Module 2 Eligibility for a TAS TAS Global Programme to Eliminate Lymphatic Filariasis (GPELF) Training in monitoring and epidemiological assessment of mass drug administration for eliminating lymphatic filariasis Module 2 Eligibility for a TAS

Learning objectives By the end of this module, you should understand that the eligibility of an IU for a TAS is assessed on the basis of: 1.epidemiological drug coverage (programme coverage) 2.prevalence of infection at sentinel sites 3.prevalence of infection at spot-check sites Slide 2

Module 2 Eligibility for a TAS Overview  Eligibility criteria for a TAS  Epidemiological drug coverage (programme coverage)  Sentinel and spot-check surveys  Confirming eligibility Slide 3

Module 2 Eligibility for a TAS Eligibility criteria for a TAS Slide 4 In order for a national programme to start planning a TAS, the following criteria must be met in each IU:  At least five rounds of MDA were completed.  ≥ 65% epidemiological drug coverage achieved at each round.  Sentinel site: prevalence of Mf < 1% or prevalence of Ag < 2% after last effective round at all sites  Spot-check site: prevalence of Mf < 1% or prevalence of Ag < 2% after last effective round at all sites

Module 2 Eligibility for a TAS Epidemiological drug coverage  Epidemiological drug coverage (programme coverage) is defined as "the proportion of individuals in an IU who actually ingested the medicines" No. people reported to have ingested the medicines Total population in IU X 100 =  To reduce the prevalence of Mf in infected individuals to the threshold below which transmission is assumed to be no longer sustainable, at least 65% of the total population in each IU must ingest the medicines in at least five rounds of MDA. Slide 5

Module 2 Eligibility for a TAS Sentinel and spot-check surveys Slide 6  Blood surveys at sentinel sites are used to establish the baseline infection level and to monitor the impact of MDA on infection prevalence periodically.  Once a sentinel site is selected, it should continue to serve as the sentinel site throughout the programme.  Blood surveys at spot-check sites are used to confirm that the results of sentinel surveys represent the infection level in the entire IU.  At least one spot-check site is selected for each sentinel site.

Module 2 Eligibility for a TAS How many sentinel and spot-check sites are needed in each implementation unit? Slide 7  At least one sentinel site per 1 million people  At least one sentinel site in each IU; more sites may be selected when resources allow  Smaller IUs may be served by one sentinel site.  Combined IUs should be contiguous and have similar epidemiological characteristics.  Combined IUs should have conducted MDA at the same time.  The advice of WHO and the RPRG may be required.

Module 2 Eligibility for a TAS Characteristics of sentinel and spot-check sites Slide 8  The population should be at least 500 people (to collect samples from at least 300 people aged > 5 years)  Should be in an area of high transmission: high disease or parasite prevalence or vector abundance  or an area where difficulty in achieving high drug coverage is anticipated  No prior MDA for onchocerciasis  A stable population

Module 2 Eligibility for a TAS When should surveys be conducted? Slide 9  Baseline assessment: before first MDA  Mid-term evaluation: at least 6 months after third MDA (optional)  Follow-up survey: at least 6 months after fifth effective MDA Mapping TAS Mf and/or Ag prevalence (baseline) Mf and/or Ag prevalence (follow-up) Mf and/or Ag prevalence (optional) Round of MDA

Module 2 Eligibility for a TAS Slide 10  Target population  Convenience sample of at least 300 people  All members of the population in all age groups > 5 years (including pregnant women)  When the population is too large, a part can be chosen.  Diagnostic test  Blood film for prevalence of Mf  Immunochromatographic test (ICT) for Ag rate if resources allow (in W. bancrofti areas) When should surveys be conducted?

Module 2 Eligibility for a TAS Confirming eligibility to conduct a TAS Slide 11  Before assessing the eligibility of an IU, programme managers should compile all necessary records and complete the ‘INTRO’ and ‘ELIGIBILITY’ worksheets of the TAS Eligibility and Reporting Form.  The form helps in deciding whether the time is appropriate to conduct a TAS.  The form should be reviewed by the RPRG before the survey is planned.