scholarly journals Plasmodium falciparum is evolving to escape malaria rapid diagnostic tests in Ethiopia

2021 ◽  
Author(s):  
Sindew M. Feleke ◽  
Emily N. Reichert ◽  
Hussein Mohammed ◽  
Bokretsion G. Brhane ◽  
Kalkidan Mekete ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Diagnostic Tests ◽  
Population Expansion ◽  
Selective Advantage ◽  
Rapid Diagnostic Tests ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Diagnostic Strategies ◽  
Malaria Rapid Diagnostic Tests ◽  
Molecular Inversion Probe

AbstractIn Africa, most rapid diagnostic tests (RDTs) for falciparum malaria recognize histidine-rich protein 2 antigen. Plasmodium falciparum parasites lacking histidine-rich protein 2 (pfhrp2) and 3 (pfhrp3) genes escape detection by these RDTs, but it is not known whether these deletions confer sufficient selective advantage to drive rapid population expansion. By studying blood samples from a cohort of 12,572 participants enroled in a prospective, cross-sectional survey along Ethiopia’s borders with Eritrea, Sudan and South Sudan using RDTs, PCR, an ultrasensitive bead-based immunoassay for antigen detection and next-generation sequencing, we estimate that histidine-rich protein 2-based RDTs would miss 9.7% (95% confidence interval 8.5–11.1) of P. falciparum malaria cases owing to pfhrp2 deletion. We applied a molecular inversion probe-targeted deep sequencing approach to identify distinct subtelomeric deletion patterns and well-established pfhrp3 deletions and to uncover recent expansion of a singular pfhrp2 deletion in all regions sampled. We propose a model in which pfhrp3 deletions have arisen independently multiple times, followed by strong positive selection for pfhrp2 deletion owing to RDT-based test-and-treatment. Existing diagnostic strategies need to be urgently reconsidered in Ethiopia, and improved surveillance for pfhrp2 deletion is needed throughout the Horn of Africa.

scholarly journals Emergence and evolution of Plasmodium falciparum histidine-rich protein 2 and 3 deletion mutant parasites in Ethiopia

2021 ◽  
Author(s):  
Sindew M. Feleke ◽  
Emily N. Reichert ◽  
Hussein Mohammed ◽  
Bokretsion G. Brhane ◽  
Kalkidan Mekete ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Falciparum Malaria ◽  
Diagnostic Tests ◽  
Deletion Mutant ◽  
Diagnostic Testing ◽  
Rapid Diagnostic Tests ◽  
Horn Of Africa ◽  
Diagnostic Strategies ◽  
Genomic Tools ◽  
Subtelomeric Deletion

AbstractMalaria diagnostic testing in Africa is threatened by Plasmodium falciparum parasites lacking histidine-rich protein 2 (pfhrp2) and 3 (pfhrp3) genes. Among 12,572 subjects enrolled along Ethiopia’s borders with Eritrea, Sudan, and South Sudan and using multiple assays, we estimate HRP2-based rapid diagnostic tests would miss 9.7% (95% CI 8.5-11.1) of falciparum malaria cases due to pfhrp2 deletion. Established and novel genomic tools reveal distinct subtelomeric deletion patterns, well-established pfhrp3 deletions, and recent expansion of pfhrp2 deletion. Current diagnostic strategies need to be urgently reconsidered in Ethiopia, and expanded surveillance is needed throughout the Horn of Africa.

scholarly journals PO 8271 PFHRP2 GENE DELETIONS IN PLASMODIUM FALCIPARUM AND SCHISTOSOMA MANSONI CO-INFECTIONS: AN EMERGING CHALLENGE FOR MALARIA RAPID DIAGNOSTIC TESTS

2019 ◽  
Vol 4 (Suppl 3) ◽  
pp. A25.2-A25
Author(s):  
Hilda Echelibe ◽  
Masumbe Netongo Palmer ◽  
Nji Akindeh ◽  
Wilfred Mbacham
Keyword(s):  
Plasmodium Falciparum ◽  
Schistosoma Mansoni ◽  
Diagnostic Tests ◽  
False Negative ◽  
Rapid Diagnostic Tests ◽  
Sub Saharan Africa ◽  
P Value ◽  
Gene Deletions ◽  
Malaria Rdts ◽  
Malaria Rapid Diagnostic Tests

BackgroundMalaria and schistosomiasis are infections that have a great impact in sub-Saharan Africa based on their high morbidity and mortality rates. We suggest the possibility that the microenvironment created from interactions between the parasites involved generates a pressure on the malaria parasite which could in turn favour the parasite’s adaptation or escape through Pfhrp2 gene deletions. Thus, this study aimed at determining the association between the co-infection with both parasites and false-negative PfHRP2-based malaria rapid diagnostic tests which occur because of these deletions.MethodsThis pilot study was conducted in a total of 149 children aged 7–17 years living in Yorro, located in the Mbam-Inoubou division of the Center region of Cameroon. We collected fresh stool samples from each participant to identify Schistosoma mansoni (Sm) eggs by Kato Katz method and blood samples to identify the ring stages of Plasmodium falciparum (Pf) by thick smear. Malaria rapid diagnostic test and Pfhrp2 gene polymerase chain reaction were performed. The association between the co-infection with Sm/Pf and the false-negative malaria RDTs was determined by the Fisher’s exact test. A p value<0.05 was considered statistically significant.ResultsOur results showed that samples were singly infected with Sm, Pf, co-infected (Sm/Pf) and negative for both infections at frequencies of 12%, 43%, 30.2% and 14.8% respectively. False-negative PfHRP2-based RDTs were observed in 4.7% of the participants. A higher frequency (5/7) of the cases with false-negative malaria RDTs were co-infected with Sm/Pf. A p value of 0.027 showed statistical significance in the association of Sm/Pf co-infection and false-negative PfHRP2-based RDTs.ConclusionA significant association of Plasmodium falciparum and Schistosoma mansoni co-infection with false-negative PfHRP2-based RDTs supports the case for a plausible implication of Pfhrp2 gene deletions, with consequences for malaria rapid diagnostic testing.

scholarly journals Baseline Malaria Prevalence at the Targeted Pre-elimination Districts in Ethiopia

2020 ◽  
Author(s):  
Desalegn Nega ◽  
Adugna Abera ◽  
Bokretsion Gidey ◽  
Sindew Mekasha ◽  
Abnet Abebe ◽  
...  
Keyword(s):  
Malaria Elimination ◽  
Diagnostic Tests ◽  
Open Data ◽  
Malaria Prevalence ◽  
Rapid Diagnostic Tests ◽  
Cross Sectional Survey ◽  
Axillary Temperature ◽  
Cross Sectional ◽  
Low Transmission ◽  
Total Prevalence

Abstract Background: Encouraged by the success in malaria control and prevention strategies, several malaria endemic countries have adopted elimination strategies worldwide. Accordingly, Ethiopian ministry of health launched malaria elimination with a stepwise approach by primarily targeting the low-transmission districts and their adjacent areas/zones in order to shrink the country’s malaria map progressively. Hence, this community survey was conducted to establish baseline malaria information at the preliminary phase of elimination for measuring future intervention success in elimination goal. Methods: Community based cross-sectional survey was conducted at twenty malaria elimination targeted districts selected from five regional states and one city administration in Ethiopia. The GPS enabled smart phones programmed with Open Data Kit were used to enumerate 9326 study households and collect data from 29,993 residents. Care Start™ Malaria HRP-2/PLDH Rapid Diagnostic Tests (RDTs) were used for blood testing at field level. Armpit digital thermometers were used to measure axillary temperature.Result: Overall malaria prevalence by RDTs was 1.17% (339/28973). The prevalence at district levels ranged from 0.0% to 4.7%. The total prevalence of febrile cases (axillary temperature >37.5oc) in the survey was 9.2% (2760/29993). Among the 2,510 febrile individuals tested with RDTs, only 3.35% (84/2510) were malaria positive. Among all study participants, 0.88% (255/28973) malaria positives were afebrile and 0.29% (84/28973) were febrile individuals. The 75.2% (255/339) of all malaria positives were afebrile. Of the total afebrile malaria cases, 10.2% (26/255) were under-five children and 89.8% (229/255) were above 5 years of age. Conclusion: The 1.17% malaria prevalence that ranges 0 to 4% in some districts by rapid diagnostic tests should be given due consideration by the elimination program. Especially the higher prevalence of afebrile individuals (0.88%) in these transmission settings indicates there may be sustaining hidden transmission. Therefore, active case detection with more sensitive diagnostic techniques than this conventional method is suggested to know more real magnitude of residual malaria in the elimination targeted low transmission areas and break the chain of transmission.

scholarly journals Deletions of pfhrp2 and pfhrp3 genes were uncommon in rapid diagnostic test-negative Plasmodium falciparum isolates from Uganda

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Sam L. Nsobya ◽  
Andrew Walakira ◽  
Elizabeth Namirembe ◽  
Moses Kiggundu ◽  
Joaniter I. Nankabirwa ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Protein Expression ◽  
Diagnostic Tests ◽  
False Negative ◽  
Pcr Amplification ◽  
Rapid Diagnostic Tests ◽  
False Negatives ◽  
Cross Sectional ◽  
True Prevalence ◽  
Blood Smears

Abstract Background Rapid diagnostic tests (RDTs) play a key role in malaria case management. The most widely used RDT identifies Plasmodium falciparum based on immunochromatographic recognition of P. falciparum histidine-rich protein 2 (PfHRP2). Deletion of the paralogous pfhrp2 and pfhrp3 genes leads to false-negative PfHRP2-based RDTs, and has been reported in P. falciparum infections from South America and Africa. However, identification of pfhrp2/pfhrp3 deletions has usually been based only on failure to amplify these genes using PCR, without confirmation based on PfHRP2 protein expression, and understanding of the true prevalence of deletions is incomplete. Methods Deletions of pfhrp2/pfhrp3 in blood samples were investigated from cross-sectional surveys in 2012-13 in three regions of varied malaria transmission intensity in Uganda. Samples with positive Giemsa-stained thick blood smears, but negative PfHRP2-based RDTs were evaluated by PCR amplification of conserved subunit ribosomal DNA for Plasmodium species, PCR amplification of pfhrp2 and pfhrp3 genes to identify deletions, and bead-based immunoassays for expression of PfHRP2. Results Of 3516 samples collected in cross-sectional surveys, 1493 (42.5%) had positive blood smears, of which 96 (6.4%) were RDT-negative. Of these 96 RDT-negative samples, P. falciparum DNA was identified by PCR in 56 (58%) and only non-falciparum plasmodial DNA in 40 (42%). In all 56 P. falciparum-positive samples there was a failure to amplify pfhrp2 or pfhrp3: in 25 (45%) pfhrp2 was not amplified, in 39 (70%) pfhrp3 was not amplified, and in 19 (34%) neither gene was amplified. For the 39 P. falciparum-positive, RDT-negative samples available for analysis of protein expression, PfHRP2 was not identified by immunoassay in only four samples (10.3%); these four samples all had failure to amplify both pfhrp2 and pfhrp3 by PCR. Thus, only four of 96 (4.2%) smear-positive, RDT-negative samples had P. falciparum infections with deletion of pfhrp2 and pfhrp3 confirmed by failure to amplify the genes by PCR and lack of expression of PfHRP2 demonstrated by immunoassay. Conclusion False negative RDTs were uncommon. Deletions in pfhrp2 and pfhrp3 explained some of these false negatives, but most false negatives were not due to deletion of the pfhrp2 and pfhrp3 genes.

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