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.

1. None of forty-eight strans of Brucella abortus, ten of Br. melitensis and seven or Br.suis were shown to be lysogenic.

2. It was not possible to ‘adapt’ bacteriophages that were active upon other species of bacteria to lyse brucellas.

3. Thirty samples of faeces, mainly from cows, four sewage samples, twelve specimens of uterine fluid from cows that had aborted, and twenty samples of bulk milk failed to yield bacteriophages active upon brucellas.

Two units, within a mouse-breeding colony, with different breeding systems, have been compared from the point of view of general healthiness of the breeding stock. In one unit the monogamous-pair system, involving post-partum oestrus mating, was employed and in the other the harem system, with isolation of the pregnant females for each litter-down until after the post-partum oestrus. The two units were housed separately and had different staffs. The monogamous-pair unit was accommodated in four small rooms not directly connected; the harem unit in two larger connecting rooms. The methods of cageing, bedding, feeding, watering, care, culling and subsequent procedures were identical for both units and the same system of recording individual detailed information relating to health and breeding was followed for the two units. The size of the two populations studied was 1198 and 1024, respectively, the larger number belonging to the harem unit in which the mice were retained for a significantly longer period. These mice were moved more frequently and handled much more often.

Apart from a small outbreak of Tyzzer's disease (in the harem-bred unit) and sporadic cases in both units spread over the whole period of the survey—some 3–4 years—the general health of the two units was good. There were no cases of salmonella infection, mousepox, pasteurellosis or other serious infections. Throughout the period both units maintained a high standard of productivity and there was no evidence that the mating of the monogamous pairs at the post-partum oestrus led to any weakness or ill health. As would be expected, however, the losses from death and culling were greater among the females in both units.

The health record of the monogamous-pair bred unit was consistently higher than that of the harem-bred unit. There were more cases of Tyzzer's disease in the harem-bred mice and more evidence generally of ill health in this unit. Infertility was three times greater with the harem-bred mice as compared with those in the monogamous-pair unit.

Details of the two systems are discussed and although the records maintained for the two may not be strictly comparable it is concluded that, under the conditions obtaining, the monogamous-pair breeding system yielded a healthier colony of mice than the harem breeding system.

I should like to thank Dr J. S. Patterson and Mr R. Cook for placing many of their records at my disposal, Mr S. Peto and his staff for carrying out much of the tedious compilation of data, and Dr D. W. Henderson, F.R.S., for affording me facilities for this work. To these I am especially grateful for their interest, advice and assistance.

The villages selected for the present series of observations were Dhand and Kasel in the Arnritsar District of the Punjab. They are situated about 10 miles south-west of Amritsar City and within a distance of ¾ mile of each other. They are typical Punjab villages of about 2,000 and 4,000 inhabitants respectively.

In view of the observations made of late years on the action of red light in variola, it was thought that it might be of interest to ascertain, if possible, whether the red, or other rays of daylight, exerted any influence in cases of vaccinia; that is to say, with a disease the specific virus of which differs from that of variola probably only in that its pathogenic capabilities are modified, while vaccinia presents clinically many points of resemblance to variola.

The bed-bug finds an almost ideal environment in a prison, which is centrally heated in winter, and in which it has good harbourage in the wooden cell furniture and an easily available food supply at night. Under such favourable conditions, bugs increase about seventy-fold in a year. It is therefore no mean achievement to obliterate bugs from an infested prison while the prison is still occupied, and is, I think, worth putting on record.

Pre- and post-vaccination serum samples from 278 volunteers, who were given live influenza vaccines, were tested by haemagglutination inhibition (HI) and single radial immunodiffusion tests (SRDT) for antibody to influenza A/Hong Kong/1/68 (H3N2) virus envelope antigens. Those with high antibody titres detected in both tests were less frequently infected, and 85% of the 159 infected showed rises by HI and 70% by SRDT. Similarly, 69 pairs were tested for antibody to Hong Kong (N2) neuraminidase by neuraminidase inhibition test (NI) and by SRD tests. Those with high titres in both tests resisted infection and those who were infected showed a rise in antibody detected both by NI and SRD tests. In general, SRDT was less sensitive than HI and NI in detecting antibody and antibody rises, but in some volunteers it did detect antibody rises which were not detected by conventional tests. Because of its simplicity and speed it appeared to be of use in evaluating such vaccines.

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.

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 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.

1. Recovery of a strain of Brucella abortus Bang from a foetus aborted by a cow in Mauritius is reported.

2. Agglutination tests performed on samples of blood from cows of the Government Dairy indicate that contagious abortion of cattle is present in this country; approximately 24% of the animals from the Government Dairy belonged to the latent or past infection group; 18 % to the active infection group and 15% were presumptive bacilli excreters.

3. As aresult of agglutination tests with the blood serum from man Undulant fever due to Br. abortus is suspected to occur in Mauritius.

(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.

Coronavirus disease-2019 (COVID-19) elicits a range of different responses in patients and can manifest into mild to very severe cases in different individuals, depending on many factors. We aimed to establish a prediction model of severe risk in COVID-19 patients, to help clinicians achieve early prevention, intervention and aid them in choosing effective therapeutic strategy. We selected confirmed COVID-19 patients who were admitted to First Hospital of Changsha city between 29 January and 15 February 2020 and collected their clinical data. Multivariate logical regression was used to identify the factors associated with severe risk. These factors were incorporated into the nomogram to establish the model. The ROC curve, calibration plot and decision curve were used to assess the performance of the model. A total of 228 patients were enrolled and 33 (14.47%) patients developed severe pneumonia. Univariate and multivariate analysis showed that shortness of breath, fatigue, creatine kinase, lymphocytes and h CRP were independent factors for severe risk in COVID-19 patients. Incorporating age, chronic obstructive pulmonary disease (COPD) and these factors, the nomogram achieved good concordance indexes of 0.89 [95% confidence interval (CI) 0.832–0.949] and well-fitted calibration plot curves (Hosmer–Lemeshow test: P = 0.97). The model provided superior net benefit when clinical decision thresholds were between 15% and 85% predicted risk. Using the model, clinicians can intervene early, improve therapeutic effects and reduce the severity of COVID-19, thus ensuring more targeted and efficient use of medical resources.

In September 2002, facsimiles were sent to 360 primary-care physicians alerting them to a local outbreak of Q fever. The physicians subsequently submitted serology samples on significantly more patients than in a previously comparable period in 2001. Facsimile cascade assists effective communication with primary-care physicians in an outbreak investigation.

Under the title of “The inference of local degeneracy from a comparison of the vital tatistics of the people,” the late Dr C. S. Morrison, Medical Superin tendent of the County and City Asylum, Hereford, published a somewhat alarming account of the local conditions (Journal of Mental Science, vol. LIII, 1907, p. 795). After showing that the mean quinquennial rate of admissions to the Asylum had risen from 4·8 per 10,000 inhabitants in 1871–1875 to 7·0 in 1891–1895 and after a slight drop in the succeeding period to 7·2 in 1901–1905. (not including boarded-out patients in the latter case), he proceeds to remark upon the prevalence of thyroid insufficiency.

1. The efficiency of plating of phage 13 on the semi-resistant strain Ps. LIII-3bi decreases as the initial bacterial population on the plate is diminished. Addition of Ps. LII extract to the phage before plating with low bacterial concentrations increases the plating efficiency (exhibition effect).

2. An extract of a strain Ps. LIII-lb which is fully sensitive to phage 13 also causes exhibition of this phage on Ps. LIII-3bi.

3. It is suggested that dissolved phage 13 receptors present in extracts of Ps. LII and Ps. LIII-lb have an affinity not only for the phage but also for suitable bacteria and thus cause exhibition. Inhibition (e.g. of phage 14 by the Ps. LII extract) is due to phage receptors having no tendency to adsorb to bacteria.

4. The phage-exhibiting and inhibiting properties of a freeze-dried extract of Ps. LII active when dissolved in 0.85 % NaCl are lost if the solid is dissolved in water and the solution so obtained further diluted with 0.85 % NaCl. Activity is recovered slowly if NaCl is added to the aqueous solution, instantly if the solution is freeze-dried and the residue dissolved in 0.85 % NaCl.

5. The inhibitory properties of the Ps. LII extract for phage 14 are more sensitive to heat and acidity or alkalinity than the exhibitory properties for phage 13.

6. The absence of cross-precipitin reactions between Ps. LII and Ps. LUI-lb suggests that the phage 13 receptors of the two organisms are non-antigenic or different. I am grateful to Prof. M. van den Ende and my colleagues in this Unit for helpful discussions.

During the experimental comparison of different types of hot-water heating systems in a school at Easter 1934 about a thousand kata readings were taken. These were taken mostly in pairs, one immediately after the other, and a third reading was taken only when the first two differed by more than about 10 per cent.