TB Origins – Dr Alice Sawka: Where Does the 8-Hour Contact Tracing Rule Come From?

Dr Alice Sawka is joined by Dr Jack Callum, respiratory physician in London, and Dr Victoria Gray, infectious diseases physician in Brisbane, to explore the origins of the widely used “eight-hour rule” in TB contact tracing.Together, they examine the evidence behind this commonly used threshold, trace its roots to early studies of TB transmission during air travel, and discuss how clinicians and public health teams assess exposure risk. They also explore the practical challenges of contact tracing and the “stone in the pond” approach used to identify those at greatest risk of TB infection.This episode is the second in the TB Origins series, exploring the evidence and history behind long-standing TB clinical practices.Show NotesTuberculosis and air travel: guidelines for prevention and control – 3rd ed. “WHO/HTM/TB/2008.399” Available at: https://www.who.int/publications/i/item/9789241547505Driver CR, Valway SE, Morgan WM, Onorato IM, Castro KG. Transmission of Mycobacterium tuberculosis associated with air travel. JAMA. 1994 Oct 5;272(13):1031-5. PMID: 8089885.Kenyon TA et al. Transmission of multidrug-resistant Mycobacterium tuberculosis during a long airplane flight. N Engl J Med. 1996 Apr 11;334(15):933-8. doi: 10.1056/NEJM199604113341501. PMID: 8596593.Migliori GB, et al. Reducing tuberculosis transmission: a consensus document from the World Health Organization Regional Office for Europe. Eur Respir J. 2019 Jun 5;53(6):1900391. doi: 10.1183/13993003.00391-2019. PMID: 31023852.