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 epidemiological drug coverage ID: 752039
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Training in monitoring and epidemiological assessment of mass drug administration for eliminating lymphatic filariasis
Module 2 Eligibility for a TASSlide2
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:epidemiological drug coverage (programme coverage)prevalence of infection at sentinel sitesprevalence of infection at spot-check sites
Slide
2Slide3
Overview
Eligibility criteria for
a TAS
Epidemiological drug coverage (programme coverage)Sentinel and spot-check surveysConfirming eligibilitySlide
3Slide4
Eligibility criteria for a TAS
Slide
4In 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:
p
revalence
of
Mf
< 1% or prevalence of
Ag
< 2% after last effective
round at
all sitesSlide5
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.
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5Slide6
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.Slide7
How many sentinel and spot-check sites are needed in each implementation unit?
Slide
7
At least one sentinel site per 1 million peopleAt 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.Slide8
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 Slide9
When should surveys be conducted?
Slide
9
Baseline assessment: before first MDAMid-term evaluation: at least 6 months after third MDA (optional)
Follow-up survey: at least 6 months after fifth effective
MDA
Mapping
TAS
1
2
3
4
5
Mf and/or Ag prevalence (baseline)
Mf and/or Ag prevalence (follow-up)
Mf and/or Ag prevalence (optional)
Round of MDASlide10
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?Slide11
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.