The present investigation deals with the routine bacteriological examination of 525 samples of water, 265 of which contained lactose fermenting bacilli; 1441 strains were isolated and various differential tests were used in the classification of these organisms.

All the strains were tested in dextrose phosphate culture for the methyl red and the Voges and Proskauer reactions, and although most of them gave normal results (M.R. + V.P. 0 or M.R. 0 V.P. +), there were 25 strains, 1·73 per cent., which gave either double positive or double negative reactions. Similar cases have already been discussed in an earlier portion of this paper, and they leave no doubt that there are types which may vary from the normal as far as the methyl red and the Voges and Proskauer reactions are concerned. At the same time these abnormal types are not sufficiently numerous to make any real practical difficulties in the use of these tests for routine purposes.

The Koser test, considered by many bacteriologists to be of great differential value, was found to give imperfect correlation with the other reactions.

1395 strains were isolated which could be classified in the B. coli group as a result of the production of acid and gas in lactose, the clotting of milk, and the non-liquefaction of gelatine, but when the methyl red and the Voges and Proskauer results were considered it was found that nearly 11 per cent. of these strains were of the B. lactis aerogenes type, and were therefore of no value as indicators of faecal pollution.

The indol reactions were somewhat variable. Among 1244 strains of the B. coli type (M.R. + V.P. 0), more than 10 per cent. failed to produce indol; while among 151 strains of the B. lactis aerogenes type (M.R. 0 V.P. +), nearly 51 per cent. were indol producers. Preliminary extraction with ether was carried out with 448 of these strains before Böhme's reagent was added. With this technique it was found that among 400 methyl red positive types there were 87 strains (22 per cent.) which produced no indol, and among 48 methyl red negative strains there were 12 (25 per cent.) which gave the reaction. Chen and Rettger (1920) were unable to establish any definite correlation between the indol test and the other reactions.

When the sample results were studied, it was found that although 262 waters contained organisms which were included in the B. coli group on the basis of the lactose, milk and gelatine tests, nearly 6 per cent. of these samples contained only organisms which gave a methyl red negative, Voges and Proskauer positive reaction, and were probably associated with pollution from soil washings rather than contamination from faecal sources. This means that the application of the methyl red and Voges and Proskauer reaction does make a considerable practical difference in the interpretation of results in the bacteriological examination of water.

More detailed examination as regards the fermentation of the various carbohydrates is useful for purposes of classification, but is of no significance, in the light of our present knowledge, in assessing the probability of excretal pollution.

It is suggested that, in considering the results of a bacteriological examination of water, organisms should be regarded as significant which are of typical morphology and staining reaction, produce acid and gas in lactose, fail to liquefy gelatine, clot milk, and give a positive methyl red and a negative Voges and Proskauer reaction. The production of indol in a medium containing peptone may be added as an extra test if desired, but the available evidence does not suggest that failure to produce indol is a sufficient basis for the exclusion of an otherwise typical bacillus from the B. coli group.

My thanks are due to Dr G. D. Dawson, in conjunction with whom the present investigation was started; and also to Prof. W. W. C. Topley whose interest throughout the course of the research was made manifest by his helpful advice and criticism.

Currently no national guidelines exist for the management of scabies outbreaks in residential or nursing care homes for the elderly in the United Kingdom. In this setting, diagnosis and treatment of scabies outbreaks is often delayed and optimal drug treatment, environmental control measures and even outcome measures are unclear. We undertook a systematic review to establish the efficacy of outbreak management interventions and determine evidence-based recommendations. Four electronic databases were searched for relevant studies, which were assessed using a quality assessment tool drawing on STROBE guidelines to describe the quality of observational data. Nineteen outbreak reports were identified, describing both drug treatment and environmental management measures. The quality of data was poor; none reported all outcome measures and only four described symptom relief measures. We were unable to make definitive evidence-based recommendations. We draw on the results to propose a framework for data collection in future observational studies of scabies outbreaks. While high-quality randomised controlled trials are needed to determine optimal drug treatment, evidence on environmental measures will need augmentation through other literature studies. The quality assessment tool designed is a useful resource for reporting of outcome measures including patient-reported measures in future outbreaks.

Provision of high-quality care and ensuring retention of children on antiretroviral therapy (ART) are essential to reduce human immunodeficiency virus (HIV)-associated morbidity and mortality. Virological non-suppression (≥1000 viral copies/ml) is an indication of suboptimal HIV care and support. This retrospective cohort study included ART-naïve children who initiated first-line ART between July 2015 and August 2017 in Johannesburg and rural Mopani district. Of 2739 children started on ART, 29.5% (807/2739) were lost to care at the point of analysis in August 2018. Among retained children, overall virological non-suppression was 30.2% (469/1554). Virological non-suppression was associated with higher loss to care 30.3% (229/755) compared with suppressed children (9.7%, 136/1399, P < 0.001). Receiving treatment in Mopani was associated with virological non-suppression in children under 5 years (adjusted odds ratio (aOR) 1.7 (95% confidence interval (CI) 1.1–2.4), 5–9 years (aOR 1.8 (1.1–3.0)) and 10–14 years (aOR 1.9 (1.2–2.8)). Virological non-suppression was associated with lower CD4 count in children 5–9 years (aOR 2.1 (1.1–4.1)) and 10–14 years (aOR 2.1 (1.2–3.8)). Additional factors included a shorter time on ART (<5 years aOR 1.8–3.7 (1.3–8.2)), and male gender (5–9 years, aOR1.5 (1.01–2.3)), and receiving cotrimoxazole prophylaxis (10–14 years aOR 2.0 (1.2–3.6)). In conclusion, virological non-suppression is a factor of subsequent programme loss in both regions, and factors affecting the quality of care need to be addressed to achieve the third UNAIDS 90 in paediatric HIV.

Q fever is a notifiable disease in Germany. The majority of the reported cases are related to outbreaks. The objective of our study was to evaluate the general role of Q fever in community-acquired pneumonia (CAP). We investigated respiratory samples and sera from 255 patients with CAP, who were enrolled into a CAPNETZ cohort in summer 2005. Altogether, our data showed a significant prevalence of Q fever as CAP (3·5%). If a patient's condition leads to a diagnostic test for Chlamydophila sp., Mycoplasma sp. or Legionella sp., then a Q fever diagnostic test should also be included. In particular, ELISA as a first diagnostic step is easy to perform. PCR should be performed at an early stage of the disease if no antibodies are detectable. Because of our highly promising findings we suggest performing PCR in respiratory samples.

A scheme is described for the identification of enteroviruses in tissue culture by neutralization with composite antiserum pools. The method for making these pools is given. Antisera to twenty-seven enteroviruses were included in the pools which were used to examine 115 viruses consisting of ninety-eight recently isolated viruses and seventeen prototype strains. The results indicate that this scheme provides a useful screening method for identifying enteroviruses. It has proved to be practicable, time saving and very economical in tissue culture.

We are grateful to Dr C. M. P. Bradstreet who made available some of the rabbit antisera.

The pandemic of coronavirus disease 2019 (COVID-19) has posed serious challenges. It is vitally important to further clarify the epidemiological characteristics of the COVID-19 outbreak for future study and prevention and control measures. Epidemiological characteristics and spatial−temporal analysis were performed based on COVID-19 cases from 21 January 2020 to 1 March 2020 in Shandong Province, and close contacts were traced to construct transmission chains. A total of 758 laboratory-confirmed cases were reported in Shandong. The sex ratio was 1.27: 1 (M: F) and the median age was 42 (interquartile range: 32–55). The high-risk clusters were identified in the central, eastern and southern regions of Shandong from 25 January 2020 to 10 February 2020. We rebuilt 54 transmission chains involving 209 cases, of which 52.2% were family clusters, and three widespread infection chains were elaborated, occurring in Jining, Zaozhuang and Liaocheng, respectively. The geographical and temporal disparity may alert public health agencies to implement specific measures in regions with different risk, and should attach importance on how to avoid household and community transmission.

Pulsed-xenon-ultraviolet light (PX-UVL) is increasingly used as a supplemental disinfection method in healthcare settings. We undertook a systematic search of the literature through several databases and conducted a meta-analysis to evaluate the efficacy of PX-UVL in reducing healthcare-associated infections. Eleven studies were included in the systematic review and nine in the meta-analysis. Pooled analysis of seven studies with before-after data indicated a statistically significant reduction of Clostridium difficile infection (CDI) rates with the use of the PX-UVL (incidence rate ratio (IRR): 0.73, 95% CI 0.57–0.94, I2 = 72%, P = 0.01), and four studies reported a reduction of risk of methicillin-resistant Staphylococcus aureus (MRSA) infections (IRR: 0.79, 95% CI 0.64–0.98, I2 = 35%, P = 0.03). However, a further four trials found no significant reduction in vancomycin-resistant enterococci (VRE) infection rates (IRR: 0.80, 95% CI 0.63–1.01, I2 = 60%, P = 0.06). The results for CDI and MRSA proved unstable on sensitivity analysis. Meta-regression analysis did not demonstrate any influence of study duration or intervention duration on CDI rates. We conclude that the use of PX-UVL, in addition to standard disinfection protocols, may help to reduce the incidence of CDI and MRSA but not VRE infection rates. However, the quality of evidence is not high, with unstable results and wide confidence intervals, and further high-quality studies are required to supplement the current evidence.

Unidentified open-air factors (OAFs) found to be adverse to the survival of microorganisms suspended on microthreads were investigated for their effect on realistic aerosols of Francisella tularensis in an open-air environment. This organism was chosen because it is probably the most infectious organism known to be capable of infecting both animals and man via the respiratory route, hence its potential use as a bioterrorist agent. A direct correlation was found between an open-air adverse effect on viability and virulence of airborne particles of <3 μm via the respiratory route in guinea pigs. One viable organism was sufficient to initiate an infection that resulted in a fatal tularaemia infection. The lethal effect of OAFs on F. tularensis was found to vary from day to day and was related to the source of the air in the UK. The adverse effect on viability was associated with an inverse effect according to the size of the airborne particle.

A Q fever outbreak was declared in February 2016 in a company that manufactures hoists and chains and therefore with no apparent occupational-associated risk. Coxiella burnetii infection was diagnosed by serology in eight of the 29 workers of the company; seven of them had fever or flu-like signs and five had pneumonia, one requiring hospitalisation. A further case of C. burnetii pneumonia was diagnosed in a local resident. Real-time PCR (RTi–PCR) showed a widespread distribution of C. burnetii DNA in dust samples collected from the plant facilities, thus confirming the exposure of workers to the infection inside the factory. Epidemiological investigations identified a goat flock with high C. burnetii seroprevalence and active shedding which was owned and managed by one of the workers of the company as possible source of infection. Genotyping by multispacer sequence typing (MST) and a 10-loci single-nucleotide polymorphism (SNP) discrimination using RTi–PCR identified the same genotype (MST18 and SNP type 8, respectively) in the farm and the factory. These results confirmed the link between the goat farm and the outbreak and allowed the identification of the source of infection. The circumstances and possible vehicles for the bacteria entering the factory are discussed.

Information is lacking in Canada on the frequency of exposures of healthy people to enteric pathogen sources (i.e. water, food, animal contact) at the community level. This information is critical to develop more robust risk assessments and prioritize control measures. A 12-month-long cross-sectional telephone survey of 1200 healthy individuals in a sentinel community was performed. Survey respondents were divided into three recall period groups (3, 7, 14 days). The occurrence of 46 exposures (including water, animal contact, environmental contact and high-risk foods) was assessed per recall period. Effect of age, gender, and season on exposures was modelled and frequencies of exposure were extrapolated. Thirty-five exposures had similar occurrences across recall periods. Age was significant for 23 exposures, season for 18, and gender for three. Exposures that vary by age and season (i.e. bottled water, swimming, etc.) warrant consideration when investigating and analysing cases of enteric illness.

The distribution of plasmids was studied in a representative collection of salmonella strains which comprised 98 Salmonella typhimurium and 96 other serotypes. Plasmids were detected in 72% of strains (mean 1·3 plasmids/strain) and individual strains harboured between 0 and 7 plasmids. They were more common among S. typhimurium than other serotypes (incidence 92 and 53%; mean 1·9 and 0·8 plasmids/strain respectively). Although a higher proportion of S. typhimurium (33%) were antibiotic-resistant compared to other serotypes (14%) the evidence presented indicated that R-plasmids were not responsible for the difference observed in the number and distribution of plasmids in these strains. These results were discussed in comparison with similar studies of Escherichia coli and other enteric genera.

Aerosol infection (AI) of Porton outbreak mice with Listeria species, exhibiting varying degrees of virulence, was compared with gastric intubation (GI) on the basis of numbers of deaths. 50% lethal dose (LD50) and pattern of listerial infection. The AI route appeared to be more sensitive, efficient and consistent than GI in that it required 105 fewer micro-organisms to obtain infection and death then ensued within 4 days, with GI deaths usually occurring on day 7. All the virulent strains tested caused 100% mortality by AI, while virulent and avirulent strains were indistinguishable by GI. Bacterial counts in the livers and spleens of infected mice were consistent with the relative virulence of the infectious agent using AI but not in GI mice. There were higher numbers of micro-organisms and more widespread lesions in the organs of AI mice than in GI. Results indicate that AI is an accurate in vivo indicator of virulence in listeria and using AI, bacterial counts in the liver and spleen could replace LD50 tests, thereby reducing the number of animals required for in vivo virulence testing.

Human immunodeficiency virus type 1 (HIV-1) epidemiology among residents of a rural agricultural plantation in Kericho, Kenya was studied. HIV-1 prevalence was 14·3%, and was higher among women (19·1%) than men (11·3%). Risk factors associated with HIV-1 for men were age (⩾25 years), marital history (one or more marriages), age difference from current spouse (⩾5 years), Luo ethnicity, sexually transmitted infection (STI) symptoms in the past 6 months, circumcision (protective), and sexual activity (⩾7 years). Among women, risk factors associated with HIV-1 were age (25–29 years, ⩾35 years), marital history (one or more marriages), age difference from current spouse (⩾10 years), Luo ethnicity, STI symptoms in the past 6 months, and a STI history in the past 5 years. Most participants (96%) expressed a willingness to participate in a future HIV vaccine study. These findings will facilitate targeted intervention and prevention measures for HIV-1 infection in Kericho.

Five large outbreaks of food poisoning are described in which clinical, epidemiological or laboratory data indicated Clostridium perfringens as the causative organism. The foodstuff common to all incidents was boiled salmon served cold as an hors d'oeuvre. In all cases the fish had been subject to a long period of cooling or storage between boiling and consumption. It is thought that multiplication of the organism occurred during this time.

Recommendations are made for the avoidance of further similar incidents.

Serotyping, subtyping and genotyping are important tools for epidemiological studies of group B streptococci (GBS). We investigated the genotype distribution of 353 GBS isolates originating from vaginal or rectal carriage to identify capsular serotypes and subtypes based on the surface protein genes of the alpha-like protein (Alp) family. GBS were recovered from 30% of 1176 pregnant women during the period 2007–2009, with a predominance of capsular genotypes III (35%), Ia (20%), V (17%), II (15%), Ib (8%) and IV (5%). The most common Alp gene was epsilon (26%), followed by rib (22%), alp2 (21%), bca (17%) and alp3 (14%). Several protein genes were significantly associated (G2=249·635, P<0·0001) with particular serotypes: epsilon with Ia, Ib, IV; bca with Ib, II; rib with II, III; alp3 with V; alp2 with III. High genetic diversity within GBS strains was observed using DNA macrorestriction. Serotypes Ib, II and III demonstrated the greatest genetic heterogeneity and serotype V the lowest heterogeneity (relative frequency coefficient ⩾0·03 vs. −0·46, respectively). Macrolide-resistant strains with serotype V and alp3 gene, showed higher uniformity in genetic profile. The distribution of serotypes and surface proteins of GBS strains are necessary data to inform the design and formulation of new GBS vaccines for use in Poland and other countries.

Classification, by agglutinogens, of 634 isolates of Bordetella pertussis collected from 1941 to 1968 in Great Britain demonstrated that a change from a predominantly 1,2,0,4 serotype (75% of those examined during 1941–4) to a predominantly 1,0,3,0 serotype (73% of those examined during 1966–8) occurred sometime after 1953. Furthermore, evidence from the examination of isolates collected between 1941 and 1953 suggests that the change may have been gradual. Isolates of serotype 1,2,3,4 made up 20–30% of the total of our cross-country selection for the periods 1941–4, 1946–9, 1950–3 and 1966–8, but over shorter periods in individual areas the percentage varied from negligible to as high as half of those isolated. Results from other countries show a similar drift towards a 1,0,3 serotype but more often from a 1,2,3 than from 1,2,0 serotype.

The value, in epidemiological studies, of extended information obtained by monospecific typing sera to all six, rather than only two or three agglutinogens, and confirmation of the results by agglutinin production is demonstrated: for instance not all 1,0,3 isolates were identical.

Campylobacters isolated from human, animal and environmental sources during the investigation of a milk-borne outbreak, an incident involving goats' milk and an outbreak associated with puppies were serotyped using the Penner and Lior schemes and biotyped using the Preston scheme. Application of these three methods to the incident strains demonstrated that heterogenicity amongst similar strains exists. This study has confirmed the need to use at least two typing methods when investigating epidemiologically-related strains and we suggest that a combination of a serotyping scheme and an extended biotyping scheme is the most useful.

Rift Valley fever virus (RVFV) is an emerging pathogen of major concern throughout Africa and the Arabian Peninsula, affecting both livestock and humans. In the past recurrent epidemics were reported in Mauritania and studies focused on the analysis of samples from affected populations during acute outbreaks. To verify characteristics and presence of RVFV during non-epidemic periods we implemented a multi-stage serological and molecular analysis. Serum samples of small ruminants, cattle and camels were obtained from Mauritania during an inter-epidemic period in 2012–2013. This paper presents a comparative analysis of potential variations and shifts of antibody presence and the capability of inter-epidemic infections in Mauritanian livestock. We observed distinct serological differences between tested species (seroprevalence: small ruminants 3·8%, cattle 15·4%, camels 32·0%). In one single bovine from Nouakchott, a recent RVF infection could be identified by the simultaneous detection of IgM antibodies and viral RNA. This study indicates the occurrence of a low-level enzootic RVFV circulation in livestock in Mauritania. Moreover, results indicate that small ruminants can preferably act as sentinels for RVF surveillance.

Ventilation of vessels varying widely in size was found to preserve the toxic effect of open-air factor(s). There was a correlation between the minimum rates of ventilation required and the ratios of the surface area of the vessels to their volumes. The data obtained allowed an estimate to be made of the diffusion coefficient of open-air factor(s) and gave an indication that the molecular weight range of the open air factor(s) was from 50 to 150.

High-risk human papillomaviruses (HPVs) are highly prevalent worldwide, and HPV genotype distribution varies regionally. Molecular surveys of HPVs are important for effective HPV control and prevention. Fifteen high-risk HPV strains (16, 18, 31, 33, 35, 39, 45, 51, 52, 53, 56, 58, 59, 66, 68) and six low-risk HPV strains (HPV6, 11, 42, 43, 44, CP8304) were detected by cervical cytology from 10 501 subjects. High-risk HPVs, low-risk HPVs, and both high- and low-risk HPVs were detected in 14·5%, 2·8%, and 2·4% of cases, respectively. Of 1782 subjects with high-risk HPV infection, 75·5%, 18·1%, and 6·4% were infected with one, two, and ⩾3 strains of high-risk HPVs, respectively. HPV52, HPV16, and HPV58 were the top three most dominant high-risk HPV genotypes in our population with positivity rates of 23·0%, 17·7% and 16·9%, respectively. Multiple infection was common, with significantly higher co-infection rates of HPV58/HPV33 (12·9%) and HPV58/HPV52 (11·3%). Further data comparisons showed that HPV genotype distribution varied markedly between domestic and international regions. In conclusion, a monolithic vaccination strategy is obviously impractical, and regional HPV surveillance is essential to optimize current HPV control and prevention.