fDeclining malaria transmission and known difficulties with current diagnostic tools for malaria, such as microscopy and rapid diagnostic tests (RDTs) in particular at low parasite densities, still warrant the search for sensitive diagnostic tests. Molecular tests need substantial simplification before implementation in clinical settings in countries where malaria is endemic. Direct blood PCR (db-PCR), circumventing DNA extraction, to detect Plasmodium was developed and adapted to be visualized by nucleic acid lateral flow immunoassay (NALFIA). The assay was evaluated in the laboratory against samples from confirmed Sudanese patients (n ‫؍‬ 51), returning travelers (n ‫؍‬ 214), samples from the Dutch Blood Bank (n ‫؍‬ 100), and in the field in Burkina Faso (n ‫؍‬ 283) and Thailand (n ‫؍‬ 381) on suspected malaria cases and compared to RDT and microscopy. The sensitivity and specificity of db-PCR-NALFIA compared to the initial diagnosis in the laboratory were 94.4% (95% confidence interval [CI] ‫؍‬ 0.909 to 0.969) and 97.4% (95% CI ‫؍‬ 0.909 to 0.969), respectively. In Burkina Faso, the sensitivity was 94.8% (95% CI ‫؍‬ 0.88.7 to 97.9%), and the specificity was 82.4% (95% CI ‫؍‬ 75.4 to 87.7%) compared to microscopy and 93.3% (95% CI ‫؍‬ 87.4 to 96.7%) and 91.4% (95% CI ‫؍‬ 85.2 to 95.3%) compared to RDT. In Thailand, the sensitivity and specificity were 93.4% (CI ‫؍‬ 86.4 to 97.1%) and 90.9 (95% CI ‫؍‬ 86.7 to 93.9%), respectively, compared to microscopy and 95.6% (95% CI ‫؍‬ 88.5 to 98.6%) and 87.1% (95% CI ‫؍‬ 82.5 to 90.6) compared to RDT. db-PCR-NALFIA is highly sensitive and specific for easy and rapid detection of Plasmodium parasites and can be easily used in countries where malaria is endemic. The inability of the device to discriminate Plasmodium species requires further investigation.

SUMMARYFunctional impairment of dendritic cells (DCs) is part of a survival strategy evolved by Leishmania and Plasmodium parasites to evade host immune responses. Here, the effects of co-exposing human monocyte-derived DCs to Leishmania donovani promastigotes and Plasmodium falciparum-infected erythrocytes were investigated. Co-stimulation resulted in a dual, dose-dependent effect on DC differentiation which ranged from semi-mature cells, secreting low interleukin(-12p70 levels to a complete lack of phenotypic maturation in the presence of high parasite amounts. The effect was mainly triggered by the Leishmania parasites, as illustrated by their ability to induce semi-mature, interleukin-10-producing DCs, that poorly responded to lipopolysaccharide stimulation. Conversely, P. falciparum blood-stage forms failed to activate DCs and only slightly interfered with lipopolysaccharide effects. Stimulation with high L. donovani concentrations triggered phosphatidylserine translocation, whose onset presented after initiating the maturation impairment process. When added in combination, the two parasites could co-localize in the same DCs, confirming that the leading effects of Leishmania over Plasmodium may not be due to mutual exclusion. Altogether, these results suggest that in the presence of visceral leishmaniasis-malaria co-infections, Leishmania-driven effects may overrule the more silent response elicited by P. falciparum, shaping host immunity towards a regulatory pattern and possibly delaying disease resolution.