Noel Gill | London School of Hygiene & Tropical Medicine (original) (raw)

Papers by Noel Gill

Eurosurveillance, Dec 4, 2008

Journal of the Royal Statistical Society, 1998

Since the late 1980s, regular monitoring of the human immunode®ciency virus epidemic in England a... more Since the late 1980s, regular monitoring of the human immunode®ciency virus epidemic in England and Wales has been carried out through the work of successive national working groups. One of their tasks has been to provide short-term projections of the incidence of acquired immune de®ciency syndrome. In this paper the data and methods used in this projection work are reviewed and results critically assessed with the aim of highlighting the strong interaction between methodological developments and data acquisition.

Epidemiology and Infection, Mar 17, 2008

Since 2001 hepatitis B vaccination has been offered to prisoners on reception into prisons in Eng... more Since 2001 hepatitis B vaccination has been offered to prisoners on reception into prisons in England and Wales. However, short campaigns of vaccinating the entire population of individual prisons have achieved high vaccination coverage for limited periods, suggesting that short campaigns may be a preferable way of vaccinating prisoners. A model is used that describes the flow of prisoners through prisons stratified by injecting status to compare a range of vaccination scenarios that describe vaccination on prison reception or via regular short campaigns. Model results suggest that vaccinating on prison reception can capture a greater proportion of the injecting drug user (IDU) population than the comparable campaign scenarios (63 % vs. 55. 6% respectively). Vaccination on prison reception is also more efficient at capturing IDUs for vaccination than vaccination via a campaign, although vaccination via campaigns may have a role with some infections for overall control.

Surveillance of listeriosis in Navarre, Spain, 1995-2005 – epidemiological patterns and character... more Surveillance of listeriosis in Navarre, Spain, 1995-2005 – epidemiological patterns and characterisation of clinical and food isolates 16

Sexually Transmitted Infections, 2017

Introduction Men who have sex with men (MSM) remain at highest risk of HIV acquisition in England... more Introduction Men who have sex with men (MSM) remain at highest risk of HIV acquisition in England. We assessed recent national trends in HIV diagnoses and tests among MSM attending specialist sexual health clinics (SHCs) in England. Methods Numbers of HIV diagnoses and tests in MSM were obtained from GUMCADv2, the national surveillance system for sexually transmitted infections. Trends were stratified by HIV testing history (new/repeat-testers in last 2 years) and service location (London/Outside-London). Student’s t-tests were used to assess the differences in mean numbers of HIV diagnoses and tests between Q4/2014–Q3/2015 and Q4/2015–Q3/2016. Results A decline in HIV diagnoses from 515 to 427 (17%) was observed between Q4/2014–Q3/2015 and Q4/2015–Q3/2016 (p=0.05). Greatest declines were in London SHCs (276–209; 24%; p=0.04) and among new-testers (390–308; 21%; p=0.03). In London SHCs, there was a 29% diagnosis decline among new-testers (195–138; p=0.03) with no evidence of a diffe...

Eurosurveillance, 2012

Diagnoses of Shigella flexneri in the United Kingdom (UK) are usually travel-related. However, si... more Diagnoses of Shigella flexneri in the United Kingdom (UK) are usually travel-related. However, since 2009, there has been an overall increase in UK-acquired cases. The Health Protection Agency has been investigating a national outbreak of S. flexneri detected in 2011 and which is still ongoing. Cases occurred mostly in men who have sex with men and were of serotype 3a. The investigation aimed at obtaining epidemiological data to inform targeted outbreak management and control.

Eurosurveillance, 2008

The latest HIV data for 2007 has recently been published for the United Kingdom (UK). During the ... more The latest HIV data for 2007 has recently been published for the United Kingdom (UK). During the year, an estimated 6,840 (95% confidence intervals 6,600-7,050) persons (adjusted for reporting delays) were newly diagnosed with HIV in the UK. This represents a 12% decline from a peak of new HIV diagnoses reported in 2005 (7,800). Almost all this decline in new HIV diagnoses was in HIV-infected heterosexuals from sub-Saharan Africa who were probably infected in their country of origin.

Sexually Transmitted Infections, 2019

ObjectivesThe size of the population of men who have sex with men (MSM) who may be eligible for H... more ObjectivesThe size of the population of men who have sex with men (MSM) who may be eligible for HIV pre-exposure prophylaxis (HIV-PrEP) in England remains unknown. To plan for a national PrEP implementation trial, we estimated the number of MSM attending sexual health clinics (SHCs) that may be eligible for HIV-PrEP in England.MethodsSexually transmitted infection (STI) surveillance data from 2010 to 2015 from the GUMCAD surveillance system were used to estimate the annual number of HIV-negative MSM who may be eligible for HIV-PrEP in England. Based on national eligibility criteria, we identified HIV-negative MSM attending SHCs with a HIV-negative test in the past year and used diagnosed bacterial STI (past year) in this group as a proxy for condomless sex and eligibility for HIV-PrEP. We estimated HIV incidence per 100 person-years (py) in these groups in 2014.ResultsDuring 2010–2015, the number of HIV-negative MSM attending SHCs with a HIV-negative test in the past year doubled fr...

BackgroundNear 60% of new HIV infections in the United Kingdom are estimated to occur in men who ... more BackgroundNear 60% of new HIV infections in the United Kingdom are estimated to occur in men who have sex with men (MSM). Patterns of mixing between different risk groups of MSM have been suggested to spread the HIV epidemics through age-disassortative partnerships and to contribute to ethnic disparities in infection rates. Understanding these mixing patterns in transmission can help to determine which groups are at a greater risk and guide prevention.MethodsWe analyzed combined epidemiologic data and viral sequences from MSM diagnosed with HIV as of mid-2015 at the national level. We applied a phylodynamic source attribution model to infer patterns of transmission between groups of patients by age, ethnicity and region.ResultsFrom pair probabilities of transmission between 19 847 MSM patients, we found that potential transmitters of HIV subtype B were on average 5 months older than recipients. We also found a moderate overall assortativity of transmission by ethnic group and a stro...

Lifetime Data Analysis, 2019

CD4-based multi-state back-calculation methods are key for monitoring the HIV epidemic, providing... more CD4-based multi-state back-calculation methods are key for monitoring the HIV epidemic, providing estimates of HIV incidence and diagnosis rates by disentangling their interrelated contribution to the observed surveillance data. This paper, extends existing approaches to age-specific settings, permitting the joint estimation of ageand time-specific incidence and diagnosis rates and the derivation of other epidemiological quantities of interest. This allows the identification of specific age-groups at higher risk of infection, which is crucial in directing public health interventions. We investigate, through simulation studies, the suitability of various bivariate splines for the non-parametric modelling of the latent age-and time-specific incidence and illustrate our method on routinely collected data from the HIV epidemic among gay and bisexual men in England and Wales.

Clinical Infectious Diseases, 2018

Phylogenetic reconstruction shows no evidence drug-resistant minority variants (DRMinVs) in patie... more Phylogenetic reconstruction shows no evidence drug-resistant minority variants (DRMinVs) in patients with recent HIV-1 infection result from a transmission event. Therefore the majority of DRMinVs in people recently infected are most likely generated de novo.

BMC Medicine, 2018

Background: The UK, like a number of other countries, has a refugee resettlement programme. Exter... more Background: The UK, like a number of other countries, has a refugee resettlement programme. External factors, such as higher prevalence of infectious diseases in the country of origin and circumstances of travel, are likely to increase the infectious disease risk of refugees, but published data is scarce. The International Organization for Migration carries out and collates data on standardised pre-entry health assessments (HA), including testing for infectious diseases, on all UK refugee applicants as part of the resettlement programme. From this data, we report the yield of selected infectious diseases (tuberculosis (TB), HIV, syphilis, hepatitis B and hepatitis C) and key risk factors with the aim of informing public health policy. Methods: We examined a large cohort of refugees (n = 18,418) who underwent a comprehensive pre-entry HA between March 2013 and August 2017. We calculated yields of infectious diseases stratified by nationality and compared these with published (mostly WHO) estimates. We assessed factors associated with case positivity in univariable and multivariable logistic regression analysis. Results: The number of refugees included in the analysis varied by disease (range 8506-9759). Overall yields were notably high for hepatitis B (188 cases; 2.04%, 95% CI 1.77-2.35%), while yields were below 1% for active TB (9 cases; 92 per 100,000, 48-177), HIV (31 cases; 0.4%, 0.3-0.5%), syphilis (23 cases; 0.24%, 0.15-0.36%) and hepatitis C (38 cases; 0.41%, 0.30-0.57%), and varied widely by nationality. In multivariable analysis, sub-Saharan African nationality was a risk factor for several infections (HIV:

The Journal of infectious diseases, Jan 23, 2018

The impact of HIV pre-exposure prophylaxis (PrEP) depends on infections averted by protecting vul... more The impact of HIV pre-exposure prophylaxis (PrEP) depends on infections averted by protecting vulnerable individuals as well as infections averted by preventing transmission by those who would have been infected if not receiving PrEP. Analysis of HIV phylogenies reveals risk factors for transmission, which we examine as potential criteria for allocating PrEP. We analyzed 6912 HIV-1 partial pol sequences from men who have sex with men (MSM) in the United Kingdom combined with global reference sequences and patient-level metadata. Population genetic models were developed that adjust for stage of infection, global migration of HIV lineages, and changing incidence of infection through time. Models were extended to simulate the effects of providing susceptible MSM with PrEP. We found that young age <25 years confers higher risk of HIV transmission (relative risk = 2.52 [95% confidence interval, 2.32-2.73]) and that young MSM are more likely to transmit to one another than expected by ...

Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin, 2017

Four isolated cases of congenital syphilis born to mothers who screened syphilis negative in the ... more Four isolated cases of congenital syphilis born to mothers who screened syphilis negative in the first trimester were identified between March 2016 and January 2017 compared with three cases between 2010 and 2015. The mothers were United Kingdom-born and had no syphilis risk factors. Cases occurred in areas with recent increases in sexually-transmitted syphilis among women and men who have sex with men, some behaviourally bisexual, which may have facilitated bridging between sexual networks.

HIV Medicine, 2017

ObjectivesThe aim of the study was to determine HIV incidence among men who have sex with men (MS... more ObjectivesThe 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.MethodsAnnual 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.ResultsIn 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 attendan...

Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin, Jan 22, 2017

Since October 2015 up to September 2016, HIV diagnoses fell by 32% compared with October 2014-Sep... more Since October 2015 up to September 2016, HIV diagnoses fell by 32% compared with October 2014-September 2015 among men who have sex with men (MSM) attending selected London sexual health clinics. This coincided with high HIV testing volumes and rapid initiation of treatment on diagnosis. The fall was most apparent in new HIV testers. Intensified testing of high-risk populations, combined with immediately received anti-retroviral therapy and a pre-exposure prophylaxis (PrEP) programme, may make elimination of HIV achievable.

BMC Infectious Diseases, 2006

Background: Injecting drug use is a key risk factor, for several infections of public health impo... more 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.

AIDS, 2015

Background: Increased rates of testing, with early antiretroviral therapy (ART) initiation, repre... more Background: Increased rates of testing, with early antiretroviral therapy (ART) initiation, represent a key potential HIV-prevention approach. Currently, in MSM in the United Kingdom, it is estimated that 36% are diagnosed by 1 year from infection, and the ART initiation threshold is at CD4 þ cell count 350/ml. We investigated what would be required to reduce HIV incidence in MSM to below 1 per 1000 person-years (i.e. <535 new infections per year) by 2030, and whether this is likely to be costeffective. Methods: A dynamic, individual-based simulation model was calibrated to multiple data sources on HIV in MSM in the United Kingdom. Outcomes were projected according to future alternative HIV testing and ART initiation scenarios to 2030, considering also potential changes in levels of condomless sex. Results: For ART use to result in an incidence of close to 1/1000 person-years requires the proportion of all HIV-positive MSM with viral suppression to increase from below 60% currently to 90%, assuming no rise in levels of condomless sex. Substantial increases in HIV testing, such that over 90% of men are diagnosed within a year of infection, would increase the proportion of HIV-positive men with viral suppression to 80%, and it would be 90%, if ART is initiated at diagnosis. The scenarios required for such a policy to be cost-effective are presented. Conclusion: This analysis provides targets for the proportion of all HIV-positive MSM with viral suppression required to achieve substantial reductions in HIV incidence.

Sexually Transmitted Infections, 2015