1. The reaction of slowly growing pathogenic bacteria with specific fluorescent antibody provided a means for their rapid identification.

2. Fluorescein isothiocyanate was used to label the globulins of antisera as it had a number of advantages over fluorescein isocyanate.

3. Several other isothiocyanates and a few sulphonyl chlorides tested were inferior to flurescein isothiocyanate as labelling agents. Some of the compounds caused protein precipitation, and others gave a less intense or less distinctive fluorescence than did dluorescein isothiocyanate.

4. The tests were performed by taking impressions of bacterial micro-colonies on glass cover-slips, drying and fixing the preparations, staining them with labelled antiserum, washing in saline and mounting in glycerol saline. The preparations were than examined microscopically under ultra-violet light.

5. Micro-colonies of Br. suis, Past. tularensis and Past. pestis, when treated with homologous labelled antiserum, fluoresced brightly under ultra-violet light and the individual bacteria were sharply defined and stained at the periphery.

6. Micro-colonies of these and other bacteria stained with normal labelled serum, or heterologous labelled antiserum, showed either very dim fluorescence under ultra-violet light, with poor definition of in dividual bacteria, or no fluorescence at all.

7. The technique described permitted specific identification of Br. suis, Past. pestis and Past. tularensis within 20 hr. of inoculation of agar plates with material suspected of containing one of these organisms.

This investigation arose out of a line of work suggested by Dr G. S. Wilson. We should like to thank Dr D. W. Henderson and Major L. H. Kent for providing facilities for the work, Mr E. O. Powell for continual encouragement and supervision of the microscopy, Dr D. W. Henderson, Dr M. C. Lancaster and Dr D. A. L. Davies for supplying antisera, and Mr T. W. Pearce for valuable technical assistance and the photographs.

Ribotype, biotype and resistance phenotype were used to characterize 37 Acinetobacter baumannii–A. calcoaceticus complex isolates responsible for nosocomial infections in Buenos Aires. Nineteen isolates were recovered from endemic infections at 2 hospitals and 18 represent an intensive care unit outbreak that occurred in a third hospital. By ribotyping isolates were classified into five different clones of A. baumannii biotype 2, 3 of A. baumannii biotype 9, and 3 of Acinetobacter genospecies 13. Combination of the three epidemiological markers permitted categorization of 18 outbreak isolates into four probable strains: 2 A. baumannii biotype 2. named type I. and II, and 2 A. baumannii biotype 9. Type I (15 isolates) was the most prevalent strain at one hospital and was responsible for the outbreak. In conclusion, combined analysis of biotypes, resistance phenotypes, and ribotypes was an accurate approach for epidemiologic investigation of A. baumannii. Furthermore, ribotyping discriminated Acinetobacter genospecies 13 isolates which were phenotypically difficult to type.

Human movement contributes to the probability that pathogens will be introduced to new geographic locations. Here we investigate the impact of human movement on the spatial spread of Chikungunya virus (CHIKV) in Southern Thailand during a recent re-emergence. We hypothesised that human movement, population density, the presence of habitat conducive to vectors, rainfall and temperature affect the transmission of CHIKV and the spatiotemporal pattern of cases seen during the emergence. We fit metapopulation transmission models to CHIKV incidence data. The dates at which incidence in each of 151 districts in Southern Thailand exceeded specified thresholds were the target of model fits. We confronted multiple alternative models to determine which factors were most influential in the spatial spread. We considered multiple measures of spatial distance between districts and adjacency networks and also looked for evidence of long-distance translocation (LDT) events. The best fit model included driving-distance between districts, human movement, rubber plantation area and three LDT events. This work has important implications for predicting the spatial spread and targeting resources for control in future CHIKV emergences. Our modelling framework could also be adapted to other disease systems where population mobility may drive the spatial advance of outbreaks.

The waters of one indoor bath and three outdoor baths were examined once an hour during 3 days (bath 1) or 6 days, for available chlorine, redox potential, permanganate number, ammonium, nitrate and total nitrogen, total bacterial count at 22° C., total bacterial count at 37° C. and faecal coliform bacteria. The weather, number of swimmers and the chlorine gas addition were continuously registered, and the pH was checked a few times at each bath. In bath 1, an indoor pool with aluminium sulphate precipitation about once a week and with sand filters back-washed every 2 days, less than 10 bacteria/ml. were found in all samples. In bath 2, an outdoor pool with aluminium sulphate precipitation twice a week and with sand filters back-washed twice a week, also few bacteria were found. In bath 3, an outdoor pool with only filtering through sand filters back-washed about every 14 days, high bacterial counts were found every day except the first, when the filters had been newly back-washed. In bath 4, an outdoor pool with only filtering through sand filters back-washed about once a week, high bacterial counts were found now and then during the first 4 days when the weather was warm, but few bacteria were found the last 2 days when the weather was cold and windy, and there were few swimmers.

Values from different analyses on the same sample showed relatively good correlation between the redox potential and the free available chlorine. In bath 3 both the redox potential and the available chlorine were weakly correlated to the bacterial count, but in bath 4 there was no such correlation. No other factors were well correlated with the bacterial count either.

The bacterial counts at 22° and 37° C. were of the same order. No faecal coliforms were ever found. Use of these bacteria as indicator organism in swimming pools is criticized.

The method of using certain minimum values of the free available chlorine as guarantee for a satisfactory bacteriological quality of the swimming pool water is also questioned. The degree of purity of the water is fundamentally connected with the disinfecting power of the available chlorine.

Use of certain minimum values of the redox potential, according to these investigations, seems to be a method of somewhat greater accuracy. Provided that the methods of precipitation are performed correctly and filters are being back-washed often enough, then an automatically registering redox potential device, perhaps connected to the chlorine gas pump, ought to constitute a good control of the hygienic quality of a swimming-pool water. This must, however, always be completed by bacteriological examinations, preferably made at high bathing load.

On the current conception of the epidemiology of epidemic influenza, as caused by a mechanism of direct spread of the virus from the sick, epidemics must have travelled much more slowly in former times than at present. In contrast, a new hypothesis involving virus latency with seasonal reactivation predicts that in previous centuries influenza epidemics would have spread across the country at much the same speed as in the twentieth century. The study of burial registers in Gloucestershire parishes reported in this paper shows that lethal influenza epidemics at least as early as the sixteenth century can be recognized and dated as at present by the characteristic brief but large excess mortality that they cause. Examples are given showing that the character of the excess mortality caused by lethal influenza has not changed significantly over the centuries, a finding that supports the prediction of the new hypothesis but would not be expected on the current conception of influenzal epidemiology.

In each century, influenzal excess mortalities in Gloucestershire parishes coincided with the date of the relevant influenza epidemic as recorded from widely different parts of Britain, thus further supporting the prediction of the new hypothesis as against current conceptions.

In Brazil, rabies surveillance is based on monitoring domestic and wild animals, although the most prevalent lineage of the rabies virus (RABV) currently diagnosed in Brazil is associated with bats, particularly non-haematophagous bats. Disease control is based on the mass vaccination of dogs and cats. We used data collected by the passive surveillance system of the city of Campinas from 2011 to 2015, to describe the temporal and geographic distributions of the bat specimens and RABV and discuss the current rabies surveillance with the advent of the declaration of canine and feline rabies-free areas in Brazil. We described the species, locations and health statuses of the collected bat specimens. Moreover, all samples were submitted for RABV diagnosis. Then, we performed a time series decomposition for each bat family. Additionally, we determined the spatiotemporal relative risk for RABV infection using the ratio of the kernel-smoothed estimates of spatiotemporal densities of RABV-positive and RABV-negative bats. From the 2537 bat specimens, the most numerous family was Molossidae (72%), followed by Vespertilionidae (14%) and Phyllostomidae (13%). The bat families behaved differently in terms of seasonal and spatial patterns. The distribution of bats varied geographically in the urban environment, with Molossidae and Phyllostomidae being observed downtown and Vespertilionidae being observed in peripheral zones. Concurrently, a significant relative risk of RABV infection was observed downtown for Vespertilionidae and in peripheral zones for Molossidae. No RABV-positive sample clusters were observed. As a result of the official declaration of RABV-free areas in southern Brazil, mass dog and cat vaccinations are expected to halt in the near future. This stoppage would make most dog and cat populations susceptible to other RABV lineages, such as those maintained by non-haematophagous bats. In this scenario, all information available on bats and RABV distribution in urban areas is essential. Currently, few studies have been conducted. Some local health authorities, such as that in Campinas, are spontaneously basing their surveillance efforts on bat rabies, which is the alternative in reality scenario of increased susceptibility to bat-associated RABV that is developing in Brazil.

Japanese encephalitis (JE) is a serious health problem in the southwestern region of Nepal. Serological diagnostic kits for routine diagnostic use in this region have not been available. This study was performed to examine if the particle agglutination (PA) assay for Japanese encephalitis virus (JEV) IgM could be applicable to the samples collected in Nepal and also to evaluate the accuracy of clinical diagnosis of JE. One hundred and ninety-three blood samples were collected from the patients clinically diagnosed with JE or other infectious diseases in the JE-endemic, southwestern region of Nepal, in 2000. The PA assay was performed on these 193 serum samples and the results were compared with those by IgM-capture ELISA. Eighty-six samples were IgM-positive by the PA assay, and 71 of 86 were also positive by IgM-capture ELISA (sensitivity, 99%; specificity, 88%; positive predictive value, 0·82; negative predictive value, 0·99). These results suggest that the PA assay is a simple, reliable and useful diagnostic test to support clinical diagnosis in rural hospitals of Asia including Nepal.

Clinical manifestations of acute bronchiolitis (AB) vary from minimal disease to severe respiratory failure. The response to respiratory viral infections is possibly influenced by genetic polymorphisms linked to the regulation of the inflammatory response. In the present study, we investigated whether interleukin-8 (IL-8) and interleukin-17 (IL-17) genetic variants are associated with the severity of AB. A group of Brazilian infants hospitalized with AB and a control group (infants with no or mild AB, without hospitalization) were genotyped for four IL-8/IL-17 variations. For replication, we studied an Argentinean population sample of infants with mild and severe AB. IL-8 polymorphism (rs 2227543) and IL-17 (rs2275913) variants showed significant associations with the severity of AB. The effect of the IL-8 variation could be replicated in the Argentinean sample. This finding suggests that IL-8 variations may influence the severity of AB in young infants. Further genetic association studies in low- or middle-income populations are necessary with the aim of expanding knowledge in this area.

A human immunodeficiency virus-1 (HIV-1)-positive male undergoing antiretroviral therapy was diagnosed with an axillary lymph node abscess caused by Corynebacterium ulcerans, and an environmental survey revealed that the patient's cat as the source of infection.

The aim of this study was to investigate the prevalent Bibersteinia, Mannheimia and Pasteurella serotypes, risk factors and degree of serotype co-infections in sheep and goats in the Tigray region of Ethiopia. Serum was collected from 384 sheep and goats from the Tanqua-Abergelle district of Tigray region using cross-sectional random sampling. An indirect haemagglutination test was used for serotyping. Risk factors for infections were evaluated by logistic regression. Potential clustering of multiple serotypes within individual animals due to common risk factors was evaluated by redundancy analysis. Eight serotypes were identified: all studied animals were serologically positive for at least one serotype. Overall, 355 (92·45%) of the animals were infected by four or more serotypes. Of the five risk factors studied, peasant association (PA), animal species, age (serotype A1), and bodyweight (serotype T15) were significantly associated with infection, but sex was not significant. Only PA explained a significant proportion of the variation (adjusted R2 = 0·16) in the serological responses. After the effect of PA was accounted for, T3 and T4; A7 and Pasteurella multocida A; and A7 and T10 were positively correlated for co-infection, while T4 and T10 were less likely to be found within the same animal. Diverse serotypes were circulating in the Tigray region and could be a challenge in selecting serotypes for vaccine.

Good antibody responses usually follow infection with Campylobacter jejuni. A comparison of agglutination, complement fixation and immunofluorescence tests was done on 55 sera from 40 sporadic patients with diarrhoeal disease and positive cultures for C. jejuni. Results showed 82 % positive with immunofluorescence, 62 % by complement fixation but only 38 % by agglutination, using two reference strains COP and MEL as antigens. Overall 90 % of the 40 patients were positive by one or more serological tests. Paired sera from 15 patients showed a fourfold or greater rise in only five, confirming previous observations that antibody formation occurs early in the course of infection. Results also suggest that different test systems may be detecting antibodies of different specificities. Results confirm the value of serological tests, but further information on serotypes is required for selection of suitable reference strains.

The importance of carrier animals (those in whom virus persists after recovery from disease or acute infection) and their potential role in the spread of disease remain open questions within foot-and-mouth disease epidemiology. Using simple probabilistic models we attempt to quantify the effect of emergency vaccination – and especially the time of application – on the likely number of such animals, using data from challenge experiments on both cattle and sheep to determine the probability of persistence in diseased and subclinically infected animals. We show that the number of persistently infected animals in a group is predominantly determined by the number of animals initially infected on premises – the high variability of which ultimately limits the accuracy of any predictions of carrier numbers based upon transmission models. Furthermore, results suggest that, within a cattle herd, carrier numbers may be increased if challenge occurs shortly after vaccination. We show that the quality of inspection is the principal factor influencing whether or not carrier herds occur and that, by reducing clinical signs, the application of vaccination in regularly checked stock also results in an increase in undetected persistently infected animals. Where clinical detection would be poor regardless of the use of vaccination (i.e. particularly in sheep), vaccination will result in a reduction in the probability of a group containing undetected carriers: otherwise there is a benefit only if vaccination is applied sufficiently far in advance of any challenge. The implications of the results for serosurveillance are discussed, including the requisite test sensitivity and practices for successful implementation.

From 2000 to 2001, nine strains of Salmonella enterica belonging to the new serotype Keurmassar have been isolated from human and poultry samples at the Senegalese National Salmonella and Shigella Reference Laboratory at the Pasteur Institute, in Dakar. All strains carried virulence factors including Salmonella Pathogenicity Islands (SPI)-1, -2, -3 and -5 encoded genes. Strains did not harbour virulence plasmid. Ribotyping analysis revealed a single clone identical to Salmonella Decatur isolated in Zimbabwe. These data suggest that strains are closely related, and may have been spread clonally. In this new serotype, insertion sequence IS200 is not present.

The membrane-filter assay, GM1-ELISA, and DNA-DNA hybridization assay, were used to detect enterotoxigenic Escherichia coli (ETEC) in samples of water, weaning food, food preparation surface swabs, fingerprints of mothers, and the fingerprints and stools of children under 5 years of age, in 20 households in a Malaysian village. Weaning food and environmental samples were frequently contaminated by faecal coliforms, including ETEC. The membrane-filter assay detected and enumerated faecal coliforms and LT-ETEC in all types of water and weaning food samples. Highest concentrations of faecal coliforms and LT-ETEC were found in weaning food, followed by well-water, stored water and stored drinking water. The GM1-ELISA detected LT-ETEC in weaning food, food preparation surfaces, fingerprints and stool samples. The DNA-DNA hybridization assay detected a larger proportion of STa2-ETEC than the other toxotypes, either singly or in combination. All the assays in combination detected the presence of ETEC in all types of samples on at least one occasion in each household. It was not possible to classify households as consistently more or less contaminated with ETEC. On individual occasions it was possible to show a significant association of the presence of LT-ETEC between the fingerprints of children and their stools, fingerprints of mothers and children, and weaning food and the stools of the child consuming the food.

Wells (1937) discovered that field voles in this country are subject to an epizootic disease due to an acid-fast bacillus. The natural disease in the vole is characterized by the deposition of a cheesy substance in the areolar tissue spaces and the formation in the organs, the lungs particularly, of lesions which have a close resemblance to those of tuberculosis.

Phthisis (pulmonary tuberculosis) is distinguished from nearly all other infectious diseases by its protracted duration and by the prolonged disability which it imposes upon enormous numbers of the total working population. It is further distinguished by the complexity of the influences which are regarded as affecting its spread or capable of controlling its prevalence. It is therefore of the first importance that the relative values of measures for controlling phthisis should be closely studied, and that special attention should be given to those which promise the greatest yield for a given expenditure. In particular it is important to be aware of any which can be set to work without the delay and expense involved in creating a new service. The present paper is intended as a contribution to this study. The facts collected in it and others of a similar kind deserve more extended investigation than it has been possible for me to give them in the intervals of official work. They are put forward here without any illusions as to the inevitable shortcomings of their presentation but with a conviction that from the economic standpoint they are of fundamental importance in the prevention of phthisis.

Estimating the lengths-of-stay (LoS) of hospitalised COVID-19 patients is key for predicting the hospital beds’ demand and planning mitigation strategies, as overwhelming the healthcare systems has critical consequences for disease mortality. However, accurately mapping the time-to-event of hospital outcomes, such as the LoS in the intensive care unit (ICU), requires understanding patient trajectories while adjusting for covariates and observation bias, such as incomplete data. Standard methods, such as the Kaplan-Meier estimator, require prior assumptions that are untenable given current knowledge. Using real-time surveillance data from the first weeks of the COVID-19 epidemic in Galicia (Spain), we aimed to model the time-to-event and event probabilities of patients’ hospitalised, without parametric priors and adjusting for individual covariates. We applied a non-parametric mixture cure model and compared its performance in estimating hospital ward (HW)/ICU LoS to the performances of commonly used methods to estimate survival. We showed that the proposed model outperformed standard approaches, providing more accurate ICU and HW LoS estimates. Finally, we applied our model estimates to simulate COVID-19 hospital demand using a Monte Carlo algorithm. We provided evidence that adjusting for sex, generally overlooked in prediction models, together with age is key for accurately forecasting HW and ICU occupancy, as well as discharge or death outcomes.

As part of the bacteriological quality control programme of the Public Health Laboratory Service, we were asked to investigate the possibility of providing simulated water samples for distribution to the laboratories. For this purpose it was necessary to find some means whereby suspensions of coliform organisms and Escherichia coli could be kept relatively stable in number at room temperature for a period of 7–10 days. This, it was finally found, was best achieved by adding selected strains of the organisms to improved formate lactose glutamate medium (Gray, 1964) without the lactose but with added boric acid to a final concentration of 1·8%.

The procedures adopted in the successful quality control programme are described.

Considerable errors arose when the plate count method was used to determine the number of bacteria on dehydrated vegetables. Bacteria probably occurred on the surface of the vegetables only.

Plate counts tended to be greater when suspensions were prepared at higher temperatures over the range 10–40° C. Counts often increased by 20% and sometimes by 50% in the short period allowed in the standard procedure (25 min.), probably owing to multiplication of bacteria. Changes in the volume of suspensions, caused by rehydration of vegetables, led to small errors for which allowance could be made. Larger variations in count arose from sampling errors through differences in the number of bacteria on individual strips and, to a lesser extent, through imperfect distribution of bacteria in suspensions. The relation of plate counts to the actual number of bacteria on the vegetables was uncertain.

However, the error in counting a single sample (— 65% to + 150%) was appreciably smaller than that in counting successive samples from the same factory (about fivefold) and this in turn was less than the variation between different factories (up to a thousandfold). The plate count could therefore be used with some confidence as a general guide to the state of factory hygiene.

The author is grateful for assistance given by Dr M. Stephenson, F.R.S., of the Biochemical Laboratory, Cambridge, and by Dr M. Ingram, Dr H. G. Wager and others of the Low Temperature Research Station, Cambridge.

Six of 12 men wintering at an isolated Antarctic base sequentially developed symptoms and signs of a common cold after 17 weeks of complete isolation. Examination of specimens taken from the men in relation to the outbreak has not revealed a causative agent.