When samples of domestic sewage are treated with doses of chlorine lower than the chlorine demand bactericidal action depends not only on the proportion of the demand satisfied but also on the absolute size of the dose. With doses just sufficiently large to leave residual chlorine detectable by o-tolidine, reduction in the plate count of bacteria after contact for 15 min. ranged in various tests from 96·2 to 98·7%.

With domestic sewage reduction in bacterial count after addition of chlorine is followed, after an interval, by aftergrowth of survivors which rapidly brings the population to its original level or higher. For this interval to be prolonged the initial concentration of chlorine must be considerably greater than the chlorine demand. This accords with the fact that the rapid reaction of chlorine with constituents of the sewage, which occurs in the first few minutes, is followed by a slower absorption which takes place over a prolonged period, so that the initial bactericidal action of residual chlorine tends to be lost after a time. For many purposes the effectiveness of chlorination should be judged not only by the percentage of bacteria destroyed after a short period of contact but also by the interval which elapses before aftergrowth becomes appreciable.

In samples of sewage treated with doses of chlorine sufficient to destroy the protozoa, surviving bacteria eventually reached a level of population much higher than that of the untreated sewage. The majority of such bacteria were found to be Gram-negative, non-sporing rods, which included strains of Proteus and of Pseudomonas pyocyanea. Tests with a pure culture of a species of Proteus showed that the organisms surviving chlorination are not intrinsically capable of reaching a higher population than the parent culture.

When sewage contains small quantities of gas liquor or thiocyanate the bactericidal action of doses of chlorine lower than the demand is much more prolonged than the action of comparable doses in domestic sewage, owing to the formation of cyanogen chloride.

Comparative tests of the action of chlorine and of cyanogen chloride on pure cultures of Bacterium coli in peptone water and on the mixed flora of sewage showed that the bactericidal effect of cyanogen chloride was more persistent than that of a comparable dose of chlorine. With sewage and with some brands of peptone the immediate effect of the chlorine, on the other hand, was often considerable.

In this study, we describe a contained measles outbreak in a London prison, the second such outbreak in a custodial setting. Once vaccination commenced, just under a third of eligible prisoners were immunised due to a low uptake of the vaccine. We conducted a root-cause analysis in order to identify factors which may have prevented or altered the course of the outbreak. Our analysis revealed that many of the factors identified are those that cannot be easily changed. It is unlikely that mass vaccination at the time, even in the absence of some of the more easily rectifiable issues, could have fully avoided further cases in the event of a mass outbreak. Both measles outbreaks in a custodial setting started with a member of staff and immunisation status of the staff were largely unknown. We argue that mass vaccination following an outbreak in a prison is unlikely to fully prevent a mass outbreak, and that implementing opt-out testing, empirical vaccination and insisting on full immunisation of staff are most likely to both prevent and contain outbreaks in the future.

Canine influenza virus (CIV) is an emerging pathogen that causes acute respiratory disease in dogs. The aim of this study was to investigate the pathogenicity of A/canine/Jiangsu/06/2010 (H3N2) virus isolated in China. Nine dogs were inoculated intranasally with 107·95 of 50% egg infectious dose (EID50) of the virus. The onset of clinical signs and virus shedding was observed on day 1 post-infection (p.i.). The peak clinical score occurred between days 4 and 6 p.i. The experimentally infected dogs were found to shed virus not only via the respiratory tract but also via the digestive tract. Viral RNA could be detected in multiple organs including the trachea, lung, liver, spleen, kidney, brain and duodenum. All the sampled organs from infected dogs showed significant lesions and viral antigen staining. The results differed from those reporting using previous CIV strains; the Chinese isolate could induce extrapulmonary infection and cause extensive lesions in dogs.

Children are important transmitters of infection. Within schools they encounter large numbers of contacts and infections can spread easily causing outbreaks. However, not all schools are affected equally. We conducted a retrospective analysis of school outbreaks to identify factors associated with the risk of gastroenteritis, influenza, rash or other outbreaks. Data on reported school outbreaks in England were obtained from Public Health England and linked with data from the Department for Education and the Office for Standards in Education, Children's Services and Skills (Ofsted). Primary and all-through schools were found to be at increased risk of outbreaks, compared with secondary schools (odds ratio (OR) 5.82, 95% confidence interval (CI) 4.50–7.58 and OR 4.66, 95% CI 3.27–6.61, respectively). School size was also significantly associated with the risk of outbreaks, with higher odds associated with larger schools. Attack rates were higher in gastroenteritis and influenza outbreaks, with lower attack rates associated with rashes (relative risk 0.17, 95% CI 0.15–0.20). Deprivation and Ofsted rating were not associated with either outbreak occurrence or the subsequent attack rate. This study identifies primary and all-through schools as key settings for health protection interventions. Public health teams need to work closely with these schools to encourage early identification and reporting of outbreaks.

Although vaccines have become available, emergence and rapid transmission of new variants have added new paradigm in the coronavirus disease-2019 (COVID-19) pandemic. Weather, population and host immunity have been detected as the regulatory elements of COVID-19. This study aims to investigate the effects of weather, population and host factors on the outcome of COVID-19 and mutation frequency in Japan. Data were collected during January 2020 to February 2021. About 92% isolates were form GR clades. Variants 501Y.V1 (53%) and 452R.V1 (24%) were most prevalent in Japan. The strongest correlation was detected between fatalities and population density (rs = 0.81) followed by total population (rs = 0.72). Relative humidity had the highest correlation (rs = −0.71) with the case fatality rate. Cluster mutations namely N501Y (45%), E484K (30%), N439K (16%), K417N (6%) and T478I (3%) at spike protein have increased during January to February 2021. Above 90% fatality was detected in patients aged >60 years. The ratio of male to female patients of COVID-19 was 1.35:1. This study will help to understand the seasonality of COVID-19 and impact of weather on the outcome which will add knowledge to reduce the health burden of COVID-19 by the international organisations and policy makers.

Otitis externa is the inflammation of the external auditory canal. The disease is common and shows a seasonal variation with a greater incidence in warmer months. Pseudomonas aeruginosa is a common pathogen in otitis externa and in this retrospective study, we show a corresponding seasonal variation in the proportional incidence of P. aeruginosa isolates from otitis externa in South East England. In total 7770 patients were diagnosed with otitis externa over a period of 9 years from January 2008 to December 2016. P. aeruginosa was isolated from 2802 patients (proportional incidence of 36%). Incidence was higher in the months of August, September and October and in patients between 5 and 15 years of age. We postulate a combination of increased contact with water during warm weather in the holiday season and increased rainfall in the preceding season as a putative mechanism for the seasonal trends.

In a cross-sectional survey of 226 HIV-infected men, we examined the occurrence of diarrhoea and its relationship to drinking water consumption patterns, risk behaviours, immune status and medication use. Diarrhoea was reported by 47% of the respondents. Neither drinking boiled nor filtered water was significantly associated with diarrhoea (OR = 0·5 [0·2, 1·6], 1·2 [0·6, 2·5] respectively), whereas those that drank bottled water were at risk for diarrhoea (OR = 3·0 [1·1, 7·8]). Overall, 47% always or often used at least one water treatment. Of the 37% who were very concerned about drinking water, 62% had diarrhoea, 70% always or often used at least one water treatment. An increase in CD4 count was protective only for those with a low risk of diarrhoea associated with medication (OR = 0·6 [0·5, 0·9]). A 30% attributable risk to diarrhoea was estimated for those with high medication risk compared to those with low medication risk. The significant association between concern with drinking water and diarrhoea as well as between concern with drinking water and water treatment suggests awareness that drinking water is a potential transmission pathway for diarrhoeal disease. At the same time we found that a significant portion of diarrhoea was associated with other sources not related to drinking water such as medication usage.

The following paper investigates the prevalence and characteristics of asymptomatic norovirus infection in the population living around oyster farm sites. Two consecutive surveys were conducted from January 2014 to December 2014 and 4549 stool samples were screened during the same time period. The total asymptomatic infection rate was 4.04% (184/4549). Norovirus infection rate was 5.20% in oyster farming population which was significantly higher compared with non-farming population where the infection rate was 3.65% (χ2 = 5.49, P < 0.05). A total of 184 NoV positive samples were identified by real time-quantitative polymerase chain reaction (RT-qPCR) and semi-nested RT-PCR and 136 sequences were obtained. The sequences were clustered into 14 genotypes. GI strains were clustered into six genotypes, including GI.2, GI.3, GI.5, GI.6, GI.8 and GI.9; while GII strains were clustered into GII.2, GII.3, GII.4, GII.5, GII.6, GII.8 and GII.13. GI.9 and GII.17 were the predominant and most prevalent genotypes, respectively. The GII.17 genotype replaced GII.4 becoming the dominant genotype in the oyster farming area in 2014. To sum up, long-term monitoring of asymptomatic infection is crucial for the detection of new variant strains and for identifying outbreaks during the early stage.

Although Giardia, the aetiological agent of giardiasis, is one of the most prevalent intestinal parasitic infections world-wide, for industrialised countries, it is mainly appreciated as an imported disease with the minimal local transmission. However, the current evidence challenges this perception; Giardia has relevance beyond the high prevalence areas. This infection may be asymptomatic or cause gastrointestinal complains and long-term sequelae, including irritable bowel syndrome, chronic fatigue and impaired child growth and cognitive development. Its detection and diagnosis present a challenge to physicians who may not be familiar with this infection. To improve interventions to control this parasitosis, it is necessary to maintain a high index of suspicion and remain vigilant in finding cases at risk for infection. A better understanding of the characteristics of populations importing infections alongside improved methods to reliably classify infections as imported or acquired locally will help to ensure early and accurate diagnosis. The evidence shows that public health problems like giardiasis are global issues that need to be addressed collectively by both high and low prevalence countries.

This study set out to identify and analyse trends and seasonal variations of monthly global reported cases of the Middle East respiratory syndrome coronavirus (MERS-CoV). It also made a prediction based on the reported and extrapolated into the future by forecasting the trend. Finally, the study assessed contributions of various risk factors in the reported cases. The motivation for this study is that MERS-CoV remains among the list of blueprint priority and potential pandemic diseases globally. Yet, there is a paucity of empirical literature examining trends and seasonality as the available evidence is generally descriptive and anecdotal. The study is a time series analysis using monthly global reported cases of MERS-CoV by the World Health Organisation between January 2015 and January 2018. We decomposed the series into seasonal, irregular and trend components and identified patterns, smoothened series, generated predictions and employed forecasting techniques based on linear regression. We assessed contributions of various risk factors in MERS-CoV cases over time. Successive months of the MERS-CoV cases suggest a significant decreasing trend (P = 0.026 for monthly series and P = 0.047 for Quarterly series). The MERS-CoV cases are forecast to wane by end 2018. Seasonality component of the cases oscillated below or above the baseline (the centred moving average), but no association with the series over time was noted. The results revealed contributions of risk factors such as camel contact, male, old age and being from Saudi Arabia and Middle East regions to the overall reported cases of MERS-CoV. The trend component and several risk factors for global MERS-CoV cases, including camel contact, male, age and geography/region significantly affected the series. Our statistical models appear to suggest significant predictive capacity and the findings may well inform healthcare practitioners and policymakers about the underlying dynamics that produced the globally reported MERS-CoV cases.

Coagulase-negative staphylococci isolated from blood or spinal fluid during a period of 1 year in a department of neurosurgery, were analysed by biotyping, antibiotic resistance pattern and plasmid profiles. Altogether 41 isolates from 19 patients were studied. About 90% of the isolates were Staphylococcus epidermidis. The antibiotic resistance pattern seemed to be closely related to antibiotic usage in the unit. Most common was resistance to penicillin (63%), trimethoprimsulphamethoxazole (49%) and cloxacillin (39%) while resistance to gentamicin was seen in only one strain.

In several cases species and antibiograms were identical in isolates from different patients. Plasmid pattern analysis could then be used for identification of different strains. In one instance, plasmid pattern and restriction enzyme analysis confirmed that two patients probably were infected by the same strain.

Over the last 30 years, HIV/AIDS has emerged as a major global health challenge. This study evaluates the change of HIV/AIDS mortality rates in Asian and North African countries from 1990 to 2010 using the Global Burden of Disease (GBD) study. HIV/AIDS mortality rates were derived from the GBD database from 1990 to 2010, for 52 countries in Asia and North Africa. First, a Latent Growth Model was employed to assess the change in AIDS mortality rate over time in six different regions of Asia, and also the change in AIDS mortality rate over time for males and females in Asia and North Africa. Finally, Latent Growth Mixture Models (LGMMs) were applied to identify distinct groups in which countries within each group have similar trends over time. Our results showed that increase in mortality rate over time for males is about three times greater than for females. The highest and lowest trend of AIDS mortality rates were observed in South-East Asia and high-income Asia-Pacific regions, respectively. The LGMM allocated most countries in the South and South-East region into two classes with the highest trend of AIDS mortality rates. Although the HIV/AIDS mortality rates are decreasing in some countries and clusters, the general trend in the Asian continent is upwards. Therefore, it is necessary to provide programmes to achieve the goal of access to HIV prevention measures, treatment, care, and support for high-risk groups, especially in countries with a higher trend of AIDS mortality rates.

The results of treatment of influenza virus strains with chemical reagents acting on the higher-order structure of protein molecules shows that both the haemagglutinating and enzymic activities are susceptible to these agents but there are considerable differences between the different strains and the neuraminidase activity is more sensitive than the haemagglutinating activity.

The neuraminidase activity of A and A1 strains is destroyed by urea, guanidine, urea+dithiothreitol and mercuric chloride. The haemagglutinin of the PR 8 and SWINE strains is resistant to urea and mercuric chloride but destroyed by guanidine and by urea+dithiothreitol. The haemagglutinin of the DSP strain of virus A and the A1 strains is resistant to urea, guanidine and mercuric chloride but is destroyed by urea+dithiothreitol.

The neuraminidase activity of the A2 strains is more resistant than that of the A and A1 strains. It is resistant to mercuric chloride and partially resistant to urea but is destroyed by guanidine and by urea+dithiothreitol. The A2 haemagglutinin is resistant to urea, urea+dithiothreitol, and mercuric chloride but is destroyed by guanidine.

The LEE virus neuraminidase is resistant to urea and partially resistant to guanidine but is destroyed by urea+dithiothreitol and mercuric chloride. The LEE haemagglutinin is resistant to urea, guanidine and mercuric chloride but is destroyed by urea+dithiothreitol.

It is suggested that the surface projections of the virus particle are protein polymers each made up of three or four monomers which are the components of the V antigen complex. Antigenic activity is a function of the primary or secondary structure of the monomers, haemagglutinin activity is a function of the tertiary structure of the monomers, while neuraminidase activity is a function of the quaternary structure of the polymer.

From studies of the chemical reactions of their haemagglutinins and neuraminidases strains of influenza virus A can be classified into groups. These groups are very similar to but not precisely identical with groupings made by serological methods.

More than 25 years have passed since the last rubella epidemic in the United States. The rubella pandemic of 1964–5 demonstrated clearly the extraordinary teratogenic potential of the rubella virus. In the United States alone, it is estimated that more than 12500000 cases of rubella occurred during the winter and spring of 1964–5. Congenital rubella infection occurred in an estimated 30000 pregnancies, 10000 resulting in fetal death or therapeutic abortion and 20000 resulting in infants born with congenital rubella syndrome (CRS) [1]. In contrast, during 1988, only 225 cases of rubella were reported to the Centers for Disease Control (CDC) in Atlanta, the lowest annual total since rubella became a nationally notifiable disease in 1966 [2]. However, in 1989, this downward trend of reported cases was interrupted, with the number of reported rubella cases in the United States increasing nearly twofold, and in 1990, the total increased another threefold (to more than 1000 cases) [3]. Although the 1990 reports represent the highest total since 1982, the overall incidence of rubella in the United States has still declined by more than 98% since 1969, the year rubella vaccine was licensed (Fig. 1).

Over a period of 9 years in general practice temporary enlargement of the spleen was found in 29 episodes of pharyngitis or tonsillitis, in 2 episodes of acute upper respiratory tract infection other than pharyngitis and in 6 episodes of acute cervical lymphadenitis. In five patients more than one episode of illness associated with splenomegaly was recorded.

In 26 of the 37 episodes a possible aetiology was identified. Evidence only of infection with group A streptococci was found in 14 episodes, adenoviruses or coxsackie B viruses were isolated alone in 4 episodes and in 4 episodes the only finding was the presence in the blood of more than occasional atypical mononuclear cells; in 4 episodes there was evidence of both streptococcal and viral infection. Episodes with evidence of streptococcal infection only tended to be of shorter duration and to be more evenly distributed over the year than were episodes without such evidence. Temporary splenomegaly was noted also in two children with varicella (one of whom also had streptococcal infection) and in an adult with probable rubella.

Early changes in biomarker levels probably occur before bloodstream infection (BSI) is diagnosed. However, this issue has not been fully addressed. We aimed at evaluating the kinetics of C-reactive protein (CRP) and plasma albumin (PA) in the 30 days before community-acquired (CA) BSI diagnosis. From a population-based BSI database we identified 658 patients with at least one measurement of CRP or PA from day −30 (D–30) through day −1 (D–1) before the day of CA-BSI (D0) and a measurement of the same biomarker at D0 or D1. Amongst these, 502 had both CRP and PA measurements which fitted these criteria. CRP and PA concentrations began to change inversely some days before CA-BSI diagnosis, CRP increasing by day −3.1 and PA decreasing by day −1.3. From D–30 to D–4, CRP kinetics (expressed as slopes – rate of concentration change per day) was −1.5 mg/l/day. From D–3 to D1, the CRP slope increased to 36.3 mg/l/day. For albumin, the slope between D–30 to D–2 was 0.1 g/l/day and changed to −1.8 g/l/day between D–1 and D1. We showed that biomarker levels begin to change some days before the CA-BSI diagnosis, CRP 3.1 days and PA 1.3 days before.

Retention in care is a key feature of the cascade of continuum of care, playing an important role in achieving therapeutic success and being crucial for reduction of HIV transmission. The aim of this study was to evaluate the rate of retention in care in a large referral centre in the North of Italy and to identify predictors associated with failed retention. All new HIV-infected subjects were consecutive enrolled from 1 January 2008 to 31 December 2014. Demographics, immune-virological status, hepatitis co-infection and timing of initiation of combined antiretroviral therapy (cART) data were collected at baseline and at the time of last observation. Failed retention in care was defined as lack of laboratory data, clinical visits and drug dispensation for more than 6 months from the last visit. Cox regression analysis was used. Multivariate analysis of variables with P<0.05 in univariate analysis was performed. We enrolled 269 patients (mean age 46.1 years). Males were 197 (73%), Italian 219 (81%) with mean length of disease of 5.1 years. cART was prescribed for 257 patients (95%). The rate of retention in care was 78.4% and the rate of virological suppression was 75%. Predictors of being loss to follow-up were foreign origin (P = 0.048), CD4+ count <200/mmc (P = 0.001) and not being treated for HIV infection (P = 0.0004). Predictors of cART efficacy were shorter duration of HIV infection and baseline HIV-RNA <100 000 copies/ml. These findings underline the necessity to improve retention in care by identifying groups at increased risk of being loss to follow-up. Retention in care of vulnerable population is crucial to reach 90-90-90 UNAIDS endpoint.

During a period of 2 years (2000 and 2001) 996 Shigella flexneri strains from sporadic cases in Israel were sent to the National Shigella Reference Centre (NSRC) by hospital and outpatient clinics. The most common serotypes were 2a, 6 and 1b, accounting for 88·4% of all isolates. They were investigated according to the monthly distribution of the strains, and the age and sex of the patients. The severity of the disease was assessed by a hospital/outpatient distribution (H/Od) of the isolates, based on the location of the sending laboratory. The most affected age groups were 0–11 months and 1–4 years, and the prevalent serotype was 2a, while serotype 6 was dominant in the 5–14 years age group. More cases were registered during the hot season, and there were some serotype-related variations. Overall, 62·1% of the samples were from male patients. Serotype 1b was dominant in the male/female ratio, although it was third in general prevalence. According to the H/Od serotype 2a was more common in hospitalized males and serotype 6 in outpatients, both male and female. These variations, as well as changes in serotype prevalence in the past, underscore the importance of serotype monitoring as part of the public health strategies for reducing the burden of Shigella flexneri infections.

Regular examination of rectal swabs revealed the presence of very low numbers of trimethoprim resistant Escherichia coli in the faeces of 10 batches of calves successively reared in the same shed and none of these strains transferred trimethoprim resistance to E. coli K12. All the calves had received oral doses of 30 mg/kg day of trimethoprim-sulphadiazine for 5 consecutive days. From two subsequent batches of calves reared in the same shed, however, several isolations were made of E. coli with transmissible R factors determining trimethoprim and streptomycin resistance. Shortly before these strains were detected, isolations of E. coli with similar properties had been made from other calves, in a different shed, which had been fed much higher doses of trimethoprim-sulphadiazine. Serological evidence indicated that all the E. coli isolated carrying this R factor belonged to the same strain, which had apparently spread from the second shed to the first. No evidence of ‘in vivo’ transfer of the R factor to other enteric bacteria was obtained.

The action of trypsin and pronase on the haemagglutinins and neuraminidases of eight strains of influenza virus has been examined.

The haemagglutinins of all the strains were highly susceptible to digestion by pronase but there were great variations in resistance to trypsin.

The neuraminidases of the eight strains were of three types. The neuraminidases of the A1 strains and the DSP strain of virus A were highly susceptible to destruction by both enzymes. The neuraminidases of the PR 8 and Swine strains showed partial resistance especially to trypsin, while the A 2 strains and the lee strains of virus B possessed neuraminidases that were completely resistant to both trypsin and pronase.

Proteolytic enzymes released free neuraminidases from the A 2 and lee viruses the morphology of which was different from that of neuraminidases released by detergent treatment.