Background
False negative rapid diagnostic tests (RDTs) accruing to the non-detection of
Plasmodium falciparum
histidine-rich protein 2/3 (Pfhrp2/3) is threatening the diagnosis and management of malaria. Although regular monitoring is necessary to gauge the level of efficacy of the tool, studies in Cameroon remain limited. This study assessed
Plasmodium
spp. prevalence and
Pfhrp2/3
gene deletions across ecological and transmission zones in Cameroon.
Methods
This is a cross-sectional, multi-site, community- and hospital- based study, in 21 health facilities and 14 communities covering all five ecological settings in low seasonal (LS) and intense perennial (IPT) malaria transmission zones between 2019 and 2021. Participants were screened for malaria parasite using Pfhrp2 RDT and light microscopic examination of thick peripheral blood smears. DNA was extracted from dried blood spot using chelex
®
-100 and
P. falciparum
confirmed using
var
ATS real-time quantitative Polymerase Chain Reaction (qPCR),
P. malariae
and
P. ovale
by real-time qPCR of Plasmepsin gene, and
P. vivax
using a commercial kit. Isolates with amplified
Pfcsp
and
Pfama-1
genes were assayed for
Pfhrp 2/3
gene deletions by conventional PCR.
Results
A total of 3,373 participants enrolled, 1,786
Plasmodium
spp. infected, with 77.4%
P. falciparum
. Discordant RDT and qPCR results (False negatives) were reported in 191 (15.7%)
P
.
falciparum
mono-infected samples from LS (29%, 42) and IPT (13.9%, 149). The
Pfhrp2
+/
Pfhrp3
+ genotype was most frequent, similar between LS (5.5%, 8/145) and IPT (6.0%, 65/1,076). Single
Pfhrp2
and
Pfhrp3
gene deletions occurred in LS (0.7%, 1/145 each) and IPT (3.6%, 39/1,076 vs. 2.9%, 31/1,076), respectively. Whilst a single sample harboured
Pfhrp2
-/
Pfhrp3
- genotype in LS, 2.4% (26/1,076) were double deleted at IPT.
Pfhrp2
+/
Pfhrp3
- (0.3%, 3/1,076) and
Pfhrp2
-/
Pfhrp3
+ (1.2%, 13/1,076) genotypes were only observed in IPT.
Pfhrp2
,
Pfhrp3
deletions and
Pfhrp2-/Pfhrp3-
genotype accounted for 78.8% (26), 69.7% (23) and 63.6% (21) RDT false negatives, respectively.
Conclusion
Plasmodium falciparum
remains the most dominant and widely ...