Plasmodium falciparum parasite infection prevalence from a household survey in Zambia using microscopy and a rapid diagnostic test: implications for monitoring and evaluation.

This paper presents estimates of P. falciparum infection prevalence in children under 5 years old in the context of a population-based household survey in Luangwa District (Lusaka Province), Zambia, an area where greater than 75% of households possess at least one insecticide-treated mosquito net (ITN). The sensitivity and specificity of an HRP-2 rapid diagnostic test (RDT) (ICT Malaria Pf((R))) compared to microscopy, as well as factors associated with discordant diagnostic results are also presented. P. falciparum infection prevalence was estimated at 7.0% (95% CI 4.9-9.0%) using microscopy. Using microscopy as the gold standard, the sensitivity of the HRP-2 RDT was 100% and specificity was 91.5%; positive predictive value was estimated to be 46.7% (95% CI 36.3-57.4%). RDT discordance, or HRP-2 false positivity, was highest among older children, those in the northern part of Luangwa District, and those with a reported history of antimalarial treatment. These data suggest microscopy should remain the gold standard for estimating malaria parasite point prevalence from household surveys for monitoring and evaluation purposes.