1. The membrane piece technique for in vitro titrations of the infectivity of influenza virus is described. Rectangles of shell, about 8 × 25 mm., with the chorio-allantoic membrane still attached (membrane pieces) are cut from thirteenth-day fertile eggs. One piece in a test-tube with glucose-buffered salt solution forms an individual assay unit. Five or more tubes are inoculated with each virus dilution. After incubation at 37° C. for 72 hr., with agitation for the first 24 hr. the fluid in each tube is tested for haemagglutinins. From the results at each dilution, an estimate of the 50% membrane piece (MP50) infectivity titre is obtained.

2. Six hundred assay units, with pieces cut from twenty eggs, can be set up by two workers in 1 hr. and used for titration of between three and twenty-four individual virus preparations, depending on the reliability desired for the 50% end-point estimates.

3. With the D.S.P. and PR 8 strains of influenza A virus, the MP50 titres parallel the EID50 titres from egg titrations, but are eight times and twenty times lower, respectively. The MP50: EID50 ratio is the same for various preparations of the same strain, including standard allantoic fluid and chorio-allantoic membrane virus, incomplete virus, and inactivated (heated) allantoic fluid virus. Preliminary experiments with Lee influenza B virus show that slightly different experimental conditions are required, and the MP50 titres are about fifty times less than the EID50 titres.

4. Consistent results have been obtained on titration of samples of the same virus preparation on a number of occasions over a period of several months.

5. A large number of membrane pieces can be used to test each virus dilution, and sampling variations in the MP50 estimates thus made quite small. Statistical data on the reliability of a 50 % titration result, and on the minimum significant differences between two end-points, are given for different values of n, the number of membrane pieces used to test each virus dilution, and of d, the log dilution step.

We are grateful to Mr J. Collins for invaluable technical assistance, and also to Miss I. Allen for help with the computations.

Pyocine typing was used for the characterization of 134 Pseudomonas aeruginosa strains isolated from bovine mastitis. The scheme of Gillies & Govan (1966) was adopted with some modifications, and the procedure gave 89·6% typability. Pyocine type 1 strains were most commonly encountered and were followed in frequency by types 10 and 3. The introduction of two additional indicator strains allowed for division of these types into subtypes.

In spite of some limitations, discussed in the paper, the pyocine typing scheme proved to be useful in ‘marking’ P. aeruginosa strains and in following their association with bovine mastitis in various herds.

To investigate the frequencies of dendritic cells (DCs) and Toll-like receptor 3 (TLR3) in neonates of HBsAg-positive mothers with different HBV serological profiles, we conducted a study in Taiyuan, China. The study included 144 HBsAg-positive mothers and their neonates. The frequencies of DCs and TLR3 were determined using four-colour flow-cytometric analysis. DC and TLR3 frequencies were not related to HBV intrauterine transmission, maternal HBeAg positivity, maternal HBV DNA positivity and HBeAg/HBV DNA double-positivity. The plasmacytoid dendritic cell (pDC) frequencies in neonates whose maternal HBV DNA was >5 × 107 copies/ml decreased significantly compared to that in neonates whose maternal HBV DNA was ⩽5 × 107 copies/ml (Z = − 2·170, P = 0·03) or whose maternal HBV DNA was negative (Z = − 1·981 P = 0·048). This study suggests that neonatal pDC frequencies decrease when maternal HBV DNA loads are >5 × 107 copies/ml.

A review of 194 cases of enteric infection in Scotland during 1967–74, is reported. Diagnosis was confirmed by the laboratory isolation of Salmonella typhi (64 cases), S. paratyphi A (3) and S. paratyphi B (127), from blood or faeces; 174 persons were clinically ill and 20 were symptomless infections.

Most patients (81·0%) were under 35 years of age, with the highest incidence occurring among young adults of 15–24 years, many of whom had been travelling overseas. One-third of all cases (65) were imported infections; the remaining 129 patients had not been outside the United Kingdom. A significantly greater proportion of typhoid infection (54·7%) was contracted overseas, in contrast to paratyphoid B with only one-fifth of cases (21·2%) being imported; all three cases of paratyphoid A were imported. The geographic distribution of origin of imported infections is discussed, along with the frequency of organisms belonging to different phage types.

Two deaths occurred, one of which was the result of complications of paratyphoid fever. All other patients responded well to treatment, although two persons continued to excrete and became chronic carriers.

A few examples are given of episodes of particular epidemiological interest.

It is expected that in future years there will be a continued increase in the proportion of imported infections as more persons travel overseas, concurrent with the continuing decline in the number of chronic carriers resident in the British Isles.

Multidrug-resistant isolates of Acinetobacter baumannii from New York City generally belong to one of three ribotypes. To assess the accuracy of ribotyping, the relatedness of representative isolates was further assessed by rep-PCR, pulsed-field gel electrophoresis (PFGE), and DNA sequencing of five genes potentially associated with antimicrobial resistance (ampC, ompA, adeB, adeR, and abeM). The isolates fell into several major groups. The first group shared the same ribotype and had common mutations affecting OmpA, AdeR, and AbeM, but consisted of two subtypes with distinctive rep-PCR and PFGE patterns and ampC mutations. The second and third groups shared common alterations in OmpA, AdeR, and AbeM, but had distinct ribotype, rep-PCR, and PFGE patterns. The resistant isolates were unrelated to the β-lactam susceptible isolates. Many of the resistant strains shared OmpA and AdeB patterns observed in several European clonal groups. Further development of a multilocus sequencing typing scheme will help determine if multidrug-resistant isolates from diverse geographic areas are indeed ancestrally related.

During commercial processing of broiler chickens, injection of polyphosphate (Puron 604 or 6040) resulted in microorganisms being added to the deep breast muscle. The level of contamination was related to the microbiological condition of the injection solution.

Injection of polyphosphate had no effect on the shelf-life of fresh chilled carcasses held at 1° or 10°C but changes were observed in the growth rate of microorganisms in the deep muscle and in the composition of the muscle microflora following storage.

Cross-contamination of carcasses and the transfer of organisms from the skin to the deep muscle during injection was demonstrated with a marker strain of Clostridium perfringens. However, both processes were influenced by the number of marker organisms applied initially to the skin.

The above findings are discussed in relation to the possible behaviour of any food poisoning bacteria present.

Only 2 out of 71 German patients infected with rotavirus (3%) and 8 out of 147 German control patients (5%) showed serum antibody to the new serotype 8 rotavirus. Such antibody was detected in the sera of 232 of 870 Ecuadorian children (27%). Twelve Ecuadorian sera showed neutralizing activity only against serotype 8 and not to the other serotypes (1–4) tested, indicating that human serotype 8 rotavirus circulates in South America.

1. The 6 hr. soluble antigen production test for comparing the infectivity of influenza virus preparations is described in detail. Dilutions of the preparations are inoculated intra-allantoically into groups of fertile eggs, and after 6 hr. of incubation the amounts of soluble antigen formed in their chorio-allantoic membranes are determined. Reproducible results can be obtained.

2. The similar test, in which haemagglutinins in the chorio-allantoic membranes are measured 6 hr. after inoculation of seed virus, is less accurate and less sensitive.

3. Eggs of different ages of incubation form different amounts of soluble antigen in their chorio-allantoic membranes in 6 hr. when inoculated with the same amounts of virus.

In a recent communication (Penfold 1911) I described experiments with three organisms, B. coli Escherich, B. enteritidis Gaertner and B. Grünthal, showing that limitation or complete abolition of certain gas-forming powers normally possessed by these organisms, could be brought about by their growth on chloracetic acid-agar, and further, that in the case of the latter organism, resistance to this medium was associated with such limitation or abolition.

Inadequate notification is a recognized problem of measles surveillance systems in many countries, and it should be monitored using multiple data sources. We compared data from three different surveillance sources in 2007: (1) the sentinel surveillance system mandated by the Act on Prevention of Infectious Diseases and Medical Care for Patients Suffering Infectious Diseases, (2) the mandatory notification system run by the Aichi prefectural government, and (3) health insurance claims (HICs) submitted to corporate health insurance societies. For each dataset, we examined the number of measles cases by month, within multiple age groups, and in two categories of diagnostic test groups. We found that the sentinel surveillance system underestimated the number of adult measles cases. We also found that HIC data, rather than mandatory notification data, were more likely to come from individuals who had undergone laboratory tests to confirm their measles diagnosis. Thus, HIC data may provide a supplementary and readily available measles surveillance data source.

It has been shown that the L-form of Streptobacillus moniliformis is filerable through gradocol membranes which retain the bacillary A-form completely. From the filtration analysis carried out as described it would appear that the particle size of the L-form of Strep. monilifprmis ranges with the larger viruses while the bacillary A-form ranges with Bact. prodigiosum.

Two new Salmonella types are described. S. minnesota was isolated from a turkey. Its antigenic formula is XXI: b ⇋ enx. S. worthington was found both in a chicken and in a turkey. Its antigenic formula is I XIII XXIII: Iw ⇋ z…. Transfers of each type have been deposited in the National Collection of Type Cultures of Great Britain and in the American Type Culture Collection.

Twenty–four cultures comprising 20 clinical isolates of ‘Klebsiella aerogenes’ from two hospitals, a reference strain of ‘K. aerogenes’ and the type strains of three other Klebsiella species, were characterized by one–dimensional sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE) of whole–cell proteins. The protein patterns were highly reproducible and were used as the basis of a numerical analysis which divided the clinical isolates into 12 protein types. Comparison with established typing methods indicated that the level of discrimination of SDS–PAGE was similar to that achieved with conventional typing methods but the strains were grouped differently. Protein typing sub–divided five serotype K3 isolates that could also be distinguished by phage typing. Conversely, three strains of protein type 11 were clearly distinguishable by both serotyping and phage typing. We conclude that high–resolution SDS–PAGE of proteins provides an effective adjunct to other methods for typing isolates of ‘K. aerogenes’.

This study was performed to investigate space–time patterns of Campylobacter spp. colonization in broiler flocks in Norway. Data on the Campylobacter spp. status at the time of slaughter of 16 054 broiler flocks from 580 farms between 2002 and 2006 was included in the study. Spatial relative risk maps together with maps of space–time clustering were generated, the latter by using spatial scan statistics. These maps identified the same areas almost every year where there was a higher risk for a broiler flock to test positive for Campylobacter spp. during the summer months. A modified K-function analysis showed significant clustering at distances between 2·5 and 4 km within different years. The identification of geographical areas with higher risk for Campylobacter spp. colonization in broilers indicates that there are risk factors associated with Campylobacter spp. colonization in broiler flocks varying with region and time, e.g. climate, landscape or geography. These need to be further explored. The results also showed clustering at shorter distances indicating that there are risk factors for Campylobacter spp. acting in a more narrow scale as well.

Since the incursion of influenza A(H1N1)pdm09 virus in 2009, serosurveillance every year of the Norwegian pig population revealed the herd prevalence for influenza A(H1N1)pdm09 (HIN1pdm09) has stabilised between 40% and 50%. Between 30 September 2009 and 14 September 2017, the Norwegian Veterinary Institute and Norwegian Food Safety Authority screened 35,551 pigs for antibodies to influenza A viruses (IAVs) from 8,636 herds and found 26% or 8,819 pigs' sera ELISA positive (titre ≥40). Subtyping these IAV antibodies from 8,214 pigs in 3,629 herds, by a routine haemagglutination inhibition test (HAIT) against four standard antigens produced 13,771 positive results (HAIT titre ≥40) of binding antibodies. The four antigen subtypes eliciting positive HAIT titre in descending frequencies were immunogen H1N1pdm09 (n = 8,200 or 99.8%), swine influenza A virus (SIVs) subtypes swH1N1 (n = 5,164 or 62%), swH1N2 (n = 395 or 5%) and swH3N2 (n = 12 or 0.1%). Of these 8,214 pig pigs sera, 3,039 produced homologous HAIT subtyping, almost exclusively immunogen H1N1pdm09 (n = 3,026 or 99.6%). Using HAIT titre of pig and herd geometric mean titre (GMT) as two continuous outcome variables, and with the data already structured hierarchically, we used mixed effects linear regression analysis to investigate the impact of predictors of interests had on the outcomes. For the full data, the predictors in the regression model include categorical predictors antigen subtype (H1N1pdm09, swH1N1, swH1N2 & swH3N2), and production type (sow herd or fattening herd), ordinal predictors year (longitudinally from 2009 to 2017) and number of antigens in heterologous reactions (1, 2, 3, 4) in the same pig serum. The last predictor, the proportion of HAIT positive (antigen specific) in tested pigs within the herd, was a continuous predictor, which served as a proxy for days post-infection (dpi) or humoral response time in the pig or herd. Regression analysis on individual pig HAIT titres showed that antigen as a predictor, the coefficient for immunogen H1N1pdm09 was at least fourfold higher (P < 0.001) than the three SIVs antigen subtypes, whose much lower coefficients were statistically no different between the three SIVs antigen subtypes. Correspondingly, for herd GMT, immunogen H1N1pdm09 was 28–40-fold higher than the three SIVs antigen subtypes. Excluding the HAIT data of the three SIVs antigen subtypes, regression analysis focusing only on immunogen H1N1pdm09 increased greatly the coefficients of the predictors in the models. Homologous reactions (99.6% H1N1pdm09) have lower HAIT titres while the likelihood of the number of antigens involved in HAIT heterologous reactions in a single pig serum increased with higher HAIT titres of immunogen H1N1pdm09. For predictor ‘production’, sows and sow herds had higher HAIT titres and GMT compared to fattening pigs and fattening herds respectively. Herds with ‘higher proportion of pigs tested positive’ also had higher HAIT titre in the pig and herd GMT.

Pneumonia causes significant morbidity and mortality in Aboriginal populations in Australia's Northern Territory (NT). Kava, consumed in Arnhem Land since 1982, may be a risk factor for infectious disease including pneumonia. A case–control study (n=115 cases; n=415 controls) was conducted in 7001 Aboriginal people (4217 over 15 years). Odds ratios (OR) were calculated by conditional logistic regression with substance use and social factors as confounders. Pneumonia was not associated with kava use. Crude OR=1·26 (0·74–2·14, P=0·386), increased after controlling for confounders (OR=1·98, 0·63–6·23, P=0·237) but was not significant. Adjusted OR for pneumonia cases involving kava and alcohol users was 1·19 (0·39–3·62, P=0·756). In communities with longer kava-using histories, adjusted OR was 2·19 (0·67–7·14, P=0·187). There was no kava dose–response relationship. Crude ORs for associations between pneumonia and cannabis use (OR=2·27, 1·18–4·37, P=0·014) and alcohol use (OR=1·95, 1·07–3·53, P=0·026) were statistically significant and approached significance for petrol sniffing (OR=1·98, 0·99–3·95, P=0·056).

We assessed the role of tuberculosis (TB) disease and HIV infection on the level of physical activity. A combined heart rate and movement sensor was used to assess habitual physical activity in TB patients and non-TB controls. The association between sputum-negative TB, sputum-positive TB, HIV and physical activity estimates were assessed in multivariable linear regression models adjusted for age, sex, haemoglobin and alpha-1-acid glycoprotein (AGP). Sputum-positive [eB 0·43, 95% confidence interval (CI) 0·29–0·64] and sputum-negative (eB 0·67, 95% CI 0·47–0·94) TB as well as HIV infection (eB 0·59, 95% CI 0·46–0·75) were associated with reduced activity compared to controls. Anaemia accounted for a substantial part of the effects of HIV, while elevated AGP primarily mediated the TB effect. The level of physical activity is highly influenced by TB and HIV, and mainly mediated through anaemia of infection and associated with elevated acute phase response.

The following observations upon the Natural History of Epidemic Diarrhoea were made in Mansfield during the summer and autumn of 1908. The fact that at the time the writer was engaged in preparing a paper—to which the present paper is to some extent complementary—upon the epidemiological relations of season and disease, lent special interest to the enquiries regularly made from the Health Department of this town into the circumstances attending fatal attacks of diarrhoea. Early in the season a more than usually extensive enquiry was made into one of these fatal attacks in an area where an outbreak of diarrhoea appeared to be spreading outwards from a group of old privy-middens. To test how far the condemnation of the latter was justifiable another area was taken on the other side of the town, where the houses were newly built and provided exclusively with water-closets; and records, collected by house-to-house visitation, were obtained of all cases of epidemic diarrhoea, whether non-fatal or otherwise, occurring in these localities. The enquiries thus begun were afterwards extended so as to embrace two fairly large districts, a chance of doing this being provided by the opportune postponement of the addition to the department of certain work of inspection which had been impending at the beginning of the summer. These districts were several times revisited and scattered observations were also made throughout the other parts of the town. During 1909, while there was no opportunity of making extended observations, there were valuable opportunities during the course of the routine inspections of the summer of testing and re-testing the principal results obtained during 1908.

Norovirus (NoV) epidemics normally peak in December in Japan; however, the peak in the 2009–2010 season was delayed until the fourth week of January 2010. We suspected intensive hand hygiene that was conducted for a previous pandemic influenza in 2009 as the cause of this delay. We analysed the NoV epidemic trend, based on national surveillance data, and its associations with monthly output data for hand hygiene products, including alcohol-based skin antiseptics and hand soap. The delayed peak in the NoV incidence in the 2009–2010 season had the lowest number of recorded cases of the five seasons studied (2006–2007 to 2010–2011). GII.4 was the most commonly occurring genotype. The monthly relative risk of NoV and monthly output of both alcohol-based skin antiseptics and hand soap were significantly and negatively correlated. Our findings suggest an association between hand hygiene using these products and prevention of NoV transmission.

Strains of Bordetella pertussis in which all the organisms contain agglutinogens 1 and 3 or 1, 2 and 4 are easy to identify as serotypes 1,0,3,0 and 1,2,0,4 respectively; and similarly, stable strains of serotype 1,0,3,4 are occasionally found. During repeated subcultures, passage in vivo, and lyophilization and preservation for many years, these serotypes do not change. Mixing 1,0,3,0 and 1,2,0,4 serotypes and culturing them together in vivo and in vitro produces cultures from which organisms of the same two serotypes can be isolated.

In contrast, strains which type as 1,2,3,4 are often a heterogeneous group. We have attempted to classify these as 'stable', 'variable' and 'mixed' cultures. Some strains comprise organisms all of which contain the four agglutinogens and are as easy to type as the strains described above. These we have called 'stable' 1,2,3,4 strains. Other 1,2,3,4 strains are made up of colonies possessing all four agglutinogens, as shown by agglutinin production, but in amounts varying from day to day so that direct typing is inconsistent. These we have called 'variable' 1,2,3,4 strains. The last category, 'mixed', is made up of organisms most of which give rise to stable 1,2,3,4 cultures; a few of the component organisms, however, have one or two of the four agglutinogens missing. The importance of the 'variable' cultures is emphasized for work on apparent change of serotype, e.g. during infection.