Module 3 Evaluation unit

Report
Global Programme to Eliminate Lymphatic Filariasis (GPELF)
Training in monitoring and epidemiological assessment of mass
drug administration for eliminating lymphatic filariasis
TAS
Module 3 Evaluation unit
Module 3 Evaluation unit
Learning objectives
By the end of this module, you should understand:
 How to define a survey area, known as an
evaluation unit (EU).
Slide 2
Module 3 Evaluation unit
Overview

Survey area for a TAS

Defining an EU
 Combining IUs
 Dividing IU
 Geographical area of an EU
Slide 3
Module 3 Evaluation unit
Survey area for a TAS
 If all the data from relevant IUs confirm that they are
eligible for a TAS, planning can begin.
 The first step in designing a TAS is to define the survey
area.
Evaluation unit
1. Survey area
2. Survey site
3. Sampling strategy
School
Cluster-based sampling
4. Sample size
Slide 4
Module 3 Evaluation unit
Community
Systematic sampling
Sample size and critical cut-off
Census
Survey area for a TAS
 Implementation unit (IU): The administrative unit in a
country used for MDA
 Evaluation unit (EU): An area selected for a TAS
Slide 5
Module 3 Evaluation unit
Defining an EU
IUs within an EU can be combined, divided or remain the
same, but all IUs in a country in which MDA is conducted
must be included in a TAS.
 IUs in an EU are usually contiguous.
 All IUs in an EU should have had at least five effective rounds of
MDA (i.e. ≥ 65% total population) and meet all the eligibility
criteria for conducting a TAS.
 All areas in the EU should have similar epidemiological features and
LF transmission dynamics (e.g. epidemiological drug coverage,
baseline prevalence, prevalence of Mf or Ag in sentinel and spotcheck sites, principal parasites, vector abundance).
 The population should not exceed 2 million.
Slide 6
Module 3 Evaluation unit
Combining IUs
Unit
Total
population
Baseline Mf
prevalence (%)
MDA coverage (%)
#1
#2
#3
#4
#5
Sentinel site Mf
prevalence (%)
(after fifth round)
Spot-check site
Mf prevalence
(%)
1
32 983
2.1
81
69
79
76
76
0
0
2
101 438
3.4
78
67
77
72
76
0.3
0.1
3
52 138
2.9
75
70
72
76
68
0.1
0.1
2
1
Endemic IU
3
Slide 7
Module 3 Evaluation unit
MDA
Dividing an IU
Total
population
2 647 953
Baseline Mf
prevalence (%)
2.8
MDA coverage (%)
#1
#2
#3
#4
#5
79
66
71
74
72
Sentinel site Mf
prevalence (%)
(after fifth round)
Spot-check site
Mf prevalence
(%)
0.2
0.3
Endemic IU
MDA
2
1
3
Slide 8
Module 3 Evaluation unit
Sub-district
Total population
Baseline Mf
prevalence (%)
1
798 234
1.8
2
989 436
5.4
3
860 283
1.2
Geographical area of an EU
 Although there is no upper limit to the geographical area
of an EU, the following considerations should be taken
into account when combining IUs:
 The probability that foci of infection will be missed
increases as the geographical area of the EU
increases.
 Covering a larger area during the survey may
increase logistical requirements (e.g. transport
costs).
Slide 9
Module 3 Evaluation unit
Exercise
Using existing data (e.g. maps, list of IUs, population sizes,
number of rounds of MDA and coverage).
1. Define an appropriate EU(s).
Note: Some of the data will have been reported on the
‘ELIGIBILITY’ worksheet of the TAS Eligibility and Reporting Form
2. Present the defined EU(s) to the group.
Slide 10
Module 3 Evaluation unit

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