The duration of bacteraemia in guinea-pigs following the subcutaneous inoculation of brucellae can be used as a measure of the virulence of the strains. Strains of low virulence (e.g. Brucella abortus S19) are almost always cleared from the blood stream within a week, whereas virulent strains produce a bacteraemia that regularly persists for 4 weeks and may last very much longer.

All of four strains of Br. melitensis isolated from cow's milk in Great Britain behaved in the same way as the typical and virulent strains of Br. abortus and Br. melitensis tested, regularly producing prolonged bacteraemia. These results do not support the suggestion that the strains of Br. melitensis isolated in this country are of low virulence.

When we consider a probability distribution about how many COVID-19-infected people will transmit the disease, two points become important. First, there could be super-spreaders in these distributions/networks and second, the Pareto principle could be valid in these distributions/networks regarding estimation that 20% of cases were responsible for 80% of local transmission. When we accept that these two points are valid, the distribution of transmission becomes a discrete Pareto distribution, which is a kind of power law. Having such a transmission distribution, then we can simulate COVID-19 networks and find super-spreaders using the centricity measurements in these networks. In this research, in the first we transformed a transmission distribution of statistics and epidemiology into a transmission network of network science and second we try to determine who the super-spreaders are by using this network and eigenvalue centrality measure. We underline that determination of transmission probability distribution is a very important point in the analysis of the epidemic and determining the precautions to be taken.

The serological responses of conventionally reared sheep were compared after vaccination with inactivated parainfluenza 3 (PI3) virus incorporated in three different adjuvants. Inactivated PI3 virus with the double-stranded RNA, BRL 5907 in an oil emulsion was shown to stimulate higher serum antibody titres over the first 5 weeks after vaccination than virus with and without BCG emulsified in oil. The ability of this vaccine to protect specific pathogen-free lambs against challenge with PI3 virus was examined in a second experiment. In this experiment the vaccine stimulated virus neutralizing and haemagglutination inhibiting antibodies in the serum. After intranasal and intratracheal inoculation with PI3 virus at challenge, vaccinated lambs showed no clinical illness and virus isolation was confined, except in one lamb, to the first two days. In contrast, unvaccinated lambs developed respiratory disease and virus was isolated daily for 7 days after challenge.

We investigated faecal samples collected from the rectum of 518 cattle on 371 randomly selected smallholdings in Bangladesh for the presence of sorbitol non-fermenting (SN-F) shiga toxin-producing Escherichia coli (STEC). The SN-F isolates were tested for the presence of rfb O157, stx1, stx2, eae and hlyA genes by polymerase chain reaction (PCR). Seven SN-F isolates lacking these genes were profiled by pulsed-field gel electrophoresis (PFGE) to verify their clonality. SN-F E. coli was identified in 44 [8·5%, 95% confidence interval (CI) 6·4–11·2] samples; of these, 28 (5·4%, 95% CI 3·8–7·7) had shiga toxin-producing strains, although only two carried the rfb O157 gene. Thirteen isolates carried the hlyA gene while 18 harboured the eae gene. Based on PFGE, six pulsotypes were observed among the seven isolates that had no virulence genes. To the best of our knowledge this is the first report on shiga toxin-producing E. coli from direct rectal faecal samples of cattle on smallholdings.

An evaluation of the relationship between predictors and immune response was conducted using data obtained from a clinical trial in 200 Czech healthy adults aged 24–65 years receiving a booster dose of a monovalent tetanus vaccine in 2017. The response was determined from ELISA antibody concentrations of paired sera obtained before and 4 weeks after the immunisation. While all subjects with initial antibody levels <1.2 IU/ml achieved a 100% seroconversion rate (at least a fourfold rise in antibodies), only 8% seroconversion was documented in subjects with initial levels >2.2 IU/ml. The immune response was not affected by sex, age, tetanus vaccine type, concomitant medication, related adverse events or post-vaccination period since there were no significant differences in geometric mean concentrations or seroconversion rates. The seroconversion rate of 56% in smokers was significantly lower than that of 73% achieved in non-smokers. Although the seroconversion rates did not differ between individuals with normal or higher body weight, the adjusted odds ratio (1.3; 95% Cl 1.08–1.60) revealed a positive correlation between seroconversion rate and body mass index (BMI). Although the vaccine-induced response was influenced by pre-vaccination antibody levels, smoking or BMI, the booster immunisation against tetanus produced a sufficient response regardless the predictors.

Difficulties in cultivation outside the body have rendered the exact study of the immunity reactions of the filtrable viruses less easy than in the case of many of the bacteria, and the extension of our knowledge of immunity in these infections is at the present time largely dependent upon observation of the behaviour of human beings when exposed to infection through natural channels. For this reason it is important that the utmost use should be made of such reliable statistics as are available for the study of the epidemiology of such diseases as Encephalitis Lethargica and Acute Anterior Poliomyelitis, with a view to understanding their mode of spread and obtaining some clue as to how they may in the future be controlled.

In an attempt to explain the recent resurgence of homosexually-acquired gonorrhoea in the Lothian region of Scotland the number of infections and pattern of infection (urethral, rectal and pharyngeal) of all gonococcal isolates from homosexual men attending the Department of Genitourinary Medicine at Edinburgh Royal Infirmary between 1985 and 1990 were analysed. Serovar typing data were available from infections acquired between January 1986 and December 1990. A correlation between one serovar, Bacejk/Brpyust, and the overall pattern of gonorrhoea was observed. The number of infections caused by minor serovars also correlated with rates of gonococcal infection. The number of minor serovars isolated, which may represent strains from other geographical locations, is related to the total incidence of gonorrhoea. It is possible that the incidence of Bacejk/Brpyust may be determined by the size of the infected pool of gonorrhoea. The most likely explanation for the recent increase in gonorrhoea is a change in sexual behaviour and/or an influx of strains from other geographical areas.

Sixteen isolates of Escherichia coli were subjected to bacterial restriction endonuclease DNA analysis (BRENDA). Nine of these isolates were from an outbreak of human diarrhoea and produced stable toxin, the remaining seven were non-toxigenic strains from animal and human sources. The isolates from the outbreak produced indistinguishable DNA electrophoretic patterns in spite of their assignment to seven different H serotypes. Their BRENDA patterns were markedly different from the other isolates examined. These results support the epidemiological evidence that a single-strain outbreak had occurred, and they cast doubt on the value of H typing for this particular investigation.

The effects of ozone and ozonized olefins on aerosol survival of bacteriophage øX174 were studied. The ozone concentrations used were between 0 and 110 parts/109, giving decay rates up to 0·03 min−1. The olefins used were trans-2-butene and cyclohexene in concentrations of 500 parts/109 and 2·4 parts/106, respectively. Olefins alone have no effect, whereas in combination with ozone, decay rates of 0·1 min−1 and higher were obtained. The results are discussed in relation to the viricidal effect of open air.

Six strains of Str. pyogenes and four strains of Staph. aureus were found to grow well from large or small inocula in fresh human serum; four strains of E. coli failed to grow from large inocula and were killed when the inocula were small. Ps. pyocyanea, Proteus and Str. viridans sometimes grew and sometimes failed to grow in fresh serum.

In serum which had been treated with trypsin or heated at 56° C. for 1 hr. the Gram-negative bacilli grew readily, and growth was still better in serum which had been heated and then trypsinized. Heating at 56° C. and treatment with proteolytic enzymes were shown to destroy complement and to inactivate the bactericidal activity of fresh serum against a Shigella highly sensitive to the properdin system. It is suggested that these changes might be enough to explain the conversion of serum by proteolytic enzymes into a suitable medium for the growth of coliform bacilli. This change might be brought about by bacterial or leucocytic enzymes. Fibrinolytic serum from a cadaver was found to retain at least a part of its complement and bactericidal activity.

Strains of E. coli, Ps. pyocyanea, Proteus, Staph. aureus and Str. pyogenes were tested for growth in burn slough suspension and blister fluid. In slough suspension all strains grew well, but the Gram-negative bacilli grew rather more vigorously than the Gram-positive cocci. In blister fluid E. coli was killed and other strains grew.

These findings are discussed in relation to wound sepsis.

Lipopolysaceharide from serostrains of Serpulina (Treponema) hyodysenteriae for serogroups A to I was characterized using sodium dodecylsulphate polyacrylamide gel electrophoresis and silver staining. All strains had lipo-polysaccharide components ranging from 10 to 16 kDa that represented lipid A-core polysaccharide regions, and short O-antigen side chain were also recognized in certain immunoblots.

Serological reactions between lipopolysaceharide and antisera against each of these serostrains were examined by Western immunoblotting. There was relatively little antigenic cross-reactivity between LPS from the nine strains, thus confirming their suitability as serostrains.

Using cross-absorbed sera, isolates within serogroups A and E were shown to possess unique epitopes on the core lipopolysaceharide, distinct from serogroup reactivities. These isolates were therefore identified as serovars within the serogroups.

This study confirmed the usefulness of the serotyping scheme for S. hyodysenteriae, in which the bacteria can be placed into serogroups using unabsorbed sera, and into serovars within these using cross-absorbed sera.

Twenty-nine strains of Corynebacterium diphtheriae isolated from throats and 29 strains from skin lesions, the latter mainly from communities of low socio-economic status in tropics and cold climates, have been examined for the property of adherence to human buccal epithelial cells. All throat strains showed adherence. In contrast, strains from skin lesions were predominantly poor adherers. These results indicate that strains of C. diptheriae from throats must now be added to the important group of pathogens which possess the property of adherence to surface epithelial cells of mucous membranes, thus providing an essential first step in the process of colonizing their hosts. The possible role of this phenomenon of adherence to bucco-pharyngeal epithelial cells in the evolution of the host—parasite relationship of C. diphtheriae is discussed.

Since 1987, the number of cases of salmonellosis caused by Salmonella enteritidis has considerably increased in Western Europe. Comparison of endemic animal strains isolated in Belgium from 1976–84 with strains isolated from 1987 on shows that the strains which cause the current epidemic have no features distinguishing them from the previously–isolated strains and that furthermore, they do not constitute a bacterial clone. They belong to 13 different lysotypes and in most cases remain sensitive to antibiotics. Nevertheless, the lysotype 33 which belongs to the phage type 4 [1] has increased significatively. It encompasses 37 % of the animal strains isolated in Belgium from 1987–9, but only 7% of the strains isolated from 1976–84.

It is worth noting that the endemic as well as the epidemic strains contain a virulence plasmid sharing sequence similarities with the FIB and FIIA plasmid replicons and with the VirA and VirB virulence regions of the S. typhimurium virulent plasmid: pIP1350.

This study assessed changes in prevalence and distribution of HIV-1 non-subtype B viruses in Italian and immigrant patients over two decades in a province in Italy. All HIV-positive patients who underwent genotypic resistance testing were selected. Prevalence of non-subtype B viruses in 3-year periods was calculated. All sequences of non-subtype B and those provided by REGA as unassigned were analysed for phylogenetic relationships. In total, 250/1563 (16%) individuals were infected with a non-subtype B virus. Prevalence increased over time, reaching a peak (31·5%) in 2004–2006. In Italian patients, the most frequent subtypes were B (92·5%) and F1 (4%). F1 subtype was also prevalent in patients from South America (13·6%); in patients of African origin, CRF02_AG (54·9%) and G (12·3%) were the most frequent. HIV-1 non-subtype B infections in Italians were mostly found in patients who acquired HIV sexually. A phylogenetic relationship between F subtypes in Italian and representative HIV-1 sequences from Brazil was found. C subtypes in Italians were phylogenetically related to subtypes circulating in Brazil. Inter-subtype recombinants were also found in the latest years. The HIV-1 epidemic in Brescia province evolved to the point where about 1/3 patients recently diagnosed harboured non-B HIV subtypes. The distribution of HIV-1 non-B subtypes in Italian patients resembled that in South American patients and phylogenetic relatedness between some Italian and South American HIV-1 strains was found. The possible epidemiological link between these two populations would have been missed by looking only at risk factors for HIV acquisition declared by patients. The evidence of inter-subtype recombinants points to significant genetic assortment. Overall our results support phylogenetic analysis as a tool for epidemiological investigation in order to guide targeted prevention strategies.

A description is given of a simple method of determining the sensitivity of bacteria to sulphonamides by means of impregnated blotting-paper disks applied to nutrient agar prepared from broth freed from sulphonamide antagonists by incubation with lysed horse red blood cells.

With organisms sensitive to the selected sulphonamide, a zone of inhibition of growth will occur, the diameter of which is related to the concentration of the sulphonamide necessary to inhibit growth. Sensitivity to several sulphonamides can be determined simultaneously.

The impregnated disks can be stored without loss of potency.

A cross-sectional study was carried out in injecting drug users (IDUs) from Greece to assess the seroprevalence of human herpesvirus 8 (HHV-8) and to identify potentially associated risk factors. A total of 288 IDUs were tested for K8.1 antibodies to HHV-8 lytic antigen. Associations between HHV-8 serostatus and potential risk factors were examined using univariate and multivariate logistic regression analysis. Seroprevalence of HHV-8 was 24·3% (95% CI 19·5–29·7), increasing with age from 19·4% in those aged <30 years to 52·9% in those aged ⩾40 years (P for trend=0·003). No statistically significant associations between HHV-8-positive status and gender, educational level, age at first drug injection, needle sharing, number of imprisonments, complications from drug overdose, HIV and HCV were observed. In the multivariate logistic regression analysis, older age (⩾40 vs. <40 years, OR 3·30, 95% CI 1·14–9·56) and report of septicaemia/abscess (yes vs. no, OR 1·80, 95% CI 1·01–3·18) were each independently associated with higher HHV-8 seroprevalence. HHV-8 is highly prevalent in the IDU population in Greece. The independent association between HHV-8 and reported abscess or septicaemia supports the hypothesis that poor hygiene conditions in the setting of drug injection may contribute to HHV-8 transmission.

Streptococcus pyogenes causes a variety of infections because of virulence factors such as capsular hyaluronic acid and M protein. The aim of this study was to determine emm types and capsule phenotype in 110 isolates of S. pyogenes from patients with invasive (sterile sites) and non-invasive (mainly pharyngitis) infections in Chile, and the relationship between both virulence factors. The most abundant types found were emm12, emm1, emm4 and emm28 and their distribution was similar to that seen in Latin America and developed countries, but very different from that in Asia and Pacific Island countries. Ten of 16 emm types identified in pharyngeal isolates were found in sterile-site isolates, and three of nine emm types of sterile-site isolates occurred in pharyngeal isolates; three emm subtypes were novel. The amount of hyaluronic acid was significantly higher in sterile-site isolates but did not differ substantially among emm types. Only three isolates were markedly capsulate and two of them had mutations in the csrR gene that codes for a repressor of capsule synthesis genes. We found a non-random association between emm types and csrR gene alleles suggesting that horizontal gene transfer is not freely occurring in the population.

Tuberculosis (TB) in livestock, caused by Mycobacterium bovis, persists in many countries. In the UK and Ireland, efforts to control TB through culling of badgers (Meles meles), the principal wildlife host, have failed and there is significant interest in vaccination of badgers as an alternative or complementary strategy. Using a simulation model, we show that where TB is self-contained within the badger population and there are no external sources of infection, limited-duration vaccination at a high level of efficacy can reduce or even eradicate TB from the badger population. However, where sources of external infection persist, benefits in TB reduction in badgers can only be achieved by ongoing, annual vaccination. Vaccination is likely to be most effective as part of an integrated disease management strategy incorporating a number of different approaches across the entire host community.

We report the events of an Italian top league soccer club that took place in 1 year (from March 2020 to February 2021) at the time of coronavirus disease 2019 (COVID-19) pandemic. In early March 2020, just before sport competitions were called off due to the national lockdown in Italy, the team, which included 27 players and 26 staff at the time, faced a COVID-19 outbreak, with 16 confirmed and seven probable cases, including three staff members who had to be hospitalised. In May 2020, at the resumption of the training sessions, a high prevalence of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulin G positivity (35/53, 66%) was detected among the members of the group. In the following months, sport activities were organised behind closed doors with stringent risk mitigation procedures in place. As of February 2021, only two new cases of SARS-CoV-2 infection were detected within the group, against more than 3500 nasopharyngeal swabs and 1000 serological tests.

A prospective surveillance system for extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-E) and ESBL-producing Klebsiella spp. (ESBL-K) was implemented in 39 German hospitals with the aim of determining the incidence densities (IDs) of community-onset and hospital-onset cases and of identifying risk factors for high IDs of hospital-onset cases. During 2008, 2081 ESBL-E/K cases were documented. ESBL-E cases (n=1330, 63·9%) were more common than ESBL-K cases (n=751, 36·1%), but a higher proportion of ESBL-K cases (59%) than of ESBL-E cases (39·5%) were hospital-onset cases. The mean IDs were 0·54 (range 0–2·53) per 1000 patient-days for all ESBL-EK cases, 0·29 (range 0–1·81) per 1000 patient-days for community-onset ESBL-EK cases and 0·25 (range 0–1·82) per 1000 patient-days for hospital-onset ESBL-EK cases. Regression analysis showed a linear association between the IDs of community-onset and hospital-onset cases. The wide dissemination of ESBL-E and ESBL-K emphasizes the need for hospital-wide surveillance to guide control measures.