Using data from a cohort study conducted by the Veterinary Laboratories Agency (VLA), evidence of spatial clustering at distances up to 30 km was found for S. Agama and S. Dublin (P values of 0·001) and borderline evidence was found for spatial clustering of S. Typhimurium (P=0·077). The evolution of infection status of study farms over time was modelled using a Markov Chain model with transition probabilities describing changes in status at each of four visits, allowing for the effect of sampling visit. The degree of geographical clustering of infection, having allowed for temporal effects, was assessed by comparing the residual deviance from a model including a measure of recent neighbourhood infection levels with one excluding this variable. The number of cases arising within a defined distance and time period of an index case was higher than expected. This provides evidence for spatial and spatio-temporal clustering, which suggests either a contagious process (e.g. through direct or indirect farm-to-farm transmission) or geographically localized environmental and/or farm factors which increase the risk of infection. The results emphasize the different epidemiology of the three Salmonella serovars investigated.

1. The paper records the result of a study of the serological types of haemolytic streptococci in scarlatina, puerperal fever, erysipelas, ear infections, tonsillitis, erythemas, etc., and normal throats, and their epidemiological relationships.

2. Tables and charts are given showing statistical records of scarlatinal cases which occurred over a period of 16 months in Edinburgh, a city with a population of about half a million inhabitants. In all there were 2287 cases. Of these 2169 were treated in an infectious diseases hospital, and were thus readily accessible for investigation. 1364 of the cases were school children. The strains of haemolytic streptococci from 1664 of the hospital-treated cases were serologically examined.

3. During an epidemic of scarlatina certain schools practically escaped, but in these there was a proportionately greater number of cases the following year, as compared with those schools which had suffered heavily the previous season.

4. Depending on the types of haemolytic fltreptococci isolated, scarlatina patients have been divided into three main categories: (1) pupils or school children, (2) “pupil-contacts” (families of pupils), and (3) “non-pupil-contacts” (famines without children of school age). The types of haemolytic streptococci found in these three groups have been correlated. There was a similarity in the types found in pupils and “pupil-contacts”, but not in those of pupils and “non-pupil-contacts”. Those types obtained from “pupil-contacts” and “non-pupil-contacts” were related. These features have been discussed.

5. Certain types of haemolytic streptococci predominated in the pupil cases. These were for the most part the epidemic types. The non-epidemic types, sporadic in appearance, were found mostly in “non-pupil-contacts”. “Pupil-contacts” occupied an intermediate position.

6. One main epidemic type ran through the three classes of patients. It was later replaced by another type.

7. The majority of cases of scarlatina which occurred in a school at a particular time were due to one type. It tended to persist despite the sporadic occurrence of other types. On occasions two types were present concurrently, but usually the one disappeared, and afterwards the other produced most of the cases.

8. The types of haemolytic streptococci in scarlatina, erysipelas, otitis media and mastoiditis, tonsillitis, and other streptococcal infections have been compared and the findings discussed. For the most part there was a correlation of types among all these conditions, and these types appeared to be responsible for a single epidemic of streptococcal infections.

9. The major epidemic types found simultaneously in the City of Edinburgh and in a small community, 12 miles distant, differed.

10. The types of haemolytic streptococci isolated from the throats of nurses in a general hospital bore little relationship to those isolated from medical officers and nurses in an infectious diseases hospital. The common epidemic types were present in the latter.

11. Correlations were shown to exist between the types of haemolytic streptococci in scarlatina patients, and those isolated from various members of their families, in 50% of the occasions in which the organisms were found.

12. The rapid change in the types occurring in the nasopharynx and the problem of immunity have been investigated and discussed in the case of a person exposed to massive infections with haemolytic streptococci.

13. Haemolytic streptococci on the handkerchiefs of scarlatina patients were viable after 4 weeks in most cases and after 7 weeks in two cases. After 15 weeks they were all dead.

14. Haemolytic streptococci were isolated from toys and fruit taken from scarlatina patients.

Certain strains of verotoxigenic Escherichia coli (VTEC), and in particular those belonging to serogroup O157, cause attaching and effacing (AE) lesions of the host gut mucosa during pathogenesis. The mechanisms involved with bacterial attachment and the destruction of microvilli are determined by a cluster of genes within the LEE region, which also encode five secreted proteins. Sera from patients with antibodies to the lipopolysaccharide (LPS) of E. coli O157 and other VTEC were tested for antibodies to these secreted proteins. Twenty-one of 34 (62%) sera with antibodies to the lipopolysaccharide (LPS) of E. coli O157 also contained antibodies to one or more of the secreted proteins. Five of 12 sera containing antibodies to the LPS of a range of other VTEC serogroups also contained antibodies to 1 or more of the 5 secreted proteins, as did 16 of 70 (23%) sera from patients with haemolytic uraemic syndrome (HUS), haemorrhagic colitis (HC) or diarrhoea, but without bacteriological evidence of infection with VTEC and which did not contain antibodies to VTEC serogroups O5, O115, O145, O153 or O157. The detection of serum antibodies to secreted proteins may provide additional information for interpreting the results of established lipopolysaccharide-based VTEC serology.

The environment of two contiguous surgical wards was examined over a period of twelve months by means of a slit sampler, settle plates and blanket sweep plates. At the same time, nasal swabs were taken each week from the patients and all cases of sepsis examined bacteriologically.

Phage typing of more than 3600 isolations of Staph. aureus showed that there was one predominant strain in the air, bedding, patients' noses and infected wounds.

There was no relationship between the total number of bacteria in the ward air and the numbers of Staph. aureus.

The recovery of large numbers of Staph. aureus from the air at certain periods was associated with a high contamination rate in the blankets and with an increased incidence of staphylococcal sepsis.

Not all nasal carriers of Staph. aureus contaminated their bedding. There was evidence that some patients became nasal carriers of strains of staphylococci previously isolated from their bedding.

Some evidence was obtained that blankets may play a role in the transmission of staphylococci from patient to patient.

This work was supported by a grant from the Australian National Health and Medical Research Council. Our thanks are due to Mrs Elisabeth Bradshaw for her technical assistance and to Prof. John Loewenthal for his interest and for permission to study his wards.

The inhibitory influence of cyanuric acid on the virucidal effect of chlorine was studied. The time required for 99·9% inactivation of ten enteroviruses and two adenoviruses by 0·5 mg/l free available chlorine at pH 7·0 and 25○C was prolonged approximately 4·8–28·8 times by the addition of 30 mg/l cyanuric acid. Comparative inactivation of poliovirus 1 by free available chlorine with or without cyanuric acid revealed the following. The inactivation rate by 1·5 mg/l free available chlorine with 30 mg/l cyanuric acid or by 0·5 mg/l free available chlorine with 1 mg/1 cyanuric acid was slower than by 0·5 mg/1 free available chlorine alone. Temperature and pH did not affect the inhibitory influence of cyanuric acid on the disinfectant action of chlorine. In the swimming-pool and tap water, cyanuric acid delayed the virucidal effect of chlorine as much as in the ‚clean’ condition of chlorine-buffered distilled water. The available chlorine value should be increased to 1·5 mg/l when cyanuric acid is used in swimming-pool water.

The British genera of blowflies, if the term be restricted to members of the Muscid subfamily Calliphorinae, are Calliphora with the two species erythrocephala Mg. and Vomitoria L., Lucilia, with several species, of which the commonest in the Manchester area are caesar L. and simulatrix Pand., and Protocalliphora, withe two species azurea. Fln. and groenlandica Ztt., of which the later alone concern us.

We know, since the time of Pasteur, that repeated passage of rabies street virus from rabbit to rabbit after intracerebral inoculation, leads to a modification of its effect and the appearance of mutative characters. This takes place at a variable period of time depending upon the strain employed. The irreversibility and the permanence of these characters has led to the name of “fixed virus” once the street virus has become adapted for the rabbit.

Many contradictory articles on the infectivity of non-culturable Campylobacter jejuni can be found. We studied the effect of non-culturable C. jejuni in an in vitro assay. To prevent the potential effect of a few culturable bacteria in the non-culturable suspension, INT-407 cells, which mimic the outer cell layer in the small intestines, were exposed to culturable C. jejuni suspensions with or without non-culturable C. jejuni. The number of bacteria adhering to and/or invading INT-407 cells and the IL-8 secretion were measured. No differences were found between bacterial suspensions with or without non-culturable C. jejuni added. These findings show that non-culturable C. jejuni do not adhere to or invade INT-407 cells and do not induce an immune response. As previous studies showed a correlation between the used in vitro assays and the effect in vivo, our study strongly suggests that culturability is a good indicator of the risk for C. jejuni infection.

1. The influence of temperature on the germicidal power of selected disinfectants has been studied, and it has been found that germicides may be classified broadly into three main groups, viz.

Germicidal power (a) unaffected by rise in temperature: chiefly chemical substances, possessing reducing properties;

(b) approximately doubled by rise in temperature from 20 to 37°C.—phenol, alcohol;

(c) increased as much as 10 or 20-fold by the same temperature rise: oxidising agents.

2. The effect of temperature on bactericidal action is different for B. coli and B. fluorescens, thus causing very complex changes in selective action, which are discussed in this paper.

3. The temperature coefficient for the process of protein-precipitation by phenol is 2·2 per 10°C. rise in temperature, and thus similar in magnitude to the coefficient for disinfection by phenol. This supports the view that the germicidal action of phenol is associated with its denaturating effect on the cell-proteins.

4. Previous experimental work had suggested that the bactericidal action of the quinones was due to their chemical reactivity with the simple cell-constituents, e.g. the amino-acids, rather than with the complex colloids. The temperature coefficient of the reaction between benzoquinone and glycine is, however, the normal one, viz. 2 for 10° C. rise, for chemical action, although the germicidal action of the quinones may be actually 20 times more effective at 37° than at 20° C. The presence of certain inorganic cell-constituents accelerates the velocity of reaction between quinone and glycine, but does not increase the temperature coefficient.

5. The bactericidal power of picric acid and potassium permanganate, as well as the quinones, is greatly increased by rise in temperature: and there would appear to be some other factor common to all these disinfectants associated with their high temperature coefficient.

Positive Deviance (PD) is a process to achieve a social and cultural change. This strategy has been used for the control of methicillin-resistant Staphylococcus aureus (MRSA) infection in some health institutions in the United States, but has rarely been adopted in institutions from developing countries where resources are limited. We describe our experience of PD in the control of healthcare-associated infections (HAIs) due to MRSA in a Colombian hospital with the aim of reducing HAI rates through a cultural change in processes. A time-series study was conducted based on the MRSA-HAI rate and the number of months with zero MRSA infections before and after application of PD (2001–2012). On comparing the pre-intervention and intervention periods, the mean overall rates of MRSA-HAI was 0·62 and 0·36, respectively (P = 0·0005); the number of months with zero MRSA-HAIs were 3/70 and 12/74 (odds ratio 0·264, 95% confidence interval 0·078–0·897); the percentage of MRSA-HAIs was 53·2% and 41·0%. These results are consistent with other published data. Implementation of PD was associated with a significant reduction of MRSA-HAIs, it did not involve high costs and the changes have been lasting.

1. A comparative study has been made of the life history of two groups of rats, one of which (483 animals) was maintained on an adequate diet whilst the other (556 animals) was given a ration providing a suboptimal intake of “vitamin B”. The chief defect of the second diet was probably in respect to vitamin B1.

2. The duration of life was shortened and reproduction was adversely affected by the deficiency.

3. The examination of the post-mortem records provides clear proof of a significantly greater incidence of gastro-intestinal lesions, particularly ulcerations, in the animals on the deficient diet than in the control group.

4. The deficiency of B1 did not influence the incidence or the severity of the chronic lung infection (bronchiectasis) common in laboratory rats.

5. The incidence of all other disorders was about the same in the two groups.

6. No evidence of increased susceptibility to tumours, malignant or innocent, was shown by the animals on the deficient diet. Cancerous developments arising at the site of chronic inflammatory processes (e.g. worm cysts in the liver, caecal ulcers of long standing, etc.) were not appreciably more numerous in one group than in the other.

The screening and treatment of latent tuberculosis infection (LTBI) to prevent active tuberculosis (TB) is recommended by the WHO in all HIV-infected patients. The aim of this study was to evaluate its implementation within Belgium's HIV care. A multiple-choice questionnaire was sent to 55 physicians working in the country's AIDS reference centres. Response rate reached 62%. Only 20% screened all their HIV-infected patients for LTBI. Screening methods used and their interpretation vary from one physician to another. The main barriers to the implementation of LTBI screening and treatment, as perceived by the participants, are lack of sensitivity of screening tools, risks associated with polypharmacy and toxicity of treatment. The poor coverage of LTBI screening reported here and the inconsistency in methods used raises concern. However, this was not unexpected as, in low-TB incidence countries, who, when and how to screen for LTBI remains unclear and published guidelines show important disparities. Recently, a targeted approach in which only HIV-infected patients at highest risk of TB are screened has been suggested. Such a strategy would limit unnecessary exposure to LTBI treatment. This methodology was approved by 80% of the participants and could therefore achieve greater coverage. Its clinical validation is still pending.

The properties of an atypical Brucella strain isolated from lymph node tissue of a cow slaughtered as a brucellosis reactor were examined. The organism was Gram negative and highly pleomorphic, existing as cocci, coccobacilli, rods, branched and irregular forms which stained with fluorescent antibody conjugates prepared against rough and smooth Brucella abortus strains. It produced lecithinase and required at least 15% v/v equine or bovine serum for growth. It did not need supplementary CO2 for growth, produced H2S and was inhibited by brucella dyes and partially by i-erythritol. Growth inhibition or lysis was produced by brucellaphages. The organism was not pathogenic for guinea-pigs or mice but evoked antibodies mainly to rough Brucella antigens.

This study compares the frequency and severity of influenza A/H1N1pdm09 (A/H1), influenza A/H3N2 (A/H3) and other respiratory virus infections in hospitalised patients. Data from 17 332 adult hospitalised patients admitted to Sir Charles Gairdner Hospital, Perth, Western Australia, with a respiratory illness between 2012 and 2015 were linked with data containing reverse transcription polymerase chain reaction results for respiratory viruses including A/H1, A/H3, influenza B, human metapneumovirus, respiratory syncytial virus and parainfluenza. Of these, 1753 (10.1%) had test results. Multivariable regression analyses were conducted to compare the viruses for clinical outcomes including ICU admission, ventilation, pneumonia, length of stay and death. Patients with A/H1 were more likely to experience severe outcomes such as ICU admission (OR 2.5, 95% CI 1.2–5.5, P = 0.016), pneumonia (OR 3.0, 95% CI 1.6–5.7, P < 0.001) and lower risk of discharge from hospital (indicating longer lengths of hospitalisation; HR 0.64 95% CI 0.47–0.88, P = 0.005), than patients with A/H3. Patients with a non-influenza respiratory virus were less likely to experience severe clinical outcomes than patients with A/H1, however, had similar likelihood when compared to patients with A/H3. Patients hospitalised with A/H1 had higher odds of severe outcomes than patients with A/H3 or other respiratory viruses. Knowledge of circulating influenza strains is important for healthcare preparedness.

Social network characteristics of people who inject drugs (PWID) have previously been flagged as potential risk factors for HCV transmission such as increased injection frequency. To understand the role of the injecting network on injection frequency, we investigated how changes in an injecting network over time can modulate injecting risk behaviour. PWID were sourced from the Networks 2 Study, a longitudinal cohort study of PWID recruited from illicit drug street markets across Melbourne, Australia. Network-related correlates of injection frequency and the change in frequency over time were analysed using adjusted Cox Proportional Hazards and Generalised Estimating Equations modelling. Two-hundred and eighteen PWID followed up for a mean (s.d.) of 2.8 (1.7) years were included in the analysis. A greater number of injecting partners, network closeness centrality and eigenvector centrality over time were associated with an increased rate of infection frequency. Every additional injection drug partner was associated with an increase in monthly injection frequency. Similarly, increased network connectivity and centrality over time was also associated with an increase in injection frequency. This study observed that baseline network measures of connectivity and centrality may be associated with changes in injection frequency and, by extension, may predict subsequent HCV transmission risk. Longitudinal changes in network position were observed to correlate with changes in injection frequency, with PWID who migrate from the densely-connected network centre out to the less-connected periphery were associated with a decreased rate of injection frequency.

Evaluation of antimalarial efficacy is difficult because recurrent parasitaemia can be due to recrudescence or re-infection. PCR is used to differentiate between recrudescences and re-infections by comparing parasite allelic variants before and after treatment. However, PCR-corrected results are susceptible to misclassification: false positives, due to re-infection by the same variant present in the patient before treatment; and false negatives, due to variants that are present but too infrequent to be detected in the pre-treatment PCR, but are then detectable post-treatment. This paper aimed to explore factors affecting the probability of false positives and proposes a Monte Carlo uncertainty analysis to account for both types of misclassification. Higher levels of transmission intensity, increased multiplicity of infection, and limited allelic variation resulted in more false recrudescences. The uncertainty analysis exploits characteristics of study data to minimize bias in the estimate of efficacy and can be applied to areas of different transmission intensity.

Data on the impact of the recently recommended maternal pertussis vaccination are promising, but still insufficient to universalise this approach. We thus compared the epidemiological data prior to the implementation of this vaccination strategy in Argentina (2012) with the figures reported after 2012. During that 2010–2016 period, two outbreaks occurred, one in 2011 and another in 2016. In the former, the incidence was 6.9/100 000 inhabitants and the case-fatality rate 2.6%. Thereafter, a decline in incidence was detected until 2014. During 2015 and 2016 an increase in the incidence transpired, but this rise was fortunately not accompanied by one in the case fatality ratio. Indeed, in 2016 the case fatality ratio was the lowest (0.6%). Moreover, during the 2016 outbreak, the incidence (3.9/100 000 inhabitants) and the case severity detected in the most vulnerable population (infants 0–2 months) were both lower than those in 2011. Consistent with this pattern, in 2016, in the most populated province of Argentina (Buenos Aires), the case percentage with laboratory-positive results indicating a high number of symptoms (59.1% of the total cases) diminished compared with that detected in the 2011 outbreak without maternal immunisation (71.9%). Using the mathematical model of pertussis transmission we previously designed, we assessed the effect of vaccination during pregnancy on infant incidence. From comparisons between the epidemiological data made through calculations, emerged the possibility that vaccinating women during pregnancy would benefit the infants beyond age 2 months, specifically in the 2–12-month cohort.

Tularemia has sustained seroprevalence in Eurasia, with estimates as high as 15% in endemic regions. The purpose of this report is to characterise the current epidemiology of Francisella tularensis subspecies holarctica in Georgia. Three surveillance activities are summarised: (1) acute infections captured in Georgia's notifiable disease surveillance system, (2) infectious disease seroprevalence study of military volunteers, and (3) a study of seroprevalence and risk factors in endemic regions. Descriptive analyses of demographic, exposure and clinical factors were conducted for the surveillance studies; bivariate analyses were computed to identify risk factors of seropositivity using likelihood ratio χ2 tests or Fisher's exact tests. Of the 19 incident cases reported between 2014 and August 2017, 10 were confirmed and nine met the presumptive definition; the estimated annual incidence was 0.12/100 000. The first cases of tularemia in Western Georgia were reported. Seroprevalences of antibodies for F. tularensis were 2.0% for military volunteers and 5.0% for residents in endemic regions. Exposures correlated with seropositivity included work with hay and contact with multiple types of animals. Seroprevalence studies conducted periodically may enhance our understanding of tularemia in countries with dramatically underestimated incidence rates.

The assemblages of Giardia duodenalis in 25 children with and 25 children without diarrhoea and 24 adults with gastrointestinal symptoms in South India were determined. Polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) targeting the glutamate dehydrogenase (gdh), β-giardin and triosephosphate isomerase (tpi) genes was used. The tpi PCR was the most sensitive and detected G. duodenalis in all 74 microscopy-positive samples, while gdh and β-giardin PCR were positive in 62·2% and 56·8% of the samples. Assemblage B was predominant in both children and adults (82·4%) followed by assemblage AII (9·4%); assemblage AI was not detected. Infections with both assemblages A and B (detected by tpi PCR–RFLP) were seen exclusively in children and the mixed assemblage BIII and BIV (detected by gdh PCR–RFLP) was more common in children than adults (P=0·058).