Screening for latent tuberculosis in UK health care workers

Active tuberculosis (TB) infection was diagnosed in two health care workers (HCWs) originally from high-incidence countries at a National Health Service (NHS) hospital trust in Northern England. In response, the trust screened current clinical employees from countries with a high TB prevalence for active and latent TB infection (LTBI).

To identify the number of HCWs, within the organization, who are at risk of TB infection.

Clinical employees from countries with a high TB prevalence (those described by the World Health Organization as having an incidence of >40 cases per 100000 populations) were reviewed. Employees were identified via human resource systems and occupational health records, from which nationality or country of birth was identified. A letter was sent to identified employees advising of the rationale for a reviewed screening process and inviting them to attend for an interferon-gamma release assay (IGRA) blood test.

A total of 587 clinical staff were identified as fitting the criteria of clinical HCWs from high-incidence countries. Of 469 HCWs screened, 27% screened positive using IGRA. This represented 4% of the total clinical workforce for the organization.

A considerable proportion of the workforce at this NHS hospital trust had previously undiagnosed LTBI, carrying a risk of conversion to active disease. Further action, such as treatment of LTBI or increased workforce awareness of symptoms of active disease, could help to reduce the risk of transmission of TB to patients and the need for associated 'look-back' exercises.