Trachoma SAFE strategy — DTM&H MCQ
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Correct answer: C — Population-based trachoma grading survey
The correct answer is C, population-based trachoma grading survey. The clinical picture (follicular conjunctivitis in children and trichiasis in adults) is suggestive of trachoma, but the decision to deploy district-wide mass azithromycin under the SAFE strategy is never made from a single clinic impression. It requires a standardised, population-based prevalence survey using WHO simplified grading, measuring trachomatous inflammation, follicular (TF) in children aged 1 to 9 years and trachomatous trichiasis (TT) in adults, because treatment thresholds are defined at district level (TF greater than or equal to 5 percent triggers antibiotic mass drug administration, with more intensive rounds above 10 percent). Only a properly sampled survey gives an unbiased district prevalence estimate on which programmatic decisions and donor-funded azithromycin distribution can be justified. Why the other options are wrong: D. Skin snips for microfilariae: this diagnoses onchocerciasis, an entirely different filarial disease with skin and eye involvement, and has no role in trachoma prevalence assessment or SAFE strategy decisions. B. Widal test in school-aged children: this is a serological test for typhoid (Salmonella Typhi/Paratyphi) and is unrelated to conjunctival or eyelid disease. A. Blood culture from affected children: blood culture identifies bacteraemic illness such as typhoid or invasive bacterial infection, not chlamydial conjunctival disease, and trachoma diagnosis is clinical, not culture-based. E. Thick blood film during fever: this detects malaria parasitaemia and is irrelevant to eye disease burden or antibiotic mass drug administration decisions. Key point: district-level mass azithromycin under the SAFE strategy is triggered by a population-based TF and TT prevalence survey against WHO elimination thresholds, not by individual clinical cases.
Reference: WHO trachoma control, the SAFE strategy: TF prevalence in children aged 1-9 years and TT prevalence used to set district treatment thresholds (TF >=5% triggers mass antibiotic treatment, >=10% for repeated rounds); summarised in Xiao et al, Trachoma control: the SAFE strategy, PMC6288535, 2018, https://pmc.ncbi.nlm.nih.gov/articles/PMC6288535/