We attempted to predict epidemics of influenza B, focusing on B/Victoria/2/87-like (V) and B/Yamagata/16/88-like (Y) lineages, in Yamagata, Japan. We collected 9624 nasopharyngeal swabs for virus isolation from patients with respiratory infections between 1996 and 2003 and 237 sera for seroepidemiological analysis by haemagglutination–inhibition test in 2001. We isolated 424 V-lineage and 246 Y-lineage viruses during the study period. Three herald viruses in the 2000–2001 season enabled us to predict a V-lineage epidemic in the following season. However, another V-lineage epidemic occurred in the 2002–2003 season, although we caught four herald Y-lineage viruses, whose antigenic drift was suggested by seroepidemiological study, at the end of the previous season. Since the epidemiology of the two influenza B lineages remains unclear, a careful watch should be kept on these lineages in order to provide effective public-health strategies against future epidemics.

We analysed a strain collection representative of the overall Neisseria meningitidis population circulating in an open community (46000 inhabitants, Spain) during an endemic period (30 isolates from patients and 191 from throat cultures of healthy individuals) by both phenotypic and molecular techniques. Almost all patient isolates were assigned to three hyper-virulent lineages (ET-5 complex, ET-37 complex and cluster A4) by both multilocus enzyme electrophoresis (MEE) and pulsed-field gel electrophoresis (PFGE). In contrast, MEE and PFGE assigned 20% and 15% respectively of carrier isolates to the hyper-virulent clones (4% for both methods together). There was also a higher correlation between PFGE and phenotypes associated with virulent clones. These notable differences between the two molecular methods were further observed in more than half the carrier isolates, suggesting that the associations between these strains were distorted by recombination events. However, almost one-third of total endemic strains from symptom-free carriers and almost all patient strains belonged to clones defined by MEE and PFGE, with no known epidemiological connection. These data indicate low transmission and a weak clonal structure for N. meningitidis.

The occupational risk of acquiring minor respiratory infections for paediatric student nurses was estimated by performing serological examinations with influenza A, B, C, parainfluenza, mumps, respiratory syncytial virus, adenovirus and Mycoplasma pneumoniae at 6-month intervals over a period of 4 years in paediatric student nurses at two schools of nursing and students at one school of medical technology, litre increases against all tested agents occurred 1·86 times more often in the student nurses than in the medical technology students, the most frequent agents in both groups being influenza A and B. No difference in the relative distribution of the agents could be verified in the two occupational groups. Data on the protective value of pre-infectious antibody levels for influenza A, B, and coronavirus OC43 and on the importance of the spread of single agents among classmates are presented.

Non-typhoidal Salmonella is an important burden, particularly in developing countries of the African region. We report for the first time in Angola, a sub-Saharan African country with commercial/travel relationships with Europe, an unexpectedly high occurrence of Salmonella (n = 12/63, 19%) from a high diversity of sources, particularly farm and wild animals. The detection of diverse serotypes (n = 12), involving putative new S. enterica subsp. salamae serotypes, is also of note, reinforcing the need for a comprehensive surveillance in Angola critical to identify animal/food/environmental sources of salmonellosis with impact on animal health, local people, tourists and exported products.

Two published methods for the maximum likelihood estimation of a common relative potency from a series of parallel-line assays are shown to be equivalent.

1. In order to obtain evidence as to what extent the urban excess in cancer mortality is real, an analysis has been made, in respect of both location of tumour and geographical region, of the cancer mortality statistics for Scotland, 1931–7 inclusive.

2. Of the various locations, the greatest urban excess is shown by cancer of the respiratory tract; this is considered to be largely, though probably not entirely, due to better diagnosis and more accurate certification of deaths in the cities. Next come the buccal cavity and uterus; in both these locations certification is likely to be relatively accurate, so that a real excess would seem here to be present. The other accessible locations, the skin and the female breast, do not show significant urban excesses, but the numbers are small, and the existence of a real urban excess is not excluded. The results are in general agreement with those of the English experience 1911–20.

3. Further analysis of the data presented by Russell for Scotland, 1923–8, reveals an excess in the industrial counties of deaths for cancer of the buccal cavity, and perhaps a smaller one for cancer of the female breast. These data are, therefore, not inconsistent with our findings.

4. As compared with the period 1921–30, the figures for 1931–7 demonstrate, for ages 25–65, a marked improvement in cancer of the buccal cavity and uterus. A recorded fall in cancer of the digestive organs may, in part, be due to more accurate certification in respect of the primary location. The failure of mortality from breast cancer to fall may be due to the same cause. The large increase in lung cancer is almost certainly due, in part, to better diagnosis. For all sites together, the cancer mortality between ages 25 and 65 remained constant for men, and fell by 8% in the case of women. The standardized rate for all ages and both sexes combined increased by 1·3%, a rise which is 2·2 times its standard error.

5. The urban excess cannot be entirely explained as due to incomplete certification in the rural areas. The implied effect of social and industrial environment in stimulating tumour growth is in harmony with the known facts regarding occupational and social cancer, and emphasizes the importance which the control of adverse environmental factors may have in the reduction of cancer incidence.

We evaluated the occurrence of hepatitis C virus (HCV) infection in 97 former soccer players who played in Recife, Brazil in the 1960s and 1970s, and analysed the risk factors for infection, such as history of transfusions, surgery, tattoos, piercings, and the use of illicit drugs or injectable vitamin complexes. Immunochromatographic testing was performed to detect anti-HCV antibodies. All former soccer players were men (mean age 59·2 years), of whom 62 (64%) and 35 (36%) were classified as amateurs and professionals, respectively. Seven (7·2%) tested positive for anti-HCV antibodies; three (4·8%) were amateurs, and four (11·4%) were professionals. In univariate analysis, transfusion, surgery, and use of injectable vitamin complexes were associated with HCV infection, while in multivariate analysis, only the use of injectable vitamin complexes was related (P=0·0005). We observed a high frequency of HCV infection in former soccer players, especially in professionals who used injectable vitamin complexes.

Trimethoprim, a 2,4-diaminopyrimidine derivative which inhibits the growth of some bacteria by interfering with folic acid synthesis, inhibited the growth of several strains of the trachoma agent. Inhibition was most clearly demonstrated by measuring prolongation of mean death time of groups of chick embryos inoculated with a single lethal dose of agent. Over a certain range, prolongation was proportional to the logarithm of concentration of inhibitor; higher concentrations were toxic for the embryo. On a weight basis, trimethoprim was not as active as sulphafurazole. Inoculation in conjunction with sulphafurazole resulted in slight potentiation of activity. A related pyrimidine derivative, the antimalarial drug pyrimethamine, also significantly inhibited the growth of one strain of trachoma.

In cell culture, trimethoprim decreased the number of inclusions formed by a suspension of the trachoma agent and induced morphological changes in the inclusions similar to those caused by sulphafurazole.

Inhibition of the growth of the trachoma agent in the chick embryo was reversed by leucovorin calcium. It is concluded that, as with bacteria, the drug acts by blocking the folio acid cycle and that the trachoma agent most probably contains a dihydrofolate reductase.

Values for the ascorbic acid content of a number of foods sold in diverse markets were determined by titration against 2: 6 dichlorophenolindophenol in acid solution. The results showed that the least expensive material was not necessarily the poorest source of vitamin C and might be more valuable than expensive foods. Samples of cabbage from the cheap market contained 329% as much vitamin C as samples from expensive sources. These results on comparison with figures recorded for fresh garden produce showed that market foods have lost some of their vitamin C content on exposure for sale, but still contain satisfactory amounts of ascorbic acid when purchased.

Results from different samples of fruits and vegetables showed wide variation. No data relating to storage before purchase were available, so limiting figures were used for each food. Mean values were calculated for purposes of comparative tabulation.

The effect of household storage after purchase was noted for foods from inexpensive and fashionable markets. The values obtained showed that the loss of ascorbic acid in foods stored in the home after a period of exposure for sale, though marked, was not as serious as has previously been indicated.

An irregular fall in the ascorbic acid content of some of the material examined was noted and investigated. Wide variations in the amount of ascorbic acid present in different parts of individual fruits and vegetables were observed. In view of experimental results it is recommended that foods be purchased and prepared for consumption immediately before use.

Canned foods from diverse markets were examined to determine their ascorbic acid content, and it was shown that the vitamin is distributed throughout solid and liquid. Although a percentage of vitamin is destroyed on heating, those fruits and vegetables initially high in ascorbic acid retained sufficient vitamin to afford a better, and frequently cheaper, source of vitamin than unheated samples with a low ascorbic acid content. Considerable quantities of vitamin C are lost when the liquid from canned vegetables is discarded. When the syrup from cans is used as well as the fruit the vitamin available to the consumer is frequently greater than the amount yielded by the same weight of raw fruit from market sources.

Raw and canned plant tissues from cheap and expensive sources were compared for their antiscorbutic value in the human diet, and for the cost of the daily requirement at ruling market prices. It was found that a day's ration of ascorbic acid could be purchased at a cost as low as a farthing to as high as a pound.

In this paper a short account is given of the application of photo-electric methods to bacteriology. Although such methods are now well established, and have been used in colorimetry and nephelometry for some years, they have not received the attention they deserve. The apparatus required, apart from the cell, will be found in any well-equipped laboratory; and their simplicity, as well as the elimination of personal errors, should assure the use of such methods in all experiments involving the measurement of colour intensity or turbidity of fluids.

The virulence of strains of the three types of poliovirus have been examined by the subcutaneous injection of monkeys. The strains used were the Sabin attenuated Types 1, 2 and 3, Cox attenuated Types 1, 2 and 3, the Brunenders Type 1 partially attenuated strain, MEF-1, Type 2 and Saukett, Type 3.

The results obtained indicated that the subcutaneous route of injection offers a promising method for comparing and characterizing strains of poliovirus.

1. A weekly examination for haemolytic streptococci was made of the dust of two hospital wards; observations lasted in each ward for about six months. The wards chosen were a combined ear, nose and throat and eye ward used for adult patients, and a children's ward.

2. It was found that on an average for the whole period the dust of the former ward contained 300,000 haemolytic streptococci per gram and the dust of the latter 250,000 per gram.

3. Representative colonies of haemolytic streptococci grown from each sample of dust were examined serologically to determine their group. About 33% of those isolated from the E.N.T. Eye ward were group A and about 80% of those from the children's ward.

4. In order to determine the relationship of the streptococci in the dust to streptococcal infection among patients and staff, throat swabs and swabs from septic lesions were regularly examined.

5. In the children's ward 27·8% of 270 patients were found to be infected with haemolytic streptococci either on admission or at some time during their stay in hospital. The incidence of infection acquired in hospital was more than 12·2%. About two-thirds of these infections were latent.

6. Group A streptococci isolated from the dust and swabs were identified serologically according to type. It was noted that the occurrence of a particular type in the dust often resulted from the presence of one or more infected persons in the ward.

7. It was, however, frequently noted that a particular type made its first appearance in the dust when it could not be cultured from any of the swabs. It is possible that these strains were introduced to the ward by visitors, such as patients' relatives and friends or patients from other wards coming for septic dressings.

8. No conclusive example of a hospital cross-infection conveyed by dust was noted.

I wish to thank Dr T. J. Hennelly and Dr D. G. Morgan, Medical Superintendents of the two hospitals, for giving me the facilities to carry out the investigation; also Dr S. T. Crowther and Dr Duncan Davies, and the sisters and nursing staff for their assistance and co-operation. I am especially indebted to Dr V. D. Allison for his helpful advice and criticism.

Experiments were performed which show that virulent strains of Salmonella paratyphi A contain an additional antigen which has all the properties of a Vi antigen.

The anti-Vi immune serum combined in suitable proportions with an anti-0 immune serum exerted maximal bactericidal effect on virulent strains.

Of thirty-six babies delivered at home 72% acquired Staph. aureus in their noses and throats within their first fortnight of life. The carrier rate among the twenty-eight who were subsequently followed was 65% during the first fortnight period. Only 18% acquired penicillin-resistant strains, in contrast to the previously observed hospital-born group, 97% of whom acquired strains resistant to penicillin. Phage typing demonstrated that the home-born babies who acquired Staph. aureus during their first fortnight carried the same strains throughout the 15–25 week observation period. As in the hospital-born babies, many of them tended to lose the strains from the nose while retaining them in the throat. Strains having phage patterns of Groups I and II were most common among the home-delivered babies, whereas among the hospital-born babies Groups I, III, or untypable strains were most frequent. There was no evidence that the penicillin sensitive strains acquired from the home are carried for shorter periods than the penicillin-resistant strains of the hospital. Babies failing to acquire Staph. aureus within the first fortnight tended either to acquire it in the throat alone, or to remain non-carriers. It is suggested that babies who do not become carriers within the first two months of life are unlikely to do so later.

I owe thanks to many people: to the late Prof. Sir Alexander Fleming for generously extending the laboratory facilities of The Wright-Fleming Institute; to Prof. Robert Cruickshank for patient guidance and invaluable suggestions; to Dr R. E. O. Williams for providing materials and laboratory space for the phage typing, and to Dr Joan E. Rippon for instruction in the phage typing technique; to Dr Agnes H. W. Smythe for the co-operation of the Marylebone and Lisson Grove Child Welfare Centres, and to Mrs Eastham and Miss MacGilley who took the swabs there; to Dr W. Howard Hughes, Dr W. G. Booth, and Dr K. Hart for arranging co-operation of the Ealing Public Health Department; to the Ealing midwives who collected the swabs from the domiciliary-delivered babies; to members of the Wright-Fleming Institute technical staff.

Also, I am grateful to the following organizations for personal grants while conducting the study: The United States Educational Commission in the United Kingdom for a Fulbright Scholarship, 1951–53; The University of California for a grant from the Student Aid Fund; Sigma Delta Epsilon for a Fellowship Award.

We studied the spread of influenza in the community between 1993 and 2009 using primary-care surveillance data to investigate if the onset of influenza was age-related. Virus detections [A(H3N2), B, A(H1N1)] and clinical incidence of influenza-like illness (ILI) in 12·3 million person-years in the long-running Royal College of General Practitioners-linked clinical-virological surveillance programme in England & Wales were examined. The number of days between symptom onset and the all-age peak ILI incidence were compared by age group for each influenza type/subtype. We found that virus detection and ILI incidence increase, peak and decrease were in unison. The mean interval between symptom onset to peak ILI incidence in virus detections (all ages) was: A(H3N2) 20·5 [95% confidence interval (CI) 19·7–21·6] days; B, 18·8 (95% CI 15·8·0–21·7) days; and A(H1N1) 17·0 (95% CI 15·6–18·4) days. Differences by age group were examined using the Kruskal–Wallis test. For A(H3N2) and A(H1N1) viruses the interval was similar in each age group. For influenza B there were highly significant differences by age group (P = 0·0001). Clinical incidence rates of ILI reported in the 8 weeks preceding the period of influenza virus activity were used to estimate a baseline incidence and threshold value (upper 95% CI of estimate) which was used as a marker of epidemic progress. Differences between the age groups in the week in which the threshold was reached were small and not localized to any age group. In conclusion we found no evidence to suggest that influenza A(H3N2) and A(H1N1) occurs in the community in one age group before another. For influenza B, virus detection was earlier in children aged 5–14 years than in persons aged ⩾25 years.

During the outbreak of influenza due to A (H3N3) viruses in Finland in 1985/6 virus pairs were isolated from the same clinical specimens in embryonated hens' eggs (CE) and in canine kidney cell cultures (MDCK). Some of these isolates, the E and M pairs, were distinguished by their reactions in haemagglutination inhibition (HI) tests carried out using polyclonal antisera, and by receptorbinding properties, as evidenced by differences in their elution activity from erythrocytes. Passage of the E- and M-virus isolates in the foreign host affected their serological characteristics, but the E virus did not convert to an M-like virus and the M virus did not convert to an E-like virus. Returning the viruses to grow in the host used for their isolation changed the serological reactions so that they were once more close to the reactions of the original isolates. This contrasts with the changes in receptor-binding properties. Rapid elution from hen erythrocytes, which has been described as a property of viruses binding to the SAα2,3Gal sequence in preference to SAα2,6Gal, characterized the virus passages grown solely in MDCK cell cultures. Cultivation of the M virus in CE, at any stage of its passage history, made the virus irreversibly incapable of elution. The M virus was more sensitive than the E virus to HI antibodies against heterologous viruses of the H3N2 subtype, and, when used as an antigen in HI serology, it more frequently (90% vs. 69%; P < 0·01) detected diagnostic antibody responses in patients infected with viruses of this subtype in 1985/6. Use of antigens with a different passage history in HI serology provided evidence that this superiority, which may be due to the ability of the virus to pick out anamnestic antibody responses, is unrelated to the receptor-binding peculiarity of the M virus under consideration. The results support the concept that the host cell can select a diversity of virus variant subpopulations from a single clinical specimen during isolation and subsequent cultivation procedures. Moreover, the MDCK-grown influenza viruses may correspond better than the egg-grown isolates to the natural epidemic viruses.

Eighty prostitutes wore tested by solid-phase radioimmunoassay for serum markers of hepatitis B virus (HBV). Of 8 (10%) with hepatitis B surface antigen (HBsAg), 6 (75%) also had hepatitis Be antigen (HBeAg). Antibodies to HBsAg (anti-HBs) and to hepatitis B core antigen (anti-HBc) were found in 52 (65%). Antibodies to HBeAg (anti-HBe) were positive in 32 (40%). Anti-HBc alone was found in 5 (6%) and anti-HBs alone in 2 (2%). Sixty-seven (84%) were positive for at least one HBV marker and 13 (16%) were still susceptible to infection. Hepatitis B markers were more prevalent in prostitutes than in the normal Spanish population. Age, a history of sexually transmitted diseases (STD), drug abuse and promiscuity are factors which were highly related to hepatitis B markers. We concluded that screening prostitutes for the presence of markers and vaccinating those who are negative would be worth while.

A modified haemagglutination inhibition test for rubella antibodies, using standardized freeze-dried reagents, was developed and compared with haemagglutination inhibition tests using fresh erythrocytes. This comparison was made in collaboration with six European laboratories. A total of 4205 serum samples were tested. The results show that:

(1) Sensitivity and reliability of the modified test are good;

(2) the modified test can be performed in glass tubes as well as in polystyrene microtitration plates.