Validation process for the elimination of trachoma
Elimination of trachoma as a public health problem is defined as:
A prevalence of trachomatous trichiasis (TT) “unknown to the health system” of <0.2% in adults aged 15 years and above.
A prevalence of trachomatous inflammation-follicular (TF) in children aged 1–9 years of <5%, in each formerly endemic district.
In general, an Evaluation Unit (EU) is a district which, for trachoma elimination purposes, the World Health Organization defines as “the normal administrative unit for health care management, consisting of a population unit between 100,000– 250,000 persons.”
TT “unknown to the system” excludes trichiasis in individuals with post-surgical recurrence, people who have refused surgery, and those who are listed for surgery, and have had a surgical date set, but have not yet received an operation.
Data is used to guide the national trachoma elimination task force as it oversees the implementation of the SAFE strategy:
- S - trichiasis surgery
- A - antibiotic distribution, provided through Mass Drug Administration (MDA)
- F - facial cleanliness
- E - environmental improvement
Key decision stages for the national task force
- Baseline survey
- Impact survey
- Surveillance survey
1. Baseline survey
Based on the baseline findings a decision is taken on whether SAFE interventions are required or not.
- S is provided in an active manner if TT >0.2% in adults aged 15 years and above.
- A, F, E are provided if TF ≥5% in children aged 1-9 years.
The number of rounds of MDA provided depends on the prevalence of TF:
- TF ≥30%: 5 rounds
- TF 10-29.9%: 3 rounds
- TF 5-9.9%: 1 round
- TF <5%: A, F, E not required
2. Impact survey
This is carried out at EU level 6 to 12 months after the final planned MDA round.
- S continues to be provided in an active manner if TT >0.2% in adults aged 15 years and above.
- A, F, E are provided if TF ≥5% in children aged 1-9 years. As at baseline, the number of MDA rounds to be provided depends on the prevalence of TF.
3. Surveillance survey
The surveillance survey estimates TF prevalence at least 24 months after the last impact survey has shown a TF prevalence less than 5% in children aged 1-9 years at EU level.
- If TT <0.2% in adults aged 15 years and above - move to validation.
- If TF <5% in children aged 1-9 years old - move to validation.
Job aid: Key decision stages for the national task force (Download)
As you look at this guidance, consider why there may be variations in MDA cycles based on prevalence?
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