HIV care cost in England: a cross-sectional analysis of antiretroviral treatment and the impact of generic introduction.

OBJECTIVES: Reliable and timely HIV care cost estimates are important for policy option appraisals of HIV treatment and prevention strategies. As HIV clinical management and outcomes have changed, we aimed to update profiles of antiretroviral (ARV) usage pattern, patent/market exclusivity details and management costs in adults (≥ 18 years old) accessing HIV specialist care in England. METHODS: The data reported quarterly to the HIV and AIDS Reporting System in England was used to identify ARV usage pattern, and were combined with British National Formulary (BNF) prices, non-ARV care costs and patent/market exclusivity information to generate average survival-adjusted lifetime care costs. The cumulative budget impact from 2018 to the year in which all current ARVs were expected to lose market exclusivity was calculated for a hypothetical 85 000 (± 5000) person cohort, which provided an illustration of potential financial savings afforded by bioequivalent generic switches. Price scenarios explored BNF70 (September 2015) prices and generics at 10/20/30/50% of proprietary prices. The analyses took National Health Service (NHS) England's perspective (as the payer), and results are presented in 2016/2017 British pounds. RESULTS: By 2033, most currently available ARVs would lose market exclusivity; that is, generics could be available. Average per person lifetime HIV cost was ~£200 000 (3.5% annual discount) or ~£400 000 (undiscounted), reducing to ~£70 000 (3.5% annual discount; ~£120 000 undiscounted) with the use of generics (assuming that generics cost 10% of proprietary prices). The cumulative budget to cover 85 000 (± 5000) persons for 16 years (2018-2033) was £10.5 (± 0.6) billion, reducing to £3.6 (± 0.2) billion with the use of generics. CONCLUSIONS: HIV management costs are high but financial efficiency could be improved by optimizing generic use for treatment and prevention to mitigate the high cost of lifelong HIV treatment. Earlier implementation of generics as they become available offers the potential to maximize the scale of the financial savings.

HIV incidence in an open national cohort of men who have sex with men attending sexually transmitted infection clinics in England.

OBJECTIVES: The aim of the study was to determine HIV incidence among men who have sex with men (MSM) who repeat test for HIV at sexually transmitted infection (STI) clinics in England, and identify associated factors. METHODS: Annual HIV incidence and 95% confidence interval (CI) were calculated for a national cohort of MSM who tested HIV negative at any STI clinic in England in 2012 and had a follow-up test within 1 year using routinely collected data. Cox regression analyses were performed to identify predictors of HIV acquisition and population attributable risk for HIV infection was calculated for predictors. RESULTS: In 2012, 85 500 MSM not known to be HIV positive attended any STI clinic in England, and 31% tested for HIV at least twice within 1 year at the same clinic. HIV incidence was 2.0 per 100 person-years (PY; 95% CI 1.8-2.2) among repeat testers. Incidence was higher among MSM of black ethnicity (3.2 per 100 PY) and those with a bacterial STI diagnosis at the initial attendance (3.2 per 100 PY). MSM with a previous syphilis or gonorrhoea infection were at significantly greater risk of acquiring HIV in the subsequent year [adjusted hazard ratio 4.1 (95% CI 2.0-8.3) and 2.1 (95% CI 1.4-3.2), respectively]. The predictors accounted for 37% of HIV infections. CONCLUSIONS: Annual HIV incidence among MSM attending STI clinics in England is high. Previous STIs were predictors of HIV acquisition but only accounted for one in five infections. More discriminatory behavioural predictors of HIV acquisition could provide better triaging of HIV prevention services for MSM attending STI clinics.

Sex, drugs and smart phone applications: findings from semistructured interviews with men who have sex with men diagnosed with Shigella flexneri 3a in England and Wales.

OBJECTIVES: To inform control strategies undertaken as part of an outbreak of Shigella flexneri 3a among men who have sex with men (MSM). METHODS: All men aged ≥18 years diagnosed with S flexneri 3a between October 2012 and May 2013 were invited to participate. Semistructured in-depth quantitative interviews were conducted to explore lifestyle and sexual behaviour factors. RESULTS: Of 53 men diagnosed, 42 were interviewed of whom 34 were sexually active MSM. High numbers of sexual partners were reported (median=22) within the previous year; most were casual encounters met through social media networking sites (21/34). 63% (20/32) were HIV-positive and actively sought positive partners for condomless sex. 62% (21/34) of men had used chemsex drugs (mephedrone, crystal methamphetamine and γ-butyrolactone/γ-hydroxybutrate), which facilitate sexually disinhibiting behaviour during sexual encounters. 38% (8/21) reported injecting chemsex drugs. Where reported almost half (12/23) had attended or hosted sex parties. All reported oral-anal contact and fisting was common (16/34). Many had had gonorrhoea (23/34) and chlamydia (17/34). HIV-positive serostatus was associated with both insertive anal intercourse with a casual partner and receptive fisting (adjusted OR=15.0, p=0.01; adjusted OR=18.3, p=0.03) as was the use of web applications that promote and facilitate unprotected sex (adjusted OR=19.8, p=0.02). CONCLUSIONS: HIV-positive MSM infected with S flexneri 3a used social media to meet sexual partners for unprotected sex mainly at sex parties. The potential for the transmission of S flexneri, HIV and other infections is clear. MSM need to be aware of the effect that chemsex drugs have on their health.

Recent infection testing algorithm (RITA) applied to new HIV diagnoses in England, Wales and Northern Ireland, 2009 to 2011.

In 2009, Public Health England (PHE) introduced the routine application of a recent infection testing algorithm (RITA) to new HIV diagnoses, where a positive RITA result indicates likely acquisition of infection in the previous six months. Laboratories submit serum specimens to PHE for testing using the HIV 1/2gO AxSYM assay modified for the determination of HIV antibody avidity. Results are classified according to avidity index and data on CD4 count, antiretroviral treatment and the presence of an AIDS-defining illness. Between 2009 and 2011, 38.4% (6,966/18,134) of new HIV diagnoses in England, Wales and Northern Ireland were tested. Demographic characteristics of those tested were similar to all persons with diagnosed HIV. Overall, recent infection was 14.7% (1,022/6,966) and higher among men who have sex with men (MSM) (22.3%, 720/3,223) compared with heterosexual men and women (7.8%, 247/3,164). Higher proportions were among persons aged 15-24 years compared with those ≥50 years (MSM 31.2% (139/445) vs 13.6% (42/308); heterosexual men and women 17.3% (43/249) vs 6.2% (31/501)). Among heterosexual men and women, black Africans were least likely to have recent infection compared with whites (4.8%, 90/1,892 vs 13.3%, 97/728; adjusted odds ratio: 0.6; 95% CI: 0.4-0.9). Our results indicate evidence of ongoing HIV transmission during the study period, particularly among MSM.

HIV treatment as prevention among men who have sex with men in the UK: is transmission controlled by universal access to HIV treatment and care?

OBJECTIVES: In the UK, free HIV care is provided through dedicated HIV clinics. Using the national cohort of men who have sex with men (MSM) with diagnosed HIV infection and estimates of the number of undiagnosed men, we assessed whether high retention in HIV care and treatment coverage is sufficient to reduce HIV transmission. METHODS: Antiretroviral therapy (ART) uptake and viral load distribution among diagnosed men were analysed by treatment status and CD4 count for the period between 2006 and 2010. A multi-parameter evidence synthesis (MPES) method was used to estimate the size of the undiagnosed population. The viral load distribution among newly diagnosed untreated men was applied to the undiagnosed population. Infectivity was defined as a viral load > 1500 HIV-1 RNA copies/mL. RESULTS: Between 2006 and 2010, ART coverage among all HIV-infected MSM (diagnosed and undiagnosed) increased from 49 to 60%, while the proportion of infectious men fell from 47 to 35%. Over the same period, the number of all HIV-infected MSM increased from 30,000 to 40,100 and the number of infectious MSM remained stable at 14,000. Of the 14,000 infectious MSM in 2010, 62% were undiagnosed, 33% were diagnosed but untreated, and 5% received ART. Extending ART to all diagnosed HIV-infected MSM with CD4 counts < 500 cells/µL in 2010 would have reduced the overall proportion of infectious men from 35 to 29% and halving the proportion who were undiagnosed would further have reduced this to 21%. CONCLUSIONS: High ART coverage in the UK has reduced the infectivity of the HIV-diagnosed population. However, the effectiveness of treatment as prevention will be limited unless the undiagnosed population is reduced through frequent HIV testing and consistent condom use.

Bayesian evidence synthesis for a transmission dynamic model for HIV among men who have sex with men.

Understanding infectious disease dynamics and the effect on prevalence and incidence is crucial for public health policies. Disease incidence and prevalence are typically not observed directly and increasingly are estimated through the synthesis of indirect information from multiple data sources. We demonstrate how an evidence synthesis approach to the estimation of human immunodeficiency virus (HIV) prevalence in England and Wales can be extended to infer the underlying HIV incidence. Diverse time series of data can be used to obtain yearly "snapshots" (with associated uncertainty) of the proportion of the population in 4 compartments: not at risk, susceptible, HIV positive but undiagnosed, and diagnosed HIV positive. A multistate model for the infection and diagnosis processes is then formulated by expressing the changes in these proportions by a system of differential equations. By parameterizing incidence in terms of prevalence and contact rates, HIV transmission is further modeled. Use of additional data or prior information on demographics, risk behavior change and contact parameters allows simultaneous estimation of the transition rates, compartment prevalences, contact rates, and transmission probabilities.

The risk of variant Creutzfeldt-Jakob disease among UK patients with bleeding disorders, known to have received potentially contaminated plasma products.

The risk of variant Creutzfeldt-Jakob disease (vCJD) from potentially infected plasma products remains unquantified. This risk has been assessed for 787 UK patients with an inherited bleeding disorder prospectively followed-up for 10-20 years through the UK Haemophilia Centre Doctors' Organisation (UKHCDO) Surveillance Study. These patients had been treated with any of 25 'implicated' clotting factor batches from 1987 to 1999, which included in their manufacture, plasma from eight donors who subsequently developed clinical vCJD. Variant CJD infectivity of these batches was estimated using plasma fraction infectivity estimates and batch-manufacturing data. Total potential vCJD infectivity received by each patient has been estimated by cumulating estimated infectivity from all doses received during their lifetime. Of 787 patients, 604 (77%) were followed-up for over 13 years following exposure to an implicated batch. For these 604 patients, the estimated vCJD risk is ≥ 1% for 595, ≥ 50% for 164 and 100% for 51. This is additional to background UK population risk due to dietary exposure. Of 604 patients, 94 (16%) received implicated batches linked to donors who developed clinical vCJD within 6 months of their donations. One hundred and fifty-one (25%) had received their first dose when under 10 years of age. By 1st January 2009, none of these patients had developed clinical vCJD. The absence of clinical vCJD cases in this cohort to date suggests that either plasma fraction infectivity estimates are overly precautionary, or the incubation period is longer for this cohort than for implicated cellular blood product recipients. Further follow-up of this cohort is needed.

Prevalence of markers for HIV, hepatitis B and hepatitis C infection in UK military recruits.

An unlinked anonymous survey was conducted to measure the prevalence of selected markers for HIV, hepatitis B and C infection in recruits to the UK Armed Forces to inform future screening and hepatitis B vaccination policies. During 2007, nearly 14 000 left-over samples taken from new recruits for blood typing were collected, unlinked from identifiers and anonymously tested for HIV, hepatitis C and current and past cleared hepatitis B infection. Overall, serological evidence of HIV and hepatitis C was found in 0·06% and 0·06% of recruits, respectively. Evidence of past cleared and current hepatitis B infection was found in 3·63% and 0·37% of recruits, respectively. Overall, prevalence rates were broadly consistent with UK population estimates of infection. However, HIV and hepatitis B prevalence was higher in recruits of African origin than in those from the UK (P<0·0001). Screening for these infections is an option that could be considered for those entering Services from high-prevalence countries.

Implications for HIV testing policy derived from combining data on voluntary confidential testing with viral sequences and serological analyses.

OBJECTIVES: Laboratory, clinical and sequence-based data were combined to assess the differential uptake of voluntary confidential HIV testing (VCT) according to risk and explore the occurrence of HIV transmission from individuals with recently acquired HIV infection, before the diagnostic opportunity. METHODS: Between 1999 and 2002, nearly 30,000 anonymous tests for previously undiagnosed HIV infection were conducted among men who have sex with men (MSM) attending 15 sentinel sexually transmitted infection (STI) clinics in England, Wales and Northern Ireland. Using a serological testing algorithm, undiagnosed HIV-infected men were categorised into those with recent and non-recent infection. VCT uptake was compared between HIV-negative, recently HIV-infected and non-recently HIV-infected men. A phylogenetic analysis of HIV pol sequences from 127 recently HIV-infected MSM was conducted to identify instances in which transmission may have occurred before the diagnostic opportunity. RESULTS: HIV-negative MSM were more likely to receive VCT at clinic visits compared with undiagnosed HIV-infected MSM (56% (14,020/24,938) vs 31% (335/1072); p<0.001). Recently HIV-infected MSM were more likely to receive VCT compared with those with non-recent infections (42% (97/229) vs 28% (238/844); p<0.001). 22% (95/425) of undiagnosed HIV-infected MSM with STI received VCT. Phylogenetic analysis revealed at least seven transmissions may have been generated by recently HIV-infected MSM: a group that attended STI clinics soon after seroconversion. CONCLUSIONS: The integration of clinical, laboratory and sequence-based data reveals the need for specific targeting of the recently HIV exposed, and those with STI, for VCT. VCT promotion alone may be limited in its ability to prevent HIV transmission.

Epidemiology of herpes simplex virus types 2 and 1 amongst men who have sex with men attending sexual health clinics in England and Wales: implications for HIV prevention and management.

The objective was to investigate herpes simplex virus (HSV) epidemiology amongst HIV-positive and HIV-negative men who have sex with men (MSM) in England and Wales. Unlinked anonymous sera from 3,968 MSM attending 12 sexual health clinics in 2003 were tested for HIV, HSV-2 and HSV-1 antibodies. Fifty-five percent of HIV-positive MSM were HSV-2-seropositive, compared to 17% of HIV-negative MSM (Adj RR: 2.14 [CI: 1.92-2.37]). Amongst HIV-positive individuals, there was no significant difference in HSV-2 seroprevalence by knowledge of HIV status or whether the HIV infection was recently acquired (determined through STARHS). HIV infection was also independently associated with HSV-1 serostatus (Adj RR 1.19 [CI: 1.14-1.24)]). Four of the twelve attendees who received a diagnosis of recurrent anogenital herpes at the clinic visit were HSV-1-seropositive but not HSV-2-seropositive at the time, although no cultures or PCR results were available to type the cause of the ano-genital presenting disease. It is of concern that one in two HIV-positive MSM and one in six HIV-negative MSM may be infected with HSV-2, given increasing evidence of its impact on HIV progression, onward transmission and acquisition. To date results have been disappointing from trials aimed at reducing HIV onward transmission and HIV acquisition using HSV antiviral medication. However, recent research in an African context demonstrates the efficacy of HSV antivirals in delaying HIV progression. The high prevalence of HSV-2 amongst HIV-positive MSM suggests that an increased focus on HSV control in the management of HIV amongst MSM in the United Kingdom may be warranted. Given this and existing research on the high prevalence of genitally acquired HSV-1 amongst MSM in the UK, further research is also warranted into the role of HSV-1 in the HIV epidemic in this context.

The cost-effectiveness of screening and treatment for hepatitis C in prisons in England and Wales: a cost-utility analysis.

Prisoners have a high prevalence of hepatitis C virus (HCV) infection compared with the general population in England and Wales and in many locations throughout the world. This is because of large numbers of injecting drug users that engage in behaviours likely to transmit HCV being present within prison populations. It is, therefore, suggested that prison may be an appropriate location for HCV screening and treatment to be administered. Using cost-utility analysis, this study considers the costs and benefits of administering a single round of screening on reception into prison to all individuals followed by possible later screening in the community and comparing this to individuals who may only be tested and treated in the community at a later date. The cost/QALY of one round of prison testing and treatment was found to be 54,852 pounds sterling, although probabilistic sensitivity analysis showed extensive uncertainty about this estimate. One-way sensitivity analysis revealed the importance of the parameters describing the progression of chronic HCV and the discount rates. While the results presented here at baseline would suggest that screening and treatment for HCV in prisons is not cost-effective, these results are subject to much uncertainty. The importance of the rates describing the progression of chronic HCV on the cost-effectiveness of this intervention has been demonstrated and this suggests that future work should be undertaken to gain further insight into the rates that individuals progress to the later stages of chronic HCV infection.

Sexual behaviours and sexually transmitted infection outcomes in a cohort of HIV-negative men who have sex with men attending sexual health clinics in England.

Men who have sex with men (MSM) attending sexual health (SH) clinics are at high risk for HIV acquisition and are disproportionately affected by sexually transmitted infections (STIs). We collected standardised behavioural data from MSM attending clinics to characterise sexual behaviours and identify predictors for HIV and STIs. In 2012­2013, HIV-negative MSM attending five SH clinics in England reported sexual behaviours in the previous three months via a self-administered questionnaire. Behaviours were linked to the individual's clinical records using national surveillance. The prevalence and incidence of bacterial STIs (gonorrhoea, Chlamydia, lymphogranuloma venereum and syphilis) and incidence of HIV were calculated. Adjusted odds ratios and hazard ratios with 95% confidence interval (CI) were reported for significant predictors. Of 1278 HIV-negative MSM, 54% were of white ethnicity and UK-born and 43% were 25­34 years old. Almost all men reported at least one partner in the last three months. Half reported condomless anal sex and 36% condomless receptive anal intercourse (CRAI). Incidence of bacterial STIs was 46/100 (95%CI 39­54) person years (py) and of HIV was 3.1/100 (95%CI 1.7­5.6) py. A STI at baseline and CRAI with increasing numbers of partners were associated with both incident infections. In this cohort of MSM high-risk behaviours and STIs were prevalent. Engagement in CRAI increased the likelihood of subsequent infection, while men diagnosed with a bacterial STI were at increased risk of a future STI. Clinical and behavioural risk assessments to determine an individual's risk of infection could allow a more nuanced prevention approach that has greater success in reducing transmission.

Modelling the force of infection for hepatitis B and hepatitis C in injecting drug users in England and Wales.

BACKGROUND: Injecting drug use is a key risk factor, for several infections of public health importance, especially hepatitis B (HBV) and hepatitis C (HCV). In England and Wales, where less than 1% of the population are likely to be injecting drug users (IDUs), approximately 38% of laboratory reports of HBV, and 95% of HCV reports are attributed to injecting drug use. METHODS: Voluntary unlinked anonymous surveys have been performed on IDUs in contact with specialist agencies throughout England and Wales. Since 1990 more than 20,000 saliva samples from current IDUs have been tested for markers of infection for HBV, HCV testing has been included since 1998. The analysis here considers those IDUs tested for HBV and HCV (n = 5,682) from 1998-2003. This study derives maximum likelihood estimates of the force of infection (the rate at which susceptible IDUs acquire infection) for HBV and HCV in the IDU population and their trends over time and injecting career length. The presence of individual heterogeneity of risk behaviour and background HBV prevalence due to routes of transmission other than injecting are also considered. RESULTS: For both HBV and HCV, IDUs are at greatest risk from infection in their first year of injecting (Forces of infection in new initiates 1999-2003: HBV = 0.1076 95% C.I: 0.0840-0.1327 HCV = 0.1608 95% C.I: 0.1314-0.1942) compared to experienced IDUs (Force of infection in experienced IDUs 1999-2003: HBV = 0.0353 95% C.I: 0.0198-0.0596, HCV = 0.0526 95% C.I: 0.0310-0.0863) although independently of this there is evidence of heterogeneity of risk behaviour with a small number of IDUs at increased risk of infection. No trends in the FOI over time were detected. There was only limited evidence of background HBV infection due to factors other than injecting. CONCLUSION: The models highlight the need to increase interventions that target new initiates to injecting to reduce the transmission of blood-borne viruses. Although from the evidence here, identification of those individuals that engage in heightened at-risk behaviour may also help in planning effective interventions. The data and methods described here may provide a baseline for monitoring the success of public health interventions.

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.

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.

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.

An investigation assessing the fraction of human immunodeficiency virus infection attributable to ethnic group variations in risk.

Considerable speculation and a recent publication has suggested that much of the human immunodeficiency virus (HIV-1) infection in the subset of the UK population represented by women having babies in Metropolitan London is substantially imported from Africa. Other data are supportive of this hypothesis. Ades et al. (1992) concluded that the fraction of HIV seroprevalence, identified in a large London-based study using neonatal blood from the dried blood spots on Guthrie cards, attributable to mothers born in Africa was 92.4% with 95% CI: 82-100%. This is an important observation which requires confirmation. This paper reports on an attempt to do this with closely similar methodology using the Unlinked Anonymous Survey (UAS) of HIV-1 seroprevalence in pregnant women attending antenatal centres, together with data from the Office of Population Censuses and Surveys (OPCS) on the country of origins of mothers delivering in 1991 at the 15 London centres included in the UAS. As in Ades' analysis there appeared to be a strong association between centre prevalences and the proportions of women of African origin delivering at those centres. This was consistent with a high fraction of seroprevalence attributable to such women, but it was also clear that the assumptions required for the estimation of the attributable fractions were not fully met. Analyses modified to justify the assumptions produced attributable fraction estimates ranging from 44% to 96% with lower 95% confidence limits 20% or less.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

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.

An outbreak of serious illness and death among injecting drug users in England during 2000.

An outbreak of serious illness and death occurred in injecting drug users during 2000 in Scotland, Ireland and England. National and international collaboration was necessary for the investigation and management of this outbreak. In England and Wales active case-finding was initiated, coupled with standardised data collection and microbiological investigation of cases. Twenty-six definite or probable cases were identified in England between 1 April and 31 Aug. 2000; 17 of these occurred in the North. The overall case fatality was 50% (13/26). The principal apparent risk factor was a history of intramuscular or subcutaneous injection of heroin and the limited duration of the outbreak suggested that the problem might have been related to a particular supply of heroin. Clostridium novyi was isolated from two English cases. Taken in conjunction with contemporaneous microbiological and epidemiological results from Scottish and Irish cases, the probable aetiology for this outbreak was infection with C. novyi associated with both a particular supply of heroin and the method of preparation and injection used. A 'toolkit' was distributed in Sept. 2000 to all Consultants for Communicable Disease Control in England and Wales to assist them with the ongoing surveillance, investigation and management of this condition. Lessons learned have been used to produce guidance for the investigation and management of outbreaks of unexplained serious illness of possible infective aetiology.