1. Two herds of cows were divided into two groups for winter feeding. One group was given the usual ration of hay, roots and “concentrates”, the other was fed on a similar diet in which part of the hay and concentrates was replaced by artificially dried grass.

2. The carotene content of the butterfat in the control group fell steadily from 0·8 mg. per 100 g. of fat to about 0·2 mg. between October and March. That of the group to which dried grass was given did not fall below 0·5 mg. per 100 g. of fat.

3. The milks from the two groups were employed in a nutritional investigation on the boys of two institutions. During a “fore-period” from July until the end of September, the boys received the ordinary milk of the herd as part of their diet. They were then divided into two groups which, during the experimental period from October until March received the “winter” or the dried grass “summer” milk respectively. Then followed an “after-period” during which all the boys received the mixed milk of the herds, then out at pasture. The composition of the basal diet of the boys at these institutions was known. Boys attending an elementary school in the vicinity of one institution were also investigated in a similar experiment but no details of their home diet were obtained.

4. Excluding children whose records were incomplete there were 159 in the group on “winter” milk, and 163 in that receiving “summer” milk.

5. Periodically records of height, weight, and chest measurement were made. All the boys were under medical supervision.

6. Statistical examination of the results fails to show that the artificially produced “summer” milk exerted a beneficial effect detectable by the improvement in growth or general condition of health.

7. The most probable explanation is that the basal diets of the two institutions were already adequate in respect to carotene and vitamin A.

8. The variations exhibited by the records of the groups provide another example of the very great difficulty of eliminating or adequately controlling sources of error in a big-scale nutrition experiment of this type.

Vibrio parahaemolyticus was isolated from 53 out of 584 samples (9·1%) of market fish. All strains were Kanagawa negative and were distributed as follows: sea fish 5 out of 370 samples (1·4%), shellfish 48 out of 214 samples (22·4%). Other fish spoilage microflora recovered were: Alcaligenes faecalis, Pseudomonas aeruginosa, Proteus vulgaris, Aeromonas spp. and Vibrio alginolyticus. Total aerobic counts and coliform counts per gram for the lake fish ranged from 2·6 × 102 to 6·6 × 107 and 10 to 1·0 × 102, respectively. Those from marine fish ranged from 1·0 × 105 to 8·8 × 105 and 2·0 × 103 to 1·6 × 104, respectively. Counts for marine fish gills alone ranged from 1·4 × 105 to 3·4 ×108 and 7·2 × 102 to 1·4 × 107, respectively. No hightemperature (44°) coliforms were recovered from either lake or marine samples.

The original method for molecular typing of E. coli strains was developed using the polymorphism in chromosomal sequences of bacterial interspersed mosaic elements (BIMEs) detected by multiplex PCR and analysed by AFLP assay. The applicability of the method in the epidemiology of E. coli was tested on a group of 524 strains of human and veterinary origin. In the studied group 18 different genotypes were detected. Significant differences were found in the frequencies of the genotypes among various groups of strains, suggesting the method could be a promising tool in the epidemiology of E. coli.

The research which follows was undertaken with the object of determining how far the neutral-red reaction described by Rothberger could be utilised for the purpose of detecting Bacillus coli in water-supplies.

Previous estimates of the incidence of glandular fever vary widely. Reasons for this are suggested. The present investigation was designed to show the incidence of cases of glandular fever presenting to doctors in certain general communities near Portsmouth in 1962–63.

The overall incidence in these areas during the year was found to be 38 per 100,000 population; this amounts to an average of one case annually in a medium-sized general practice. The incidence appeared to be lowest in a council housing estate. Glandular fever was not common in children, although it was frequently diagnosed on clinical grounds.

The ways in which cases of glandular fever might be missed in a survey such as the present one are discussed. It is thought that many patients may become ill but not consult their doctors. Truly subclinical glandular fever, however, is thought to be infrequent.

We investigated an unprecedented outbreak of fulminant hepatitis B virus (HBV) that occurred in Modasa, Gujarat (India) in 2009. Genomic analysis of all fulminant hepatic failure cases confirmed exclusive predominance of subgenotype D1. A1762T, G1764A basal core promoter (BCP) mutations, insertion of isoleucine after nt 1843, stop codon mutation G1896A, G1862T transversion plus seven other mutations in the core gene caused inhibition of HBeAg expression implicating them as circulating precore/BCP mutant virus. Two rare mutations at amino acids 89 (Ile→Ala) and 119 (Leu→Ser) in addition to other mutations in the polymerase (pol) gene may have caused some alteration in either of four pol gene domains to affect encapsidation of pregenomic RNA to enhance pathogenicity. Sequence similarity among patients' sequences suggested an involvement of a single hepatitis B mutant strain/source to corroborate the finding of gross and continued usage of HBV mutant-contaminated syringes/needles by a physician which resulted in this unprecedented outbreak of fulminant hepatitis B. The fulminant exacerbation of the disease might be attributed to mutations in the BCP/precore/core and pol genes that may have occurred due to selection pressure during rapid spread/mutation of the virus.

Glasgow (Scotland's largest city) has a high prevalence of injecting drug use and has one of the highest prevalences of hepatitis C virus (HCV) infection in injecting drug users (IDUs) in Western Europe. HCV prevalence data from surveys of Glasgow's IDUs from 1990 to 2007 were utilized and a model was applied that described the prevalence of HCV as a function of the rate (force) of infection. Force-of-infection estimates for HCV that may vary over time and injecting career length over a range of variables were investigated. New initiates to injecting were found to be at increased risk of HCV infection, with being recruited from a street location and reporting injecting in prison leading to a significant increase in the risk of infection in new initiates. These results indicate areas of importance for the planning of public health measures that target the IDU population.

Twelve British isolates of leptospira belonging to the Sejroe serogroup were examined using a series of six factor sera prepared by a number of different absorption methods. Ten of the isolates were identified as Leptospira interrogans serovar hardjo and two as L. interrogans serovar saxkoebing. These isolates had previously been identified using the cross agglutination absorption method.

Mice, birds (chicks, quail) and fish (rudd, goldfish) killed shortly after receiving 1300–2000 spores of Clostridium botulinum per os were incubated, usually at 23 °C for 7 days. A 10% (w/v) homogenate of each rotting carcass was then prepared, sterilized by membrane filtration, and assayed for toxin.

In mouse carcasses a type C strain of C. botulinum usually produced > 2 × 105 mouse intraperitoneal LD/g; in fish carcasses it usually produced less - often much less - than 2 × 104 LD/g. Avian carcasses appeared to be intermediate between those of mice and fish in their ability to support toxigenesis. A type E strain of C. botulinum, unlike type C. produced toxin equally well in fish and mouse carrion, usually at a concentration of between 2 × 104 and 2 × 105 LD/g.

1. Faeces from apparently healthy Bantu children from schools in Soweto township near Johannesburg were examined eight times at fairly regular intervals over a period of 1 year.

2. Only fifty-five children were present for all eight investigations and, of these, 36·4% yielded salmonellae and 9·1% shigellae. Taking the group as a whole, 26·2% of the children had salmonella infections and 6·2% shigella infections.

3. Parasites were shown to be present in sixty-four of the 130 children during the period of the investigation.

4. As in other surveys, there were more isolations in summer than in winter.

5. S. labadi and S. typhimurium were most frequently isolated, with the group B–E constituting 75% of the total isolations. S. typhi, S. paratyphi A, B and C were not found.

6. Water supplied to each house by the Johannesburg municipality was of good quality, yet it did not affect the incidence of salmonellosis and shigellosis.

7. In spite of better socio-economic conditions the incidence of salmonellosis is comparable to the two previously mentioned surveys. These findings indicate a lack of instruction on personal hygiene and the importance of public health measures.

During the period 1961–71 of 1785 viruses isolated from patients in the general population 503 (28%) were rhinoviruses, 465 (26%) influenza viruses, 248 (14%) enteroviruses, 234 (13%) herpes simplex virus, 132 (7%) parainfluenza viruses, 129 (7%) adenoviruses and 49 (3%) respiratory syncytial virus. Also isolated were 18 strains of mumps virus, 7 coronaviruses and 295 streptococci of groups A, C or G.

Fluctuations were observed in the frequency with which respiratory syncytial virus, parainfluenza virus type 2, and the adenoviruses were isolated over the 10-year period.

Influenza viruses types A and B, parainfluenza viruses types 1 and 2, respiratory syncytial virus, adenoviruses types 3, 4, 6, 7 and 21, and many enteroviruses were all associated with outbreaks.

Infections with influenza viruses A and B and parainfluenza viruses types 1 and 2 came during the winter, whereas those with parainfluenza virus type 3, enteroviruses, and rhinoviruses were more frequently seen in the summer and early autumn.

1. Antisera, made against crystalline egg-albumin, have been examined by titrating a constant amount of antiserum against falling amounts of the antigen (the usual Dean and Webb method), and also by the reverse procedure in which the amount of antigen was constant and that of antiserum varied. The ratios by the two methods were never found to agree; nevertheless, in the majority of cases the relationship which the ratio by one method bore to the ratio by the other method was of the same order, and it is possible that this relationship is constant for crystalline egg-albumin and its antisera.

2. The conclusions reached in my previous work (1931) require modification, because in those experiments insufficiently extensive ranges were used and as a result it was found that when varying amounts of anti-horse serum were titrated against a fixed amount of antigen, particulation was quickest in the tube containing most antiserum.

3. Titrations by the reverse method over a fairly considerable range have provided evidence that the proportions of crystalline egg-albumin and a given homologous antiserum favourable for the most rapid particulation are constant despite absolute quantitative changes. The proportions in which these reagents particulate most rapidly are similarly constant in titrations by the usual Dean and Webb method.

4. Why the two methods of titration give different results I am unable to explain, but the point of optimal particulation found by the Dean and Webb method probably coincides with the point of neutrality of antigen and antibody. Since in the Ramon (1923) method of titrating diphtheria toxin and antitoxin the reverse method, with constant antigen and varying antiserum, is used, the work reported here suggests that the determination of the relationship to each other and to animal values of the results of titrations of toxin and antitoxin by both methods might yield helpful information.

5. Some points of practical importance in the performance of optimal proportions titrations are appended.

Optimum forms of moving averages are derived for the estimation of LD 50 in the situation where no assumptions are made about the form of the dose-response distribution. The theory is also applied to uses of moving averages based on the angular transformation of the percentage response. A numerical example illustrates this application, and its results are compared with the corresponding probit and logit estimates.

A series of 35 unselected cattle tested with synthetic medium tuberculin and synthetic medium johnin was subjected to post-mortem examination. In five instances (14·3 %) avian strains of full virulence for the usual experimental animals were recovered by the inoculation of guinea-pigs with glandular suspensions or by cultural methods used for the isolation of Johne's bacillus: in two of these cases an avian type was isolated from the glands of the alimentary tract and a bovine type from the thoracic glands. In addition there were five cases (14·3%) in which evidence of avian infection was not complete. From one a strain was obtained which was culturally identical with an avian type, but it was almost completely avirulent for laboratory animals. In two, acid-fast bacilli were seen in smears from the thoracic and mesenteric glands respectively, while in two, completely calcified glands were observed which were typically tuberculous, but were devoid of acid-fast bacilli (microscopical examination of smears and sections). Cultures from the organs of guinea-pigs inoculated with glandular suspensions from the four last-mentioned cases failed to grow tubercle bacilli. In these circumstances the evidence that the infection was of the avian type is largely presumptive, but the nature and extent of the lesions suggests that such may have been the case.

With, regard to the tuberculin and johnin tests, clear cut reactions to johnin were obtained in seven instances, a doubtful reaction in one and negative reactions in two. One-half of the animals were also positive to tuberculin.

Preliminary evidence suggests that direct poultry contact may play a lesser role in transmission of avian influenza A(H7N9) than A(H5N1) to humans. To better understand differences in risk factors, we quantified the degree of poultry contact reported by H5N1 and H7N9 World Health Organization-confirmed cases. We used publicly available data to classify cases by their degree of poultry contact, including direct and indirect. To account for potential data limitations, we used two methods: (1) case population method in which all cases were classified using a range of sources; and (2) case subset method in which only cases with detailed contact information from published research literature were classified. In the case population, detailed exposure information was unavailable for a large proportion of cases (H5N1, 54%; H7N9, 86%). In the case subset, direct contact proportions were higher in H5N1 cases (70·3%) than H7N9 cases (40·0%) (χ2 = 18·5, P < 0·001), and indirect contact proportions were higher in H7N9 cases (44·6%) than H5N1 cases (19·4%) (χ2 = 15·5, P < 0·001). Together with emerging evidence, our descriptive analysis suggests direct poultry contact is a clearer risk factor for H5N1 than for H7N9, and that other risk factors should also be considered for H7N9.

A total of 46 strains of Salmonella isolated from patients with sporadic diarrhoea or involved in foodborne outbreaks were analysed by PCR for genus identification and serotyping. Subtyping was performed using pulsed-field gel electrophoresis (PFGE) and multiple amplification of phage locus typing (MAPLT) for seven variable loci. Bacteria were identified as belonging to serotype Enteritidis (33 strains; 71·7%) or Typhimurium (13 strains; 28·3%). A high similarity coefficient (94·6%) was observed in the Salmonella Enteritidis group for which were found three related PFGE profiles and only one MAPLT; strains representing profile PA/P1/MI were prevalent (27; 81·8%). Two Salmonella Typhimurium isolates were untypeable by PFGE. The remaining 11 strains had eight PFGE and three MAPLT profiles. The discriminatory power of MAPLT was lower than that of PFGE. Salmonella Enteritidis of clonal nature is predominant in Paraná State, with the most prevalent profile PA/P1/M1 associated with sporadic diarrhoea and with seven of nine reported outbreaks. In conclusion, PFGE shows higher discriminatory power among Salmonella strains.

In recent studies on experimental epidemiology, and especially in a series of reports by Webster (1922, 1923 a, b, c, d, e, f and g), attempts have been made to standardise certain of the factors concerned in the spread of bacterial infection among mice. One such factor is dosage, to which great importance has been attached by Amo⋅s (1922 a and b) and also, though to a somewhat less extent, by Webster, whose later work leads him to emphasise the importance of host-susceptibility in determining the form of the epidemic wave. Webster would appear to regard variations in dosage as decisive, in the sense that an effective dose must be applied; but once the critical limit of dosage is exceeded he would give first place to host-susceptibility in determining the subsequent course of events.

We aimed to determine the seroprevalence of poliovirus antibody in Korea by using the cell culture neutralization method recommended by the WHO. A total of 500 sera collected from children at eight primary schools in Kyunggi province were used for this study. We found that 82·2% of children were positive for all three types of poliovirus and antibody-positive rates for types I, II and III were 94·4, 96·6 and 86·8% respectively, indicating that seropositive rates for types I and II were considerably higher than for type III (P<0·0001). This result implies that the type III component of the oral polio vaccine should be evaluated further. Although a greater number of children, including young infants, need to be tested for seroprevalence, this study still provides us with valuable information on the effectiveness of vaccination against polioviruses in Korea.

A serological survey for brucella antibodies has been carried out in Northern Ireland in an attempt to assess the effects of the brucellosis eradication programme in cattle which has been in progress since 1959. One thousand eight hundred and ninety four sera from blood donors, from farmer's lung tests, and from various groups occupationally exposed to cattle were examined by the serum agglutination test, the anti-human globulin (A.H.G.) (Coombs) test and the complement-fixation test.

The incidence of brucellosis in Northern Ireland is now less than it was 20 years ago, but is similar to that reported in a recent survey in England. It now appears that the principal method of transmission of brucellosis in the province is by occupational exposure rather than by drinking infected milk. Though it may be too early to make a serological assessment of the effects on human infections of brucellosis eradication in cattle, this survey provides a basis for future evaluation.

We thank Prof. O. L. Wade, Prof. P. C. Elmes and Dr W. R. Kerr for their encouragement and helpful advice; the Medical Officers of Health in Antrim, Armagh, Down and Fermanagh, Londonderry, and Tyrone, and in Belfast and Londonderry County Borough for help in obtaining blood samples; Dr M. C. Huth of the Northern Ireland Blood Transfusion Service, for sera; Dr D. W. R. Mackenzie and Miss H. E. Cairns for sera from the Mycology Diagnostic Laboratory; Dr J. H. Connolly for sera from the Virus Reference Laboratory, and for helpful advice; the farm workers and veterinary surgeons for volunteering blood samples; the technical staff of the Veterinary Research Laboratories for carrying out the tests.

The relationship between multiplicity of infection and the yield of organisms and of polysaccharide was studied in BHK 21 cells infected with TRIC organisms. Although an increase in themultiplicity of infection resulted in an increase in the absolute number of organisms per culture, there was a decrease in relation to the number of infecting organisms. The amount of polysaccharide produced was independent of multiplicity of infection; it was not limited by the concentration of glucose in the medium. Polysaccharide leaked from cells and was slowly broken down in the culture medium.