# name
Utility of ultra-sensitive qPCR to detect Plasmodium falciparum and Plasmodium vivax infections under different transmission
intensities

# metadata.dc.description.abstract[].value
Background: The use of molecular diagnostics has revealed an unexpectedly large number of asymptomatic
low-density malaria infections in many malaria endemic areas. This study compared the gains in parasite prevalence
obtained by the use of ultra-sensitive (us)-qPCR as compared to standard qPCR in cross-sectional surveys conducted
in Thailand, Brazil and Papua New Guinea (PNG). The compared assays differed in the copy number of qPCR targets in
the parasite genome.
Methods: Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) parasites were quantified by qPCR amplifying the
low-copy Pf_ and Pv_18S rRNA genes or the multi-copy targets Pf_varATS and Pv_mtCOX1. Cross-sectional surveys at
the three study sites included 2252 participants of all ages and represented different transmission intensities.
Results: In the two low-transmission areas, P. falciparum positivity was 1.3% (10/773) (Thailand) and 0.8% (5/651) (Bra-
zil) using standard Pf_18S rRNA qPCR. In these two countries, P. falciparum positivity by Pf_varATS us-qPCR increased
to 1.9% (15/773) and 1.7% (11/651). In PNG, an area with moderate transmission intensity, P. falciparum positivity
significantly increased from 8.6% (71/828) by standard qPCR to 12.2% (101/828) by us-qPCR. The proportions of P.
falciparum infections not detected by standard qPCR were 33%, 55% and 30% in Thailand, Brazil and PNG. Plasmodium
vivax was the predominating species in Thailand and Brazil, with 3.9% (30/773) and 4.9% (32/651) positivity by Pv_18S
rRNA qPCR. In PNG, P. vivax positivity was similar to P. falciparum, at 8.0% (66/828). Use of Pv_mtCOX1 us-qPCR led to
a significant increase in positivity to 5.1% (39/773), 6.4% (42/651) and 11.5% (95/828) in Thailand, Brazil, and PNG. The
proportions of P. vivax infections missed by standard qPCR were similar at all three sites, with 23%, 24% and 31% in
Thailand, Brazil and PNG.
Conclusion: The proportional gains in the detection of P. falciparum and P. vivax infections by ultra-sensitive diag-
nostic assays were substantial at all three study sites. Thus, us-qPCR yields more precise prevalence estimates for
both P. falciparum and P. vivax at all studied levels of endemicity and represents a significant diagnostic improvement.

# metadata.dc.source[].value
Articles publicats en revistes (ISGlobal)

# metadata.dc.title[].value
Utility of ultra-sensitive qPCR to detect Plasmodium falciparum and Plasmodium vivax infections under different transmission
intensities