A population of 488 HBsAg carrier individuals, from central Italy, classified on the basis of biochemical, clinical and histological parameters, was analysed for the presence of HBV-DNA in serum and its relationship with HBeAg/anti-HBe markers. The prevalence of HBV-DNA was 32·8% in chronic patients with biopsy-proven liver disease, and 20 and 4·3% respectively in asymptomatic carriers with and without altered ALT levels. The values in chronic patients were correlated with the histological activity.

Concordance of HBV-DNA presence and HBeAg positivity was observed in only 61·4% of cases. However HBV-DNA prevalence in sera of anti-HBe positive individuals was very low in asymptomatic carriers with normal ALT levels (2·5%). Higher values were observed in anti-HBe positive chronic patients (15·8%) and in carriers occasionally found with changes in ALT without any other clinical sign of illness (16·7%). These data would indicate that HBV-DNA is the serological marker which is most closely related to liver disease.

In an outbreak of measles in North Wales centred on a secondary school in 1991, 74 cases occurred over a period of 51 days. Before the outbreak started, 27 % pupils did not have a history of measles or immunization and were considered susceptible. Active case rinding and identification and vaccination of susceptible contacts commenced after the fourth generation of cases and further reduced the pool of susceptible schoolchildren from 17%, at the onset of the vaccination campaign, to 8%. A fifth generation of cases did not occur. Delays in diagnosis (mean 2·8 days) and notification (mean 6·1 days) hampered control. There was no evidence of primary vaccine failure (observed vaccine efficacy 97%). Sixty-nine (93%) cases were considered preventable. Reasons for the apparent success of the intervention are discussed.

Summarising the results obtained in this series of experiments, it would appear that, in the case of Bact. aertrycke infection spreading among a closed community of mice:

(1) The character and severity of the epidemic are mainly determined by the virulence of the infecting bacterial strain.

(2) Strains of high virulence may give rise to non-fatal persistent infections, maintaining their full virulence over long periods of time within the spleens of the infected mice.

(3) Strains of low virulence may persist for long periods of time within such closed populations, spreading to some extent among the mice at risk, causing occasional deaths, and leading to an appreciable number of latent infections.

(4) It would appear that virulence and power to spread are highly corre lated.

1. Refection occurs as a rule in rats receiving diets containing raw potato starch.

2. Rats were maintained for one year on a diet deficient in the vitamin B complex and containing raw potato starch. Two of them attained a weight of almost 300 grm. and made sustained gains at a rate of almost 4 grm. daily.

3. Rapid decline, symptoms of vitamin B1 and B2 deficiency and death were observed in these rats after their diet had been steamed.

4. Steaming under identical conditions does not alter the vitamin B (complex) content of other diets.

Five children with a neuroendocrine tumour (NET) of the appendix associated with a parasitic bowel infection are described, and the possibility of inflammation-triggered carcinogenesis is discussed. Schistosoma haematobium is linked primarily to bladder cancer but it has been reported in association with several other histotypes, including NETs of the gastrointestinal tract. Conversely, Enterobius vermicularis has not yet been claimed to participate in the onset of pre-cancerous conditions or tumours. The rare occurrence of contemporary appendiceal NETs and parasitic infection, raises the intriguing hypothesis of an inflammation-related carcinogenesis, although a cause–effect relationship cannot be established. Larger international series of childhood appendiceal NETs, which also include countries with higher prevalence of parasitic bowel infections, are needed to further clarify this possible cause–effect relationship.

Social networks facilitate the transmission of hepatitis C virus (HCV) in people who inject drugs (PWID). The aim of this study was to assess how certain network structural characteristics are related to HCV infections in PWID and to determine the most susceptible individuals for HCV transmission in a network of PWID. PWID (N = 80) from central China were recruited from a previous follow-up case-control study. Demographic and behavioural information was obtained from a computerized database for each group. HCV RNA was extracted from blood specimens. Sequences were used to construct a phylogenetic tree and to determine genetic distances. Socio-metric social links were established between participants. Network measures were calculated using UCINET. Three HCV genotypes were identified, covering five subtypes. The density of the social networks for the whole sample (N = 80), case group (n = 31) and control group (n = 49) was 0.038, 0.054 and 0.008, respectively. PWID infected with HCV were in frequent contact with others within their group. There were four pairs of nodes with genotypic distances of 0.000 that were identified and clustered in subtypes 6a and 1b; each subject pair was linked and found in one clique. Three of the five most active nodes were infected with HCV. These three nodes served as a bridge, contributing to the connection of other nodes. These findings identify susceptible individuals for HCV transmission in PWID based on their frequent contact with others in the network. These results provide data that could be used for modelling HCV transmission patterns and in public health policies.

Staphylococci from 22 cases of toxic shock syndrome with onsets between 1981 and March 1983 have been studied. Another four cases were detected by abstract surveillance. Three of these patients died. The case histories show that the syndrome occurs in women during menstruation as well as in males and in children, and is associated with Staphylococcus aureus infections.

The production of enterotoxins (A, B, C) and toxic shock toxin by S. aureus isolates from toxic shock syndrome was investigated. Twenty-two of the 23 isolates were found to be toxigenie: 7 produced enterotoxin A, 8 produced enterotoxin B, 3 produced enterotoxin C and 13 produced toxic shock toxin. The latter was found with enterotoxin A in five cases, and with enterotoxins A and B in only one case.

Sixty-three percent of 40 S. aureus strains isolated from the vagina of patients with diseases other than toxic shock syndrome produced toxin; eight of these strains produced toxic shock toxin.

In a recent publication1 I described a gas analysis apparatus suitable for rapid and accurate laboratory work. This apparatus is, however, somewhat cumbrous, and cannot easily be conveyed from place to place, as is very often required in investigations relating to questions of hygiene. It also occupies a good deal of working space in a laboratory, as it cannot be moved from its place without a good deal of trouble. On the other hand the already existing forms of portable gas analysis apparatus for technical work are too inaccurate for many of the requirements of work in hygiene and physiology. I have therefore designed an apparatus with a view to meeting these defects as far as possible2.

Sixty-three environmental water samples from various sources were examined for the presence of Legionella pneumophila with a commercially available direct fluorescent monoclonal antibody (GS), an indirect fluorescent antibody test (IFAT) and culture. GS detected L. pneumophila in 94% and 100% of environmental water samples which were culture and IFAT positive for L. pneumophila, respectively. IFAT detected 69% of L. pneumophila culture positive samples. Cultures of L. pneumophila serogroups 1 to 12, 14 and non L. pneumophila bacteria which may be found in water, and bacteria containing non-specific binding proteins, were stained by GS and IFAT. GS identified all serogroups of L. pneumophila and did not cross react with any non-L. pneumophila bacteria. L. pneumophila in environmental samples was easy to detect against a clear dark background when stained with GS.

Recent infection testing algorithms (RITA) for HIV combine serological assays with epidemiological data to determine likely recent infections, indicators of ongoing transmission. In 2016, we integrated RITA into national HIV surveillance in Ireland to better inform HIV prevention interventions. We determined the avidity index (AI) of new HIV diagnoses and linked the results with data captured in the national infectious disease reporting system. RITA classified a diagnosis as recent based on an AI < 1.5, unless epidemiological criteria (CD4 count <200 cells/mm3; viral load <400 copies/ml; the presence of AIDS-defining illness; prior antiretroviral therapy use) indicated a potential false-recent result. Of 508 diagnoses in 2016, we linked 448 (88.1%) to an avidity test result. RITA classified 12.5% of diagnoses as recent, with the highest proportion (26.3%) amongst people who inject drugs. On multivariable logistic regression recent infection was more likely with a concurrent sexually transmitted infection (aOR 2.59; 95% CI 1.04–6.45). Data were incomplete for at least one RITA criterion in 48% of cases. The study demonstrated the feasibility of integrating RITA into routine surveillance and showed some ongoing HIV transmission. To improve the interpretation of RITA, further efforts are required to improve completeness of the required epidemiological data.

Tuberculosis (TB) in older people is a significant public health problem in low TB-incidence countries. Older persons have increased TB incidence, higher reactivation and mortality. A delay in diagnosis and initiation of TB treatment in patients with atypical clinical and radiological features is a significant factor of widespread transmission. This study aimed to evaluate the cost-effectiveness of interferon-gamma release assays [IGRAs; QuantiFERON®-TB Gold In-Tube (QFT) and T-SPOT®.TB (T-SPOT)] compared to the tuberculin skin test (TST) and chest X-ray (CXR) examination for TB screening for nursing homes. Decision trees and Markov models were constructed using a societal perspective on a lifetime horizon. Seven strategies: no screening, TST, QFT, T-SPOT, TST followed by QFT, TST followed by T-SPOT, and CXR were considered. QFT [US$ 401·9, 4·36 707 QALY (year 2014 values)] was the most cost-effective at the willingness-to-pay level of US$ 50 000/QALY gained. TST followed by QFT was the most cost-effective in residents with comorbidities. CXR was less cost-effective. Cost-effectiveness was sensitive to latent TB infection (LTBI) rate and bacillus Calmette-Guérin vaccination rate. Effective LTBI screening using IGRA is recommended to prevent TB transmission not only in nursing homes but also in local communities in low-incidence countries.

We aimed to develop a prediction rule for urinary tract infections (UTIs) in patients with type 2 diabetes mellitus (DM2). A 12-month prospective cohort study was conducted in patients with DM2 aged ⩾45 years to predict the occurrence of recurrent UTIs in women and lower UTIs in men. Predictors for recurrent UTI in women (n=81, 2%) and lower UTIs in men (n=93, 3%) were age, number of general practitioner (GP) visits, urinary incontinence, cerebrovascular disease or dementia. In women, renal disease was an additional predictor. The optimum corrected area under the receiver-operating curve (AUC) was 0·79 (95% CI 0·74–0·83) for women and 0·75 (95% CI 0·70–0·80) for men. Using a cut-off score of 4, women with a lower risk assignment had a probability of 0·3% for the outcome. For a cut-off score of 6, women with a higher risk assignment had a probability of 5·8%. For men these figures were 0·8 and 7·1 for a cut-off score of 2 and 4, respectively. Simple variables can be used for the risk stratification of patients.

Variations in bacteria may be said to fall into two classes (1) those which are temporary, and dependent on the environment, the bacteria tending to return to the original type when subculture is made on ordinary media; and (2) those which are fixed, and persist after repeated subcultures on ordinary indifferent media.

Co-receptor tropism has been identified to correlate with HIV-1 transmission and the disease progression in patients. A molecular epidemiology investigation of co-receptor tropism is important for clinical practice and effective control of HIV-1. In this study, we investigated the co-receptor tropism on HIV-1 variants of 85 antiretroviral-naive patients with Geno2pheno algorithm at a false-positive rate of 10%. Our data showed that a majority of the subjects harboured the CCR5-tropic virus (81.2%, 69/85). No significant differences in gender, age, baseline CD4+ T-cell counts and transmission routes were observed between subjects infected with CXCR4-tropic or CCR5-tropic virus. The co-receptor tropism appeared to be associated with the virus genotype; a significantly more CXCR4-use was predicted in CRF01_AE infections whereas all CRF07_BC and CRF08_BC were predicted to use CCR5 co-receptor. Sequences analysis of V3 revealed a higher median net charge in the CXCR4 viruses over CCR5 viruses (4.0 vs. 3.0, P < 0.05). The predicted N-linked glycosylation site between amino acids 6 and 8 in the V3 region was conserved in CCR5 viruses, but not in CXCR4 viruses. Besides, variable crown motifs were observed in both CCR5 and CXCR4 viruses, of which the most prevalent motif GPGQ existed in both viral tropism and almost all genotypes identified in this study except subtype B. These findings may offer important implications for clinical practice and enhance our understanding of HIV-1 biology.

In all countries which make statistical returns, attention has been directed to the large proportion of children failing to complete one year of life. Even the most highly civilised races lose in this way more than ten per cent, of their potential citizens as will appear from the data contained in the following table (Deutsche Sterbetafeln, 1910).

Seventy-three cultures of Clostridium difficile isolated both during, and in the period immediately following, an outbreak of infection in a group of three hospitals, were characterized by one-dimensional sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE) of whole-cell proteins. Each protein pattern was characterized by the presence of one or two dense bands which were highly reproducible. The protein patterns were used as the basis for a numerical analysis which divided the strains into five phenons (electrophoretic or EP types). The majority, 60 of the 73 cultures, belonged to a single phenon which included strains from both patients and the environment. We conclude that high-resolution SDS–PAGE of proteins provides an effective method for typing C. difficile and therefore for tracing the possible spread of epidemic strains in hospitals and other institutions, thereby allowing a better understanding of the epidemiology of the organism.

Minimal quantities of active vaccinia virus in the form of a purified elementary body suspension were injected subcutaneously into rabbits. The amount administered was about 10 minimal infective doses as measured by intracutaneous titration and tissue culture assay: this is equivalent to about 1·3± 10−5μg of virus protein. The immune response to this minimal quantity of virus was determined by complement-fixation and virus neutralization tests and also by skin sensitivity tests. The results indicated that viral proliferation occurred to an extent sufficient to sensitize the tissues to the virus protein. Measurable amounts of antibody could also be detected in about one half of the experimental animals. A second inoculation of virus produced a considerable augmentation of the immune response. Viral proliferation must have taken place in order to evoke this immunity, but infection always remained at the subclinical level. The results were much improved when the infecting does of virus was incorporated in an adjuvant. DPT-polio vaccine functioned well as adjuvant but equally good results were obtained with a solution of polyvinylpyrrolidone. The latter substance also has valuable properties as a protective colloid and is thus able to maintain the viability of the virus over long periods of time.

On the evidence provided by these experiments it is suggested that an adequate immunity to smallpox might be achieved in man by similar methods. A primary sensitization could be achieved by incorporating a very small amount of active virus in one of the prophylactics given as a routine in the early months of life. This could be followed by normal jennerian vaccination a few months later; or the second inoculation of virus could also be incorporated in amultivalent prophylactic. For adults, a somewhat similar two-stage immunization would be required.

It is hoped that the publication of these preliminary experiments will encourage other investigators to continue what promises to be an important line of research.

All assays involving the use of monkey kidney tissue cultures were carried out by my former assistant Mr Edmund Bischoff. His help is gratefully acknowledged.

A latent tuberculosis infection (LTBI) prevalence survey was conducted using tuberculin skin test (TST) and Quantiferon test (QFT) in 1218 healthcare workers (HCWs) in Medellín, Colombia. In order to improve the prevalence estimates, a latent class model was built using a Bayesian approach with informative priors on the sensitivity and specificity of the TST. The proportion of concordant results (TST+,QFT+) was 41% and the discordant results contributed 27%. The marginal estimate of the prevalence P(LTBI+) was 62·1% [95% credible interval (CrI) 53·0–68·2]. The probability of LTBI+ given positive results for both tests was 99·6% (95% CrI 98·1–99·9). Sensitivity was 88·5 for TST and 74·3 for QFT, and specificity was 87·8 for TST and 97·6 for QFT. A high LTBI prevalence was found in HCWs with time-accumulated exposure in hospitals that lack control plans. In a context of intermediate tuberculosis (TB) incidence it is recommended to use only one test (either QFT or TST) in prevalence surveys or as pre-employment tests. Results will be useful to help implement TB infection control plans in hospitals where HCWs may be repeatedly exposed to unnoticed TB patients, and to inform the design of TB control policies.

Transmission of hepatitis C (HCV) in Pakistan is a continuing public health problem; 15 years ago it was linked to the practice of reusing therapeutic instruments in healthcare settings. We sought to examine current risk factors for HCV transmission in a hospital population in Karachi, Pakistan. We enrolled 300 laboratory-confirmed HCV-positive participants and 300 laboratory-confirmed HCV-negative participants from clinics at Indus Hospital. Independent and significant risk factors for both men and women were: receiving ⩾12 injections in the past year, blood transfusions, having had dental work performed, and delivery in hospital or transfusion for women. Interestingly, being of Mohajir origin or born in Sindh province were protective. Encouragingly, a strong protective effect was observed for those that reported bringing their own needle for injections (59%). The widespread reuse of therapeutic needles in healthcare settings in Karachi remains a major driver of the HCV epidemic.

Prevention of secondary household transmission of Shiga toxin-producing Escherichia coli (STEC) is important in outbreak settings. We examined factors contributing to secondary household transmission during STEC outbreaks in daycare centres in Japan. Suspected STEC outbreaks in daycare centres were identified by the National Epidemiological Surveillance of Infectious Diseases. Questionnaires were sent to local health centres that responded to outbreaks. Secondary household transmission rates were calculated, and factors affecting secondary household transmission rate were analysed by multilevel analysis. The secondary household transmission rates in 16 outbreaks ranged from 0% to 34·4% (median 4·4%). The highest rate (23·0%) was observed in siblings aged 6–9 years, and the infection rate was significantly higher for mothers than for fathers and grandparents (P < 0·05). Using multilevel analysis, the following variables were selected in the best model: information provided face-to-face (vs. letter or telephone) to families of children in daycare centres (at initial response), STEC type and lag time (days) between onset and providing information. Early response and hygiene education by visiting local health centre staff may be effective measures to prevent secondary household transmission in STEC outbreaks. Hygiene education should be emphasized for children aged 6–9 years, as well as for younger children.