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Background: Parasitological confirmation of malaria prior to treatment is recommended by the World Health Organisation (WHO). However, more sensitive and high throughput diagnostic tools are required to support the new pursuit for malaria elimination. The challenge of deploying molecular tools like polymerase chain reaction (PCR) in peripheral settings where they are most needed remains a concern, thus isothermal amplification methods such as loop mediated isothermal amplification (LAMP) are being developed. In this study, we report the evaluation of a novel, inhouse developed LAMP assay targeting the apicoplast genome, in a field setting in sub-Saharan Africa. Methods & Materials: The study was carried out in the screening stage of an ongoing trial (PRINOGAM) comparing different single doses of Primaquine on gametocyte carriage among individuals with asymptomatic malaria. Samples were collected from consenting individuals in the study villages around the Medical Research Council (MRC) field site in Basse, The Gambia, from October to December 2014. From a single finger prick, samples were collected from 341 participants for microscopy, RDT and dried blood spots (DBS). DNA was extracted from the DBS using a simple methanol extraction method for the LAMP assay, and a QIAamp DNA mini kit for the reference PCR assay. Results: A mean of 27±9.5 samples were collected daily. Median age of individuals screened was nine years, ranging from 1-68 years; most study subjects (78%) were less than 15 years old. Malaria prevalence by microscopy was 30% (104/341) and although prevalence byRDT(126/341; 37%) andLAMP(127/341; 37%) did not differ, the agreement was significantly different. Compared to the reference PCR method, LAMP had a sensitivity of 92%, specificity of 97%, positive predictive value (PPV) and negative predictive value (NPV) of 95%. Microscopy had a sensitivity of 78%, specificity of 99%, PPV of 98% and NPV of 88%. Sensitivity, specificity, PPV and NPV for RDT were 76, 88, 79 and 86%, respectively. The turnaround time for the LAMP assay was approximately 3 hrs 30 mins. Conclusion: As it becomes more feasible to deploy molecular tools for diagnosis of malaria at peripheral levels, global eradication of malaria can gradually become a reality. [ABSTRACT FROM AUTHOR]

Abstract Background Malaria cases attributed to Plasmodium falciparum account for approximately 600,000 deaths yearly, mainly in African children. The gold standard method to diagnose malaria requires the visualization of the parasite in blood. The role of non-invasive diagnostic methods to diagnose malaria remains unclear. Methods A protocol was optimized to deplete highly abundant proteins from saliva to improve the dynamic range of the proteins identified and assess their suitability as candidate biomarkers of malaria infection. A starch-based amylase depletion strategy was used in combination with four different lectins to deplete glycoproteins (Concanavalin A and Aleuria aurantia for N-linked glycoproteins; jacalin and peanut agglutinin for O-linked glycoproteins). A proteomic analysis of depleted saliva samples was performed in 17 children with fever and a positive–malaria slide and compared with that of 17 malaria-negative children with fever. Results The proteomic signature of malaria-positive patients revealed a strong up-regulation of erythrocyte-derived and inflammatory proteins. Three P. falciparum proteins, PFL0480w, PF08_0054 and PFI0875w, were identified in malaria patients and not in controls. Aleuria aurantia and jacalin showed the best results for parasite protein identification. Conclusions This study shows that saliva is a suitable clinical specimen for biomarker discovery. Parasite proteins and several potential biomarkers were identified in patients with malaria but not in patients with other causes of fever. The diagnostic performance of these markers should be addressed prospectively.

Abstract Background Health record-based observations from several parts of Africa indicate a major decline in malaria, but up-to-date information on parasite prevalence in West-Africa is sparse. This study aims to provide parasite prevalence data from three sites in the Gambia and Guinea Bissau, respectively, and compares the usefulness of PCR, rapid diagnostic tests (RDT), serology and slide-microscopy for surveillance. Methods Cross-sectional surveys in 12 villages at three rural sites were carried out in the Gambia and Guinea Bissau in January/February 2008, shortly following the annual transmission season. Results A surprisingly low microscopically detectable parasite prevalence was detected in the Gambia (Farafenni: 10.9%, CI95%: 8.7-13.1%; Basse: 9.0%, CI95%: 7.2-10.8%), and Guinea Bissau (Caio: 4%, CI95%: 2.6-5.4%), with low parasite densities (geometric mean: 104 parasites/μl, CI95%: 76-143/μl). In comparison, PCR detected a more than three times higher proportion of parasite carriers, indicating its usefulness to sensitively identify foci where malaria declines, whereas the RDT had very low sensitivity. Estimates of force of infection using age sero-conversion rates were equivalent to an EIR of approximately 1 infectious bite/person/year, significantly less than previous estimates. The sero-prevalence profiles suggest a gradual decline of malaria transmission, confirming their usefulness in providing information on longer term trends of transmission. A greater variability in parasite prevalence among villages within a site than between sites was observed with all methods. The fact that serology equally captured the inter-village variability, indicates that the observed heterogeneity represents a stable pattern. Conclusion PCR and serology may be used as complementary tools to survey malaria in areas of declining malaria prevalence such as the Gambia and Guinea Bissau.

Background: Rapid diagnostic tests (RDTs) provide quick, easy, and convenient early diagnosis of malaria ensuring better case management particularly in resource-constrained settings. Nevertheless, the efficiency of HRP2-based RDT can be compromised by Plasmodium falciparum histidine-rich protein 2/3 gene deletion and genetic diversity. This study explored the genetic diversity of PfHRP2/3 in uncomplicated malaria cases from Ethiopia., Methods: A cross-sectional study was conducted from June 2022 to March 2023 at Metehara, Zenzelema and Kolla Shele health centres, Ethiopia. Finger-prick blood samples were collected for RDT testing and microscopic examination. For molecular analysis, parasite genomic DNA was extracted from venous blood. Plasmodium falciparum was confirmed using VarATS real time PCR. Additionally, PfHRP2/3 was amplified, and DNA amplicons were sequenced using Oxford Nanopore technology., Results: PfHRP2/3 sequences revealed small variations in the frequency and number of amino acid repeat types per isolate across the three health centres. Twelve and eight types of amino acid repeats were identified for PfHRP2 and PfHRP3, respectively, which had been previously characterized. Repeat type 1, 4 and 7 were present in both PfHRP2 and PfHRP3 amino acid sequences. Type 2 and 7 repeats were commonly dispersed in PfHRP2, while repeat types 16 and 17 were found only in PfHRP3. A novel 17 V repeat type variant, which has never been reported in Ethiopia, was identified in six PfHRP3 amino acid sequences. The majority of the isolates, as determined by the Baker's logistic regression model, belonged to group C, of which 86% of them were sensitive to PfHRP2-based RDT. Likewise, PfHRP2-based RDT detected 100% of the isolates in group A (product of type 2 × type 7 repeats ≥ 100) and 85.7% in group B (product of types 2 × type 7 repeats 50-99) at a parasitaemia level > 250 parasite/μl., Conclusion: This study highlights the significant diversity observed in PfHRP2 and PfHRP3 among clinical isolates of Plasmodium falciparum in Ethiopia. This emphasizes the necessity for monitoring of PfHRP2- based RDT efficacy and their repeat type distribution using a large sample size and isolates from various ecological settings., (© 2024. The Author(s).)

Background: Pfcrt gene has been associated with chloroquine resistance and the pfmdr1 gene can alter malaria parasite susceptibility to lumefantrine, mefloquine, and chloroquine. In the absence of chloroquine (CQ) and extensive use of artemether-lumefantrine (AL) from 2004 to 2020 to treat uncomplicated falciparum malaria, pfcrt haplotype, and pfmdr1 single nucleotide polymorphisms (SNPs) were determined in two sites of West Ethiopia with a gradient of malaria transmission., Methods: 230 microscopically confirmed P. falciparum isolates were collected from Assosa (high transmission area) and Gida Ayana (low transmission area) sites, of which 225 of them tested positive by PCR. High-Resolution Melting Assay (HRM) was used to determine the prevalence of pfcrt haplotypes and pfmdr1 SNPs. Furthermore, the pfmdr1 gene copy number (CNV) was determined using real-time PCR. A P-value of less or equal to 0.05 was considered significant., Results: Of the 225 samples, 95.5%, 94.4%, 86.7%, 91.1%, and 94.2% were successfully genotyped with HRM for pfcrt haplotype, pfmdr1-86, pfmdr1-184, pfmdr1-1042 and pfmdr1-1246, respectively. The mutant pfcrt haplotypes were detected among 33.5% (52/155) and 80% (48/60) of isolates collected from the Assosa and Gida Ayana sites, respectively. Plasmodium falciparum with chloroquine-resistant haplotypes was more prevalent in the Gida Ayana area compared with the Assosa area (COR = 8.4, P = 0.00). Pfmdr1-N86Y wild type and 184F mutations were found in 79.8% (166/208) and 73.4% (146/199) samples, respectively. No single mutation was observed at the pfmdr1-1042 locus; however, 89.6% (190/212) of parasites in West Ethiopia carry the wild-type D1246Y variants. Eight pfmdr1 haplotypes at codons N86Y-Y184F-D1246Y were identified with the dominant NFD 61% (122/200). There was no difference in the distribution of pfmdr1 SNPs, haplotypes, and CNV between the two study sites (P > 0.05)., Conclusion: Plasmodium falciparum with the pfcrt wild-type haplotype was prevalent in high malaria transmission site than in low transmission area. The NFD haplotype was the predominant haplotype of the N86Y-Y184F-D1246Y. A continuous investigation is needed to closely monitor the changes in the pfmdr1 SNPs, which are associated with the selection of parasite populations by ACT., (© 2023. The Author(s).)

Background: Genetic diversity of malaria parasites can inform the intensity of transmission and poses a major threat to malaria control and elimination interventions. Characterization of the genetic diversity would provide essential information about the ongoing control efforts. This study aimed to explore allelic polymorphism of merozoite surface protein 1 (msp1) and merozoite surface protein 2 (msp2) to determine the genetic diversity and multiplicity of Plasmodium falciparum infections circulating in high and low transmission sites in western Ethiopia., Methods: Parasite genomic DNA was extracted from a total of 225 dried blood spots collected from confirmed uncomplicated P. falciparum malaria-infected patients in western Ethiopia. Of these, 72.4% (163/225) and 27.6% (62/225) of the samples were collected in high and low transmission areas, respectively. Polymorphic msp1 and msp2 genes were used to explore the genetic diversity and multiplicity of falciparum malaria infections. Genotyping of msp1 was successful in 86.5% (141/163) and 88.7% (55/62) samples collected from high and low transmission areas, respectively. Genotyping of msp2 was carried out among 85.3% (139/163) and 96.8% (60/62) of the samples collected in high and low transmission sites, respectively. Plasmodium falciparum msp1 and msp2 genes were amplified by nested PCR and the PCR products were analysed by QIAxcel ScreenGel Software. A P-value of less or equal to 0.05 was considered significant., Results: High prevalence of falciparum malaria was identified in children less than 15 years as compared with those  ≥ 15 years old (AOR = 2.438, P = 0.005). The three allelic families of msp1 (K1, MAD20, and RO33) and the two allelic families of msp2 (FC27 and 3D7), were observed in samples collected in high and low transmission areas. However, MAD 20 and FC 27 alleles were the predominant allelic families in both settings. Plasmodium falciparum isolates circulating in western Ethiopia had low genetic diversity and mean MOI. No difference in mean MOI between high transmission sites (mean MOI 1.104) compared with low transmission area (mean MOI 1.08) (p > 0.05). The expected heterozygosity of msp1 was slightly higher in isolates collected from high transmission sites (He = 0.17) than in those isolates from low transmission (He = 0.12). However, the heterozygosity of msp2 was not different in both settings (Pfmsp2: 0.04 in high transmission; pfmsp2: 0.03 in low transmission)., Conclusion: Plasmodium falciparum from clinical malaria cases in western Ethiopia has low genetic diversity and multiplicity of infection irrespective of the intensity of transmission at the site of sampling. These may be signaling the effectiveness of malaria control strategies in Ethiopia; although further studies are required to determine how specific intervention strategies and other parameters that drive the pattern., (© 2022. The Author(s).)

To determine the diversity and connectivity of infections in Northwestern and Southwestern Cameroon, 232 Plasmodium falciparum infections, collected in 2018 from the Ndop Health District (NHD) in the western savannah highlands in the Northwest and the Limbe Health District (LHD) in the coastal lowland forests in the Southwest of Cameroon were genotyped for nine neutral microsatellite markers. Overall infection complexity and genetic diversity was significantly (p < 0.05) lower in NHD than LHD, (Mean MOI = 2.45 vs. 2.97; Fws = 0.42 vs. 0.47; Mean He = 0.84 vs. 0.89, respectively). Multi-locus linkage disequilibrium was generally low but significantly higher in the NHD than LHD population (mean I S A = 0.376 vs 0.093). Consequently, highly related pairs of isolates were observed in NHD (mean IBS = 0.086) compared to those from the LHD (mean IBS = 0.059). Infections from the two regions were mostly unrelated (mean IBS = 0.059), though the overall genetic differentiation across the geographical range was low. Indices of differentiation between the populations were however significant (overall pairwise Fst = 0.048, Jost's D = 0.133, p < 0.01). Despite the high human migration across the 270km separating the study sites, these results suggest significant restrictions to gene flow against contiguous geospatial transmission of malaria in west Cameroon. Clonal infections in the highland sites could be driven by lower levels of malaria prevalence and seasonal transmission. How these differences in genetic diversity and complexity affect responses to interventions such as drugs will require further investigations from broader community sampling.

The emergence of artemisinin-resistant parasites in Africa has had a devastating impact, causing most malaria cases and related deaths reported on the continent. In Ethiopia, artemether-lumefantrine (AL) is the first-line drug for the treatment of uncomplicated falciparum malaria. This study is one of the earliest evaluations of artemether-lumefantrine (AL) efficacy in western Ethiopia, 17 years after the introduction of this drug in the study area. This study aimed at assessing PCR- corrected clinical and parasitological responses at 28 days following AL treatment. Sixty uncomplicated falciparum malaria patients were enrolled, treated with standard doses of AL, and monitored for 28 days with clinical and parasitological assessments from September 15 to December 15, 2020. Microscopy was used for patient recruitment and molecular diagnosis of P. falciparum was performed by Var gene acidic terminal sequence ( varATS ) real-time PCR on dried blood spots collected from each patient from day 0 and on follow-up days 1, 2, 3, 7, 14, 21, and 28. MspI and msp2 genotyping was done to confirm occurrence of recrudescence. Data entry and analysis were done by using the WHO-designed Excel spreadsheet and SPSS version 20 for Windows. A P value of less or equal to 0.05 was considered significant. From a total of 60 patients enrolled in this efficacy study, 10 were lost to follow-up; the results were analyzed for 50 patients. All the patients were fever-free on day 3. The asexual parasite positivity rate on day 3 was zero. However; 60% of the patients were PCR positive on day 3. PCR positivity on day 3 was more common among patients <15 years old as compared with those ≥15 years old (AOR = 6.44, P  = 0.027). Only two patients met the case definition of treatment failure. These patients were classified as a late clinical failure as they showed symptoms of malaria and asexual stages of the parasite detected by microscopy on day 14 of their follow-ups. Hence, the Kaplan-Meier analysis of PCR- corrected adequate clinical and parasitological response (ACPR) rate of AL among study participants was 96% (95% CI: 84.9-99). In seven patients, the residual submicroscopic parasitemia persists from day 0 to day 28 of the follow-up. In addition, 16% (8/50) of patients were PCR- and then turned PCR+ after day 7 of the follow-up. AL remains efficacious for the treatment of uncomplicated falciparum malaria in the study area. However, the persistence of PCR-detected residual submicroscopic parasitemia following AL might compromise this treatment and need careful monitoring.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is evolving differently in Africa than in other regions. Africa has lower SARS-CoV-2 transmission rates and milder clinical manifestations. Detailed SARS-CoV-2 epidemiologic data are needed in Africa. We used publicly available data to calculate SARS-CoV-2 infections per 1,000 persons in The Gambia. We evaluated transmission rates among 1,366 employees of the Medical Research Council Unit The Gambia (MRCG), where systematic surveillance of symptomatic cases and contact tracing were implemented. By September 30, 2020, The Gambia had identified 3,579 SARS-CoV-2 cases, including 115 deaths; 67% of cases were identified in August. Among infections, MRCG staff accounted for 191 cases; all were asymptomatic or mild. The cumulative incidence rate among nonclinical MRCG staff was 124 infections/1,000 persons, which is >80-fold higher than estimates of diagnosed cases among the population. Systematic surveillance and seroepidemiologic surveys are needed to clarify the extent of SARS-CoV-2 transmission in Africa.

Objective: To estimate the prevalence of antibodies against Coxiella burnetii (Q fever) among children in eight villages in The Gambia, West Africa., Methods: Sera of 796 children aged 1-15 years were tested for presence of antibodies against phase II of C. burnetii by ELISA., Results: IgG and/or IgM phase II antibodies against C. burnetii were detectable in 8.3% (66/796) of all serum samples analysed with significant differences in seroprevalence between villages. Highest prevalence was found in the age group 1-4 years., Conclusions: Exposure to C. burnetii is considerable in the early years of life in The Gambia, and further studies are warranted to estimate the role of Q fever in acute febrile illness in The Gambia and elsewhere in Africa., (© 2013 Blackwell Publishing Ltd.)

Background: In areas of declining malaria transmission such as in The Gambia, the identification of malaria infected individuals becomes increasingly harder. School surveys may be used to identify foci of malaria transmission in the community., Methods: The survey was carried out in May-June 2011, before the beginning of the malaria transmission season. Thirty two schools in the Upper River Region of The Gambia were selected with probability proportional to size; in each school approximately 100 children were randomly chosen for inclusion in the study. Each child had a finger prick blood sample collected for the determination of antimalarial antibodies by ELISA, malaria infection by microscopy and PCR, and for haemoglobin measurement. In addition, a simple questionnaire on socio-demographic variables and the use of insecticide-treated bed nets was completed. The cut-off for positivity for antimalarial antibodies was obtained using finite mixture models. The clustered nature of the data was taken into account in the analyses., Results: A total of 3,277 children were included in the survey. The mean age was 10 years (SD = 2.7) [range 4-21], with males and females evenly distributed. The prevalence of malaria infection as determined by PCR was 13.6% (426/3124) [95% CI = 12.2-16.3] with marked variation between schools (range 3-25%, p<0.001), while the seroprevalence was 7.8% (234/2994) [95%CI = 6.4-9.8] for MSP119, 11.6% (364/2997) [95%CI = 9.4-14.5] for MSP2, and 20.0% (593/2973) [95% CI = 16.5-23.2) for AMA1. The prevalence of all the three antimalarial antibodies positive was 2.7% (79/2920)., Conclusions: This survey shows that malaria prevalence and seroprevalence before the transmission season were highly heterogeneous.

Polymerase chain reaction (PCR) has been shown to be more sensitive in detecting low-level parasitemia than conventional blood film microscopy. We estimated the prevalence of congenital malaria using nested PCR amplification of the small subunit 18S RNA gene to detect low-level parasitemia and identify Plasmodium species in 204 mother-neonate pairs. Cord-blood parasitemia was detected in four babies by PCR, giving a prevalence of 2.0%. The newborns of primidgravidae were more susceptible to congenital malaria than those of multigravidae (P < 0.0001). There was a strong correlation between placental malaria and congenital malaria (odds ratio = 10.1, 95% confidence interval = 1.3-76.1, P = 0.0487). We conclude that the prevalence of congenital malaria in Calabar detected by PCR is lower than has been reported in this environment through microscopy.