1. The tuberculin reaction properly applied is a reliable test of the presence of tuberculosis in cattle.

2. A method of segregation is described by which any herd can be rendered tuberculin negative in three to four years without diminution of the herd.

3. Evidence is given that recovery from a tuberculous infection can take place in cattle.

4. Calves can only be infected with tuberculosis after birth, such an infection may, however, take place extremely rapidly within the first few days of life.

5. Artificial feeding of calves with sterilised milk must be supplemented by some vitamine-containing food, otherwise “joint ill,” corresponding to rickets in human beings, will develop at about the third or fourth month. Bull calves are more susceptible to “joint ill” than heifers.

Vedder and Clark (1912), reporting observations on polyneuritis gallinarum based on experiments lasting for several years during which time over 200 fowls were used, make the following statement with regard to the relation between the amount of polished rice eaten and the time of development of neuritis.

A study is described of influenza A anti-neuraminidase antibodies in the sera of young people of three different age groups. Each serum was individually absorbed with viruses containing the N2 neuraminidases of 1957, 1968 and 1972. Rabbit antisera prepared against the viruses were similarly absorbed. Results obtained with the animal sera suggested that these neuraminidases were antigenically distinct, but the human sera had a broader range of anti-neuraminidase activity and gave indication of asymmetric antigenic relationships. Earlier workers who surveyed anti-haemagglutinin antibodies reported that the virus of primary infection absorbed all antibodies, and the virus of secondary infection only those directed against itself. We too found that the virus of secondary infection absorbed only homologous anti-neuraminidase antibody. However, although the primary infecting virus did absorb some secondary antibody, this absorption was incomplete and it lessened with the lengthening of the time interval between the primary and secondary infecting viruses. A similar pattern was seen with anti-haemagglutinin antibodies.

Absorption of anti-neuraminidase antibodies from human sera proved much more difficult than absorption of anti-haemagglutinin antibodies particularly after repeated influenza virus infections. The relative rarity of antigenic shift in the neuraminidase subunit also creates problems in the interpretation of results of serum neuraminidase antibody surveys.

The purpose of this paper was to determine how contact behaviour change influences the indoor transmission of influenza A(H1N1)pdm09 among school children. We incorporated transmission rate matrices constructed from questionnaire responses into an epidemiological model to simulate contact behaviour change during an influenza epidemic. We constructed a dose–response model describing the relationships between contact rate, viral load, and respiratory symptom scores using published experimental human infection data for A(H1N1)pdm09. Findings showed that that mean numbers of contacts were 5·66 ± 6·23 and 1·96 ± 2·76 d−1 in the 13–19 and 40–59 years age groups, respectively. We found that the basic reproduction number (R0) was <1 during weekends in pandemic periods, implying that school closures or class suspensions are probably an effective social distancing policy to control pandemic influenza transmission. We conclude that human contact behaviour change is a potentially influential factor on influenza infection rates. For substantiation of this effect, we recommend a future study with more comprehensive control measures.

This study compares the presence and level of measles haemagglutination inhibiting antibody in the sera of primary school children in selected rural and urban areas of Kaduna State, Nigeria following a vaccination campaign. The results, analysed by Mann-Whitney statistical test at α=0·05, showed significantly higher levels of haemagglutination inhibiting antibody in all the age groups in urban areas when compared with rural areas. The implications of these findings on measles vaccination campaigns are discussed.

We have recently had the opportunity of studying a plague epidemic that broke out on Terceira Island, Azores, in 1908. Terceira Island contains a population of 45,000 souls, the epidemic spread over 27 parishes. About 260 persons were attacked, with a mortality of about 48%.

The antigenic response of guinea-pigs to live poliomyelitis viruses of all three types has been studied and the loss of antigenicity involved in inactivation by formaldehyde and by ultra-violet light have been determined.

We wish to acknowledge the debt we owe to the late Prof. M. van den Ende for his great help and interest in this work, and we are grateful for the assistance received from Dr H. Malherbe and Ruth Harwin in carrying out many of the titrations, and from Dr T. Mead for synthesizing some 1:4-diphenylbutadiene for use as a filter for ultra-violet light.

We also have to thank G. S. Turner, T. Norcott, Doreen Deeks and Margaret Pakes for their technical help.

A clinical trial to determine the effect of oral Humatin therapy on the course of the chronic enteric carrier state in a group of twenty-seven typhoid and paratyphoid B carriers is described. It is concluded that the drug when administered orally in this group of carriers fails in the dosage given to effect a cure of the carrier state.

In order to clarify the failure to isolate Shigella spp. by direct plating, we compared frequencies of Shigella spp. isolation by direct plating and by plating after enrichment in selenite broth. A total 67 strains were isolated in this study. The strains of 38 (56·7%) were isolated only by direct plating, and 25 (37·3%) strains were isolated by both direct plating and after enrichment. Four strains (6·0%) were isolated after enrichment but not by direct plating. Since 6% of isolated Shigella spp. were not isolated by direct plating, we recommend that direct plating and additional isolations from selenite broth should be performed. The significance concerning reduction of concentration of sodium selenite in enrichment broth is discussed.

Antistreptolysin O titres in the sera of children in a rural population of Ceylon were determined, to establish the upper limit of the normal ASO titres in nonrheumatic children, and to compare these ASO titres with results of surveys done in other countries.

Swabs were taken from throats and ulcers of the children examined and cultured specifically for group A haemolytic streptoccoci. Of a total of 257 children, 29·5 % had ASO titres of over 166 Todd units. The greatest number of children showed ASO values between 100 and 166 units. The percentage of children showing values over 166 units increased with age until a maximum of 54 % was reached between 9 and 10 years. Group A haemolytic streptococci were isolated from five throat swabs, but there were no isolations from ulcers. The values obtained from this survey have been compared with those from a few other developing countries.

In a recent number of this Journal1, I have pointed out that the well-known antagonistic action of Ca to Na, was probably at the bottom of the peculiar “defense rupture” action of Ca, as described by Bullock and Cramer2, in relation to infection with the organisms of gas gangrene.

Levels of maternally transferred antibodies against the surface antigen of the A/Texas/1/77 strain of influenza virus showed the expected decline during infancy when measured by complement fixation (CF). However, this decline was not observed when these antibodies were measured by haemagglutination-inhibition (HI). It has been postulated that this discrepancy is due to the acquisition, in the early days of life, of non-specific serum factors which increase the HI activity of sera. The levels of these factors were determined indirectly by calculating HI: CF ratios and it was shown that the factors are rapidly acquired by children between the fifth and twentieth week of life.

1. The view is advanced that the endotoxin of the meningococcus is one of a group of thermostable intracellular bacterial poisons, and that it is not a specific antigenic toxin. 2. The inability of the “endotoxin” to function as an antigen does not lessen its importance as a pathogenic factor in cerebrospinal fever, since the lesions that are associated with the presence of the meningococcus in the tissues are apparently attributable to the pyogenic action of the intracellular poison.

The microporous polyethylene hollow fibre membrane is capable of adsorbing small-sized lipopolysaccharides (LPS) prepared by sonication dispersion, column chromatography on Sephadex G-75 and filtration through a filter membrane with a nominal pore size of 0·025 μg. Small-sized LPS had a one-thousandth of endotoxin activity as compared to intact LPS, when determined by the Synthetic Chromogenic Substrate method of LAL with a specific endotoxin activity of 73·7 ng/μg LPS. Fluorescent microscopy of fluorescein conjugated LPS on a microporous polyethylene hollow fibre showed that fiuorescein-LPS was adsorbed through the entire depth of the membrane texture. Accordingly the adsorption capacity of the filter for small-sized LPS was determined as 1·65 mg LPS/3·68 m2 surface/116 mg fibre/module.

This study used linked national tuberculosis (TB) and HIV surveillance data to investigate recent trends and factors associated with HIV co-infection (TB-HIV) in healthcare workers (HCWs) with TB in England and Wales. Methods applied were the χ2 trend test and logistic regression. Overall 14% (231/1627) of HCWs with TB were co-infected with HIV, increasing from 8% in 1999 to 14% in 2005 (P<0·001). Most (78%) HCWs were non-UK born and 74% of these developed TB ⩾2 years post-entry. Being born in Sub-Saharan Africa was an independent predictor for TB-HIV, especially for female HCWs (odds ratio 66·5, 95% confidence interval 16·3–271·1), who also had a lower median CD4 count than other co-infected women (106/mm3, interquartile range 40–200, P<0·01). Voluntary HIV testing of new HCWs should be encouraged as an opportunity for early diagnosis. Post-entry, a high index of clinical suspicion for TB in those most at risk remains important.

The preparation of a medium that would allow the bacillus of diphtheria to grow and exclude all other organisms would be an ideal medium for those whose work is concerned with that organism, but, as such a medium has not yet been devised, we must be content with the modifications of the ordinary media which we possess. Various varieties of media have been prepared for the purpose of favouring the growth of B. diphtheriae, but very little seems to have been done with regard to selective media.

The SARS-CoV-2 pandemic persists with global repercussions. Initial COVID-19 symptoms encompass pneumonia, fever, myalgia, and fatigue. The human immune system produces IgM and IgG antibodies in response to SARS-CoV-2. Despite previous research, a comprehensive understanding of the interplay between clinical manifestations and humoral immune responses remains elusive. This study aims to scrutinize this association. 134 COVID-19 patients were enrolled, and stratified into mild, moderate, and severe symptom groups. Serum IgM and IgG levels were assessed thrice at one-month intervals using ELISA. The findings reveal significant elevation in serum IgG levels in moderate compared to mild cases (P < 0.001). Additionally, IgG production was significantly heightened in severe cases compared to both mild (P < 0.0001) and moderate (P < 0.05) groups. IgM and IgG levels peaked initially and diminished over time. While anti-SARS-CoV-2 antibodies are expected to confer protection, the direct correlation between IgG levels and symptom severity may arise from delayed immune activation, resulting in an intense antibody response in severe cases. Given evidence linking delayed immune function with a dysregulated innate immune response, comprehensive data collection should encompass not only serum IgG and IgM, but also early measurement of type I interferons at symptom onset. This could provide a more thorough understanding of COVID-19 progression.

1. The chain of evidence incriminating the house fly as a disseminator of typhoid fever is at present fairly complete, but many of the links are weak and not thoroughly strengthened by experimentation.

2. The bulk of experimental work has hitherto been done under highly unnatural and artificial circumstances and the results so obtained cannot be accepted unreservedly as giving a correct view of conditions in nature.

3. The experiments described in the present paper show that flies can ingest typhoid bacilli from natural matter, i.e. human faeces and urine, and carry them for a certain period of time.

4. There is no evidence to show that the typhoid bacilli multiply in the house fly. On the contrary the evidence goes to show that they are not adapted for prolonged life on or in the fly.

5. It thus follows that the house fly is a purely mechanical carrier of the typhoid bacillus and is not a natural “host” in the strict sense of the term.

6. Many bacilli closely resembling B. typhosus in cultural characteristics appear to be natural or, at least, common inhabitants of the intestine of the house fly. These are extremely likely to be mistaken for B. typhosus unless the most stringent tests are employed.

7. As might be expected there is evidence to show that a process of bacterial selection occurs in the fly's intestine. Some bacteria appear to flourish but others are rapidly eliminated. Among the latter must be numbered B. typhosus.

I have to thank my colleagues at the Lister Institute, particularly Dr Ledingham, Dr Henderson Smith and Dr Petrie, for much valuable help and advice during the course of these investigations. To Prof. Bainbridge, Dr Arkwright, Dr Penfold and Dr Macalister my thanks are also due, inasmuch as they helped to smooth over many difficulties both theoretical and practical.