Malaria Ag Research Articles

Association of first-line combination antiretroviral therapy with malaria among adult HIV-infected persons in Jos, Nigeria: a pilot cross sectional study

BackgroundMalaria and human immunodeficiency virus (HIV) infection coexist in significant numbers in some geographic areas including sub-Sahara Africa (SSA). HIV-infected patients are a World Health Organization (WHO) recognized high risk group for increased malaria morbidity. Majority of HIV-infected patients undertaking treatment in SSA are on WHO recognized first-line combination antiretroviral therapy (cART). Considering the immunity-enhancing capacity of antiretroviral therapies on people living with HIV, this study aimed to explore the association between first-line combination antiretroviral therapy (cART) with malaria parasitaemia and antigenaemia in adult HIV-infected persons and to determine the predictors of malaria antigenaemia in adult persons living with HIV.MethodsThe study was conducted at the AIDS Prevention Initiative in Nigeria (APIN) Centre, Jos University Teaching Hospital, Jos, Plateau State, from August 2018 to February 2019. Epi Info statistical tool was used to determine the sample size and power of the study. The study population consisted of three groups. The first group comprised first-line cART-experienced adult HIV-seropositive subjects, the second group comprised ARV-naïve HIV-seropositive adults and the third group comprised HIV-seronegative adults. For this pilot study, 60 persons were recruited into each group via convenience sampling. Malaria rapid diagnostic test (RDT) was performed according to manufacturer’s instruction for all the study participants using SD Bioline Malaria Ag P.f (HRP2/pLDH) (Standard Diagnostics, Hagal-Dong, Korea). All the study participants also had thick and thin blood film malaria microscopy. Data collected was processed and analyzed using the Stata statistical software version 15 (StataCorp, College Station, Texas). Chi square was used to test the association between malaria and first-line cART exposure. Univariate and multivariate analysis were also done to identify factors that were independently associated with malaria antigenaemia.ResultsA total of 180 persons participated in the study and involved 60 participants recruited in each of the three study groups. Overall, the predominant study participants were females (56.67%), traders (27.78%), secondary school leavers (43.33%) and urban dwellers (88.89%). Their mean age and standard deviation was 37.07 ± 11.53 years. Using malaria microscopy, the prevalence of malaria parasitaemia in ARV-naïve HIV-infected persons was 5% and 0% in the first-line cART-experienced HIV-infected persons as well as the HIV-negative persons. Malaria RDT result was positive in 7/60 (11.67%) of the first-line cART experienced HIV-infected participants, 6/60 (10%) of the ARV-naïve HIV-infected group and 1/60 (1.67%) of the HIV-negative group. Of the seven positive malaria RDT results in those on first-line cART, five persons were receiving zidovudine/lamivudine/nevirapine (AZT/3TC/NVP) while the remaining two were receiving tenofovir disoproxil fumarate/lamivudine/efavirenz (TDF/3TC/EFV), thus making an antigenaemia proportion of 16.67% and 6.67% respectively. Being an HIV-infected person on first-line cART (OR = 16.20, p = 0.04), having a headache (OR = 6.21, p = 0.03) and non-usage of window nets (OR = 3.74, p = 0.05) were found to be predictors of malaria antigenaemia.ConclusionMalaria parasite burden in HIV-infected persons on first-line cART is lower than that observed in ARV-naïve HIV-infected persons. Our study suggests that TDF/3TC/EFV may be associated with lower malaria antigenaemia when compared with AZT/3TC/NVP and can be considered an alternative first-line antiretroviral regimen in malaria-endemic regions.

Analytical Sensitivity Analysis and Clinical Impact Modeling of Rapigen Rapid Diagnostic Tests for Malaria.

Laboratory benchmarking allows objective analysis of the analytical performance of malaria rapid diagnostic tests (RDTs). We present the analytical detection limits of the Rapigen BIOCREDIT Malaria Ag Pf/Pv (pLDH/pLDH), the Rapigen BIOCREDIT Malaria Ag Pf (pLDH/HRPII), and two best-in-class WHO-prequalified comparator RDTs, generated using standardized panels containing recombinant antigen, invitro cultured parasites, international standards, and clinical samples. Detection limit antigen concentrations of HRP2, PfLDH, and PvLDH were determined for the Rapigen and comparator RDTs. Detection of antigens in international units (IU)/mL was also evaluated. The Rapigen Ag Pf (pLDH/HRPII) detected 3.9 and 3.9 IU/mL for PfLDH and HRP2, respectively, and the Ag Pf/Pv (pLDH/pLDH) detected 3.9 and 5.0 IU/mL for PfLDH and PvLDH, respectively. The comparator HRP2/PfLDH and HRP2/PvLDH detected 15.6 and 31.3 IU/mL for HRP2 and PfLDH and 15.6 and 50.0 IU/mL for HRP2 and PvLDH, respectively. The RDT clinical sensitivity was predicted through application of analytical detection limits to antigen concentration distributions from clinical symptomatic and asymptomatic cases. Febrile cases would be detected in a majority by both standard and Rapigen RDTs, but incremental increases in sensitivity in the Rapigen RDTs may be important for clinical cases currently missed by microscopy. Rapigen RDTs were predicted to have improved detection of asymptomatic cases and infections with parasites carrying hrp2 deletions through more sensitive PfLDH detection. Through the benchmarking and simulation of clinical sensitivity, a method for rapidly assessing the ability of new RDTs to meet clinical needs using high-sensitivity antigen distribution data is presented.

Comparison of three rapid diagnostic tests for Plasmodium falciparum diagnosis in Ghana

BackgroundAccurate diagnosis and timely treatment are crucial in combating malaria.MethodsA total of 449 samples were screened for Plasmodium falciparum infection by expert microscopy, qPCR, and three RDTs, namely Rapigen Biocredit Malaria Ag Pf (detecting HRP2 and pLDH on separate bands), Abbott NxTek Eliminate Malaria Ag Pf (detecting HRP2), and SD Bioline Malaria Ag Pf (detecting HRP2). hrp2/3 deletion typing was done by digital PCR.Results45.7% (205/449) individuals tested positive by qPCR for P. falciparum with a mean parasite density of 12.5 parasites/μL. Using qPCR as reference, the sensitivity of microscopy was 28.3% (58/205), the Biocredit RDT was 52.2% (107/205), the NxTek RDT was 49.3% (101/205), and the Bioline RDT was 39.5% (81/205). When only samples with densities > 20 parasites/μL were included (n = 89), sensitivity of 62.9% (56/89) by microscopy, 88.8% (79/89) by Biocredit, 88.8% (79/89) by NxTek, and 78.7% (70/89) by Bioline were obtained. All three RDTs demonstrated specificities > 95%. The limits of detection (95% probability that a sample tested positive) was 4393 parasites/μL (microscopy), 56 parasites/μL (Biocredit, considering either HRP2 or pLDH), 84 parasites/μL (NxTek), and 331 parasites/μL (Bioline). None of the three qPCR-confirmed P. falciparum positive samples, identified solely through the pLDH target, or eight samples negative for all RDTs but qPCR-positive at densities > 20 parasites/µL carried hrp2/3 deletions.ConclusionThe Biocredit and NxTek RDTs demonstrated comparable diagnostic efficacies. All three RDTs performed better than microscopy.

Performance evaluation of a combination Plasmodium dual-antigen CRP rapid diagnostic test in Lambaréné, Gabon.

The consequent use of malaria rapid diagnostic tests (RDTs) preceding a treatment decision has improved the global management of malaria. A combination RDT, including an inflammation marker to potentially guide antibiotic prescription, could improve the management of acute febrile illness (AFI). We performed a prospective, cross-sectional study in Gabon evaluating the STANDARD Malaria/CRP DUO (S-DUO) RDT. Participants aged 2 to 17 years with fever at presentation and/or a history of fever < 7 days were enrolled. Expert microscopy, SD Bioline Malaria Ag P.f/Pan test for malaria detection, and NycoCard CRP device for CRP were used as comparators. AFI cases were classified on a spectrum encompassing bacterial vs. non-bacterial infection. 415 participants with AFI were enrolled. S-DUO RDT sensitivity and specificity for malaria detection vs. microscopy were 99·1% (95·2-100%) and 72·7% (64·3-80·1%); and for CRP detection (20mg/L and above) 86·9% (80-92%) and 87% (79·2-92·7%), respectively. The difference in CRP levels between bacterial infection (mean = 41·2mg/L) and other causes of fever, measured from our study population using the Nycocard device, was statistically significant (p < 0·01); CRP precision-recall AUC to distinguish bacterial infection class vs. non-bacterial classifications was 0·79. S-DUO RDT is suitable for malaria detection in moderate-to-high malaria transmission settings such as in Lambaréné; however, a CRP band detection limit > 40mg/L is more adequate for indication of antibiotic prescription for AFI cases in Gabon.

Sub-microscopic Plasmodium falciparum infections and multiple drug resistant single nucleotide polymorphic alleles in pregnant women from southwestern Nigeria

ObjectivesThe study evaluated sub-microscopic malaria infections in pregnancy using two malaria Rapid Diagnostic Tests (mRDTs), microscopy and RT-PCR and characterized Plasmodium falciparum dihydrofolate reductase (Pfdhfr) and Plasmodium falciparum dihydropteroate synthase (Pfdhps) drug resistant markers in positive samples.MethodsThis was a cross sectional survey of 121 pregnant women. Participants were finger pricked, blood drops were collected for rapid diagnosis with P. falciparum histidine-rich protein 11 rapid diagnostic test kit and the ultra-sensitive Alere Pf malaria RDT, Blood smears for microscopy and dried blood spots on Whatman filter paper for molecular analysis were made. Real time PCR targeting the var acidic terminal sequence (varATS) gene of P. falciparum was carried out on a CFX 96 real time system thermocycler (BioRad) in discriminating malaria infections. For each run, laboratory strain of P. falciparum 3D7 and nuclease free water were used as positive and negative controls respectively. Additionally, High resolution melt analyses was employed for genotyping of the different drug resistance markers.ResultsOut of one hundred and twenty-one pregnant women sampled, the SD Bioline™ Malaria Ag P.f HRP2-based malaria rapid diagnostic test (mRDT) detected eight (0.06%) cases, the ultra-sensitive Alere™ malaria Ag P.f rapid diagnostic test mRDT had similar outcome in the same samples as detected by the HRP2-based mRDT. Microscopy and RT-PCR confirmed four out of the eight infections detected by both rapid diagnostic tests as true positive and RT-PCR further detected three false negative samples by the two mRDTs providing a sub-microscopic malaria prevalence of 3.3%. Single nucleotide polymorphism in Pfdhps gene associated with sulphadoxine resistance revealed the presence of S613 mutant genotypes in three of the seven positive isolates and isolates with mixed wild/mutant genotype at codon A613S. Furthermore, four mixed genotypes at the A581G codon were also recorded while the other Pfdhps codons (A436G, A437G and K540E) showed the presence of wild type alleles. In the Pfdhfr gene, there were mutations in 28.6%, 28.6%, and 85.7% at the I51, R59 and N108 codons respectively. Mixed wild and mutant type genotypes were also observed in 28.6% each of the N51I, and C59R codons. For the Pfcrt, two haplotypes CVMNK and CVIET were observed. The SVMNT was altogether absent. Triple mutant CVIET 1(14.3%) and triple mutant + wild genotype CVIET + CVMNK 1(14.3%) were observed. The Pfmdr1 haplotypes were single mutants YYND 1(14.3%); NFND 1(14.3%) and double mutants YFND 4(57.1%); YYDD 1(14.3%).

Comparison of SD Bioline Malaria Ag Pf/Pan and Acro Malaria P.f./P.v./Pan with Microscopy and Real Time PCR for the Diagnosis of Human Plasmodium Species.

The early diagnosis of malaria is crucial to controlling morbidity and mortality. The World Health Organization (WHO) recommends diagnosing malaria either using light microscopy or a malaria rapid diagnostic test (RDT). Most RDTs use antibodies to detect two P. falciparum histidine-rich proteins named PfHRP2 and PfHRP3. However, false-negative results are known to occur due to the poor performance of RDTs depending on the species and the deletion of the Pfhrp2 and Pfhrp3 genes. This study evaluated new malaria RDTs for the detection of the human Plasmodium species. The Acro Malaria P.f./P.v./Pan Rapid Test Cassette allows the qualitative detection of parasite antigens, such as PfHRP2 specific to Plasmodium falciparum, PvLDH specific to Plasmodium vivax, and/or panLDH Plasmodium genus lactate dehydrogenase, in the blood of infected individuals. This RDT was assessed against 229 samples collected from imported malaria cases, mainly from Africa. The samples were previously diagnosed using light microscopy and RDT (SD Malaria Ag P.f./Pan, SD Bioline Alere Abbott), then confirmed using real time PCR. The two RDTs were evaluated using a comparison with real time PCR as the reference method, and their performances were compared with each other. Compared to SD RDT, the Acro RDT showed a better sensitivity to P. falciparum (96.8% vs. 89.8%), P. vivax (78.6% vs. 64.3%), P. ovale (73.7% vs. 5.3%), and P. malariae (20.0% vs. 0%). The respective specificities of the Acro RDT and SD RDT are 90.7% vs. 95.3% to P. falciparum, 100% to P. vivax, and 100% vs. 100% to Plasmodium genus. Therefore, Acro RDT showed better performance in the identification of P. ovale and low parasitaemia of P. falciparum. In addition, Acro RDT has the advantage of detecting PvLDH-specific antigens. The Acro Malaria RDT presents the benefits of detecting a P. falciparum antigen (PfHRP2) and a P. vivax antigen (PvLDH) with high sensitivity (96.8% and 73.7%, respectively) and specificity (90.7% and 100%, respectively). Acro Malaria P.f./P.v./Pan rapid diagnostic tests could be effectively used in endemic areas, especially when microscopic examination cannot be performed.

Malaria infection and predictor factors among Chadian nomads’ children

BackgroundIn Chad, malaria remains a significant public health concern, particularly among nomadic populations. Geographical factors and the mobility of human populations have shown to be associated with the diversity of Plasmodium species. The study aims to describe the malaria prevalence among nomadic children and to investigate its associated factors.MethodsA cross-sectional study was conducted in February and October 2021 among nomadic communities in Chad. Blood sample were collected and tested from 187 Arab, Fulani and Dazagada nomadic children aged 3–59 months using malaria rapid diagnostic test (RDT). A structured electronic questionnaire was administered to their parents to collect information about the socio‑economic data. Malaria testing results were categorized according to the SD BIOLINE Malaria Ag Pf/Pan RDT procedures. Logistic regression analysis was used to determine key risk factors explaining the prevalence of malaria. STATA version IC 13 was used for statistical analysis.ResultsThe overall malaria prevalence in nomadic children was 24.60%, with 65.20% being Plasmodium falciparum species and 34.8% mixed species. Boys were twice as likely (COR = 1.83; 95% CI, 0.92–3.62; p = 0.083) to have malaria than girls. Children whose parents used to seek traditional drugs were five times more likely (AOR = 5.59; 95% CI, 1.40–22.30, p = 0.015) to have malaria than children whose parents used to seek health facilities. Children whose parents reported spending the last night under a mosquito net were one-fifth as likely (AOR = 0.17; 95% CI, 0.03–0.90, p = 0.037) to have malaria compared to children whose parents did not used a mosquito net. Furthermore, Daza children were seventeen times (1/0.06) less likely (AOR = 0.06; 95% CI, 0.01–0.70, p = 0.024) to have malaria than Fulani children and children from households piped water as the main source were seven times more likely (AOR = 7.05; 95% CI, 1.69–29.45; p = 0.007) to have malaria than those using surface water.ConclusionsMalaria remains a significant public health issue in the nomadic communities of Chad. Community education and sensitization programs within nomad communities are recommended to raise awareness about malaria transmission and control methods, particularly among those living in remote rural areas. The National Malaria Control Program (NMCP) should increase both the coverage and use of long-lasting insecticidal nets (LLINs) and seasonal malaria chemoprevention (SMC) in addition to promoting treatment-seeking behaviors in nomadic communities.

Investigation of Sensitivity of Rapid Diagnosis Tests in Patients with Suspected Malaria.

Malaria has been eradicated in Türkiye as of 2010, but there are imported cases. In this study, we aimed to compare the diagnostic value of two rapid tests; SD Bioline Malaria Ag Pf/Pan (SD-Pf/Pan) and SD Bioline Malaria Ag Pf/Pv (SD-Pf/Pv) with microscopy and real time-polymerase chain reaction (RT-PCR). Blood samples were taken from all participants. Thick drop smears were prepared. Thick drop smears were examined for malaria positive/negative distinction under the light microscopy. Then, two rapid diagnostic tests (SD-Pf/Pan and SD-Pf/Pv) were performed. After DNA extraction from blood samples, RT-PCR was typed. The data were evaluated with SPSS 21 program of statistics. A total of 30 cases out of 66 suspected malaria cases were detected as positive with microscopy and RT-PCR. Twenty-seven patients were found positive with both SD-Pf/Pan and SD-Pf/Pv tests. Based on the microscopic results as a reference method, SD-Pf/Pan and SD-Pf/Pv rapid diagnostic tests had a 90% sensitivity, 100% specificity, 100% positive predictive value (PPV), and 92.86% negative predictive value (NPV). Based on the RT-PCR results as a reference method, for detection of P. falciparum, both tests had a 95.65% sensitivity, 100% specificity, 100% PPV, and 88.89% NPV. Moreover, while SD-Pf/Pv had a sensitivity, specificity, PPV, and NPV of 100% in detection of P. vivax; SD-Pf/Pan has a 77.78% sensitivity of, 61.90% specificity of, 46.67% PPV, and 86.67% NPV SD-Pf/Pan for detection of PAN. As a result, high sensitivity and specificity were detected in both kits in the diagnosis of malaria infections caused by P. falciparum and P. vivax. Rapid diagnostic tests can be used safely in diagnosis however the diagnosis should be supported by microscopy and RT-PCR methods when they are applicable.

Concurrent infection of dengue virus with malaria parasites among outpatients attending healthcare facilities in Benin city, Nigeria.

Dengue virus (DENV) and malaria parasites (MP) are among the common febrile diseases affecting the tropics and subtropics of the world. Both are mosquito-borne pathogens affecting humans and other animals. Blood samples were collected from 280 consented out-patients attending the selected hospitals and were analyzed. Malaria parasites were detected using microscopy and Malaria Ag Pf/Pan Rapid Test Device. Dengue virus was detected by serology and heminested reverse transcriptase PCR (hnRT-PCR) to target the flavivirus polymerase (NS5) gene. Malaria parasites recorded a total positivity of 151 patients (53.9%) using microscopy, while DENV antibodies (DENV IgM and DENV IgG) were positive in 16 (5.7%) and 39 (13.9%) patients, respectively. There was a concurrent infection between MP/DENV IgM in 13 (4.6%) patients and MP/DENV IgG in 27 (9.6%) patients. Molecular identification revealed DENV serotype 2 in circulation. This study documents molecular evidence of dengue virus coexisting with malaria parasites in the study population, hence the need for efficient surveillance and control system.

Assessment of the Performance of Lactate Dehydrogenase-Based Rapid Diagnostic Test for Malaria in Djibouti in 2022–2023

Until 2020, Djiboutian health authorities relied on histidine-rich protein-2 (HRP2)-based rapid diagnostic tests (RDTs) to establish the diagnosis of Plasmodium falciparum. The rapid spread of P. falciparum histidine-rich protein-2 and -3 (pfhrp2/3) gene-deleted parasite strains in Djibouti has led the authorities to switch from HRP2-based RDTs to lactate dehydrogenase (LDH)-based RDTs targeting the plasmodial lactate dehydrogenase (pLDH) specific for P. falciparum and P. vivax (RapiGEN BIOCREDIT Malaria Ag Pf/Pv pLDH/pLDH) in 2021. This study was conducted with the primary objective of evaluating the diagnostic performance of this alternative RDT. Operational constraints related, in particular, to the implementation of this RDT during the COVID-19 pandemic were also considered. The performance of BIOCREDIT Malaria Ag Pf/Pv (pLDH/pLDH) RDT was also compared to our previously published data on the performance of two HRP2-based RDTs deployed in Djibouti in 2018–2020. The diagnosis of 350 febrile patients with suspected malaria in Djibouti city was established using two batches of RapiGEN BIOCREDIT Malaria Ag Pf/Pv (pLDH/pLDH) RDT over a two-year period (2022 and 2023) and confirmed by real-time quantitative polymerase chain reaction. The sensitivity and specificity for the detection of P. falciparum were 88.2% and 100%, respectively. For P. vivax, the sensitivity was 86.7% and the specificity was 100%. Re-training and closer supervision of the technicians between 2022 and 2023 have led to an increased sensitivity to detect P. falciparum (69.8% in 2022 versus 88.2% in 2023; p &lt; 0.01). The receiver operating characteristic curve analysis highlighted a better performance in the diagnosis of P. falciparum with pLDH-based RDTs compared with previous HRP2-based RDTs. In Djibouti, where pfhrp2-deleted strains are rapidly gaining ground, LDH-based RDTs seem to be more suitable for diagnosing P. falciparum than HRP2-based RDTs. Awareness-raising and training for technical staff have also been beneficial.

Diagnostic performance of ultrasensitive rapid diagnostic test for the detection of Plasmodium falciparum infections in asymptomatic individuals in Kisangani, Northeast Democratic Republic of Congo

BackgroundUltrasensitive rapid diagnostic test (usRDT) was recently developed to improve the detection of low-density Plasmodium falciparum infections. However, its diagnostic performance has not been evaluated in the Democratic Republic of Congo (DRC). This study aims to determine the performance of the usRDT in malaria diagnosis in asymptomatic individuals under field condition in Kisangani, Northeast of DRC.MethodsA community-based cross-sectional study was carried out from June to August 2022 on 312 asymptomatic individuals residing in the city of Kisangani. Capillary blood samples were collected by finger prick for microscopic examination of thick and thin blood film, RDTs, and nested polymerase chain reaction (PCR). Alere™ Malaria Ag P.f usRDT and conventional RDT (cRDT/SD Bioline Malaria Ag P.f) kits were used for the detection of Plasmodium histidine rich protein 2 (HRP2) antigen as a proxy for the presence of P. falciparum. The diagnostic performance of the usRDT was compared with cRDT, microscopy and PCR.ResultsThe prevalence of asymptomatic P. falciparum malaria was 40.4%, 42.0%, 47.1% and 54.2% by cRDT, microscopy, usRDT and PCR, respectively. By using PCR as a reference, usRDT had sensitivity and specificity of 87.0% (95% CI 81.4–91.7) and 100.0% (95% CI 97.5–100.0), respectively, whereas the cRDT had sensitivity and specificity of 74.6% (95% CI 67.3–80.9) and 100% (95% CI 97.1–100.0), respectively. By using microscopy as a reference, usRDT had sensitivity and specificity of 96.9% (95% CI 92.4–99.2) and 89.0% (95% CI 83.5–93.1), respectively, while the cRDT had sensitivity and specificity of 96.2% (95% CI 92.3–98.7) and 100% (95% CI 97.9–100.0), respectively.ConclusionThe usRDT showed better diagnostic performance with higher sensitivity than the cRDT which is currently in use as point-of-care test. Further research is necessary to assess the access and cost-effectiveness of the usRDTs to use for malaria surveillance.

Schoolchildren with asymptomatic malaria are potential hotspot for malaria reservoir in Ethiopia: implications for malaria control and elimination efforts

BackgroundSchoolchildren with asymptomatic malaria infections often go undiagnosed and untreated, serving as reservoirs for infection that hamper malaria control and elimination efforts. In this context, little is known about the magnitude of asymptomatic malaria infections in apparently healthy schoolchildren in Ethiopia. This study was aimed at determining the prevalence of asymptomatic malaria infection and its associated factors in apparently healthy schoolchildren in Ethiopia.MethodsFrom September 2021 to January 2022, a school-based cross-sectional study was conducted on 994 apparently healthy schoolchildren (aged 6–15 years) selected from 21 primary schools in the Gomma district, of Jimma zone, southwestern Oromia, Ethiopia. A multi-stage sampling technique was used to select schools and participants. After allocating the total sample proportionally to each school and then to each grade, participants were selected using the lottery method from a list of student records (rosters). Finger-pricked blood samples were collected for microscopy blood film preparation and malaria rapid diagnostic test (RDT) (SD Bioline Malaria Ag Pf/Pv). Moreover, dry blood spots (DBSs) were prepared onto filter papers for quantitative real time polymerase chain reaction (qPCR) analysis.ResultsAs determined by RDT and microscopy, the prevalence of asymptomatic malaria was 2.20% and 1.51%, respectively. Using qPCR, the overall prevalence was 5.03% (50/994). Of this, Plasmodium falciparum, Plasmodium vivax and mixed infections accounted for 90%, 6% and 4%, respectively. Submicroscopic asymptomatic malaria infection was also accounted for 70% (35/50) of the overall prevalence. Household head age, nighttime outdoor activities of household heads, family history of malaria, absence of insecticide-treated nets (ITN), and presence of stagnant water around the houses are all significantly associated with asymptomatic malaria infections among schoolchildren.ConclusionsThis study found that both RDT and microscopy underestimated the prevalence of asymptomatic malaria in schoolchildren. However, qPCR was able to detect even low levels of parasitaemia and revealed a higher prevalence of asymptomatic submicroscopic malaria infections. The findings imply that schoolchildren with asymptomatic malaria infection are potential hotspot for malaria reservoir that fuels ongoing transmission. Therefore, it is imperative to include schoolchildren and schools in malaria intervention package and equally important is the adoption of more advanced and sensitive diagnostic tools, which would be crucial for successful malaria control and elimination efforts. Targeted interventions for asymptomatic malaria-infected schoolchildren can provide invaluable support to the National Malaria Control Programme in controlling and eventually eliminating the disease.

Performance and accuracy of SD Bioline malaria Ag P.f (05fk50) in relation to microscopy as the gold standard technique for malaria diagnosis

Successful malaria diagnosis is the mainstay of successful treatment, prevention and eradication of malaria infection. Apart from the gold standard technique (Microscopy), numerous diagnostic techniques perform a similar function to microscopy and in most cases tend to have varying sensitivity and specificity, especially when compared with the gold standard technique. Therefore this study aimed to determine the Performance and accuracy of SD Bioline Malaria Ag P.f (05fk50) (Rapid Diagnostic Test kit) to Gold standard (Microscopy). A total of two hundred (200) samples were collected from the consented study subjects and analyzed using RDT and Giemsa staining technique. The result revealed an overall prevalence of 132(66.0%) and 167(83.5%) respectively by RDT and Microscopy, where 115 (57.5%) were true positive, there was no significant difference between the two techniques (P> 0.05, df= 1, χ2 = 3.695). The RDT recorded a sensitivity and specificity value of 68.86% and 48.48% respectively with a positive predictive value of 87.78% and a negative predictive value of 23.53%. The RDT recorded an overall accuracy of 0.66. The Rapid Diagnostic test kit used in the present demonstrated a high level of sensitivity and positive predictive value with relatively low specificity and negative predictive value. Regular checks on the Performance and accuracy of all brands of RDT should be conducted as their perform

Unusual clinical spectra of childhood severe malaria during malaria epidemic in eastern Uganda: a prospective study

BackgroundIn sub-Saharan Africa (SSA), malaria remains a public health problem despite recent reports of declining incidence. Severe malaria is a multiorgan disease with wide-ranging clinical spectra and outcomes that have been reported to vary by age, geographical location, transmission intensity over time. There are reports of recent malaria epidemics or resurgences, but few data, if any, focus on the clinical spectrum of severe malaria during epidemics. This describes the clinical spectrum and outcomes of childhood severe malaria during the disease epidemic in Eastern Uganda.MethodsThis prospective cohort study from October 1, 2021, to September 7, 2022, was nested within the ‘Malaria Epidemiological, Pathophysiological and Intervention studies in Highly Endemic Eastern Uganda’ (TMA2016SF-1514-MEPIE Study) at Mbale Regional Referral Hospital, Uganda. Children aged 60 days to 12 years who at admission tested positive for malaria and fulfilled the clinical WHO criteria for surveillance of severe malaria were enrolled on the study. Follow-up was performed until day 28. Data were collected using a customized proforma on social demographic characteristics, clinical presentation, treatment, and outcomes. Laboratory analyses included complete blood counts, malaria RDT (SD BIOLINE Malaria Ag P.f/Pan, Ref. 05FK60-40-1) and blood slide, lactate, glucose, blood gases and electrolytes. In addition, urinalysis using dipsticks (Multistix® 10 SG, SIEMENS, Ref.2300) at the bedside was done. Data were analysed using STATA V15.0. The study had prior ethical approval.ResultsA total of 300 participants were recruited. The median age was 4.6 years, mean of 57.2 months and IQR of 44.5 months. Many children, 164/300 (54.7%) were under 5 years, and 171/300 (57.0%) were males. The common clinical features were prostration 236/300 (78.7%), jaundice in 205/300 (68.3%), severe malarial anaemia in 158/300 (52.7%), black water fever 158/300 (52.7%) and multiple convulsions 51/300 (17.0%), impaired consciousness 50/300(16.0%), acidosis 41/300(13.7%), respiratory distress 26/300(6.7%) and coma in 18/300(6.0%). Prolonged hospitalization was found in 56/251 (22.3%) and was associated with acidosis, P = 0.041. The overall mortality was 19/300 (6.3%). Day 28 follow-up was achieved in 247/300 (82.3%).ConclusionDuring the malaria epidemic in Eastern Uganda, severe malaria affected much older children and the spectrum had more of prostration, jaundice severe malarial anaemia, black water fever and multiple convulsions with less of earlier reported respiratory distress and cerebral malaria.

Diagnostic performance of NxTek™ Eliminate Malaria-Pf test for the detection of Plasmodium falciparum in school children with asymptomatic malaria

BackgroundOne of the major roadblocks to the falciparum malaria elimination programme is the presence of a portion of the population, such as school children, with asymptomatic malaria infection. Targeting such reservoirs of infections is critical to interrupting transmission and enhancing elimination efforts. The NxTek™ Eliminate Malaria Pf test is a highly sensitive rapid diagnostic test (hsRDT) for the detection of HRP-2. However, knowledge gaps exist in Ethiopia on the diagnostic performance of hsRDT for the detection of Plasmodium falciparum in school children with asymptomatic malaria.MethodsA school-based cross-sectional study was conducted from September 2021 to January 2022 on 994 healthy school children (aged 6–15 years). Finger-pricked whole blood samples were collected for microscopy, hsRDT, conventional RDT (cRDT or SD Bioline Malaria Ag Pf/P.v), and QuantStudio™ 3 Real—Time PCR system (qPCR). The hsRDT was compared to cRDT and microscopy. qPCR and microscopy were used as reference methods.ResultsThe prevalence of Plasmodium falciparum was 1.51%, 2.2%. 2.2% and 4.52%, by microscopy, hsRDT, cRDT and qPCR, respectively. Using qPCR as reference, the sensitivity of hsRDT was higher (48.89%) than the microscopy (33.3%), and showed 100% specificity and a positive predictive value (PPV). Microscopy showed similar specificity and PPV as hsRDT. Using microscopy as a reference, the diagnostic perforrmances of both hsRDT and cRDT were similar. Both RDTs demonstrated identical diagnostic performances in both comparison methods.ConclusionshsRDT has the same diagnostic performance as cRDT but improved diagnostic characteristics than microscopy for detection of P. falciparum in school children with asymptomatic malaria. It can be a useful tool for the national malaria elimination plan of Ethiopia.

Evaluation of Four Malaria Rapid Diagnostic Test Kits Used at the Enyiresi Government Hospital in the Eastern Region of Ghana

Microscopic identification of Plasmodium spp. is the gold standard for malaria diagnosis. However, malaria rapid diagnostic test kits are also available for prompt diagnosis. This study evaluated four routinely used malaria rapid diagnostic test kits at the Enyiresi Government Hospital in the Eastern Region of Ghana. This cross-sectional study was conducted among 238 patients suspected of malaria. Venous blood samples were collected to identify Plasmodium falciparum using microscopic techniques. Further, the performances of four malaria rapid diagnostic test kits, First Response Malaria Ag Pf, Carestart Malaria Pf, SD Bioline Ag Pf, and ABON Malaria Pf, were evaluated using the results from the microscopy as the standard reference. As confirmed by microscopy, 65.5% (156/238) of the patients have falciparum malaria. All malaria rapid diagnostic test kits had sensitivities and specificities over 75% compared to microscopy results as the reference standard. However, the SD Bioline Ag Pf kit recorded the highest agreement with the microscopy ( Cohe n ’ s kappa = 0.879 ). All the malaria rapid diagnostic test kits performed quite well and can be used in emergencies. However, results from these kits need to be confirmed by microscopy.

Performance analysis of polymerase chain reaction in relation to rapid diagnostic test (RDT) kit (SD bio line malaria ag p.f (05fk50)) for malaria diagnosis

Malaria control and its elimination heavenly depend on successful and reliable diagnosis using recommended diagnostic techniques. These available techniques often have certain peculiarities and mode applications, thus making them have different levels of performance and accuracy. Therefore the aim of this study was to evaluate the performance of PCR in relation to Rapid Diagnostic Test Kit (SD Bio line Malaria Ag P.f (05fk50)) in malaria diagnosis. A total of 200 blood samples were collected from the consented study subjects using the vein puncture technique and analysed using PCR and RDTs. Plasmodium falcifarum’s DNA was extracted using Quick-DNA™ Miniprep Plus Kit with catalog number D4069. 18SrRNA gene of Plasmodium falciparum from chromosome 13 was amplified using the two primers. For the RDTs technique, the SD Bio line Malaria Ag P.f (05fk50) test kit was used. Malaria prevalence of 106(53.0%) and 132(66.0%) were recorded using PCR and RDTs respectively. The PCR demonstrates an overall accuracy of 0.53 with sensitivity and specificity values of 56.06 and 52.94% respectively. The negative and positive predictive values were 69.81 and 38.30% respectively. PCR demonstrated a good level of performance and is therefore recommended as an effective diagnostic tool for malaria, especially in patients where the parasite density/parasitaemia level is very low.

DNA recovery from used malaria RDT to detect Plasmodium species and to assess Plasmodium falciparum genetic diversity: a pilot study in Madagascar

BackgroundRapid diagnostic tests (RDT) are widely used for malaria diagnosis in Madagascar, where Plasmodium falciparum is the predominant species. Molecular diagnosis is essential for malaria surveillance, but requires additional blood samples for DNA extraction. Used RDTs is an attractive alternative that can be used as a source of DNA. Plasmodium falciparum genetic diversity and multiplicity of infection, usually determined by the genotyping of polymorphic regions of merozoite surface proteins 1 and 2 genes (msp1, msp2), and the repeated region RII of the glutamate-rich protein gene (glurp) have been associated with malaria transmission levels and subsequently with the impact of the deployed control strategies.Thus, the study aims to use RDT as DNA source to detect Plasmodium species, to characterize Plasmodium falciparum genetic diversity and determine the multiplicity of infection.MethodsA pilot study was conducted in two sites with different epidemiological patterns: Ankazomborona (low transmission area) and Matanga (high transmission area). On May 2018, used RDT (SD BIOLINE Malaria Ag P.f/Pan, 05FK63) were collected as DNA source. Plasmodium DNA was extracted by simple elution with nuclease free water. Nested-PCR were performed to confirm Plasmodium species and to analyse P. falciparum msp1, msp2 and glurp genes polymorphisms.ResultsAmongst the 170 obtained samples (N = 74 from Ankazomborona and N = 96 from Matanga), Plasmodium positivity rate was 23.5% (40/170) [95% CI 17.5–30.8%] by nested-PCR with 92.2% (37/40) positive to P. falciparum, 5% (2/40) to Plasmodium vivax and 2.5% (1/40) to P. falciparum/P. vivax mixed infection. Results showed high polymorphisms in P. falciparum msp1, msp2 and glurp genes. Multiple infection rate was 28.6% [95% CI 12.2–52.3%]. The mean of MOI was 1.79 ± 0.74.ConclusionThis pilot study highlighted that malaria diagnosis and molecular analysis are possible by using used malaria RDT. A large-scale study needs to be conducted to assess more comprehensively malaria parasites transmission levels and provide new data for guiding the implementation of local strategies for malaria control and elimination.Trial registration Retrospectively registered

Diagnostic performance and comparison of ultrasensitive and conventional rapid diagnostic test, thick blood smear and quantitative PCR for detection of low-density Plasmodium falciparum infections during a controlled human malaria infection study in Equatorial Guinea

BackgroundProgress towards malaria elimination has stagnated, partly because infections persisting at low parasite densities comprise a large reservoir contributing to ongoing malaria transmission and are difficult to detect. This study compared the performance of an ultrasensitive rapid diagnostic test (uRDT) designed to detect low density infections to a conventional RDT (cRDT), expert microscopy using Giemsa-stained thick blood smears (TBS), and quantitative polymerase chain reaction (qPCR) during a controlled human malaria infection (CHMI) study conducted in malaria exposed adults (NCT03590340).MethodsBlood samples were collected from healthy Equatoguineans aged 18–35 years beginning on day 8 after CHMI with 3.2 × 103 cryopreserved, infectious Plasmodium falciparum sporozoites (PfSPZ Challenge, strain NF54) administered by direct venous inoculation. qPCR (18s ribosomal DNA), uRDT (Alere™ Malaria Ag P.f.), cRDT [Carestart Malaria Pf/PAN (PfHRP2/pLDH)], and TBS were performed daily until the volunteer became TBS positive and treatment was administered. qPCR was the reference for the presence of Plasmodium falciparum parasites.Results279 samples were collected from 24 participants; 123 were positive by qPCR. TBS detected 24/123 (19.5% sensitivity [95% CI 13.1–27.8%]), uRDT 21/123 (17.1% sensitivity [95% CI 11.1–25.1%]), cRDT 10/123 (8.1% sensitivity [95% CI 4.2–14.8%]); all were 100% specific and did not detect any positive samples not detected by qPCR. TBS and uRDT were more sensitive than cRDT (TBS vs. cRDT p = 0.015; uRDT vs. cRDT p = 0.053), detecting parasitaemias as low as 3.7 parasites/µL (p/µL) (TBS and uRDT) compared to 5.6 p/µL (cRDT) based on TBS density measurements. TBS, uRDT and cRDT did not detect any of the 70/123 samples positive by qPCR below 5.86 p/µL, the qPCR density corresponding to 3.7 p/µL by TBS. The median prepatent periods in days (ranges) were 14.5 (10–20), 18.0 (15–28), 18.0 (15–20) and 18.0 (16–24) for qPCR, TBS, uRDT and cRDT, respectively; qPCR detected parasitaemia significantly earlier (3.5 days) than the other tests.ConclusionsTBS and uRDT had similar sensitivities, both were more sensitive than cRDT, and neither matched qPCR for detecting low density parasitaemia. uRDT could be considered an alternative to TBS in selected applications, such as CHMI or field diagnosis, where qualitative, dichotomous results for malaria infection might be sufficient.

Performance and utility of more highly sensitive malaria rapid diagnostic tests

BackgroundA new more highly sensitive rapid diagnostic test (HS-RDT) for Plasmodium falciparum malaria (Alere™/Abbott Malaria Ag P.f RDT [05FK140], now called NxTek™ Eliminate Malaria Ag Pf) was launched in 2017. The test has already been used in many research studies in a wide range of geographies and use cases.MethodsIn this study, we collate all published and available unpublished studies that use the HS-RDT and assess its performance in (i) prevalence surveys, (ii) clinical diagnosis, (iii) screening pregnant women, and (iv) active case detection. Two individual-level data sets from asymptomatic populations are used to fit logistic regression models to estimate the probability of HS-RDT positivity based on histidine-rich protein 2 (HRP2) concentration and parasite density. The performance of the HS-RDT in prevalence surveys is estimated by calculating the sensitivity and positive proportion in comparison to polymerase chain reaction (PCR) and conventional malaria RDTs.ResultsWe find that across 18 studies, in prevalence surveys, the mean sensitivity of the HS-RDT is estimated to be 56.1% (95% confidence interval [CI] 46.9–65.4%) compared to 44.3% (95% CI 32.6–56.0%) for a conventional RDT (co-RDT) when using nucleic acid amplification techniques as the reference standard. In studies where prevalence was estimated using both the HS-RDT and a co-RDT, we found that prevalence was on average 46% higher using a HS-RDT compared to a co-RDT. For use in clinical diagnosis and screening pregnant women, the HS-RDT was not significantly more sensitive than a co-RDT.ConclusionsOverall, the evidence presented here suggests that the HS-RDT is more sensitive in asymptomatic populations and could provide a marginal improvement in clinical diagnosis and screening pregnant women. Although the HS-RDT has limited temperature stability and shelf-life claims compared to co-RDTs, there is no evidence to suggest, given this test has the same cost as current RDTs, it would have any negative impacts in terms of malaria misdiagnosis if it were widely used in all four population groups explored here.