Optimal antiretroviral strategies for HIV-infected patients still need to be established. To this end a decision tree including different antiretroviral strategies that could be adopted for HIV-infected patients was built. A 10-year follow-up was simulated by using transitional probabilities estimated from a large cohort using a time-homogeneous Markov model. The desired outcome was for patients to maintain a CD4 cell count of >500 cells/mm3 without experiencing AIDS or death. For patients with a baseline HIV viral load ⩾5 log10 copies/ml, boosted protease inhibitor-based immediate highly active antiretroviral therapy (HAART) allowed them to spend 12% more time with CD4 ⩾500/mm3 than did delayed HAART (6·40 vs. 5·69 and 5·57 vs. 4·90 years for baseline CD4 ⩾500 and 350–499/mm3, respectively). In patients with a baseline HIV viral load ⩽3·5 log10 copies/ml, delayed HAART performed better than immediate HAART (6·43 vs. 6·26 and 5·95 vs. 5·18 for baseline CD4 ⩾500 and 350–499/mm3, respectively). Immediate HAART is beneficial in patients with a baseline HIV viral load ⩾5 log10 copies/ml, whereas deferred HAART appears to be the best option for patients with CD4 ⩾350/mm3 and baseline HIV viral load <3·5 log10 copies/ml.

A study of the distribution of subtypes ad and ay among sera from hepatitis B antigen-positive subjects in North West England and North Wales revealed a marked contrast between symptomless carriers among whom ad predominated and patients with acute hepatitis the majority of whom were ay. Those with hepatitis associated with drug addiction or other forms of ‘needle transmission’ were almost all of subtype ay. On the other hand in cases of ‘sporadic’ hepatitis without evidence of parenteral exposure subtypes ad and ay are about equally distributed.

These findings are similar to those reported from other countries in Northern Europe and North America. Although geographical and social factors clearly affect the distribution of the two subtypes it is suggested that the virus of subtype ay may be more readily transmitted than subtype ad by parenteral routes involving small amounts of blood.

Two hundred and one strains of Staphylococcus aureus isolated from in-patients and out-patients were examined for sensitivity to antibiotics, heavy-metal ions and ethidium bromide and for phage-typing pattern.

Heavy-metal ion resistance was less frequent than reported in previous studies and was as frequent in penicillinase non-producing as producing strains. ‘Methicillin-resistant’ strains were resistance to ethidium bromide and mercury. Resistance to heavy-metal ions, including cadmium, may bo becoming less common amongst clinical isolates of S. aureus.

Electron microscopic observation of negatively stained preparations of frozen and thawed suspensions of T4Bo phage clearly separated the morphological changes produced by low-temperature salt denaturation from those produced by eutectic phase changes. Salt denaturation caused contraction of tail sheaths. Eutectic phase changes appeared to cause two separate lesions. Firstly the tail sheath was disjointed 18–22 nm. below the collar and the tail core was disjointed at 40–60 nm. below the collar, giving rise to separated heads with a small tail remnant, and separated tails in which the sheath remarkably remained in its extended form. Secondly, tears were seen in the head membranes of particles with collapsed empty heads. In all the experiments the percentage of normal phage particles counted electron-microscopically was close to the percentage of viable phage as determined by plaque assay.

A transportable surgery cross-flow unit has been tested under ‘operational conditions’. By the use of artificial aerosols and a volunteer surgical team, or dummies, it was found that, at an air velocity of 0·45 m./sec., a detectable transfer to above the table occurred only when quite highly concentrated aerosols (of more than 103·6 bacteria/m.3 of air or more) existed underneath the table. The short disappearance time under these conditions and the quite stable flow pattern above the table found when a surgical team was working, standing along both sides of the table, make it unlikely that an aerosol of detectable concentration can develop during surgery, at this site. The chance that particles, liberated from the heads of the surgical team, settle on the table, was found to be strongly reduced when a cross-flow tunnel operated at an air velocity of 0·45 m./sec. The transfer from outside the unit to the inside was prevented by closing the upper part of the open front side.

Two hundred and twenty-two infants and fifty-one staff were examined for carriage of Staphylococcus pyogenes and Gram-negative bacilli, and the presence of these bacteria in the ward environment was also investigated. Staphylococci were phage-typed and tested for sensitivity to antibiotics. Assessment of clinical infection caused by these bacteria was made.

Infant carriage of Staphylococcus pyogenes was maximal on the sixth day, 73·1 % of umbilical swabs yielding significant growth. Carriage of Gram-negative bacilli was maximal on the fifth day, 31·7% of umbilical swabs being positive. Where special nursing was enforced, i.e. premature baby unit, isolation of Gram-negative bacilli was very infrequent.

The low nasal carriage of staphylococci seen in infants and nursing staff is attributed to traces of penicillinase-resistant penicillins in the ward air.

Staphylococcus pyogenes was recovered from 23 % of ward surfaces, and constituted 0·7% of the air-borne flora. In contrast, Gram-negative bacilli were recovered from 4·7 % of surfaces, and composed only 0·15% of the air-borne flora.

Phage group I constituted 73·0, 44·9 and 41·2% of strains from infants, staff and ward environment respectively.

Antibiograms were grouped into three categories, A, B and C. Category A (sensitive to chloramphenicol, erythromycin and methicillin but penicillin-resistant) composed 79·0% of infants' strains, being found mostly in group I, but was rare among staff strains.

Of 54 specimens taken from 40 infants showing evidence of infection, Staphylococcus pyogenes was isolated from 16, of which 14 were category A. Gram-negative bacilli were isolated 7 times. Only 21 infants required antibiotic therapy (9·3%) and none were infected with Gram-negative bacilli—this contrasts with the frequency of these bacilli in nursery infection today.

Ward air is considered to be the main depot of Staphylococcus pyogenes. Infant ‘dispersers’ are probably the principal source of the air-borne staphylococci. Infants and staff abstract from the air those staphylococci which become their colonizing strains. No transfer is thought to occur from the staff to the infants. Transmission of Gram-negative bacilli is similar in that the infants are the principal source and the air the main depot of these bacteria. Nasal colonization by Gram-negative bacilli is low, this is possibly due to poor colonizing properties. Infant umbilical carriage almost certainly results from endogenous faecal spread.

We are grateful to Dr J. C. Gould, Director, Central Microbiological Laboratories, Edinburgh, for his continued interest and advice, and to Mr J. C. Ferguson and Mrs M. M. Winton for skilled technical assistance. This study would not have been completed without the co-operation of Sisters McCartney and Struthers and their nursing staff.

Acute respiratory infections (ARIs) are the most important infectious cause of death, but there is less information of their burden in the community. This study describes the burden of ARI in a cohort of 50 Iranian families visited weekly over 2 months. Eighty-one out of 113 (72%) children and 29/103 (28%) adults had a total of 124 episodes of ARI. Seventy-five per cent of the episodes occurring in children were primary/co-primary compared to 40% of those in adults (P<0·01). Children were more likely to be the first symptomatic cases and infections were frequently transmitted within the family. Frequencies were lowest among adults, low among infants aged <6 months and highest among children aged <5 years (P<0·01). Winter episodes occurred more frequently in January (P<0·01). The high frequency and apparent transmissibility of ARI in this cohort highlights its enormous burden in the community.

Physiologists have recognized for a long time that stuffiness in a close atmosphere is not due to diminution of oxygen or excess of carbon dioxide in the air breathed, or to any other impurity in the air. Such feelings are now shown to be due to the effect of longer infra-red rays on the skin, and are accompanied by a reflex narrowing of the air-ways of the nose and lungs. These effects are set aside by cool air acting on the skin and in many people also by shorter infra-red rays from bright sources of heat. This is why some people are much more comfortable with a bright source of heat than with a dark or dull red one. When people go out of doors to get a “breather”, or stand before an open window during physical exercises, they are instinctively using the stimulus of cold to widen their air-tubes. In open air treatment, and when sleeping with an open window, the same effect is obtained.

All rooms should be adequately ventilated with cool air to prevent stuffy feelings, and keep the air-ways open. Such ventilation will, at the same time, sweep away infection spread by “carriers”.

Partial obstruction of the air-tubes hinders the passage of blood through the lungs; it is this which causes failure of breathing when the obstruction is considerable.

Bleeding is of value because it relieves to a certain extent the impeded circulation.

Breathing through a narrow tube can be used as a test of fitness. An airway gauge has been designed for making such a test.

A prospective study of hepatitis that began in 1968 and continues to include more than half the dialysis units in the United Kingdom shows that type B infection has been completely controlled in such units since the last outbreak ended in 1973. Though occasionally a single patient has developed hepatitis B surface antigenaemia in the course of dialysis or after transplantation, the infection has not spread to other patients or staff in the survey units.

A detailed analysis of the results in 1974–75 shows clustering of patients with raised aminotransferase levels in about one-fifth of the units but, unlike past outbreaks of hepatitis B, these clusters are not accompanied by clinical hepatitis among staff. The possibility that some of the clusters are caused by hepatitis viruses other than type A or B is discussed. It is concluded that, when reliable tests for type non-A non-B infections become available, the continued existence of the survey will allow prompt assessment of any viral hepatitis problems that may still exist in UK units.

Brucellosis remains one of the main zoonoses worldwide. Epidemiological data on human brucellosis in Spain are scarce. The objective of this study was to assess the epidemiological characteristics of inpatient brucellosis in Spain between 1997 and 2015. A retrospective longitudinal descriptive study was performed. Data were requested from the Health Information Institute of the Ministry of Health and Equality, which provided us with the Minimum Basic Data Set of patients admitted to the National Health System. We also obtained data published in the System of Obligatory Notifiable Diseases. A total of 5598 cases were registered. The period incidence rate was 0.67 (95% CI 0.65–0.68) cases per 100 000 person-years. We observed a progressive decrease in the number of cases and annual incidence rates. A total of 3187 cases (56.9%) came from urban areas. The group most at risk comprised men around the fifth decade of life. The average (±s.d.) hospital stay was 12.6 days (±13.1). The overall lethality rate of the cohort was 1.5%. The number of inpatients diagnosed with brucellosis decreased exponentially. The group of patients with the highest risk of brucellosis in our study was males under 45 years of age and of urban origin. The lethality rate has reduced to minimum values. It is probable that hospital discharge records could be a good database for the epidemiological analysis of the hospital management of brucellosis and offer a better information collection system than the notifiable diseases system (EDO in Spanish).

(1) Samples of faeces of 391 cows in apparently good health have been examined and it has been demonstrated that 6 (1.53 per cent.) of the cows were excreting tubercle bacilli.

(2) When the faeces of almost all the cows on founrteen farms were examined it was found that five cows on four farms were excreting tubercle bacilli.

Our thanks are due to the Medical Research Council for the grant which enabled us to carry out this investigation.

To compare the epidemiologic features (e.g. settings and transmission mode) and patient clinical characteristics associated with outbreaks of different norovirus (Nov) strains, we retrospectively analysed data of Nov outbreaks occurring in Guangzhou, China from 2012 to 2018. The results suggested that outbreaks of Nov GII.2, GII.17 and GII.4 Sydney exhibited different outbreak settings, transmission modes and symptoms. GII.2 outbreaks mainly occurred in kindergartens, elementary and high schools and were transmitted mainly through person-to-person contact. By contrast, GII.4 Sydney outbreaks frequently occurred in colleges and were primarily associated with foodborne transmission. Cases from GII.2 and GII.17 outbreaks reported vomiting more frequently than those from outbreaks associated with GII.4 Sydney.

The recent reinforcement of CoV surveillance in animals fuelled by the COVID-19 pandemic provided increasing evidence that mammals other than bats might hide further diversity and play critical roles in human infectious diseases. This work describes the results of a two-year survey carried out in Italy with the double objective of uncovering CoV diversity associated with wildlife and of excluding the establishment of a reservoir for SARS-CoV-2 in particularly susceptible or exposed species. The survey targeted hosts from five different orders and was harmonised across the country in terms of sample size, target tissues, and molecular test. Results showed the circulation of 8 CoV species in 13 hosts out of the 42 screened. Coronaviruses were either typical of the host species/genus or normally associated with their domestic counterpart. Two novel viruses likely belonging to a novel CoV genus were found in mustelids. All samples were negative for SARS-CoV-2, with minimum detectable prevalence ranging between 0.49% and 4.78% in the 13 species reaching our threshold sample size of 59 individuals. Considering that within-species transmission in white-tailed deer resulted in raising the prevalence from 5% to 81% within a few months, this result would exclude a sustained cycle after spillback in the tested species.

A survey of mild respiratory disease in a primary school was undertaken over a 2-year period to determine which of the newer respiratory viruses were responsible for these illnesses.

The over-all isolation rate was low but a wide variety of viral agents was isolated.

None of these caused epidemics but it is suggested they may be the cause of a low but constant absentee-rate throughout the year.

Household transmission plays a key role in the spread of COVID-19 through populations. In this paper, we report on the transmission of COVID-19 within households in a metropolitan area in Australia, examine the impact of various factors and highlight priority areas for future public health responses. We collected and reviewed retrospective case report data and follow-up interview responses from households with a positive case of the Delta COVID-19 variant in Queensland in 2021. The overall secondary attack rate (SAR) among household contacts was 29.6% and the mean incubation period for secondary cases was 4.3 days. SAR was higher where the index case was male (57.9% vs. 14.3%) or aged ≤12 years (38.7% vs. 17.4%) but similar for adult contacts that were double vaccinated (35.7%) and unvaccinated (33.3%). Most interview participants emphasised the importance of clear, consistent and compassionate health advice as a key priority for managing outbreaks in the home. The overall rate of household transmission was slightly higher than that reported in previous studies on the wild COVID-19 variant and secondary infections developed more rapidly. While vaccination did not appear to affect the risk of transmission to adult subjects, uptake in the sample was ultimately high.

The purpose of the present study was to reconstruct the phylogeny of dengue virus serotype 4 (DENV-4) that was circulating in Espírito Santo state, Brazil, in 2013 and 2014, and to discuss the epidemiological implications associated with this evolutionary hypothesis. Partial envelope gene of eight DENV-4 samples from Espírito Santo state were sequenced and aligned with 72 worldwide DENV-4 reference sequences from GenBank. A phylogenetic tree was reconstructed through Bayesian Inference and the Time of the Most Recent Common Ancestor was estimated. The study detected the circulation of DENV-4 genotype II in Espírito Santo state, which was closely related to strains from the states of Mato Grosso collected in 2012 and of São Paulo sampled in 2015. This cluster emerged around 2011, approximately 4 years after the entry of the genotype II in Brazil through its northern states, possibly imported from Venezuela and Colombia. This is so far the first phylogenetic study of the DENV-4 circulating in Espírito Santo state and shows the importance of an internal route of dengue viral circulation in Brazil to the introduction of the virus into this state.

Patients with a clinical diagnosis of dengue but negative by serological testing were studied for rubella infection. Paired sera were obtained from 69 patients during an outbreak in Yucatán, México. The presence of specific anti-viral IgM in the acute sera was considered as diagnostic for rubella infection. The immunoglobulin was determined by measuring the difference in the inhibition of hemagglutination between the non-reduced and the reduced fractionated sera. Immunoglobulins were separated by sucrose density centrifugation. Acute rubella infection was found in 7 (10·1%) of the patients. These results demonstrate active rubella infection in patients clinically diagnosed as dengue.

Measles is a target for elimination in all six WHO regions by 2020, and over the last decade, there has been considerable progress towards this goal. Surveillance is recognised as a cornerstone of elimination programmes, allowing early identification of outbreaks, thus enabling control and preventing re-emergence. Fever–rash surveillance is increasingly available across WHO regions, and this symptom-based reporting is broadly used for measles surveillance. However, as measles control increases, symptom-based cases are increasingly likely to reflect infection with other diseases with similar symptoms such as rubella, which affects the same populations, and can have a similar seasonality. The WHO recommends that cases from suspected measles outbreaks be laboratory-confirmed, to identify ‘true’ cases, corresponding to measles IgM titres exceeding a threshold indicative of infection. Although serological testing for IgM has been integrated into the fever–rash surveillance systems in many countries, the logistics of sending in every suspected case are often beyond the health system's capacity. We show how age data from serologically confirmed cases can be leveraged to infer the status of non-tested samples, thus strengthening the information we can extract from symptom-based surveillance. Applying an age-specific confirmation model to data from three countries with divergent epidemiology across Africa, we identify the proportion of cases that need to be serologically tested to achieve target levels of accuracy in estimated infected numbers and discuss how this varies depending on the epidemiological context. Our analysis provides an approach to refining estimates of incidence leveraging all available data, which has the potential to improve allocation of resources, and thus contribute to rapid and efficient control of outbreaks.

This paper describes the practical use of social network diagrams in the management of an outbreak of Escherichia coli O157 (VTEC) in a primary school in London. The diagrams were created during the outbreak to establish the extent and nature of person-to-person transmission in the cases and their contacts. The diagrams supported a tailored public health action, and hence aided in the control of the outbreak. We conclude that for selected infectious diseases, social network diagrams can provide a valuable tool in the management of an outbreak.

Persistent methicillin-resistant Staphylococcus aureus (MRSA) infection in cystic fibrosis (CF) patients has been associated with a more rapid decline in lung function, increased hospitalisation and mortality. The aim of this study was to evaluate the clonal relationships among 116 MRSA isolates from 12 chronically colonised CF pediatric patients over a 6-year period in a Rio de Janeiro CF specialist centre. Isolates were characterised by antimicrobial resistance, SCCmec type, presence of Panton-Valentine Leukocidin (PVL) genes and grouped according to DNA macrorestriction profile by pulsed-field gel electrophoresis (PFGE) and spa gene type. High resistance rates were detected for erythromycin (78%) and ciprofloxacin (50%) and SCCmec IV was the most common type (72.4%). Only 8.6% of isolates were PVL positive. High genetic diversity was evident by PFGE (39 pulsotypes) and of nine that were identified spa types, t002 (53.1%) and t539 (14.8%) were the most prevalent. We conclude that the observed homogeneity of spa types within patients over the study period demonstrates the persistence of such strain lineages throughout the course of chronic lung infection.