LF MDA coverage targets — DTM&H MCQ

Correct answer: B — 65% of total population

The correct answer is B, 65% of total population. WHO's Global Programme to Eliminate Lymphatic Filariasis (GPELF) modelling established that mass drug administration (MDA) must achieve at least 65% epidemiological drug coverage, meaning actual ingestion of tablets calculated against the total population (not just the eligible population), sustained for a minimum of five consecutive annual rounds, in order to interrupt transmission of Wuchereria bancrofti and Brugia species. This threshold is the trigger used before proceeding to Transmission Assessment Surveys (TAS), which determine whether MDA can safely stop. The discriminating feature in the stem is "total population" as the denominator, which distinguishes this WHO epidemiological target from programmatic coverage figures that are often reported against the eligible population and therefore appear higher. Why the other options are wrong: C. 50% of total population: this coverage level is below the modelled threshold shown to interrupt transmission and would not achieve elimination even over multiple rounds. D. 80% of eligible population: this figure uses the wrong denominator (eligible rather than total population) and reflects a commonly cited but looser programmatic coverage measure, not the WHO epidemiological threshold that drives TAS decisions. A. 90% of children under 5: MDA targets the whole community at risk, not a specific age subgroup, since transmission depends on population-level microfilarial reservoir reduction, not paediatric coverage alone. E. 100% of microfilaraemia-positive individuals: MDA is a population-based, presumptive treatment strategy delivered without individual testing, so targeting only known microfilaraemic individuals would miss the asymptomatic reservoir sustaining transmission. Key point: WHO's 65% threshold refers to actual tablet ingestion measured against the total population (epidemiological coverage), sustained for at least five years, not coverage of eligible people alone.

Reference: World Health Organization / Global Programme to Eliminate Lymphatic Filariasis: 65% epidemiological drug coverage threshold for MDA, as described in Alexander ND, 'Are we nearly there yet? Coverage and compliance of mass drug administration for lymphatic filariasis elimination', Trans R Soc Trop Med Hyg 2015; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4321021/