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Choi S, Choi H, Park SY, Kwak YG, Song JE, Shin SY, Baek JH, Shin HI, Cho SH, Lee SE, Kwon JR, Park S, Kim M, Oh HS, Kim YC, Kim MJ, Yeom JS. Association between CYP2D6 phenotype and recurrence of Plasmodium vivax infection in south Korean patients. Malar J 2022; 21:289. [PMID: 36217154 PMCID: PMC9552356 DOI: 10.1186/s12936-022-04311-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 09/30/2022] [Indexed: 11/25/2022] Open
Abstract
Background Primaquine is activated by CYP2D6 in the hepatocytes. In Korea, primaquine is the only hypnozoitocidal agent used for patients with vivax malaria. Thus, patients with poor CYP2D6 activity could have an increased risk of primaquine failure and subsequent relapse. The study sought to identify the association between CYP2D6 phenotype and recurrence of malaria in Korean patients. Methods A total of 102 patients with vivax malaria were prospectively enrolled from eight institutions in Korea. An additional 38 blood samples from patients with recurred vivax malaria were provided by the Korea Disease Control and Prevention Agency. Malaria recurrence was defined as more than one episode of vivax malaria in the same or consecutive years. CYP2D6 star alleles, phenotypes, and activity scores were examined. Results Genotyping for CYP2D6 was successful in 101 of the prospectively enrolled patients and 38 samples from the Korea Disease Control and Prevention Agency, of which 91 were included in the no-recurrence group and 48 were included in the recurrence group. Reduced CYP2D6 activity (intermediate metabolizer) phenotype was more common in the recurrence group than in the no-recurrence group (OR, 2.33 (95% CI, 1.14–4.77); p = 0.02). Patients with lower CYP2D6 activity had a higher probability of recurrence (p = 0.029). Conclusion This study suggests that CYP2D6 polymorphism may affect primaquine efficacy and thus Plasmodium vivax recurrence in Korea. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04311-6.
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Affiliation(s)
- Sungim Choi
- Division of Infectious Diseases, Department of Internal Medicine, Dongguk University Ilsan Hospital, Goyang-si, Gyeonggi-do, Republic of Korea
| | - Heun Choi
- Department of Infectious Diseases, National Health Insurance Service Ilsan Hospital, Goyang-si, Gyeonggi-do, Republic of Korea
| | - Seong Yeon Park
- Division of Infectious Diseases, Department of Internal Medicine, Dongguk University Ilsan Hospital, Goyang-si, Gyeonggi-do, Republic of Korea
| | - Yee Gyung Kwak
- Division of Infectious Diseases, Department of Internal Medicine, Inje University Ilsan Paik Hospital, Goyang-si, Gyeonggi-do, Republic of Korea
| | - Je Eun Song
- Division of Infectious Diseases, Department of Internal Medicine, Inje University Ilsan Paik Hospital, Goyang-si, Gyeonggi-do, Republic of Korea
| | - So Youn Shin
- Department of Internal Medicine, International St. Mary's Hospital, Catholic Kwandong University College of Medicine, Incheon, Republic of Korea
| | - Ji Hyeon Baek
- Department of Internal Medicine, Inha University College of Medicine, Incheon, Republic of Korea
| | - Hyun-Il Shin
- Division of Vectors and Parasitic Diseases, Bureau of Infectious Disease Diagnosis Control, Korea Disease Control and Prevention Agency, Chungcheongbuk-do, Republic of Korea
| | - Shin-Hyung Cho
- Division of Vectors and Parasitic Diseases, Bureau of Infectious Disease Diagnosis Control, Korea Disease Control and Prevention Agency, Chungcheongbuk-do, Republic of Korea
| | - Sang-Eun Lee
- Division of Vectors and Parasitic Diseases, Bureau of Infectious Disease Diagnosis Control, Korea Disease Control and Prevention Agency, Chungcheongbuk-do, Republic of Korea
| | - Jeong-Ran Kwon
- Division of Zoonotic and Vector borne Disease Control, Bureau of Infectious Disease Policy, Korea Disease Control and Prevention Agency, Chungcheongbuk-do, Republic of Korea
| | - Sookkyung Park
- Division of Zoonotic and Vector borne Disease Control, Bureau of Infectious Disease Policy, Korea Disease Control and Prevention Agency, Chungcheongbuk-do, Republic of Korea
| | - Miyoung Kim
- Division of Zoonotic and Vector borne Disease Control, Bureau of Infectious Disease Policy, Korea Disease Control and Prevention Agency, Chungcheongbuk-do, Republic of Korea
| | - Hong Sang Oh
- Department of Internal Medicine, Armed Forces Capital Hospital, Seongnam-si, Gyeonggi-do, Republic of Korea
| | - Yong Chan Kim
- Division of Infectious Diseases, Department of Internal Medicine, Yongin Severance Hospital, Yonsei University College of Medicine, Yongin-si, Republic of Korea
| | - Min Jae Kim
- Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
| | - Joon-Sup Yeom
- Division of Infectious Diseases, Department of Internal Medicine, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea.
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2
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de Pina-Costa A, Silvino ACR, Dos Santos EM, Pedro RS, Moreira J, Umana GL, da Silva ADT, da Rosa Santos OHL, de Deus Henriques KM, Daniel-Ribeiro CT, Brasil P, Sousa TN, Siqueira AM. Increased primaquine total dose prevents Plasmodium vivax relapses in patients with impaired CYP2D6 activity: report of three cases. Malar J 2021; 20:341. [PMID: 34391426 PMCID: PMC8364036 DOI: 10.1186/s12936-021-03869-x] [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: 02/11/2021] [Accepted: 07/28/2021] [Indexed: 11/25/2022] Open
Abstract
Background The relapsing nature of Plasmodium vivax infection is a major barrier to its control and elimination. Factors such as adequate dosing, adherence, drug quality, and pharmacogenetics can impact the effectiveness of radical cure of P. vivax and need to be adequately evaluated. CYP2D6 pathway mediates the activation of primaquine (primaquine) into an active metabolite(s) in hepatocytes, and impaired activity has been linked to a higher risk of relapse. Cases presentation Three patients diagnosed with P. vivax malaria presented repeated relapses after being initially treated with chloroquine (25 mg/kg) and primaquine (3.5 mg/kg in 14 days) at a non-endemic travel clinic. Recurring episodes were subsequently treated with a higher dose of primaquine (7 mg/kg in 14 days), which prevented further relapses in two patients. However, one patient still presented two episodes after a higher primaquine dose and was prescribed 300 mg of chloroquine weekly to prevent further episodes. Impaired CYP2D6 function was observed in all of them. Conclusion Lack of response to primaquine was associated with impaired CYP2D6 activity in three patients presenting multiple relapses followed in a non-endemic setting. Higher primaquine dosage was safe and effectively prevented relapses in two patients and should be further investigated as an option in Latin America. It is crucial to investigate the factors associated with unsuccessful radical cures and alternative therapeutic options.
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Affiliation(s)
- Anielle de Pina-Costa
- Laboratório de Pesquisa Clínica em Doenças Febris Agudas-Instituto Nacional de Infectologia (INI) Evandro Chagas, Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, RJ, Brazil.,Centro de Pesquisa Diagnóstico e Treinamento em Malária-Fiocruz, Rio de Janeiro, Brazil.,Centro Universitário Serra Dos Órgãos (UNIFESO), Teresópolis, RJ, Brazil
| | | | - Edwiges Motta Dos Santos
- Laboratório de Pesquisa Clínica em Doenças Febris Agudas-Instituto Nacional de Infectologia (INI) Evandro Chagas, Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, RJ, Brazil
| | - Renata Saraiva Pedro
- Laboratório de Pesquisa Clínica em Doenças Febris Agudas-Instituto Nacional de Infectologia (INI) Evandro Chagas, Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, RJ, Brazil.,Assessoria Clínica-Instituto em Tecnologia em Imunobiológicos-Fiocruz, Rio de Janeiro, Brazil
| | - José Moreira
- Laboratório de Pesquisa Clínica em Doenças Febris Agudas-Instituto Nacional de Infectologia (INI) Evandro Chagas, Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, RJ, Brazil.,Programa de Pós-Graduação Em Pesquisa Clínica, INI Evandro Chagas, Fiocruz, Rio de Janeiro, Brazil
| | - Gabriela Liseth Umana
- Laboratório de Pesquisa Clínica em Doenças Febris Agudas-Instituto Nacional de Infectologia (INI) Evandro Chagas, Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, RJ, Brazil
| | - Ana Danielle Tavares da Silva
- Laboratório de Pesquisa Clínica em Doenças Febris Agudas-Instituto Nacional de Infectologia (INI) Evandro Chagas, Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, RJ, Brazil
| | - Otília Helena Lupi da Rosa Santos
- Laboratório de Pesquisa Clínica em Doenças Febris Agudas-Instituto Nacional de Infectologia (INI) Evandro Chagas, Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, RJ, Brazil.,Centro de Pesquisa Diagnóstico e Treinamento em Malária-Fiocruz, Rio de Janeiro, Brazil
| | - Karina Medeiros de Deus Henriques
- Laboratório de Pesquisa Clínica em Doenças Febris Agudas-Instituto Nacional de Infectologia (INI) Evandro Chagas, Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, RJ, Brazil.,Programa de Pós-Graduação Em Pesquisa Clínica, INI Evandro Chagas, Fiocruz, Rio de Janeiro, Brazil
| | - Cláudio Tadeu Daniel-Ribeiro
- Centro de Pesquisa Diagnóstico e Treinamento em Malária-Fiocruz, Rio de Janeiro, Brazil.,Laboratório de Pesquisa Em Malária, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, RJ, Brazil
| | - Patrícia Brasil
- Laboratório de Pesquisa Clínica em Doenças Febris Agudas-Instituto Nacional de Infectologia (INI) Evandro Chagas, Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, RJ, Brazil.,Centro de Pesquisa Diagnóstico e Treinamento em Malária-Fiocruz, Rio de Janeiro, Brazil.,Programa de Pós-Graduação Em Pesquisa Clínica, INI Evandro Chagas, Fiocruz, Rio de Janeiro, Brazil
| | | | - André M Siqueira
- Laboratório de Pesquisa Clínica em Doenças Febris Agudas-Instituto Nacional de Infectologia (INI) Evandro Chagas, Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, RJ, Brazil. .,Centro de Pesquisa Diagnóstico e Treinamento em Malária-Fiocruz, Rio de Janeiro, Brazil. .,Programa de Pós-Graduação Em Pesquisa Clínica, INI Evandro Chagas, Fiocruz, Rio de Janeiro, Brazil.
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3
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Novel Insights into Plasmodium vivax Therapeutic Failure: CYP2D6 Activity and Time of Exposure to Malaria Modulate the Risk of Recurrence. Antimicrob Agents Chemother 2020; 64:AAC.02056-19. [PMID: 32122891 DOI: 10.1128/aac.02056-19] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 02/24/2020] [Indexed: 12/21/2022] Open
Abstract
Plasmodium vivax relapse is one of the major causes of sustained global malaria transmission. Primaquine (PQ) is the only commercial drug available to prevent relapses, and its efficacy is dependent on metabolic activation by cytochrome P450 2D6 (CYP2D6). Impaired CYP2D6 function, caused by allelic polymorphisms, leads to the therapeutic failure of PQ as a radical cure for P. vivax malaria. Here, we hypothesized that the host immune response to malaria parasites modulates susceptibility to P. vivax recurrences in association with CYP2D6 activity. We performed a 10-year retrospective study by genotyping CYP2D6 polymorphisms in 261 malaria-exposed individuals from the Brazilian Amazon. The immune responses against a panel of P. vivax blood-stage antigens were evaluated by serological assays. We confirmed our previous findings, which indicated an association between impaired CYP2D6 activity and a higher risk of multiple episodes of P. vivax recurrence (risk ratio, 1.75; 95% confidence interval [CI], 1.2 to 2.6; P = 0.0035). An important finding was a reduction of 3% in the risk of recurrence (risk ratio, 0.97; 95% CI, 0.96 to 0.98; P < 0.0001) per year of malaria exposure, which was observed for individuals with both reduced and normal CYP2D6 activity. Accordingly, subjects with long-term malaria exposure and persistent antibody responses to various antigens showed fewer episodes of malaria recurrence. Our findings have direct implications for malaria control, since it was shown that nonimmune individuals who do not respond adequately to treatment due to reduced CYP2D6 activity may present a significant challenge for sustainable progress toward P. vivax malaria elimination.
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4
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Taylor AR, Watson JA, Chu CS, Puaprasert K, Duanguppama J, Day NPJ, Nosten F, Neafsey DE, Buckee CO, Imwong M, White NJ. Resolving the cause of recurrent Plasmodium vivax malaria probabilistically. Nat Commun 2019; 10:5595. [PMID: 31811128 PMCID: PMC6898227 DOI: 10.1038/s41467-019-13412-x] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 10/29/2019] [Indexed: 11/23/2022] Open
Abstract
Relapses arising from dormant liver-stage Plasmodium vivax parasites (hypnozoites) are a major cause of vivax malaria. However, in endemic areas, a recurrent blood-stage infection following treatment can be hypnozoite-derived (relapse), a blood-stage treatment failure (recrudescence), or a newly acquired infection (reinfection). Each of these requires a different prevention strategy, but it was not previously possible to distinguish between them reliably. We show that individual vivax malaria recurrences can be characterised probabilistically by combined modelling of time-to-event and genetic data within a framework incorporating identity-by-descent. Analysis of pooled patient data on 1441 recurrent P. vivax infections in 1299 patients on the Thailand-Myanmar border observed over 1000 patient follow-up years shows that, without primaquine radical curative treatment, 3 in 4 patients relapse. In contrast, after supervised high-dose primaquine only 1 in 40 relapse. In this region of frequent relapsing P. vivax, failure rates after supervised high-dose primaquine are significantly lower (∼3%) than estimated previously.
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Affiliation(s)
- Aimee R Taylor
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA, 02115, USA.
- Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA.
| | - James A Watson
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand.
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK.
| | - Cindy S Chu
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK
- Shoklo Malaria Research Unit, Mae Sot, Tak Province, 63110, Thailand
| | - Kanokpich Puaprasert
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
| | - Jureeporn Duanguppama
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
| | - Nicholas P J Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK
| | - Francois Nosten
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK
- Shoklo Malaria Research Unit, Mae Sot, Tak Province, 63110, Thailand
| | - Daniel E Neafsey
- Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Caroline O Buckee
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Mallika Imwong
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
| | - Nicholas J White
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand.
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK.
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5
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Feachem RGA, Chen I, Akbari O, Bertozzi-Villa A, Bhatt S, Binka F, Boni MF, Buckee C, Dieleman J, Dondorp A, Eapen A, Sekhri Feachem N, Filler S, Gething P, Gosling R, Haakenstad A, Harvard K, Hatefi A, Jamison D, Jones KE, Karema C, Kamwi RN, Lal A, Larson E, Lees M, Lobo NF, Micah AE, Moonen B, Newby G, Ning X, Pate M, Quiñones M, Roh M, Rolfe B, Shanks D, Singh B, Staley K, Tulloch J, Wegbreit J, Woo HJ, Mpanju-Shumbusho W. Malaria eradication within a generation: ambitious, achievable, and necessary. Lancet 2019; 394:1056-1112. [PMID: 31511196 DOI: 10.1016/s0140-6736(19)31139-0] [Citation(s) in RCA: 187] [Impact Index Per Article: 37.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 04/26/2019] [Accepted: 05/07/2019] [Indexed: 01/04/2023]
Affiliation(s)
- Richard G A Feachem
- Global Health Group, University of California San Francisco, San Francisco, CA, USA
| | - Ingrid Chen
- Global Health Group, University of California San Francisco, San Francisco, CA, USA.
| | - Omar Akbari
- Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Amelia Bertozzi-Villa
- Malaria Atlas Project, University of Oxford, Oxford, UK; Institute for Disease Modeling, Bellevue, WA, USA
| | - Samir Bhatt
- Malaria Atlas Project, University of Oxford, Oxford, UK
| | - Fred Binka
- School of Public Health, University of Health and Allied Sciences, Ho, Ghana
| | - Maciej F Boni
- Center for Infectious Disease Dynamics, Department of Biology, Penn State, University Park, PA, USA
| | - Caroline Buckee
- Department of Epidemiology, Harvard TH Chan School of Public Health, Boston, MA, USA
| | - Joseph Dieleman
- Institute for Health Metrics, University of Washington, Seattle, WA, USA
| | - Arjen Dondorp
- Mahidol-Oxford Tropical Medicine Research Unit, Bangkok, Thailand
| | - Alex Eapen
- National Institute of Malaria Research, Chennai, India
| | - Neelam Sekhri Feachem
- Institute for Global Health Sciences, University of California San Francisco, San Francisco, CA, USA
| | - Scott Filler
- The Global Fund to Fight AIDS, Tuberculosis and Malaria, Geneva, Switzerland
| | - Peter Gething
- Malaria Atlas Project, University of Oxford, Oxford, UK
| | - Roly Gosling
- Global Health Group, University of California San Francisco, San Francisco, CA, USA
| | - Annie Haakenstad
- Institute for Health Metrics, University of Washington, Seattle, WA, USA
| | - Kelly Harvard
- Global Health Group, University of California San Francisco, San Francisco, CA, USA
| | - Arian Hatefi
- Department of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Dean Jamison
- Institute for Global Health Sciences, University of California San Francisco, San Francisco, CA, USA
| | - Kate E Jones
- Department of Genetics, Evolution and Environment, University College London, London, UK
| | | | | | - Altaf Lal
- Sun Pharma Industries, Mumbai, India
| | - Erika Larson
- Global Health Group, University of California San Francisco, San Francisco, CA, USA
| | - Margaret Lees
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, CA, USA
| | - Neil F Lobo
- Global Health Group, University of California San Francisco, San Francisco, CA, USA
| | - Angela E Micah
- Institute for Health Metrics, University of Washington, Seattle, WA, USA
| | - Bruno Moonen
- Bill & Melinda Gates Foundation, Seattle, WA, USA
| | - Gretchen Newby
- Global Health Group, University of California San Francisco, San Francisco, CA, USA
| | - Xiao Ning
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, China
| | - Muhammad Pate
- Duke Global Health Institute, Duke University, Durham, NC, USA
| | - Martha Quiñones
- Department of Public Health, Universidad Nacional de Colombia, Bogota, Colombia
| | - Michelle Roh
- Global Health Group, University of California San Francisco, San Francisco, CA, USA
| | - Ben Rolfe
- Asia Pacific Leaders Malaria Alliance, Singapore
| | | | - Balbir Singh
- Malaria Research Center, University Malaysia Sarawak, Sarawak, Malaysia
| | | | | | - Jennifer Wegbreit
- Global Health Group, University of California San Francisco, San Francisco, CA, USA
| | - Hyun Ju Woo
- Global Health Group, University of California San Francisco, San Francisco, CA, USA
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6
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Genomic Analyses Reveal the Common Occurrence and Complexity of Plasmodium vivax Relapses in Cambodia. mBio 2018; 9:mBio.01888-17. [PMID: 29362233 PMCID: PMC5784252 DOI: 10.1128/mbio.01888-17] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plasmodium vivax parasites have a unique dormant stage that can cause relapses weeks or months after the initial infection. These dormant parasites are among the main challenges of vivax malaria control as they constitute a reservoir that is difficult to eliminate. Since field studies are confounded by reinfections and possible recrudescence of drug-resistant parasites, most analyses of P. vivax relapses have focused on travelers returning from regions of malaria endemicity. However, it is not clear whether these individuals accurately recapitulate the relapse patterns of repeatedly infected individuals residing in areas of endemicity. Here, we present analyses of vivax malaria patients enrolled in a tightly controlled field study in Cambodia. After antimalarial drug treatment was administered, we relocated 20 individuals to a nontransmission area and followed them for 60 days, with blood collection performed every second day. Our analyses reveal that 60% of the patients relapsed during the monitoring period. Using whole-genome sequencing and high-throughput genotyping, we showed that relapses in Cambodia are often polyclonal and that the relapsing parasites harbor various degrees of relatedness to the parasites present in the initial infection. Our analyses also showed that clone populations differed dynamically, with new clones emerging during the course of the relapsing infections. Overall, our study data show that it is possible to investigate the patterns, dynamics, and diversity of P. vivax relapses of individuals living in a region of malaria endemicity and reveal that P. vivax relapses are much more pervasive and complex than previously considered. (This study has been registered at ClinicalTrials.gov under registration no. NCT02118090)IMPORTANCEP. vivax parasites can remain dormant in the liver and relapse weeks or months after the initial infection, greatly complicating malaria control and elimination efforts. The few investigations of this dormant stage have relied on travelers and military personnel returning from areas of malaria endemicity. However, it is not clear whether these individuals, exposed to a limited number of infections, accurately represent the patterns of relapses of individuals living in areas of endemicity, who are repeatedly infected by P. vivax parasites. Our study combined tightly controlled fieldwork with comprehensive genomic analyses, and our report provides a first opportunity to investigate the patterns, dynamics, and diversity of P. vivax relapses directly with individuals living in areas of endemicity.
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