In July 2008, office workers in Dublin complained of influenza-like illness preceding and interspersing two cases of notified Legionnaires' disease. Legionella pneumophila serogroup 1 was identified in both cooling towers supplying the office. A retrospective cohort study was undertaken to investigate possible Pontiac fever (PF). Forty-seven employees (23%) met the clinical case definition for PF but confirmatory testing was negative. Exposure to the smoking area situated beside the cooling towers was associated with an increased risk of PF (RR 2·4, 95% CI 1·5–3·8). The diagnosis of PF should be considered when many persons exposed to a possible reservoir of Legionella spp. present with flu-like symptoms. More sensitive microbiological tests would allow better confirmation and more comprehensive reporting of PF. Early detection is vital to prevent potentially severe illness and outbreaks of PF or Legionnaires' disease.

Hepatitis G virus or GB virus C (GBV-C) is a human virus of the Flaviviridae family that is structurally and epidemiologically closest to hepatitis C virus, but replicates primarily in lymphocytes. Co-infection with GBV-C has been reported to confer beneficial outcomes in some HIV-positive patients. Up to now, however, studies on GBV-C infection in the central nervous system (CNS) of HIV-infected patient have rarely been reported. Herein, we report on a 32-year-old HIV-1-infected patient with cerebral toxoplasmosis and fungal encephalitis. GBV-C viral loads were detected in CSF by quantitative real-time reverse transcription polymerase chain reaction (RT–PCR), and the results showed that GBV-C viral load was 6·5 log copies/ml. We amplified and sequenced the E2 and 5′-untranslated regions from the purified viral RNA from CSF by RT–PCR. Both sequences belong to genotype 3 and there were some minor nucleotide divergence among the E2 sequences from the CSF of the patient. These data suggest that GBV-C may be able to penetrate the blood–brain barrier and colonize the CNS of HIV-infected patients. However, the exact mechanisms and potential effect of the infected GBV-C in CNS on HIV-associated neuropathy needs to be further explored.

The ability of a new, surface-antigen-adsorbed influenza virus vaccine to induce serum antibody in hamsters, and to protect these hamsters against subsequent homologous virus challenge, is reported. In addition, similar studies in hamsters have also been carried out using the surface antigen material prior to adsorption to the aluminium hydroxide carrier. The new, adsorbed vaccine is at least as effective as inactivated saline influenza virus vaccine in inducing serum antibody and protection in hamsters; the unadsorbed surface antigen material, however, did not confer protection to hamsters challenged subsequently with homologous virus.

Rickets is produced in rats by feeding exclusively with cereals and yellow peas. Whereas feeding with polished rice results in typical rickets, feeding with rice-starch alone will only produce osteoporosis. This difference is not attributable to nitrogen starvation.

If oatmeal is extracted with hydrochloric acid and the extract is given in addition to the starch, the animals develop rickets. The rickets-producing factor of oatmeal must therefore be ascribed to some toxic substance. Evidence is given to show that this substance can pass through parchment-paper and that it can be precipitated with alcohol. Rickets produced by feeding with cereals can be prevented by the administration of calcium-salts, whereas phosphates have no such effect.

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.

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.

A 1-year prospective study of nosocomial bacteraemia was performed at Hvidovre Hospital with special reference to frequency, focus of infection and prognosis. All patients were examined clinically in order to confirm the bacteraemia. In total, 98 hospital-acquired bacteraemias were observed, giving an incidence rate of 0·28%. Bacteraemia due to Escherichia coli, Staphylococcus aureus and Staphylococcus epidermidis predominated. The overall mortality was 38%; 65% of the patients with S. aureus bacteraemia died, 25% due to the bacteraemia. The most common types of infection were urinary tract infections and intravenous catheter infections. Fifty-five of the bacteraemias were caused by foreign bodies, mostly urinary catheters and intravenous catheters, and in 14 cases the focus was unknown. The patient population was severely ill patients. We conclude that nosocomial bacteraemia occurs specially in severely ill patients often preceded by indwelling urinary or intravenous catheters. The patients seldom die due to the bacteraemia, but they die with concomitant bacteraemia.

Outbreak of Mycobacterium tuberculosis infections associated with acupuncture has not been reported. Thirteen patients with a painful swollen lump were referred to our hospital. The index patient received acupuncture and paraspinal muscular injection at a local acupuncture clinic in April 2011 and was diagnosed with M. tuberculosis 1 month later. From May 2011 to August 2011, 12 more patients with a swollen lump on the nuchal region or in the lower back or the buttocks region were referred to our hospital. Tuberculin skin test (TST), T-SPOT.TB, acid-fast stain, M. tuberculosis culture, chest radiograph, and lump magnetic resonance imaging (MRI) were performed and the patients were diagnosed with tuberculous abscess of the lump. All 13 patients received intramuscular injection at the paraspinal muscle by two acupuncturists at a local clinic and reported a swollen lump at the injection site. The needles and syringes were reused after autoclave sterilization. The TST was positive in all patients. Twelve patients had positive acid-fast stains. Mycobacterial cultures of abscess specimens were positive in all 13 patients. T-SPOT.TB tests were positive in all patients who underwent the test. The lesions and biopsies were subjected to polymerase chain reaction (PCR) and gene sequencing by the Disease Control Center of Zhejiang Province, China and the causative agent was identified as M. tuberculosis, Beijing type. In conclusion, physicians should consider the possibility of mycobacterial infections, apart from other bacterial agents, in patients with a swollen paraspinal lump following intramuscular injection.

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.

Estimating the case fatality ratio (CFR) for COVID-19 is an important aspect of public health. However, calculating CFR accurately is problematic early in a novel disease outbreak, due to uncertainties regarding the time course of disease and difficulties in diagnosis and reporting of cases. In this work, we present a simple method for calculating the CFR using only public case and death data over time by exploiting the correspondence between the time distributions of cases and deaths. The time-shifted distribution (TSD) analysis generates two parameters of interest: the delay time between reporting of cases and deaths and the CFR. These parameters converge reliably over time once the exponential growth phase has finished. Analysis is performed for early COVID-19 outbreaks in many countries, and we discuss corrections to CFR values using excess-death and seroprevalence data to estimate the infection fatality ratio (IFR). While CFR values range from 0.2% to 20% in different countries, estimates for IFR are mostly around 0.5–0.8% for countries that experienced moderate outbreaks and 1–3% for severe outbreaks. The simplicity and transparency of TSD analysis enhance its usefulness in characterizing a new disease as well as the state of the health and reporting systems.

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 infection by mycobacteria, other than tubercle bacilli (MOTT) is increasing in the United Kingdom, Europe and the United States. These diseases increase morbidity and are an increasing public health concern. However, the epidemiology of disease due to these species is not well characterized. We used space–time clustering approaches and Generalized Linear Modelling to investigate the potential predictors of disease in cases of infection by organisms of the Mycobacterium avium complex (MAC) and M. malmoense recorded in the north of England during 2000–2005. There was significant spatial and temporal clustering in juvenile cases of infection by MAC but not for cases of infection in adults by either species. There were no significant predictors of infection by M. malmoense or juvenile cases of M. avium. Incidence of disease caused by M. avium in adults was significantly related to health deprivation and weakly related to rainfall. We consider possible reasons for the difference in epidemiology in infection by M. avium in adults and juveniles.

The epidemiology of influenza A in Japan was studied during 1979–91 and viruses isolated from reinfections during 1983–91 were analysed, Of 2963 influenza viruses isolated during this period, 922 and 1006 were influenza A(H1N1) and A(H3N2) viruses respectively; the others were influenza B viruses. Influenza A(H1N1) and A(H3N2) caused 5 and 6 epidemics respectively, most accompanied by antigenic drift. Seventeen reinfections with H1N1 and 17 with H3N2 were detected during our study. The primary and reinfection strains isolated from 7 H1N1 and 10 H3N2 cases were studied by haemagglutination-inhibition, and amino acid and nucleotide sequences of the HA1 region of the haemagglutinin. Most of the primary and reinfection strains were antigenically and genetically similar to the epidemic viruses circulating at that time. However, in 4 out of 10 cases of reinfection with influenza H3N2 virus, reinfection strains were genetically different from the epidemic viruses.

The saliva-based H. pylori test, HeliSAL™, is insufficiently accurate for use in the clinical setting. However, its ease of use and non-invasiveness make it attractive for population-based studies of the epidemiology of H. pylori. We validated HeliSAL™, and comment here on its usefulness in prevalence surveys. One hundred and ninety-six patients receiving endoscopy at a clinic in New Zealand provided saliva samples for H. pylori assessment, which were compared to CLOtest (Delta West Pty Ltd, Western Australia) as a gold standard measure. Nineteen percent were truly H. pylori positive, 41 % were positive according to HeliSAL™. Test sensitivity was 74 % and specificity was 67 %. While HeliSAL™ is not well suited for the clinical diagnosis of H. pylori infection, it may be useful for large-scale prevalence surveys because, provided it is validated locally, mathematical adjustment can be made for misclassification. Being inexpensive, non-invasive, and easily stored and handled, HeliSAL™ may be a valuable tool for studies of the epidemiology of H. pylori.

This paper describes the relationship between different forms of nocardia infection involving the skin. The best recognized of these conditions are systemic nocardiosis and actinomycetoma due to Nocardia spp. in which the organisms are present in either filamentous or grain form respectively. Attention is drawn to evidence for the existence of a primary cutaneous form of nocardiosis which follows inoculation and in which the organisms grow in filamentous phase. It is not clear whether such cases can progress to mycetoma formation if left untreated, or whether other factors are involved. The clinical and laboratory features of these different clinical varieties of nocardia infection are discussed.

The anticipated worldwide surge in urban environments is generating ever-greater interest in the study of host–pathogen interactions in this specific type of habitat. We investigated the potential of city-inhabiting rodents to serve as the main Lyme borreliosis agents (Borrelia spp.) reservoir. We also tried to verify if anthropogenic disturbances changing the vertebrate species community composition may also alter the scheme of Borrelia spp. circulation. A total of 252 Apodemus mice (A. agrarius, A. flavicollis, A. sylvaticus) were captured in Warsaw (Poland), at sites classified into different zones of anthropogenic disturbance, ranging from suburban forests to municipal parks strictly in the city centre. Borrelia spp. infection, ascertained based on bacterium DNA presence in the rodents’ blood, was found only in A. agrarius and A. flavicollis (7.6 and 6%, respectively). Only one species from the Borrelia genus – the mammal-associated species B. afzelii – was found in the mice studied. We found no statistical evidence of a correlation between infection in Apodemus mice and the zone of anthropogenic disturbance where the mice were caught. Non-homogeneous concentrations of Borelia spp. infected specimens within the strict city centre area suggest a lack of contact between members of particular mice subpopulations, and their responsibility for relatively high, but local Borrelia spp. infection.

Acute rheumatic fever (ARF) continues to produce a significant burden of disease in New Zealand (NZ) Māori and Pacific peoples. Serious limitations in national surveillance data mean that accurate case totals cannot be generated. Given the changing epidemiology of ARF in NZ and the major national rheumatic fever prevention programme (2012–2017), we updated our previous likely true case number estimates using capture–recapture analyses. Aims were to estimate the likely true incidence of ARF in NZ and comment on the changing ability to detect cases. Data were obtained from national hospitalisation and notification databases. The Chapman Estimate partially adjusted for bias. An estimated 2342 likely true new cases arose from 1997 to 2015, giving a mean annual incidence of 2·9 per 100 000 (95% CI 2·5–3·5). Compared with the pre-intervention (2009–2011) baseline incidence (3·4 per 100 000, 95% CI 2·9–4·0), the likely true 2015 incidence declined 44%. Large gaps in data completeness are slowly closing. During the period 2012–2015, 723 cases were identified; 83·8% of notifications were matched to hospitalisation data, and 87·2% of hospitalisations matched to notifications. Despite this improvement, clinicians need to remain aware of the need to notify atypical patients. A possible unintended consequence of the national ARF prevention programme is increased misdiagnosis.

Although the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is lasting for more than 1 year, the exposition risks of health-care providers are still unclear. Available evidence is conflicting. We investigated the prevalence of antibodies against SARS-CoV-2 in the staff of a large public hospital with multiple sites in the Antwerp region of Belgium. Risk factors for infection were identified by means of a questionnaire and human resource data. We performed hospital-wide serology tests in the weeks following the first epidemic wave (16 March to the end of May 2020) and combined the results with the answers from an individual questionnaire. Overall seroprevalence was 7.6%. We found higher seroprevalences in nurses [10.0%; 95% confidence interval (CI) 8.9–11.2] than in physicians 6.4% (95% CI 4.6–8.7), paramedical 6.0% (95% CI 4.3–8.0) and administrative staff (2.9%; 95% CI 1.8–4.5). Staff who indicated contact with a confirmed coronavirus disease 2019 (COVID-19) colleague had a higher seroprevalence (12.0%; 95% CI 10.7–13.4) than staff who did not (4.2%; 95% CI 3.5–5.0). The same findings were present for contacts in the private setting. Working in general COVID-19 wards, but not in emergency departments or intensive care units, was also a significant risk factor. Since our analysis points in the direction of active SARS-CoV-2 transmission within hospitals, we argue for implementing a stringent hospital-wide testing and contact-tracing policy with special attention to the health care workers employed in general COVID-19 departments. Additional studies are needed to establish the transmission dynamics.

1. Experiments have been carried out to estimate quantitatively the survival of Sh. sonnei at various R.H.'S and two different temperature ranges.

2. A fraction may survive for 7–10 days under favourable conditions.

3. At R.H.'S of 40–60% the organism survives less well than at higher or lower values.

4. Survival is better at temperatures of 5–10°C. than at 20–30°C.

I am very grateful to Mr T. Nash for his advice during the course of this work, and also to Col. H. J. Bensted for his comments on the MS.