Background UK TB contact screening guidelines changed in 2016,¹ requiring screening only of contacts of patients with potentially transmissible disease, specifically pulmonary or laryngeal TB. TB contacts and the index case are likely to have had similar TB exposure, and it is possible that contacts who have not been directly infected by the index case will be missed using the new screening guidelines.

Aims and Objectives This study aimed to evaluate whether all cases of TB diagnosed through contact tracing in 2012 at a University Hospital would have been identified using the new screening guidelines.

Methods Case notes of all patients contact screened for TB aged 16 and over in 2012 were examined. Data were collected on the diagnosis of the patient screened (negative, latent, or active TB) and the site of TB of the index case.

Results Of the 445 screened, 394 (88.5%) were negative for TB, 44 (9.9%) had latent TB, and 7 (1.6%) had active TB. For 19.6% of those with latent or active TB diagnoses, the TB site in the index case was neither pulmonary nor laryngeal.

Conclusion By restricting contact screening of this 2012 cohort to those with pulmonary or laryngeal TB contact, 10 (19.6%) cases of TB would potentially have been missed. As these missed contacts and the TB index case may have had exposure to TB from the same, albeit unknown, person with a transmissible form of TB, the only way to identify these cases is with a broad screening approach. While the current guidelines are in place, this study highlights the importance of assessing the need for contact screening based on the individual clinical picture in each identified case of TB.

Reference

1. National Institute of Clinical Excellence. Tuberculosis Guidance: Update Information 2016.