First evidence of the deletion in the pfhrp2 and pfhrp3 genes in Plasmodium falciparum from Equatorial Guinea

Abstract

Background: The World Health Organization (WHO) recommends rapid diagnostic tests (RDTs) as a good alternative malaria-diagnosis method in remote parts of sub-Saharan Africa. The majority of commercial RDTs currently available detect the Plasmodium falciparum protein histidine-rich protein 2 (PfHRP2). There have also been recent reports of pfhrp2 gene deletions being found in parasites collected from several African countries. The WHO has concluded that lacking the pfhrp2 gene must be monitored in Africa. The purpose of the study was to analyse why the samples that were positive by PCR were negative by RDTs and, therefore, to determine whether there have been deletions in the pfhrp2 and/or pfhrp3 genes. Methods: Malaria NM-PCR was carried out on all the samples collected in the field. A group of 128 samples was positive by PCR but negative by RDT; these samples were classified as RDT false-negatives. PCR was carried out for exon2 of pfhrp2 and pfhrp3 genes to detect the presence or absence of these two genes. Frequencies with 95% confidence intervals (CIs) were used for prevalence estimates. Associations were assessed by the Chi square test or Fisher´s exact test. The level of significance was set at p ≤ 0.05. Statistical analyses were performed using the software package SPSSv.15.0. Results: After PCR, 81 samples were identified (4.7%, 95% CI 3.8-5.8) which had deletion in both genes, pfhrp2 and pfhrp3. Overall, however, 11 samples (0.6%, 95% CI 0.36-1.14) had deletion only in pfhrp2 but not in pfhrp3, and 15 (0.9%, 95% CI 0.6-1.5) presented with deletion only in pfhrp3 but not in pfhrp2. Considering the pfhrp2 gene separately, within the total of 1724 samples, 92 (5.3%, 95% CI 4.37-6.5) had evidence of deletion. Conclusion: The present study provides the first evidence of deletion in the pfhrp2 and pfhrp3 genes in P. falciparum isolates from Equatorial Guinea. However, larger studies across different regions within the country and across different seasonal profiles are needed to determine the full extent of pfhrp2 and pfhrp3 deletion. It is strongly recommended to implement an active surveillance programme in order to detect any increases in pfhrp2 and pfhrp3 deletion frequencies.

Plasmodium falciparum isolate with histidine-rich protein 2 gene deletion from Nyala City, Western Sudan

“…By contrast, reports of presence of pfhrp2 gene deletions in West Africa have been limited, including in Mali 12 and Senegal 13 . Recent studies provide evidence of deletion of the pfhrp2 gene as reported from Equatorial Guinea 26 and Nigeria 27 . However, in many highly malaria-endemic countries, data about pfhrp2 deletion are missing.…”

Plasmodium falciparum histidine-rich protein 2 diversity in Ghana

“…Indeed, a recent study in Ghana reported pfhrp2 gene deletion in 33 and 36% of microscopicallyconfirmed and PCR-confirmed RDT positive samples, respectively [21]. Over the past decade, several countries, especially in Africa, have reported cases of P. falciparum isolates with deleted pfhrp2, and isolates with high pfhrp2 diversity [17,18,[22][23][24][25][26], with potential negative implications for malaria control and elimination programmes. These notwithstanding, studies on pfhrp2 gene deletion and diversity of the pfhrp2 gene in Ghana, a malaria-endemic country, are lacking.…”

Malaria Rapid Diagnostic Tests: Literary Review and Recommendation for a Quality Assurance, Quality Control Algorithm

“…HRP 2 deletions were also identified in Honduras and Peru with a 40.6% deletion rate identified in Iquitos, Peru, which makes HRP2 a poor option in that region [ 13 , 23 ]. From 2019–2020, Pf- HRP 2 and HRP3 mutations were reported in 15 countries and confirmed in 11 countries, including: China, Equatorial Guinea, Ethiopia, Ghana, Myanmar, Nigeria, Sudan, Uganda, United Kingdom (imported), Tanzania, Zambia [ 2 , 24 ]. As such, the WHO has recommended that countries with PfHRP2/3 deletions and neighboring countries should “conduct baseline surveys among suspected malaria cases” to determine whether there is a greater than 5% HRP2 deletion rate resulting in false negatives [ 2 ].…”