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prevalence is an MDG indicator that can be directly measured in HBCs  Estimation of TB burden using tuberculin surveys no longer applicable in most settings  Funding is available for surveys, and governments and international agencies recognize importance of measuring impact Background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 6–10 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