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Abla N, Marrast AC, Jambert E, Richardson N, Duparc S, Almond L, Rowland Yeo K, Pan X, Tarning J, Zhao P, Culpepper J, Waitt C, Koldeweij C, Cole S, Butler AS, Khier S, Möhrle JJ, El Gaaloul M. Addressing health equity for breastfeeding women: primaquine for Plasmodium vivax radical cure. Malar J 2024; 23:287. [PMID: 39334094 PMCID: PMC11438061 DOI: 10.1186/s12936-024-05112-9] [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: 05/02/2024] [Accepted: 09/13/2024] [Indexed: 09/30/2024] Open
Abstract
Plasmodium vivax malaria remains a global health challenge, with approximately 6.9 million estimated cases in 2022. The parasite has a dormant liver stage, the hypnozoite, which reactivates to cause repeated relapses over weeks, months, or years. These relapses erode patient health, contribute to the burden of malaria, and promote transmission. Radical cure to prevent relapses requires administration of an 8-aminoquinoline, either primaquine or tafenoquine. However, malaria treatment guidelines updated by the World Health Organization (WHO) in October 2023 restrict primaquine use for women breastfeeding children < 6 months of age, or women breastfeeding older children if their child is G6PD deficient or if the child's G6PD status is unknown. Primaquine restrictions assume that 8-aminoquinoline exposures in breast milk would be sufficient to cause haemolysis in the nursing infant should they be G6PD deficient. WHO recommendations for tafenoquine are awaited. Notably, the WHO recommends that infants are breastfed for the first 2 years of life, and exclusively until 6 months old. Repeated pregnancies, followed by extended breastfeeding leaves women in P. vivax endemic regions potentially vulnerable to relapses for many years. This puts women's health at risk, increases the malaria burden, and perpetuates transmission, hindering malaria control and elimination. The benefits of lifting restrictions on primaquine administration to breastfeeding women are significant, avoiding the adverse consequences of repeated episodes of acute malaria, such as severe anaemia. Recent data challenge the restriction of primaquine in breastfeeding women. Clinical pharmacokinetic data in breastfeeding infants ≥ 28 days old show that the exposure to primaquine is very low and less than 1% of the maternal exposure, indicating negligible risk to infants, irrespective of their G6PD status. Physiologically-based pharmacokinetic modelling complements the clinical data, predicting minimal primaquine exposure to infants and neonates via breast milk from early post-partum. This article summarizes the clinical and modelling evidence for a favourable benefit:risk evaluation of P. vivax radical cure with primaquine for breastfeeding women without the need for infant G6PD testing, supporting a change in policy. This adjustment to current treatment guidelines would support health equity in regard to effective interventions to protect women and their children, enhance malaria control strategies, and advance P. vivax elimination.
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Affiliation(s)
- Nada Abla
- MMV Medicines for Malaria Venture, 20 Route de Pré-Bois, 1215, Geneva 15, Switzerland.
| | - Anne Claire Marrast
- MMV Medicines for Malaria Venture, 20 Route de Pré-Bois, 1215, Geneva 15, Switzerland
| | - Elodie Jambert
- MMV Medicines for Malaria Venture, 20 Route de Pré-Bois, 1215, Geneva 15, Switzerland
| | | | - Stephan Duparc
- MMV Medicines for Malaria Venture, 20 Route de Pré-Bois, 1215, Geneva 15, Switzerland
| | - Lisa Almond
- Certara Predictive Technologies, Simcyp Division, Sheffield, UK
| | | | - Xian Pan
- Certara Predictive Technologies, Simcyp Division, Sheffield, UK
| | - Joel Tarning
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Nuffield Department of Clinical Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Ping Zhao
- Bill & Melinda Gates Foundation, Seattle, WA, USA
| | | | - Catriona Waitt
- Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool, UK
- Infectious Diseases Institute, Makerere University College of Health Sciences, Kampala, Uganda
| | - Charlotte Koldeweij
- Division of Pharmacology Toxicology, Department of Pharmacy, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Susan Cole
- Medicines and Healthcare products Regulatory Agency (MHRA), 10 South Colonnade, London, UK
| | - Andrew S Butler
- Medicines and Healthcare products Regulatory Agency (MHRA), 10 South Colonnade, London, UK
| | - Sonia Khier
- Pharmacokinetic and Modelling Department, School of Pharmacy, IMAG, CNRS, INRIA, UMR 5149, University of Montpellier, Montpellier, France
| | - Jörg J Möhrle
- MMV Medicines for Malaria Venture, 20 Route de Pré-Bois, 1215, Geneva 15, Switzerland
| | - Myriam El Gaaloul
- MMV Medicines for Malaria Venture, 20 Route de Pré-Bois, 1215, Geneva 15, Switzerland
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Drysdale M, Tan L, Martin A, Fuhrer IB, Duparc S, Sharma H. Plasmodium vivax in Children: Hidden Burden and Conspicuous Challenges, a Narrative Review. Infect Dis Ther 2023; 12:33-51. [PMID: 36378465 PMCID: PMC9868225 DOI: 10.1007/s40121-022-00713-w] [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: 06/29/2022] [Accepted: 10/05/2022] [Indexed: 11/16/2022] Open
Abstract
There has been progress towards decreasing malaria prevalence globally; however, Plasmodium vivax has been less responsive to elimination efforts compared with Plasmodium falciparum. P. vivax malaria remains a serious public health concern in regions where it is the dominant species (South and South-East Asia, the Eastern Mediterranean region, and South America) and is increasingly recognized for its contribution to overall morbidity and mortality worldwide. The incidence of P. vivax decreases with increasing age owing to rapidly acquired clinical immunity and there is a disproportionate burden of P. vivax in infants and children, who remain highly vulnerable to severe disease, recurrence, and anemia with associated developmental impacts. Diagnosis is sometimes difficult owing to the sensitivity of diagnostic tests to detect low levels of parasitemia. Additionally, the propensity of P. vivax to relapse following reactivation of dormant hypnozoites in the liver contributes to disease recurrence in infants and children, and potentiates morbidity and transmission. The 8-aminoquinolines, primaquine and tafenoquine, provide radical cure (relapse prevention). However, the risk of hemolysis in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency necessitates testing prior to administration of 8-aminoquinolines, which has limited their uptake. Additional challenges include lack of availability of pediatric dose formulations and problems with adherence to primaquine owing to the length of treatment recommended. A paucity of data and studies specific to pediatric P. vivax malaria impacts the ability to deliver targeted interventions. It is imperative that P. vivax in infants and children be the focus of future research, control initiatives, and anti-malarial drug development.
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Affiliation(s)
| | - Lionel Tan
- GSK, 980 Great West Road, Brentford, TW8 9GS Middlesex UK
| | - Ana Martin
- GSK, 980 Great West Road, Brentford, TW8 9GS Middlesex UK
| | | | | | - Hema Sharma
- GSK, 980 Great West Road, Brentford, TW8 9GS Middlesex UK
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3
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Corder RM, Arez AP, Ferreira MU. Individual variation in Plasmodium vivax malaria risk: Are repeatedly infected people just unlucky? PLoS Negl Trop Dis 2023; 17:e0011020. [PMID: 36634044 PMCID: PMC9836309 DOI: 10.1371/journal.pntd.0011020] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Extensive research has examined why some people have frequent Plasmodium falciparum malaria episodes in sub-Saharan Africa while others remain free of disease most of the time. In contrast, malaria risk heterogeneity remains little studied in regions where P. vivax is the dominant species. Are repeatedly infected people in vivax malaria settings such as the Amazon just unlucky? Here, we briefly review evidence that human genetic polymorphism and acquired immunity after repeated exposure to parasites can modulate the risk of P. vivax infection and disease in predictable ways. One-fifth of the hosts account for 80% or more of the community-wide vivax malaria burden and contribute disproportionally to onward transmission, representing a priority target of more intensive interventions to achieve malaria elimination. Importantly, high-risk individuals eventually develop clinical immunity, even in areas with very low or residual malaria transmission, and may constitute a large but silent parasite reservoir.
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Affiliation(s)
- Rodrigo M. Corder
- Department of Epidemiology and Biostatistics, University of California, Berkeley School of Public Health, Berkeley, California, United States of America
| | - Ana Paula Arez
- Global Health and Tropical Medicine (GHTM), institute of Hygiene and Tropical Medicine, NOVA University of Lisbon, Lisbon, Portugal
| | - Marcelo U. Ferreira
- Global Health and Tropical Medicine (GHTM), institute of Hygiene and Tropical Medicine, NOVA University of Lisbon, Lisbon, Portugal
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
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Xu Y, Dong Y, Deng Y, Huang H, Chen M, Liu Y, Wu J, Zhang C, Zheng W. Molecular identification of vivax malaria relapse patients in the Yunnan Province based on homology analysis of the Plasmodium vivax circumsporozoite protein gene. Parasitol Res 2023; 122:85-96. [PMID: 36334150 PMCID: PMC9816221 DOI: 10.1007/s00436-022-07700-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Accepted: 10/18/2022] [Indexed: 11/06/2022]
Abstract
More than 85% of the malaria burden in the Yunnan Province is caused by imported vivax malaria, and Yunnan is also where the majority of vivax malaria patients are diagnosed in China. Timely removal of the infection sources of Plasmodium vivax and its breeding environment remains the key to eliminating the secondary transmission of imported malaria. To that end, blood samples were collected from cases diagnosed and revalidated as single species infection with P. vivax in the Yunnan Province from 2013 to 2020. Specifically, samples from vivax malaria patients with suspected relapses episodes were subjected to PCR amplification, product sequencing, and analysis of the P. vivax circumsporozoite protein (pvcsp) gene. In total, 77 suspected relapse patients were identified out of 2484 cases infected with P. vivax, with a total of 81 recurrent episodes. A total of 156 CDS (coding DNA sequence) chains were obtained through PCR amplification and sequencing of the pvcsp gene from 159 blood samples, 121 of which can be matched to the paired sequences of 59 vivax malaria patients with both primary attack and recurrent experience. Of the 59 pairs of pvcsp gene sequences, every one of 31 pairs showed only one haplotype and no variant sites (VS), meaning every two paired sequence was completely homologous. Every one of the remaining 28 paired sequences had two haplotypes but no length polymorphism, indicating that the paired sequences was "weakly heterologous" with no fragment insertions (or deletions). All 59 vivax malaria patients with recurrences were caused by the activation of P. vivax hypnozoites originated from the same population as the primary infection. The paired analysis of the similarity between high variant genes allowed the identification of relapse episodes caused by P. vivax homologous hypnozoites and also demonstrated pvcsp gene as one of the candidate molecular markers for tracing infection origin.
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Affiliation(s)
- Yanchun Xu
- Yunnan Institute of Parasitic Diseases Control, Yunnan Provincial Key Laboratory of Vector-Borne Diseases Control and Research, Yunnan Centre of Malaria Research, Pu'er, 665000, China
| | - Ying Dong
- Yunnan Institute of Parasitic Diseases Control, Yunnan Provincial Key Laboratory of Vector-Borne Diseases Control and Research, Yunnan Centre of Malaria Research, Pu'er, 665000, China.
| | - Yan Deng
- Yunnan Institute of Parasitic Diseases Control, Yunnan Provincial Key Laboratory of Vector-Borne Diseases Control and Research, Yunnan Centre of Malaria Research, Pu'er, 665000, China
| | - Herong Huang
- Department of Basic Medical Sciences, Clinical College of Anhui Medical University, Hefei, 230031, China
| | - Mengni Chen
- Yunnan Institute of Parasitic Diseases Control, Yunnan Provincial Key Laboratory of Vector-Borne Diseases Control and Research, Yunnan Centre of Malaria Research, Pu'er, 665000, China
| | - Yan Liu
- Yunnan Institute of Parasitic Diseases Control, Yunnan Provincial Key Laboratory of Vector-Borne Diseases Control and Research, Yunnan Centre of Malaria Research, Pu'er, 665000, China
| | - Jing Wu
- Yunnan Institute of Parasitic Diseases Control, Yunnan Provincial Key Laboratory of Vector-Borne Diseases Control and Research, Yunnan Centre of Malaria Research, Pu'er, 665000, China
| | - Canglin Zhang
- Yunnan Institute of Parasitic Diseases Control, Yunnan Provincial Key Laboratory of Vector-Borne Diseases Control and Research, Yunnan Centre of Malaria Research, Pu'er, 665000, China
| | - Webi Zheng
- Center for Disease Control and Prevention, Baoshan, 678000, China.
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Stadler E, Cromer D, Mehra S, Adekunle AI, Flegg JA, Anstey NM, Watson JA, Chu CS, Mueller I, Robinson LJ, Schlub TE, Davenport MP, Khoury DS. Population heterogeneity in Plasmodium vivax relapse risk. PLoS Negl Trop Dis 2022; 16:e0010990. [PMID: 36534705 PMCID: PMC9810152 DOI: 10.1371/journal.pntd.0010990] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 01/03/2023] [Accepted: 11/28/2022] [Indexed: 12/23/2022] Open
Abstract
A key characteristic of Plasmodium vivax parasites is their ability to adopt a latent liver-stage form called hypnozoites, able to cause relapse of infection months or years after a primary infection. Relapses of infection through hypnozoite activation are a major contributor to blood-stage infections in P vivax endemic regions and are thought to be influenced by factors such as febrile infections which may cause temporary changes in hypnozoite activation leading to 'temporal heterogeneity' in reactivation risk. In addition, immunity and variation in exposure to infection may be longer-term characteristics of individuals that lead to 'population heterogeneity' in hypnozoite activation. We analyze data on risk of P vivax in two previously published data sets from Papua New Guinea and the Thailand-Myanmar border region. Modeling different mechanisms of reactivation risk, we find strong evidence for population heterogeneity, with 30% of patients having almost 70% of all P vivax infections. Model fitting and data analysis indicates that individual variation in relapse risk is a primary source of heterogeneity of P vivax risk of recurrences. Trial Registration: ClinicalTrials.gov NCT01640574, NCT01074905, NCT02143934.
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Affiliation(s)
- Eva Stadler
- The Kirby Institute, UNSW Sydney, Sydney, Australia
| | | | - Somya Mehra
- School of Mathematics and Statistics, University of Melbourne, Melbourne, Australia
| | - Adeshina I. Adekunle
- Australian Institute of Tropical Health and Medicine, James Cook University, Townsville, Australia
| | - Jennifer A. Flegg
- School of Mathematics and Statistics, University of Melbourne, Melbourne, Australia
| | | | - James A. Watson
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Headington, Oxford, United Kingdom
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Cindy S. Chu
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Headington, Oxford, United Kingdom
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Ivo Mueller
- Population Health & Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Leanne J. Robinson
- Population Health & Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
- Burnet Institute, Melbourne, Victoria, Australia
- PNG Institute of Medical Research, Madang, Papua New Guinea
| | - Timothy E. Schlub
- The Kirby Institute, UNSW Sydney, Sydney, Australia
- Sydney School of Public Health, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
| | | | - David S. Khoury
- The Kirby Institute, UNSW Sydney, Sydney, Australia
- * E-mail:
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Barros LB, Calil PR, Rodrigues PT, Tonini J, Fontoura PS, Sato PM, Cardoso MA, Russo MWDAA, Cavasini CE, Fernandes ARDJ, Ferreira MU. Clinically silent Plasmodium vivax infections in native Amazonians of northwestern Brazil: acquired immunity or low parasite virulence? Mem Inst Oswaldo Cruz 2022; 117:e220175. [PMID: 36542002 PMCID: PMC9756956 DOI: 10.1590/0074-02760220175] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 11/17/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Malaria remains common among native Amazonians, challenging Brazil's elimination efforts. OBJECTIVES We examined the epidemiology of malaria in riverine populations of the country's main hotspot - the upper Juruá Valley in Acre state, close to the Brazil-Peru border, where Plasmodium vivax accounts for > 80% of cases. METHODS Participants (n = 262) from 10 villages along the Azul River were screened for malaria parasites by microscopy and genus-specific, cytochrome b (cytb) gene-based polymerase chain reaction. Positive samples were further tested with quantitative TaqMan assays targeting P. vivax- and P. falciparum-specific cytb domains. We used multiple logistic regression analysis to identify independent correlates of P. vivax infection. FINDINGS Microscopy detected only one P. vivax and two P. falciparum infections. TaqMan assays detected 33 P. vivax infections (prevalence, 11.1%), 78.1% of which asymptomatic, with a median parasitaemia of 34/mL. Increasing age, male sex and use of insecticide-treated bed nets were significant predictors of elevated P. vivax malaria risk. Children and adults were similarly likely to remain asymptomatic once infected. MAIN CONCLUSIONS Our findings are at odds with the hypothesis of age-related clinical immunity in native Amazonians. The low virulence of local parasites is suggested as an alternative explanation for subclinical infections in isolated populations.
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Affiliation(s)
- Luiza Barbosa Barros
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Parasitologia, São Paulo, SP, Brasil
| | - Priscila Rodrigues Calil
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Parasitologia, São Paulo, SP, Brasil
| | - Priscila Thihara Rodrigues
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Parasitologia, São Paulo, SP, Brasil
| | - Juliana Tonini
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Parasitologia, São Paulo, SP, Brasil
| | - Pablo Secato Fontoura
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Parasitologia, São Paulo, SP, Brasil
| | - Priscila Moraes Sato
- Universidade de São Paulo, Faculdade de Saúde Pública, Departamento de Nutrição, São Paulo, SP, Brasil
| | - Marly Augusto Cardoso
- Universidade de São Paulo, Faculdade de Saúde Pública, Departamento de Nutrição, São Paulo, SP, Brasil
| | | | - Carlos Eduardo Cavasini
- Faculdade de Medicina de São José do Rio Preto, Departamento de Doenças Dermatológicas, Infecciosas e Parasitárias, São José do Rio Preto, SP, Brasil
| | | | - Marcelo Urbano Ferreira
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Parasitologia, São Paulo, SP, Brasil,Universidade Nova de Lisboa, Instituto de Higiene e Medicina Tropical, Lisboa, Portugal,+ Corresponding author: /
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7
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Habtamu K, Petros B, Yan G. Plasmodium vivax: the potential obstacles it presents to malaria elimination and eradication. Trop Dis Travel Med Vaccines 2022; 8:27. [PMID: 36522671 PMCID: PMC9753897 DOI: 10.1186/s40794-022-00185-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 11/23/2022] [Indexed: 12/23/2022] Open
Abstract
Initiatives to eradicate malaria have a good impact on P. falciparum malaria worldwide. P. vivax, however, still presents significant difficulties. This is due to its unique biological traits, which, in comparison to P. falciparum, pose serious challenges for malaria elimination approaches. P. vivax's numerous distinctive characteristics and its ability to live for weeks to years in liver cells in its hypnozoite form, which may elude the human immune system and blood-stage therapy and offer protection during mosquito-free seasons. Many malaria patients are not fully treated because of contraindications to primaquine use in pregnant and nursing women and are still vulnerable to P. vivax relapses, although there are medications that could radical cure P. vivax. Additionally, due to CYP2D6's highly variable genetic polymorphism, the pharmacokinetics of primaquine may be impacted. Due to their inability to metabolize PQ, some CYP2D6 polymorphism alleles can cause patients to not respond to treatment. Tafenoquine offers a radical treatment in a single dose that overcomes the potentially serious problem of poor adherence to daily primaquine. Despite this benefit, hemolysis of the early erythrocytes continues in individuals with G6PD deficiency until all susceptible cells have been eliminated. Field techniques such as microscopy or rapid diagnostic tests (RDTs) miss the large number of submicroscopic and/or asymptomatic infections brought on by reticulocyte tropism and the low parasitemia levels that accompany it. Moreover, P. vivax gametocytes grow more quickly and are much more prevalent in the bloodstream. P. vivax populations also have a great deal of genetic variation throughout their genome, which ensures evolutionary fitness and boosts adaptation potential. Furthermore, P. vivax fully develops in the mosquito faster than P. falciparum. These characteristics contribute to parasite reservoirs in the human population and facilitate faster transmission. Overall, no genuine chance of eradication is predicted in the next few years unless new tools for lowering malaria transmission are developed (i.e., malaria elimination and eradication). The challenging characteristics of P. vivax that impede the elimination and eradication of malaria are thus discussed in this article.
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Affiliation(s)
- Kassahun Habtamu
- Department of Microbial, Cellular & Molecular Biology, Addis Ababa University, Addis Ababa, Ethiopia
- Menelik II Medical & Health Science College, Addis Ababa, Ethiopia
| | - Beyene Petros
- Department of Microbial, Cellular & Molecular Biology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Guiyun Yan
- Program in Public Health, University of California at Irvine, Irvine, CA 92697 USA
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Ferreira MU, Gamboa D, Torres K, Rodriguez-Ferrucci H, Soto-Calle VE, Pardo K, Fontoura PS, Tomko SS, Gazzinelli RT, Conn JE, Castro MC, Llanos-Cuentas A, Vinetz JM. Evidence-Based Malaria Control and Elimination in the Amazon: Input from the International Center of Excellence in Malaria Research Network in Peru and Brazil. Am J Trop Med Hyg 2022; 107:160-167. [PMID: 36228907 PMCID: PMC9662230 DOI: 10.4269/ajtmh.21-1272] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 03/15/2022] [Indexed: 11/07/2022] Open
Abstract
Malaria remains endemic in 17 countries in the Americas, where 723,000 cases were reported in 2019. The majority (> 90%) of the regional malaria burden is found within the Amazon Basin, which includes nine countries and territories in South America. Locally generated evidence is critical to provide information to public health decision makers upon which the design of efficient and regionally directed malaria control and elimination programs can be built. Plasmodium vivax is the predominant malaria parasite in the Amazon Basin. This parasite species appears to be more resilient to malaria control strategies worldwide. Asymptomatic Plasmodium infections constitute a potentially infectious reservoir that is typically missed by routine microscopy-based surveillance and often remains untreated. The primary Amazonian malaria vector, Nyssorhynchus (formerly Anopheles) darlingi, has changed its behavior to feed and rest predominantly outdoors, reducing the efficiency of core vector control measures such as indoor residual spraying and distribution of long-lasting insecticide-treated bed nets. We review public health implications of recent field-based research carried out by the Amazonia International Center of Excellence in Malaria Research in Peru and Brazil. We discuss the relative role of traditional and novel tools and strategies for better malaria control and elimination across the Amazon, including improved diagnostic methods, new anti-relapse medicines, and biological larvicides, and emphasize the need to integrate research and public health policymaking.
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Affiliation(s)
- Marcelo U. Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- Address correspondence to Marcelo U. Ferreira, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, Cidade Universitária, 05508-900 São Paulo, Brazil, E-mail: or Dionicia Gamboa, Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Av. Honorio Delgado 430, San Martín de Porres, Lima, Peru, E-mail:
| | - Dionicia Gamboa
- Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
- Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
- Address correspondence to Marcelo U. Ferreira, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, Cidade Universitária, 05508-900 São Paulo, Brazil, E-mail: or Dionicia Gamboa, Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Av. Honorio Delgado 430, San Martín de Porres, Lima, Peru, E-mail:
| | - Katherine Torres
- Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
- Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | | | - Veronica E. Soto-Calle
- Dirección de Prevención y Control de Enfermedades Metaxénicas y Zoonosis, Ministerio de Salud, Lima, Peru
| | - Karim Pardo
- Universidad de Ciencias Aplicadas and Ejecutiva Adjunta II, Despacho Viceministerial de Salud Pública, Ministerio de Salud, Lima, Peru
| | - Pablo S. Fontoura
- Coordenação-Geral de Arboviroses, Secretaria de Vigilância em Saúde, Ministério da Saúde, Brasília, Brazil
| | - Sheena S. Tomko
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ricardo T. Gazzinelli
- Instituto de Pesquisas Rene Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Brazil
- Division of Infectious Disease and immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts
- Plataforma de Medicina Translacional, Fundação Oswaldo Cruz, Ribeirão Preto, Brazil
| | - Jan E. Conn
- Department of Biomedical Sciences, School of Public Health, University at Albany, State University of New York, Albany, New York
- Wadsworth Center, New York State Department of Health, Albany, New York
| | - Marcia C. Castro
- Department of Global Health and Population, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
| | - Alejandro Llanos-Cuentas
- Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Joseph M. Vinetz
- Laboratorios de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
- Section of Infectious Diseases, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut
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Hypnozoite dynamics for Plasmodium vivax malaria: the epidemiological effects of radical cure. J Theor Biol 2022; 537:111014. [PMID: 35016895 DOI: 10.1016/j.jtbi.2022.111014] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 11/30/2021] [Accepted: 01/03/2022] [Indexed: 01/27/2023]
Abstract
Malaria is a mosquito-borne disease with a devastating global impact. Plasmodium vivax is a major cause of human malaria beyond sub-Saharan Africa. Relapsing infections, driven by a reservoir of liver-stage parasites known as hypnozoites, present unique challenges for the control of P. vivax malaria. Following indeterminate dormancy periods, hypnozoites may activate to trigger relapses. Clearance of the hypnozoite reservoir through drug treatment (radical cure) has been proposed as a potential tool for the elimination of P. vivax malaria. Here, we introduce a stochastic, within-host model to jointly characterise hypnozoite and infection dynamics for an individual in a general transmission setting, allowing for radical cure. We begin by extending an existing activation-clearance model for a single hypnozoite, adapted to both short- and long-latency strains, to include drug treatment. We then embed this activation-clearance model in an epidemiological framework accounting for repeated mosquito inoculation and the administration of radical cure. By constructing an open network of infinite server queues, we derive analytic expressions for several quantities of epidemiological significance, including the size of the hypnozoite reservoir; the relapse rate; the relative contribution of relapses to the infection burden; the distribution of multiple infections; the cumulative number of recurrences over time, and the time to first recurrence following drug treatment. We derive from first principles the functional dependence between within-host and transmission parameters and patterns of blood- and liver-stage infection, whilst allowing for treatment under a mass drug administration regime. To yield population-level insights, our analytic within-host distributions can be embedded in multiscale models. Our work thus contributes to the epidemiological understanding of the effects of radical cure on P. vivax malaria.
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Pincelli A, Cardoso MA, Malta MB, Johansen IC, Corder RM, Nicolete VC, Soares IS, Castro MC, Ferreira MU. Low-level Plasmodium vivax exposure, maternal antibodies, and anemia in early childhood: Population-based birth cohort study in Amazonian Brazil. PLoS Negl Trop Dis 2021; 15:e0009568. [PMID: 34264946 PMCID: PMC8282015 DOI: 10.1371/journal.pntd.0009568] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 06/16/2021] [Indexed: 11/26/2022] Open
Abstract
Background Malaria causes significant morbidity and mortality in children under 5 years of age in sub-Saharan Africa and the Asia-Pacific region. Neonates and young infants remain relatively protected from clinical disease and the transplacental transfer of maternal antibodies is hypothesized as one of the protective factors. The adverse health effects of Plasmodium vivax malaria in early childhood–traditionally viewed as a benign infection–remain largely neglected in relatively low-endemicity settings across the Amazon. Methodology/Principal findings Overall, 1,539 children participating in a birth cohort study in the main transmission hotspot of Amazonian Brazil had a questionnaire administered, and blood sampled at the two-year follow-up visit. Only 7.1% of them experienced malaria confirmed by microscopy during their first 2 years of life– 89.1% of the infections were caused by P. vivax. Young infants appear to be little exposed to, or largely protected from infection, but children >12 months of age become as vulnerable to vivax malaria as their mothers. Few (1.4%) children experienced ≥4 infections during the 2-year follow-up, accounting for 43.4% of the overall malaria burden among study participants. Antenatal malaria diagnosed by microscopy during pregnancy or by PCR at delivery emerged as a significant correlate of subsequent risk of P. vivax infection in the offspring (incidence rate ratio, 2.58; P = 0.002), after adjusting for local transmission intensity. Anti-P. vivax antibodies measured at delivery do not protect mothers from subsequent malaria; whether maternal antibodies transferred to the fetus reduce early malaria risk in children remains undetermined. Finally, recent and repeated vivax malaria episodes in early childhood are associated with increased risk of anemia at the age of 2 years in this relatively low-endemicity setting. Conclusions/Significance Antenatal infection increases the risk of vivax malaria in the offspring and repeated childhood P. vivax infections are associated with anemia at the age of 2 years. Plasmodium vivax malaria causes frequent hospital admissions of infants and toddlers in areas of intense transmission in the Asia-Pacific region, often due to severe anemia, but its epidemiology and burden have been understudied in children from other endemic settings. Here we characterize the cumulative impact of P. vivax infections in infants and toddlers exposed to relatively low levels of malaria transmission in the Brazilian Amazon. We have previously shown that vivax malaria in pregnancy is associated with increased risk of maternal anemia and impaired fetal growth in this population. Now we show that the adverse effects of malaria extend to early childhood. Children born to mothers who had one or more infections during pregnancy are at an elevated risk of P. vivax malaria in their early life, although the transfer of maternal antibodies to the fetus may provide some short-term protection. Children who are repeatedly infected with P. vivax since birth are more likely to be anemic at the age of 2 years. These findings further challenge the traditional view of vivax malaria as a relatively benign infection in pregnancy and early childhood in the Amazon.
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Affiliation(s)
- Anaclara Pincelli
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Marly A. Cardoso
- Department of Nutrition, School of Public Health, University of São Paulo, São Paulo, Brazil
| | - Maíra B. Malta
- Department of Nutrition, School of Public Health, University of São Paulo, São Paulo, Brazil
- Graduate Program in Collective Health, Catholic University of Santos, Santos, Brazil
| | - Igor C. Johansen
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Rodrigo M. Corder
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Vanessa C. Nicolete
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Irene S. Soares
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
| | - Marcia C. Castro
- Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America
| | - Marcelo U. Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- * E-mail:
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Ferreira MU, Nobrega de Sousa T, Rangel GW, Johansen IC, Corder RM, Ladeia-Andrade S, Gil JP. Monitoring Plasmodium vivax resistance to antimalarials: Persisting challenges and future directions. Int J Parasitol Drugs Drug Resist 2021; 15:9-24. [PMID: 33360105 PMCID: PMC7770540 DOI: 10.1016/j.ijpddr.2020.12.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 11/27/2020] [Accepted: 12/01/2020] [Indexed: 11/23/2022]
Abstract
Emerging antimalarial drug resistance may undermine current efforts to control and eliminate Plasmodium vivax, the most geographically widespread yet neglected human malaria parasite. Endemic countries are expected to assess regularly the therapeutic efficacy of antimalarial drugs in use in order to adjust their malaria treatment policies, but proper funding and trained human resources are often lacking to execute relatively complex and expensive clinical studies, ideally complemented by ex vivo assays of drug resistance. Here we review the challenges for assessing in vivo P. vivax responses to commonly used antimalarials, especially chloroquine and primaquine, in the presence of confounding factors such as variable drug absorption, metabolism and interaction, and the risk of new infections following successful radical cure. We introduce a simple modeling approach to quantify the relative contribution of relapses and new infections to recurring parasitemias in clinical studies of hypnozoitocides. Finally, we examine recent methodological advances that may render ex vivo assays more practical and widely used to confirm P. vivax drug resistance phenotypes in endemic settings and review current approaches to the development of robust genetic markers for monitoring chloroquine resistance in P. vivax populations.
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Affiliation(s)
- Marcelo U Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil; Global Health and Tropical Medicine, Institute of Hygiene and Tropical Medicine, Nova University of Lisbon, Lisbon, Portugal.
| | - Tais Nobrega de Sousa
- Molecular Biology and Malaria Immunology Research Group, René Rachou Institute, Fiocruz, Belo Horizonte, Brazil
| | - Gabriel W Rangel
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA
| | - Igor C Johansen
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Rodrigo M Corder
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Simone Ladeia-Andrade
- Laboratory of Parasitic Diseases, Oswaldo Cruz Institute, Fiocruz, Rio de Janeiro, Brazil
| | - José Pedro Gil
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, Solna, Sweden
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