Isabel Oliver

University of Bristol, Bristol, England, United Kingdom

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Publications (25)136.38 Total impact

  • [Show abstract] [Hide abstract]
    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;
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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. · 1.47 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. · 6.79 Impact Factor
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    ABSTRACT: To determine if a structured complex intervention increases opportunistic chlamydia screening testing of patients aged 15-24 years attending English general practitioner (GP) practices. 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. 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). 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. The trial was registered on the UK Clinical Research Network Study Portfolio database. UKCRN number 9722.
    Sexually transmitted infections 09/2013; · 2.18 Impact Factor
  • The Lancet 04/2013; 381(9875):1358-9. · 39.06 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; · 2.87 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. · 6.79 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. · 2.59 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; · 2.10 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.
    Euro surveillance: bulletin europeen sur les maladies transmissibles = European communicable disease bulletin 01/2012; 17(13). · 5.49 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. · 4.13 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. · 6.79 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. · 2.87 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. · 2.87 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. · 5.12 Impact Factor
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    ABSTRACT: Since the introduction of antibiotics, pneumococcal disease is predominantly sporadic, with occasional outbreaks. Our objective was to review the epidemiology of reported outbreaks of serious pneumococcal disease in closed settings to inform the development of guidelines to manage such outbreaks. We systematically reviewed the literature for reported outbreaks of serious pneumococcal disease in closed settings to inform the development of guidelines in managing such outbreaks. We identified 42 outbreaks reported in 39 papers---14 in hospitals, 12 in long term care facilities, five outbreaks in households, four in military settings, three in child care settings and two each in homeless shelters and jails. The serotype/group most frequently associated with outbreaks was 14 (seven outbreaks) followed by 4 (five outbreaks) then serotypes/groups 1, 9 and 9V each causing four outbreaks. The median outbreak size was four cases (2 - 46). The median duration was eight days, with 84% of cases occurring within 14 days of the first case. Outbreaks of serious pneumococcal disease are likely to continue happening requiring early recognition and implementation of public health measures in order to interrupt transmission. This study facilitated the development of the first UK interim guidelines for managing such outbreaks.
    The Journal of infection 04/2010; 61(1):21-7. · 4.13 Impact Factor
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    ABSTRACT: There is low uptake of chlamydia screening in general practices registered with the English National Chlamydia Screening Programme (NCSP). Aims. To explore staff's attitudes and behaviour around chlamydia screening and how screening could be optimized in general practice. A qualitative study with focus groups and interviews, in general practices in seven NCSP areas. Twenty-five focus groups and 12 interviews undertaken with a purposively selected diverse group of high and low chlamydia-screening practices in 2006-08. Data were collected and analysed using a framework analytical approach. Higher screening practices had more staff with greater belief in patient and population benefits of screening and, as screening was a subjective norm, it was part of every day practice. Many staff in the majority of other practices were uncomfortable raising chlamydia opportunistically and time pressures meant that any extra public health issues covered within a consultation were determined by Quality Outcomes Framework (QOF) targets. All practices would value more training and feedback about their screening rates and results. Practices suggested that use of computer prompts, simplified request forms and more accessible kits could increase screening. Practice staff need more evidence of the value of opportunistic chlamydia screening in men and women; staff development to reduce the barriers to broaching sexual health; simpler request forms and easily accessible kits to increase their ability to offer it within the time pressures of general practice. Increased awareness of chlamydia could be attained through practice meetings, computer templates and reminders, targets and incentives or QOF points with feedback.
    Family Practice 03/2010; 27(3):291-302. · 1.83 Impact Factor
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    ABSTRACT: We describe the investigation of an outbreak of Q fever in the town of Cheltenham, England. The outbreak was detected in June 2007, and prospective and retrospective case finding identified 30 confirmed or probable human cases. The investigation identified windborne spread of Coxiella burnetii from nearby sheep farms as the most likely source of infection. A telephone survey was conducted to identify risk practices at local farms. Subsequently the atmospheric dispersion model NAME was used to identify whether air from the identified farms with high risk practices had been carried into Cheltenham town centre during the risk period. Three high risk farms were identified and the modelling showed that air from all of these farms was carried over Cheltenham in the estimated risk period. The investigation resulted in an information campaign to farmers and production of improved advice for livestock farmers on reducing the risks of transmitting Q fever to humans.
    Euro surveillance: bulletin europeen sur les maladies transmissibles = European communicable disease bulletin 01/2010; 15(12). · 5.49 Impact Factor
  • Isabel Oliver, Deirdre Lewis
    Journal of Public Health 11/2009; 31(4):468-9. · 2.06 Impact Factor
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    ABSTRACT: General practice staff are reluctant to discuss sexual health opportunistically in all consultations. Health promotion materials may help alleviate this barrier. Chlamydia screening promotion posters and leaflets, produced by the English National Chlamydia Screening Programme (NCSP), have been available to general practices, through local chlamydia screening offices, since its launch. In this study we explored the attitudes of general practice staff to these screening promotional materials, how they used them, and explored other promotional strategies to encourage chlamydia screening. Twenty-five general practices with a range of screening rates, were purposively selected from six NCSP areas in England. In focus groups doctors, nurses, administrative staff and receptionists were encouraged to discuss candidly their experiences about their use and opinions of posters, leaflets and advertising to promote chlamydia screening. Researchers observed whether posters and leaflets were on display in reception and/or waiting areas. Data were collected and analysed concurrently using a stepwise framework analytical approach. Although two-thirds of screening practices reported that they displayed posters and leaflets, they were not prominently displayed in most practices. Only a minority of practices reported actively using screening promotional materials on an ongoing basis. Most staff in all practices were not following up the advertising in posters and leaflets by routinely offering opportunistic screening to their target population. Some staff in many practices thought posters and leaflets would cause offence or embarrassment to their patients. Distribution of chlamydia leaflets by receptionists was thought to be inappropriate by some practices, as they thought patients would be offended when being offered a leaflet in a public area. Practice staff suggested the development of pocket-sized leaflets. The NCSP should consider developing a range of more discrete but eye catching posters and small leaflets specifically to promote chlamydia screening in different scenarios within general practice; coordinators should audit their use. Practice staff need to discuss, with their screening co-ordinator, how different practice staff can promote chlamydia screening most effectively using the NCSP promotional materials, and change them regularly so that they do not loose their impact. Education to change all practice staff's attitudes towards sexual health is needed to reduce their worries about displaying the chlamydia materials, and how they may follow up the advertising up with a verbal offer of screening opportunistically to 15-24 year olds whenever they visit the practice.
    BMC Public Health 10/2009; 9:383. · 2.08 Impact Factor

Publication Stats

150 Citations
136.38 Total Impact Points

Institutions

  • 2014
    • University of Bristol
      Bristol, England, United Kingdom
  • 2010–2013
    • Gloucestershire Hospitals NHS Foundation Trust
      Gloucester, England, United Kingdom
  • 2009–2013
    • Public Health England
      • • Health Protection Agency - North East
      • • South West (South) Health Protection Unit
      Londinium, England, United Kingdom
    • European Centre for Disease Prevention and Control
      Solna, Stockholm, Sweden