The electrophoretic variations of carboxylesterase B and of esterases A, C and I, the presence of mannose resistant haemagglutinin, α–haemolysin, cytotoxic necrotizing factor type 1 (CNF1) and certain O antigens were compared in 150 strains of Escherichia coli responsible for extra-intestinal infections. Electrophoretic mobilities of outer membrane proteins (OMP) were also studied for strains belonging to O4, O6, O7, O8 and O75 serogroups. Fast migrating allozymes of carboxylesterase B (pattern B1) were correlated with slow migrating allozymes of esterase C, serogroups O7 and O8, lack of virulence factor, and particular OMP patterns, whereas slow migrating allozymes of carboxylesterase B (pattern B2) were correlated with fast migrating allozymes of esterase C, serogroups O2, O4, O6, O18 and O75, virulence factor production, and distinct OMP patterns. Allozymes of esterases A and I were not clearly correlated with the distribution of virulence factors. The pattern B2 was more strongly associated with CNF1 than with α–haemolysin and mannose resistant haemagglutinin. These results substantiate the view that the electrophoretic pattern B2 of carboxylesterase B identified most of the highly pathogenic strains implicated in extra-intestinal infection of humans.

The aim of this cross-sectional study was to identify post-COVID-19 condition (PCC) phenotypes and to investigate the health-related quality of life (HRQoL) and healthcare use per phenotype. We administered a questionnaire to a cohort of PCC patients that included items on socio-demographics, medical characteristics, health symptoms, healthcare use, and the EQ-5D-5L. A principal component analysis (PCA) of PCC symptoms was performed to identify symptom patterns. K-means clustering was used to identify phenotypes. In total, 8630 participants completed the survey. The median number of symptoms was 18, with the top 3 being fatigue, concentration problems, and decreased physical condition. Eight symptom patterns and three phenotypes were identified. Phenotype 1 comprised participants with a lower-than-average number of symptoms, phenotype 2 with an average number of symptoms, and phenotype 3 with a higher-than-average number of symptoms. Compared to participants in phenotypes 1 and 2, those in phenotype 3 consulted significantly more healthcare providers (median 4, 6, and 7, respectively, p < 0.001) and had a significantly worse HRQoL (p < 0.001). In conclusion, number of symptoms rather than type of symptom was the driver in the identification of PCC phenotypes. Experiencing a higher number of symptoms is associated with a lower HRQoL and more healthcare use.

Infusoria have the same bactericidal power as flagellates. Emulsions containing Bacillus typhosus, Vibrio cholerae, V. Dunbar, V. El Tor, B. megatherium and Spirillum volutans, to which Colpoda cucullus is added, are soon cleared. Before the clearage the Colpodae multiply actively.

This bactericidal effect does not depend upon the production of toxic substances by the Infusoria. The fluid obtained from filtered cultures of the Infusoria exerts no bactericidal effect. Only living Colpodae are able to clear the emulsions.

Direct sunlight does not prevent the clearing of the emulsions by the Infusoria, but temperatures below 10°C. and above 30°C. and absence of oxygen (anaerobic culture) are unfavourable to their exerting a bactericidal effect.

The polluted water of the canals of Amsterdam slightly delayed the clearage of the emulsions; the sewage of starch factories and gas factories completely prevented this clearage.

Consequently under natural conditions Infusoria will only play a part in purifying river water (1) if the temperature is above 10° and under 30°C., (2) if the aquatic vegetation is rich enough to supply the necessary quantity of oxygen, (3) if the water is not highly polluted by adjoining factories.

Streptococcus pneumoniae (S. pneumoniae) is one of the most common community-associated pathogens responsible for pneumonia in children. This retrospective study aimed to investigate the molecular characteristics of S. pneumoniae isolated from children with community-acquired pneumonia (CAP) under 5 years in Chengdu, China. Molecular characteristics of S. pneumoniae included serotype and virulence factor performed by using PCR method and sequence types (STs) determined by sequencing seven housekeeping genes. In addition, the potential relationships between molecular characteristics were depicted by minimum spanning tree and correspondence analysis. The prevailing serotypes were 19F (18.52%), 6B (17.59%), 19A (13.89%), 6A (6.48%) and 23F (5.56%) among 108 isolates. The overall coverage rates of 7-valent, 10-valent, 13-valent, 15-valent and 20-valent pneumococcal conjugate vaccines (PCVs) were 47.32, 48.1, 75, 75 and 78.7%, respectively. Meanwhile, the coverage rates of PCV13 among the isolates from CAP patients aged <1 year were high up to 84.2%. MLST analysis results showed that there were 56 different STs identified, of which the dominant STs were ST271 (22.22%) and ST320 (12.04%). Five international clones among STs were observed, including Spain23F‐1, Spain6B‐2, Taiwan19F‐14, Netherlands3‐31 and Denmark14‐32. Additionally, most of the isolates carried ply, psaA, nanA, pavA, piaA and CC271 isolates expressed more of nanA than non-CC271 isolates. Moreover, there were strong relevant relationships among STs, serotypes and virulence factors. Considering serotypes and virulence factors together can be used as the foundation for the formulation of vaccine strategy.

Estimation of the degree of undercount is important for disease surveillance. Capture–recapture techniques are now being used to evaluate the completeness of disease ascertainment. This study estimated the level of under-notification of giardiasis in the Auckland adult population using a capture–recapture method. Two independent datasets of giardiasis cases [ges ]15 years were generated from the 1998–1999 Auckland Giardiasis Study (AGS) case database and cases notified to Auckland Regional Public Health Services (ARPHS) for the same period of time. Cases were matched and under-notification was estimated using a two-sample capture–recapture method. During the 12-month period, 199 cases participated in the AGS and 413 cases were notified to ARPHS. The capture–recapture calculation indicated that only 49% of cases were notified. Under-notification by a factor of 2 obscures the true burden of giardiasis. Socio-economic conditions and water quality may influence disease notification inversely. Capture–recapture techniques are useful in evaluating the completeness of surveillance.

The three experiments with which this report deals were undertaken with the object of re-examining the conversion factor 1600 which had been provisionally allotted by the Second International Conference on Vitamin Standardization (1934) for converting the results of spectrophotometric tests for vitamin A into international units.

We aimed to assess vaccination coverage (VC) in 17-year-old French young adults (YAs) participating in one mandatory Day of Defence and Citizenship (DDC). Between June 2010 and May 2011, YAs participating in 43 randomly selected mandatory sessions of the DDC programme in Poitou-Charentes (France) were asked to provide their personal vaccination record. Tetanus, diphtheria, polio, hepatitis B, Haemophilus influenzae b, pertussis, measles, mumps and rubella vaccination status were assessed at ages 2, 6, 13 and 17 years. Of 2610 participants, 2111 (81%) supplied documents for evaluation. Of these, 1838 (87%, M:F sex ratio 0·96) were aged 17 years (9% of the global population of this age in the area). The assessment of the 17-year-olds demonstrated the following rates of complete vaccination: diphtheria-tetanus-polio 83%; measles, mumps and rubella 83%; pertussis 69%; H. influenzae b 61%; human papillomavirus 47%; and hepatitis B 40%. At age 6 years, only 46% had received two doses of the vaccine against measles. The YAs were not aware of their status but were in favour of vaccination. VC in YAs is insufficient, particularly for hepatitis B, pertussis and measles. Combined vaccines and the simplification of vaccination schedules should improve VC. Preventive messages should focus on YAs.

It having been considered desirable that further experiments upon the range of flight of flies should be carried out, the investigation of the subject was entrusted to Dr E. Hindle and Mr G. Merriman, who are engaged in research in my laboratory. Although the experiments here recorded were carried out under somewhat adverse climatic conditions, they appear of sufficient interest to warrant publication, since the results with regard to the influence of wind seem to run counter to those recorded by previous workers, and also, apart from Hewitt's work referred to below, data have hitherto been wanting in respect of the range of flight of flies (Musca domestica Linn.) in towns. The simple graphic method of recording the results of the flight experiments, which occurred to me during the course of the work, may commend itself to others who may carry out similar investigations in the future.

It might seem very late to suggest, nearly 400 years after the first clinical description of influenza and 54 years after its isolation (reviewed by Stuart-Harris. Schild & Oxford, 1985), that many fundamental questions remain to be answered about the virus itself. However the precise antigenic and biochemical structure of the natural field virus has not been established. If so much remains to be learned concerning the nature of the virion then perhaps it may be less surprising that there are some conflicting theories as regards influenza epidemiology. Such questions are raised in the current volume of the journal where Hope-Simpson & Golubev (pp. 5 54) propose a major role for virus persistence in the human disease and, a lesser role for a linked chain of acute infection spreading influenza around the world (see also Hope-Simpson. 1979: 1981). This would be a minority view of the epidemiology of influenza A at present and is most definitely in conflict with the orthodox idea of person to person spread in an endless chain.

The efficacy of vaccine when time since exposure is prolonged (more than 1 week from onset of illness in the index case) is unknown, but is likely to be significantly lower than human normal immunoglobulin (HNIG). We estimated the number of additional secondary cases that may occur through giving vaccine instead of HNIG to contacts of cases of hepatitis A who are identified more than 1 week after onset in the index case. This was calculated for different levels of vaccine efficacy, assuming HNIG efficacy to be 80–90%. The number of households that need to be treated to prevent one secondary case was calculated using estimates of secondary attack ratios (AR). If more than 1 week has elapsed from onset of illness in the index case, for an average household size of 2·3 people, a vaccine efficacy of 50% and an AR of 10–25%, 8–26 households would need to be treated with vaccine before one additional secondary case would be observed. As UK public health professionals manage around one hepatitis A case per month, it would take from 8 months to over 2 years for them to observe one additional case amongst contacts using vaccine rather than HNIG. It is unlikely that an average practitioner would notice if vaccine were 30% less effective than HNIG. Public health practice and advice to patients and contacts should be based on evidence as well as experience.

From pneumococci a species antigen can be obtained which on injection gives protection against pneumococci of different types.

Species antigen is a somatic constituent of pneumococci and can be obtained in solution free of protein. It may be of carbohydrate nature, but is not derived from the type-specific material.

The bodies of pneumococci contain another substance which on injection opposes species immunization. This opposition factor is closely associated with the protein content.

Inconstant results from injection of preparations containing species antigen are due to the presence of opposition factor in varying amount.

A high degree of species immunity can be secured by the use of species antigen freed from opposition factor.

The infusion of 10 μg of endotoxin lipopolysaccharide from Escherichia coli into the mammary gland of four cows 16 h before inoculation with ureaplasmas did not prevent, or even diminish, the subsequent ureaplasmal mastitis. There was no reduction in the severity or duration of the inflammatory cell response in milk or in the clinical appearance of the resulting mastitis. Also, the excretion of ureaplasmas was not reduced.

A similar experiment with Mycoplasma dispar in two cows demonstrated that endotoxin was again ineffective in preventing the mastitis. Furthermore, there was some indication that the proliferation and excretion of this mycoplasma was enhanced in endotoxin-treated quarters.

The literature dealing with the intradermal test in whooping cough has been reviewed, and the claims as to the specific value of the test have been investigated in 1300 cases.

A method for the extraction of endotoxin from Haemophilus pertussis has been described and the intradermal response to this preparation compared with that following whole vaccine.

The findings in this investigation do not support the claim that the intradermal response to Sauer's vaccine in the strength commonly employed (10,000 million organisms per c.c.) is of value either in demonstrating immunity to whooping cough or in the early diagnosis of this disease. The bacterial content of this vaccine appears to be too high for skin-testing purposes, giving rise to inflammatory lesions of a non-specific character rather than to allergic reactions of specific value. These reactions are less apparent when the vaccine is employed in a diluted form.

The intradermal response to pertussis endotoxin, on the other hand, though not invariably consisting of a clear-cut reaction (and in this respect falling short of the ideal as a reagent) is more consistent with the development of the allergic state towards H. pertussis, reactions presumably of this nature being present in the skin of approximately 85% of children with a past history of whooping cough. Similar reactions, however, can be elicited in the skin of about 30% of individuals with no history of the disease; but in view of the fact that, unlike the more invasive virus diseases, many individuals never develop whooping cough in spite of almost certain exposure when young, it is suggested that latent immunization or recent contact with the causative organism might account for this phenomenon. Whether these reactions indicate merely sensitization or a definite immunity to pertussis must remain, for the time being, sub judice.

The onset of bacterial hypersensitiveness, as judged by the pertussis endotoxin test, appears about the 10th day of whooping cough and becomes heightened during the subsequent course of the disease. Ultimately this cutaneous allergy undergoes a regression, which, however, is not always complete. For this reason the pertussis endotoxin test would appear to be of some value in assessing the immune state of the individual, and also as a diagnostic reaction in early, atypical or late cases of whooping cough where bacteriological findings by the cough plate method have proved disappointing.

The objective of this study was to assess the effectiveness of a catheter-related bloodstream infection (CR BSI) reduction programme and healthcare workers' compliance with recommendations. A 3-year surveillance programme of CR BSIs in all hospital settings was implemented. As part of the programme, there was a direct observation of insertion and maintenance of central venous catheters (CVCs) to determine performance. A total of 38 education courses were held over the study period and feedback reports with the results of surveillance and recommendations were delivered to healthcare workers every 6 months. A total of 6722 short-term CVCs were inserted in 4982 patients for 58 763 catheter-days. Improvements of compliance with hand hygiene was verified at the insertion (87·1–100%, P < 0·001) and maintenance (51·1–72·1%, P = 0·029) of CVCs; and the use of chlorhexidine for skin disinfection was implemented at insertion (35·7–65·4%, P < 0·001) and maintenance (33·3–45·9%, P < 0·197) of CVCs. There were 266 CR BSI incidents recorded with an annual incidence density of 5·75/1000 catheter-days in the first year, 4·38 in the second year [rate ratio (RR) 0·76, 95% confidence interval (CI) 0·57–1·01] and 3·46 in the third year (RR 0·60, 95% CI 0·44–0·81). The education programme clearly improved compliance with recommendations for CVC handling, and was effective in reducing the burden of CR BSIs.

The literature of human infection with Salmonella choleraesuis in China was fully reviewed with special reference to those written in Chinese language which are inaccessible to many readers. Compared with other regions of the world the ratio of S. choleraesuis to other salmonella infection in Hong Kong is high and is parallel to that in China. Dietetic habits of the local population apparently contribute to the high incidence. The clinical manifestations of 47 cases were outlined and details of the biochemical reactions and in vitro drug sensitivities of these strains were described. Two diphasic H2S-positive strains were encountered.

The two methods for measuring the haemagglutinin content of an influenza virus suspension are the haemagglutinating (HA) and chick cell agglutinating (CCA) techniques and both measure the same biological activity. With the establishment of an international reference preparation for influenza virus haemagglutinin (type A), however, it seems logical to express the haemagglutinin content of influenza vaccines in international units. Accordingly a collaborative study was arranged in order to obtain agreement on the number of units to be assigned to a British reference preparation for influenza haemagglutinin. It was agreed that the preparation contains 190 i.u. per ampoule and 1 i.u. is contained in 0·0622 mg. of the dried material.

Aerosol vaccination of mice with purified plain tetanus toxoid does not induce an immune response unless a suitable adjuvant is added.

Aluminium phosphate is without effect by aerosol treatment. Killed cells of Klebsiella pneumoniae, although effective, are unsatisfactory owing to the long inhalation period needed.

Killed Bordetella perussis cells were found to be an excellent adjuvant. A single aerosol treatment with a toxoid-B. pertussis mixture during a moderate exposure period evoked a considerable immune response. With repeated aerosol treatment of primed mice the addition of adjuvant is not required; booster treatment with plain toxoid is at least as effective.

Extracts from B. pertussis cells exert as good an adjuvant effect as the whole-cell vaccine. The remaining cell-wall debris also appears to be an active adjuvant.

In combination with constant doses of adjuvant (108B. pertussis cells), the 50 % protective doses (ED 50) of toxoid were determined by inhalation and by s.c. injection and were found to be 0·1875 and 0·0625 LFU respectively. This would imply that, as a result of the adjuvant action, the s.c. ED 50 is reduced by approximately a factor of 20; whereas the respiratory ED 50 is decreased by at least a factor of 100.

It is suggested that the much more pronounced adjuvant activity in aerosol immunization is associated with the induction of strong cell-mediated hypersensitivity in the respiratory tract.

A field experiment was conducted from July 1958 to February 1959 in the San Francisco Bay region to test the effect on flea populations of prolonged exposure of the native meadow vole, Microtus californicus, to 5% DDT powder in insecticide-bait-boxes. Previous studies had shown that two important vectors of sylvatic plague, Malaraeus telchinum and Hystrichopsylla linsdalei, could be controlled both on their hosts and in the host nests by this method. However, the question of possible resistance was postulated since the control of H. linsdalei on its host was inferior to control of other flea species.

Bait-boxes with DDT powder were maintained in the field for 6 months. Records of flea populations on Microtus during this period showed equally good control of all flea species. Observations on vole nests at termination of the study revealed deposits of DDT and good control of all flea species in them. During the period of study, the evidence suggested that none of the flea species involved exhibited DDT resistance.

The major portion of the field routine was done by Messrs A. R. Kinney and R. L. Martin. Flea identifications were made by Mr H. E. Stark. Analyses of nests and rodents for DDT were performed by Mr C. Cueto, Technical Development Laboratories, CDC, Savannah, Georgia.

I Know that you have finished your study in tropical medicine and hygiene at this school. And so, surely, I am not wide of the mark if I suppose there is very little in the way of facts and views you have not, at least, heard of. I think it rather useless to try to add one more small fact, or one more insignificant view, to the hoard of knowledge stored in your brains, or in your notebooks.