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Lamsfus Calle C, Schaumburg F, Rieck T, Nkoma Mouima AM, Martinez de Salazar P, Breil S, Behringer J, Kremsner PG, Mordmüller B, Fendel R. Slow clearance of histidine-rich protein-2 in Gabonese with uncomplicated malaria. Microbiol Spectr 2024:e0099424. [PMID: 39194289 DOI: 10.1128/spectrum.00994-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2024] [Accepted: 07/31/2024] [Indexed: 08/29/2024] Open
Abstract
Malaria rapid diagnostic tests (RDTs), which detect Plasmodium falciparum (Pf)-specific histidine-rich protein-2 (HRP2), have increasing importance for the diagnosis and control of malaria, especially also in regions where routine diagnosis by microscopy is not available. HRP2-based RDTs have a similar sensitivity to expert microscopy, but their reported low specificity can lead to high false positivity rates, particularly in high-endemic areas. Despite the widespread use of RDTs, models investigating the dynamics of HRP2 clearance following Pf treatment focus rather on short-term clearance of the protein. The goal of this observational cohort study was to determine the long-term kinetic of HRP2-levels in peripheral blood after treatment of uncomplicated malaria cases with Pf mono-infection using a 3-day course of artesunate/amodiaquine. HRP2 levels were quantified at enrollment and on days 1, 2, 3, 5, 7, 12, 17, 22, and 28 post-treatment initiation. The findings reveal an unexpectedly prolonged clearance of HRP2 after parasite clearance from capillary blood. Terminal HRP2 half-life was estimated to be 9 days after parasite clearance using a pharmacokinetic two-compartmental elimination model. These results provide evidence that HRP2 clearance has generally been underestimated, as the antigen remains detectable in capillary blood for up to 28 days following successful treatment, influencing RDT-based assessment following a malaria treatment for weeks. A better understanding of the HRP2 clearance dynamics is critical for guiding the diagnosis of malaria when relying on RDTs. IMPORTANCE Detecting Plasmodium falciparum, the parasite responsible for the severest form of malaria, typically involves microscopy, polymerase chain reaction (PCR), or rapid diagnostic tests (RDTs) targeting the histidine-rich protein 2 or 3 (HRP2/3). While microscopy and PCR quickly turn negative after the infection is cleared, HRP2 remains detectable for a prolonged period. The exact duration of HRP2 persistence had not been well defined. Our study in Gabon tracked HRP2 levels over 4 weeks, resulting in a new model for antigen clearance. We discovered that a two-compartment model accurately predicts HRP2 levels, revealing an initial rapid reduction followed by a much slower elimination phase that can take several weeks. These findings are crucial for interpreting RDT results, as lingering HRP2 can lead to false positives, impacting malaria diagnosis and treatment decisions.
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Affiliation(s)
- Carlos Lamsfus Calle
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- German Center for Infection Research (DZIF), Partner Site Tübingen, Tübingen, Germany
| | - Frieder Schaumburg
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
- Institute of Medical Microbiology, University Hospital Münster, Münster, Germany
| | - Thorsten Rieck
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
| | - Anne Marie Nkoma Mouima
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
| | - Pablo Martinez de Salazar
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
- Swiss Tropical and public Health Institute, Allschwil, Switzerland
| | - Saskia Breil
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
| | | | - Peter G Kremsner
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- German Center for Infection Research (DZIF), Partner Site Tübingen, Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
| | - Benjamin Mordmüller
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Rolf Fendel
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- German Center for Infection Research (DZIF), Partner Site Tübingen, Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
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Adeniji YR, Jalo I, Okonkwo I, Poksireni MR, Manga M, Wariri O, Alhassan HA, Warnow EI. Diagnostic value of rapid test for malaria among febrile neonates in a tertiary hospital in North-East Nigeria: a prospective cross-sectional study. Arch Dis Child 2023; 109:11-15. [PMID: 37879855 PMCID: PMC10803997 DOI: 10.1136/archdischild-2023-325906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Accepted: 08/30/2023] [Indexed: 10/27/2023]
Abstract
OBJECTIVE The WHO recommends testing using microscopy or rapid diagnostic test (RDT) before treatment for malaria. However, the use of RDT to diagnose neonatal malaria has not been widely validated with most studies limited to the first week of life. Thus, we conducted this study to determine the utility of RDT in the diagnosis of congenital and acquired malaria in febrile neonates in Nigeria. DESIGN This prospective cross-sectional descriptive study consecutively recruited 131 febrile neonates at the Special Care Baby Unit (SCBU) of the Federal Teaching Hospital Gombe, Nigeria. All study participants concurrently had RDT (HRP2, LDH) and malaria microscopy. The performance of both methods was then compared. RESULT Seventy-eight of 131 neonates tested for malaria by blood smear microscopy demonstrated malaria parasites; a prevalence of 59.5%. Parasite count ranged from 16 to 520 /μL and the median parasite count was 81.0 /μL with IQR (40.0-134.5). The majority of patients (93.5%) had low-density parasitaemia (≤2+). All species identified were Plasmodium falciparum. None of the 131 neonates tested positive on RDT. The sensitivity and positive predictive value of RDT for neonatal malaria was zero. Congenital malaria was the most common form of neonatal malaria, accounting for 75.6%, while acquired and transfusion-related malaria were estimated at 12.8% and 11.6%, respectively. CONCLUSION The RDT used in this study was not sensitive in the diagnosis of congenital or acquired neonatal malaria; therefore, microscopy remains the preferred method of diagnosis of neonatal malaria.
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Affiliation(s)
| | - Iliya Jalo
- Department of Paediatrics, Federal Teaching Hospital Gombe, Gombe, Nigeria
| | - Ikechukwu Okonkwo
- Department of Child Health, University of Benin Teaching Hospital, Benin City, Nigeria
| | | | - Mohammed Manga
- Medical Microbiology, Federal Teaching Hospital Gombe, Gombe, Nigeria
| | - Oghenebrume Wariri
- Vaccines and Immunity Theme, MRC Unit The Gambia at London School of Hygiene and Tropical Medicine, Banjul, Gambia
| | | | - Elon Isaac Warnow
- Department of Paediatrics, Federal Teaching Hospital Gombe, Gombe, Nigeria
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Martiáñez-Vendrell X, Skjefte M, Sikka R, Gupta H. Factors Affecting the Performance of HRP2-Based Malaria Rapid Diagnostic Tests. Trop Med Infect Dis 2022; 7:265. [PMID: 36288006 PMCID: PMC9611031 DOI: 10.3390/tropicalmed7100265] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 09/14/2022] [Accepted: 09/21/2022] [Indexed: 11/16/2022] Open
Abstract
The recent COVID-19 pandemic has profoundly impacted global malaria elimination programs, resulting in a sharp increase in malaria morbidity and mortality. To reduce this impact, unmet needs in malaria diagnostics must be addressed while resuming malaria elimination activities. Rapid diagnostic tests (RDTs), the unsung hero in malaria diagnosis, work to eliminate the prevalence of Plasmodium falciparum malaria through their efficient, cost-effective, and user-friendly qualities in detecting the antigen HRP2 (histidine-rich protein 2), among other proteins. However, the testing mechanism and management of malaria with RDTs presents a variety of limitations. This paper discusses the numerous factors (including parasitic, host, and environmental) that limit the performance of RDTs. Additionally, the paper explores outside factors that can hinder RDT performance. By understanding these factors that affect the performance of HRP2-based RDTs in the field, researchers can work toward creating and implementing more effective and accurate HRP2-based diagnostic tools. Further research is required to understand the extent of these factors, as the rapidly changing interplay between parasite and host directly hinders the effectiveness of the tool.
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Affiliation(s)
- Xavier Martiáñez-Vendrell
- Molecular Virology Laboratory, Department of Medical Microbiology, LUMC Center for Infectious Diseases (LU-CID), Leiden University Medical Center, 2333 ZA Leiden, The Netherlands or
| | - Malia Skjefte
- Department of Global Health and Population, Harvard TH Chan School of Public Health, Boston, MA 02115, USA
| | - Ruhi Sikka
- Department of Biotechnology, Institute of Applied Sciences & Humanities, GLA University, Mathura 281406, UP, India
| | - Himanshu Gupta
- Department of Biotechnology, Institute of Applied Sciences & Humanities, GLA University, Mathura 281406, UP, India
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Pujo JM, Houcke S, Lemmonier S, Portecop P, Frémery A, Blanchet D, Djossou F, Kallel H, Demar M. Accuracy of SD Malaria Ag P.f/Pan® as a rapid diagnostic test in French Amazonia. Malar J 2021; 20:369. [PMID: 34535137 PMCID: PMC8447521 DOI: 10.1186/s12936-021-03902-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Accepted: 09/02/2021] [Indexed: 12/04/2022] Open
Abstract
Background French Guiana (FG) is a French overseas territory where malaria is endemic. The current incidence rate is 0.74‰ inhabitants, and Plasmodium vivax is widely predominating even though Plasmodium falciparum is still present due to imported cases mainly from Africa. In FG, rapid diagnostic test (SD Malaria Ag P.f/Pan®) is based on the detection of pan-pLDH, PfHRP2, and PfHRP3 antigens, while in South America, the share of deletion of PfHRP2 gene is significantly increasing. Accordingly, the study questions the reliability of RDTs in the Amazonian context. Methods The study is retrospective. It is conducted over 4 years and analysed 12,880 rapid diagnostic tests (RDTs) compared to concomitant Blood Film Tests (BFTs) sampled for malaria diagnosis. Results The global assessment of the accuracy of SD Malaria Ag P.f/Pan® in the diagnostic of malaria shows both Positive and Negative Predictive Values (PPV and NPV) higher than 95%, except for PPV in the diagnosis of malaria to P. falciparum (88%). Overall, the concordance rate between RDT and BFT (positive/positive; negative/negative) was 99.5%. The PPV of the RDT in the follow-up of patients diagnosed with P. falciparum was the lowest during the first 28 days. The PPV of the RDT in the follow-up of patients diagnosed with P. vivax was the lowest during the first 21 days. The global sensitivity of SD Malaria Ag P.f/Pan® test was, on average, 96% (88.2–100) for P. falciparum and 93% (90.6–94.2) for P. vivax. The global specificity was 99.8% (99.5–100) for all included species. Conclusion SD Malaria Ag P.f/Pan® is a reliable rapid test used for the first-line diagnosis in remote healthcare centres. The test results should be interpreted in the light of patient’s recent medical history and the date of arrival to FG.
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Affiliation(s)
- Jean Marc Pujo
- Emergency Department, Cayenne General Hospital, Cayenne, French Guiana.
| | - Stéphanie Houcke
- Intensive Care Unit, Cayenne General Hospital, Cayenne, French Guiana
| | - Sarah Lemmonier
- Emergency Department, Cayenne General Hospital, Cayenne, French Guiana
| | - Patrick Portecop
- Emergency Department, Guadeloupe University Hospital, Les Abymes, Guadeloupe
| | - Alexis Frémery
- Emergency Department, Cayenne General Hospital, Cayenne, French Guiana
| | - Denis Blanchet
- Academic Laboratory of Parasitology-Mycology, Cayenne General Hospital, Cayenne, French Guiana.,Tropical Biome and Immunophysiopathology (TBIP), Université de Guyane, Cayenne, 97300, French Guiana.,Université de Lille, CNRS, Inserm, Institut Pasteur de Lille, U1019-UMR9017-CIIL Centre d'Infection Et d'Immunité de Lille, 59000, Lille, France
| | - Felix Djossou
- Infectious and Tropical Diseases Unit, Cayenne General Hospital, Cayenne, French Guiana
| | - Hatem Kallel
- Intensive Care Unit, Cayenne General Hospital, Cayenne, French Guiana.,Tropical Biome and Immunophysiopathology (TBIP), Université de Guyane, Cayenne, 97300, French Guiana.,Université de Lille, CNRS, Inserm, Institut Pasteur de Lille, U1019-UMR9017-CIIL Centre d'Infection Et d'Immunité de Lille, 59000, Lille, France
| | - Magalie Demar
- Academic Laboratory of Parasitology-Mycology, Cayenne General Hospital, Cayenne, French Guiana.,Tropical Biome and Immunophysiopathology (TBIP), Université de Guyane, Cayenne, 97300, French Guiana.,Université de Lille, CNRS, Inserm, Institut Pasteur de Lille, U1019-UMR9017-CIIL Centre d'Infection Et d'Immunité de Lille, 59000, Lille, France
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Songsaigath S, Makiuchi T, Putaporntip C, Pattanawong U, Kuamsab N, Tachibana H, Jongwutiwes S. Immunoglobulin G responses to variant forms of Plasmodium vivax merozoite surface protein 9 upon natural infection in Thailand. Sci Rep 2021; 11:3201. [PMID: 33547377 PMCID: PMC7864938 DOI: 10.1038/s41598-021-82928-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 01/25/2021] [Indexed: 11/30/2022] Open
Abstract
Merozoite surface protein 9 (MSP9) constitutes a ligand complex involved in erythrocyte invasion by malarial merozoites and is a promising vaccine target. Plasmodium vivax MSP9 (PvMSP9) is immunogenic upon natural malaria exposure. To address whether sequence diversity in PvMSP9 among field isolates could affect natural antibody responses, the recombinant proteins representing two variants each for the N- and the C-terminal domains of PvMSP-9 were used as antigens to assess antibody reactivity among 246 P. vivax-infected patients’ sera from Tak and Ubon Ratchathani Provinces in Thailand. Results revealed that the seropositivity rates of IgG antibodies to the N-terminal antigens were higher than those to the C-terminal antigens (87.80% vs. 67.48%). Most seropositive sera were reactive to both variants, suggesting the presence of common epitopes. Variant-specific antibodies to the N- and the C-terminal antigens were detected in 15.85% and 16.70% of serum samples, respectively. These seropositivity rates were not significant difference between provinces. The seropositivity rates, levels and avidity of anti-PvMSP9 antibodies exhibited positive trends towards increasing malaria episodes. The IgG isotype responses to the N- and the C-terminal antigens were mainly IgG1 and IgG3. The profile of IgG responses may have implications for development of PvMSP9-based vaccine.
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Affiliation(s)
- Sunisa Songsaigath
- Department of Infectious Diseases, Tokai University School of Medicine, Isehara, Kanagawa, Japan.,Molecular Biology of Malaria and Opportunistic Parasites Research Unit, Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.,Inter-Department Program of Biomedical Sciences, Faculty of Graduate School, Chulalongkorn University, Bangkok, Thailand
| | - Takashi Makiuchi
- Department of Infectious Diseases, Tokai University School of Medicine, Isehara, Kanagawa, Japan
| | - Chaturong Putaporntip
- Molecular Biology of Malaria and Opportunistic Parasites Research Unit, Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Urassaya Pattanawong
- Molecular Biology of Malaria and Opportunistic Parasites Research Unit, Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Napaporn Kuamsab
- Molecular Biology of Malaria and Opportunistic Parasites Research Unit, Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Hiroshi Tachibana
- Department of Infectious Diseases, Tokai University School of Medicine, Isehara, Kanagawa, Japan.
| | - Somchai Jongwutiwes
- Molecular Biology of Malaria and Opportunistic Parasites Research Unit, Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
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Martiáñez-Vendrell X, Jiménez A, Vásquez A, Campillo A, Incardona S, González R, Gamboa D, Torres K, Oyibo W, Faye B, Macete E, Menéndez C, Ding XC, Mayor A. Quantification of malaria antigens PfHRP2 and pLDH by quantitative suspension array technology in whole blood, dried blood spot and plasma. Malar J 2020; 19:12. [PMID: 31918718 PMCID: PMC6953214 DOI: 10.1186/s12936-019-3083-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 12/21/2019] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Malaria diagnostics by rapid diagnostic test (RDT) relies primarily on the qualitative detection of Plasmodium falciparum histidine-rich protein 2 (PfHRP2) and Plasmodium spp lactate dehydrogenase (pLDH). As novel RDTs with increased sensitivity are being developed and implemented as point of care diagnostics, highly sensitive laboratory-based assays are needed for evaluating RDT performance. Here, a quantitative suspension array technology (qSAT) was developed, validated and applied for the simultaneous detection of PfHRP2 and pLDH in a variety of biological samples (whole blood, plasma and dried blood spots) from individuals living in different endemic countries. RESULTS The qSAT was specific for the target antigens, with analytical ranges of 6.8 to 762.8 pg/ml for PfHRP2 and 78.1 to 17076.6 pg/ml for P. falciparum LDH (Pf-LDH). The assay detected Plasmodium vivax LDH (Pv-LDH) at a lower sensitivity than Pf-LDH (analytical range of 1093.20 to 187288.5 pg/ml). Both PfHRP2 and pLDH levels determined using the qSAT showed to positively correlate with parasite densities determined by quantitative PCR (Spearman r = 0.59 and 0.75, respectively) as well as microscopy (Spearman r = 0.40 and 0.75, respectively), suggesting the assay to be a good predictor of parasite density. CONCLUSION This immunoassay can be used as a reference test for the detection and quantification of PfHRP2 and pLDH, and could serve for external validation of RDT performance, to determine antigen persistence after parasite clearance, as well as a complementary tool to assess malaria burden in endemic settings.
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Affiliation(s)
- Xavier Martiáñez-Vendrell
- ISGlobal, Hospital Clínic of Barcelona, Universitat de Barcelona, Carrer Rosselló 153 (CEK building), 08036, Barcelona, Spain
| | - Alfons Jiménez
- ISGlobal, Hospital Clínic of Barcelona, Universitat de Barcelona, Carrer Rosselló 153 (CEK building), 08036, Barcelona, Spain.,Spanish Consortium for Research in Epidemiology and Public Health (CIBERESP), Madrid, Spain
| | - Ana Vásquez
- Grupo Malaria, Facultad de Medicina, Universidad de Antioquia, Medellín, Colombia
| | | | | | - Raquel González
- ISGlobal, Hospital Clínic of Barcelona, Universitat de Barcelona, Carrer Rosselló 153 (CEK building), 08036, Barcelona, Spain.,Spanish Consortium for Research in Epidemiology and Public Health (CIBERESP), Madrid, Spain.,Centro de Investigação em Saúde da Manhiça (CISM), Maputo, Mozambique
| | - Dionicia Gamboa
- Departamento de Ciencias Celulares y Moleculares, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Katherine Torres
- Laboratorio de Malaria, Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Wellington Oyibo
- ANDI Centre of Excellence for Malaria Diagnosis, College of Medicine, University of Lagos, Idi-Aaraba, Lagos, Nigeria
| | - Babacar Faye
- Service de Parasitologie-Mycologie, Faculté de Médecine, Pharmacie et Odontologie, Université Cheikh Anta Diop de Dakar, Dakar, Sénégal
| | - Eusebio Macete
- Centro de Investigação em Saúde da Manhiça (CISM), Maputo, Mozambique
| | - Clara Menéndez
- ISGlobal, Hospital Clínic of Barcelona, Universitat de Barcelona, Carrer Rosselló 153 (CEK building), 08036, Barcelona, Spain.,Spanish Consortium for Research in Epidemiology and Public Health (CIBERESP), Madrid, Spain.,Centro de Investigação em Saúde da Manhiça (CISM), Maputo, Mozambique
| | | | - Alfredo Mayor
- ISGlobal, Hospital Clínic of Barcelona, Universitat de Barcelona, Carrer Rosselló 153 (CEK building), 08036, Barcelona, Spain. .,Spanish Consortium for Research in Epidemiology and Public Health (CIBERESP), Madrid, Spain. .,Centro de Investigação em Saúde da Manhiça (CISM), Maputo, Mozambique.
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Plucinski MM, Herman C, Jones S, Dimbu R, Fortes F, Ljolje D, Lucchi N, Murphy SC, Smith NT, Cruz KR, Seilie AM, Halsey ES, Udhayakumar V, Aidoo M, Rogier E. Screening for Pfhrp2/3-Deleted Plasmodium falciparum, Non-falciparum, and Low-Density Malaria Infections by a Multiplex Antigen Assay. J Infect Dis 2019; 219:437-447. [PMID: 30202972 PMCID: PMC6325347 DOI: 10.1093/infdis/jiy525] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 08/30/2018] [Indexed: 11/13/2022] Open
Abstract
Background Detection of Plasmodium antigens provides evidence of malaria infection status and is the basis for most malaria diagnosis. Methods We developed a sensitive bead-based multiplex assay for laboratory use, which simultaneously detects pan-Plasmodium aldolase (pAldo), pan-Plasmodium lactate dehydrogenase (pLDH), and P. falciparum histidine-rich protein 2 (PfHRP2) antigens. The assay was validated against purified recombinant antigens, monospecies malaria infections, and noninfected blood samples. To test against samples collected in an endemic setting, Angolan outpatient samples (n = 1267) were assayed. Results Of 466 Angolan samples positive for at least 1 antigen, the most common antigen profiles were PfHRP2+/pAldo+/pLDH+ (167, 36%), PfHRP2+/pAldo-/pLDH- (163, 35%), and PfHRP2+/pAldo+/pLDH- (129, 28%). Antigen profile was predictive of polymerase chain reaction (PCR) positivity and parasite density. Eight Angolan samples (1.7%) had no or very low PfHRP2 but were positive for 1 or both of the other antigens. PCR analysis confirmed 3 (0.6%) were P. ovale infections and 2 (0.4%) represented P. falciparum parasites lacking Pfhrp2 and/or Pfhrp3. Conclusions These are the first reports of Pfhrp2/3 deletion mutants in Angola. High-throughput multiplex antigen detection can inexpensively screen for low-density P. falciparum, non-falciparum, and Pfhrp2/3-deleted parasites to provide population-level antigen estimates and identify specimens requiring further molecular characterization.
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Affiliation(s)
- Mateusz M Plucinski
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia
- US President’s Malaria Initiative, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Camelia Herman
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia
- CDC Foundation, Atlanta, Georgia
| | - Sophie Jones
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia
- Atlanta Research and Education Foundation, Georgia
| | - Rafael Dimbu
- National Malaria Control Program, Ministry of Health, Luanda, Angola
| | - Filomeno Fortes
- National Malaria Control Program, Ministry of Health, Luanda, Angola
| | - Dragan Ljolje
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia
- Atlanta Research and Education Foundation, Georgia
| | - Naomi Lucchi
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Sean C Murphy
- Department of Laboratory Medicine, University of Washington, Seattle
- Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle
| | - Nahum T Smith
- Department of Laboratory Medicine, University of Washington, Seattle
| | - Kurtis R Cruz
- Department of Laboratory Medicine, University of Washington, Seattle
| | - Annette M Seilie
- Department of Laboratory Medicine, University of Washington, Seattle
| | - Eric S Halsey
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia
- US President’s Malaria Initiative, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Venkatachalam Udhayakumar
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Michael Aidoo
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Eric Rogier
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia
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Mallepaddi PC, Maity SN, Poonati R, Pyadala N, Polavarapu R, Mangamuri UK, Poda S. Selecting better diagnostic kits for diagnosis of malarial parasites at point of care. 3 Biotech 2019; 9:36. [PMID: 30622874 DOI: 10.1007/s13205-018-1566-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Accepted: 12/31/2018] [Indexed: 10/27/2022] Open
Abstract
Malaria is a fatal life-threatening parasitic infection and a leading cause of morbidity and mortality. The present study was aimed to evaluate simple, inexpensive, accurate, reliable, easily available better diagnostic for rapid detection of malaria at point of care (POC). The study includes 1403 samples collected from the patients, of which 1227 were clinically suspected cases and 176 from consecutive feverish patients. Among the suspected cases only 338 samples were confirmed positive and 889 samples were negative for Plasmodium species by PCR. All the 889 samples showed negative result for plasmodium species by microscopy, Malarial Ag rapid kits but only 867 samples were confirmed negative with malarial Ab rapid kits. Of the 338 PCR positive samples, 337 samples were confirmed positive by microscopy and Malarial Ag rapid kits, but only 284 samples were confirmed positive using malarial Ab rapid kits. Overall the microscopy and the malaria antigen-based lateral flow assay exhibited similar sensitivity, specificity, PPV, NPV and efficiency, respectively, whereas the PCR assay had 100% sensitivity, specificity, PPV, NPV and efficiency. But the evolutionary data for malaria antibody lateral flow assay has 92.81% sensitivity, 94.13% specificity, 84.02% PPV, 97.52% NPV and 93.80% efficiency. The developed Malaria pf/pv antigen and antibody field-deployable kits are simple, rapid, accurate, reliable, inexpensive, user friendly, POC. In addition the kits are highly sensitive and species-specific. The pf/pv antigen kit is found to be more accurate with 99.7% sensitivity and 100% specificity than to Malaria pf/pv antibody rapid kits. Of the two rapid kits developed, Malaria pf/pv antigen kit is found be more accurate with 99.7% sensitivity and 100% specificity than to Malaria pf/pv antibody rapid kits.
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Nkenfou CN, Hell VN, Georges NT, Ngoufack MN, Nkenfou CN, Kamgaing N, Ndjolo A. USAGE OF A RAPID DIAGNOSTIC TEST FOR MALARIA IN CHILDREN. Afr J Infect Dis 2018; 13:24-31. [PMID: 30596193 PMCID: PMC6305079 DOI: 10.21010/ajid.v13i1.3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 06/14/2017] [Accepted: 07/12/2017] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND Malaria is still the primary cause of pediatric deaths. The efficient management of pediatric malaria requires its rapid and accurate diagnosis. To fulfill this requirement, rapid diagnostic tests have been developed, but their evaluation before commercialization is never exhaustive. The aim of this study was to evaluate the performance of a rapid diagnostic test (SD Bioline Malaria Antigen P.f/Pan) to diagnose malaria in children. MATERIALS AND METHODS Testing was conducted on children aged between 6 months and 15 years who were examined at the "Centre Mère Enfant (CME) of the "Chantal Biya" Foundation (FCB). as a result of fever. Enrollment took place from April to October 2014. All children presenting with fever were sampled (3ml of blood). These blood samples were tested for malaria using microscopy on a thick blood smear and by a rapid diagnostic test (RDT) SD Bioline Malariae Antigen P.f/Pan. RESULTS A total of 249 children were enrolled in this study. Malaria presence as determined by microscopy and by RDT was 30.9% and 58.2% respectively. The sensitivity, specificity, positive and negative predictive values compared to microscopy were: 75; 48.8; 39, and 81.6%. With these performances, the malaria SD Bioline rapid test presents lower values compared to WHO recommendations for rapid tests (sensitivity > 95%) in children. CONCLUSION SD Bioline Malaria Antigen P.f/Pan test should only be used in peripheral health structures that lack resources, and should be aided by clinical diagnosis.
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Affiliation(s)
- Céline Nguefeu Nkenfou
- Laboratory of Systems Biology, “Chantal Biya” International Reference Centre for Research on HIV/AIDS Prevention and Management (CBIRC), Yaounde, Cameroon
- Department of Biological Sciences, Higher Teacher Training College, University of Yaounde I, Yaounde, Cameroon
| | - Vestale Ngo Hell
- Catholic University, School of Health Sciences, Yaounde, Cameroon
| | | | - Marie Nicole Ngoufack
- Laboratory of Systems Biology, “Chantal Biya” International Reference Centre for Research on HIV/AIDS Prevention and Management (CBIRC), Yaounde, Cameroon
- Faculty of Sciences, University of Yaounde I, Yaounde, Cameroon
| | | | - Nelly Kamgaing
- Laboratory of Systems Biology, “Chantal Biya” International Reference Centre for Research on HIV/AIDS Prevention and Management (CBIRC), Yaounde, Cameroon
- Faculty of Medicine and Biomedical Sciences, University of Yaounde, Yaounde, Cameroon
| | - Alexis Ndjolo
- Laboratory of Systems Biology, “Chantal Biya” International Reference Centre for Research on HIV/AIDS Prevention and Management (CBIRC), Yaounde, Cameroon
- Faculty of Medicine and Biomedical Sciences, University of Yaounde, Yaounde, Cameroon
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10
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Markwalter CF, Mudenda L, Leelawong M, Kimmel DW, Nourani A, Mbambara S, Thuma PE, Wright DW. Evidence for histidine-rich protein 2 immune complex formation in symptomatic patients in Southern Zambia. Malar J 2018; 17:256. [PMID: 29986725 PMCID: PMC6038308 DOI: 10.1186/s12936-018-2400-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 06/26/2018] [Indexed: 11/20/2022] Open
Abstract
Background Rapid diagnostic tests based on histidine-rich protein 2 (HRP2) detection are the primary tools used to detect Plasmodium falciparum malaria infections. Recent conflicting reports call into question whether α-HRP2 antibodies are present in human host circulation and if resulting immune complexes could interfere with HRP2 detection on malaria RDTs. This study sought to determine the prevalence of immune-complexed HRP2 in a low-transmission region of Southern Zambia. Methods An ELISA was used to quantify HRP2 in patient sample DBS extracts before and after heat-based immune complex dissociation. A pull-down assay reliant on proteins A, G, and L was developed and applied for IgG and IgM capture and subsequent immunoprecipitation of any HRP2 present in immune complexed form. A total of 104 patient samples were evaluated using both methods. Results Immune-complexed HRP2 was detectable in 17% (18/104) of all samples evaluated and 70% (16/23) of HRP2-positive samples. A majority of the patients with samples containing immune-complexed HRP2 had P. falciparum infections (11/18) and were also positive for free HRP2 (16/18). For 72% (13/18) of patients with immune-complexed HRP2, less than 10% of the total HRP2 present was in immune-complexed form. For the remaining samples, a large proportion (≥ 20%) of total HRP2 was complexed with α-HRP2 antibodies. Conclusions Endogenous α-HRP2 antibodies form immune complexes with HRP2 in the symptomatic patient population of a low-transmission area in rural Southern Zambia. For the majority of patients, the percentage of HRP2 in immune complexes is low and does not affect HRP2-based malaria diagnosis. However, for some patients, a significant portion of the total HRP2 was in immune-complexed form. Future studies investigating the prevalence and proportion of immune-complexed HRP2 in asymptomatic individuals with low HRP2 levels will be required to assess whether α-HRP2 antibodies affect HRP2 detection for this portion of the transmission reservoir. Electronic supplementary material The online version of this article (10.1186/s12936-018-2400-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Lwiindi Mudenda
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA.,Rusangu University, Monze, Zambia
| | - Mindy Leelawong
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA
| | - Danielle W Kimmel
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA
| | - Armin Nourani
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA
| | | | | | - David W Wright
- Department of Chemistry, Vanderbilt University, Nashville, TN, 37235, USA.
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11
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Shittu O, Opeyemi OA, Ajibaye O, Omotesho BO, Fakayode O. Evaluation of the Clinical Proficiency of RDTs, Microscopy and Nested PCR in the Diagnosis of Symptomatic Malaria in Ilorin, North-Central, Nigeria. Open Access Maced J Med Sci 2018; 6:1032-1040. [PMID: 29983797 PMCID: PMC6026432 DOI: 10.3889/oamjms.2018.218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 04/20/2018] [Accepted: 04/30/2018] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND: Accurate laboratory diagnosis of suspected malaria is the hallmark to the control of the disease. AIM: The clinical proficiency of commercial Rapid Diagnostic test kits (RDTs) using nested PCR as quality control was evaluated among patients attending two public healthcare providing institutions in Ilorin, Kwara state, North-Central, Nigeria. METHOD: A cross-sectional evaluation of finger prick blood samples of volunteer patients were accessed for malaria parasites with pLDH, HRP2, Pf, Pf/PAN and nested PCR molecular assays. The data derived were analysed using standard formulae for diagnostic accuracy, and the obtained predictive values were subjected to a comparison with one-way analysis of variance (ANOVA). RESULT: Three hundred and sixty-eight (368) patients comprising 203 (55%) females and 165 (45%) males participated in this study. Routine microscopy revealed that 54 (32.7%) males and 80 (39.4%) was infected with Plasmodium falciparum. SD Bioline (pLDH) 47.4%; Carestart Malaria (HRP2) 49.8% recorded low sensitivities. Micropoint (pfPAN) 82.8% and Micropoint (Mal. Pf) 64.4% recorded a high sensitivity. SD Bioline (pLDH) 67.4%; Carestart Malaria (HRP2) 85.9%; Micropoint (PfPAN) 62.2% and Micropoint (Mal. Pf) 86.7% had high specificities. The positive predictive value (PPV) ranged from 67.7% to 85.94%, while the negative predictive values (NPV) of 64.4% for SD Bioline (pLDH); 86.7% for Carestart Malaria (HRP2); 89.3% for Micropoint (pfPAN) and 58.5% for Micropoint (Mal. Pf). Agarose gel analysis of P. falciparumssrRNA gene (206 bp) for 28 specimens containing 10% concordant and discordant samples showed that all 12 negative specimens for RDTs and routine microscopy were truly negative for nPCR. However, the remaining 16 specimens were positive for nPCR and showed discrepancies with routine microscopy and RDTs. Cohen’s interrater diagnostic measure analysis revealed that the weighted kappa for the RDTs was moderate 0.417 (p=0.027), 95%CI (0.756, 0.078) and good for nPCR 0.720 (p < 0.001), 95%CI (0.963, 0.477). The area under the curve (AUC) specify that nPCR has been more effective than the RDTs (nPCRAUC = 0.875; p < 0.001 and RDTsAUC = 0.708; p = 0.063). CONCLUSION: A thorough large-scale quality control is advocated on all commercial RDTs being used in most sub-Saharan African countries. This is to avoid double jeopardy consequent upon misdiagnosis on unidentified positive cases serving as pool reservoir for the insect vector and cyclical infection and re-infection of the populace.
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Affiliation(s)
- Olalere Shittu
- Parasitology Unit, Department of Zoology, University of Ilorin, Ilorin, Nigeria
| | | | - Olusola Ajibaye
- Biochemistry and Nutrition Unit, Nigeria Institute of Medical Research, Lagos, Nigeria
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12
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Willie N, Mehlotra RK, Howes RE, Rakotomanga TA, Ramboarina S, Ratsimbasoa AC, Zimmerman PA. Insights into the Performance of SD Bioline Malaria Ag P.f/Pan Rapid Diagnostic Test and Plasmodium falciparum Histidine-Rich Protein 2 Gene Variation in Madagascar. Am J Trop Med Hyg 2018; 98:1683-1691. [PMID: 29557337 DOI: 10.4269/ajtmh.17-0845] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Plasmodium falciparum histidine-rich protein 2 (PfHRP2) forms the basis of many current malaria rapid diagnostic tests (RDTs). However, the parasites lacking part or all of the pfhrp2 gene do not express the PfHRP2 protein and are, therefore, not identifiable by PfHRP2-detecting RDTs. We evaluated the performance of the SD Bioline Malaria Ag P.f/Pan RDT together with pfhrp2 variation in Madagascar. Genomic DNA isolated from 260 patient blood samples were polymerase chain reaction (PCR)-amplified for the parasite 18S rRNA and pfhrp2 genes. Post-PCR ligation detection reaction-fluorescent microsphere assay (LDR-FMA) was performed for the identification of parasite species. Plasmodium falciparum histidine-rich protein 2 amplicons were sequenced. Polymerase chain reaction diagnosis of patient samples showed that 29% (75/260) were infected and P. falciparum was present in 95% (71/75) of these PCR-positive samples. Comparing RDT and P. falciparum detection by LDR-FMA, eight samples were RDT negative but P. falciparum positive (false negatives), all of which were pfhrp2 positive. The sensitivity and specificity of the RDT were 87% and 90%, respectively. Seventy-three samples were amplified for pfhrp2, from which nine randomly selected amplicons were sequenced, yielding 13 sequences. Amplification of pfhrp2, combined with RDT analysis and P. falciparum detection by LDR-FMA, showed that there was no indication of pfhrp2 deletion. Sequence analysis of pfhrp2 showed that the correlation between pfhrp2 sequence structure and RDT detection rates was unclear. Although the observed absence of pfhrp2 deletion from the samples screened here is encouraging, continued monitoring of the efficacy of the SD Bioline Malaria Ag P.f/Pan RDT for malaria diagnosis in Madagascar is warranted.
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Affiliation(s)
- Nigani Willie
- Center for Global Health and Diseases, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Rajeev K Mehlotra
- Center for Global Health and Diseases, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Rosalind E Howes
- Nuffield Department of Medicine, Oxford Big Data Institute, University of Oxford, Oxford, United Kingdom.,Center for Global Health and Diseases, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Tovonahary A Rakotomanga
- Faculty of Sciences, University of Antananarivo, Antananarivo, Madagascar.,National Malaria Control Programme, Ministry of Health, Antananarivo, Madagascar
| | - Stephanie Ramboarina
- Faculty of Sciences, University of Antananarivo, Antananarivo, Madagascar.,Center for Global Health and Diseases, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Arsène C Ratsimbasoa
- Faculty of Sciences, University of Antananarivo, Antananarivo, Madagascar.,National Malaria Control Programme, Ministry of Health, Antananarivo, Madagascar
| | - Peter A Zimmerman
- Center for Global Health and Diseases, School of Medicine, Case Western Reserve University, Cleveland, Ohio
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13
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Falade CO, Ajayi IO, Nsungwa-Sabiiti J, Siribié M, Diarra A, Sermé L, Afonne C, Yusuf OB, Gansane Z, Jegede AS, Singlovic J, Gomes M. Malaria Rapid Diagnostic Tests and Malaria Microscopy for Guiding Malaria Treatment of Uncomplicated Fevers in Nigeria and Prereferral Cases in 3 African Countries. Clin Infect Dis 2018; 63:S290-S297. [PMID: 27941107 PMCID: PMC5146700 DOI: 10.1093/cid/ciw628] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Background. The World Health Organization recommends that malaria treatment be based on demonstration of the infecting Plasmodium parasite specie. Malaria rapid diagnostic tests (RDTs) are recommended at community points of care because they are accurate and rapid. We report on parasitological results in a malaria study in selected rural communities in 3 African countries. Methods. In Nigeria, community health workers (CHWs) performed RDTs (SD-Bioline) and thick blood smears on all children suspected to have malaria. Malaria RDT-positive children able to swallow received artemisinin-based combination therapy (Coartem). In all countries, children unable to take oral drugs received prereferral rectal artesunate irrespective of RDT result and were referred to the nearest health facility. Thick blood smears and RDTs were usually taken at hospital admission. In Nigeria and Burkina Faso, RDT cassettes and blood smears were re-read by an experienced investigator at study end. Results. Trained CHWs enrolled 2148 children in Nigeria. Complete parasitological data of 1860 (86.6%) enrollees were analyzed. The mean age of enrollees was 30.4 ± 15.7 months. The prevalence of malaria parasitemia in the study population was 77.8% (1447/1860), 77.6% (1439/1855), and 54.1% (862/1593) by RDT performed by CHWs vs an expert clinical research assistant vs microscopy (gold standard), respectively. Geometric mean parasite density was 6946/µL (range, 40–436 450/µL). There were 49 cases of RDT false-negative results with a parasite density range of 40–54 059/µL. False-negative RDT results with high parasitemia could be due to non-falciparum infection or result from a prozone effect. Sensitivity and specificity of SD-Bioline RDT results as read by CHWs were 94.3% and 41.6%, respectively, while the negative and positive predictive values were 86.1% and 65.6%, respectively. The level of agreement in RDT reading by the CHWs and experienced research staff was 86.04% and κ statistic of 0.60. The malaria parasite positivity rate by RDT and microscopy among children with danger signs in the 3 countries was 67.9% and 41.8%, respectively. Conclusions. RDTs are useful in guiding malaria management and were successfully used for diagnosis by trained CHWs. However, false-negative RDT results were identified and can undermine confidence in results and control efforts.
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Affiliation(s)
| | - IkeOluwapo O Ajayi
- Department of Epidemiology and Medical Statistics, College of Medicine, University of Ibadan, Nigeria
| | | | | | - Amidou Diarra
- Groupe de Recherche Action en Santé, Ouagadougou, Burkina Faso
| | - Luc Sermé
- Groupe de Recherche Action en Santé, Ouagadougou, Burkina Faso
| | - Chinenye Afonne
- Epidemiology and Biostatistics Research Unit, Institute of Advanced Medical Research and Training, College of Medicine
| | - Oyindamola B Yusuf
- Department of Epidemiology and Medical Statistics, College of Medicine, University of Ibadan, Nigeria
| | - Zakaria Gansane
- Groupe de Recherche Action en Santé, Ouagadougou, Burkina Faso
| | - Ayodele S Jegede
- Department of Sociology, Faculty of Social Sciences, University of Ibadan, Nigeria
| | - Jan Singlovic
- UNICEF/UNDP/World Bank/WHO/Special Programme for Research & Training in Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Melba Gomes
- UNICEF/UNDP/World Bank/WHO/Special Programme for Research & Training in Tropical Diseases, World Health Organization, Geneva, Switzerland
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14
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Samal AG, Behera PK, Mohanty AK, Satpathi S, Kumar A, Panda RR, Minz AM, Mohanty S, Samal A, Van Der Pluijm RW. The sensitivity and specificity of a urine based Rapid Diagnostic Test for the diagnosis of plasmodium falciparum in a malaria endemic area in Odisha, India. Pathog Glob Health 2017; 111:383-387. [PMID: 29053059 DOI: 10.1080/20477724.2017.1380945] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
BACKGROUND Rapid and accurate diagnosis is crucial in the treatment of malaria. Rapid Diagnostic Tests (RDTs) using blood have been recommended by the WHO as an acceptable method for the diagnosis of malaria. RDTs provide results quickly, is simple to use and easy to interpret. However, its use requires collection of blood by skin puncture. Hence the aim of the pilot study is to explore the sensitivity and specificity of RDTs using urine (collected non-invasively) for diagnosis of Plasmodium falciparum malaria and to assess the relation between parasite density in blood with HRP-2 Ag detection in urine. MATERIAL AND METHOD All fever cases admitted to Ispat General Hospital (IGH) Rourkela, India, during June 2012-March 2013 with a clinical diagnosis of malaria were examined for the presence of asexual forms of P. falciparum in peripheral blood smears. All smear positive febrile patients who met the eligibility criteria were enrolled. Smear negative fever cases were enrolled as control cases. RDTs were performed using both urine and blood samples by using commercially available blood specific kits. RESULTS Sixty blood smear positive cases and 51 febrile blood smear negative cases were enrolled. Sensitivity and specificity of RDT urine were 86.67% (95%CI:75.83-93.09) and 94.12% (95%CI:84.08-97.98) respectively whereas those of RDT blood were 91.67% (95% CI: 81.93-96.39) and 98.04% (95% CI 89.7-99.65). The sensitivity of both RDT urine as well as RDT blood were found to be dependent on the level of parasitemia. CONCLUSION Results of this study are promising. Larger studies are needed to assess whether RDTs using urine could serve as a practical, reliable method for the detection of P. falciparum in a non-invasive manner where invasive blood taking is less feasible.
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Affiliation(s)
- Ajit Gopal Samal
- a Department of Surgery , Hi-Tech Medical College Rourkela , Rourkela , India
| | | | - Akshay Kumar Mohanty
- c Infectious Disease Biology Unit , Institute of Life Sciences , Bhubaneswar , India
| | | | - Abhishek Kumar
- b Department of Pathology , Ispat General Hospital , Rourkela , India
| | - Rabi Ratna Panda
- b Department of Pathology , Ispat General Hospital , Rourkela , India
| | - Aruna Mukti Minz
- b Department of Pathology , Ispat General Hospital , Rourkela , India
| | - Sanjib Mohanty
- b Department of Pathology , Ispat General Hospital , Rourkela , India
| | - Abhijit Samal
- d Department of Surgery , SUM Hospital , Bhubaneswar , India
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15
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Mu J, Andersen JF, Valenzuela JG, Wellems TE. High-Sensitivity Assays for Plasmodium falciparum Infection by Immuno-Polymerase Chain Reaction Detection of PfIDEh and PfLDH Antigens. J Infect Dis 2017; 216:713-722. [PMID: 28934434 DOI: 10.1093/infdis/jix369] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 07/27/2017] [Indexed: 01/26/2023] Open
Abstract
Background Rapid diagnostic tests based on Plasmodium falciparum histidine-rich protein II (PfHRP-II) and P. falciparum lactate dehydrogenase (PfLDH) antigens are widely deployed for detection of P. falciparum infection; however, these tests often miss cases of low-level parasitemia, and PfHRP-II tests can give false-negative results when P. falciparum strains do not express this antigen. Methods We screened proteomic data for highly expressed P. falciparum proteins and compared their features to those of PfHRP-II and PfLDH biomarkers. Search criteria included high levels of expression, conservation in all parasite strains, and good correlation of antigen levels with parasitemia and its clearance after drug treatment. Different assay methods were compared for sensitive detection of parasitemia in P. falciparum cultures. Results Among potential new biomarkers, a P. falciparum homolog of insulin-degrading enzyme (PfIDEh) met our search criteria. Comparative enzyme-linked immunosorbent assays with monoclonal antibodies against PfLDH or PfIDEh showed detection limits of 100-200 parasites/µL and 200-400 parasites/µL, respectively. Detection was dramatically improved by use of real-time immuno-polymerase chain reaction (PCR), to parasitemia limits of 0.02 parasite/µL and 0.78 parasite/µL in PfLDH- and PfIDEh-based assays, respectively. Conclusions The ability of PfLDH- or PfIDEh-based immuno-PCR assays to detect <1 parasite/µL suggests that improvements of bound antibody sensor technology may greatly increase the sensitivity of malaria rapid diagnostic tests.
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Affiliation(s)
- Jianbing Mu
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
| | - John F Andersen
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
| | - Jesus G Valenzuela
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
| | - Thomas E Wellems
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
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16
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Park GS, Opoka RO, Shabani E, Wypyszynski A, Hanisch B, John CC. Plasmodium falciparum Histidine-Rich Protein-2 Plasma Concentrations Are Higher in Retinopathy-Negative Cerebral Malaria Than in Severe Malarial Anemia. Open Forum Infect Dis 2017; 4:ofx151. [PMID: 28948179 PMCID: PMC5597884 DOI: 10.1093/ofid/ofx151] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 07/14/2017] [Indexed: 11/14/2022] Open
Abstract
Background Malaria retinopathy has been proposed as marker of “true” cerebral malaria (CM), ie, coma due to Plasmodium falciparum vs coma due to other causes, with incidental P falciparum parasitemia. Plasma P falciparum histidine-rich protein-2 (PfHRP2) concentrations distinguish retinopathy-positive (RP) from retinopathy-negative (RN) CM but have not been compared between RN CM and other forms of severe malaria or asymptomatic parasitemia (AP). Methods We compared plasma PfHRP2 concentrations in 260 children with CM (247 examined for retinopathy), 228 children with severe malarial anemia (SMA), and 30 community children with AP. Results Plasmodium falciparum HRP2 concentrations were higher in children with RP CM than RN CM (P = .006), with an area under the receiver operating characteristic curve of 0.61 (95% confidence interval, 0.53–0.68). Plasmodium falciparum HRP2 concentrations and sequestered parasite biomass were higher in RN CM than SMA (both P < .03) or AP (both P < .001). Conclusions Plasmodium falciparum HRP2 concentrations are higher in children with RN CM than in children with SMA or AP, suggesting that P falciparum is involved in disease pathogenesis in children with CM. Plasmodium falciparum HRP2 concentrations may provide a more feasible and consistent assessment of the contribution of P falciparum to severe disease than malaria retinopathy.
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Affiliation(s)
- Gregory S Park
- Department of Pediatrics, University of Minnesota Medical School, Minneapolis
| | - Robert O Opoka
- Makerere University College of Health Sciences, Kampala, Uganda
| | - Estela Shabani
- Department of Pediatrics, University of Minnesota Medical School, Minneapolis.,Ryan White Center for Pediatric Infectious Diseases and Global Health, Indiana University School of Medicine, Indianapolis
| | - Alexis Wypyszynski
- Department of Pediatrics, University of Minnesota Medical School, Minneapolis
| | - Benjamin Hanisch
- Division of Pediatric Infectious Diseases, Children's National Medical Center, Washington, District of Columbia
| | - Chandy C John
- Department of Pediatrics, University of Minnesota Medical School, Minneapolis.,Ryan White Center for Pediatric Infectious Diseases and Global Health, Indiana University School of Medicine, Indianapolis
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17
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Ndour PA, Larréché S, Mouri O, Argy N, Gay F, Roussel C, Jauréguiberry S, Perillaud C, Langui D, Biligui S, Chartrel N, Mérens A, Kendjo E, Ghose A, Hassan MMU, Hossain MA, Kingston HWF, Plewes K, Dondorp AM, Danis M, Houzé S, Bonnefoy S, Thellier M, Woodrow CJ, Buffet PA. Measuring thePlasmodium falciparumHRP2 protein in blood from artesunate-treated malaria patients predicts post-artesunate delayed hemolysis. Sci Transl Med 2017; 9:9/397/eaaf9377. [DOI: 10.1126/scitranslmed.aaf9377] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Revised: 11/02/2016] [Accepted: 03/28/2017] [Indexed: 01/09/2023]
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18
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Pal P, Balaban AE, Diamond MS, Sinnis P, Klein RS, Goldberg DE. Plasmodium falciparum histidine-rich protein II causes vascular leakage and exacerbates experimental cerebral malaria in mice. PLoS One 2017; 12:e0177142. [PMID: 28475625 PMCID: PMC5419595 DOI: 10.1371/journal.pone.0177142] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 04/21/2017] [Indexed: 12/21/2022] Open
Abstract
A devastating complication of Plasmodium falciparum infection is cerebral malaria, in which vascular leakage and cerebral swelling lead to coma and often death. P. falciparum produces a protein called histidine-rich protein II (HRPII) that accumulates to high levels in the bloodstream of patients and serves as a diagnostic and prognostic marker for falciparum malaria. Using a human cerebral microvascular endothelial barrier model, we previously found that HRPII activates the endothelial cell inflammasome, resulting in decreased integrity of tight junctions and increased endothelial barrier permeability. Here, we report that intravenous administration of HRPII induced blood-brain barrier leakage in uninfected mice. Furthermore, HRPII infusion in P. berghei-infected mice increased early mortality from experimental cerebral malaria. These data support the hypothesis that HRPII is a virulence factor that contributes to cerebral malaria by compromising the integrity of the blood-brain barrier.
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Affiliation(s)
- Priya Pal
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St Louis, Missouri, United States of America
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - Amanda E. Balaban
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Michael S. Diamond
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St Louis, Missouri, United States of America
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, Missouri, United States of America
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - Photini Sinnis
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Robyn S. Klein
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St Louis, Missouri, United States of America
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, Missouri, United States of America
- Department of Neurobiology, Washington University School of Medicine, St Louis, Missouri, United States of America
| | - Daniel E. Goldberg
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St Louis, Missouri, United States of America
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, Missouri, United States of America
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Rogier E, Plucinski M, Lucchi N, Mace K, Chang M, Lemoine JF, Candrinho B, Colborn J, Dimbu R, Fortes F, Udhayakumar V, Barnwell J. Bead-based immunoassay allows sub-picogram detection of histidine-rich protein 2 from Plasmodium falciparum and estimates reliability of malaria rapid diagnostic tests. PLoS One 2017; 12:e0172139. [PMID: 28192523 PMCID: PMC5305216 DOI: 10.1371/journal.pone.0172139] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 01/31/2017] [Indexed: 11/18/2022] Open
Abstract
Detection of histidine-rich protein 2 (HRP2) from the malaria parasite Plasmodium falciparum provides evidence for active or recent infection, and is utilized for both diagnostic and surveillance purposes, but current laboratory immunoassays for HRP2 are hindered by low sensitivities and high costs. Here we present a new HRP2 immunoassay based on antigen capture through a bead-based system capable of detecting HRP2 at sub-picogram levels. The assay is highly specific and cost-effective, allowing fast processing and screening of large numbers of samples. We utilized the assay to assess results of HRP2-based rapid diagnostic tests (RDTs) in different P. falciparum transmission settings, generating estimates for true performance in the field. Through this method of external validation, HRP2 RDTs were found to perform well in the high-endemic areas of Mozambique and Angola with 86.4% and 73.9% of persons with HRP2 in their blood testing positive by RDTs, respectively, and false-positive rates of 4.3% and 0.5%. However, in the low-endemic setting of Haiti, only 14.5% of persons found to be HRP2 positive by the bead assay were RDT positive. Additionally, 62.5% of Haitians showing a positive RDT test had no detectable HRP2 by the bead assay, likely indicating that these were false positive tests. In addition to RDT validation, HRP2 biomass was assessed for the populations in these different settings, and may provide an additional metric by which to estimate P. falciparum transmission intensity and measure the impact of interventions.
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Affiliation(s)
- Eric Rogier
- The Centers for Disease Control and Prevention, Center for Global Health, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA, United States of America
- * E-mail:
| | - Mateusz Plucinski
- The Centers for Disease Control and Prevention, Center for Global Health, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA, United States of America
| | - Naomi Lucchi
- The Centers for Disease Control and Prevention, Center for Global Health, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA, United States of America
| | - Kimberly Mace
- The Centers for Disease Control and Prevention, Center for Global Health, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA, United States of America
| | - Michelle Chang
- The Centers for Disease Control and Prevention, Center for Global Health, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA, United States of America
| | - Jean Frantz Lemoine
- Programme National de Contrôle de la Malaria, Ministère de la Santé Publique et de la Population (MSPP), Port-au-Prince, Haiti
| | | | - James Colborn
- Clinton Health Access Initiative, Boston, Massachusetts, United States of America
| | - Rafael Dimbu
- National Malaria Control Program, Luanda, Angola
| | | | - Venkatachalam Udhayakumar
- The Centers for Disease Control and Prevention, Center for Global Health, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA, United States of America
| | - John Barnwell
- The Centers for Disease Control and Prevention, Center for Global Health, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA, United States of America
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Taylor DW, Bobbili N, Khadka VS, Quakyi IA, Leke RGF. Individuals living in a malaria-endemic area of Cameroon do not have an acquired antibody response to Plasmodium falciparum histidine-rich protein 2. Malar J 2017; 16:58. [PMID: 28148260 PMCID: PMC5286799 DOI: 10.1186/s12936-017-1704-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 01/19/2017] [Indexed: 12/02/2022] Open
Abstract
Background Diagnosis of Plasmodium falciparum is often based on detection of histidine-rich protein 2 (HRP2) in blood. Most HRP2-based assays have high sensitivity and specificity; however, authors have suggested that antibodies (Ab) to HRP2 could reduce assay sensitivity. This study sought to characterize the antibody response to HRP2 with respect to prevalence, class, subclass, affinity, and age distribution in Cameroonian children and adults residing in an area with high P. falciparum transmission. Methods Plasma samples from 181 Cameroonian children and adults who had been repeatedly exposed to P. falciparum and 112 samples from American adults who had never been exposed were tested for IgG Ab to HRP2. For comparison, Ab to the merozoite antigens MSP1, MSP2, MSP3 and the pregnancy-associated antigen VAR2CSA were measured using a multiplex bead-based assay. In addition, 81 plasma samples from slide-positive individuals were screened for IgM Ab to HRP2. Results As expected, children and adults had IgG Ab to MSP1, MSP2 and MSP3, antibody levels increased with age, and only women of child-bearing age had Ab to VAR2CSA; however, no convincing evidence was found that these individuals had an acquired antibody response to HRP2. That is, using two sources of recombinant HRP2, identical results were obtained when plasma from 110 Cameroonian adults and 112 US adults were screened for IgG Ab. Further studies showed that antibody prevalence and levels did not increase with age in Cameroonians between ages 5 and >80 years. Although a few samples from slide-positive Cameroonians had IgM values slightly above the American cut-off, it was unclear if the individuals had a true IgM response to HRP2 or if the values were due to non-specific binding from elevated immunoglobulin levels associated with infection. Data from prediction models showed a paucity of Class II T cell epitopes in HRP2. Conclusions These data support the conclusion that most individuals in malaria-endemic areas do not produce an acquired humoral response to HRP2. The absence of Ab helps explain why HRP2-based assays are able to detect nanogram amounts of HRP2 and why HRP2 continues to circulate for a long time after parasite clearance.
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Affiliation(s)
- Diane Wallace Taylor
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, 561 Ilalo Street, Honolulu, HI, 96813, USA.
| | - Naveen Bobbili
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, 561 Ilalo Street, Honolulu, HI, 96813, USA
| | - Vedbar S Khadka
- Office of Biostatistics & Quantitative Health Sciences, John A. Burns School of Medicine, University of Hawaii at Manoa, 561 Ilalo Street, Honolulu, HI, 96813, USA
| | - Isabella A Quakyi
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, College of Health Sciences, University of Ghana, Legon, P.O. Box LG 13, Accra, Ghana
| | - Rose G F Leke
- Faculty of Medicine and Biomedical Sciences, Biotechnology Center, University of Yaoundé I, Yaoundé, Cameroon
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Papa Mze N, Ahouidi AD, Diedhiou CK, Silai R, Diallo M, Ndiaye D, Sembene M, Mboup S. Distribution of Plasmodium species on the island of Grande Comore on the basis of DNA extracted from rapid diagnostic tests. Parasite 2016; 23:34. [PMID: 27561250 PMCID: PMC5000577 DOI: 10.1051/parasite/2016034] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 07/23/2016] [Indexed: 11/25/2022] Open
Abstract
In the Union of Comoros, interventions for combating malaria have contributed to a spectacular decrease in the prevalence of the disease. We studied the current distribution of Plasmodium species on the island of Grande Comore using nested PCR. The rapid diagnostic tests (RDTs) currently used in the Comoros are able to identify Plasmodium falciparum but no other Plasmodium species. In this study, we tested 211 RDTs (158 positive and 53 negative). Among the 158 positive RDTs, 22 were positive for HRP2, 3 were positive only for pLDH, and 133 were positive for HRP2 and pLDH. DNA was extracted from a proximal part of the nitrocellulose membrane of RDTs. A total of 159 samples were positive by nested PCR. Of those, 156 (98.11%) were positive for P. falciparum, 2 (1.25%) were positive for P. vivaxI, and 1 (0.62%) was positive for P. malariae. None of the samples were positive for P. ovale. Our results show that P. falciparum is still the most dominant species on the island of Grande Comore, but P. vivax and P. malariae are present at a low prevalence.
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Affiliation(s)
- Nasserdine Papa Mze
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Laboratory of Bacteriology-Virology, Hospital Aristide le Dantec Dakar BP 7325 Senegal
| | - Ambroise D. Ahouidi
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Laboratory of Bacteriology-Virology, Hospital Aristide le Dantec Dakar BP 7325 Senegal
| | - Cyrille K. Diedhiou
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Laboratory of Bacteriology-Virology, Hospital Aristide le Dantec Dakar BP 7325 Senegal
| | - Rahamatou Silai
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Laboratory of National Malaria Control Program Moroni Comoros
| | - Mouhamadou Diallo
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Laboratory of Bacteriology-Virology, Hospital Aristide le Dantec Dakar BP 7325 Senegal
| | - Daouda Ndiaye
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Laboratory of Parasitology and Mycology, Faculty of Medicine and Pharmacy, Cheikh Anta Diop University BP 5005
Dakar Senegal
| | - Mbacké Sembene
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Faculty of Science and Technology, Department of Animal Biology, Cheikh Anta Diop University Dakar Senegal
| | - Souleymane Mboup
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Laboratory of Bacteriology-Virology, Hospital Aristide le Dantec Dakar BP 7325 Senegal
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Zainudin NS, Othman N, Muhi J, Abdu Sani AA, Noordin R. Mature Erythrocyte Surface Antigen Protein Identified in the Serum of Plasmodium falciparum-Infected Patients. Am J Trop Med Hyg 2015; 93:1268-73. [PMID: 26392156 DOI: 10.4269/ajtmh.15-0333] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 08/06/2015] [Indexed: 11/07/2022] Open
Abstract
This study was performed to identify circulating Plasmodium falciparum proteins in patient serum, which may be useful as diagnostic markers. Depletion of highly abundant proteins from each pooled serum sample obtained from P. falciparum-infected patients and healthy individuals was performed using the Proteoseek Antibody-Based Albumin/IgG Removal Kit (Thermo Scientific, Rockford, IL). In analysis 1, the depleted serum was analyzed directly by NanoLC-MS/MS. In analysis 2, the depleted serum was separated by two-dimensional electrophoresis followed by western blot analysis. Subsequently, the selected band was analyzed by NanoLC-MS/MS. The result of analysis 1 revealed the presence of two mature erythrocyte surface antigen (MESA) proteins and chloroquine resistance transporter protein (PfCRT). In addition, analysis 2 revealed an antigenic 75-kDa band when the membrane was probed with purified IgG from the pooled serum obtained from P. falciparum-infected patients. MS/MS analysis of this protein band revealed fragments of P. falciparum MESA proteins. Thus, in this study, two different analyses revealed the presence of Plasmodium MESA protein in pooled serum from malaria patients; thus, this protein should be further investigated to determine its usefulness as a diagnostic marker.
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Affiliation(s)
- Nurul Shazalina Zainudin
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Penang, Malaysia; Kuching Health Office, Ministry of Health, Kuching, Sarawak, Malaysia; Malaysia Genome Institute, Jalan Bangi, 43000 Kajang, Selangor, Malaysia
| | - Nurulhasanah Othman
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Penang, Malaysia; Kuching Health Office, Ministry of Health, Kuching, Sarawak, Malaysia; Malaysia Genome Institute, Jalan Bangi, 43000 Kajang, Selangor, Malaysia
| | - Jamail Muhi
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Penang, Malaysia; Kuching Health Office, Ministry of Health, Kuching, Sarawak, Malaysia; Malaysia Genome Institute, Jalan Bangi, 43000 Kajang, Selangor, Malaysia
| | - Asmahani Azira Abdu Sani
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Penang, Malaysia; Kuching Health Office, Ministry of Health, Kuching, Sarawak, Malaysia; Malaysia Genome Institute, Jalan Bangi, 43000 Kajang, Selangor, Malaysia
| | - Rahmah Noordin
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Penang, Malaysia; Kuching Health Office, Ministry of Health, Kuching, Sarawak, Malaysia; Malaysia Genome Institute, Jalan Bangi, 43000 Kajang, Selangor, Malaysia
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Oyeyemi OT, Ogunlade AF, Oyewole IO. Comparative Assessment of Microscopy and Rapid Diagnostic Test (RDT) as Malaria Diagnostic Tools. ACTA ACUST UNITED AC 2015. [DOI: 10.3923/jp.2015.120.126] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Ho MF, Baker J, Lee N, Luchavez J, Ariey F, Nhem S, Oyibo W, Bell D, González I, Chiodini P, Gatton ML, Cheng Q, McCarthy JS. Circulating antibodies against Plasmodium falciparum histidine-rich proteins 2 interfere with antigen detection by rapid diagnostic tests. Malar J 2014; 13:480. [PMID: 25481825 PMCID: PMC4295572 DOI: 10.1186/1475-2875-13-480] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 10/25/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Rapid diagnostic tests (RDTs) for detection of Plasmodium falciparum infection that target P. falciparum histidine-rich protein 2 (PfHRP2), a protein that circulates in the blood of patients infected with this species of malaria, are widely used to guide case management. Understanding determinants of PfHRP2 availability in circulation is therefore essential to understanding the performance of PfHRP2-detecting RDTs. METHODS The possibility that pre-formed host anti-PfHRP2 antibodies may block target antigen detection, thereby causing false negative test results was investigated in this study. RESULTS Anti-PfHRP2 antibodies were detected in 19/75 (25%) of plasma samples collected from patients with acute malaria from Cambodia, Nigeria and the Philippines, as well as in 3/28 (10.7%) asymptomatic Solomon Islands residents. Pre-incubation of plasma samples from subjects with high-titre anti-PfHRP2 antibodies with soluble PfHRP2 blocked the detection of the target antigen on two of the three brands of RDTs tested, leading to false negative results. Pre-incubation of the plasma with intact parasitized erythrocytes resulted in a reduction of band intensity at the highest parasite density, and a reduction of lower detection threshold by ten-fold on all three brands of RDTs tested. CONCLUSIONS These observations indicate possible reduced sensitivity for diagnosis of P. falciparum malaria using PfHRP2-detecting RDTs among people with high levels of specific antibodies and low density infection, as well as possible interference with tests configured to detect soluble PfHRP2 in saliva or urine samples. Further investigations are required to assess the impact of pre-formed anti-PfHRP2 antibodies on RDT performance in different transmission settings.
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Oguonu T, Shu E, Ezeonwu BU, Lige B, Derrick A, Umeh RE, Agbo E. The performance evaluation of a urine malaria test (UMT) kit for the diagnosis of malaria in individuals with fever in south-east Nigeria: cross-sectional analytical study. Malar J 2014; 13:403. [PMID: 25316216 PMCID: PMC4203939 DOI: 10.1186/1475-2875-13-403] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 10/09/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Accurate rapid diagnosis is one of the important steps in the effort to reduce morbidity and mortality of malaria. Blood-specific malaria rapid diagnostic tests (RDTs) are currently in use but other body fluid specific diagnostic test kits are being developed. The aim of the present study was to evaluate the performance characteristics of a one-step Urine Malaria Test™ (UMT) dipstick in detecting Plasmodium falciparum HRP2, a poly-histidine antigen in urine of febrile patients for malaria diagnosis. METHODS This was an observational study in which a urine-based malaria test kit was used in malaria diagnosis in a normal field setting. Two hundred and three individuals who presented with fever (≥37.5°C) at seven outpatient clinics in Enugu State during periods of high and low transmission seasons in Southeastern Nigeria were enrolled. Matched samples of urine and blood of consecutively enrolled subjects were tested with UMT and blood smear microscopy. RESULTS With the blood smear microscopy as standard, the disease prevalence was 41.2% and sensitivity for the UMT was 83.75% (CI: 73.81 to 91.95%, Kappa 0.665, p =0.001). The UMT had an LLD of 120 parasites/μl but the sensitivity at parasite density less than ≤200 parasites/μl was 50% and 89.71% at density ≥201 parasites/μl with specificity of 83.48%. The positive and negative predictive values were 77.91% and 88.07%, respectively. CONCLUSION The UMT showed moderate level of sensitivity compared with blood smear microscopy. The test kit requires further improvement on its sensitivity in order to be deployable for field use in malaria endemic regions.
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Affiliation(s)
- Tagbo Oguonu
- />Department of Pediatrics, University of Nigeria Teaching Hospital, Enugu, Nigeria
- />Consortium for Health Research and Advanced Training, College of Medicine University of Nigeria Enugu Campus, Enugu, Nigeria
| | - Elvis Shu
- />Consortium for Health Research and Advanced Training, College of Medicine University of Nigeria Enugu Campus, Enugu, Nigeria
| | | | - Bao Lige
- />Fyodor Biotechnologies Inc, 800-West Baltimore Street, Baltimore, MD 21201 USA
| | - Anne Derrick
- />Fyodor Biotechnologies Inc, 800-West Baltimore Street, Baltimore, MD 21201 USA
| | - Rich E Umeh
- />Consortium for Health Research and Advanced Training, College of Medicine University of Nigeria Enugu Campus, Enugu, Nigeria
| | - Eddy Agbo
- />Fyodor Biotechnologies Inc, 800-West Baltimore Street, Baltimore, MD 21201 USA
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Djallé D, Gody JC, Moyen JM, Tekpa G, Ipero J, Madji N, Breurec S, Manirakiza A. Performance of Paracheck™-Pf, SD Bioline malaria Ag-Pf and SD Bioline malaria Ag-Pf/pan for diagnosis of falciparum malaria in the Central African Republic. BMC Infect Dis 2014; 14:109. [PMID: 24568311 PMCID: PMC3938899 DOI: 10.1186/1471-2334-14-109] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 02/20/2014] [Indexed: 11/17/2022] Open
Abstract
Background Rapid diagnostic tests (RDTs) are the current complement to microscopy for ensuring prompt malaria treatment. We determined the performance of three candidate RDTs (Paracheck™-Pf, SD Bioline malaria Ag-Pf and SD Bioline malaria Ag-Pf/pan) for rapid diagnosis of malaria in the Central African Republic. Methods Blood samples from consecutive febrile patients who attended for laboratory analysis of malaria at the three main health centres of Bangui were screened by microscopy and the RDTs. Two reference standards were used to assess the performance of the RDTs: microscopy and, a combination of microscopy plus nested PCR for slides reported as negative, on the assumption that negative results by microscopy were due to sub-patent parasitaemia. Results We analysed 436 samples. Using the combined reference standard of microscopy + PCR, the sensitivity of Paracheck™-Pf was 85.7% (95% CI, 80.8–89.8%), that of SD Bioline Ag-Pf was 85.4% (95% CI, 80.5–90.7%), and that of SD Bioline Ag-Pf/pan was 88.2% (95% CI, 83.2–92.0%). The tests performed less well in cases of low parasitaemia; however, the sensitivity was > 95% at > 500 parasites/μl. Conclusions Overall, SD Bioline malaria Ag-Pf and SD Bioline malaria Ag-Pf/pan performed slightly better than Paracheck™-Pf. Use of RDTs with reinforced microscopy practice and laboratory quality assurance should improve malaria treatment in the Central African Republic.
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Golassa L, Enweji N, Erko B, Aseffa A, Swedberg G. Detection of a substantial number of sub-microscopic Plasmodium falciparum infections by polymerase chain reaction: a potential threat to malaria control and diagnosis in Ethiopia. Malar J 2013; 12:352. [PMID: 24090230 PMCID: PMC3850638 DOI: 10.1186/1475-2875-12-352] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 09/18/2013] [Indexed: 12/05/2022] Open
Abstract
Background Prompt and effective malaria diagnosis not only alleviates individual suffering, but also decreases malaria transmission at the community level. The commonly used diagnostic methods, microscopy and rapid diagnostic tests, are usually insensitive at very low-density parasitaemia. Molecular techniques, on the other hand, allow the detection of low-level, sub-microscopic parasitaemia. This study aimed to explore the presence of sub-microscopic Plasmodium falciparum infections using polymerase chain reaction (PCR). The PCR-based parasite prevalence was compared against microscopy and rapid diagnostic test (RDT). Methods This study used 1,453 blood samples collected from clinical patients and sub-clinical subjects to determine the prevalence of sub-microscopic P. falciparum carriages. Subsets of RDT and microscopy negative blood samples were tested by PCR while all RDT and microscopically confirmed P. falciparum-infected samples were subjected to PCR. Finger-prick blood samples spotted on filter paper were used for parasite genomic DNA extraction. Results The prevalence of sub-microscopic P. falciparum carriage was 19.2% (77/400) (95% CI = 15. 4–23.1). Microscopy-based prevalence of P. falciparum infection was 3.7% (54/1,453) while the prevalence was 6.9% (100/1,453) using RDT alone. Using microscopy and PCR, the estimated parasite prevalence was 20.6% if PCR were performed in 1,453 blood samples. The prevalence was estimated to be 22.7% if RDT and PCR were used. Of 54 microscopically confirmed P. falciparum-infected subjects, PCR detected 90.7% (49/54). Out of 100 RDT-confirmed P. falciparum infections; PCR detected 80.0% (80/100). The sensitivity of PCR relative to microscopy and RDT was, therefore, 90.7% and 80%, respectively. The sensitivity of microscopy and RDT relative to PCR was 16.5 (49/299) and 24.2% (80/330), respectively. The overall PCR-based prevalence of P. falciparum infection was 5.6- and 3.3 fold higher than that determined by microscopy and RDT, respectively. None of the sub-microscopic subjects had severe anaemia, though 29.4% had mild anaemia (10–11.9 g/dl). Conclusions Asymptomatic, low-density malaria infection was common in the study area and PCR may be a better tool for measuring Plasmodium prevalence than microscopy and RDT. The inadequate sensitivity of the diagnostic methods to detect substantial number of sub-microscopic parasitaemia would undoubtedly affect malaria control efforts, making reduction of transmission more difficult. RDT and microscopy-based prevalence studies and subsequent reports of reduction in malaria incidence underestimate the true pictures of P. falciparum infections in the community. PCR, on the other hand, seems to have reasonable sensitivity to detect a higher number of infected subjects with low and sub-microscopic parasite densities than RDTs or microscopy.
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Affiliation(s)
- Lemu Golassa
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia.
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Eibach D, Traore B, Bouchrik M, Coulibaly B, Coulibaly N, Siby F, Bonnot G, Bienvenu AL, Picot S. Evaluation of the malaria rapid diagnostic test VIKIA malaria Ag Pf/Pan™ in endemic and non-endemic settings. Malar J 2013; 12:188. [PMID: 23742633 PMCID: PMC3684529 DOI: 10.1186/1475-2875-12-188] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 06/03/2013] [Indexed: 11/29/2022] Open
Abstract
Background Malaria rapid diagnostic tests (RDTs) are a useful tool in endemic malaria countries, where light microscopy is not feasible. In non-endemic countries they can be used as complementary tests to provide timely results in case of microscopy inexperience. This study aims to compare the new VIKIA Malaria Ag Pf/Pan™ RDT with PCR-corrected microscopy results and the commonly used CareStart™ RDT to diagnose falciparum and non-falciparum malaria in the endemic setting of Bamako, Mali and the non-endemic setting of Lyon, France. Methods Blood samples were collected during a 12-months and six-months period in 2011 from patients suspected to have malaria in Lyon and Bamako respectively. The samples were examined by light microscopy, the VIKIA Malaria Ag Pf/Pan™ test and in Bamako additionally with the CareStart™ RDT. Discordant results were corrected by real-time PCR. Sensitivity, specificity, positive predictive value and negative predictive value were used to evaluate test performance. Results Samples of 877 patients from both sites were included. The VIKIA Malaria Ag Pf/Pan™ had a sensitivity of 98% and 96% for Plasmodium falciparum in Lyon and Bamako, respectively, performing similar to PCR-corrected microscopy. Conclusions The VIKIA Malaria Ag Pf/Pan™ performs similar to PCR-corrected microscopy for the detection of P. falciparum, making it a valuable tool in malaria endemic and non-endemic regions.
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Affiliation(s)
- Daniel Eibach
- Institut de Parasitologie et de Mycologie Médicale, Faculty of Medicine, Hospices Civils de Lyon, Lyon, France.
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Manning L, Davis TME. The mechanistic, diagnostic and prognostic utility of biomarkers in severe malaria. Biomark Med 2013; 7:363-80. [DOI: 10.2217/bmm.13.50] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Malaria remains an important global cause of severe illness and mortality. This literature review summarizes available data on how biomarkers might be applied to diagnose, prognosticate and provide mechanistic insights in patients with severe malaria. Of the large number of candidate biomarkers, only PfHRP2 has consistently demonstrated clinical utility and, when incorporated into rapid antigen detection tests, has shown diagnostic sensitivity above 95%, which is at least as good as light microscopy. As a quantitative test, PfHRP2 also shows some promise in differentiating severe malarial from non-malarial disease in areas where asymptomatic carriage of malaria parasites is common, and possibly as a tool to estimate sequestered parasite burden and subsequent mortality. Biomarkers such as pLDH and panmalarial antigen have lower sensitivity for non-falciparum malaria in rapid antigen detection tests. There is an urgent need to discover and validate better biomarkers for incorporation into rapid antigen detection tests in countries where Plasmodium vivax is a common cause of severe disease. A large number of host-derived acute-phase reactants, markers of endothelial dysfunction and immune mediators have been proposed as biomarkers. Although they have provided mechanistic insights into the immunopathology of severe malaria, their roles as clinical tools remain uncertain.
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Affiliation(s)
- Laurens Manning
- School of Medicine & Pharmacology, Fremantle Hospital & Health Service, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Timothy Mark Earls Davis
- School of Medicine & Pharmacology, Fremantle Hospital & Health Service, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
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Senn N, Rarau P, Manong D, Salib M, Siba P, Reeder JC, Rogerson SJ, Genton B, Mueller I. Effectiveness of Artemether/Lumefantrine for the Treatment of Uncomplicated Plasmodium vivax and P. falciparum Malaria in Young Children in Papua New Guinea. Clin Infect Dis 2013; 56:1413-20. [DOI: 10.1093/cid/cit068] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Ogouyèmi-Hounto A, Kinde-Gazard D, Keke C, Gonçalves E, Alapini N, Adjovi F, Adisso L, Bossou C, Denon YV, Massougbodji A. Évaluation d’un test de diagnostic rapide et d’un microscope à fluorescence portable pour le diagnostic du paludisme à Cotonou (Bénin). ACTA ACUST UNITED AC 2012; 106:27-31. [DOI: 10.1007/s13149-012-0264-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 08/28/2012] [Indexed: 10/27/2022]
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Ramutton T, Hendriksen ICE, Mwanga-Amumpaire J, Mtove G, Olaosebikan R, Tshefu AK, Onyamboko MA, Karema C, Maitland K, Gomes E, Gesase S, Reyburn H, Silamut K, Chotivanich K, Promnares K, Fanello CI, von Seidlein L, Day NPJ, White NJ, Dondorp AM, Imwong M, Woodrow CJ. Sequence variation does not confound the measurement of plasma PfHRP2 concentration in African children presenting with severe malaria. Malar J 2012; 11:276. [PMID: 22898068 PMCID: PMC3480887 DOI: 10.1186/1475-2875-11-276] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 08/13/2012] [Indexed: 11/12/2022] Open
Abstract
Background Plasmodium falciparum histidine-rich protein PFHRP2 measurement is used widely for diagnosis, and more recently for severity assessment in falciparum malaria. The Pfhrp2 gene is highly polymorphic, with deletion of the entire gene reported in both laboratory and field isolates. These issues potentially confound the interpretation of PFHRP2 measurements. Methods Studies designed to detect deletion of Pfhrp2 and its paralog Pfhrp3 were undertaken with samples from patients in seven countries contributing to the largest hospital-based severe malaria trial (AQUAMAT). The quantitative relationship between sequence polymorphism and PFHRP2 plasma concentration was examined in samples from selected sites in Mozambique and Tanzania. Results There was no evidence for deletion of either Pfhrp2 or Pfhrp3 in the 77 samples with lowest PFHRP2 plasma concentrations across the seven countries. Pfhrp2 sequence diversity was very high with no haplotypes shared among 66 samples sequenced. There was no correlation between Pfhrp2 sequence length or repeat type and PFHRP2 plasma concentration. Conclusions These findings indicate that sequence polymorphism is not a significant cause of variation in PFHRP2 concentration in plasma samples from African children. This justifies the further development of plasma PFHRP2 concentration as a method for assessing African children who may have severe falciparum malaria. The data also add to the existing evidence base supporting the use of rapid diagnostic tests based on PFHRP2 detection.
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Affiliation(s)
- Thiranut Ramutton
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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Seydel KB, Fox LL, Glover SJ, Reeves MJ, Pensulo P, Muiruri A, Mpakiza A, Molyneux ME, Taylor TE. Plasma concentrations of parasite histidine-rich protein 2 distinguish between retinopathy-positive and retinopathy-negative cerebral malaria in Malawian children. J Infect Dis 2012; 206:309-18. [PMID: 22634877 DOI: 10.1093/infdis/jis371] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Brain histology and ophthalmoscopy suggest that approximately 25% of children with World Health Organization-defined cerebral malaria (CM) have a nonmalarial cause of death. Misclassification complicates clinical care, confounds studies of association, and may obfuscate successes in malaria control. Retinopathy predicts intracerebral parasite sequestration with >90% sensitivity and specificity, but detecting retinopathy requires well-trained personnel and expensive equipment. METHODS We investigated the utility of plasma concentrations of parasite histidine-rich protein 2 (pHRP2), a Plasmodium-specific protein, as a predictor of intracerebral parasite sequestration at autopsy and of malaria retinopathy on clinical examination in patients with clinically defined CM. RESULTS In 64 autopsy cases, 47 of whom had histological evidence of sequestration, the sensitivity and specificity of a plasma pHRP2 level of >1700 ng/mL were 98% and 94%, respectively, and the area under the receiver operating characteristic (AUROC) curve was 0.98. In a separate, prospectively studied group of 101 children with clinically defined CM, of whom 71 had retinopathy, the same pHRP2 cutoff predicted retinopathy-positivity with a sensitivity of 90% and specificity of 87% (AUROC, 0.90). CONCLUSIONS Elevated plasma pHRP2 concentrations can identify Malawian children with histologically confirmed or retinopathy-positive CM and is a more field-friendly approach to confirming the diagnosis than post mortem sampling or ophthalmoscopy.
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Affiliation(s)
- Karl B Seydel
- Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre.
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Marquart L, Butterworth A, McCarthy JS, Gatton ML. Modelling the dynamics of Plasmodium falciparum histidine-rich protein 2 in human malaria to better understand malaria rapid diagnostic test performance. Malar J 2012; 11:74. [PMID: 22423618 PMCID: PMC3359291 DOI: 10.1186/1475-2875-11-74] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 03/19/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Effective diagnosis of malaria is a major component of case management. Rapid diagnostic tests (RDTs) based on Plasmodium falciparumhistidine-rich protein 2 (PfHRP2) are popular for diagnosis of this most virulent malaria infection. However, concerns have been raised about the longevity of the PfHRP2 antigenaemia following curative treatment in endemic regions. METHODS A model of PfHRP2 production and decay was developed to mimic the kinetics of PfHRP2 antigenaemia during infections. Data from two human infection studies was used to fit the model, and to investigate PfHRP2 kinetics. Four malaria RDTs were assessed in the laboratory to determine the minimum detectable concentration of PfHRP2. RESULTS Fitting of the PfHRP2 dynamics model indicated that in malaria naïve hosts, P. falciparum parasites of the 3D7 strain produce 1.4 × 10⁻¹³ g of PfHRP2 per parasite per replication cycle. The four RDTs had minimum detection thresholds between 6.9 and 27.8 ng/mL. Combining these detection thresholds with the kinetics of PfHRP2, it is predicted that as few as 8 parasites/μL may be required to maintain a positive RDT in a chronic infection. CONCLUSIONS The results of the model indicate that good quality PfHRP2-based RDTs should be able to detect parasites on the first day of symptoms, and that the persistence of the antigen will cause the tests to remain positive for at least seven days after treatment. The duration of a positive test result following curative treatment is dependent on the duration and density of parasitaemia prior to treatment and the presence and affinity of anti-PfHRP2 antibodies.
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Affiliation(s)
- Louise Marquart
- Statistics Unit, Queensland Institute of Medical Research, Herston, Australia
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Hendriksen ICE, Mwanga-Amumpaire J, von Seidlein L, Mtove G, White LJ, Olaosebikan R, Lee SJ, Tshefu AK, Woodrow C, Amos B, Karema C, Saiwaew S, Maitland K, Gomes E, Pan-Ngum W, Gesase S, Silamut K, Reyburn H, Joseph S, Chotivanich K, Fanello CI, Day NPJ, White NJ, Dondorp AM. Diagnosing severe falciparum malaria in parasitaemic African children: a prospective evaluation of plasma PfHRP2 measurement. PLoS Med 2012; 9:e1001297. [PMID: 22927801 PMCID: PMC3424256 DOI: 10.1371/journal.pmed.1001297] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 07/13/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND In African children, distinguishing severe falciparum malaria from other severe febrile illnesses with coincidental Plasmodium falciparum parasitaemia is a major challenge. P. falciparum histidine-rich protein 2 (PfHRP2) is released by mature sequestered parasites and can be used to estimate the total parasite burden. We investigated the prognostic significance of plasma PfHRP2 and used it to estimate the malaria-attributable fraction in African children diagnosed with severe malaria. METHODS AND FINDINGS Admission plasma PfHRP2 was measured prospectively in African children (from Mozambique, The Gambia, Kenya, Tanzania, Uganda, Rwanda, and the Democratic Republic of the Congo) aged 1 month to 15 years with severe febrile illness and a positive P. falciparum lactate dehydrogenase (pLDH)-based rapid test in a clinical trial comparing parenteral artesunate versus quinine (the AQUAMAT trial, ISRCTN 50258054). In 3,826 severely ill children, Plasmadium falciparum PfHRP2 was higher in patients with coma (p = 0.0209), acidosis (p<0.0001), and severe anaemia (p<0.0001). Admission geometric mean (95%CI) plasma PfHRP2 was 1,611 (1,350-1,922) ng/mL in fatal cases (n = 381) versus 1,046 (991-1,104) ng/mL in survivors (n = 3,445, p<0.0001), without differences in parasitaemia as assessed by microscopy. There was a U-shaped association between log(10) plasma PfHRP2 and risk of death. Mortality increased 20% per log(10) increase in PfHRP2 above 174 ng/mL (adjusted odds ratio [AOR] 1.21, 95%CI 1.05-1.39, p = 0.009). A mechanistic model assuming a PfHRP2-independent risk of death in non-malaria illness closely fitted the observed data and showed malaria-attributable mortality less than 50% with plasma PfHRP2≤174 ng/mL. The odds ratio (OR) for death in artesunate versus quinine-treated patients was 0.61 (95%CI 0.44-0.83, p = 0.0018) in the highest PfHRP2 tertile, whereas there was no difference in the lowest tertile (OR 1.05; 95%CI 0.69-1.61; p = 0.82). A limitation of the study is that some conclusions are drawn from a mechanistic model, which is inherently dependent on certain assumptions. However, a sensitivity analysis of the model indicated that the results were robust to a plausible range of parameter estimates. Further studies are needed to validate our findings. CONCLUSIONS Plasma PfHRP2 has prognostic significance in African children with severe falciparum malaria and provides a tool to stratify the risk of "true" severe malaria-attributable disease as opposed to other severe illnesses in parasitaemic African children.
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Affiliation(s)
- Ilse C. E. Hendriksen
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine, Churchill Hospital, University of Oxford, Oxford, United Kingdom
| | | | | | - George Mtove
- National Institute for Medical Research, Amani Centre, Tanga, Tanzania
| | - Lisa J. White
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine, Churchill Hospital, University of Oxford, Oxford, United Kingdom
| | | | - Sue J. Lee
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine, Churchill Hospital, University of Oxford, Oxford, United Kingdom
| | - Antoinette K. Tshefu
- Kinshasa School of Public Health, Kingasani Research Centre, Kinshasa, Democratic Republic of the Congo
| | - Charles Woodrow
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine, Churchill Hospital, University of Oxford, Oxford, United Kingdom
| | - Ben Amos
- Teule Hospital, Muheza, Tanzania
| | - Corine Karema
- Malaria Control Program, Ministry of Health, Kigali, Rwanda
| | - Somporn Saiwaew
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Kathryn Maitland
- Kenya Medical Research Institute (KEMRI)–Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Wirichada Pan-Ngum
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Samwel Gesase
- National Institute for Medical Research, Tanga Medical Research Centre, Tanga, Tanzania
| | - Kamolrat Silamut
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Hugh Reyburn
- London School of Tropical Medicine & Hygiene, London, United Kingdom
| | - Sarah Joseph
- Medical Research Council, London, United Kingdom
| | - Kesinee Chotivanich
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Caterina I. Fanello
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine, Churchill Hospital, University of Oxford, Oxford, United Kingdom
| | - Nicholas P. J. Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine, Churchill Hospital, University of Oxford, Oxford, United Kingdom
| | - Nicholas J. White
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine, Churchill Hospital, University of Oxford, Oxford, United Kingdom
| | - Arjen M. Dondorp
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine, Churchill Hospital, University of Oxford, Oxford, United Kingdom
- * E-mail:
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Baker J, Gatton ML, Peters J, Ho MF, McCarthy JS, Cheng Q. Transcription and expression of Plasmodium falciparum histidine-rich proteins in different stages and strains: implications for rapid diagnostic tests. PLoS One 2011; 6:e22593. [PMID: 21799910 PMCID: PMC3142190 DOI: 10.1371/journal.pone.0022593] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Accepted: 06/29/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Although rapid diagnostic tests (RDTs) for Plasmodium falciparum infection that target histidine rich protein 2 (PfHRP2) are generally sensitive, their performance has been reported to be variable. One possible explanation for variable test performance is differences in expression level of PfHRP in different parasite isolates. METHODS Total RNA and protein were extracted from synchronised cultures of 7 P. falciparum lines over 5 time points of the life cycle, and from synchronised ring stages of 10 falciparum lines. Using quantitative real-time polymerase chain reaction, Western blot analysis and ELISA we investigated variations in the transcription and protein levels of pfhrp2, pfhrp3 and PfHRP respectively in the different parasite lines, over the parasite intraerythrocytic life cycle. RESULTS Transcription of pfhrp2 and pfhrp3 in different parasite lines over the parasite life cycle was observed to vary relative to the control parasite K1. In some parasite lines very low transcription of these genes was observed. The peak transcription was observed in ring-stage parasites. Pfhrp2 transcription was observed to be consistently higher than pfhrp3 transcription within parasite lines. The intraerythrocytic lifecycle stage at which the peak level of protein was present varied across strains. Total protein levels were more constant relative to total mRNA transcription, however a maximum 24 fold difference in expression at ring-stage parasites relative to the K1 strain was observed. CONCLUSIONS The levels of transcription of pfhrp2 and pfhrp3, and protein expression of PfHRP varied between different P. falciparum strains. This variation may impact on the detection sensitivity of PfHRP2-detecting RDTs.
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Affiliation(s)
- Joanne Baker
- Department of Drug Resistance and Diagnostics, Australian Army Malaria Institute, Gallipoli Barracks, Enoggera, Queensland, Australia
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Mtove G, Nadjm B, Amos B, Hendriksen ICE, Muro F, Reyburn H. Use of an HRP2-based rapid diagnostic test to guide treatment of children admitted to hospital in a malaria-endemic area of north-east Tanzania. Trop Med Int Health 2011; 16:545-50. [PMID: 21320243 PMCID: PMC3469736 DOI: 10.1111/j.1365-3156.2011.02737.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Objective To compare the performance of the Paracheck™ rapid diagnostic test (RDT) with microscopy for diagnosing malaria in hospitalised children. Methods Children aged between 2 months and 13 years with fever were enrolled in the study over 1 year. A standard clinical history and examination were recorded and blood drawn for culture, complete blood count, Paracheck™ RDT and double-read blood slide. Results Of 3639 children enrolled, 2195 (60.3%) were slide positive. The sensitivity and specificity of Paracheck were 97.5% (95% CI 96.9–98.0) and 65.3% (95% CI 63.8–66.9), respectively. There was an inverse relationship between age-specific prevalence of parasitaemia and Paracheck specificity. In logistic regression model, false-positive Paracheck results were significantly associated with pre-admission use of antimalarial drug (OR 1.44, 95% CI 1.16–1.78), absence of current fever (OR 0.64, 95% CI 0.52–0.79) and non-typhi Salmonella bacteraemia (OR 3.89. 95% CI 2.27–6.63). In spite of high sensitivity, 56/2195 (2.6%) of true infections were Paracheck negative and 8/56 (14.3%) were in patients with >50 000 parasites/μl. Conclusions Paracheck had poor specificity in diagnosing malaria in severely ill children; this was likely to be due to HRP2 persistence following recent parasite clearance. The combination of positive Paracheck and negative blood slide results identified a group of children at high risk of non-typhi Salmonella infection. While Paracheck was highly sensitive, some high-density infections were missed. For children with severe febrile illness, at least two reliable negative parasitological test results should be available to justify withholding antimalarial treatment; the optimal choice of these has yet to be identified.
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Affiliation(s)
- George Mtove
- National Institute for Medical Research, Amani Centre, Muheza, Tanzania.
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Manning L, Laman M, Stanisic D, Rosanas-Urgell A, Bona C, Teine D, Siba P, Mueller I, Davis TME. Plasma Plasmodium falciparum Histidine-Rich Protein-2 Concentrations Do Not Reflect Severity of Malaria in Papua New Guinean Children. Clin Infect Dis 2011; 52:440-6. [DOI: 10.1093/cid/ciq105] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Harris I, Sharrock WW, Bain LM, Gray KA, Bobogare A, Boaz L, Lilley K, Krause D, Vallely A, Johnson ML, Gatton ML, Shanks GD, Cheng Q. A large proportion of asymptomatic Plasmodium infections with low and sub-microscopic parasite densities in the low transmission setting of Temotu Province, Solomon Islands: challenges for malaria diagnostics in an elimination setting. Malar J 2010; 9:254. [PMID: 20822506 PMCID: PMC2944341 DOI: 10.1186/1475-2875-9-254] [Citation(s) in RCA: 229] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Accepted: 09/07/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Many countries are scaling up malaria interventions towards elimination. This transition changes demands on malaria diagnostics from diagnosing ill patients to detecting parasites in all carriers including asymptomatic infections and infections with low parasite densities. Detection methods suitable to local malaria epidemiology must be selected prior to transitioning a malaria control programme to elimination. A baseline malaria survey conducted in Temotu Province, Solomon Islands in late 2008, as the first step in a provincial malaria elimination programme, provided malaria epidemiology data and an opportunity to assess how well different diagnostic methods performed in this setting. METHODS During the survey, 9,491 blood samples were collected and examined by microscopy for Plasmodium species and density, with a subset also examined by polymerase chain reaction (PCR) and rapid diagnostic tests (RDTs). The performances of these diagnostic methods were compared. RESULTS A total of 256 samples were positive by microscopy, giving a point prevalence of 2.7%. The species distribution was 17.5% Plasmodium falciparum and 82.4% Plasmodium vivax. In this low transmission setting, only 17.8% of the P. falciparum and 2.9% of P. vivax infected subjects were febrile (≥ 38°C) at the time of the survey. A significant proportion of infections detected by microscopy, 40% and 65.6% for P. falciparum and P. vivax respectively, had parasite density below 100/μL. There was an age correlation for the proportion of parasite density below 100/μL for P. vivax infections, but not for P. falciparum infections. PCR detected substantially more infections than microscopy (point prevalence of 8.71%), indicating a large number of subjects had sub-microscopic parasitemia. The concordance between PCR and microscopy in detecting single species was greater for P. vivax (135/162) compared to P. falciparum (36/118). The malaria RDT detected the 12 microscopy and PCR positive P. falciparum, but failed to detect 12/13 microscopy and PCR positive P. vivax infections. CONCLUSION Asymptomatic malaria infections and infections with low and sub-microscopic parasite densities are highly prevalent in Temotu province where malaria transmission is low. This presents a challenge for elimination since the large proportion of the parasite reservoir will not be detected by standard active and passive case detection. Therefore effective mass screening and treatment campaigns will most likely need more sensitive assays such as a field deployable molecular based assay.
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Affiliation(s)
- Ivor Harris
- Australian Army Malaria Institute, Weary Dunlop Drive, Gallipoli Barracks Enoggera, Qld 4051, Australia
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Akpogheneta OJ, Dunyo S, Pinder M, Conway DJ. Boosting antibody responses to Plasmodium falciparum merozoite antigens in children with highly seasonal exposure to infection. Parasite Immunol 2010; 32:296-304. [PMID: 20398230 PMCID: PMC2848980 DOI: 10.1111/j.1365-3024.2009.01193.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Longitudinal cohort studies are important to describe the dynamics of naturally acquired antibody response profiles to defined Plasmodium falciparum malaria antigens relative to clinical malaria episodes. In children under 7 years of age in The Gambia, serum IgG responses were measured to P. falciparum merozoite antigens AMA1, EBA175, MSP1(19), MSP2 and crude schizont extract, over a 10-month period. Persistence of antibody responses was measured in 152 children during the dry season when there was virtually no malaria transmission, and 103 children were monitored for new episodes of clinical malaria during the subsequent wet season when transmission occurred. Children who experienced clinical malaria had lower antibody levels at the start of the study than those who remained free from malaria. Associations between dry season antibody persistence and subsequent wet season antibody levels suggested robust immunological memory responses. Mean antibody levels to all antigens were elevated by the end of the wet season in children who experienced clinical malaria; each of these children had a boosted antibody response to at least one antigen. In all children, antibody avidities were lower against MSP2 than other antigens, a difference that did not change throughout the study period or in relation to clinical malaria episodes.
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Baker J, Ho MF, Pelecanos A, Gatton M, Chen N, Abdullah S, Albertini A, Ariey F, Barnwell J, Bell D, Cunningham J, Djalle D, Echeverry DF, Gamboa D, Hii J, Kyaw MP, Luchavez J, Membi C, Menard D, Murillo C, Nhem S, Ogutu B, Onyor P, Oyibo W, Wang SQ, McCarthy J, Cheng Q. Global sequence variation in the histidine-rich proteins 2 and 3 of Plasmodium falciparum: implications for the performance of malaria rapid diagnostic tests. Malar J 2010; 9:129. [PMID: 20470441 PMCID: PMC2893195 DOI: 10.1186/1475-2875-9-129] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Accepted: 05/17/2010] [Indexed: 11/20/2022] Open
Abstract
Background Accurate diagnosis is essential for prompt and appropriate treatment of malaria. While rapid diagnostic tests (RDTs) offer great potential to improve malaria diagnosis, the sensitivity of RDTs has been reported to be highly variable. One possible factor contributing to variable test performance is the diversity of parasite antigens. This is of particular concern for Plasmodium falciparum histidine-rich protein 2 (PfHRP2)-detecting RDTs since PfHRP2 has been reported to be highly variable in isolates of the Asia-Pacific region. Methods The pfhrp2 exon 2 fragment from 458 isolates of P. falciparum collected from 38 countries was amplified and sequenced. For a subset of 80 isolates, the exon 2 fragment of histidine-rich protein 3 (pfhrp3) was also amplified and sequenced. DNA sequence and statistical analysis of the variation observed in these genes was conducted. The potential impact of the pfhrp2 variation on RDT detection rates was examined by analysing the relationship between sequence characteristics of this gene and the results of the WHO product testing of malaria RDTs: Round 1 (2008), for 34 PfHRP2-detecting RDTs. Results Sequence analysis revealed extensive variations in the number and arrangement of various repeats encoded by the genes in parasite populations world-wide. However, no statistically robust correlation between gene structure and RDT detection rate for P. falciparum parasites at 200 parasites per microlitre was identified. Conclusions The results suggest that despite extreme sequence variation, diversity of PfHRP2 does not appear to be a major cause of RDT sensitivity variation.
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Affiliation(s)
- Joanne Baker
- Department of Drug Resistance and Diagnostics, Australian Army Malaria Institute, Brisbane, Australia.
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Abeku TA, Kristan M, Jones C, Beard J, Mueller DH, Okia M, Rapuoda B, Greenwood B, Cox J. Determinants of the accuracy of rapid diagnostic tests in malaria case management: evidence from low and moderate transmission settings in the East African highlands. Malar J 2008; 7:202. [PMID: 18834523 PMCID: PMC2571107 DOI: 10.1186/1475-2875-7-202] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2008] [Accepted: 10/03/2008] [Indexed: 11/16/2022] Open
Abstract
Background The accuracy of malaria diagnosis has received renewed interest in recent years due to changes in treatment policies in favour of relatively high-cost artemisinin-based combination therapies. The use of rapid diagnostic tests (RDTs) based on histidine-rich protein 2 (HRP2) synthesized by Plasmodium falciparum has been widely advocated to save costs and to minimize inappropriate treatment of non-malarial febrile illnesses. HRP2-based RDTs are highly sensitive and stable; however, their specificity is a cause for concern, particularly in areas of intense malaria transmission due to persistence of HRP2 antigens from previous infections. Methods In this study, 78,454 clinically diagnosed malaria patients were tested using HRP2-based RDTs over a period of approximately four years in four highland sites in Kenya and Uganda representing hypoendemic to mesoendemic settings. In addition, the utility of the tests was evaluated in comparison with expert microscopy for disease management in 2,241 subjects in two sites with different endemicity levels over four months. Results RDT positivity rates varied by season and year, indicating temporal changes in accuracy of clinical diagnosis. Compared to expert microscopy, the sensitivity, specificity, positive predictive value and negative predictive value of the RDTs in a hypoendemic site were 90.0%, 99.9%, 90.0% and 99.9%, respectively. Corresponding measures at a mesoendemic site were 91.0%, 65.0%, 71.6% and 88.1%. Although sensitivities at the two sites were broadly comparable, levels of specificity varied considerably between the sites as well as according to month of test, age of patient, and presence or absence of fever during consultation. Specificity was relatively high in older age groups and increased towards the end of the transmission season, indicating the role played by anti-HRP2 antibodies. Patients with high parasite densities were more likely to test positive with RDTs than those with low density infections. Conclusion RDTs may be effective when used in low endemicity situations, but high false positive error rates may occur in areas with moderately high transmission. Reports on specificity of RDTs and cost-effectiveness analyses on their use should be interpreted with caution as there may be wide variations in these measurements depending upon endemicity, season and the age group of patients studied.
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Affiliation(s)
- Tarekegn A Abeku
- London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
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Toovey S, Moerman F, van Gompel A. Special infectious disease risks of expatriates and long-term travelers in tropical countries. Part I: malaria. J Travel Med 2007; 14:42-9. [PMID: 17241253 DOI: 10.1111/j.1708-8305.2006.00091.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Malaria risk is dependent upon the entomological inoculation rate actually faced by the long-term traveler. Risk is cumulative, increases with duration of exposure, is greatest in rural and periurban areas, and least in urban centers. Risk may be zero in some urban centers, especially during dry seasons. Chemoprophylaxis compliance is hindered by the high adverse event rate often reported by users, is often suboptimal in expatriates, and decreases with duration of stay. Compliance with personal protection measures may also be suboptimal, and use of insecticide-treated nets and effective repellents should be encouraged. Alternative strategies to mitigate risk include seasonal chemoprophylaxis, nonuse of chemoprophylaxis with rapid treatment, self-testing, self-treatment where competent care and quality drugs are unavailable, and vector control. Choice of strategies will depend upon assessment of actual risk and likely compliance, with a combination of measures usually appropriate.
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Affiliation(s)
- Stephen Toovey
- Royal Free and University College Medical School, London, UK.
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Biswas S. Assessment of immunometric parameters in malaria: role of enzyme immunoassay. J Immunoassay Immunochem 2006; 27:341-50. [PMID: 16981647 DOI: 10.1080/15321810600862181] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Human blood samples collected from local malaria clinics, hospitals, and by cross-sectional surveys in malaria endemic areas were tested by enzyme immunoassay for circulating malarial antigen, antimalarial antibody, and antigen-specific circulating immune complexes. The assays were done in serum and finger-prick blood absorbed on filter paper. The results obtained from the present study suggest their roles as effective immunometric indicators.
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Affiliation(s)
- Sukla Biswas
- National Institute of Malaria Research (ICMR), 22 Sham Nath Marg, Delhi 110 054, India.
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