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 <1 case per 1000 total population;
- A prevalence of trachomatous inflammation-follicular (TF) in children aged 1–9 years of <5%, in each formerly endemic district.
Districts are defined as the normal administrative unit for health care management, which for the purposes of clarification consist of a population unit between 100 000 and 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
- F - facial cleanliness
- E - environmental improvement
Key decision stages for the national task force
- Baseline using mapping
- Impact survey, and
- Surveillance survey
1. Baseline using mapping
Based on the baseline findings a decision is taken on whether SAFE interventions are required or not.
- S is provided if TT >1 per 1000 population
- A,F,E are provided if TF <5% in children 1-9 yrs old.
The number of MDA rounds 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 district level 6 months after the last MDA round.
S continues to be provided if TT >1 per 1000 population
A,F,E are provided if TF <5% in children 1-9 yrs old. As at baseline, the number of MDA rounds to be provided depends on the prevalence of TF
3. Surveillance survey
The surveillance survey estimates TT and TF 24 months after the last impact survey at the district level.
- If TT <1 per 1000 population – move to validation
- If TF <5% in children 1-9 yrs of age – move to validation
As you look at this guidance, consider why there may be variations in MDA cycles based on prevalence?
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