Parasitemia Density Research Articles

LLIN Evaluation in Uganda Project (LLINEUP)–effects of a vector control trial on Plasmodium infection prevalence and genotypic markers of insecticide resistance in Anopheles vectors from 48 districts of Uganda

Pyrethroid bednets treated with the synergist piperonyl butoxide (PBO) offer the possibility of improved vector control in mosquito populations with metabolic resistance. In 2017–2019, we conducted a large-scale, cluster-randomised trial (LLINEUP) to evaluate long-lasting insecticidal nets (LLINs) treated with a pyrethroid insecticide plus PBO (PBO LLINs), as compared to conventional, pyrethroid-only LLINs across 104 health sub-districts (HSDs) in Uganda. In LLINEUP, and similar trials in Tanzania, PBO LLINs were found to provide greater protection against malaria than conventional LLINs, reducing parasitaemia and vector density. In the LLINEUP trial, we conducted cross-sectional household entomological surveys at baseline and then every 6 months for two years, which we use here to investigate longitudinal changes in mosquito infection rate and genetic markers of resistance. Overall, 5395 female Anopheles mosquitoes were collected from 5046 households. The proportion of mosquitoes infected (PCR-positive) with Plasmodium falciparum did not change significantly over time, while infection with non-falciparum malaria decreased in An. gambiae s.s., but not An. funestus. The frequency of genetic markers associated with pyrethroid resistance increased significantly over time, but the rate of change was not different between the two LLIN types. The knock-down resistance (kdr) mutation Vgsc-995S declined over time as Vgsc-995F, the alternative resistance mutation at this codon, increased. Vgsc-995F appears to be spreading into Uganda. Distribution of LLINs in Uganda was previously found to be associated with reductions in parasite prevalence and vector density, but here we show that the proportion of infective mosquitoes remained stable across both PBO and non-PBO LLINs, suggesting that the potential for transmission persisted. The increased frequency of markers of pyrethroid resistance indicates that LLIN distribution favoured the evolution of resistance within local vectors and highlights the potential benefits of resistance management strategies.Trial registration: This study is registered with ISRCTN, ISRCTN17516395. Registered 14 February 2017, http://www.isrctn.com/ISRCTN17516395.

Antiplasmodial Properties of Ethanol Stem-Bark Extract of <i>Newbouldia Laevis</i> (P. Beauv) Seem in <i>P. Berghei</i> Infected Mice

Background: Despite substantial improvement in the management of malaria infection over the last centuries, it remains a significant public threat especially to those in the tropical and subtropical African regions due to the emergence of drug-resistant P. falciparum strains, delayed diagnosis, high cost as well as contraindications of some available antimalarial medications. Hence, the need for necessary measures in terms of alternative therapeutic approaches to counter this threat is of utmost importance. The present study was aimed at determining the antimalarial potential of ethanol stem-bark extract of Newbouldia laevis in P. berghei (NK65) infected mice. 
 Methodology: The antimalarial activity of Newbouldia laevis stem-bark at 250, 500 and 1,000 mg/kg was investigated in mice infected with 1 x 107 parasitized erythrocytes using three experimental animal models: Peter's 4-day suppressive, curative and prophylactic models. Phytochemical screening of the stem bark was also conducted.
 Results: The extract at all tested doses of 250, 500 and 1000 mg/ kg showed significant (p<0.01) and dose-dependent reductions in the parasitemia levels of the treated rats with percentage chemosuppresion of 90.7, 91.8 and 94% respectively in the Peters 4-day suppressive test. There were also significant (p<0.01) dose- dependent reductions in parasitemia density of the treated rats at all doses of 250, 500 and 1000 mg/kg in the curative and prophylactic studies compared to the distilled water group. Phytochemical screening revealed the presence of carbohydrates, tannins, alkaloids, flavonoids, saponins, terpenoids, cardiac glycosides, steroids and anthraquinones in the crude extract.
 Conclusion: The results suggest that ethanol stem-bark extract of Newbouldia laevis possesses antimalarial activity and this justifies the traditional use of the stem-bark of the plant in antimalarial herbal remedy.

Malaria Infection in Patients with Sickle Cell Disease in Nigeria: Association with Markers of Hyposplenism.

Malaria is considered an important cause of morbidity and mortality among people living with sickle cell disease (SCD). This has partly been attributed to the loss of splenic function that occurs early in the disease process. We conducted a cross-sectional study and determined the frequency of malaria infection among SCD patients and explored the association with spleen's presence on ultrasonography and spleen function assessed using the frequency of Howell-Jolly bodies (HJBs). A total of 395 participants consisting of 119 acutely-ill SCD patients, 168 steady-state SCD controls, and 108 healthy non-SCD controls were studied. The prevalence of Plasmodium falciparum parasitemia was 51.3% in acutely-ill SCD patients, 31.7% in steady-state SCD controls, and 11.0% in the healthy non-SCD controls; however, the mean parasite density was significantly higher in the non-SCD controls compared to both SCD groups (p = 0.0001). Among the acutely-ill SCD patients, the prevalence of clinical malaria and severe malaria anemia were highest in children <5 years of age. The prevalence of parasitemia (p = 0.540) and parasite density (p = 0.975) showed no association with spleen presence or absence on ultrasonography. Similarly, the frequency of HJB red cells was not associated with the presence of parasitemia (p = 0.183). Our study highlights the frequency and role of malaria infection in acutely-ill SCD patients, especially in those younger than five years. Although we have found no evidence of an increased risk of malaria parasitemia or parasite density with markers of hyposplenism, the role played by an underlying immunity to malaria among SCD patients in malaria-endemic region is not clear and needs further studies.

Prophylactic effects of probiotic bacterium Latilactobacillus sakei on haematological parameters and cytokine profile of mice infected with Plasmodium berghei ANKA during early malaria infection

Malaria is a deadly parasitic disease caused a by protozoan parasite of the genus plasmodium. The challenges facing by chemotherapy and vector control couple with the lack of vaccine against malaria necessitate an urgent need for the development of alternative treatment regimens to combat this disease. One possible antimalarial treatment regimen is the use of probiotic bacteria as dietary supplements. Traditionally fermented milk is a rich source of probiotic bacteria that up to date, very few studies have been carried out on their immunoprotective effects against early malaria infection in mice. This study sought to assess the prophylactic activities of a probiotic bacterium Latilactobacillus sakei on malaria and inflammation in Plasmodium berghei infected mice. The probiotic bacterium was isolated from the Fulani's traditionally fermented milk and identified using the sequencing of the 16S r RNA gene. The repository activity of L. sakei on malaria was assessed using the method described by Peters with slight modification. Eighty-four BALB/c mice were randomly divided into two sets of seven groups of six mice each. One set received orally different doses of L. sakei Chloroquine and Sulfadoxine/Pyrimethamine for seven days before infection while the other set received for fourteen days before infection with 0.1 mL of 107Plasmodium berghei. Parasitaemia density, haematological parameters and inflammatory cytokines profile were evaluated. Data were presented as Mean ± SEM and analysed using SPSS version 20.0. The results of this study revealed that L. sakei significantly (p < 0.05) reduced in dose dependent manner parasite load, body weight loss and reduction of body temperature in all the treated mice when compare to untreated mice. Leukocytopenia, thrombocytosis and inflammation were also found to be significantly (p < 0.05) prevented in treated mice as compared to untreated mice.This study suggested that L sakei possesses immunomodulation and protective effects on early malaria infection in Plasmodium berghei mice.

Effects of uncomplicated malaria parasitaemia on selected haematological parameters and phagocytes of children living in Port Harcourt, Southern Nigeria

This cross-sectional and case control study evaluated the effects of malaria parasites on selected haematological parameters of children living in Port Harcourt, Nigeria. A total of 352 participants were randomly recruited and their blood samples collected. Malaria diagnosis and estimation of haematological parameters were determined using standard parasitological and haematological methods respectively. Sociodemographics of participants showed that 109 (31%) of female children and 106 (30%) of male children were infected with malaria parasites. Overall prevalence of Plasmodium falciparum found was 215(61%). The study found a statistically significant difference in the mean values of packed cell volume (PCV), haemoglobin concentration (Hb), and white blood cell count (WBC) of Plasmodium parasitized children compared with their matched controls: PCV(34.83±2.76% versus 36.06±1.41%; P=0.001); Hb(11.58±0.92g/dL versus 11.98±0.46g/dL; P=0.001); WBC (8.96±4.56(x109/L) versus 7.33±1.39(x109/L); P=0.001).While the mean values of lymphocyte counts were relatively reduced in malaria infected children than their control participants (41.66±13.57(x109/L) versus 42.95±8.36(x109/L); P=0.27). A weak relationship was found to exist between density of parasitaemia and ages of children infected with malaria parasites (R2=0.0093; P=0.1584). Though more children had low parasitaemia (1-999 parasites/μL), followed with high parasitaemia (&gt;10,000 parasites/μL), while few had moderate parasitaemia (1000-9999 parasites/μL). There was no case of complication with respect to WHO standard which described complicated or severe anaemia in malaria as haemoglobin (Hb) of &lt; 5g/dl or packed cell volume (PCV) of &lt; 15% with parasitemia of &gt; 250,000 parasites/μL. Malaria parasites affect outcomes of some haematological parameters. We recommend that all febrile children in our study area should be tested for malaria parasites in conjunction with estimation of their full blood count for effective malaria diagnosis and treatment particularly in sub patent cases.

Association between hemoglobin variants and laboratory outcomes in patients infected with P. falciparum from South West Uganda.

We assess the relationship between various hemoglobin variants and some hematological parameters packed cell volume, white blood cells (PCV, WBC) and parasitemia level of patients with malaria in the southwestern, Uganda. Patient were enrolled by rapid diagnostic tests (RDTs), confirmed by microscopy, and laboratory outcomes were determined. Patients positive for malaria RDTs were 155, microscopic-confirmed P. falciparum parasites were 95(61.29%) having hemoglobin variants HbAA andHbAS; 75(78.95%) and13(13.68%), respectively. The laboratory outcomes showed mean, PCV(32.19±4.83), WBC(5831.66±2888.29) and P. falciparum parasitaemia density (32,605.45±14031), while the hemoglobin variants mean values AA(39,008.85±31,261.56), AC(15908±10173.48), AS(16,561.46±15,380.93), SC(30,524±0.000) and SS(1652±0.000) were significantly different from the total population (34,321.5±21,924.26) parasite-density. Patients with hemoglobin variants HbAA had asignificantly higher parasite-carrying capacity and PCV levels.

Variability in white blood cell count during uncomplicated malaria and implications for parasite density estimation: a WorldWide Antimalarial Resistance Network individual patient data meta-analysis

BackgroundThe World Health Organization (WHO) recommends that when peripheral malarial parasitaemia is quantified by thick film microscopy, an actual white blood cell (WBC) count from a concurrently collected blood sample is used in calculations. However, in resource-limited settings an assumed WBC count is often used instead. The aim of this study was to describe the variability in WBC count during acute uncomplicated malaria, and estimate the impact of using an assumed value of WBC on estimates of parasite density and clearance.MethodsUncomplicated malaria drug efficacy studies that measured WBC count were selected from the WorldWide Antimalarial Resistance Network data repository for an individual patient data meta-analysis of WBC counts. Regression models with random intercepts for study-site were used to assess WBC count variability at presentation and during follow-up. Inflation factors for parasitaemia density, and clearance estimates were calculated for methods using assumed WBC counts (8000 cells/µL and age-stratified values) using estimates derived from the measured WBC value as reference.ResultsEighty-four studies enrolling 27,656 patients with clinically uncomplicated malaria were included. Geometric mean WBC counts (× 1000 cells/µL) in age groups < 1, 1–4, 5–14 and ≥ 15 years were 10.5, 8.3, 7.1, 5.7 and 7.5, 7.0, 6.5, 6.0 for individuals with falciparum (n = 24,978) and vivax (n = 2678) malaria, respectively. At presentation, higher WBC counts were seen among patients with higher parasitaemia, severe anaemia and, for individuals with vivax malaria, in regions with shorter regional relapse periodicity. Among falciparum malaria patients, using an assumed WBC count of 8000 cells/µL resulted in parasite density underestimation by a median (IQR) of 26% (4–41%) in infants < 1 year old but an overestimation by 50% (16–91%) in adults aged ≥ 15 years. Use of age-stratified assumed WBC values removed systematic bias but did not improve precision of parasitaemia estimation. Imprecision of parasite clearance estimates was only affected by the within-patient WBC variability over time, and remained < 10% for 79% of patients.ConclusionsUsing an assumed WBC value for parasite density estimation from a thick smear may lead to underdiagnosis of hyperparasitaemia and could adversely affect clinical management; but does not result in clinically consequential inaccuracies in the estimation of the prevalence of prolonged parasite clearance and artemisinin resistance.

Evaluation of the Relationship among Different Haemoglobin Genotypes, Calcium, and Membrane Potential in Patients with Malaria in FMC, Umuahia

Malaria is still a major contributor to the high rate of global infectious disease-related mortality and morbidity particularly in Nigeria. The aim of this study is to assess the relationship between various Hemoglobin Genotypes, Calcium, and Membrane Potential in malaria patients. Retrospective analysis of the results of the distribution of Malaria parasitemia among suspected cases of malaria, various Haemoglobin genotypes, Calcium and Membrane Potential were conducted in Federal Medical Centre (FMC) Umuahia, Abia State. Two hundred cases were examined by Giemsa staining method using thick film. Haemoglobin genotype determination was performed by Cellulose acetate electrophoresis. Obtained data were analyzed using One-Way ANOVA. Results: One hundred and seventy (85.0%) were positive for Malaria parasite. The prevalence was 92(54.1%) and 78(46.0%) for females and males respectively and at p&lt;0.05, the result obtained from the statistics is considered significant. There are high prevalence of parasitemia in AA, 80(40.0%), with genotype SS recording the least with 30(15%). The age group 27-35 years had the highest occurrence of parasitemia with (44.1%) while the least was obtained in the age range 45-53 years with (2.4%). It was observed that the density of Malaria parasitemia was highest in the age group 27-35 years meaning that parasite density decreases with increasing age and the Haemoglobin genotype AA had the highest Malaria density. Also, the serum Calcium and Membrane Potential were significantly reduced in Sickle cell disease (HbSS) when compared to the HbAA and HbAS individuals. This signifies a low energy level in Sickle cell patients that can result in oxidative stress. This may probably indicate that serum Calcium and Membrane Potential are significantly reduced in Sickle cell patients compared with other Haemoglobin genotypes with Malaria.

Intermittent preventive treatment with Sulphadoxine-Pyrimethamine (IPTp-SP) is associated with protection against sub-microscopic P. falciparum infection in pregnant women during the low transmission dry season in southwestern Cameroon: A Semi - longitudinal study.

The current guidelines for malaria prevention and control during pregnancy in Africa is predicated on the prevention of infection and/or disease through intermittent preventive treatment in pregnancy (IPTp), insecticide-treated nets (ITNs) and effective malaria case diagnosis and management. Concerns that increasing SP resistance in some areas of SSA may have compromised IPTp-SP efficacy prompted this contemporaneous study, designed to assess the prevalence and risk factors of sub-microscopic infection in parturient women during the low transmission season in Mutengene, a rapidly growing semi-urban area in Southwest Region, Cameroon. Pregnant women originally reporting for the establishment of antenatal clinic care during the dry season were followed-up to term and their pregnancy outcomes recorded. About 2 ml of venous blood was collected for malaria diagnosis using PfHRP2/pLDH malaria rapid diagnostic kit and light microscopy. DNA was extracted from dried blood spots by the Chelex-100 method and the Plasmodium falciparum status detected by nested PCR amplification of the 18SrRNA gene using specific predesigned primers. Of the 300 women enrolled, the proportion of malaria parasite infected as determined by microscopy, RDT and PCR was 12.9%, 16.4% and 29.4% respectively, with 39.9% overall infected with P. falciparum by microscopy and/or RDT and/or PCR and a very low-density infection, averaging 271 parasites per microliter of blood. About 25.0% (68/272) of women who were negative by microscopy were positive by PCR (submicroscopic P. falciparum infection), with primigravidae and IPTp-SP non usage identified as independent risk factors for submicroscopic P. falciparum parasitaemia while fever history (aOR = 4.83, 95% CI = 1.28-18.22, p = 0.020) was associated with risk of malaria parasite infection overall. IPTp-SP use (p = 0.007) and dosage (p = 0.005) significantly influenced whether or not the participant will be malaria parasite negative or carry submicroscopic or microscopic infection. Although Infant birthweight and APGAR score were independent of the mother's P. falciparum infection and submicroscopic status, infant's birthweight varied with the gravidity status (p = 0.001) of the mother, with significantly lower birthweight neonates born to primigravidae compared to secundigravidae (p = 0.001) and multigravidae (p = 0.003). Even in holo-endemic dry season, there exists a large proportion of pregnant women with very low density parasitaemia. IPTp-SP seems to be relevant in controlling submicroscopic P. falciparum infections, which remains common in pregnant women, and are hard to diagnose, with potentially deleterious consequences for maternal and fetal health. Future studies should be carried out in hyperendemic malaria foci where the parasitemia levels are substantially higher in order to confirm the efficacy of IPTp-SP.

Predicting Plasmodium falciparum infection status in blood using a multiplexed bead-based antigen detection assay and machine learning approaches.

Plasmodium blood-stage infections can be identified by assaying for protein products expressed by the parasites. While the binary result of an antigen test is sufficient for a clinical result, greater nuance can be gathered for malaria infection status based on quantitative and sensitive detection of Plasmodium antigens and machine learning analytical approaches. Three independent malaria studies performed in Angola and Haiti enrolled persons at health facilities and collected a blood sample. Presence and parasite density of P. falciparum infection was determined by microscopy for a study in Angola in 2015 (n = 193), by qRT-PCR for a 2016 study in Angola (n = 208), and by qPCR for a 2012-2013 Haiti study (n = 425). All samples also had bead-based detection and quantification of three Plasmodium antigens: pAldolase, pLDH, and HRP2. Decision trees and principal component analysis (PCA) were conducted in attempt to categorize P. falciparum parasitemia density status based on continuous antigen concentrations. Conditional inference trees were trained using the known P. falciparum infection status and corresponding antigen concentrations, and PCR infection status was predicted with accuracies ranging from 73-96%, while level of parasite density was predicted with accuracies ranging from 59-72%. Multiple decision nodes were created for both pAldolase and HRP2 antigens. For all datasets, dichotomous infectious status was more accurately predicted when compared to categorization of different levels of parasite densities. PCA was able to account for a high level of variance (>80%), and distinct clustering was found in both dichotomous and categorical infection status. This pilot study offers a proof-of-principle of the utility of machine learning approaches to assess P. falciparum infection status based on continuous concentrations of multiple Plasmodium antigens.

Phase 3 Evaluation of an Innovative Simple Molecular Test for the Diagnosis of Malaria and Follow-Up of Treatment Efficacy in Pregnant Women in Sub-Saharan Africa (Preg-Diagmal).

The malaria parasite Plasmodium falciparum (Pf) can sequester in the placenta resulting in low density of peripheral parasitemia and consequently in false negative malaria diagnosis (by microscopy) in pregnant women. Moreover, the use of rapid diagnostic tests (RDTs) in diagnostic strategies, including those for the detection of a malaria infection during pregnancy, is constrained by either persistent malaria antigen (histidine-rich protein 2; HRP2) after successful treatment, leading to false positive test results, or by false negative results as previously mentioned due to parasite sequestration (which is further exacerbated due to the low limited of detection [LoD] of conventional RDTs) or to HRP2 deletion. Recently, a direct blood polymerase chain reaction combined with a nucleic acid lateral flow immunoassay (dbPCR-NALFIA) has been developed, which circumvents these challenges and has demonstrated its diagnostic potential in phase 1 and 2 studies. The PREG-DIAGMAL trial presented in this manuscript will assess the diagnostic performance of dbPCR-NALFIA for the diagnostic of malaria in pregnant women and its potential to monitor treatment efficacy in these subjects. The work is ancillary embedded in an ongoing EDCTP funded trial, the PyraPreg project (PACTR202011812241529) in which the safety and efficacy of a newly registered Artemisinin-Based Combination (Pyronaridine-Artesunate) is being evaluated in pregnant women. This is a Phase 3 diagnostic evaluation conducted in 2 African countries: Democratic Republic of the Congo (DRC) and Burkina Faso. Pregnant women fulfilling the inclusion criteria of the PyraPreg study will be also invited to participate in the PREG-DIAGMAL study. Diagnostic accuracy will be assessed following the WHO/TDR guidelines for the evaluation of diagnostics and reported according to STARD principles. Due to the lack of a 100% specific and sensitive standard diagnostic test for malaria, the sensitivity and specificity of the new test will be compared to the available diagnostic practice in place at the selected settings (microscopy and/or RDT) and to quantitative PCR as the reference test. This phase 3 diagnostic study is designed towards the evaluation of the performance of a new diagnostic tool for the screening of malaria and the monitoring of treatment in pregnant women under real conditions life. If successful, the dbPCR-NALFIA could be a valuable tool to add to the diagnostic arsenal for malaria, in particular during pregnancy. Trial registration: Pan African Clinical Trial Registry database (PACTR202203780981413). Registered on 17 March 2022.

Does Hyperuricemia in Falciparum Malaria Infected Children Explains the Etiology of Burkitt’s Lymphoma?

Falciparum malaria still represents the big obstacle to communities in Sub-Sahara African countries and more concentrated efforts against COVID-19 pandemic, may influence the lives of millions of children in that malaria-endemic area. Hyperuricemia associated with plasmodium falciparum infection reflects the density of parasitemia and it may lead to kidney injury, resulting in low vitamin D production. Furthermore, hyperuricemia leads to high levels of proinflammatory cytokines counting interferon γ-induced protein, which is invested vitamin D deficiency in the development of Burkitt’s lymphoma. Experimental research is required.

Field evaluation of the diagnostic performance of EasyScan GO: a digital malaria microscopy device based on machine-learning

BackgroundMicroscopic examination of Giemsa-stained blood films remains the reference standard for malaria parasite detection and quantification, but is undermined by difficulties in ensuring high-quality manual reading and inter-reader reliability. Automated parasite detection and quantification may address this issue.MethodsA multi-centre, observational study was conducted during 2018 and 2019 at 11 sites to assess the performance of the EasyScan Go, a microscopy device employing machine-learning-based image analysis. Sensitivity, specificity, accuracy of species detection and parasite density estimation were assessed with expert microscopy as the reference. Intra- and inter-device reliability of the device was also evaluated by comparing results from repeat reads on the same and two different devices. This study has been reported in accordance with the Standards for Reporting Diagnostic accuracy studies (STARD) checklist.ResultsIn total, 2250 Giemsa-stained blood films were prepared and read independently by expert microscopists and the EasyScan Go device. The diagnostic sensitivity of EasyScan Go was 91.1% (95% CI 88.9–92.7), and specificity 75.6% (95% CI 73.1–78.0). With good quality slides sensitivity was similar (89.1%, 95%CI 86.2–91.5), but specificity increased to 85.1% (95%CI 82.6–87.4). Sensitivity increased with parasitaemia rising from 57% at < 200 parasite/µL, to ≥ 90% at > 200–200,000 parasite/µL. Species were identified accurately in 93% of Plasmodium falciparum samples (kappa = 0.76, 95% CI 0.69–0.83), and in 92% of Plasmodium vivax samples (kappa = 0.73, 95% CI 0.66–0.80). Parasite density estimates by the EasyScan Go were within ± 25% of the microscopic reference counts in 23% of slides.ConclusionsThe performance of the EasyScan Go in parasite detection and species identification accuracy fulfil WHO-TDR Research Malaria Microscopy competence level 2 criteria. In terms of parasite quantification and false positive rate, it meets the level 4 WHO-TDR Research Malaria Microscopy criteria. All performance parameters were significantly affected by slide quality. Further software improvement is required to improve sensitivity at low parasitaemia and parasite density estimations.Trial registration ClinicalTrials.gov number NCT03512678.

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.

Liver Enzymes and Lipid Profile of Malaria Patients Before and After Antimalarial Drug Treatment at Dembia Primary Hospital and Teda Health Center, Northwest, Ethiopia.

BackgroundInfection with malaria in humans involves liver cell destruction, which alters the levels of liver enzymes and lipid profiles. A number of studies have been conducted to address the impact of malaria on liver enzymes and lipid profiles but no studies were addressed after antimalarial treatment in Ethiopia. This study is intended to fill this gap.MethodsAn observational cohort study was conducted at Dembia Primary Hospital and Teda Health Center, from June to August 2020. Eighty eight malaria infected study participants were recruited using random sampling techniques. Socio-demographic data, capillary and venous blood samples were collected. Assessment of liver enzymes and lipid profiles was done using Beckman Coulter DC-700 clinical chemistry analyzer. Data were entered using Epi-data and exported to SPSS version 20 for analysis. One way ANOVA, independent t-test, and paired t-test were used to compare the mean liver enzymes and lipid profile. p-value<0.05 was considered statistically significant.ResultsBefore anti-malaria treatment, among 88 study participants, elevated AST (87.5%), ALT (12.5%), ALP (43.2%), and TG (17.2%) and lower HDL (87.5%) and normal LDL and TC were observed. After treatment, 100% AST, ALT, HDL, and LDL and 92% ALP, 94.3% TC, and 86.4% TG levels were in the normal range. The mean level of AST and ALT increased while HDL decreased from low to higher density parasitaemia. Mean level of AST was significantly lower while ALT did not alter. HDL, LDL, and TC level were increased but statistically were insignificant (P>0.05).ConclusionMalaria could be responsible for increased liver enzymes and certain lipids while decreasing some lipid profiles. After anti-malaria treatment, these parameters were reversed to normal from 86.4% to 100%. Hence, prompt treatment is important to improve liver enzymes and lipid profile impairment during malaria infection.

Towards the use of a smartphone imaging-based tool for point-of-care detection of asymptomatic low-density malaria parasitaemia

BackgroundGlobally, there are over 200 million cases of malaria annually and over 400,000 deaths. Early and accurate detection of low-density parasitaemia and asymptomatic individuals is key to achieving the World Health Organization (WHO) 2030 sustainable development goals of reducing malaria-related deaths by 90% and eradication in 35 countries. Current rapid diagnostic tests are neither sensitive nor specific enough to detect the low parasite concentrations in the blood of asymptomatic individuals.MethodsHere, an imaging-based sensing technique, particle diffusometry (PD), is combined with loop mediated isothermal amplification (LAMP) on a smartphone-enabled device to detect low levels of parasitaemia often associated with asymptomatic malaria. After amplification, PD quantifies the Brownian motion of fluorescent nanoparticles in the solution during a 30 s video taken on the phone. The resulting diffusion coefficient is used to detect the presence of Plasmodium DNA amplicons. The coefficients of known negative samples are compared to positive samples using a one-way ANOVA post-hoc Dunnett’s test for confirmation of amplification.ResultsAs few as 3 parasite/µL of blood was detectable in 45 min without DNA extraction. Plasmodium falciparum parasites were detected from asymptomatic individuals’ whole blood samples with 89% sensitivity and 100% specificity when compared to quantitative polymerase chain reaction (qPCR).ConclusionsPD-LAMP is of value for the detection of low density parasitaemia especially in areas where trained personnel may be scarce. The demonstration of this smartphone biosensor paired with the sensitivity of LAMP provides a proof of concept to achieve widespread asymptomatic malaria testing at the point of care.

Prevalence, density and predictors of malaria parasitaemia among ill young Nigerian infants.

Introductioninfants in the first six months of life are relatively protected from malaria. Emerging reports from endemic regions however are showing increasing malaria susceptibility in this age group. This study set out to determine the prevalence, parasite density and predictive factors for malaria parasitaemia in ill young infants at the Wesley Guild Hospital (WGH), Ilesa, Nigeria.Methodsill infants aged one to six months were consecutively recruited over an 11-month period in a hospital based cross-sectional study. History of illness, sociodemographic and perinatal history were obtained; clinical examination and results of venous blood for thick and thin film malaria parasite examinations were recorded and analyzed.Resultsthe mean (SD) age of the 350 infants was 3.4 (1.6) months with male: female (M: F) of 1.2: 1. The prevalence of malaria parasitaemia (all plasmodium falciparum) was 19.1% while parasite density ranged from 24.0 to 400,000 parasites/µl, median (IQR) 900 (250-4,588)/µl. Sixteen (4.6%) had heavy malaria parasitaemia (>5000/µl). Low social class (OR=2.457; 95%CI 1.404-4.300; p=0.002), suboptimal antenatal care (OR=2.226; 95%CI 1.096-4.522; p=0.027), low birth weight infants (OR=4.818; 95%CI 2.317-10.018; p=<0.001) and injudicious use of haematinics (OR=3.192; 95%CI1.731-5.886; p=<0.001) were predictors of malaria parasitaemia among the infants.Conclusionone-in-five ill young infants had malaria parasitaemia with heavy parasitaemia in 23.8% of infected infants. Malaria parasitaemia was associated with modifiable factors, high index of suspicion in endemic region and optimal maternal and child care services may assist to reduce the burden of malaria in this age group.

Pretreatment gametocyte carriage in symptomatic patients with Plasmodium falciparum and Plasmodium vivax infections on the Thai-Myanmar border.

One hundred and twenty-six blood samples were collected from patients with signs and symptoms of malaria who attended malaria clinics. Malaria positive cases detected by microscopic examination were confirmed by species-specific nested-PCR in 97 (29 and 68 samples for P. falciparum and P. vivax, respectively). The proportion of P. vivax and P. falciparum-infected samples was 70.1: 29.9%. The density in P. falciparum positive samples [median (95%CI): 10,340 (5280-19,200) μ/l] was significantly higher than P. vivax positive samples [4508 (3240-6120) μ/l]. Sixteen out of twenty-nine (55.2%) and 36 out of 68 (52.9%) P. falciparum- and P. vivax-infected samples, respectively, were gametocyte-positive. Gametocyte density in the P. falciparum-infected[124 (69-253) /μl] was significantly higher than that of the P. vivax-infected [54 (45-70)/μl] samples. A significant correlation between gametocyte density and pretreatment parasitemia was only detected in P. falciparum-infected, but not P. vivax-infected samples. The observed high prevalence rates of pretreatment gametocyte carriage of both malaria species, which serves as a large malaria reservoir, particularly in P. falciparum infection, could have a significant impact on malaria control in the endemic populations.

Rapid diagnostic tests for Plasmodium vivax malaria in endemic countries.

Rapid diagnostic tests for Plasmodium vivax malaria in endemic countries.

Cord Malaria Infection, Complement Activation, Oxidative Stress, Gestational Age, and Birth Weight, Characterized by High Plasmodium falciparum Prevalence in Bamenda, Cameroon.

Background It is unknown whether the presence of Plasmodium falciparum malaria parasites in umbilical cord blood denotes activation of complement and oxidative stress to affect the duration of pregnancy and birth weight. Methods In a cross-sectional study conducted from January to April 2019 in Bamenda, Cameroon, cord blood samples were collected from 300 women at delivery. Parasitaemia was determined microscopically. Babies' weight and age of gestation were recorded. Plasma levels of complement and oxidative stress were measured by specific tests. Results Cord blood malaria prevalence was 21.33%. Babies with an infected cord showed a low birth weight and gestation age than those with uninfected cords. More babies with infected cords had LBW (6.25%) compared to the counterparts (5.50%). The levels of parasitaemia and the babies' weight showed a weak positive correlation. The prevalence of preterm and postterm birth was 4.33% and 24.33% respectively, with a weak negative correlation between the age of gestation and the umbilical cord parasitaemia. There was correlation between cord parasitaemia and levels of complement haemolytic activity titter (CH50) and specific classical pathway activity (CPA) in cord blood. CH50 and CPA levels, however, were significantly higher in infected cord blood samples, compared with uninfected cord blood samples. CH50 showed a negative correlation with the birth weight and gestational age in infected cord blood samples. The levels of total oxidative stress (TOS) and total antioxidant defense were significantly lower in infected cord blood than uninfected. TOS displayed a positive correlation with the density of parasitaemia and a weak negative correlation with the birth weight and gestational age in infected cord blood. Conclusion Cord blood infection lowers the complement haemolytic titter, oxygen radicals and total antioxidant defense in neonates. This lowering of complement haemolytic titter and oxygen radical compounds in umbilical cord malaria are associated with low birth weight and preterm birth.