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Biomedical subjects

O N Gill

Publications and source records attributed to O N Gill.

At least 37 records · Page 2Linked to original sources
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↗
PubMed2001

International surveillance networks and principles of collaboration.

In the face of the multiplication and the development of international surveillance networks for communicable diseases, many questions on the transmission of personal data and information arise. The confidential nature of shared data and their disclosure internationally within and outside the network are therefore potential sources for conflicts. To resolve these problems, Enter-net developed its 'Collaboration Principles' intended to apply to all the participants of the network and to all others potentially involved. These principles propose solutions to questions related to the access to databases created within the framework of the network, to the quality and confidentiality of circulating data, to the individual responsibility in the identification of an incriminated product in case of an outbreak, and even to the transmission of information outside the network. These principles, which are to be regularly reviewed, are primarily aimed at optimising early detection and management of foodborne outbreaks, and at taking the necessary measures for public health. Considering the nature of the problems, however, some of these principles are also of relevance to other surveillance networks.

Communicable Disease Control↗
PubMed2001

Test of HIV incidence shows continuing HIV transmission in homosexual/bisexual men in England and Wales.

It has been suggested that HIV incidence will decrease with the increased use of antiretroviral Therapy (ART) in HIV infected homosexual/bisexual men. HIV incidence was measured using a sensitive/less sensitive assay technique, at a time when combination ART was widespread. The Serological Testing Algorithm for Recent HIV Seroconversion (STARHS)13 technique was applied to syphilis test specimens collected from homosexual/bisexual men attending 15 sexually transmitted infections (STI) clinics which participated in an unlinked anonymous serosurvey of HIV infection during 1998. The HIV incidence rate was adjusted to compensate for patients who had a repeat syphilis test within the same year. Leftover syphilis test sera from 6202 men had been unlinked and anonymised, of which 415 were HIV positive. Sera from 412 (99.3%) patients were available. The STARHS assay showed 62 to have been recently infected with HIV (approximately in the last four months), giving an incidence of 3.33% per annum (95% CI: 2.06%-5.27%). The highest incidence was seen in those aged 35-44 years. About 46% of all HIV-infected homosexual/bisexual men were probably receiving combination ART at this time. If 10% of those on treatment were misclassified as recent infections the incidence would have been 2.58% per annum (95% CI: 1.53%-4.24%). In homosexual/bisexual men having syphilis tests at STI clinics in the UK during 1998 the incidence of HIV infection was between two and three per hundred per year. Treatment with combination ART of almost a half of homosexual/bisexual men who are HIV infected in the population is compatible with appreciable continuing HIV transmission among those at high behavioural risk. Public health surveillance systems for those at high risk for HIV infection should, as soon as possible, incorporate the STARHS methodology for monitoring recent HIV incidence.

Adult↗
PubMed2001

Failure to vaccinate current injecting drug users against hepatitis B in England and Wales.

In most industrialised countries the elimination of hepatitis B infection is highly reliant on effective vaccine delivery to injecting drug users. This paper highlights the very poor vaccine coverage achieved in England and Wales in the ten years since this problem was officially recognised and targeted. This is despite the existence of a comprehensive and well-utilised network of specialist services for injecting drug users.

Communicable Disease Control↗
PubMed2000

What a test for recent infection might reveal about HIV incidence in England and Wales.

BACKGROUND: A laboratory method has been developed that detects recent HIV infection and allows incidence to be estimated by testing single stored antibody-positive specimens. A theoretical exploration of the method's surveillance utility was carried out. METHODS: Using various data sources, HIV incidence rates were postulated. The confidence intervals (CI) for these postulated incidences were calculated using the expected number of recent infections for each postulated incidence, the actual number tested for HIV, and the known number of HIV-1 positives. A test for trend was used to determine when an important change in incidence could be recognized. RESULTS: If the incidence was 5% per annum (p.a.) in homosexual/bisexual men attending sexually transmitted diseases (STD) clinics in London, 64 recent infections would be expected in the 392 HIV-seropositive specimens and, if observed, would result in a 95% CI of 3.1-7.9% p.a. for the incidence rate. An incidence of 1% p.a. in pregnant women would be most unlikely as this would require detection of 193 recent infections, 26 more than the total 167 HIV-seropositive specimens found in 1997. In African women attending STD clinics in London, 30% of prevalent infections would be classified as recent if the incidence was 5% p.a. Further, if the incidence in homosexual/bisexual men were to fall by 50% over 3 years, a decrease of this magnitude would be recognized as significant within 2 years. CONCLUSIONS: The detuned assay will increase the information from HIV serosurveys even where prevalence and incidence are relatively low. Existing surveillance systems should be redesigned to take full advantage of the method.

Confidentiality↗
PubMed2000

The public health applications of unlinked anonymous seroprevalence monitoring for HIV in the United Kingdom.

BACKGROUND: In order to monitor the epidemiology of human immunodeficiency virus (HIV), integrated national programmes of unlinked anonymous (blinded) HIV sero-surveys have taken place in the UK since 1990. METHODS: The programmes comprise multi-centre surveys primarily using specimens gathered routinely for screening groups of patients. All specimens are irreversibly unlinked from patient identifiers before being tested. RESULTS: The surveys have met their prime aim of providing at low cost minimally biased estimates of current HIV prevalence and trends in sentinel populations. The surveys have remained acceptable to professionals and the public, being successfully implemented without breech of their founding principles. The findings have had major public health applications, have influenced HIV policy and funding, been used for monitoring the spread of HIV, for targeting and evaluating health promotion and improving projections of severe HIV disease. The surveys have detected substantial prevalence rises and under-diagnosis of HIV which would otherwise have been unrecognised. The programmes' value is being increased by sub-typing HIV-1 isolates, capturing additional demographic information to detect spread among minority groups. The same specimens are used for monitoring other infections (initially hepatitis A, B and C). CONCLUSIONS: Monitoring HIV and other infections through unlinked anonymous HIV surveillance has become an integral essential part of national HIV and AIDS surveillance. Although it has unique applications the value of unlinked anonymous surveillance is maximized when used in conjunction with behavioural data, information from HIV and AIDS reporting, and behavioural data and surveillance for other sexually transmitted infections.

Confidentiality↗
PubMed2000

Prevalence of HIV, hepatitis B, and hepatitis C antibodies in prisoners in England and Wales: a national survey.

Prisoners in eight of the 135 prisons in England and Wales were surveyed in 1997 and 1998 to study the prevalence of and risk factors for transmission of bloodborne viruses in prison. Subjects voluntarily completed a risk factor questionnaire and provided oral fluid specimens for unlinked anonymous testing for the presence of antibodies to HIV, hepatitis C virus (HCV), and the core antigen of hepatitis B virus (HBc). Almost 8% (4778) of the total of 60,561 prisoners were eligible and four fifths (3942) of those eligible took part. Among all those tested (3930) 0.4% (14) were positive for anti-HIV, 8% (308) for anti-HBc, and 7% (293) for anti-HCV (the anti-HBc and anti-HCV prevalences were not adjusted for assay sensitivities of 82% and 80%, respectively). Twenty-four per cent (777/3176) of adult prisoners reported ever having injected drugs, 30% of whom (224/747) reported having injected in prison. Three quarters of those who injected in prison (167/224) shared needles or syringes. Among adult injecting drug users, 0.5% (4/775) had anti-HIV, 31% (240/775) anti-HCV, and 20% (158/775) anti-HBc. The presence of anti-HCV and anti-HBc was associated with injecting inside prison and number of previous times in prison. The results suggest that hepatitis viruses are probably being transmitted in prisons through sharing non-sterile injecting equipment and that a risk of HIV transmission exists. Harm minimisation measures for the 6% of prisoners who continue to inject while in prison should be strengthened.

Adult↗
PubMed1999

New therapy explains the fall in AIDS incidence with a substantial rise in number of persons on treatment expected.

BACKGROUND: A marked decline in the number of reported AIDS cases has been observed in the United Kingdom, as in many industrialized countries, in 1996 and 1997. In England and Wales, a large reduction in AIDS cases has been recorded among homosexual and bisexual men. OBJECTIVES: To investigate, using data from the homosexuals and bisexuals in England and Wales as an example, possible explanations for the above decline such as the effects of new anti-retroviral therapies, or a decrease in the incidence of HIV in recent years. METHODS: A multistage model of HIV infection, HIV diagnosis, treatment and of AIDS diagnosis has been used to represent the pattern of HIV and AIDS incidence in homosexual and bisexual men in England and Wales up to the end of 1995. Scenarios for the post-1995 period were examined under different assumptions about changes in HIV incidence in recent years and treatment uptake and efficacy. RESULTS: The fall in the incidence of AIDS is unlikely to be the result of a reduction in HIV transmission during the 1990s. The most plausible explanation for this fall is the effect of new, more effective, anti-retroviral therapies. As a consequence, the number of individuals on treatment is likely to increase by 50 to 100% compared with the pre-1996 levels by the year 2001. Also, if the effect of the new therapies has a limited duration, or the use of such therapies is not well tolerated, the incidence of AIDS will rise again in the near future. CONCLUSIONS: These findings indicate that a substantial workload increase is under way for the healthcare system, and reiterate the need for measures to reduce HIV transmission as a means of bringing about a sustainable change in the incidence of AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1999

An age-period-cohort analysis of 50,875 AIDS cases among injecting drug users in Europe.

BACKGROUND: The long average incubation time from HIV infection to AIDS makes it difficult to estimate recent HIV transmission from AIDS incidence data. Age-period-cohort (APC) analysis can separate out the effects of age, calendar time and birth cohort to provide a clearer picture of transmission trends. METHODS: AIDS incidence data from 1981 to 1994 among intravenous drug users (IDU) for 12 Western European countries were used. Yearly incidences per 100,000 population or 100,000 person-years were calculated by age at diagnosis and 5-year birth cohort (1950-1954, 1955-1959, 1960-1964, 1965-1969 and 1970-1974), and corrected for reporting delay. Incidence patterns were compared between birth cohorts and countries. RESULTS: For most countries the impact was greatest on the cohort born 1960-1964. Comparing incidence patterns in the 1965-1969 to 1960-1964 cohorts suggest the epidemic has plateaued at low to intermediate levels in Austria, Greece and the North-Western European countries, and at high levels in France, Italy and Switzerland. For most countries transmission amongst the 1970-1974 as compared to the 1965-1969 cohorts could not be assessed due to small numbers and short follow-up time. In Spain the epidemic was uncontrolled with a high incidence among recent birth cohorts. In Portugal the epidemic was still at an early and expanding phase. CONCLUSIONS: The APC analysis revealed large country differences in the dynamics of the HIV/AIDS epidemic among IDU. Full interpretation of these differences is dependent on information from other sources about the local public health response and trends in drug injecting behaviours. Earlier introduction of the virus and higher prevalence of injecting drug use may explain some of the generally higher incidence in Southern European countries, but the larger part of it is most likely explained by local characteristics of drug users, such as younger age and more frequent sharing of needles and syringes, and a less effective public health response.

Acquired Immunodeficiency Syndrome↗
PubMed1999

The global impact of HIV infection and disease.

Patterns of HIV infection and disease are changing. HIV will soon enter the top five causes of death worldwide and is now believed to cause more deaths than malaria. Commonwealth countries account for around 60% of prevalent HIV infections worldwide. Around half of all global HIV transmissions are to people under 25 years of age. HIV is lowering life expectancy and reversing gains in child survival in east and central Africa. The incidence and prevalence of HIV infection have increased enormously in southern Africa recently. A more generalised pattern of heterosexual HIV transmission is emerging in parts of South and South East Asia. Injecting drug use and related HIV transmission is increasing in resource-poor countries. Countries where HIV prevalence is low but rising and there are high levels of other STIs offer particular opportunities for early intervention, as it is easier to intervene against HIV when it is entering a country than when it has become established. In countries with weak family and social networks there is inadequate care for the increasing numbers of parentless children. HIV is prejudicing tuberculosis control programme in most African countries and will do the same in Asia. AIDS mortality has fallen in industrialised countries but the prevalence of HIV infection and treatment costs are increasing. Countries that have used multisectoral approaches at an early stage and have had political support for HIV prevention early in their epidemics have been able to limit transmission. Others, intervening later, have been able to reduce transmission. Surveillance methods need to adapt to changing patterns of infection and disease.

Global Health↗
PubMed1999

Poor hepatitis B vaccine coverage in injecting drug users: England, 1995 and 1996.

Self-reported data on vaccination status collected in 1995 and 1996 from seven of the 39 drug agencies in England that took part in the unlinked anonymous HIV prevalence monitoring programme of injecting drug users were analysed to estimate hepatitis B vaccine coverage in this population. Twenty-seven per cent (374/1366) of injecting drug users (IDUs) reported vaccination against hepatitis B and 13% (172) reported having received three doses of vaccine. Eighteen per cent of the IDUs who reported vaccination (66/374) were found to have a marker in their saliva of past/current hepatitis B infection (antibody to hepatitis B core (anti-HBc)) compared with 23% (232/992) of those unvaccinated. Over half (760/1366) of all IDUs tested reported not having been vaccinated against hepatitis B were negative for anti-HBc, and therefore remained susceptible to infection. Targeted vaccination for IDUs against hepatitis B in England has had little success so far, suggesting that enhanced or alternative strategies need to be adopted.

Adolescent↗
PubMed1998

A birth cohort analysis of AIDS in Europe: high incidence among young persons at risk.

OBJECTIVES: To study trends in AIDS incidence in Europe by age and year of birth. DESIGN: Age-period-cohort analyses were adopted to distinguish the different time factors of calendar year, age and year of birth. METHODS: Non-aggregate AIDS incidence data from 12 European countries (1978-1994) were adjusted for reporting delay and expressed per unit of population (per 100000 persons or 100000 person-years). Age-specific incidence patterns (absolute level and rate of increase) were compared between 5-year birth cohorts for homo-/bisexual men, injecting drug users (IDU) and heterosexual contact cases. RESULTS: Mean age at diagnosis increased strongly amongst IDU, but less so among homo-/bisexual men and heterosexual contact cases. Of a total 110646 reported cases (116311 after adjustment for reporting delay), 87167 (78.8%) were among people born in 1950-1974 [91951 (79.1%) after adjustment for reporting delay]. The relative impact on specific birth cohorts differed strongly by exposure group. Incidences at age ranges of 20-24 and 25-29 years among cohorts born in 1965 and after were about the same level (homo-/bisexual men, IDU) or higher (heterosexual contact cases) than older birth cohorts when these were in the same age range; rates of increase were less among homo-/bisexual men and IDU, but higher among heterosexuals. There were large differences between counties. CONCLUSIONS: Overall, AIDS incidence among cohorts born in 1965 and after is about the same level (homo-/bisexual men, IDU) or higher (heterosexual contact cases) than older cohorts when these were in the same age range. Rates of increase of AIDS incidence curves suggest reduced HIV transmission amongst the most recent cohorts of homo-/bisexual men and IDU, but among young heterosexuals the epidemic is still expanding.

Acquired Immunodeficiency Syndrome↗
PubMed1998

The risk of infection with HIV and hepatitis B in individuals who inject steroids in England and Wales.

Data on injecting anabolic steroid users, within the national Unlinked Anonymous HIV Prevalence Monitoring Survey of injecting drug users (IDUs) were analysed to determine their risk of acquiring blood borne viruses. One hundred and forty-nine participants who had injected anabolic steroids in the previous month were identified from 1991-6, contributing 1.4% of all participation episodes in the survey. Rates of needle and syringe sharing by steroid users were low. Three of the 149 (2.0%) had anti-HBc and none had anti-HIV in their salivary specimens. The prevalence of anti-HBc in steroid injectors was significantly lower than in heroin injectors, 275/1509 (18%) (P < 0.001), or in amphetamine injectors, 28/239 (12%) (P < 0.001). The risk of blood borne virus transmission amongst these steroid injectors is low, probably due to hygienic use of injecting equipment and low levels of sharing. It is important to distinguish steroid injectors from other IDUs because they are a distinct group in terms of lifestyle and injecting practice.

Adolescent↗
PubMed1998

Indirect methods for estimating prevalent HIV infections: adults in England and Wales at the end of 1993.

Two indirect methods were used to estimate the point prevalence of HIV infection in England and Wales at the end of 1993 using data on diagnosed HIV infections, AIDS cases, HIV-related deaths and HIV testing behaviour from unlinked anonymous surveys. The methods estimated the proportion of all prevalent HIV infections that diagnosed infections represented. Most of those exposed to HIV infection through injecting drug use or sexual intercourse between men had had their infections diagnosed compared to less than half of those exposed through heterosexual intercourse. The total estimated number of prevalent infections was 22,350 for the diagnosis interval method and 20,540 for the test history method, and about 56-57% of these were in homo/bisexual men. These indirect methods are cheap and simple applications of surveillance data which provide estimates that compare favourably with those produced by more complex methods.

England↗
PubMed1998

Unusual HIV transmissions through blood contact: analysis of cases reported in the United Kingdom to December 1997.

It is important to establish the likely route of infection for all reported HIV infected individuals if the HIV epidemic is to be understood. Investigating routes of infection may bring unusual infection routes to light. Steps have been taken in the United Kingdom (UK) to establish the likely mode of HIV acquisition for everyone reported as infected. If an initial report is incomplete the clinician caring for the patient is asked for relevant information. If further information is needed, and an interview is feasible and acceptable to both the clinician and the patient, information is collected from the patient through face-to-face semistructured interview. Such follow up has identified 19 cases (among 34,000 records of individuals with HIV and/or AIDS for which probable routes of infection have established) who seem to have acquired HIV infection in unusual circumstances. Seven of the 19 cases described in this paper are thought to have acquired HIV infection in the UK, two in Spain, and ten in countries with a high prevalence of HIV infection. This paper describes the circumstances in which HIV transmission is believed to have occurred.

Adult↗
PubMed1997

A Markov model for HIV disease progression including the effect of HIV diagnosis and treatment: application to AIDS prediction in England and Wales.

Back-calculation is a widely used method to estimate HIV incidence rates, and is commonly based on times of AIDS diagnosis. Following up earlier work, we extend this method to also incorporate knowledge of times of HIV diagnosis (first positive test). This is achieved through the use of a Markov model which describes the progress of an HIV infected person through various stages, and which allows causal connections between events to be explicitly modelled. Estimation is based on maximum likelihood, the likelihood being calculated within a discretized version of the Markov model. The effect of sampling uncertainty and model uncertainty (sensitivity) is evaluated simultaneously by means of a combined bootstrap and simulation procedure. At each replication we resample both the data and the model (from a set of possible models described by randomizing one or more parameters). For instance, uncertain knowledge about the incubation distribution affects the estimates of some parameters, but not others. The Markov approach is applied to the prediction of AIDS incidence for homosexuals in England and Wales up to the year 2000.

AIDS Serodiagnosis↗