The role of prevalence surveys in measuring the burden of TB, progress in TB control and improving early case detection Ikushi Onozaki WHO/STB/TBS Global.

The role of prevalence surveys in measuring the burden of TB, progress in TB control and improving early case detection Ikushi Onozaki WHO/STB/TBS Global Task Force on TB Impact Measurement DEWG meeting, Oct , Geneva Background Task Force recommendations What is needed to implement a survey and what can surveys tell us? Current status of survey implementation Next steps Content TB prevalence is an MDG indicator that can be directly measured in HBCs Estimation of TB burden using tuberculin surveys no longer applicable in most settings Funding is available for surveys, and governments and international agencies recognize importance of measuring impact Background Task Force recommendations Countries where surveys are recommended 21 global focus countries 36 additional countries that met basic criteria How should surveys be implemented? Follow the guidelines! Recommended screening strategy Do smear and culture at least for with TB symptoms and/or abnormal chest X-ray What is needed to implement a survey? ( WHO headquarters, March 2008) Sample size : 30, ,000 Cluster size: 500-1,000 staff per field team for 610 months, 3-4 team operation Costs ~ US$1 million in Asia, US$2 million in Africa Capital investment (CXR, Lab, Cars), Human Resource (Salaries), Survey Operation (Field and Central), Pre & Post survey events, technical assistance What is required for a survey? Go to the community Survey day Transport people to X-ray site Individual interview by trained health professional from central unit TB related symptoms TB history Possible treatment Consultation Places Risk factors Develop and read images on the Spot Quality Direct X-ray is Available in Villages that contributed to high participation rates and 100% sputum collection from suspects Prevalence Survey in Viet Nam Digital technology was introduced for the first time to National Scale TB survey Smear Microscopy Direct Smear, ZN LED-FL Collect, Store, Transport and Put in Culture within 5 days Lab work What can be learned from a survey? A carefully designed survey can tell you lots more than TB prevalence Changes in TB burden and re-estimation of burden Performance of strategies for screening of TB suspects Health-seeking behaviour of TB patients and individuals reporting chest symptoms Where and why are cases missed by the NTP e.g. access to care, role of private sector Risk factors Prevalence of Sm+ TB in Cambodia, 2002, was half of previous estimate and previous study results Prevalence of S+ in Yangon, Myanmar, nearly 3 times previous national estimate -> National Survey Prevalence of S+ in Viet Nam, 2007, was 60% more than previous estimate Prevalence Surveys can help to revise and improve estimates of disease burden and CDR Re-estimation of TB Burden Strategies for screening TB suspects NTP Cambodia. National TB Prevalence Survey Report, , ** H Ayles et al. Plos one May e 5602, *** NTP Viet Nam. Presented in UNION APR Conference, Beijing, Sept % of confirmed cases in surveys do not have chronic cough Smear microscopy alone misses >50% of bacteriologically-confirmed TB *Africa 5 sub-national surveys average Where are cases being missed? 33 in NTP: around 130/100,000 = 260/100,000/year Yangon survey, 2006: 1/3 of TB patients being treated by GPs Current status of survey implementation Good progress in Asia No survey in Africa started yet urgent action required!! HBC Other countries preparing: Ghana, Malawi, Mali, Rwanda, Togo, Zambia, Next steps Workshop on prevalence surveys in 12 African countries, October 2009 Identification of bottlenecks holding up survey implementation Lessons from Asia How to solve the bottlenecks Role of Task Force partners in providing technical assistance to countries