Lymphatic filariasis

Transmission Assessment Survey (TAS)

Monitoring and Epidemiological Evaluation

Mass drug administration (MDA) is needed to reduce infection in the community to levels below a threshold at which mosquitoes are unable to continue spreading the parasites from person to person and new infections are prevented. WHO recommends the transmission assessment survey (TAS) to determine when infections have been reduced below these target thresholds and MDA can stop. Once MDA has stopped, TAS is used as a surveillance tool to determine that infection levels are sustained below target thresholds.


  • Lymphatic filariasis: monitoring and epidemiological assessment of mass drug administration
    This manual is designed to ensure that national elimination programmes have available the best information on methodologies and procedures for (i) monitoring MDA, (ii) appropriately assessing when infection has been reduced to levels where transmission is likely no longer sustainable, (iii) implementing adequate surveillance after MDA has ceased to determine whether recrudescence has occurred, and (iv) preparing for verification of the absence of transmission.


Training in monitoring and epidemiological assessment of mass drug administration for eliminating lymphatic filariasis


  • Facilitators' guide and Learners' guide
    This manual is designed to teach personnel of national programmes to eliminate lymphatic filariasis, including regional and district health personnel, the essential elements of monitoring and evaluating national programmes to eliminate lymphatic filariasis. The focus is on planning and implementing TAS as an input to decide whether to move from MDA to post-MDA surveillance.
    The manual includes training modules, slides and video tutorial on how to use the Alere Filariasis Test Strip (FTS). Available in English, French and Portuguese.

Training in monitoring and epidemiological assessment of mass drug administration for eliminating lymphatic filariasis (training modules)

Theory of transmission assessment surveys (TAS)
Practical aspects of transmission assessment surveys
WHO TAS Eligibility and Planning Form
Additional resources for facilitators