N McCreesh1, A D Grant2, T A Yates3, A S Karat4, R G White1. 1. Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London. 2. TB Centre, London School of Hygiene & Tropical Medicine, London, UK, Africa Health Research Institute, School of Nursing and Public Health, University of KwaZulu-Natal, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa. 3. Section of Infectious Diseases and Immunity, Imperial College London, London, Institute for Global Health, University College London, London, UK. 4. TB Centre, London School of Hygiene & Tropical Medicine, London, UK.
Abstract
BACKGROUND: In South Africa, it is generally estimated that only 0.5-0.6% of people's contacts occur in clinics. Both people with infectious tuberculosis and people with increased susceptibility to disease progression may spend more time in clinics, however, increasing the importance of clinic-based transmission to overall disease incidence. METHODS: We developed an illustrative mathematical model of Mycobacterium tuberculosis transmission in clinics and other settings. We assumed that 1% of contact time occurs in clinics. We varied the ratio of clinic contact time of human immunodeficiency virus (HIV) positive people compared to HIV-negative people, and of people with infectious TB compared to people without TB, while keeping the overall proportion of contact time occurring in clinics, and each person's total contact time, constant. RESULTS: With clinic contact rates respectively 10 and 5 times higher in HIV-positive people and people with TB, 10.7% (plausible range 8.5-13.4%) of TB resulted from transmission in clinics. With contact rates in HIV-positive people and people with TB respectively 5 and 2 times higher, 5.3% (plausible range 4.3-6.3%) of all TB was due to transmission in clinics. CONCLUSION: The small amount of contact time that generally occurs in clinics may greatly underestimate their contribution to TB disease in high TB-HIV burden settings.
BACKGROUND: In South Africa, it is generally estimated that only 0.5-0.6% of people's contacts occur in clinics. Both people with infectious tuberculosis and people with increased susceptibility to disease progression may spend more time in clinics, however, increasing the importance of clinic-based transmission to overall disease incidence. METHODS: We developed an illustrative mathematical model of Mycobacterium tuberculosis transmission in clinics and other settings. We assumed that 1% of contact time occurs in clinics. We varied the ratio of clinic contact time of human immunodeficiency virus (HIV) positive people compared to HIV-negative people, and of people with infectious TB compared to people without TB, while keeping the overall proportion of contact time occurring in clinics, and each person's total contact time, constant. RESULTS: With clinic contact rates respectively 10 and 5 times higher in HIV-positive people and people with TB, 10.7% (plausible range 8.5-13.4%) of TB resulted from transmission in clinics. With contact rates in HIV-positive people and people with TB respectively 5 and 2 times higher, 5.3% (plausible range 4.3-6.3%) of all TB was due to transmission in clinics. CONCLUSION: The small amount of contact time that generally occurs in clinics may greatly underestimate their contribution to TB disease in high TB-HIV burden settings.
Authors: Nicky McCreesh; Aaron S Karat; Indira Govender; Kathy Baisley; Karin Diaconu; Tom A Yates; Rein Mgj Houben; Karina Kielmann; Alison D Grant; Richard White Journal: BMJ Glob Health Date: 2022-04
Authors: Nicky McCreesh; Aaron S Karat; Kathy Baisley; Karin Diaconu; Fiammetta Bozzani; Indira Govender; Peter Beckwith; Tom A Yates; Arminder K Deol; Rein M G J Houben; Karina Kielmann; Richard G White; Alison D Grant Journal: BMJ Glob Health Date: 2021-10
Authors: Fiammetta M Bozzani; Karin Diaconu; Gabriela B Gomez; Aaron S Karat; Karina Kielmann; Alison D Grant; Anna Vassall Journal: Health Policy Plan Date: 2022-03-04 Impact factor: 3.344