Journal of Public Health Advance Access originally published online on June 28, 2007
Journal of Public Health 2007 29(3):292-297; doi:10.1093/pubmed/fdm042
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Survey of tuberculosis incidents in hospital healthcare workers, England and Wales, 2005
Charlotte Anderson, Scientist (Epidemiology)1
Ibrahim Abubakar, Consultant Epidemiologist1,
Helen Maguire, Regional Epidemiologist2
Pam Sonnenberg, Senior Lecturer in Epidemiology1,3
1 Respiratory Diseases Department, Centre for Infections, Health Protection Agency, Colindale, NW9 5EQ, UK
2 London Regional Epidemiology, Health Protection Agency, Holborn, London, UK
3 Centre for Sexual Health and HIV Research, University College London, London, UK
Address correspondence to Ibrahim Abubakar, E-mail: ibrahim.abubakar{at}hpa.org.uk
Background Tuberculosis (TB) incidence has increased in England and Wales since 1987, with much of the increase in migrants from high TB incidence countries. The National Health Service increasingly depends on healthcare workers (HCWs) trained abroad, often from areas of high TB incidence. A retrospective survey of TB incidents in hospital-based HCWs was carried out to describe their frequency, distribution and characteristics.
Methods Reports of HCWs with TB in hospitals were identified among routine surveillance of TB incidents. Additional data on these and reports of further incidents fitting the study definition were obtained by contacting local and regional Health Protection Units.
Results At least 105 incidents of TB in hospital-based HCWs occurred in England and Wales in 2005. Most involved HCWs from high incidence countries, and most cases had pre-employment occupational health screening. We found no evidence of onward transmission within hospitals.
Conclusions Pre-employment screening for active disease may not be enough to prevent the occurrence of these incidents. A high index of suspicion among HCWs with TB symptoms is needed. Detection of latent infection with interferon gamma release assays, and the use of preventive treatment, should be evaluated.
Keywords: tuberculosis, healthcare workers, hospitals
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Introduction |
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Tuberculosis (TB) has increased annually in England and Wales since 1987, with much of the rise in migrants from high TB incidence countries.1 Within the UK National Health Service (NHS), there is an increasing dependency on foreign-trained healthcare workers (HCWs). Eight percent of all UK-registered nurses in 2003 qualified overseas (although this varied by region with one in four London nurses foreign trained).2 The proportion of newly registered nurses from overseas is much higher, with 43% in 2003 qualifying outside the UK. Among doctors, the proportion is even higher: 63% of those newly registered in 2004 trained overseas.3 In particular, those from non-European Economic Area countries increased from 33% in 1994 to 44% by 2002.4
The main countries from where non-UK-born HCWs originate are the Philippines, South Africa, Australia, India, Zimbabwe and a number of other African countries.4 With the exception of Australia, these countries have high TB rates (with an annual incidence of >168/100 000 in 2004).5 HCWs have also been shown to have a higher prevalence of latent TB infection, and higher incidence of TB disease, than the general population in low- and middle-income countries.6
The Health Protection Agency Enhanced TB Surveillance (ETS) collects clinical and demographic information on TB patients in England and Wales. HCWs can be identified among cases if information on occupation is completed. In 2005, 399 (5%) of the 8037 ETS cases were known to be HCWs, making up 8% (399/4980) of cases with occupation reported (Table 1). When compared with all TB cases, HCWs were more likely to be non-UK born (89 versus 73%) and female (67 versus 45%).
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Incidents involving potential TB transmission from HCWs are frequently reported to the Health Protection Agency for information or advice. In response to increased reporting of incidents in a range of institutional settings, and a lack of evidence to inform their public health management, a passive system of TB incident and outbreak surveillance (TBIOS) was established in 2004.
Information in TBIOS is often limited, particularly concerning actions taken and their outcomes; and completeness of reporting was unknown. In view of this, and a sense of increased complexity of incidents for which advice was sought, a retrospective survey of TB-related incidents in hospital-based HCWs in England and Wales was carried out for 2005. The aim was to describe the frequency, distribution and characteristics of these incidents and evaluate the completeness of the current surveillance system.
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Methods |
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TOPIntroductionMethodsResultsDiscussionLimitations of this studyAppendixAcknowledgementsReferences |
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Reports of hospital HCWs with TB were identified among routine surveillance (TBIOS). Letters were sent to local and regional contacts, asking them to provide additional data on these incidents using a structured questionnaire (Appendix 1), and to provide complete information on any other incidents fitting the agreed definition. For the purposes of this survey, a TB incident was where potential transmission of TB was identified, resulting in public health action, HCWs were any persons working in a healthcare setting (with patients or clinical specimens) and a hospital was any secondary or tertiary centre providing in-patient care, excluding nursing homes.
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Results |
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In 2005, TBIOS contained 161 incidents in healthcare settings. Of these, 103 involved HCWs with TB, and in 63 cases, the HCWs were working in a hospital (an increase from 52 such reports in 2004). Questionnaires on 82 incidents were returned during the survey, more than half representing incidents not already known in TBIOS. The minimum number occurring in England and Wales in 2005 is therefore 105 (23 TBIOS alone, 42 survey alone and 40 from both, Table 2).
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Among the 82 incidents identified through the survey, the index HCWs were born outside of the UK in 88% (72) of cases, with most born in India or Sub-Saharan Africa (Fig. 1). Seventy-nine percent (44/56 where year of entry was known) were diagnosed with TB more than 2 years after entering the UK. Where known, 79% (34/43) of HCWs underwent pre-employment occupational health screening: almost all carried out by occupational health professionals (five by self-assessment).
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More than half of the HCWs were employed as nurses (51%, 33/63) and 38% (24/63) were doctors (Fig. 2). Thirty-five percent (29) of HCWs in the survey had sputum smear-positive disease. Of the 51 known culture-confirmed cases, two (4%) were multidrug resistant (MDR). The proportion of all culture confirmed cases in England and Wales with MDR-TB has remained around 1% in recent years.1
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Workplace contacts were known to be screened in 29% of incidents (24/82). Methods and extent of contact investigation varied according to infectiousness of the HCWs, exposure to patients and staff and susceptibility of exposed contacts. Where specified, 76% (13/17) of screening exercises involved chest X-ray and 76% (13/17) tuberculin skin testing. Both were done in 53% of events (9/17). No use of interferon gamma release assays was reported. In a number of incidents, screening was not carried out actively, but letters of information and advice were sent to contacts.
No cases of active disease were identified in any hospital patient or staff contact. There were also no cases of latent TB infection identified in workplace contacts, although this was not always tested for.
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Discussion |
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TOPIntroductionMethodsResultsDiscussionLimitations of this studyAppendixAcknowledgementsReferences |
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Main finding of this study
This study found at least 105 incidents involving potential TB transmission from HCWs in hospital settings to have occurred in England and Wales in 2005. The incidents mainly included foreign-born doctors and nurses as the index case. The results of this study suggest that these individuals developed TB even with occupational screening at employment. Despite a number of large-scale screening exercises following the identification of potentially infectious HCWs no further cases were identified.
What is already known on this topic
The occurrence of infectious TB in HCWs is a frequent cause of considerable anxiety and public health action in hospitals in most low TB incidence countries. There has been a recent rise in the number of such events in HCWs, and also in the recruitment of HCWs from high TB burden countries in England and Wales.
What this study adds
This survey demonstrated that the true occurrence of incidents involving potential TB transmission from HCWs in hospitals is likely to be more than 100 per year, higher than the number reported to the current surveillance system, TBIOS, which had information on 60% of the total.
Regional numbers of incident reports did not always correlate with TB incidence in that area, suggesting that HCWs who develop disease do so following infection in the past or abroad. Also, regions which deal with many incidents may have low TB rates, and therefore not have the expertise or resources to manage potential outbreaks.
Unlike in low- and middle-income countries with high rates of TB among the general population,6 most HCWs in this high-income, relatively low incidence setting were likely to have been infected in their country of origin, rather than through occupational exposure in the UK.
The NHS employs more than three times as many nurses as doctors.7 The proportion of incidents where the HCW was a doctor compared with a nurse was therefore higher than expected (24 doctors versus 33 nurses, a ratio of 1 : 1.4). This may be because doctors are at higher risk, or because incidents involving doctors were more likely to be reported: this possibility is supported by the fact that the proportion of doctors with sputum smear-positive disease was only 17% (4/24), whereas more than half (55%, 18/33) of the nurses had positive sputum smears.
The Chief Medical Officer's Tuberculosis Action Plan for England8 calls for comprehensive occupational screening of all new UK HCWs. Guidelines from the National Institute for Health and Clinical Excellence9 recommend new employees working with patients or clinical specimens complete a TB screen before starting.
This survey suggests pre-employment screening for active disease will not be enough to prevent incidents in healthcare settings involving HCWs with TB. A low threshold of suspicion coupled with early assessment of any HCWs with suggestive symptoms is needed. Furthermore, the effectiveness and cost-effectiveness of pre-employment screening for latent infection, including the use of interferon gamma release assays, and the systems necessary to ensure completion of a course of preventive treatment, should be evaluated.
Identification and management of outbreaks would be facilitated by linking surveillance of incidents to laboratory and clinical case reports. In addition, the implementation of a national strain typing strategy will provide opportunities to identify the occurrence of transmission incidents. Lessons learned by this process will support the management of future incidents.
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Limitations of this study |
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TOPIntroductionMethodsResultsDiscussionLimitations of this studyAppendixAcknowledgementsReferences |
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The main limitation of this survey, which gives the first national estimates on such incidents, was that is was not complete, with some regions (in whole or part) under-reporting. Because of the retrospective nature of the survey, comparison between areas was complicated by variation in the quality of information available from each incident. Furthermore, the definitions used and actions taken for each incident differed.
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Appendix |
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TOPIntroductionMethodsResultsDiscussionLimitations of this studyAppendixAcknowledgementsReferences |
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(1) Questionnaire
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Acknowledgements |
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TOPIntroductionMethodsResultsDiscussionLimitations of this studyAppendixAcknowledgementsReferences |
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We are very grateful to all those who contributed to the survey, and all who regularly contribute to TB surveillance, in particular Health Protection Units around the country. Regional TB Leads: Sue Appleby, Ruth Gelletlie, Mike Lilley, John Magee, Helen Maguire, Philip Monk, Marko Petrovic, Grace Smith, Corry Van Den Bosch. Local/regional NHS and HPA staff including Muhammad Abid, Sudy Anaraki, Caroline Black, Tricia Brown, Kalsang Childs, Evdokia Dardamissis, Janet Fee, Mike Gent, Kim Gunn, Paul Hatton, Sandra Johnson, Diana McInnes, Rosemary McNaught, Sally Millership, Lika Nehaul, Jane Parry, Sam Perkins, Nick Phin, Pam Rush, Graham Sutton, Sue Thompson and Alan Tweddell. We wish to thank Alistair Story, Esther Kissling, Isabelle Giraudon, Su Brailsford and Ruth Ruggles for comments on the design of the survey.
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Footnotes |
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This survey was carried out with national surveillance data. The Health Protection Agency has Patient Information Advisory Group approval to hold and analyse national surveillance data for public health purposes under Section 60 of the UK Health and Social Care Act 2001. Specific ethical approval was therefore not required. 
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References |
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TOPIntroductionMethodsResultsDiscussionLimitations of this studyAppendixAcknowledgementsReferences |
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- Focus on tuberculosis: annual surveillance report 2006 – England, Wales and Northern Ireland. Health Protection Agency. http://www.hpa.org.uk/publications/PublicationDisplay.asp?PublicationID=62 (November 2006).
- Aiken LH, Buchan J, Sochalski J, Nichols B, Powell M. Trends in international nurse migration. Health Aff (2004) 23(3):69–77.
[Abstract/Free Full Text] - General Medical Council Annual Report 2004/05. http://www.gmc-uk.org/publications/annual_reports/index.asp.
- Bach S. International migration of health workers: labour and social issues. In: International Labour Office Working Paper No. 209 (2003) Geneva: International Labour Office.
- WHO. Global tuberculosis control: surveillance, planning, financing. In: WHO Report 2006 (2007) Geneva: WHO/HTM/TB/2006.362. www.who.int/tb/publications/global_report/.
- Joshi R, Reingold AL, Menzies D, Pai M. Tuberculosis among health-care workers in low- and middle-income countries: a systematic review. Public Libr Sci Med (2006) 3(12):2376–2391.
- The Information Centre: Staff in the NHS 2006. (2007) http://www.ic.nhs.uk/statistics-and-data-collections/workforce/nhs-staff-numbers/nhs-staff-1996-2006.
- Stopping tuberculosis in England – an action plan from the Chief Medical Officer. Gateway reference: 1176. (2004) London: Department of Health. http://www.dh.gov.uk/PolicyAndGuidance/HealthAndSocialCareTopics/Tuberculosis/fs/en.
- National Institute for Health and Clinical Excellence – Tuberculosis. (2006) www.nice.org.uk/CG033.
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