Isabel Oliver

University of Bristol, Bristol, England, United Kingdom

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Publications (33)165.14 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: 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.
    Sexually Transmitted Infections 04/2015; DOI:10.1136/sextrans-2014-051659 · 3.08 Impact Factor
  • Perspectives in Public Health 09/2014; 134(5):289-292. · 1.09 Impact Factor
  • Perspectives in Public Health 09/2014; 134(5):297-299. DOI:10.1177/1757913914547331 · 1.09 Impact Factor
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    ABSTRACT: In January-March 2013 in England, confirmed measles cases increased in children aged 10-16 years. In April-September 2013, the National Health System and Public Health England launched a national measles-mumps-rubella (MMR) campaign based on data from Child Health Information Systems (CHIS) estimating that approximately 8% in this age group were unvaccinated. We estimated coverage at baseline, and, of those unvaccinated (target), the proportion vaccinated up to 20/08/2013 (mid-point) to inform further public health action. We selected a sample of 6644 children aged 10-16 years using multistage sampling from those reported unvaccinated in CHIS at baseline and validated their records against GP records. We adjusted the CHIS MMR vaccine coverage estimates correcting by the proportion of vaccinated children obtained through sample validation. We validated 5179/6644 (78%) of the sample records. Coverage at baseline was estimated as 94.7% (95% confidence intervals, CI: 93.5-96.0%), lower in London (86.9%, 95%CI: 83.0-90.9%) than outside (96.1%, 95%CI 95.5-96.8%). The campaign reached 10.8% (95%CI: 7.0-14.6%) of the target population, lower in London (7.1%, 95%CI: 4.9-9.3) than in the rest of England (11.4%, 95%CI: 7.0-15.9%). Coverage increased by 0.5% up to 95.3% (95% CI: 94.1-96.4%) but an estimated 210,000 10-16 year old children remained unvaccinated nationally. Baseline MMR coverage was higher than previously reported and was estimated to have reached the 95% campaign objective at midpoint. Eleven per cent of the target population were vaccinated during the campaign, and may be underestimated, especially in London. No further national campaigns are needed but targeted local vaccination activities should be considered.
    Vaccine 07/2014; 32(36). DOI:10.1016/j.vaccine.2014.05.077 · 3.49 Impact Factor
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    ABSTRACT: Transporting over two billion passengers per year, global airline travel has the potential to spread emerging infectious diseases, both via transportation of infectious cases and through in-flight transmission. Current World Health Organization (WHO) guidance recommends contact tracing of passengers seated within two rows of a case of influenza during air travel. The objectives of this study were to describe flight-related transmission of influenza A(H1N1)pdm09 during a commercial flight carrying the first cases reported in the United Kingdom and to test the specific hypothesis that passengers seated within two rows of an infectious case are at greater risk of infection. An historical cohort study, supplemented by contact tracing, enhanced surveillance data and laboratory testing, was used to establish a case status for passengers on board the flight. Data were available for 239 of 278 (86·0%) of passengers on the flight, of whom six were considered infectious in-flight and one immune. The attack rate (AR) was 10 of 232 (4·3%; 95% CI 1·7-6·9%). There was no evidence that the AR for those seated within two rows of an infectious case was different from those who were not (relative risk 0·9; 95% CI 0·2-3·1; P = 1·00). Laboratory testing using PCR and/or serology, available for 118 of 239 (49·4%) of the passengers, was largely consistent with clinically defined case status. This study of A(H1N1)pdm09 does not support current WHO guidance regarding the contact tracing of passengers seated within two rows of an infectious case of influenza during air travel.
    Influenza and Other Respiratory Viruses 01/2014; 8(1):66-73. DOI:10.1111/irv.12181 · 1.90 Impact Factor
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    ABSTRACT: In April 2009, influenza A(H1N1)pdm09 virus infection was confirmed in a person who had been symptomatic while traveling on a commercial flight from Mexico to the United Kingdom. Retrospective public health investigation and contact tracing led to the identification of 8 additional confirmed cases among passengers and community contacts of passengers.
    Emerging Infectious Diseases 01/2014; 20(1):118-20. DOI:10.3201/eid2001.120101 · 7.33 Impact Factor
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    ABSTRACT: Objective To determine if a structured complex intervention increases opportunistic chlamydia screening testing of patients aged 15-24 years attending English general practitioner (GP) practices. Methods A prospective, Cluster Randomised Controlled Trial with a modified Zelen design involving 160 practices in South West England in 2010. The intervention was based on the Theory of Planned Behaviour (TPB). It comprised of practice-based education with up to two additional contacts to increase the importance of screening to GP staff and their confidence to offer tests through skill development (including videos). Practical resources (targets, posters, invitation cards, computer reminders, newsletters including feedback) aimed to actively influence social cognitions of staff, increasing their testing intention. Results Data from 76 intervention and 81 control practices were analysed. In intervention practices, chlamydia screening test rates were 2.43/100 15-24-year-olds registered preintervention, 4.34 during intervention and 3.46 postintervention; controls testing rates were 2.61/100 registered patients prior intervention, 3.0 during intervention and 2.82 postintervention. During the intervention period, testing in intervention practices was 1.76 times as great (CI 1.24 to 2.48) as controls; this persisted for 9 months postintervention (1.57 times as great, CI 1.27 to 2.30). Chlamydia infections detected increased in intervention practices from 2.1/1000 registered 15-24-year-olds prior intervention to 2.5 during the intervention compared with 2.0 and 2.3/1000 in controls (Estimated Rate Ratio intervention versus controls 1.4 (CI 1.01 to 1.93). Conclusions This complex intervention doubled chlamydia screening tests in fully engaged practices. The modified Zelen design gave realistic measures of practice full engagement (63%) and efficacy of this educational intervention in general practice; it should be used more often.
    Sexually transmitted infections 09/2013; 90(3). DOI:10.1136/sextrans-2013-051029 · 3.08 Impact Factor
  • Sexually Transmitted Infections 07/2013; 89(Suppl 1):A194-A194. DOI:10.1136/sextrans-2013-051184.0608 · 3.08 Impact Factor
  • The Lancet 04/2013; 381(9875):1358-9. DOI:10.1016/S0140-6736(13)60882-X · 45.22 Impact Factor
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    ABSTRACT: SUMMARY In August 2011, we investigated an outbreak of Escherichia coli O157 in Plymouth, England, utilizing a case-control study and food traceback. Nine cases, eight laboratory-confirmed with E. coli O157 phage type 21/28 verocytotoxin 2 and one epidemiologically linked, had onsets from 30 July 2011 to 15 August 2011. We compared cases (n = 8) with controls (n = 28) of similar age and sex (median age 61 vs. 55 years, females 75% vs. 61%). Cases were 58 times more likely to have eaten crab (88% vs. 11%; odds ratio 58, 95% confidence interval 4-2700). Eight cases consumed crab sourced from the same supplier who was not registered with the local authority. This outbreak pointed to crab as a possible vehicle of E. coli O157 infection. We ensured the withdrawal of crab meat sourced from unregistered suppliers from food venues by 25 August 2011. We also emphasized the importance of only using registered suppliers to the food venues. Since then no further associated cases have been reported.
    Epidemiology and Infection 12/2012; 141(10):1-8. DOI:10.1017/S0950268812002816 · 2.49 Impact Factor
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    Alma Tostmann, Teun Bousema, Isabel Oliver
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    ABSTRACT: Outbreaks in which most or all persons were exposed to the same suspected source of infection, so-called universal exposure, are common. They represent a challenge for public health specialists because conducting analytical studies in such investigations is complicated by the absence of a nonexposed group. We describe different strategies that can support investigations of outbreaks with universal exposure. The value of descriptive epidemiology, extensive environmental investigation, and the hypothesis-generation phase cannot be overemphasized. An exposure that seems universal may in fact not be universal when additional aspects of the exposure are taken into account. Each exposure has unique characteristics that may not be captured when investigators rely on the tools readily at hand, such as standard questionnaires. We therefore encourage field epidemiologists to be creative and consider the use of alternative data sources or original techniques in their investigations of outbreaks with universal exposure.
    Emerging Infectious Diseases 11/2012; 18(11):1717-22. DOI:10.3201/eid1811.111804 · 7.33 Impact Factor
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    ABSTRACT: In February 2012, we investigated a cluster of people who presented at a local emergency department with sudden onset of vomiting after mistaken consumption of daffodils. We interviewed patients to collect information on daffodil purchase and consumption. With Local Authority we investigated points of sale to understand the source of confusion. We identified 11 patients (median age: 23 years, range 5-60 years, eight females) among Bristol (UK) residents of Chinese origin. The most commonly reported symptoms were vomiting (n = 11) and nausea (n = 9) that developed within 12 h of daffodil consumption. There were no hospitalisations or deaths. Patients were clustered in two family dinners and one party. Bunches of pre-bloom daffodil stalks were purchased in two stores of one supermarket chain, which displayed daffodils next to vegetables, not marked as non-edible. Patients cooked and consumed daffodils mistaking them for Chinese chives/onions. Gastro-intestinal poisoning should be considered in differential diagnoses of gastroenteritis. Multi-cultural societies are at risk of confusion between non-edible and edible plants. Supermarket presentation of daffodils may have contributed to mistaken consumption. We recommended explicit labelling and positioning of daffodils, away from produce. The supermarket chain introduced graphic 'non-edible' labels. No further patients were reported following action.
    Clinical Toxicology 08/2012; 50(8):788-90. DOI:10.3109/15563650.2012.718350 · 3.12 Impact Factor
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    ABSTRACT: BACKGROUND: Uptake of the English National Chlamydia Screening Programme is lower than predicted necessary to result in a rapid fall in chlamydia prevalence. Peer-led approaches may increase screening uptake but their feasibility and acceptability to young people is not known. METHODS: Focus groups and interviews with young women and men. Following interview, chlamydia postal kits were introduced to participants and their opinions on giving these out to their peers sought. Participants were asked for their views and experiences of discussing chlamydia screening and distributing kits to their friends 4-8 weeks after the focus group/interview. All kits returned to the laboratory over a 9-month period were recorded. RESULTS: Six men (mean age 19 years) and six women (mean age 20 years) were recruited. In total 45 kits were distributed, 33 (73%) to female participants. 22 (67%) and 3 (25%) of kits given to females and males, respectively, were given to peers. Ten kits (22%; seven female, three male) all of which had been given out by females, were returned for testing. Participants generally felt positive about the idea of peer-led screening (PLS) using postal kits. However, embarrassment was a key theme, particularly among men. Generally women but not men were able to discuss PLS among their close friends. Both sexes felt PLS would be easier if kits were readily available in multiple sites, and chlamydia screening was more widely promoted. CONCLUSION: Female PLS but not male PLS was successful in recruiting peers to participate in chlamydia screening. An evaluation of the acceptability and cost-effectiveness of PLS is now indicated.
    Journal of Family Planning and Reproductive Health Care 08/2012; 39(1). DOI:10.1136/jfprhc-2011-100151 · 2.33 Impact Factor
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    ABSTRACT: 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: bulletin europeen sur les maladies transmissibles = European communicable disease bulletin 01/2012; 17(13). · 4.66 Impact Factor
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    ABSTRACT: Hospital outbreaks of group A streptococcal (GAS) infection can be devastating and occasionally result in the death of previously well patients. Approximately one in ten cases of severe GAS infection is healthcare-associated. This guidance, produced by a multidisciplinary working group, provides an evidence-based systematic approach to the investigation of single cases or outbreaks of healthcare-associated GAS infection in acute care or maternity settings. The guideline recommends that all cases of GAS infection potentially acquired in hospital or through contact with healthcare or maternity services should be investigated. Healthcare workers, the environment, and other patients are possible sources of transmission. Screening of epidemiologically linked healthcare workers should be considered for healthcare-associated cases of GAS infection where no alternative source is readily identified. Communal facilities, such as baths, bidets and showers, should be cleaned and decontaminated between all patients especially on delivery suites, post-natal wards and other high risk areas. Continuous surveillance is required to identify outbreaks which arise over long periods of time. GAS isolates from in-patients, peri-partum patients, neonates, and post-operative wounds should be saved for six months to facilitate outbreak investigation. These guidelines do not cover diagnosis and treatment of GAS infection which should be discussed with an infection specialist.
    The Journal of infection 11/2011; 64(1):1-18. DOI:10.1016/j.jinf.2011.11.001 · 4.02 Impact Factor
  • Sexually Transmitted Infections 07/2011; 87(Suppl 1):A207-A207. DOI:10.1136/sextrans-2011-050108.251 · 3.08 Impact Factor
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    ABSTRACT: The United Kingdom implemented a containment strategy for pandemic (H1N1) 2009 through administering antiviral agents (AVs) to patients and their close contacts. This observational household cohort study describes the effect of AVs on household transmission. We followed 285 confirmed primary cases in 259 households with 761 contacts. At 2 weeks, the confirmed secondary attack rate (SAR) was 8.1% (62/761) and significantly higher in persons <16 years of age than in those >50 years of age (18.9% vs. 1.2%, p<0.001). Early (<48 hours) treatment of primary case-patients reduced SAR (4.5% vs. 10.6%, p = 0.003). The SAR in child contacts was 33.3% (10/30) when the primary contact was a woman and 2.9% (1/34) when the primary contact was a man (p = 0.010). Of 53 confirmed secondary case-patients, 45 had not received AV prophylaxis. The effectiveness of AV prophylaxis in preventing infection was 92%.
    Emerging Infectious Diseases 06/2011; 17(6):990-9. DOI:10.3201/eid/1706.101161 · 7.33 Impact Factor
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    ABSTRACT: The UK was one of few European countries to document a substantial wave of pandemic (H1N1) 2009 influenza in summer 2009. The First Few Hundred (FF100) project ran from April-June 2009 gathering information on early laboratory-confirmed cases across the UK. In total, 392 confirmed cases were followed up. Children were predominantly affected (median age 15 years, IQR 10-27). Symptoms were mild and similar to seasonal influenza, with the exception of diarrhoea, which was reported by 27%. Eleven per cent of all cases had an underlying medical condition, similar to the general population. The majority (92%) were treated with antiviral drugs with 12% reporting adverse effects, mainly nausea and other gastrointestinal complaints. Duration of illness was significantly shorter when antivirals were given within 48 h of onset (median 5 vs. 9 days, P=0.01). No patients died, although 14 were hospitalized, of whom three required mechanical ventilation. The FF100 identified key clinical and epidemiological characteristics of infection with this novel virus in near real-time.
    Epidemiology and Infection 11/2010; 138(11):1531-41. DOI:10.1017/S0950268810001366 · 2.49 Impact Factor
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    ABSTRACT: The UK was one of few European countries to document a substantial wave of pandemic (H1N1) 2009 influenza in summer 2009. The First Few Hundred (FF100) project ran from April–June 2009 gathering information on early laboratory-confirmed cases across the UK. In total, 392 confirmed cases were followed up. Children were predominantly affected (median age 15 years, IQR 10–27). Symptoms were mild and similar to seasonal influenza, with the exception of diarrhoea, which was reported by 27%. Eleven per cent of all cases had an underlying medical condition, similar to the general population. The majority (92%) were treated with antiviral drugs with 12% reporting adverse effects, mainly nausea and other gastrointestinal complaints. Duration of illness was significantly shorter when antivirals were given within 48 h of onset (median 5 vs. 9 days, P=0·01). No patients died, although 14 were hospitalized, of whom three required mechanical ventilation. The FF100 identified key clinical and epidemiological characteristics of infection with this novel virus in near real-time.
    Epidemiology and Infection 10/2010; 138(11):1531 - 1541. · 2.49 Impact Factor
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    ABSTRACT: A source of infection is rarely identified for sporadic cases of Legionnaires' disease. We found that professional drivers are five times more commonly represented among community acquired sporadic cases in England and Wales than expected. We therefore investigated possible risk exposures in relation to driving or spending time in a motor vehicle. A case control study including all surviving community acquired sporadic cases in England and Wales with onset between 12 July 2008 and 9 March 2009 was carried out. Cases were contacted by phone and controls were consecutively recruited by sequential digital dialling matched by area code, sex and age group. Those who consented were sent a questionnaire asking questions on driving habits, potential sources in vehicles and known risk factors. The results were analysed using logistic regression. 75 cases and 67 controls were included in the study. Multivariable analysis identified two exposures linked to vehicle use associated with an increased risk of Legionnaires' disease: Driving through industrial areas (OR 7.2, 95%CI 1.5-33.7) and driving or being a passenger in a vehicle with windscreen wiper fluid not containing added screenwash (OR 47.2, 95%CI 3.7-603.6). Not adding screenwash to windscreen wiper fluid is a previously unidentified risk factor and appears to be strongly associated with community acquired sporadic cases of Legionnaires' disease. We estimated that around 20% of community acquired sporadic cases could be attributed to this exposure. A simple recommendation to use screenwash may mitigate transmission of Legionella bacteria to drivers and passengers.
    European Journal of Epidemiology 09/2010; 25(9):661-5. DOI:10.1007/s10654-010-9471-3 · 5.15 Impact Factor

Publication Stats

244 Citations
165.14 Total Impact Points

Institutions

  • 2012–2014
    • University of Bristol
      • School of Social and Community Medicine
      Bristol, England, United Kingdom
  • 2010–2013
    • Gloucestershire Hospitals NHS Foundation Trust
      Gloucester, England, United Kingdom
  • 2007–2013
    • Public Health England
      • South West (South) Health Protection Unit
      Londinium, England, United Kingdom
  • 2009
    • European Centre for Disease Prevention and Control
      Solna, Stockholm, Sweden