Fifty-seven Salmonella Typhimurium strains isolated from poultry, swine and animal feed in Poland during the years 1979–1998 and 2000–2002 were analysed with conventional and molecular techniques. Antimicrobial resistance as well as multiresistance was found, respectively, in 80·1% and 56·1% of the isolates and most frequently among isolates from 2000–2002. Of several phage types noted, DT104 was prevalent among poultry, swine and feed isolates. DT104, U302 and non-typable strains had a multiple resistant profile (ACSSuT) due to the presence of class I integrons. Pulse-field gel electrophoresis of XbaI and BlnI digest showed high genomic similarity between the strains and confirmed clonal spread of S. Typhimurium infections. Plasmid profiling allowed further differentiation of the strains. We have, therefore, confirmed the appearance of S. Typhimurium DT104 showing genome integrated integron-mediated antimicrobial resistance in Poland. These findings are significant for public and animal health risks and document the dissemination of DT104 epidemic strains into new geographical regions.

To the Editor:

In a previous report [1], we described significant risks for hepatitis B (HBV) and hepatitis C (HCV) positivity associated with receipt of tattoos, particularly while incarcerated, among a street-recruited population of injection drug users (IDUs) in New Mexico, United States from 1995 to 1997. Another recent report in this Journal, based on a study conducted on prisoners in Australia, found tattooing in prison to be an independent risk for HCV [2]. Another report also described a strong association between tattoos and HCV, but found the strongest association to be with commercial tattooing venues [3]. That study found the risk associated with receipt of tattoos in prison elevated, but not statistically significant. That same report reviewed other articles and found a significant risk for HCV infection associated with tattoos in six out of eight studies that had data available. Further, a recent U.S. Centers for Disease Control and Prevention (CDC) document summarized the literature on risks for hepatitis infections in correctional settings and developed extensive control guidelines [4].

Measurements of the rate of ventilation were made on 312 occasions in thirty-one rooms in (a) a block of older flats, (b) a block of modern flats, (c) three villa residences, and (d) a modern university building.

The rate of air change was determined by liberating a quantity of coal gas into the room and measuring the rate of its subsequent disappearance by means of a katharometer.

The effects on natural ventilation of air gratings and flues were studied in unheated rooms in two blocks of flats. The effective orifices of the gratings were 10·5 sq. in. in the modern flats and 6 sq. in. in the older ones. With the air gratings or flues (if any) closed the rates of air change were 0·55 and 0·71 per hour respectively. With the air gratings open the air change was increased to 0·83 per hour in the modern flats and to 1·04 per hour in the older ones.

The flues in the modern flats in connexion with gas fires were 4 in. diameter pipes (cross-sectional area, 12·6 sq. in.); in the older flats the ordinary fire-places were connected to standard flues and the area of the register openings was 53 sq. in. When the flues were sealed, the air changes per hour in the modern and older flats were 0·84 and 0·72 respectively and when the flues were opened these rates of ventilation were increased to 1·17 and 2·06 air changes per hour. In nine rooms in three other houses the average ventilation rates with the flues closed and open were respectively 0·82 and 1·76 air changes per hour.

The ordinary chimney flue, even without a fire at its base, was an efficient ventilator, but the flue of smaller dimensions was far less effective.

With windows open almost any required amount of ventilation could be obtained, and the observations showed that even when windows are opened only slightly the ventilation is distinctly increased. Thus, in flueless rooms of the modern flats, with doors and windows closed, but with the air grating open, the ventilation amounted to 0·83 air changes per hour, but with one casement only open to a width of 3/8 in. it was increased to 1·79 air changes.

The effects of various factors on the rate of air change are discussed and illustrated. Of these, outside wind speed appears to have most influence. The evidence regarding the effect on ventilation of the difference in temperature between the room air and the outside air is very conflicting. In the present observations, when outside wind speed is taken into account, no definite effect of temperature difference on air change is seen. But the experiments were made in unheated rooms and the temperature difference rarely exceeded 10° F., and in the majority of cases was much less.

The various recommended standards of air supply are discussed. Although certain bye-laws require a fresh-air supply of 1000 cu. ft. per person per hour, it is probable that where there is no overcrowding, as in the normally occupied dwelling-room, a ventilation rate of not less than 600 cu. ft. per person per hour should be sufficient to prevent body odours from becoming apparent.

The results of this inquiry show that in closed, flueless rooms, the air supply is likely to be much below 600 cu. ft. per hour per occupant.

On account of the low ventilation rates observed in flueless rooms it is desirable that the question of the use of flueless gas heaters in such rooms be reconsidered.

The biological characters of eight strains of the Newcastle disease virus, isolated in different parts of the world between 1933 and 1951, have been studied and compared in detail.

Two types of the virus have been distinguished, one from the Newcastle disease prevalent in Europe and Australia, the other from that occurring in the United States of America.

Viruses of the first type are highly virulent, multiply rapidly and successively develop the properties of infectivity, haemagglutination and haemolysis. Their haemagglutination pattern is constant and wide; they profoundly modify human group O erythrocytes, and they are antigenically homogeneous.

Viruses of the second type are of weaker virulence. They grow at a slower rate in the allantoic cavity of the chick embryo, and the development of their characters is retarded; they have a reduced haemagglutination pattern and only a minimum capacity to modify human group O cells. Antigenically strains of the second type are homogeneous.

From haemagglutination inhibition and absorption studies it is concluded that major antigens are shared by both types, and that the first type possesses one or more antigens lacking in the second.

The highly virulent Canadian TWISS strain possesses the characters of the first type and an antigenic constitution with features of both types.

The significance of the results is discussed in relation to the ecology of Newcastle disease.

One of the most striking points in the pathology of Bacterial Dysentery is the fact that while the bacilli are found regularly in the mesenteric glands, they are not found in the spleen or other organs, and do not occur in the blood, urine, or milk. In this respect Lentz (p. 320) points out that the disease differs markedly from the septicaemic diseases, such as typhoid, and that it must be regarded as a local infection of the intestinal mucous membrane and corresponding lymphatic glands by the bacillus, the toxin alone passing into the circulation and giving rise to the typical clinical picture, which, as in the case of cholera, gives the impression of a severe poisoning or toxaemia.

West Nile virus (WNV) is a growing public health concern in Europe and there is a need to develop more efficient early detection systems. Nervous signs in horses are considered to be an early indicator of WNV and, using them in a syndromic surveillance system, might be relevant. In our study, we assessed whether or not data collected by the passive French surveillance system for the surveillance of equine diseases can be used routinely for the detection of WNV. We tested several pre-processing methods and detection algorithms based on regression. We evaluated system performances using simulated and authentic data and compared them to those of the surveillance system currently in place. Our results show that the current detection algorithm provided similar performances to those tested using simulated and real data. However, regression models can be easily and better adapted to surveillance objectives. The detection performances obtained were compatible with the early detection of WNV outbreaks in France (i.e. sensitivity 98%, specificity >94%, timeliness 2·5 weeks and around four false alarms per year) but further work is needed to determine the most suitable alarm threshold for WNV surveillance in France using cost-efficiency analysis.

Since the implementation of Streptococcus pneumoniae (SPn) conjugate vaccination (PCV), non-vaccine types have prevailed in invasive pneumococcal disease (IPD), and an increase in Staphylococcus aureus (SA) burden has been suggested. Here, we assess the epidemiology of SA and SPn nasal carriage in 620 children at day-care centres; 141 of these children had received 1–4 PCV7 doses. A higher vaccine dosage was associated with non-vaccine-type SPn carriage. Of all SPn isolates, 45% were PCV7 types, 1% were additional PCV10 types and 22% were the three additional PCV13 types. SA carriage was inversely associated with vaccine-type SPn carriage. SPn serotype 19A showed higher SA co-carriage rates compared to other SPn serotypes. PCV7 implementation does not prevent children from being part of the IPD-related SPn transmission chain. These results contribute to the monitoring of SA- and SPn-related disease and add to the debate on the current national vaccination policy that recently included a change from PCV7 to PCV10.

Between 2007–2008 and 2010–2012, 870 organ samples were collected from wild boars in 16 Transylvanian counties. Anaplasma phagocytophilum DNA was identified using a nested PCR protocol that amplifies a fragment of the 16S rRNA gene. Prevalence was compared between sampling periods and counties using Fisher's exact test. In total, 39 (4·48%) samples tested positive, with significantly higher values recorded in the second period, caused by an increased infection rate in boars from Sibiu county. Positive cases tended to concentrate in the central part of the country. During the second sampling period, A. phagocytophilum was detected in two additional counties, suggesting a spatial spreading of the pathogen. The results confirm that Transylvanian wild boars are naturally infected with A. phagocytophilum, thus raising awarness concerning a potential zoonotic cycle. This is the first study to evaluate spatial and temporal variations of A. phagocytophilum distribution in wild boar populations from Transylvania.

In vitro tests have been developed for the diagnosis of tuberculosis (TB) infection. The objective was to analyse latent TB infection in drug and alcohol abusers through two interferon-γ techniques. One hundred and thirty-nine patients were admitted between February 2006 and May 2007. Mean age was 39·8 years [31% HIV positive]. The enzyme immunoassay (EIA) and enzyme-linked immunospot (ELISPOT) interferon-γ assays were positive in 34% of patients with an agreement of 83% (κ=0·63). Tuberculin skin test (TST) was positive in 29% of patients and the agreement of TST with EIA and ELISPOT interferon-γ assays was 85% (κ=0·62) and 83% (κ=0·57), respectively. Almost 50% of patients with history of TB had a positive in vitro test. In conclusion, we observed a high prevalence of latent TB and good agreement between the new in vitro tests that otherwise may continue to be positive long after developing TB disease.

The role of the Eurasian badger (Meles meles) as a wildlife host has complicated the management of bovine tuberculosis (bTB) in cattle. Badger ranging behaviour has previously been found to be altered by culling of badgers and has been suggested to increase the transmission of bTB either among badgers or between badgers and cattle. In 2014, a five-year bTB intervention research project in a 100 km2 area in Northern Ireland was initiated involving selective removal of dual path platform (DPP) VetTB (immunoassay) test positive badgers and vaccination followed by release of DPP test negative badgers (‘Test and Vaccinate or Remove’). Home range sizes, based on position data obtained from global positioning system collared badgers, were compared between the first year of the project, where no DPP test positive badgers were removed, and follow-up years 2–4 when DPP test positive badgers were removed. A total of 105 individual badgers were followed over 21 200 collar tracking nights. Using multivariable analyses, neither annual nor monthly home ranges differed significantly in size between years, suggesting they were not significantly altered by the bTB intervention that was applied in the study area.

Over a 24 month period on six paediatric wards of different designs 169 cases of possible hospital-acquired respiratory virus infection were investigated. A variety of viruses was isolated from 82 cases, the most common being respiratory syncytial virus, influenza, parainfluenza, adenoviruses and rhinoviruses. A further 73 children developed respiratory symptoms between 3 and 300 days after admission but viruses were not demonstrable by the techniques used. These children were thought to have hospital-acquired infection nonetheless. Thirteen children were shown not to have acquired infection as the cause of their intercurrent illness. Most acquired infections occurred where toddlers were in cots in open wards. Children with trauma, including non-accidental injury, congenital malformations, mental retardation, failure to thrive or neoplasia were most likely to become infected. Almost 20 % of children suffered from croup or lower respiratory tract illness as a result of their acquired infection. The figure was 41 % if those less than 12 months old were considered alone. Most episodes settled quickly but in a few children investigations or surgery were delayed for a few days.

This paper describes the epidemiologically relevant events that took place in a dairy herd infected by Salmonella dublin. The evidence presented indicates that it may be possible to eliminate infection from the farm and that residual infection or persistent excretion are uncommon. In two animals infection persisted, in one instance in the tonsil and in the other in the gall bladder. In this latter case the infection remained from the neonatal period until adulthood. It is possible that both these animals are relevant in a more general context and are indicative of the source of infection in outbreaks in which the origin of infection cannot be deter-mined by more routine examinations.

The genetic and biochemical basis of ampicillin resistance amongst the aerobic Gram-negative commensal faecal flora of healthy volunteers in South Africa has been determined. Amongst 608 ampicillin resistant strains isolated from 320 of the participants, 158 were able to transfer their ampicillin resistant determinants into Escheriehia coli K-12 J62–2. Iso-electric focusing of the β-lactamases, extracted from the transconjugants, demonstrated that ampicillin resistance resulted from the presence of the TEM-1, TEM-2 and SHV-1 β-lactamases in 94·3%, 2·5% and 3·2% of isolates respectively. Endonuclease restriction digests of the plasmids isolated from the transconjugants showed that the β-lactamase genes were present on a wide variety of plasmid types; 101 distinct plasmid endonuclease restriction patterns were identified. Transferable ampicillin resistance was associated with resistance to other antibiotics at the following frequencies: trimethoprim (48·7 %), streptomycin (35·4 %), tetracycline (27·2%), spectinomycin (9·5%), chloramphenicol (3·2%) and gentamicin (1·3%). One antibiotic resistance pattern, ampicillin and trimethoprim. predominated (28%). In total. 77·9% of the plasmids conferred resistance to other antibiotics raising the possibility that use of any of these agents, not simply ampicillin, may contribute to the maintenance of resistance genes.

The question of the relationship of the virulent diphtheria bacillus to avirulent forms of similar morphology and fermentative properties has always attracted the interest of bacteriologists. Practically all careful observers agree that avirulent bacilli can never become virulent either in vivo or in vitro. It has been also the experience of most observers that no virulent strain can be made avirulent by laboratory methods. Crowell (1926) and Cowan (1927) have however reported that they had succeeded in isolating avirulent variants from a pure culture of a virulent strain. From the nature of Crowell's experiment, which only records one such change, it seems possible that he may have chanced on a true biological (i.e. uncontrolled) variation, but Cowan suggests that it might be possible to isolate with some degree of regularity “rough” avirulent colonies from virulent cultures. As Cowan points out the procedure is both lengthy and difficult. My own experiments in this direction have been entirely negative, although I have on many occasions tried to isolate avirulent variants from virulent cultures by colony selection and other methods. I have not even been successful with the cultures with which Miss Cowan worked and which she very kindly put at my disposal. Individual colonies of the Park 8 strain have been also tested on more than 700 occasions and have always proved fully virulent when pure. Passage both through a large variety of artificial media and through animals failed to engender avirulent variants.

The aim of this study was to describe the occurrence of shiga toxic genes (stx) in Norwegian sheep herds, and to identify herd management factors related to the occurrence of stx in herds. Faecal samples from 124 sheep-herds were collected at abattoirs in 1998. Pooled samples from lambs and from ewes were screened for stx by a PCR method directly on faeces. Of the 124 herds, 61 were positive for stx, giving an overall herd-prevalence of 49%. Twenty-one of the 61 positive herds were positive both in lamb and ewe samples, 24 only in lamb samples and 16 only in ewe samples. There was no difference in prevalence between regions. From the 21 herds positive both in lamb and ewe samples, stx encoding E. coli were detected in 18 herds using hydrophobic grid membrane filters and subsequent colony hybridization. Information about management factors was collected by telephone interviews. Having cattle at the same farm turned out to be a possible risk factor, with an Odds Ratio of 9·9 (CI 1·2 → ∞).

Ethnic disparities in chlamydia infections in The Netherlands were assessed, in order to compare two definitions of ethnicity: ethnicity based on country of birth and self-defined ethnicity. Chlamydia positivity in persons aged 16–29 years was investigated using data from the first round of the Chlamydia Screening Implementation (CSI, 2008–2009) and surveillance data from STI centres (2009). Logistic regression modelling showed that being an immigrant was associated with chlamydia positivity in both CSI [adjusted odds ratio (aOR) 2·3, 95% confidence interval (CI) 2·0–2·6] and STI centres (aOR 1·4, 95% CI 1·3–1·5). In both settings, 60% of immigrants defined themselves as Dutch. Despite the difference, classification by self-defined ethnicity resulted in similar associations between (non-Dutch) ethnicity and chlamydia positivity. However, ethnicity based on country of birth explained variation in chlamydia positivity better, and is objective and constant over time and therefore more useful for identifying young persons at higher risk for chlamydia infection.

Despite rapid urbanization and increasing affluence in Karachi, cases of cholera are frequent. We analysed computerized isolation data from the AKUH Clinical Microbiology Laboratory, Karachi, from 1990–6 to examine microbiological, temporal and demographic trends in Vibrio cholerae infections. During this period 888 strains of V. cholerae (566 V. cholerae serogroup O1, and 204 V. cholerae serogroup O139) were isolated from specimens from 886 patients; 214/464 were adult inpatients, and 250/464 paediatric inpatients, the remaining 422 outpatients. Isolations peaked between June and August. Overlapping epidemics occurred in 1993 and 1994 of serogroup O1 (May to August), and serogroup O139 (August to October). All ages and social and economic strata were affected. Forty-four percent of all isolates were from children under the age of 5 years. The mean age of all patients with serogroup O1 infections was 19·6 years (±0·9) compared with 36·7 (±1·7) for serogroup O139 infections (P<0·0001, t test). More than a quarter (27%) of all serogroup O1 isolates were from babies under 2 years of age. One patient had a serogroup O1 infection followed by a serogroup O139 infection 1 year later. Another patient was infected with serogroup O1 strains 5 years apart. Emergence of resistant strains was observed, but by 1996 serogroup O139 had disappeared. An aquatic organism, cholera nevertheless continues to take its toll in this city of 11 million situated in a desert.

Japan experienced dengue outbreaks vectored by Aedes albopictus during the Second World War. The probable vector density that caused the largest dengue outbreak in Nagasaki in 1942 was estimated using a mathematical simulation model. The estimated vector density was 15·0–558·0 per person when various assumptions of uncertain parameters were applied, such as proportion of symptomatic cases, vector mortality, and human biting rate of A. albopictus. When the most favourable disease spread conditions, such as a combination of the exclusive human biting rate and the longest vector survival were assumed, the vector density was 15–25 mosquitoes per person. Unusually high vector density due to wartime practices, and the traditional Japanese lifestyle were presumably responsible for the earlier dengue outbreak. If an outbreak occurs in present-day Japan, it is unlikely to spread as much as the previous one, as environmental conditions and human behaviour have changed in a protective manner.

A longitudinal study in England and Wales of two dairy, five beef-fattener and three beef-suckler herds was carried out to identify risk factors for young cattle excreting verocytotoxin-producing Escherichia coli O157 (VTEC O157). A total of 1383 cattle, selected into cohorts at 0–24 months were sampled between March 2000 and February 2001. Mixed-effects logistic regression was employed to identify significant associations between VTEC O157 isolation from rectal faecal samples and explanatory factors (P < 0·001 unless shown). The results revealed a positive association with feeding root crops and a negative association with animals fed silage, milk (P = 0·001) or grain (P = 0·027). Cattle in suckler herds (P = 0·001) and those changing group between sampling visits were identified as negatively associated with VTEC O157 presence. The recovery of VTEC O157 varied throughout the year. However, the winter period from December to February was a risk factor in the multivariable analysis. Cattle in pens were 4·7 times more likely to shed VTEC O157 than those group-housed or at pasture. VTEC O157 detected in pooled environmental faecal pats and biofilm of the water supply within a group's enclosure were positively associated with an animal's VTEC O157 status in the multivariable logistic regression, as was detection of VTEC O157 in the pooled faecal pats at the previous visit.

The characteristics of norovirus outbreaks in children (0–5 years) in childcare centres in Victoria, Australia (2012–2015) were examined. The three most common open reading frame (ORF) 2 genotypes in childcare centre outbreaks were GII.4 (42%), GII.6 (21%) and GII.3 (14%); the remaining genotypes (GI.2, GI.3, GI.4, GI.8, GI.13, GII.1, GII.2, GII.7 and GII.13) each made up <10%. The GII.4 genotype was the only norovirus genotype seen in all 4 years of the study and was the most common genotype in 2012–2014 but in 2015 the most common genotype was GII.2. The GII.4 genotype was more common in children 0–2 years, whereas GII.2 and GII.7 were more common in children 4–5 years. ORF 1/ORF 2 recombinant forms identified were GII.P4_NewOrleans_2009/GII.4_Sydney_2012, GII.P12/GII.3, GII.Pb (GII.21)/GII.3, GII.Pe/GII.2, GII.Pe/GII.4_Sydney_2012 and GII.Pg/GII.1. The findings indicate that norovirus genotype prevalence patterns in children were influenced by the age of the children and the year in which the analysis was carried out. The majority of norovirus infections (84%) occurred after the first year of life so that vaccination before the age of one would appear to be the most efficacious.