which calves acquire infection from sources other than infected calves, while infected calves typically remain infectious for less than 1 week regardless of the serogroups. Fewer than 20% of VTEC-positive samples are the result of calf-to-calf transmission. PFGE typing data are available for VTEC-positive samples to further subdivide the serogroup data in one of the two calf cohort studies. For serogroup O26 but not O103, there is evidence for unequal environmental exposure to infection with different PFGE types.

The influence of colostrum-derived antibody to louping-ill virus on the course of experimental infection was investigated in lambs. Lambs that had high titres of antibody were refractory to infection. Lambs that had low titres of antibody did not develop a viraemia but either showed an antibody reaction or were sensitized as judged by the immune response, which was typical of an anamnestic response, after rechallenge. Animals that had no antibody 34–20 days before challenge had either no or very slight viraemia, but did develop an antibody response with titres as high as those of control lambs by day 21. Lambs that had been negative for longer periods responded in a similar fashion to controls.

These findings are discussed in relation to the occurrence of disease in lambs kept in louping-ill endemic areas. It is concluded that in such areas infections of lambs are likely to be of minor importance as a cause of mortality and of little epidemiological significance.

This study estimated the seroprevalence and risk factors for acquiring Toxoplasma gondii infection by undergraduate female university students in Jordan. A cross-sectional study from September 2013 to July 2014 analysed 202 blood samples for IgG and IgM antibodies by enzyme-linked immunosorbent assay and a semi-constructed questionnaire was completed by participants to gather information about Toxoplasma infection risk factors. T. gondii IgG antibodies were detected in 66·5% of the females. Only one sample was positive for both IgG and IgM. Using χ2 test, six factors showed significant association with T. gondii infection (P ⩽ 0·01). The multivariate logistic regression model showed that female students living in houses, wet areas, with income >US$750/month and using spring (untreated) water were 47·42, 10·20, 5·00, 3·25 more times at risk to be seropositive for T. gondii, respectively, compared to female students living in apartments, dry areas, with income ≤US$750/month and using treated water, respectively. This study concluded that T. gondii infection in female university students in Jordan is high and most women become infected before marriage; however, congenital toxoplasmosis is still likely to occur in Jordan. Thus, dissemination of protective measures and knowledge by healthcare professionals is essential especially for pregnant women.

Group B Streptococcal isolates (n = 235) from the South of Ireland were characterised by serotyping, antimicrobial susceptibility and determination of the phenotypic and genotypic mechanisms of resistance. Resistance to erythromycin and clindamycin was observed in 21·3% and 20·4% of the total population, respectively. The c-MLSB phenotype was the most common phenotype detected (62%), with ermB being the predominant genetic determinant, present in 84% of resistant isolates. The rare L phenotype was observed in 2·9% (n = 7) of isolates, four of which harboured the lsaC gene responsible for clindamycin resistance. Serotypes Ia, III and II were the most common amongst the entire study population (28·1%, 24·7% and 14%, respectively). Four of the seven L phenotype isolates were serotype III and two of these strains were confirmed as the hypervirulent clone, ST-17 and harboured the hvgA gene. This is the first documented case of the L phenotype in Ireland to date and the study findings emphasise the need for continued monitoring of antibiotic resistance and serotype distribution in GBS isolates from Ireland.

Plasmid profile analysis by agarose gel electrophoresis was carried out on 37 drug-resistant strains of Shigella dysenteriae types 2, 3, 4, 6 and 7. These strains were collected between 1976 and 1985 in Addis Ababa, Ethiopia.

The plasmid profile of S. dysenteriae type 2 strains with R-type CSSuT did not show middle-sized plasmids likely to code for CSSuT resistance. All strains contained a large plasmid of about 120 megadaltons (MDa), and a cryptic plasmid of about 2·2 MDa. The plasmid profiles of S. dysenteriae type 3 with R-types ACSSuT, SSuT and SSu showed a 4·2 MDa SSu-determinant, which was demonstrated in Escherichia coli K12 recipients resulting from triparental crosses. The ACT determinant in S. dysenteriae type 3 with R-type ACSSuT is probably chromosomally mediated. Cryptic plasmids of about 3·0 and 2·2 MDa were found in all S. dysenteriae type 3 isolates. The 4·2 MDa plasmid featured prominently in the plasmid profiles of S. dysenteriae types 4, 6 and 7 with R-types SSuT and SSu. However, this plasmid was not mobilizable by triparental crosses. There was a relative paucity of transferable plasmids in non-Shiga bacillus isolates. However, incompatibility group N plasmids, coding for tetracycline resistance, were detected.

Vulnerability to coronavirus disease (COVID)-19 varies due to differences in interferon gamma (IFNγ) immunity. We investigated whether a key modifiable interferon precursor, interleukin-18, was related to COVID-19, overall and by severity, using Mendelian randomisation. We used four established genome-wide significant genetic predictors of interleukin-18 applied to the most recent genome-wide association study of COVID-19 (June 2021) to obtain Mendelian randomisation inverse variance weighted estimates by severity, i.e. any (cases = 112 612, non-cases = 2 474 079), hospitalised (cases = 24 274, non-cases = 2 061 529) and very severe (cases = 8779, non-cases = 1 001 875) COVID-19. To be comprehensive, we also conducted an exploratory analysis for IFNγ and two related cytokines with less well-established genetic predictors, i.e. interleukin-12 and interleukin-23. Genetically predicted interleukin-18 was associated with lower risk of any COVID-19 (odds ratio (OR) 0.96 per standard deviation, 95% confidence interval (0.94–0.99, P-value 0.004)) and of very severe COVID-19 (OR 0.88, 95% CI 0.78–0.999, P-value 0.048). Sensitivity analysis and a more liberal genetic instrument selection gave largely similar results. Few genome-wide significant genetic predictors were available for IFNγ, interleukin-12 or interleukin-23, and no associations with COVID-19 were evident. Interleukin-18 could be a modifiable target to prevent COVID-19 and should be further explored in an experimental design.

The following investigation into the effect of pasteurisation on the tubercle bacillus was commenced in 1923, in order to ascertain whether the temperatures used in commercial pasteurisation are at all times sufficient to destroy the virulence of the tubercle bacillus in naturally infected tuberculous milk, i.e. milk as secreted by a cow suffering from tuberculosis of the udder.

Knowledge regarding vancomycin-resistant enterococci (VRE) from Middle Eastern countries is scarce. We therefore investigated the antimicrobial resistance profiles and genetic relationships of VRE Enterococcus faecium isolates obtained from patients attending the King Fahad Specialist Hospital, Dammam, during 2006–2007. The predominant VRE comprised 20 vanB, five vanA and one vanA/vanB type isolates, which tended to fall into two genetic clusters that were identifiable phenotypically by their susceptibility to tetracycline. Multi-locus sequence typing of a random selection of isolates showed that they were part of clonal cluster 17, showing the importance of this genotype in nosocomial VRE infections in Saudi Arabia. Further analysis showed that four of the vanA genotype isolates possessed a new type F Tn1546 transposon, associated with IS1216V and IS1251. Finally, E. faecium vanA/B isolates are rarely reported in the clinical setting including in Saudi Arabia.

White pock mutants of cowpox virus produce pocks in the CAM which ‘mimic’ those produced by the parent virus, in macroscopic and microscopic appearance, and in the amount of virus they contain. The proportion of such ‘atypical’ pocks was influenced by the age and source of embryo, incubation temperature and position of the CAM during incubation. Similar results were obtained with white pock mutants isolated from strains of vaccinia, rabbitpox and monkeypox. The appearance of pocks produced by variola, alastrim, ectromelia and vaccinia (Lister) was unaffected by changes in environmental conditions.

I would like to thank Professor K. McCarthy, Professor K. R. Dumbell, Dr C. H. Taylor-Robison and Dr C. R. Madeley for their interest and for kindly providing virus strains, and Miss M. Seyfang for technical assistance.

I would like to thank the Committee on Research, Liverpool University, for a grant towards the cost of the colour plate.

The incidence of Legionnaires' disease has an uneven geographical distribution in Denmark, ranging from 3 to 70 notified cases per million inhabitants per year in different towns. We investigated the prevalence of antibodies to Legionella in the one town with a consistently high incidence (Randers, Aarhus County) and compared it with that of an area of average incidence (Vejle, Vejle County). Blood samples were collected from healthy blood donors in Randers (n=308) and in Vejle (n=400), and analysed for antibodies to Legionella by indirect immunofluorescence antibody test with L. pneumophila, L. micdadei, and L. bozemanii as antigens. Overall 22·9% of the donors had antibody titres of ⩾1:128; indicating that antibodies to Legionella are common in healthy individuals, and reflecting that the bacteria may be widely distributed in the environment. Surprisingly, the study did not reveal a higher prevalence in the hyperendemic area. Thus, the high incidence of notified cases in this particular town may not be attributed to an overall increased exposure of the general population.