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Bally DR, Santos SDS, Arregue DC, de Mattos MK, Suárez-Mutis MC. High Frequency of Deletions in the pfhrp2 and pfhrp3 Genes of Plasmodium falciparum in the Middle Rio Negro Region of the Brazilian Amazon. Trop Med Infect Dis 2024; 9:149. [PMID: 39058191 PMCID: PMC11281371 DOI: 10.3390/tropicalmed9070149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 06/25/2024] [Accepted: 06/28/2024] [Indexed: 07/28/2024] Open
Abstract
Several countries are reporting natural populations of P. falciparum with deletions in the pfhrp2/3 genes that can lead to false-negative results in rapid diagnostic tests. To investigate the prevalence of deletion in the pfhrp2/3 genes in the Rio Negro basin in the Brazilian Amazon and identify whether there is clinical differentiation between individuals infected by these parasites, clinical samples collected from 2003 to 2016 were analyzed from symptomatic and asymptomatic P. falciparum-infected individuals. The molecular deletion of pfhrp2 and pfhrp3 genes was evaluated using the protocols recommended by the WHO. From 82 samples used, 28 (34.2%) had a single deletion in pfhrp2, 19 (23.2%) had a single deletion in pfhrp3, 15 (18.3%) had a double deletion (pfhrp2/3), and 20 (24.4%) did not have a deletion in either gene. In total, 29.3% of individuals had an asymptomatic plasmodial infection and were 3.64 times more likely to have parasites with a double deletion (pfhrp2/3) than patients with clinical malaria (p = 0.02). The high prevalence of parasites with pfhrp2/3 deletions shows the need to implement a surveillance program in this area. Deletions in parasites may be associated with the clinical pattern of the disease in this area. More studies must be carried out to elucidate these findings.
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Affiliation(s)
- Daniela Romero Bally
- Laboratório de Doenças Parasitárias, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro 21040-900, Brazil; (D.R.B.); (S.d.S.S.); (D.C.A.); (M.K.d.M.)
- Post-Graduation Program in Tropical Medicine, Instituto Oswaldo Cruz-Fiocruz, Rio de Janeiro 21040-900, Brazil
| | - Simone da Silva Santos
- Laboratório de Doenças Parasitárias, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro 21040-900, Brazil; (D.R.B.); (S.d.S.S.); (D.C.A.); (M.K.d.M.)
| | - Diego Calafate Arregue
- Laboratório de Doenças Parasitárias, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro 21040-900, Brazil; (D.R.B.); (S.d.S.S.); (D.C.A.); (M.K.d.M.)
| | - Mariana Kelly de Mattos
- Laboratório de Doenças Parasitárias, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro 21040-900, Brazil; (D.R.B.); (S.d.S.S.); (D.C.A.); (M.K.d.M.)
| | - Martha C. Suárez-Mutis
- Laboratório de Doenças Parasitárias, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro 21040-900, Brazil; (D.R.B.); (S.d.S.S.); (D.C.A.); (M.K.d.M.)
- Post-Graduation Program in Tropical Medicine, Instituto Oswaldo Cruz-Fiocruz, Rio de Janeiro 21040-900, Brazil
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Kojom Foko LP, Eboumbou Moukoko CE, Jakhan J, Narang G, Hawadak J, Kouemo Motse FD, Pande V, Singh V. Deletions of Histidine-Rich Protein 2/3 Genes in Natural Plasmodium falciparum Populations from Cameroon and India: Role of Asymptomatic and Submicroscopic Infections. Am J Trop Med Hyg 2024; 110:1100-1109. [PMID: 38688260 PMCID: PMC11154061 DOI: 10.4269/ajtmh.23-0896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 02/29/2024] [Indexed: 05/02/2024] Open
Abstract
The bulk of malaria rapid diagnostic tests (RDTs) target histidine-rich protein 2 of Plasmodium falciparum, the deadliest malaria species. The WHO considers pfhrp2/3 deletions as one of the main threats to successful malaria control and/or elimination; as such, parasites that lack part or all of the pfhrp2 gene are missed by pfHRP2-targeting RDTs. Such deletions have been reported in several African and Asian countries, but little is known in Cameroon and India. Blood samples were collected from individuals living in four areas of Cameroon (Douala, Maroua, Mayo-Oulo, Pette) and India (Mewat, Raipur, Ranchi, Rourkela). Deletions in pfhrp2/3 genes were confirmed if samples 1) had ≥100 parasites/µL by quantitative polymerase chain reaction (PCR), 2) PCR negative for pfhrp2/3, and 3) PCR positive for at least two single-copy genes. The overall proportion of pfhrp2 and pfhrp3 deletions in Cameroon was 13.5% and 3.1%. In India, the overall proportion was 8% for pfhrp2 and 4% for pfhrp3. The overall proportions of samples with both gene deletions (pfhrp2-/3-) were 3.1% in Cameroon and 1.3% in India. In Cameroon, pfhrp2-/3+ and pfhrp2-/3- deletions were common in Maroua (P = 0.02), in asymptomatic parasitemia (P = 0.006) and submicroscopic parasitemia (P <0.0001). In both countries, pfhrp2/3 deletions, including pfhrp2-/3- deletions, were mainly seen in monoclonal infections. This study outlines that double deletions that result in false negative RDTs are uncommon in our settings, and highlights the importance of active molecular surveillance for pfhrp2/3 deletions in Cameroon and India.
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Affiliation(s)
- Loick Pradel Kojom Foko
- National Institute of Malaria Research, New Delhi, India
- Department of Biotechnology, Kumaun University, Bhimtal, India
| | - Carole Else Eboumbou Moukoko
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, The University of Douala, Douala, Cameroon
- Malaria Research Unit, Centre Pasteur Cameroon, Yaoundé, Cameroon
- Laboratory of Parasitology, Mycology and Virology, Postgraduate Training Unit for Health Sciences, Postgraduate School for Pure and Applied Sciences, The University of Douala, Douala, Cameroon
| | - Jahnvi Jakhan
- National Institute of Malaria Research, New Delhi, India
| | - Geetika Narang
- National Institute of Malaria Research, New Delhi, India
| | - Joseph Hawadak
- National Institute of Malaria Research, New Delhi, India
- Department of Biotechnology, Kumaun University, Bhimtal, India
| | | | - Veena Pande
- Department of Biotechnology, Kumaun University, Bhimtal, India
| | - Vineeta Singh
- National Institute of Malaria Research, New Delhi, India
- Academy of Scientific and Innovative Research, Ghaziabad, India
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Mwanga EP, Siria DJ, Mshani IH, Mwinyi SH, Abbasi S, Jimenez MG, Wynne K, Baldini F, Babayan SA, Okumu FO. Rapid classification of epidemiologically relevant age categories of the malaria vector, Anopheles funestus. Parasit Vectors 2024; 17:143. [PMID: 38500231 PMCID: PMC10949582 DOI: 10.1186/s13071-024-06209-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 02/21/2024] [Indexed: 03/20/2024] Open
Abstract
BACKGROUND Accurately determining the age and survival probabilities of adult mosquitoes is crucial for understanding parasite transmission, evaluating the effectiveness of control interventions and assessing disease risk in communities. This study was aimed at demonstrating the rapid identification of epidemiologically relevant age categories of Anopheles funestus, a major Afro-tropical malaria vector, through the innovative combination of infrared spectroscopy and machine learning, instead of the cumbersome practice of dissecting mosquito ovaries to estimate age based on parity status. METHODS Anopheles funestus larvae were collected in rural south-eastern Tanzania and reared in an insectary. Emerging adult females were sorted by age (1-16 days old) and preserved using silica gel. Polymerase chain reaction (PCR) confirmation was conducted using DNA extracted from mosquito legs to verify the presence of An. funestus and to eliminate undesired mosquitoes. Mid-infrared spectra were obtained by scanning the heads and thoraces of the mosquitoes using an attenuated total reflection-Fourier transform infrared (ATR-FT-IR) spectrometer. The spectra (N = 2084) were divided into two epidemiologically relevant age groups: 1-9 days (young, non-infectious) and 10-16 days (old, potentially infectious). The dimensionality of the spectra was reduced using principal component analysis, and then a set of machine learning and multi-layer perceptron (MLP) models were trained using the spectra to predict the mosquito age categories. RESULTS The best-performing model, XGBoost, achieved overall accuracy of 87%, with classification accuracy of 89% for young and 84% for old An. funestus. When the most important spectral features influencing the model performance were selected to train a new model, the overall accuracy increased slightly to 89%. The MLP model, utilizing the significant spectral features, achieved higher classification accuracy of 95% and 94% for the young and old An. funestus, respectively. After dimensionality reduction, the MLP achieved 93% accuracy for both age categories. CONCLUSIONS This study shows how machine learning can quickly classify epidemiologically relevant age groups of An. funestus based on their mid-infrared spectra. Having been previously applied to An. gambiae, An. arabiensis and An. coluzzii, this demonstration on An. funestus underscores the potential of this low-cost, reagent-free technique for widespread use on all the major Afro-tropical malaria vectors. Future research should demonstrate how such machine-derived age classifications in field-collected mosquitoes correlate with malaria in human populations.
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Affiliation(s)
- Emmanuel P Mwanga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Morogoro, Tanzania.
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK.
| | - Doreen J Siria
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Morogoro, Tanzania
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Issa H Mshani
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Morogoro, Tanzania
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Sophia H Mwinyi
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Morogoro, Tanzania
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Said Abbasi
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Morogoro, Tanzania
| | - Mario Gonzalez Jimenez
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
- School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Klaas Wynne
- School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Francesco Baldini
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Simon A Babayan
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Morogoro, Tanzania
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- School of Life Science and Bioengineering, The Nelson Mandela African Institution of Science and Technology, P. O. Box 447, Arusha, Tanzania
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Agaba BB, Smith D, Travis J, Pasay C, Nabatanzi M, Arinaitwe E, Ssewanyana I, Nabadda S, Cunningham J, Kamya MR, Cheng Q. Limited threat of Plasmodium falciparum pfhrp2 and pfhrp3 gene deletion to the utility of HRP2-based malaria RDTs in Northern Uganda. Malar J 2024; 23:3. [PMID: 38167003 PMCID: PMC10759665 DOI: 10.1186/s12936-023-04830-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 12/21/2023] [Indexed: 01/05/2024] Open
Abstract
BACKGROUND Rapid diagnostic tests (RDTs) that detect Plasmodium falciparum histidine-rich protein-2 (PfHRP2) are exclusively deployed in Uganda, but deletion of the pfhrp2/3 target gene threatens their usefulness as malaria diagnosis and surveillance tools. METHODS A cross-sectional survey was conducted at 40 sites across four regions of Uganda in Acholi, Lango, W. Nile and Karamoja from March 2021 to June 2023. Symptomatic malaria suspected patients were recruited and screened with both HRP2 and pan lactate dehydrogenase (pLDH) detecting RDTs. Dried blood spots (DBS) were collected from all patients and a random subset were used for genomic analysis to confirm parasite species and pfhrp2 and pfhrp3 gene status. Plasmodium species was determined using a conventional multiplex PCR while pfhrp2 and pfhrp3 gene deletions were determined using a real-time multiplex qPCR. Expression of the HRP2 protein antigen in a subset of samples was further assessed using a ELISA. RESULTS Out of 2435 symptomatic patients tested for malaria, 1504 (61.8%) were positive on pLDH RDT. Overall, qPCR confirmed single pfhrp2 gene deletion in 1 out of 416 (0.2%) randomly selected samples that were confirmed of P. falciparum mono-infections. CONCLUSION These findings show limited threat of pfhrp2/3 gene deletions in the survey areas suggesting that HRP2 RDTs are still useful diagnostic tools for surveillance and diagnosis of P. falciparum malaria infections in symptomatic patients in this setting. Periodic genomic surveillance is warranted to monitor the frequency and trend of gene deletions and its effect on RDTs.
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Affiliation(s)
- Bosco B Agaba
- Faculty of Medicine, Department of Medical Laboratory Sciences, Mbarara University of Science and Technology, Mbarara, Uganda.
- National Malaria Control Division, Kampala, Uganda.
- London School of Hygiene and Tropical Medicine, London, UK.
- Infectious Diseases Research Collaboration, Kampala, Uganda.
| | - David Smith
- QIMR Berghofer Medical Research Institute, Kelvin Grove, QLD, Australia
- Australian Defence Force Malaria and Infectious Disease Institute, Kelvin Grove, Australia
| | - Jye Travis
- QIMR Berghofer Medical Research Institute, Kelvin Grove, QLD, Australia
- Australian Defence Force Malaria and Infectious Disease Institute, Kelvin Grove, Australia
| | - Cielo Pasay
- QIMR Berghofer Medical Research Institute, Kelvin Grove, QLD, Australia
| | | | | | - Isaac Ssewanyana
- Infectious Diseases Research Collaboration, Kampala, Uganda
- National Health Laboratory Services/Central Public Health Laboratories, Kelvin Grove, Uganda
| | - Susan Nabadda
- National Health Laboratory Services/Central Public Health Laboratories, Kelvin Grove, Uganda
| | - Jane Cunningham
- Global Malaria Programme, World Health Organization, Geneva, Switzerland
| | - Moses R Kamya
- Faculty of Medicine, Department of Medical Laboratory Sciences, Mbarara University of Science and Technology, Mbarara, Uganda
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Qin Cheng
- QIMR Berghofer Medical Research Institute, Kelvin Grove, QLD, Australia
- Australian Defence Force Malaria and Infectious Disease Institute, Kelvin Grove, Australia
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Watson OJ, Tran TNA, Zupko RJ, Symons T, Thomson R, Visser T, Rumisha S, Dzianach PA, Hathaway N, Kim I, Juliano JJ, Bailey JA, Slater H, Okell L, Gething P, Ghani A, Boni MF, Parr JB, Cunningham J. Global risk of selection and spread of Plasmodium falciparum histidine-rich protein 2 and 3 gene deletions. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2023.10.21.23297352. [PMID: 37905102 PMCID: PMC10615018 DOI: 10.1101/2023.10.21.23297352] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
In the thirteen years since the first report of pfhrp2-deleted parasites in 2010, the World Health Organization (WHO) has found that 40 of 47 countries surveyed worldwide have reported pfhrp2/3 gene deletions. Due to a high prevalence of pfhrp2/3 deletions causing false-negative HRP2 RDTs, in the last five years, Eritrea, Djibouti and Ethiopia have switched or started switching to using alternative RDTs, that target pan-specific-pLDH or P. falciparum specific-pLDH alone of in combination with HRP2. However, manufacturing of alternative RDTs has not been brought to scale and there are no WHO prequalified combination tests that use Pf-pLDH instead of HRP2 for P. falciparum detection. For these reasons, the continued spread of pfhrp2/3 deletions represents a growing public health crisis that threatens efforts to control and eliminate P. falciparum malaria. National malaria control programmes, their implementing partners and test developers desperately seek pfhrp2/3 deletion data that can inform their immediate and future resource allocation. In response, we use a mathematical modelling approach to evaluate the global risk posed by pfhrp2/3 deletions and explore scenarios for how deletions will continue to spread in Africa. We incorporate current best estimates of the prevalence of pfhrp2/3 deletions and conduct a literature review to estimate model parameters known to impact the selection of pfhrp2/3 deletions for each malaria endemic country. We identify 20 countries worldwide to prioritise for surveillance and future deployment of alternative RDT, based on quickly selecting for pfhrp2/3 deletions once established. In scenarios designed to explore the continued spread of deletions in Africa, we identify 10 high threat countries that are most at risk of deletions both spreading to and subsequently being rapidly selected for. If HRP2-based RDTs continue to be relied on for malaria case management, we predict that the major route for pfhrp2 deletions to spread is south out from the current hotspot in the Horn of Africa, moving through East Africa over the next 20 years. We explore the variation in modelled timelines through an extensive parameter sensitivity analysis and despite wide uncertainties, we identify three countries that have not yet switched RDTs (Senegal, Zambia and Kenya) that are robustly identified as high risk for pfhrp2/3 deletions. These results provide a refined and updated prediction model for the emergence of pfhrp2/3 deletions in an effort to help guide pfhrp2/3 policy and prioritise future surveillance efforts and innovation.
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Affiliation(s)
- Oliver J Watson
- Medical Research Council Centre for Global Infectious Disease Analysis, Faculty of Medicine, Imperial College London, London, UK
| | - Thu Nguyen-Anh Tran
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, 16802, USA
| | - Robert J Zupko
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, 16802, USA
| | - Tasmin Symons
- Malaria Atlas Project, Telethon Kids Institute, Perth Children's Hospital, Nedlands, WA 6009, Australia
| | | | | | - Susan Rumisha
- Malaria Atlas Project, Telethon Kids Institute, Perth Children's Hospital, Nedlands, WA 6009, Australia
| | - Paulina A Dzianach
- Malaria Atlas Project, Telethon Kids Institute, Perth Children's Hospital, Nedlands, WA 6009, Australia
| | - Nicholas Hathaway
- Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Isaac Kim
- Center for Computational Molecular Biology, Brown University, Providence, RI, USA
- Warren Alpert Medical School, Brown University, Providence, RI, USA
| | - Jonathan J Juliano
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, USA
- Division of Infectious Diseases, Department of Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jeffrey A Bailey
- Center for Computational Molecular Biology, Brown University, Providence, RI, USA
- Warren Alpert Medical School, Brown University, Providence, RI, USA
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI
| | | | - Lucy Okell
- Medical Research Council Centre for Global Infectious Disease Analysis, Faculty of Medicine, Imperial College London, London, UK
| | - Peter Gething
- Malaria Atlas Project, Telethon Kids Institute, Perth Children's Hospital, Nedlands, WA 6009, Australia
- Faculty of Health Sciences, Curtin University, Bentley, Australia
| | - Azra Ghani
- Medical Research Council Centre for Global Infectious Disease Analysis, Faculty of Medicine, Imperial College London, London, UK
| | - Maciej F Boni
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, 16802, USA
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Jonathan B Parr
- Division of Infectious Diseases, Department of Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jane Cunningham
- Global Malaria Programme, World Health Organization, Geneva, Switzerland
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Okanda D, Ndwiga L, Osoti V, Achieng N, Wambua J, Ngetsa C, Lubell-Doughtie P, Shankar A, Bejon P, Ochola-Oyier LI. Low frequency of Plasmodium falciparum hrp2/3 deletions from symptomatic infections at a primary healthcare facility in Kilifi, Kenya. FRONTIERS IN EPIDEMIOLOGY 2023; 3:1083114. [PMID: 38455911 PMCID: PMC10910971 DOI: 10.3389/fepid.2023.1083114] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 01/23/2023] [Indexed: 03/09/2024]
Abstract
There is a growing concern for malaria control in the Horn of Africa region due to the spread and rise in the frequency of Plasmodium falciparum Histidine-rich Protein (hrp) 2 and 3 deletions. Parasites containing these gene deletions escape detection by the major PfHRP2-based rapid diagnostic test. In this study, the presence of Pfhrp2/3 deletions was examined in uncomplicated malaria patients in Kilifi County, from a region of moderate-high malaria transmission. 345 samples were collected from the Pingilikani dispensary in 2019/2020 during routine malaria care for patients attending this primary health care facility. The Carestart™ RDT and microscopy were used to test for malaria. In addition, qPCR was used to confirm the presence of parasites. In total, 249 individuals tested positive for malaria by RDT, 242 by qPCR, and 170 by microscopy. 11 samples that were RDT-negative and microscopy positive and 25 samples that were qPCR-positive and RDT-negative were considered false negative tests and were examined further for Pfhrp2/3 deletions. Pfhrp2/3-negative PCR samples were further genotyped at the dihydrofolate reductase (Pfdhfr) gene which served to further confirm that parasite DNA was present in the samples. The 242 qPCR-positive samples (confirmed the presence of DNA) were also selected for Pfhrp2/3 genotyping. To determine the frequency of false negative results in low parasitemia samples, the RDT- and qPCR-negative samples were genotyped for Pfdhfr before testing for Pfhrp2/3. There were no Pfhrp2 and Pfhrp3 negative but positive for dhfr parasites in the 11 (RDT negative and microscopy positive) and 25 samples (qPCR-positive and RDT-negative). In the larger qPCR-positive sample set, only 5 samples (2.1%) were negative for both hrp2 and hrp3, but positive for dhfr. Of the 5 samples, there were 4 with more than 100 parasites/µl, suggesting true hrp2/3 deletions. These findings revealed that there is currently a low prevalence of Pfhrp2 and Pfhrp3 deletions in the health facility in Kilifi. However, routine monitoring in other primary health care facilities across the different malaria endemicities in Kenya is urgently required to ensure appropriate use of malaria RDTs.
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Affiliation(s)
- Dorcas Okanda
- Biosciences Department, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Leonard Ndwiga
- Biosciences Department, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Victor Osoti
- Biosciences Department, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Nicole Achieng
- Biosciences Department, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Juliana Wambua
- Biosciences Department, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Caroline Ngetsa
- Biosciences Department, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Anuraj Shankar
- Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, University of Oxford, Oxford, United Kingdom
| | - Philip Bejon
- Biosciences Department, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, University of Oxford, Oxford, United Kingdom
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Molina-de la Fuente I, Benito MJS, Flevaud L, Ousley J, Pasquale HA, Julla A, Abdi AM, Chol BT, Abubakr B, Benito A, Casademont C, Nanclares C, Berzosa P. Plasmodium falciparum pfhrp2 and pfhrp3 Gene Deletions in Malaria-Hyperendemic Region, South Sudan. Emerg Infect Dis 2023; 29:154-159. [PMID: 36573593 PMCID: PMC9796199 DOI: 10.3201/eid2901.220775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Pfhrp2 and pfhrp3 gene deletions threaten the use of Plasmodium falciparum malaria rapid diagnostic tests globally. In South Sudan, deletion frequencies were 15.6% for pfhrp2, 20.0% for pfhrp3, and 7.5% for double deletions. Deletions were approximately twice as prevalent in monoclonal infections than in polyclonal infections.
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Agaba BB, Rugera SP, Mpirirwe R, Atekat M, Okubal S, Masereka K, Erionu M, Adranya B, Nabirwa G, Odong PB, Mukiibi Y, Ssewanyana I, Nabadda S, Muwanguzi E. Asymptomatic malaria infection, associated factors and accuracy of diagnostic tests in a historically high transmission setting in Northern Uganda. Malar J 2022; 21:392. [PMID: 36550492 PMCID: PMC9783970 DOI: 10.1186/s12936-022-04421-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 12/17/2022] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Asymptomatic malaria infections are important parasite reservoirs and could sustain transmission in the population, but they are often unreported. A community-based survey was conducted to investigate the prevalence and factors associated with asymptomatic malaria infections in a historically high transmission setting in northern Uganda. METHODS Using a cross-sectional design, 288 children aged 2-15 years were enrolled and tested for the presence of malaria parasites using rapid diagnostic tests (RDTs) and blood smear microscopy between January to May 2022. Statistical analysis was performed using the exact binomial and Fisher's exact test with p ≤ 0.05 indicating significance. The logistic regression was used to explore factors associated with asymptomatic malaria infections. RESULTS Overall, the prevalence of asymptomatic infection was 34.7% (95% CI 29.2-40.5) with the highest observed in children 5-10 years 45.9% (95% CI 35.0-57.0). Gweri village accounted for 39.1% (95% CI 27.6-51.6) of malaria infections. Median parasite density was 1500 parasites/µl of blood. Plasmodium falciparum was the dominant species (86%) followed by Plasmodium malariae (5%). Factors associated with asymptomatic malaria infection were sleeping under mosquito net (Adjusted Odds Ratio (aOR) 0.27; 95% CI 0.13-0.56), p = 0.001 and presence of village health teams (VHTs) (aOR 0.02; 95% CI 0.01-0.45), p = 0.001. Sensitivity and specificity were higher for the P. falciparum/pLDH RDTs compared to HRP2-only RDTs, 90% (95% CI 86.5-93.5) and 95.2% (95% CI 92.8-97.7), p = 0.001, respectively. CONCLUSION Asymptomatic malaria infections were present in the study population and this varied with place and person in the different age groups. Plasmodium falciparum was the dominant parasite species however the presence of P. malariae and Plasmodium ovale was observed, which may have implication for the choice and deployment of diagnostic tools. Individuals who slept under mosquito net or had presence of functional VHTs were less likely to have asymptomatic malaria infection. P.f/pLDH RDTs performed better than the routinely used HRP2 RDTs. In view of these findings, investigation and reporting of asymptomatic malaria reservoirs through community surveys is recommended for accurate disease burden estimate and better targeting of control.
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Affiliation(s)
- Bosco B. Agaba
- grid.33440.300000 0001 0232 6272Department of Medical Laboratory Science, Mbarara University of Science and Technology, Mbarara, Uganda ,grid.415705.2National Malaria Control Division, Ministry of Health, Kampala, Uganda ,National Malaria Reference Laboratory, Central Public Health Laboratory Services, Kampala, Uganda ,grid.463352.50000 0004 8340 3103Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Simon P. Rugera
- grid.33440.300000 0001 0232 6272Department of Medical Laboratory Science, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Ruth Mpirirwe
- grid.11194.3c0000 0004 0620 0548Department of Statistics, Makerere University, Kampala, Uganda
| | - Martha Atekat
- grid.33440.300000 0001 0232 6272Department of Medical Laboratory Science, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Samuel Okubal
- grid.33440.300000 0001 0232 6272Department of Medical Laboratory Science, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Khalid Masereka
- grid.33440.300000 0001 0232 6272Department of Medical Laboratory Science, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Miseal Erionu
- grid.33440.300000 0001 0232 6272Department of Medical Laboratory Science, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Bosco Adranya
- grid.33440.300000 0001 0232 6272Department of Medical Laboratory Science, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Gertrude Nabirwa
- grid.33440.300000 0001 0232 6272Department of Medical Laboratory Science, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Patrick B. Odong
- grid.33440.300000 0001 0232 6272Department of Medical Laboratory Science, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Yasin Mukiibi
- Uganda Institute of Allied and Management Sciences, Kampala, Uganda
| | - Isaac Ssewanyana
- National Malaria Reference Laboratory, Central Public Health Laboratory Services, Kampala, Uganda ,grid.463352.50000 0004 8340 3103Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Susan Nabadda
- National Malaria Reference Laboratory, Central Public Health Laboratory Services, Kampala, Uganda
| | - Enoch Muwanguzi
- grid.33440.300000 0001 0232 6272Department of Medical Laboratory Science, Mbarara University of Science and Technology, Mbarara, Uganda ,Uganda Institute of Allied and Management Sciences, Kampala, Uganda
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9
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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:tropicalmed7100265. [PMID: 36288006 PMCID: PMC9611031 DOI: 10.3390/tropicalmed7100265] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [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
- Correspondence: or
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10
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Talisuna AO, D'Alessandro U. Interplay between sickle cell anaemia and Plasmodium falciparum malaria. THE LANCET. CHILD & ADOLESCENT HEALTH 2022; 6:594-595. [PMID: 35785795 DOI: 10.1016/s2352-4642(22)00169-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 05/27/2022] [Indexed: 06/15/2023]
Affiliation(s)
- Ambrose Otau Talisuna
- Emergency Preparedness and Response Cluster, World Health Organization, Regional Office for Africa, Brazzaville, Congo.
| | - Umberto D'Alessandro
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, London, UK
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11
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Uyoga S, Olupot-Olupot P, Connon R, Kiguli S, Opoka RO, Alaroker F, Muhindo R, Macharia AW, Dondorp AM, Gibb DM, Walker AS, George EC, Maitland K, Williams TN. Sickle cell anaemia and severe Plasmodium falciparum malaria: a secondary analysis of the Transfusion and Treatment of African Children Trial (TRACT). THE LANCET. CHILD & ADOLESCENT HEALTH 2022; 6:606-613. [PMID: 35785794 PMCID: PMC7613576 DOI: 10.1016/s2352-4642(22)00153-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 04/27/2022] [Accepted: 04/29/2022] [Indexed: 11/18/2022]
Abstract
BACKGROUND Sickle cell anaemia (SCA) has historically been associated with high levels of childhood mortality in Africa. Although malaria has a major contribution to this mortality, to date, the clinical pathology of malaria among children with SCA has been poorly described. We aimed to explore the relationship between SCA and Plasmodium falciparum malaria in further detail by investigating the burden and severity of malaria infections among children recruited with severe anaemia to the TRACT trial of blood transfusion in Africa. METHODS This study is a post-hoc secondary analysis of the TRACT trial data, conducted after trial completion. TRACT was an open-label, multicentre, factorial, randomised controlled trial enrolling children aged 2 months to 12 years who presented with severe anaemia (haemoglobin <6·0 g/dL) to four hospitals in Africa. This secondary analysis is restricted to Uganda, where the birth prevalence of SCA is approximately 1% and malaria transmission is high. Children were classified as normal (HbAA), heterozygous (HbAS), or homozygous (HbSS; SCA) for the rs334 A→T sickle mutation in HBB following batch-genotyping by PCR at the end of the trial. To avoid confounding from SCA-specific medical interventions, we considered children with an existing diagnosis of SCA (known SCA) separately from those diagnosed at the end of the trial (unknown SCA). The outcomes considered in this secondary analysis were measures of P falciparum parasite burden, features of severe malaria, and mortality at day 28 in malaria-positive children. FINDINGS Between Sept 17, 2014, and May 15, 2017, 3944 children with severe anaemia were enrolled into the TRACT trial. 3483 children from Uganda were considered in this secondary analysis. Overall, 1038 (30%) of 3483 Ugandan children had SCA. 1815 (78%) of 2321 children without SCA (HbAA) tested positive for P falciparum malaria, whereas the prevalence was significantly lower in children with SCA (347 [33%] of 1038; p<0·0001). Concentrations of plasma P falciparum histidine-rich protein 2 (PfHRP2), a marker of the total burden of malaria parasites within an individual, were significantly lower in children with either known SCA (median 8 ng/mL; IQR 0-57) or unknown SCA (7 ng/mL; 0-50) than in HbAA children (346 ng/mL; 21-2121; p<0·0001). In contrast to HbAA children, few HbSS children presented with classic features of severe and complicated malaria, but both the frequency and severity of anaemia were higher in HbSS children. We found no evidence for increased mortality at day 28 in those with SCA compared with those without SCA overall (hazard ratios 1·07 [95% CI 0·31-3·76] for known SCA and 0·67 [0·15-2·90] for unknown SCA). INTERPRETATION The current study suggests that children with SCA are innately protected against classic severe malaria. However, it also shows that even low-level infections can precipitate severe anaemic crises that would likely prove fatal without rapid access to blood transfusion services. FUNDING UK Medical Research Council, Wellcome, and UK National Institute for Health and Care Research.
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Affiliation(s)
- Sophie Uyoga
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Peter Olupot-Olupot
- Busitema University Faculty of Health Sciences, Mbale Regional Referral Hospital, Mbale, Uganda; Mbale Clinical Research Institute, Mbale, Uganda
| | - Roisin Connon
- Medical Research Council Clinical Trials Unit (MRC CTU) at University College London, London, UK
| | - Sarah Kiguli
- Department of Paediatrics and Child Health, School of Medicine, Makerere University, Kampala, Uganda
| | - Robert O Opoka
- Department of Paediatrics and Child Health, School of Medicine, Makerere University, Kampala, Uganda
| | | | - Rita Muhindo
- Mbale Clinical Research Institute, Mbale, Uganda
| | | | - Arjen M Dondorp
- Mahidol-Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Diana M Gibb
- Medical Research Council Clinical Trials Unit (MRC CTU) at University College London, London, UK
| | - A Sarah Walker
- Medical Research Council Clinical Trials Unit (MRC CTU) at University College London, London, UK
| | - Elizabeth C George
- Medical Research Council Clinical Trials Unit (MRC CTU) at University College London, London, UK
| | - Kathryn Maitland
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya; Department of Infectious Disease and Institute of Global Health Innovation, Division of Medicine, Imperial College London, London, UK
| | - Thomas N Williams
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya; Department of Infectious Disease and Institute of Global Health Innovation, Division of Medicine, Imperial College London, London, UK.
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12
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Beshir KB, Parr JB, Cunningham J, Cheng Q, Rogier E. Screening strategies and laboratory assays to support Plasmodium falciparum histidine-rich protein deletion surveillance: where we are and what is needed. Malar J 2022; 21:201. [PMID: 35751070 PMCID: PMC9233320 DOI: 10.1186/s12936-022-04226-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 06/17/2022] [Indexed: 11/10/2022] Open
Abstract
Rapid diagnostic tests (RDTs) detecting Plasmodium falciparum histidine-rich protein 2 (HRP2) have been an important tool for malaria diagnosis, especially in resource-limited settings lacking quality microscopy. Plasmodium falciparum parasites with deletion of the pfhrp2 gene encoding this antigen have now been identified in dozens of countries across Asia, Africa, and South America, with new reports revealing a high prevalence of deletions in some selected regions. To determine whether HRP2-based RDTs are appropriate for continued use in a locality, focused surveys and/or surveillance activities of the endemic P. falciparum population are needed. Various survey and laboratory methods have been used to determine parasite HRP2 phenotype and pfhrp2 genotype, and the data collected by these different methods need to be interpreted in the appropriate context of survey and assay utilized. Expression of the HRP2 antigen can be evaluated using point-of-care RDTs or laboratory-based immunoassays, but confirmation of a deletion (or mutation) of pfhrp2 requires more intensive laboratory molecular assays, and new tools and strategies for rigorous but practical data collection are particularly needed for large surveys. Because malaria diagnostic strategies are typically developed at the national level, nationally representative surveys and/or surveillance that encompass broad geographical areas and large populations may be required. Here is discussed contemporary assays for the phenotypic and genotypic evaluation of P. falciparum HRP2 status, consider their strengths and weaknesses, and highlight key concepts relevant to timely and resource-conscious workflows required for efficient diagnostic policy decision making.
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Affiliation(s)
- Khalid B Beshir
- Faculty of Infectious Diseases, London School of Hygiene and Tropical Diseases, Keppel Street, London, WC1E 7HT, UK
| | - Jonathan B Parr
- Division of Infectious Diseases and Institute for Global Health and Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Jane Cunningham
- Global Malaria Programme, World Health Organization, Geneva, Switzerland
| | - Qin Cheng
- Drug Resistance and Diagnostics, Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Australia.,QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Eric Rogier
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, 30029, USA.
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13
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Deletions of the Plasmodium falciparum histidine-rich protein 2/3 genes are common in field isolates from north-eastern Tanzania. Sci Rep 2022; 12:5802. [PMID: 35388127 PMCID: PMC8987040 DOI: 10.1038/s41598-022-09878-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 03/30/2022] [Indexed: 11/26/2022] Open
Abstract
Plasmodium falciparum parasites lacking histidine-rich protein 2 and 3 (pfhrp2/3) genes have been reported in several parts of the world. These deletions are known to compromise the effectiveness of HRP2-based malaria rapid diagnostic tests (HRP2-RDT). The National Malaria Control Programme (NMCP) in Tanzania adopted HRP2-RDTs as a routine tool for malaria diagnosis in 2009 replacing microscopy in many Health facilities. We investigated pfhrp2/3 deletions in 122 samples from two areas with diverse malaria transmission intensities in Northeastern Tanzania. Pfhrp2 deletion was confirmed in 1.6% of samples while pfhrp3 deletion was confirmed in 50% of samples. We did not find parasites with both pfhrp2 and pfhrp3 deletions among our samples. Results from this study highlight the need for systematic surveillance of pfhrp2/3 deletions in Tanzania to understand their prevalence and determine their impact on the performance of mRDT.
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14
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Plasmodium falciparum pfhrp2 and pfhrp3 gene deletions among patients in the DRC enrolled from 2017 to 2018. Sci Rep 2021; 11:22979. [PMID: 34837020 PMCID: PMC8626453 DOI: 10.1038/s41598-021-02452-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 11/15/2021] [Indexed: 11/08/2022] Open
Abstract
Rapid diagnostic tests (RDTs) detecting histidine-rich protein 2 (HRP2) and HRP3 are widely used throughout sub-Saharan Africa (SSA) to diagnose Plasmodium falciparum malaria. However, multiple SSA countries have reported pfhrp2 and pfhrp3 (pfhrp2/3) gene deletions. Blood samples (n = 1109) collected from patients with P. falciparum infection from six health facilities throughout the Democratic Republic of the Congo (DRC) from March 2017 to January 2018 were evaluated for pfhrp2/3 deletions. Samples were assayed for HRP2, pan-Plasmodium LDH (pLDH) and aldolase (pAldolase) antigens by bead-based multiplex antigen assay. Samples with low HRP2 concentration compared to pLDH and pAldolase antigens were selected for further pfhrp2/3 genotyping PCRs. The majority of blood samples (93.3%, 1035/1109) had high concentrations of the HRP2 antigen. Single deletions of pfhrp2 were identified in 0.27% (3/1109) of screened samples, with one sample from each of the Kapolowe, Mikalayi, and Rutshuru study sites. A pfhrp3 single deletion (0.09%, 1/1109) was found in the Kapolowe site. Dual pfhrp2 and pfhrp3 deletions were not observed. Due to, the low numbers of pfhrp2 deletions and the sporadic locations of these deletions, the use of HRP2-based RDTs appears to still be appropriate for these locations in DRC.
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15
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Singh B, McCaffery JN, Kong A, Ah Y, Wilson S, Chatterjee S, Tomar D, Aidoo M, Udhayakumar V, Rogier E. Purification of native histidine-rich protein 2 (nHRP2) from Plasmodium falciparum culture supernatant, infected RBCs, and parasite lysate. Malar J 2021; 20:405. [PMID: 34657602 PMCID: PMC8522059 DOI: 10.1186/s12936-021-03946-1] [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: 07/30/2021] [Accepted: 10/06/2021] [Indexed: 11/16/2022] Open
Abstract
Background Despite the widespread use of histidine-rich protein 2 (HRP2)-based rapid diagnostic tests (RDTs), purified native HRP2 antigen is not standardly used in research applications or assessment of RDTs used in the field. Methods This report describes the purification of native HRP2 (nHRP2) from the HB3 Plasmodium falciparum culture strain. As this culture strain lacks pfhrp3 from its genome, it is an excellent source of HRP2 protein only and does not produce the closely-related HRP3. The nHRP2 protein was isolated from culture supernatant, infected red blood cells (iRBCs), and whole parasite lysate using nickel-metal chelate chromatography. Biochemical characterization of nHRP2 from HB3 culture was conducted by SDS-PAGE and western blotting, and nHRP2 was assayed by RDT, ELISA, and bead-based immunoassay. Results Purified nHRP2 was identified by SDS-PAGE and western blot as a − 60 kDa protein that bound anti-HRP-2 monoclonal antibodies. Mouse anti-HRP2 monoclonal antibody was found to produce high optical density readings between dilutions of 1:100 and 1:3,200 by ELISA with assay signal observed up to a 1:200,000 dilution. nHRP2 yield from HB3 culture by bead-based immunoassay revealed that both culture supernatant and iRBC lysate were practical sources of large quantities of this antigen, producing a total yield of 292.4 µg of nHRP2 from two pooled culture preparations. Assessment of nHRP2 recognition by RDTs revealed that Carestart Pf HRP2 and HRP2/pLDH RDTs detected purified nHRP2 when applied at concentrations between 20.6 and 2060 ng/mL, performing within a log-fold dilution of commercially-available recombinant HRP2. The band intensity observed for the nHRP2 dilutions was equivalent to that observed for P. falciparum culture strain dilutions of 3D7 and US06 F Nigeria XII between 12.5 and 1000 parasites/µL. Conclusions Purified nHRP2 could be a valuable reagent for laboratory applications as well as assessment of new and existing RDTs prior to their use in clinical settings. These results establish that it is possible to extract microgram quantities of the native HRP2 antigen from HB3 culture and that this purified protein is well recognized by existing monoclonal antibody lines and RDTs. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03946-1.
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Affiliation(s)
- Balwan Singh
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, 30329, USA
| | - Jessica N McCaffery
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, 30329, USA
| | - Amy Kong
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, 30329, USA
| | - Yong Ah
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, 30329, USA
| | - Scott Wilson
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, 30329, USA
| | | | - Deepak Tomar
- Department of Medicine, Division of Rheumatology, Emory University, Atlanta, GA, USA.,Lowance Center for Human Immunology, Emory University, Atlanta, GA, USA
| | - Michael Aidoo
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, 30329, USA
| | - Venkatachalam Udhayakumar
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, 30329, USA
| | - Eric Rogier
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, 30329, USA.
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16
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Agaba BB, Anderson K, Gresty K, Prosser C, Smith D, Nankabirwa JI, Nsobya S, Yeka A, Namubiru R, Arinaitwe E, Mbaka P, Kissa J, Lim CS, Karamagi C, Nakayaga JK, Kamya MR, Cheng Q. Genetic diversity and genetic relatedness in Plasmodium falciparum parasite population in individuals with uncomplicated malaria based on microsatellite typing in Eastern and Western regions of Uganda, 2019-2020. Malar J 2021; 20:242. [PMID: 34059047 PMCID: PMC8165787 DOI: 10.1186/s12936-021-03763-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 05/11/2021] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Genetic diversity and parasite relatedness are essential parameters for assessing impact of interventions and understanding transmission dynamics of malaria parasites, however data on its status in Plasmodium falciparum populations in Uganda is limited. Microsatellite markers and DNA sequencing were used to determine diversity and molecular characterization of P. falciparum parasite populations in Uganda. METHODS A total of 147 P. falciparum genomic DNA samples collected from cross-sectional surveys in symptomatic individuals of 2-10 years were characterized by genotyping of seven highly polymorphic neutral microsatellite markers (n = 85) and genetic sequencing of the Histidine Rich Protein 2 (pfhrp2) gene (n = 62). ArcGIS was used to map the geographical distribution of isolates while statistical testing was done using Student's t-test or Wilcoxon's rank-sum test and Fisher's exact test as appropriate at P ≤ 0.05. RESULTS Overall, 75.5% (95% CI 61.1-85.8) and 24.5% (95% CI14.2-38.9) of parasites examined were of multiclonal (mixed genotype) and single clone infections, respectively. Multiclonal infections occurred more frequently in the Eastern region 73.7% (95% CI 48.8-89.1), P < 0.05. Overall, multiplicity of infection (MOI) was 1.9 (95% CI 1.7-2.1), P = 0.01 that was similar between age groups (1.8 vs 1.9), P = 0.60 and regions (1.9 vs 1.8), P = 0.43 for the < 5 and ≥ 5 years and Eastern and Western regions, respectively. Genomic sequencing of the pfhrp2 exon2 revealed a high level of genetic diversity reflected in 96.8% (60/62) unique sequence types. Repeat type AHHAAAHHATD and HRP2 sequence Type C were more frequent in RDT-/PCR + samples (1.9% vs 1.5%) and (13% vs 8%), P < 0.05 respectively. Genetic relatedness analysis revealed small clusters of gene deleted parasites in Uganda, but no clustering with Eritrean parasites. CONCLUSION High level of genetic diversity of P. falciparum parasites reflected in the frequency of multiclonal infections, multiplicity of infection and variability of the pfhrp2 gene observed in this study is consistent with the high malaria transmission intensity in these settings. Parasite genetic analysis suggested spontaneous emergence and clonal expansion of pfhrp2 deleted parasites that require close monitoring to inform national malaria diagnosis and case management policies.
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Affiliation(s)
- Bosco B Agaba
- College of Health Sciences, Makerere University, Kampala, Uganda. .,National Malaria Control Division, Kampala, Uganda.
| | - Karen Anderson
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia.,Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Australia
| | - Karryn Gresty
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia.,Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Australia
| | - Christiane Prosser
- Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Australia
| | - David Smith
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia.,Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Australia
| | - Joaniter I Nankabirwa
- College of Health Sciences, Makerere University, Kampala, Uganda.,Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Sam Nsobya
- College of Health Sciences, Makerere University, Kampala, Uganda.,Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Adoke Yeka
- College of Health Sciences, Makerere University, Kampala, Uganda.,Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Rhoda Namubiru
- College of Health Sciences, Makerere University, Kampala, Uganda
| | | | - Paul Mbaka
- World Health Organization Country Office, Kampala, Uganda
| | - John Kissa
- National Health Information Division, Ministry of Health, Kampala, Uganda
| | - Chae Seung Lim
- Department of Laboratory Medicine, College of Health Sciences, Korea University, Seoul, South Korea
| | - Charles Karamagi
- College of Health Sciences, Makerere University, Kampala, Uganda
| | - Joan K Nakayaga
- College of Health Sciences, Makerere University, Kampala, Uganda
| | - Moses R Kamya
- College of Health Sciences, Makerere University, Kampala, Uganda.,Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Qin Cheng
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia.,Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Australia
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17
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Kong A, Wilson SA, Ah Y, Nace D, Rogier E, Aidoo M. HRP2 and HRP3 cross-reactivity and implications for HRP2-based RDT use in regions with Plasmodium falciparum hrp2 gene deletions. Malar J 2021; 20:207. [PMID: 33926477 PMCID: PMC8086288 DOI: 10.1186/s12936-021-03739-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 04/19/2021] [Indexed: 01/29/2023] Open
Abstract
Background The Plasmodium falciparum antigen histidine rich protein 2 (HRP2) is a preferred target for malaria rapid diagnostic tests (RDTs) because of its abundant production by the parasite and thermal stability. As a result, a majority of RDTs procured globally target this antigen. However, previous reports from South America and recent reports from sub-Saharan Africa and Asia indicate that certain P. falciparum parasites have deletions of the gene coding for HRP2. The HRP2 antigen is paralogous to another P. falciparum antigen HRP3 and some antibodies to HRP2 cross-react with HRP3. Multiple parasites have been described with deletions of one or both hrp2 and hrp3 genes. It is unclear how the various combinations of hrp2 and hrp3 deletion genotypes affect clinical sensitivity of HRP2-based RDTs. Methods Cross-reactivity between HRP2 and HRP3 was tested on malaria RDTs using culture-adapted P. falciparum parasites with both hrp2 and hrp3 intact or with one or both genes deleted. Ten-fold serial dilutions of four culture-adapted P. falciparum parasites [3D7 (hrp2+/hrp3+), Dd2 (hrp2−/hrp3+), HB3 (hrp2+/hrp3−) and 3BD5 (hrp2−/hrp3−)] ranging from 100,000 to 0.01 parasites/µL were prepared. HRP2, Plasmodium lactate dehydrogenase (pLDH) and aldolase concentrations were determined for the diluted samples using a multiplex bead assay. The samples were subsequently tested on three RDT products designed to detect P. falciparum by HRP2 alone or in combination with pLDH. Results At parasite densities of approximately 1000 parasites/µL, parasites that expressed either hrp2 or hrp3 were detected by all three RDTs. Multiplex based antigen measurement using HRP2- conjugated beads demonstrated higher antigen concentration when both hrp2 and hrp3 genes were intact (3D7 parasites, 47.9 ng/ml) compared to HB3 (3.02 ng/mL) and Dd2 (0.20 ng/mL) strains that had one gene deleted. 3D7 at 10 parasites/µL (0.45 ng/mL) was reactive on all three RDT products whereas none of the other parasites were reactive at that density. Conclusions Above a certain antigen threshold, HRP3 cross-reactivity on HRP2-based RDTs is sufficient to mask the effects of deletions of hrp2 only. Studies of hrp2 deletion and its effects on HRP2-based RDTs must be studied alongside hrp3 deletions and include clinical sample reactivity on HRP2-based tests.
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Affiliation(s)
- Amy Kong
- Malaria Branch, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA, 30329, USA
| | - Scott A Wilson
- Malaria Branch, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA, 30329, USA.,The CDC Foundation, 600 Peachtree Street NE, Suite 1000, Atlanta, GA, 30308, USA
| | - Yong Ah
- Malaria Branch, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA, 30329, USA.,The CDC Foundation, 600 Peachtree Street NE, Suite 1000, Atlanta, GA, 30308, USA
| | - Douglas Nace
- Malaria Branch, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA, 30329, USA
| | - Eric Rogier
- Malaria Branch, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA, 30329, USA
| | - Michael Aidoo
- Malaria Branch, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA, 30329, USA.
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18
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Mu J, Yu LL, Wellems TE. Sensitive Immunoassay Detection of Plasmodium Lactate Dehydrogenase by Inductively Coupled Plasma Mass Spectrometry. Front Cell Infect Microbiol 2021; 10:620419. [PMID: 33505925 PMCID: PMC7831609 DOI: 10.3389/fcimb.2020.620419] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 11/24/2020] [Indexed: 12/28/2022] Open
Abstract
Rapid, reliable, and sensitive detection of Plasmodium infection is central to malaria control and elimination. Many Malaria Rapid Diagnostic Tests (RDTs) developed for this purpose depend upon immunoassays that can be improved by advances in bound antibody sensor technology. In a previous study, immuno-polymerase chain reaction (PCR) was shown to provide highly sensitive detection of Plasmodium falciparum lactate dehydrogenase (PfLDH) in monoclonal antibody (mAb) sandwich assays. Here, we show comparably high immunoassay sensitivity by inductively coupled plasma mass spectrometry (ICP-MS) detection of gold nanoparticles (AuNPs). Following capture of PfLDH with the primary mAb and binding of the AuNP-labeled detection mAb, ICP-MS signals from the AuNPs provided quantitative measures of recombinant PfLDH test dilutions and P. falciparum-infected erythrocytes. A detection limit of 1.5 pg/mL was achieved with the PfLDH protein. Parasitemia in cultures of P. falciparum-infected erythrocytes could be detected to a lower limit of 1.6 parasite/μl (p/μl) for early ring-stage forms and 0.3 p/μl for mixed stages including mature trophozoites and schizont-stages. These results show that ICP-MS detection of AuNPs can support highly sensitive and accurate detection of Plasmodium infection.
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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, Rockville, MD, United States
| | - Lee L. Yu
- Chemical Sciences Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, United States
| | - Thomas E. Wellems
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, United States
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19
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Nsobya SL, Walakira A, Namirembe E, Kiggundu M, Nankabirwa JI, Ruhamyankaka E, Arinaitwe E, Conrad MD, Kamya MR, Dorsey G, Rosenthal PJ. Deletions of pfhrp2 and pfhrp3 genes were uncommon in rapid diagnostic test-negative Plasmodium falciparum isolates from Uganda. Malar J 2021; 20:4. [PMID: 33386076 PMCID: PMC7777526 DOI: 10.1186/s12936-020-03547-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 12/12/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Rapid diagnostic tests (RDTs) play a key role in malaria case management. The most widely used RDT identifies Plasmodium falciparum based on immunochromatographic recognition of P. falciparum histidine-rich protein 2 (PfHRP2). Deletion of the paralogous pfhrp2 and pfhrp3 genes leads to false-negative PfHRP2-based RDTs, and has been reported in P. falciparum infections from South America and Africa. However, identification of pfhrp2/pfhrp3 deletions has usually been based only on failure to amplify these genes using PCR, without confirmation based on PfHRP2 protein expression, and understanding of the true prevalence of deletions is incomplete. METHODS Deletions of pfhrp2/pfhrp3 in blood samples were investigated from cross-sectional surveys in 2012-13 in three regions of varied malaria transmission intensity in Uganda. Samples with positive Giemsa-stained thick blood smears, but negative PfHRP2-based RDTs were evaluated by PCR amplification of conserved subunit ribosomal DNA for Plasmodium species, PCR amplification of pfhrp2 and pfhrp3 genes to identify deletions, and bead-based immunoassays for expression of PfHRP2. RESULTS Of 3516 samples collected in cross-sectional surveys, 1493 (42.5%) had positive blood smears, of which 96 (6.4%) were RDT-negative. Of these 96 RDT-negative samples, P. falciparum DNA was identified by PCR in 56 (58%) and only non-falciparum plasmodial DNA in 40 (42%). In all 56 P. falciparum-positive samples there was a failure to amplify pfhrp2 or pfhrp3: in 25 (45%) pfhrp2 was not amplified, in 39 (70%) pfhrp3 was not amplified, and in 19 (34%) neither gene was amplified. For the 39 P. falciparum-positive, RDT-negative samples available for analysis of protein expression, PfHRP2 was not identified by immunoassay in only four samples (10.3%); these four samples all had failure to amplify both pfhrp2 and pfhrp3 by PCR. Thus, only four of 96 (4.2%) smear-positive, RDT-negative samples had P. falciparum infections with deletion of pfhrp2 and pfhrp3 confirmed by failure to amplify the genes by PCR and lack of expression of PfHRP2 demonstrated by immunoassay. CONCLUSION False negative RDTs were uncommon. Deletions in pfhrp2 and pfhrp3 explained some of these false negatives, but most false negatives were not due to deletion of the pfhrp2 and pfhrp3 genes.
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Affiliation(s)
- Sam L Nsobya
- Infectious Diseases Research Collaboration, Kampala, Uganda. .,Department of Pathology, College of Health Science, Makerere University Kampala, Kampala, Uganda.
| | | | | | - Moses Kiggundu
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Joaniter I Nankabirwa
- Infectious Diseases Research Collaboration, Kampala, Uganda.,Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | | | | | - Melissa D Conrad
- Department of Medicine, University of California, San Francisco, CA, USA
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda.,Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Grant Dorsey
- Department of Medicine, University of California, San Francisco, CA, USA
| | - Philip J Rosenthal
- Department of Medicine, University of California, San Francisco, CA, USA
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20
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Bosco AB, Nankabirwa JI, Yeka A, Nsobya S, Gresty K, Anderson K, Mbaka P, Prosser C, Smith D, Opigo J, Namubiru R, Arinaitwe E, Kissa J, Gonahasa S, Won S, Lee B, Lim CS, Karamagi C, Cheng Q, Nakayaga JK, Kamya MR. Limitations of rapid diagnostic tests in malaria surveys in areas with varied transmission intensity in Uganda 2017-2019: Implications for selection and use of HRP2 RDTs. PLoS One 2020; 15:e0244457. [PMID: 33382787 PMCID: PMC7774953 DOI: 10.1371/journal.pone.0244457] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/09/2020] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Plasmodium falciparum histidine-rich protein 2 (HRP2)-based rapid diagnostic tests (RDTs) are exclusively recommended for malaria diagnosis in Uganda; however, their functionality can be affected by parasite-related factors that have not been investigated in field settings. METHODS Using a cross-sectional design, we analysed 219 RDT-/microscopy+ and 140 RDT+/microscopy+ dried blood spots obtained from symptomatic children aged 2-10 years from 48 districts in Uganda between 2017 and 2019. We aimed to investigate parasite-related factors contributing to false RDT results by molecular characterization of parasite isolates. ArcGIS software was used to map the geographical distribution of parasites. Statistical analysis was performed using chi-square or Fisher's exact tests, with P ≤ 0.05 indicating significance. Odds ratios (ORs) were used to assess associations, while logistic regression was performed to explore possible factors associated with false RDT results. RESULTS The presence of parasite DNA was confirmed in 92.5% (332/359) of the blood samples. The levels of agreement between the HRP2 RDT and PCR assay results in the (RDT+/microscopy+) and (RDT-/microscopy+) sample subsets were 97.8% (137/140) and 10.9% (24/219), respectively. Factors associated with false-negative RDT results in the (RDT-/microscopy+) samples were parasite density (<1,000/μl), pfhrp2/3 gene deletion and non-P. falciparum species (aOR 2.65, 95% CI: 1.62-4.38, P = 0.001; aOR 4.4, 95% CI 1.72-13.66, P = 0.004; and aOR 18.65, 95% CI: 5.3-38.7, P = 0.001, respectively). Overall, gene deletion and non-P. falciparum species contributed to 12.3% (24/195) and 19.0% (37/195) of false-negative RDT results, respectively. Of the false-negative RDTs results, 80.0% (156/195) were from subjects with low-density infections (< 25 parasites per 200 WBCs or <1,000/μl). CONCLUSION This is the first evaluation and report of the contributions of pfhrp2/3 gene deletion, non-P. falciparum species, and low-density infections to false-negative RDT results under field conditions in Uganda. In view of these findings, the use of HRP2 RDTs should be reconsidered; possibly, switching to combination RDTs that target alternative antigens, particularly in affected areas, may be beneficial. Future evaluations should consider larger and more representative surveys covering other regions of Uganda.
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Affiliation(s)
- Agaba B. Bosco
- College of Health Sciences, Makerere University, Kampala, Uganda
- National Malaria Control Division, Kampala, Uganda
| | - Joaniter I. Nankabirwa
- College of Health Sciences, Makerere University, Kampala, Uganda
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Adoke Yeka
- College of Health Sciences, Makerere University, Kampala, Uganda
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Sam Nsobya
- College of Health Sciences, Makerere University, Kampala, Uganda
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Karryn Gresty
- Australian Defence Force Malaria and Infectious Disease Institute, Queensland, Australia
- The Army Malaria Institute Laboratory, QIMR Berghofer Medical Research Institute, Kampala, Uganda
| | - Karen Anderson
- Australian Defence Force Malaria and Infectious Disease Institute, Queensland, Australia
- The Army Malaria Institute Laboratory, QIMR Berghofer Medical Research Institute, Kampala, Uganda
| | - Paul Mbaka
- World Health Organization Country Office, Kampala, Uganda
| | - Christiane Prosser
- Australian Defence Force Malaria and Infectious Disease Institute, Queensland, Australia
| | - David Smith
- Australian Defence Force Malaria and Infectious Disease Institute, Queensland, Australia
- The Army Malaria Institute Laboratory, QIMR Berghofer Medical Research Institute, Kampala, Uganda
| | - Jimmy Opigo
- National Malaria Control Division, Kampala, Uganda
| | - Rhoda Namubiru
- College of Health Sciences, Makerere University, Kampala, Uganda
| | | | - John Kissa
- National Health Information Division, Ministry of Health, Kampala, Uganda
| | | | - Sungho Won
- Department of Public Health Sciences, Seoul National University, Seoul, S. Korea
| | - Bora Lee
- Department of Public Health Sciences, Seoul National University, Seoul, S. Korea
| | - Chae Seung Lim
- Department of Laboratory Medicine, College of Health Sciences, Korea University, Seoul, S. Korea
| | - Charles Karamagi
- College of Health Sciences, Makerere University, Kampala, Uganda
| | - Qin Cheng
- Australian Defence Force Malaria and Infectious Disease Institute, Queensland, Australia
- The Army Malaria Institute Laboratory, QIMR Berghofer Medical Research Institute, Kampala, Uganda
| | - Joan K. Nakayaga
- College of Health Sciences, Makerere University, Kampala, Uganda
| | - Moses R. Kamya
- College of Health Sciences, Makerere University, Kampala, Uganda
- Infectious Diseases Research Collaboration, Kampala, Uganda
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