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Biomedical subjects

A Judd

Publications and source records attributed to A Judd.

At least 19 recordsLinked to original sources
PubMed2007

Modelling the impact on Hepatitis C transmission of reducing syringe sharing: London case study.

BACKGROUND: Hepatitis C virus (HCV) prevalence and incidence among injecting drug users (IDUs) has increased in London and rest of UK. To inform public health action, mathematical modelling is used to explore the possible impact of strategies to decrease syringe sharing. METHODS: A mathematical model was developed to simulate HCV transmission amongst IDUs in London. Because of parameter uncertainty, numerical search algorithms were used to obtain different model fits to HCV seroprevalence data from London for 2002-03. These simulations were used to explore the likely impact of HCV prevention activities that reduce syringe sharing amongst all IDUs, IDUs that have injected for greater than one year, or IDUs with lower or higher frequencies of syringe sharing. RESULTS: Key differences between model fits centred on how they simulated the high HCV incidence amongst new injectors, either through assuming increased HCV infectivity during acute infection, a large sub-group of high frequency syringe sharers, or increased sharing among new IDUs. Despite parameter uncertainty, the model projections suggest that modest reductions in syringe sharing frequency (<25%) will reduce the HCV seroprevalence in newly initiated IDUs (injecting less than four years) but much larger and sustained reductions (>50%) are required to reduce the HCV seroprevalence in long-term IDUs (injecting more than 8 years). Critically the model also suggested that large reductions in HCV seroprevalence will be achieved only if interventions target all IDUs and reach IDUs within 12 months of injecting. DISCUSSION: Public health interventions must reduce syringe sharing amongst all IDUs, including newly initiated IDUs, and be sustained for many years to reduce HCV infection. More accurate data on key behavioural (sharing frequency) and biological (percentage of infected IDUs that clear infection) parameters is required to improve model projections.

Female↗
PubMed2005

Prevalence of, and risk factors for, hepatitis C virus infection among recent initiates to injecting in London and Glasgow: cross sectional analysis.

Our aim was to compare the prevalence of antibody to hepatitis C virus (anti-HCV) among recently initiated injecting drug users (IDUs) in London and Glasgow, and to identify risk factors which could explain differences in prevalence between the cities. Complementary studies of community recruited IDUs who had initiated injection drug use since 1996 were conducted during 2001-2002. Data on HCV risk behaviours were gathered using structured questionnaires with identical core questions and respondents were asked to provide an oral fluid specimen which was tested anonymously for anti-HCV but was linked to the questionnaire. Sensitivities of the anti-HCV assays for oral fluid were 92-96%. Prevalence of anti-HCV was 35% (122/354) in London and 57% (207/366) in Glasgow (P < 0.001). Multifactorially, factors significantly associated with raised odds of anti-HCV positivity were increasing length of injecting career, daily injection, polydrug use, having had a needlestick injury, and having served a prison sentence. In addition lower odds of anti-HCV positivity were associated with non-injection use of crack cocaine and recruitment from drug agencies. After adjustment for these factors, the increased odds of anti-HCV associated with being a Glasgow IDU were diminished but remained significant. HCV continues to be transmitted among the IDU population of both cities at high rates despite the availability of syringe exchange and methadone maintenance. Effectiveness of harm reduction interventions may be compromised by inadequate coverage and failure to reduce sufficiently the frequency of sharing different types of injecting equipment, as well as the high background prevalence of HCV, and its high infectivity. Comprehensive action is urgently required to reduce the incidence of HCV among injectors.

Adult↗
PubMed2001

A marker-dense physical map of the Bradyrhizobium japonicum genome.

Bacterial artificial chromosome (BAC) clones are effective mapping and sequencing reagents for use with a wide variety of small and large genomes. This report describes the development of a physical framework for the genome of Bradyrhizobium japonicum, the nitrogen-fixing symbiont of soybean. A BAC library for B. japonicum was constructed that provides a 77-fold genome coverage based on an estimated genome size of 8.7 Mb. The library contains 4608 clones with an average insert size of 146 kb. To generate a physical map, the entire library was fingerprinted with HindIII, and the fingerprinted clones were assembled into contigs using the software (; Sanger Centre, UK). The analysis placed 3410 clones in six large contigs. The ends of 1152 BAC inserts were sequenced to generate a sequence-tagged connector (STC) framework. To join and orient the contigs, high-density BAC colony filters were probed with 41 known gene probes and 17 end sequences from contig boundaries. STC sequences were searched against the public databases using and algorithms. Query results allowed the identification of 113 high probability matches with putative functional identities that were placed on the physical map. Combined with the hybridization data, a high-resolution physical map with 194 positioned markers represented in two large contigs was developed, providing a marker every 45 kb. Of these markers, 177 are known or putative B. japonicum genes. Additionally, 1338 significant results (E < 10(-4)) were manually sorted by function to produce a functionally categorized database of relevant B. japonicum STC sequences that can also be traced to specific locations in the physical map.

Bradyrhizobium↗
PubMed2001

Prevalence of hepatitis C among injection drug users in England and Wales: is harm reduction working?

OBJECTIVES: This study sought to establish the prevalence of hepatitis C antibodies (anti-HCV) and hepatitis B antibodies (anti-HBc) among injection drug users in England and Wales. METHODS: A voluntary cross-sectional survey collected oral fluid samples and behavioral information; 2203 injectors were recruited through drug agencies, and 758 were recruited in the community. RESULTS: Prevalence was 30% for anti-HCV, 21% for anti-HBc, and 0.9% for HIV antibodies. Anti-HCV prevalence rates were significantly greater among those with longer injecting careers, those in older age groups, those residing in London, those recruited in drug agencies, those positive for anti-HBc, and those with a previous voluntary HIV test. CONCLUSIONS: Anti-HCV prevalence rates among injectors in England and Wales, where comprehensive harm reduction programs exist, are lower than rates in other industrialized countries.

Adult↗
PubMed2000

Measuring injecting risk behaviour in the second decade of harm reduction: a survey of injecting drug users in England.

AIMS: To measure risk behaviour among injecting drug users (IDUs) using the Injecting Risk Questionnaire (IRQ). METHODS: Data were analysed from the first multi-site survey of injecting risk behaviour among IDUs not in contact with drug services in England. A total of 1214 IDUs were recruited from community settings in seven sites. FINDINGS: Fifty-two per cent reported sharing injecting equipment in the previous 4 weeks in response to a single question on sharing. This rose to 78% when asked more detailed and multiple questions on injecting risk practices. Levels of injecting risk behaviour did not differ substantially by gender, age, length of injecting career, main drug of injection, previous treatment contact or geographical location. However, sharing partners were restricted to a median of two others. CONCLUSION: These data raise questions concerning the extent to which levels of injecting risk behaviour have increased over recent years, or the extent to which previous monitoring systems underestimated levels of risk. None the less, the data confirm that the promotion of safer injecting continues to be an important public health issue with regard to reducing blood-borne infections.

Adolescent↗
PubMed2000

Prevalence of sexual dysfunction in new heterosexual attenders at a central London genitourinary medicine clinic in 1998.

OBJECTIVE: To determine the prevalence of sexual dysfunction and dissatisfaction (SD) among new heterosexual attendees at a central London genitourinary medicine (GUM) clinic. METHODS: Consecutive new attendees seen by a single clinician were asked a probe question about SD in the previous year. A clinical interview followed a positive response to the probe question. Demographic information was obtained using standard clinic forms. RESULTS: 37% of 103 men and 20% of 100 women participants gave positive responses, and 24% of the men and 12% of the women wanted treatment for their problems. CONCLUSIONS: Our results indicate a relatively high rate of SD in new GUM clinic attendees that is not currently being detected or managed. SD may lead to psychological problems, which can be reversed with appropriate treatment. The financial implications of such treatment are discussed.

Adult↗
PubMed2000

Prevalence of Chlamydia trachomatis in young men in north west London.

BACKGROUND: Chlamydia trachomatis is the most common, treatable, bacterial sexually transmitted infection in England and Wales. Among men, chlamydial infection is an important cause of non-gonococcal urethritis, epididymitis, and proctitis. The case for wider screening among women has been accepted by an expert advisory group. In the absence of estimates of the prevalence of infection in men, its potential impact at the population level is difficult to assess. OBJECTIVE: To estimate the prevalence of Chlamydia trachomatis in young men in clinic and community based samples in north west London. METHOD: Cross sectional survey in healthcare centres and general practices in north west London. 1002 males aged 18-35 years, living in north west London, were recruited by staff in occupational health departments, general practices, student health services, and a "well man" clinic and by postal recruitment in four GP practices. The men were tested for C trachomatis using the ligase chain reaction assay on urine samples. The main outcome measure was prevalence of C trachomatis infection in men aged 18-35 years. RESULTS: The overall response rate was 51%. Prevalence of confirmed infection was 1.9% (95% CI: 1.14% to 2.96%) in all men. Best estimated minimum prevalence of infection was 1% (95% CI: 0.58% to 1.50%). Estimated prevalence was highest among men aged over 30 years. CONCLUSIONS: The estimated prevalence among men is commensurate with that described for female populations in London. The results suggest that recruitment of men to screening programmes would be difficult. However, a higher proportion of chlamydial infection may be detected in men than in women by existing approaches to control through genitourinary medicine clinic based case finding and contact tracing. Screening of young women and the contact tracing of the male partners of positive females may be an efficient approach to improving chlamydia control.

Adolescent↗
PubMed1999

HIV prevalence and risk behaviour among female injecting drug users in London, 1990 to 1996.

OBJECTIVE: To describe trends in HIV prevalence among female injecting drug users (IDU) in London between 1990 and 1996. DESIGN: HIV prevalence and risk behaviour were measured yearly between 1990 and 1993, and in 1996, in point prevalence HIV surveys of IDU recruited from both drug-treatment and community-based settings within Greater London. Sample sizes were 173 in 1990, 111 in 1991, 128 in 1992, 146 in 1993 and 200 in 1996. METHODS: Each survey used structured questionnaires and common sampling and interview strategies. Oral fluid specimens were collected for testing for antibodies to HIV (anti-HIV). Multiple logistic regression was used to assess the trend in HIV prevalence. RESULTS: The percentage of female IDU testing positive for antibodies to HIV showed a marked decline over the study period, from 15.0% in 1990 to 1.0% in 1996 (P < 0.001). This trend was independent of all other variables examined. Each year, higher HIV prevalences were found among IDU recruited from community settings compared with treatment agencies. CONCLUSIONS: These results concur with those of IDU recruited from treatment sites, although the yearly estimates in this study are higher. London benefits from low prevalence of HIV infection among IDU, coupled with behaviour change facilitated by early intervention. Continued surveillance of injectors recruited from both community and treatment settings is necessary in order properly to assess HIV prevalence among IDU.

Data Collection↗
PubMed1999

Incidence of gonorrhoea diagnosed in GUM clinics in South Thames (west) region.

OBJECTIVES: To describe the incidence of gonorrhoea diagnosed in genitourinary medicine (GUM) clinics in South Thames (West) between 1995 and 1996, and how it changed among population subgroups. SETTINGS AND SUBJECTS: Cases of uncomplicated and complicated gonorrhoea diagnosed at 13 GUM clinics in the former South Thames West (STW) Regional Health Authority that reported disaggregate data to the South Thames GUM Clinic Collaborative STD Surveillance Scheme. METHODS: Annual incidence rates (per 100,000) of gonorrhoea diagnoses by sex, age group, ethnic group, area of residence, and year were calculated. Poisson regression models were used to calculate risk ratios (RR) to describe the key differences in the variation of gonorrhoea cases by these variables. Relative differences in the incidence of diagnosed gonorrhoea between 1995 and 1996 were investigated by including an interaction between year and the other variables (age group, sex, ethnic group, region) and testing whether any were significant using a likelihood ratio test. RESULTS: Area of residence, sex, age group, and ethnic group were key predictors of the rates of diagnosed gonorrhoea. The risk ratio for gonorrhoea (after adjustment for the other variables) was: 13 times higher among blacks than the white population; twice as high in inner London compared with outer London; and three times lower in the "shire" region compared with outer London. The rate of diagnosed gonorrhoea was significantly higher in the black population in the shire region than the inner London white population. The rate of gonorrhoea diagnosed by GUM clinics from 1995 to 1996 almost doubled in the white population aged 15-44 years, from 16 cases per 100,000 to 30 cases per 100,000 (adjusted RR 2.0, 95% CI 1.6 to 2.4), whereas increased rates in the black and Asian/other ethnic groups were not statistically significant (adjusted RR 1.1, 95% CI 0.9 to 1.4; and 1.4, 95% CI 0.7 to 2.7 respectively). CONCLUSION: The observed increase in gonorrhoea between 1995 and 1996 occurred mostly among heterosexual white men and women. Overall, the rates of gonorrhoea among young people, especially in the black population and in inner London represent a significant public health problem that may merit further targeted interventions, the effectiveness of which could be monitored through further development of routine surveillance data.

Adolescent↗
PubMed1998

Women injecting drug users in London: the extent and nature of their contact with drug and health services.

Improved access to drug treatment and other health services remains central to HIV prevention and other harm reduction strategies among injecting drug users (IDUs) in the UK. Efforts have therefore been focused upon making such services more accessible and 'user friendly'. Women who use drugs are considered a 'hard to reach' population. This is largely based on data from a variety of official sources which have suggested that women are under-represented as clients of drug services. While current literature provides numerous explanations for this, there have been few empirical studies exploring the nature and extent of women's contact with such services. This paper presents findings from an European Community funded survey of women IDUs in London. Data from this survey suggest that women IDUs have surprisingly high levels of contact with a range of specialist and generic health services in relation to their drug use.

Journal Article↗
PubMed1996

T-cell proliferative response to human papillomavirus type 16 peptides: relationship to cervical intraepithelial neoplasia.

The incidence of human papillomavirus (HPV)-related cervical intraepithelial neoplasia (CIN) and cervical cancer is increased with immunodeficiency, but the role of immune response, including cell-mediated immunity, in disease prevention is not well understood. In this study, T-cell proliferative responses to six synthetic peptides with predicted immunogenic determinants from the HPV-16 E4, E6, E7, and L1 open reading frames were analyzed in 22 sexually active women with new-onset CIN and 65 sexually active women without cervical disease, characterized by cytology, colposcopy, and HPV testing. T-cell proliferative responses were demonstrated to all six HPV-16 peptides. Although not statistically significant, rates of reactivity to E6 (24-45) were higher among sexually active women without disease (26%) than among women with current CIN (7%), as was the overall number of peptides stimulating a response. Women with CIN may not respond to selected HPV antigens as well as women without disease do.

Adult↗