In vivo parasitological measures of artemisinin susceptibility
Kasia Stepniewska, Elizabeth Ashley, Sue J Lee, Nicholas Anstey, Karen I Barnes, Tran Quang Binh, Umberto D'Alessandro, Nicholas P J Day, Peter J de Vries, Grant Dorsey, Jean-Paul Guthmann, Mayfong Mayxay, Paul N Newton, Piero Olliaro, Lyda Osorio, Ric N Price, Mark Rowland, Frank Smithuis, Walter R J Taylor, François Nosten, Nicholas J White, Kasia Stepniewska, Elizabeth Ashley, Sue J Lee, Nicholas Anstey, Karen I Barnes, Tran Quang Binh, Umberto D'Alessandro, Nicholas P J Day, Peter J de Vries, Grant Dorsey, Jean-Paul Guthmann, Mayfong Mayxay, Paul N Newton, Piero Olliaro, Lyda Osorio, Ric N Price, Mark Rowland, Frank Smithuis, Walter R J Taylor, François Nosten, Nicholas J White
Abstract
Parasite clearance data from 18,699 patients with falciparum malaria treated with an artemisinin derivative in areas of low (n=14,539), moderate (n=2077), and high (n=2083) levels of malaria transmission across the world were analyzed to determine the factors that affect clearance rates and identify a simple in vivo screening measure for artemisinin resistance. The main factor affecting parasite clearance time was parasite density on admission. Clearance rates were faster in high-transmission settings and with more effective partner drugs in artemisinin-based combination treatments (ACTs). The result of the malaria blood smear on day 3 (72 h) was a good predictor of subsequent treatment failure and provides a simple screening measure for artemisinin resistance. Artemisinin resistance is highly unlikely if the proportion of patients with parasite densities of <100,000 parasites/microL given the currently recommended 3-day ACT who have a positive smear result on day 3 is <3%; that is, for n patients the observed number with a positive smear result on day 3 does not exceed (n + 60)/24.
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Source: PubMed