Retention in care is a key feature of the cascade of continuum of care, playing an important role in achieving therapeutic success and being crucial for reduction of HIV transmission. The aim of this study was to evaluate the rate of retention in care in a large referral centre in the North of Italy and to identify predictors associated with failed retention. All new HIV-infected subjects were consecutive enrolled from 1 January 2008 to 31 December 2014. Demographics, immune-virological status, hepatitis co-infection and timing of initiation of combined antiretroviral therapy (cART) data were collected at baseline and at the time of last observation. Failed retention in care was defined as lack of laboratory data, clinical visits and drug dispensation for more than 6 months from the last visit. Cox regression analysis was used. Multivariate analysis of variables with P<0.05 in univariate analysis was performed. We enrolled 269 patients (mean age 46.1 years). Males were 197 (73%), Italian 219 (81%) with mean length of disease of 5.1 years. cART was prescribed for 257 patients (95%). The rate of retention in care was 78.4% and the rate of virological suppression was 75%. Predictors of being loss to follow-up were foreign origin (P = 0.048), CD4+ count <200/mmc (P = 0.001) and not being treated for HIV infection (P = 0.0004). Predictors of cART efficacy were shorter duration of HIV infection and baseline HIV-RNA <100 000 copies/ml. These findings underline the necessity to improve retention in care by identifying groups at increased risk of being loss to follow-up. Retention in care of vulnerable population is crucial to reach 90-90-90 UNAIDS endpoint.

The results of typing of 121 strains in the Mycobacterium tuberculosis complex by PFGE are presented. Every isolate from patients in Scotland over a 3-month period for M. tuberculosis and for 1 year for M. bovis were included along with several laboratory strains including those of BCG. The PFGE results suggest that the population structure of all the strains in this complex is distinctly simple with limited genetic diversity and also suggest that M. bovis is not a distinct species.

1. Altogether 117 strains of Brucella, belonging to different types and isolated from different parts of the world, have been examined by the thermoagglutination, salt agglutination, acid agglutination, and specific serum agglutination tests.

2. The results obtained by the thermo-agglutination and the serum agglutination tests are in close agreement; there is a fairly high degree of correlation between these tests and the acid agglutination test, and a rather lower correlation with the salt agglutination test.

3. Generally speaking, a strain which is highly thermo-agglutinable is frequently agglutinated by salt, is usually agglutinated strongly by acid, and reacts to a paramelitensis, but not to an abortus serum.

4. A strain which is moderately thermo-agglutinable is seldom agglutinated by salt, is frequently agglutinated by acid, and reacts either with an abortus or a paramelitensis serum, or with both sera.

5. A strain which is not thermo-agglutinable is not agglutinated by salt, seldom reacts markedly to acid agglutination, and is generally agglutinated by an abortus, but not by a paramelitensis serum.

6. There remain, however, a certain number of strains, particularly of the porcine and bovine abortus types which, though non-thermo-agglutinable, inagglutinable by salt, and reacting only with an abortus serum, yet show some degree of acid agglutination.

7. Of the twelve porcine strains examined only one strain was strongly thermo-agglutinable; of the forty-seven bovine strains only two were strongly thermo-agglutinable, a further two showing a milder degree of thermoagglutinability; of the forty-seven melitensis strains eight were strongly, and thirteen were moderately thermo-agglutinable; while of the eleven paramelitensis strains ten were strongly thermo-agglutinable.

8. These results are taken to indicate, in accordance with the suggestion made by certain previous workers, that those strains which are non-thermoagglutinable, are not agglutinated by salt, and are agglutinated by an abortus but not by a paramelitensis serum, represent the smooth form, while those strains which are strongly thermo-agglutinable, are frequently agglutinated by salt, and are agglutinated by a paramelitensis but not by an abortus serum, represent the rough form.

9. If this interpretation is correct it will be noticed that the great majority of the porcine and bovine strains examined were of the smooth type, that nearly half the melitensis strains were partially or completely rough, while all but one of the paramelitensis strains were rough.

10. Whether melitensis strains have a greater tendency than abortus strains to undergo the smooth to rough transformation it is difficult to say with certainty, but the reports in the literature and the observations in the present paper render this probable.

11. By serial passage through broth at 5-day intervals, it is possible to transform smooth strains of all three types into the rough form. This transformation appears to occur more readily and to proceed further in a given time with melitensis than with abortus strains; but since only three strains of each type were examined, the results may have been determined as much by chance selection of strains as by any greater inherent tendency of the strains of the melitensis type to undergo variation.

12. It is clear that none of the tests employed suffices to differentiate individual strains of abortus and melitensis. The thermo-agglutination test and the agglutination test with specific smooth and rough sera do, however, enable a differentiation to be made between smooth and rough strains of all types.

13. In the present paper no attempt has been made to distinguish abortus and melitensis strains by specific agglutination and absorption tests. The general failure of workers hitherto to obtain any clear-cut serological distinction between these types may possibly be due to the fact that many of the strains with which they worked were either partially or completely rough. Since the rough antigen seems to be more or less alike in strains of all types, it is clear that its presence would tend to obscure any difference that might exist between the smooth antigens of the different types. If such a difference does exist it is probable that it will be elicited only by a comparison of absolutely smooth strains.

In this study 197 strains of Escherichia coli isolated from cowpats and the faeces of healthy humans were examined for the presence of enterotoxins. Six strains representing five different serotypes were found to be enterotoxigenic. Four of these strains produced the heat labile enterotoxin and two, the Vero cell cytotoxin.

During a 7½ year period pneumococci were isolated from body fluids of 124 patients at the Radcliffe Infirmary, Oxford – 72 with pneumonia, 26 with meningitis and 26 with other serious infections. Eighty-one (65%) of the patients were over 50, and 33 (27%) were over 70 years old. Of the 124 pneumococcal strains 104 (84%), including 23 (79%) of those from patients who died, belonged to types included in the vaccines successfully used in South Africa and in Papua New Guinea. The relative frequencies of types in the Oxford series and in a larger British series agreed closely with those found in a recent survey of 3644 bacteraemic pneumococcal infections in 10 American cities. Any polyvalent pneumococcal vaccine licensed for use in the United States is thus likely to be relevant to the situation in Britain.

Although vaccines have become available, emergence and rapid transmission of new variants have added new paradigm in the coronavirus disease-2019 (COVID-19) pandemic. Weather, population and host immunity have been detected as the regulatory elements of COVID-19. This study aims to investigate the effects of weather, population and host factors on the outcome of COVID-19 and mutation frequency in Japan. Data were collected during January 2020 to February 2021. About 92% isolates were form GR clades. Variants 501Y.V1 (53%) and 452R.V1 (24%) were most prevalent in Japan. The strongest correlation was detected between fatalities and population density (rs = 0.81) followed by total population (rs = 0.72). Relative humidity had the highest correlation (rs = −0.71) with the case fatality rate. Cluster mutations namely N501Y (45%), E484K (30%), N439K (16%), K417N (6%) and T478I (3%) at spike protein have increased during January to February 2021. Above 90% fatality was detected in patients aged >60 years. The ratio of male to female patients of COVID-19 was 1.35:1. This study will help to understand the seasonality of COVID-19 and impact of weather on the outcome which will add knowledge to reduce the health burden of COVID-19 by the international organisations and policy makers.

Schistosoma japonicum infection associated with a rectal carcinoid in an asymptomatic 44-year-old female from the Philippines is described. A systematic review of the literature could not identify similar reports, suggesting a rare coincidence. However, epidemiological data on the frequency of both conditions as well as published results of a colorectal screening programme from China indicate that underreporting of this concurrence is likely. Moreover, several studies suggest a causal link between schistosomiasis caused by S. japonicum and more common gastrointestinal malignancies such as colorectal carcinoma. Hence the presented case and the apparent neglect of this observation in the current literature allow speculation on a role of S. japonicum in the pathogenesis of rare gastrointestinal neoplasms such as carcinoid tumours as well. Future reports on similar observations could help to determine the need for systematic investigations and are strongly encouraged.

We investigated two sequential outbreaks of severe diarrhoea in two neighbouring villages of Orissa, in 2005. We conducted descriptive and matched case-control studies. The attack rates were 5·6% (n=62) and 5·2% (n=51), respectively, in the first and second villages. One death was reported in the second village (case fatality 2%). We identified that consumption of milk products prepared in the household of the index case [matched odds ratio (mOR) 5·7, 95% confidence interval (CI) 1·7–30] in the first village, and drinking well water in the second village were associated with the illness (mOR 4·7, 95% CI 1·6–19). We isolated Vibrio cholerae El Tor O1 Ogawa from stool samples from both the villages. Mishandling of milk products led to a cholera outbreak in the first village, which led to sewerage contamination of a well and another outbreak in the second village. Environmental contamination should be expected and prevented during cholera outbreaks.

The bactericidal effect of ultra-violet radiation on dried films of β-haemolytic streptococci has been shown to be dependent both on the relative humidity and on the nature of the suspending medium from which the films are prepared. In particular, while the bactericidal action is most often more repaid under dry conditions, films prepared from suspensions in dust extract culture show a similar behaviour to that of naturally occurring dust flora and are most resistant to the effects of radiation under dry conditons.

Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis and Staphylococcus aureus colonization of the adenoids and nasopharynx in 103 preschool children who underwent adenoidectomy for recurrent upper respiratory tract infections was examined. Bacterial interactions and risk factors for bacterial colonization of the nasopharynx and adenoids, separately, were analysed statistically. The prevalence of simultaneous isolation from both anatomical sites was 45·6% for S. pneumoniae, 29·1% for H. influenzae, 15·5% for M. catarrhalis and 18·4% for S. aureus. Three pathogens were significantly more frequent together from adenoid samples; nasopharyngeal swabs more often yielded a single organism, but without statistical significance. M. catarrhalis and S. aureus significantly more frequently co-existed with S. pneumoniae and H. influenzae than with each other and a positive association of S. pneumoniae and H. influenzae in adenoid samples was evident. Several differences between risk factors for nasopharyngeal and adenoid colonization by the individual pathogens were observed. We conclude that the adenoids and nasopharynx appear to differ substantially in colonization by pathogenic microbes but occurrence of H. influenzae and S. pneumoniae in the nasopharynx could be predictive of upper respiratory tract infections.

The bacterium Neisseria meningitidis causes life-threatening disease worldwide, typically with a clinical presentation of sepsis or meningitis, but can be carried asymptomatically as part of the normal human oropharyngeal microbiota. The aim of this study was to examine N. meningitidis carriage with regard to prevalence, risk factors for carriage, distribution of meningococcal lineages and persistence of meningococcal carriage. Throat samples and data from a self-reported questionnaire were obtained from 2744 university students (median age: 23 years) at a university in Sweden on four occasions during a 12-month period. Meningococcal isolates were characterised using whole-genome sequencing. The carriage rate among the students was 9.1% (319/3488; 95% CI 8.2–10.1). Factors associated with higher carriage rate were age ≤22 years, previous tonsillectomy, cigarette smoking, drinking alcohol and attending parties, pubs and clubs. Female gender and sharing a household with children aged 0–9 years were associated with lower carriage. The most frequent genogroups were capsule null locus (cnl), group B and group Y and the most commonly identified clonal complexes (cc) were cc198 and cc23. Persistent carriage with the same meningococcal strain for 12 months was observed in two students. Follow-up times exceeding 12 months are recommended for future studies investigating long-term carriage of N. meningitidis.

The results of treatment of influenza virus strains with chemical reagents acting on the higher-order structure of protein molecules shows that both the haemagglutinating and enzymic activities are susceptible to these agents but there are considerable differences between the different strains and the neuraminidase activity is more sensitive than the haemagglutinating activity.

The neuraminidase activity of A and A1 strains is destroyed by urea, guanidine, urea+dithiothreitol and mercuric chloride. The haemagglutinin of the PR 8 and SWINE strains is resistant to urea and mercuric chloride but destroyed by guanidine and by urea+dithiothreitol. The haemagglutinin of the DSP strain of virus A and the A1 strains is resistant to urea, guanidine and mercuric chloride but is destroyed by urea+dithiothreitol.

The neuraminidase activity of the A2 strains is more resistant than that of the A and A1 strains. It is resistant to mercuric chloride and partially resistant to urea but is destroyed by guanidine and by urea+dithiothreitol. The A2 haemagglutinin is resistant to urea, urea+dithiothreitol, and mercuric chloride but is destroyed by guanidine.

The LEE virus neuraminidase is resistant to urea and partially resistant to guanidine but is destroyed by urea+dithiothreitol and mercuric chloride. The LEE haemagglutinin is resistant to urea, guanidine and mercuric chloride but is destroyed by urea+dithiothreitol.

It is suggested that the surface projections of the virus particle are protein polymers each made up of three or four monomers which are the components of the V antigen complex. Antigenic activity is a function of the primary or secondary structure of the monomers, haemagglutinin activity is a function of the tertiary structure of the monomers, while neuraminidase activity is a function of the quaternary structure of the polymer.

From studies of the chemical reactions of their haemagglutinins and neuraminidases strains of influenza virus A can be classified into groups. These groups are very similar to but not precisely identical with groupings made by serological methods.

Experiments performed on spore formation in B. anthracis, in a wide range of closed atmospheres of chemically controlled humidity, showed that the sporing time of B. anthracis is prolonged considerably as the humidity decreases, both at 26 and 37° C. The effect is less noticeable at the lower temperature.

Experiments performed on spore germination in the same organism showed that a temperature range of 20–44° C. permitted germination of the five strains tested. Above a temperature of 39° C. and below 30° C. germination time lengthened considerably.

Experiments performed on the influence of humidity on spore germination, both at 26 and 37° C. showed that no germination could take place at a relative humidity of 80% or below. Germination time was considerably prolonged when the humidity value fell below 100%.

This work formed part of a thesis for the degree of M.D. in Bristol University. I wish to thank Dr G. S. Wilson for his advice in preparing this paper.

Systematic, national surveillance of outbreaks of intestinal infectious disease has been undertaken by Public Health England (PHE) since 1992. Between 1992 and 2002, there were 19 outbreaks linked to raw drinking milk (RDM) or products made using raw milk, involving 229 people; 36 of these were hospitalised. There followed an eleven-year period (2003–2013) where no outbreaks linked to RDM were reported. However, since 2014 seven outbreaks of Escherichia coli O157:H7 (n = 3) or Campylobacter jejuni (n = 4) caused by contaminated RDM were investigated and reported. Between 2014 and 2017, there were 114 cases, five reported hospitalisations and one death. The data presented within this review indicated that the risk of RDM has increased since 2014. Despite the labelling requirements and recommendations that children should not consume RDM, almost a third of outbreak cases were children. In addition, there has been an increase in consumer popularity and in registered RDM producers in the UK. The Food Standards Agency (FSA) continue to provide advice on RDM to consumers and have recently made additional recommendations to enhance existing controls around registration and hygiene of RDM producers.

Hendra virus (HeV) was first described in 1994 in an outbreak of acute and highly lethal disease in horses and humans in Australia. Equine cases continue to be diagnosed periodically, yet the predisposing factors for infection remain unclear. We undertook an analysis of equine submissions tested for HeV by the Queensland government veterinary reference laboratory over a 20-year period to identify and investigate any patterns. We found a marked increase in testing from July 2008, primarily reflecting a broadening of the HeV clinical case definition. Peaks in submissions for testing, and visitations to the Government HeV website, were associated with reported equine incidents. Significantly differing between-year HeV detection rates in north and south Queensland suggest a fundamental difference in risk exposure between the two regions. The statistical association between HeV detection and stockhorse type may suggest that husbandry is a more important risk determinant than breed per se. The detection of HeV in horses with neither neurological nor respiratory signs poses a risk management challenge for attending veterinarians and laboratory staff, reinforcing animal health authority recommendations that appropriate risk management strategies be employed for all sick horses, and by anyone handling sick horses or associated biological samples.

We took the opportunity provided by a large outbreak of cryptosporidiosis in the North West of England to investigate the potential impact of recall bias on strength of association and on estimates of outbreak size. We conducted a community-based survey of 4 towns within the outbreak area and 4 control towns. A postal questionnaire was sent to 120 homes, chosen at random from the local telephone directory, in each of the 8 towns. Although not statistically significant, the prevalence of self-reported diarrhoeal disease was marginally higher in the control towns than in the outbreak towns. There was a very strong association between self-reported diarrhoea and drinking water consumption in both control and outbreak areas. The impact of recall bias in outbreak investigations is much greater than previously thought. Identification of the cause of outbreaks should not be based solely on case-control studies conducted after the press has reported the outbreak. Such evidence is likely to be unreliable and give falsely significant associations between water consumption and disease.

The efficacy of seven rodenticides for use against Sigmodon hispidus was investigated in the laboratory. The poisons (warfarin, coumatetralyl, difenacoum, brodifacoum, bromadiolone, calciferol and zinc phosphide) were all toxic at the concentrations normally used against Rattus rattus and R. norvegicus and all were palatable.

Trials are now needed to confirm the efficacy of these poisons in the field, but it seems likely that, if used in suitable bait formulations, they would all be useful for the practical control of S. hispidus.

Giardiasis, caused by the intestinal protozoan parasite Giardia intestinalis (synonyms: G. lamblia, G. duodenalis), is one of the most frequent parasites to infect the Scottish population. Transmission of the infective cysts in faecal matter is commonly via food and/or water. Giardia is subdivided into assemblages, where clinical and epidemiological differences have been described between assemblages A and B. This snapshot descriptive epidemiological study examines 30 positive cases of Giardia of which 72% (n = 21) were shown to be assemblage A, 14% (n = 4) assemblage B and 10% (n = 3) mixed assemblages (A and B). There was a 2:3 female:male ratio of affected individuals with foreign travel recorded in 22 of these cases. The commonest symptom was diarrhoea which was reported in 80% of cases followed by tiredness. Five cases required hospitalization emphasizing the importance of gaining a greater understanding of how Giardia assemblages influence clinical outcomes to assist in formulating guidelines to manage potential Giardia outbreaks.

B. dysenteriae (Sonne Type III) may be separated from the dispar group by the fact that it is indol negative and zylose negative. It is usually inagglutinable when freshly isolated but will remove all agglutinins from a Sonne serum. B. dysenteriae (Sonne Type III) is a serological entity and can readily be distinguished from B. dysenteriae Flexner and from the dispar group. Eleven strains of B. dysenteriae (Sonne Type III) have been isolated and examined, along with standard cultures of this group of organisms.

Terminal complement component deficiency predisposes to meningococcal infection and is inherited in an autosomal co-dominant manner. An Irish family is described, in which 2 of 3 brothers had recurrent meningococcal infection. A novel screening assay was used to investigate for terminal complement deficiency and the 2 affected brothers were found to be completely deficient in the seventh component of complement (C7). Enzyme-linked immunosorbent assay for C7 revealed lower than normal levels in the remaining brother and parents. C7 M/N protein polymorphism allotyping, used to investigate the segregation of the C7 deficiency genes, showed that the apparently complement sufficient brother was heterozygous C7 deficient and a carrier of one of the deficiency genes. Complement screening should be carried out in any individual suffering recurrent meningococcal infection or infection with an uncommon meningococcal serogroup. Identification of complement deficient patients allows the implementation of strategies to prevent recurrent infection.