PfHRP2 and PfLDH antigen detection for monitoring the efficacy of artemisinin-based combination therapy (ACT) in the treatment of uncomplicated falciparum malaria

In Allada (Benin), 205 children aged 6-59 months with falciparum malaria received either artesunate-amodiaquine (ASAQ), artemether-lumefantrine (AL), or sulphadoxine-pyrimethamine (SP). Children included in the study were simultaneously followed by both RDT and high-quality microscopy for up to 42 days.At the time of inclusion, PfHRP2-based tests were positive in 203 children (99%) and PfLDH-based tests were positive in 204 (99.5%). During follow-up, independent of the treatment received, only 17.3% (28/162) of children effectively cured were negative with the PfHRP2 RDT at day 3, with a gradual increase in specificity until day 42. The specificity of antigen detection with the PfLDH test was 87% (141/162) on day 3, and between 92% and 100% on days 7 to 42. A statistical difference was observed between the persistence of PfHRP2 and PfLDH antigenaemia during follow-up in children treated with artemisinin-based combination therapy (ACT) but not with SP.Although both RDTs are as sensitive as microscopy in detecting true malaria cases, the PfHRP2 RDT had very low specificity during follow-up until day 28. On the other hand, the PfLDH test could be used to detect failures and, therefore, to assess anti-malarial efficacy.In response to increased anti-malarial drug resistance, artemisinin-based combination therapy (ACT) is recommended in Africa [1]. Due to the significantly higher cost of ACT than drugs formerly used, such as chloroquine and sulphadoxine-pyrimethamine (SP), strong emphasis has been placed on the importance of avoiding any unnecessary use of ACT, so as to minimize opportunities for the development of parasite drug resistance to it. Since clinical diagnosis is non-specific, laboratory confirmation is essential for accurate diagnosis of malaria. However, although microscopy is still considered the gold standard, it is unavailable in many endemic areas. An alternative is the use of a rapid diagnostic test (RDT) that is simple to perform, requires neither equip