1. That the epidemic was due to infection of the water supply is borne out by the following points:

(a) The explosive character of the outbreak as shown in Graph II which is characterised by a rapid rise to peak at the end of third week followed by a sharp fall and a gradual tailing off to the end of the epidemic.

(b) The widespread distribution of cases (see Map), no area supplied by water from the city having escaped.

(c) The rapid decline which followed the adoption of appropriate measures to deal with the water supply.

2. 255 persons in the city area (including the 12 military cases) were definitely affected (equivalent to a rate of 3·1 per 1000 of the population). As shown by the rise in the death-rate for the rural area it is apparent that a far greater number of persons were actually attacked.

3. The outbreak had its origin in a defective manhole in the Mental Hospital grounds whereby the sewage overflowed into a rubble drain and infected the water supply. This defect had existed for twenty-five years, and an epidemic in the hospital fifteen years previously established the reservoir from which infection was disseminated through the city.

4. The spread of typhoid was favoured by unsatisfactory arrangements for the filtration of the water supply. This is borne out by the endemic character of the disease prior to the installation of an effective filtration plant.

5. The institution of this plant was followed by an immediate reduction in the incidence of the disease until, as at the present time, water-borne typhoid has been practically eliminated.

6. The value of such a plant combined with chlorination and bacteriological examination has been shown.

Most towns augment their water supply from wells, and in South Africa, where the rivers are said to run underground, Johannesburg is no exception.

Its chief supply is from deep wells in the dolomite some 20 miles to the south-west of the town, but one of the suburbs—Parktown—is not connected to the main supply, but at present draws its water from two wells (the property of the Rand Water Board) which will be subsequently referred to as No. 1 and No. 2, sunk in the shales of the upper Witwatersrand beds. From here the water is pumped to two Water Towers situated at the highest point of the suburb from whence it is distributed by gravitation. For various reasons, the Rand Water Board had decided on replacing the pumping machinery at these wells by electrically driven gear, and advantage was to be taken of the change to properly line and deepen the wells by a steel bore-hole.

1. The problem of assessing nutritional state

This paper emphasizes the need for measurement in diagnosis and recognizes two distinct problems, those of:

(a) Diagnosing specific diseases in the sense of distinct pathological conditions.

(b) Assessing general malconditions where there is no sharp dividing line between the normal and the subnormal.

It suggests a programme of research designed to overcome some of the difficulties inherent in (b) in the case of nutritional assessment.

2. Establishing general health standards

The first requirement is the scientific standardization of the elements making up the concept of health and good physique. This is a complex matter requiring all the help which statistical procedures can give. Moreover, we must check the reliability of the assessors and the indicators which they use before we can place any reliance on results purporting to relate to the population studied.

Provisionally we begin by collecting a battery of indicators of general health; each is then given a graded assessment for each child (and the assessment is repeated to obtain its reliability), and by employing the statistical device of factor analysis we can determine what combination of symptoms will give the highest agreement with the criterion of general health abstracted from these individually imperfect measures. We are actually making explicit the stages which are normally telescoped in the method of ‘general impression’ (which is the method usually adopted in assessing general health, state of nutrition, etc., despite evidence of its unreliability). In this method a number of individual characteristics are fused together without ensuring that different observers will attach equal importance to the signs or even that they will take into account the same ones. The emphasis to be given to each symptom in the final mark is determined statistically by its agreement with the aggregate result. Some indicators may give results so unrelated to the others that they must be eliminated. Other tests, whether physiological, functional or anatomical, may later be added to the battery to reinforce it. A point of practical importance is that some readily assessable symptom or index may be found which gives results in close enough agreement with those of the standard battery to enable it to be used as a substitute, thus shortening the task of diagnosis without appreciably lessening its accuracy.

An alternative criterion could, as we have seen, be the weighted combination of doctors' assessments, for by weighting the results according to each doctor's agreement with his colleagues we were able to increase the agreement between the team result and the hypothetical true mark. However, since the ordinary methods of assessment are unreliable, even the pooled results of the team do not give as good a standard as the standardized battery of tests.

A third standard is sometimes possible in the form of an objective accurately measurable physiological laboratory test or anatomical index. If this is inconvenient to apply generally, any single symptom or pool may be tested by correlation with it to see if the agreement is close enough for practical purposes.

3. Study of more specific nutritional defects

Factor analysis can be used to discover and assess more limited similarities than those covering the whole range of observers or test symptoms. For example, the doctors tended to show group affinities (depending possibly on their different emphasis in diagnosis) in addition to their somewhat low general conformity. Applying similar analytic methods to the study of symptoms, we might isolate specific nutritional deficiencies or it is possible that group factors may be revealed corresponding to the effects of recent or early adverse nutritional conditions respectively.

Whilst the examples of analytic techniques have here been applied to illustrative cases in nutritional and general health assessment, they are equally applicable to other fields of medicine, in particular to endocrinology and to the study of predisposing conditions of disease.

My thanks are due to Prof. Burt and Dr E. H. Wilkins for their suggestions for modifying my original draft. However, this in no way commits them to agreement with the views expressed here.

[Note added in Proof.] Since writing this article I have had an opportunity of correlating and analysing some results of nutritional surveys involving clinical and biochemical signs of malnutrition. The evidence so far obtained indicates a rather weak general factor for clinical signs identifiable with general nutritional state. I hope to be able to give the full results when the material becomes available for publication.

The Virus Reference Laboratory, Colindale, first embarked on laboratory investigations for smallpox early in 1947. From then, in conjunction with the Department of Bacteriology, University of Liverpool, it provided a complete diagnostic service throughout England and Wales until 1962, after which the service became available regionally until eradication was effected. Up to 1970 it had investigated 2696 specimens from suspected cases of smallpox and had recovered 108 strains of variola and 248 of vaccinia virus. These last were from persons suffering the complications of vaccination. Some outbreaks following smallpox importation are discussed but infection among laboratory staff during this period was not demonstrated.

Pregnancies were identified in which maternal IgG antibodies against rubella virus were not detectable by single radial haemolysis. Twenty paired maternal/cord sera were then tested for haemagglutination-inhibiting (HI) activity against rubella virus without kaolin pretreatment of the sera. In the absence of specific antibody, the HI activity observed could thus be ascribed to the effect of non-specific inhibitors. The HI activity in maternal sera was significantly (P < 0·001) higher than that in cord sera. The 20 pairs of sera were similarly tested against a bunyavirus, an alphavirus and a flavivirus, both with and without kaolin pretreatment. The results showed non-specific inhibitors were found to higher titre in maternal sera, with the difference being statistically significant (P < 0·001) for each of the three viruses.

(1) 855 primary cases of typhoid fever in households in Birmingham were investigated.

(2) In 124 or 14·5% of these cases a history of mussel eating within four weeks of the onset of the disease was obtained.

(3) In 17 instances the histories were conclusive of mussel infection.

(4) The curve of mussel-typhoid cases arranged in their weeks of commencement tallies closely with the importation of mussels into Birmingham.

(5) Mussel infection is one of the causes contributing to the autumnal rise of enteric fever.

(6) Some of the sources from which mussels are sent to the Birmingham market are known to be exposed to dangerous sewage contamination.

(7) 65 samples of mussels obtained on entering the Birmingham market from 22 different known sources were analysed bacteriologically.

(8) The results in terms of (a) the total number of organisms, (b) the number of glucose-fermenters, (c) the number of spores of Bacillus enteritidis sporogenes, and (d) the number of Streptococci shew that pollution to a dangerous degree of a large proportion of mussels placed on the market for human consumption exists.

(9) 14 experiments were carried out in relation to mussels subjected to mussels subjected to moist heat at 100°C.

(10) These shew that the ordinary method of cooking to mussels does not remove the risk of typhiod infection and that mussels may be heated in a steam steriliser at 100° C. continuously for as long as four and a half hours without sterilisation.

(11) Legisaltion is necessary to prohibit the gathering of mussels for human consumption from mussel beds exposed to sewage contamination.

Previous studies have suggested that a hospital patient's risk of developing healthcare facility-onset (HCFO) Clostridioides difficile infections (CDIs) increases with the number of concurrent spatially proximate patients with CDI, termed CDI pressure. However, these studies were performed either in a single institution or in a single state with a very coarse measure of concurrence. We conducted a retrospective case-control study involving over 17.5 million inpatient visits across 700 hospitals in eight US states. We built a weighted, directed network connecting overlapping inpatient visits to measure facility-level CDI pressure. We then matched HCFO-CDIs with non-CDI controls on facility, comorbidities and demographics and performed a conditional logistic regression to determine the odds of developing HCFO-CDI given the number of coincident patient visits with CDI. On average, cases' visits coincided with 9.2 CDI cases, which for an individual with an average length of stay corresponded to an estimated 17.7% (95% CI 12.9–22.7%) increase in the odds of acquiring HCFO-CDI compared to an inpatient visit without concurrent CDI cases or fully isolated from both direct and indirect risks from concurrent CDI cases. These results suggest that, either directly or indirectly, hospital patients with CDI lead to CDIs in non-infected patients with temporally overlapping visits.

In these experiments the hook-worm anaemia of dogs does not appear to be exactly analogous to the corresponding disease in man, but differs from it in two essential particulars, namely, that only young animals suffer and that in them its course progresses much more rapidly to a fatal termination.

Older dogs, although not altogether insusceptible, acquire infection only to a moderate extent, which gives rise to a minor degree of anaemia. From this they gradually recover, even in spite of repeated and continued attempts at re-infection.

The anaemia in young dogs was characterised by great loss of weight, emaciation, prostration and intestinal haemorrhage, but in no case was expistaxis observed.

The blood volume of dogs suffering from the minor degree of hookworm anaemia is not materially altered, but if anything is somewhat diminished. The oxygen capacity of the blood per unit of body weight is also, on the average, somewhat decreased.

Infection is generally accompanied by distinct though not profuse haemorrhage, which is most marked in the early stages, but tends to disappear.

Eosinophilia was not a constant sign either of infection or of disease.

Evidence of blood regeneration was furnished by the appearance of large numbers of erythroblasts (normoblasts) which increased with the progress of the disease.

Cats are much less easily infected than dogs, and monkeys are altogether insusceptible. Man, also, were found to be insusceptible to infection with the dog hook-worm.

The Salmonella group contains the organisms which are mainly responsible for outbreaks of food poisoning and the possibility of the production by these strains of bodies which are toxic, or which act as gastro-intestinal irritants, when administered by the oral route, is of practical as well as theoretical interest. This is especially the case if it can be shown that these irritant substances are heat resistant.

1. When fleas bit through films of Tuberculin, Vaccine Lymph, and Staphylococcus Emulsion lying upon the human skin, no inoculation was observed in 188 instances out of 195. In six of the experiments with Tuberculin, inoculation followed, which possibly was not due to the flea-bites. Controls gave positive results.

2. When the same materials were rubbed over recent flea-bites, no inoculations followed. Controls were positive.

3. A very minute dose of Tuberculin, such as might be conveyed by a flea's proboscis, will produce a recognisable reaction in a susceptible person.

4. The bearing of the results on the question of plague transmission is discussed.

Salmonella typhimurium strain 1566 administered to mice by the intraperitoneal route was considerably more lethal than the same dose administered subcutane-ously. This could be measured hi terms of mortality, infectivity and mean survival time of those mice that died.

We analysed the transmission of the human mpox virus in Spain by estimating the effective reproduction number of the disease from official surveillance data. Our computations show that this decreased steadily after an initial burst phase, dropping below 1 on July 12, and thus the outbreak was expected to reduce in the following weeks. Differences in trends were found across geographical regions of the country and across MSM and heterosexual populations.

The risk factors specific to the elderly population for severe coronavirus disease 2019 (COVID-19) caused by the Omicron variant of concern (VOC) are not yet clear. We performed an exploratory analysis using logistic regression to identify risk factors for severe COVID-19 illness among 4,868 older adults with a positive severe acute respiratory coronavirus 2 (SARS-CoV-2) test result who were admitted to a healthcare facility between 1 January 2022 and 16 May 2022. We then conducted one-to-one propensity score (PS) matching for three factors – dementia, admission from a long-term care facility and poor physical activity status – and used Fisher's exact test to compare the proportion of severe COVID-19 cases in the matched data. We also estimated the average treatment effect on treated (ATT) in each PS matching analysis. Of the 4,868 cases analysed, 1,380 were severe. Logistic regression analysis showed that age, male sex, cardiovascular disease, cerebrovascular disease, chronic lung disease, renal failure and/or dialysis, physician-diagnosed obesity, admission from a long-term care facility and poor physical activity status were risk factors for severe disease. Vaccination and dementia were identified as factors associated with non-severe illness. The ATT for dementia, admission from a long-term care facility and poor physical activity status was −0.04 (95% confidence interval −0.07 to −0.01), 0.09 (0.06 to 0.12) and 0.17 (0.14 to 0.19), respectively. Our results suggest that poor physical activity status and living in a long-term care facility have a substantial association with the risk of severe COVID-19 caused by the Omicron VOC, while dementia may be associated with non-severe illness.

Compared with 20, or even 10, years ago our present knowledge of food poisoning outbreaks is extensive and in certain directions fairly complete. In spite of this greatly extended knowledge there are some aspects in regard to which we are yet lacking in fundamental information. This is particularly the case as to the precise sources of infection. It may be accepted as a demonstrated fact that most outbreaks of food poisoning are due to infection of the food eaten with one or other member of the Gaertner group of bacilli. The present paper is only concerned with the outbreaks associated with this group of organisms. A study of the individual outbreaks usually supplies evidence which definitely incriminates a certain article of food, and for most of the recent outbreaks further evidence is forthcoming that this has been infected with one or other member of the Gaertner group of bacilli. Tracing the matter a step further back it is only in a quite small minority of outbreaks that the recorded facts show how the food has become so infected. In a proportion of cases, perhaps more than half for continental recorded outbreaks but in only a small fraction of the British outbreaks, it is true that definite evidence is forthcoming showing that the meat was derived from an animal itself suffering from general or local disease caused by Gaertner group bacilli. Even, however, for these cases our recorded knowledge ceases with this information, and we do not know how these animals became infected or whether they represent isolated cases or are part of widespread epidemics amongst the animals affected.

Middle East respiratory syndrome coronavirus (MERS-CoV) is a zoonotic disease transmitted from dromedary camels to people, which can result in outbreaks with human-to-human transmission. Because it is a subclinical infection in camels, epidemiological measures other than prevalence are challenging to assess. This study estimated the force of infection (FOI) of MERS-CoV in camel populations from age-stratified serological data. A cross-sectional study of MERS-CoV was conducted in Kenya from July 2016 to July 2017. Seroprevalence was stratified into four age groups: <1, 1–2, 2–3 and >3 years old. Age-independent and age-dependent linear and quadratic generalised linear models were used to estimate FOI in pastoral and ranching camel herds. Models were compared based on computed AIC values. Among pastoral herds, the age-dependent quadratic FOI was the best fit model, while the age-independent FOI was the best fit for the ranching herd data. FOI provides an indirect estimate of infection risk, which is especially valuable where direct estimates of incidence and other measures of infection are challenging to obtain. The FOIs estimated in this study provide important insight about MERS-CoV dynamics in the reservoir species, and contribute to our understanding of the zoonotic risks of this important public health threat.