Cryptosporidiosis is the most common cause of outbreaks of disease linked to mains water supply in the United Kingdom and the second commonest in the United States. Recent evidence has suggested that prior population immunity may have an impact on the epidemiology of waterborne outbreaks and in particular prior immunity may reduce the power of case-control studies for demonstrating association between disease and water consumption behaviour. However, the degree of impact of prior immunity on the power of epidemiological studies is not yet clear. This paper reports the results of some simple mathematical models of outbreaks of waterborne disease in populations with varying levels of immunity due to prior water and non-water exposure. The basic outbreak model was run on a spreadsheet. To determine the impact of prior immunity on case-control studies, further analysis was done using a Monte Carlo method to simulate sampling from cases and controls. It was found that moderate degrees of prior immunity due to water associated disease could markedly reduce the relative risk of water consumption on illness in waterborne outbreaks. In turn this would reduce the power of case-control studies. In addition, this model was used to demonstrate the impact of case misclassification and recall bias on case-control studies. Again it was found that within the model, the results of case-control studies could be significantly affected by both these sources of error. Anyone conducting epidemiological investigations of potentially waterborne outbreaks of disease should be aware of the epidemiological problems. Mistakes from case-control studies will be minimized if the outbreak team pays considerable attention to the descriptive phase of the investigation and if case-control studies are conducted as soon as possible after an outbreak is detected.

This study compared the course of coronavirus disease 2019 (COVID-19) in vaccinated and unvaccinated patients admitted to an intensive care unit (ICU) and evaluated the effect of vaccination with CoronaVac on admission to ICU. Patients admitted to ICU due to COVID-19 between 1 April 2021 and 15 May 2021 were enrolled to the study. Clinical, laboratory, radiological parameters, hospital and ICU mortality were compared between vaccinated patients and eligible but unvaccinated patients. Patients over 65 years old were the target population of the study due to the national vaccination schedule. Data from 90 patients were evaluated. Of these, 36 (40.0%) were vaccinated. All patients had the CoronaVac vaccine. Lactate dehydrogenase and ferritin levels were higher in an unvaccinated group than vaccinated group (P = 0.021 and 0.008, respectively). SpO2 from the first arterial blood gas at ICU was 83.71 ± 19.50% in vaccinated, 92.36 ± 6.59% in unvaccinated patients (P = 0.003). Length of ICU and hospital stay were not different (P = 0.204, 0.092, respectively). ICU and hospital mortality were similar between groups (P = 0.11 and 0.70, respectively). CoronaVac vaccine had no effect on survival from COVID-19. CoronaVac's protective effect, especially on new genetic variants, should be investigated further.

A survey into the prevalence of salmonella organisms in sewage in the Borders Region of South-east Scotland is described. A total of 317 isolates representing 34 different serotypes were made, of which only 5 serotypes appeared in animals, supporting the view that the spreading of sewage sludge on to pastureland presents little risk to livestock provided the recommended guidelines are followed. Nevertheless, Salmonella typhimurium phage type 12, identified in sewage, was also recovered from animals in incidents on 11 farms, including 4 which had received sludge from this source. A further 48 isolates (13 serotypes) were obtained from the parallel monitoring of abattoir effluents, indicating that the background level of salmonella infection in the animal population appears to be low in comparison to that in humans.

Antibacterial sera against C. diphtherias gravis (serological type I), intermedius and mitis were prepared in horses. The details of the immunization and the preparation of the sera are described. The sera contained a minimal amount of antitoxin.

The anti-gravis serum in the dose used, when it was given to guinea-pigs 1 hr.before the subcutaneous injection of ten lethal doses of the homologous organism, saved the life of 75 % of the animals. Those which died lived longer than the controls, and C. diphtheriae was recovered less often from the local lesion and the liver than at the same sites in the controls; it was not recovered from the heartblood of the animals which received the experimental serum, whereas cultures from the heart-blood were positive in about 40 % of the controls.

In these experiments the degree of invasiveness of the strain, as judged by the frequency of its recovery in cultures from the heart-blood and the liver of the control animals, corresponded with earner observations (Robinson & Marshall,1934), which showed that in routine virulence tests carried out by the subcutaneous inoculation of guinea-pigs C. diphtheriae could often be cultivated from the local lesion, the liver, the pleural fluid and the heart-blood, and that gravis and intermedius strains were more invasive than mitis strains. This was one of the main facts which suggested that an antibacterial factor might prove to be a useful adjunct in the treatment of diphtheria.

The anti-gravis serum, when given as a supplement to the routine doses of antitoxin to patients with severe diphtheria, had a definitely beneficial influence on the local lesion. Moreover, the serum improved for a time the general condition of some of the patients, including those who died later. The death rate of the group to which anti-gravis serum was administered was similar to that of the control group but, on the other hand, the patients who received the serum lived, on the average, longer than the control patients notwithstanding that treatment of the former group was begun later in the disease. The clinical evidence in favour of the anti-gravis serum cannot be assessed quantitatively, but, since it is based on critical observations, it should not be disregarded.

Consideration of the results as a whole leads us to conclude that the anti-gravis serum used in the tests contained a specific antibody which, within limits, had a beneficial action. We suggest, therefore, that the role of the antibacterial factor in the pathogenesis and control of diphtheria merits investigation.

Between August 1964 and November 1965 Salmonella senftenberg was isolated from poultry, sheep and cattle on eight farms in England and Scotland. From an analysis of the case records its presence would appear to be incidental; but it may contribute to poultry mortality by acting in conjunction with other intercurrent infections or following stressful events such as severe debeaking or cold brooder conditions.

I should like to thank the officers of the veterinary field investigation and research services who made available their records and notes for this work, and who visited the farms and hatcheries, but especially Mr R. Duff, Veterinary Laboratory, Lasswade, for his reports on the turkey poults from farm A; also Dr Betty Hobbs and Mr B. Hanson for their valuable criticisms.

Chemotherapy and/or radiotherapy used as conditioning regimens before autologous or allogeneic haematopoietic cell transplantations (HCTs) cause neutropenia, which is the main reason for bloodstream infections. Autologous HCTs are considered to be superior to allogeneic HCTs in terms of infection outcome. A previous analysis suggested that patients with allogeneic HCTs are exposed to a reduced infection hazard and that an unfavourable infection outcome of allogeneic HCTs may be mediated through prolonged neutropenia. Therefore, we investigated whether allogeneic HCTs initially lead to fewer infections. We evaluated data from a prospective non-randomized multi-centre cohort study, with a total of 1616 patients. Of these, 703 patients received autologous and 913 patients received allogeneic HCTs from January 2000 to June 2004. The retrospective analysis used simultaneous confidence bands for the cumulative infection probability in the presence of competing risks. Patients with allogeneic HCTs experienced fewer infections during the early phase of neutropenia. As patients with autologous HCTs are not necessarily subject to antibiotic prophylaxis, a future study should investigate this policy. A limitation of the analysis is that it did not find the effect of crossing cumulative infection probabilities to be significant.

This paper draws on the mortality records of the French, US and UK Royal navies to reconstruct the spatiotemporal evolution of the 1918–1919 influenza pandemic in global Allied naval forces. For a total of 7658 deaths attributed to respiratory diseases (French and US navies) and all diseases (UK Royal Navy) at 514 locations worldwide, techniques of spatial point pattern analysis were used to generate weekly maps of global mortality intensity in 1918. The map sequence for the main period of pandemic mortality, mid-August to mid-November 1918, revealed a near-simultaneous development of mutiple foci of high disease intensity in three distant locations (Europe, North America, West Africa). Given the relatively slow speed of naval ships in convoy at this time (<12 knots), our findings suggest that the pandemic influenza virus was circulating on three continents at the observed onset of the main mortality wave.

Intravenous provocation (IVP) tests demonstrated that hydroxypropylmethylcellulose (MC) was able to elicit anaphylactic signs in cattle vaccinated with foot-and-mouth disease (FMD) vaccine produced at one centre but not with similar vaccine produced at another. The former vaccine also provoked serum reagins which were demonstrated by passive cutaneous anaphylaxis (PCA) tests in goats.

Reaginic sera which reacted specifically with MC were used in PCA tests to screen samples taken serially from the vaccine production lines. The reactions observed suggested that a substance with MC or similar specificity was present in the antifoaming agent routinely added to vaccines.

As there appears to be a considerable amount of uncertainty (as evidenced by recent writings on this subject) regarding the biological relationships and the etiological significance of the so-called “atypical B. dysenteriae,” this short communication is intended as a brief résumé of conclusions arrived at in the course of an extended investigation of dysentery bacilli in Egypt during 1916 and 1917. It is to be noted that the results recorded here were obtained from the examination of cases of dysentery observed in the earliest stages and frequently followed into convalescence. Such experience has shown that conclusions derived solely from an investigation of the later stages of the disease, e.g. convalescents examined after arrival from over-seas in the United Kingdom, throw little light on the problem of the bacterial etiology of the disease as a whole. In a paper by Thomson and Mackie (1917) on the clinical and laboratory study of dysentery in Egypt a number of atypical dysentery strains were described, but at the time this communication was submitted for publication my observations were not sufficiently complete to make any general statements regarding organisms of this type and no attempt was made to classify them.

RK 13 and primary PMK and VMK cell cultures were compared for the isolation of RV by means of the simultaneous inoculation of original specimens and early passage material. RK 13 was found to be the most sensitive and reliable and provided a result for both isolation and neutralization in the shortest time. As the interpretation of CPE and the propagation of these cultures is sometimes difficult, the simultaneous use of a second system in which RV is easy to identify, e.g. VMK or PMK cell cultures, is recommended. Both PMK cell cultures and LLC-RK1 were suitable for isolating RV from clinical specimens. Preliminary studies with LLC-RK 1 indicate that it may provide an even more sensitive alternative to RK 13, but further studies employing clinical material require to be carried out before firm conclusions can be reached.

A cylinder filled with medium is described, with which prints are made of floors or other surfaces. After a print has been made a slice is cut off the medium, put in a Petri dish and incubated. With one filled cylinder about twenty prints can be made. The method can be used for quantitative bacteriological testing of floors, and the effect of treatment with disinfectants can also be checked in a simple way. Preference was given to disinfection with Halamid.

One hundred and nine strains of Haemophilus influenzae type b were subtyped by sodium dodecyl sulphate polyacrylamide gel electrophoresis of whole-cell polypeptides. Twenty-one strains from England, 44 from Scotland, 8 from Sweden, 6 from the Netherlands and 30 from the USA were examined. Some of these strains had been subtyped by outer membrane protein analysis; most of the strains had been isolated from cases of invasive disease.

Comparison of polypeptide profiles using the Dice coefficient of similarity showed that the majority of European strains were closely related and formed a single large group. Four smaller groups were identified; three of these included American and European strains, indicating a world-wide distribution of subtypes. However, the common European and American subtypes fell into different groups, indicating the existence of marked geographical variations in subtype frequency.

A molecular epidemiological study was carried out on 60 Salmonella dublin isolates identified at the Southern Italy Enterobacteriaceae Center between 1971 and 1985. These included 23 isolates from children with diarrhoea in Palermo obtained during 1984.

All isolates from the outbreak of gastroenteritis in children were resistant to chloramphenicol and streptomycin and harboured two plasmids of 50 MDa and 3 MDa molecular weight, whereas the majority of the isolates identified before 1984 were susceptible to these antibiotics and carried only a 50 MDa molecular weight plasmid. Four S. dublin strains successively identified from cattle (Palermo, Foggia, Portici) and from a child (Palermo) were shown to possess similar antibiotic resistance patterns and plasmid profiles to S. dublin isolates from the outbreak of gastroenteritis in children.

The 50 MDa plasmid was shown to be associated with virulence in mice, while it was not possible to assign any genetic function to the 3 MDa plasmid.

Understanding patterns of influenza spread and persistence is crucial for pandemic preparedness. The H1N1pdm09 virus caused the first influenza pandemic of the 21st century which resulted in at least 18500 deaths. Based on laboratory-confirmed primary-care case reports we investigated the role of weather conditions and socio-demographic variables in its initial spread and subsequent presence in France. Our findings suggest that low relative humidity and high population density were determinants in shaping the early spread of the virus at the national level. Those conditions also favoured the persistence of viral presence throughout the first 33 weeks of the pandemic. Additionally this persistence was significantly favoured by low insolation. These results confirm the increasingly recognized role of humidity in influenza dynamics and underlie the concomitant effect of insolation. Therefore climatic factors should be taken into account when designing influenza control and prevention measures.

Four red cell antigen-antibody systems in the rabbit are described.

Three of these systems, Z, Y and W, appear to be inherited as an allelomorphic series. The fourth is inherited independently.

Some of the serological properties which allow these sera to be recognized are described and attention is drawn to a property of rabbit red cells, manifested by a variation in their susceptibility to agglutination by homologous antisera, which can complicate the separation of a mixture of antibodies in one serum.

Urinary tract infection (UTI) is common in children aged <5 years with diarrhoea, but little is known about risk factors, aetiology and outcome of such children. We aimed to evaluate these knowledge gaps of UTI in children aged <5 years with diarrhoea. We enrolled all children aged <5 years with diarrhoea admitted to Dhaka Hospital of the International Centre for Diarrhoeal Disease Research, Bangladesh, between May 2011 and April 2013, who had history of fever (⩾38 °C) and obtained a urine sample for culture. Diarrhoea with UTI (confirmed by culture) constituted cases (n = 26) and those without UTI constituted controls (n = 78). Threefold controls were randomly selected. The case-fatality rate was comparable in cases and controls (4% vs. 1%, P = 0·439). Escherichia coli (69%) and Klebsiella (15%) were the most commonly isolated pathogens. Persistent diarrhoea, pneumonia and prior antibiotics use were identified as risk factors for UTI in logistic regression analysis (P < 0·05 for all). Thus, children with diarrhoea presenting with persistent diarrhoea, pneumonia, and prior antibiotic use should be investigated for UTI for their prompt management that may reduce morbidity.

Little is known about HIV drug resistance (HIVDR) in newly diagnosed HIV-infected adults in eastern China where the HIV epidemic is spreading predominantly through sexual contact. During 2008–2011, newly HIV-diagnosed adults in Taizhou prefecture, Zhejiang province in eastern China were examined for HIVDR by amplifying and sequencing the HIV-1 pol gene. Of 447 genotyped participants, 53·7% were infected with CRF01_AE, 20·1% with CRF07_BC, 12·5% with subtype B, and 11·6% with CRF08_BC. Most of the participants had one or more minor genetic mutations in the pol gene that are associated with HIVDR. Twelve (2·7%) participants met the standard guidelines of having low to high HIVDR, suggesting that the prevalence of HIVDR in newly HIV-diagnosed adults was low in the study area and current antiretroviral therapy (ART) regimens are likely to remain effective. However, given high frequency of minor HIVDR in HIV patients and the scaling up of ART programmes in China, larger HIVDR surveillance programmes are needed.

An outbreak of food poisoning caused by Salmonella typhi-murium, phage-type 12, in which 122 persons were infected, is described.

Isolation of the same organism from the drains of two large abattoirs, from pig faeces at one abattoir, and from the floor drains of fifteen out of fifty-four butchers' shops and bakehouses examined, together with records showing that this organism had been recently isolated from pigs and cattle in the neighbourhood, suggested that meat was the vehicle of infection.

We are indebted to Dr E. S. Anderson and the staff of the Central Enteric Reference Laboratory and Bureau, Colindale, for phage-typing the cultures of S. typhi-murium.

We should like to thank Prof. Scott Thomson for his encouragement and advice in the preparation of this paper and Mr J. Morgan and Mr B. M. Jones of the Public Health Laboratory, Cardiff, for their technical assistance.

1. The circumstances attending an outbreak of haemolytic streptococcal infection in a training centre, followed by acute rheumatism, are described.

2. The incidence of streptococcal infections in trained men and apprentices was 64 and 474 per 1000 respectively.

3. Of streptococcal infections 78·0% occurred in members of two younger classes of apprentices.

4. The eight cases of acute rheumatism were all in apprentices, seven cases being in the same two classes. All but one case had had tonsillitis or scarlatina during the epidemic.

5. The smallest percentage of post-epidemic Dick-positive reactors was found in the youngest class which had suffered most in the outbreak.

Typhoid fever is an illness caused by Salmonella enterica serotype Typhi. In developing regions, it affects an estimated 20 million people annually, causing 200 000 deaths. Although uncommon, cases occur in the USA each year, predominantly due to international travel. During February 2015, the Oklahoma State Department of Health (OSDH) detected an outbreak of typhoid fever among residents of northwestern Oklahoma. OSDH conducted case-patient interviews to identify the source and symptomatic contacts. Whole genome sequencing (WGS) was performed to characterise the genetic relatedness of isolates among the four outbreak-associated pulsed-field gel electrophoresis (PFGE) patterns. We identified 38 cases, 25 confirmed and 13 probable, in two states. WGS revealed a 0–10 single-nucleotide polymorphism variation between isolates. Although we were unable to determine the source, almost all case-patients were members of the Marshallese community that attended a common event in Oklahoma, or were contacts to a confirmed case. This is the largest outbreak of typhoid fever in the USA since 1989, and first to apply WGS to complement interpretation of PFGE results during a typhoid fever outbreak investigation. This investigation illustrates the potential risk of outbreaks among communities comprised of international populations from regions where typhoid fever remains endemic.