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Fontoura PS, Macedo EG, Calil PR, Corder RM, Rodrigues PT, Tonini J, Esquivel FD, Ladeia WA, Fernandes ARJ, Johansen IC, Silva MF, Fernandes AOS, Ladeia-Andrade S, Castro MC, Ferreira MU. Changing Clinical Epidemiology of Plasmodium vivax Malaria as Transmission Decreases: Population-Based Prospective Panel Survey in the Brazilian Amazon. J Infect Dis 2024; 229:947-958. [PMID: 38324758 PMCID: PMC11011196 DOI: 10.1093/infdis/jiad456] [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: 06/03/2023] [Accepted: 10/16/2023] [Indexed: 02/09/2024] Open
Abstract
BACKGROUND Malarial infections are often missed by microscopy, and most parasite carriers are asymptomatic in low-endemicity settings. Whether parasite detectability and its ability to elicit symptoms change as transmission declines remains unclear. METHODS We performed a prospective panel survey with repeated measurements on the same participants over 12 months to investigate whether Plasmodium vivax detectability by microscopy and risk of symptoms upon infection varied during a community-wide larviciding intervention in the Amazon basin of Brazil that markedly reduced vector density. We screened 1096 to 1400 residents in the intervention site for malaria by microscopy and quantitative TaqMan assays at baseline and twice during intervention. RESULTS We found that more P vivax infections than expected from their parasite densities measured by TaqMan assays were missed by microscopy as transmission decreased. At lower transmission, study participants appeared to tolerate higher P vivax loads without developing symptoms. We hypothesize that changes in the ratio between circulating parasites and those that accumulate in the bone marrow and spleen, by avoiding peripheral blood microscopy detection, account for decreased parasite detectability and lower risk of symptoms under low transmission. CONCLUSIONS P vivax infections are more likely to be subpatent and remain asymptomatic as malaria transmission decreases.
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Affiliation(s)
- Pablo S Fontoura
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo
- Secretary of Health Surveillance, Ministry of Health, Brasília, Brazil
| | - Evelyn G Macedo
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo
| | - Priscila R Calil
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo
| | - Rodrigo M Corder
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo
- Divisions of Epidemiology and Biostatistics, Berkeley School of Public Health, University of California
| | - Priscila T Rodrigues
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo
| | - Juliana Tonini
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo
| | - Fabiana D Esquivel
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo
| | - Winni A Ladeia
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo
| | | | - Igor C Johansen
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo
| | - Marcos F Silva
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo
| | - Amanda O S Fernandes
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo
| | | | - Marcia C Castro
- Department of Global Health and Population, Harvard T. H. Chan School of Public Health, Boston, Massachusetts
| | - Marcelo U Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo
- Global Health and Tropical Medicine, Institute of Hygiene and Tropical Medicine, Nova University of Lisbon, Portugal
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Perrotti E, L'Episcopia M, Menegon M, Soares IS, Rosas-Aguirre A, Speybroeck N, LLanos-Cuentas A, Menard D, Ferreira MU, Severini C. Reduced polymorphism of Plasmodium vivax early transcribed membrane protein (PvETRAMP) 11.2. Parasit Vectors 2023; 16:238. [PMID: 37461081 DOI: 10.1186/s13071-023-05851-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 06/27/2023] [Indexed: 07/20/2023] Open
Abstract
BACKGROUND ETRAMP11.2 (PVX_003565) is a well-characterized protein with antigenic potential. It is considered to be a serological marker for diagnostic tools, and it has been suggested as a potential vaccine candidate. Despite its immunological relevance, the polymorphism of the P. vivax ETRAMP11.2 gene (pvetramp11.2) remains undefined. The genetic variability of an antigen may limit the effectiveness of its application as a serological surveillance tool and in vaccine development and, therefore, the aim of this study was to investigate the genetic diversity of pvetramp11.2 in parasite populations from Amazonian regions and worldwide. We also evaluated amino acid polymorphism on predicted B-cell epitopes. The low variability of the sequence encoding PvETRAMP11.2 protein suggests that it would be a suitable marker in prospective serodiagnostic assays for surveillance strategies or in vaccine design against P. vivax malaria. METHODS The pvetramp11.2 of P. vivax isolates collected from Brazil (n = 68) and Peru (n = 36) were sequenced and analyzed to assess nucleotide polymorphisms, allele distributions, population differentiation, genetic diversity and signature of selection. In addition, sequences (n = 104) of seven populations from different geographical regions were retrieved from the PlasmoDB database and included in the analysis to study the worldwide allele distribution. Potential linear B-cell epitopes and their polymorphisms were also explored. RESULTS The multiple alignments of 208 pvetramp11.2 sequences revealed a low polymorphism and a marked geographical variation in allele diversity. Seven polymorphic sites and 11 alleles were identified. All of the alleles were detected in isolates from the Latin American region and five alleles were detected in isolates from the Southeast Asia/Papua New Guinea (SEA/PNG) region. Three alleles were shared by all Latin American populations (H1, H6 and H7). The H1 allele (reference allele from Salvador-1 strain), which was absent in the SEA/PNG populations, was the most represented allele in populations from Brazil (54%) and was also detected at high frequencies in populations from all other Latin America countries (range: 13.0% to 33.3%). The H2 allele was the major allele in SEA/PNG populations, but was poorly represented in Latin America populations (only in Brazil: 7.3%). Plasmodium vivax populations from Latin America showed a marked inter-population genetic differentiation (fixation index [Fst]) in contrast to SEA/PNG populations. Codon bias measures (effective number of codons [ENC] and Codon bias index [CBI]) indicated preferential use of synonymous codons, suggesting selective pressure at the translation level. Only three amino acid substitutions, located in the C-terminus, were detected. Linear B-cell epitope mapping predicted two epitopes in the Sal-1 PvETRAMP11.2 protein, one of which was fully conserved in all of the parasite populations analyzed. CONCLUSIONS We provide an overview of the allele distribution and genetic differentiation of ETRAMP11.2 antigen in P. vivax populations from different endemic areas of the world. The reduced polymorphism and the high degree of protein conservation supports the application of PvETRAMP11.2 protein as a reliable antigen for application in serological assays or vaccine design. Our findings provide useful information that can be used to inform future study designs.
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Affiliation(s)
- Edvige Perrotti
- Department of Infectious Diseases, Istituto Superiore Di Sanità, Rome, Italy.
| | | | - Michela Menegon
- Department of Infectious Diseases, Istituto Superiore Di Sanità, Rome, Italy
| | - Irene S Soares
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
| | - Angel Rosas-Aguirre
- Research Institute of Health and Society (IRSS), Université Catholique de Louvain, Brussels, Belgium
- Instituto de Medicina Tropical "Alexander Von Humboldt", Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Niko Speybroeck
- Research Institute of Health and Society (IRSS), Université Catholique de Louvain, Brussels, Belgium
| | - Alejandro LLanos-Cuentas
- Instituto de Medicina Tropical "Alexander Von Humboldt", Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Didier Menard
- Laboratoire de Parasitologie Et Mycologie Médicale, Les Hôpitaux Universitaires de Strasbourg, Strasbourg, France
- Institut de Parasitologie Et Pathologie Tropicale, Université de Strasbourg, Strasbourg, France
- Malaria Genetics and Resistance Unit-INSERM U1201, Institut Pasteur, Paris, France
| | - Marcelo Urbano Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade NOVA de Lisboa, Lisbon, Portugal
| | - Carlo Severini
- Department of Infectious Diseases, Istituto Superiore Di Sanità, Rome, Italy.
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Ruybal-Pesántez S, Sáenz FE, Deed SL, Johnson EK, Larremore DB, Vera-Arias CA, Tiedje KE, Day KP. Molecular epidemiology of continued Plasmodium falciparum disease transmission after an outbreak in Ecuador. FRONTIERS IN TROPICAL DISEASES 2023. [DOI: 10.3389/fitd.2023.1085862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2023] Open
Abstract
To better understand the factors underlying the continued incidence of clinical episodes of falciparum malaria in E-2025 countries targeting elimination, we characterized the molecular epidemiology of Plasmodium falciparum disease transmission after a clonal outbreak in Ecuador. Here we study disease transmission by documenting the diversity and population structure of the major variant surface antigen of the blood stages of P. falciparum encoded by the var multigene family. We used a high-resolution genotyping method, “varcoding”, involving targeted amplicon sequencing to fingerprint the DBLα encoding region of var genes to describe both antigenic var diversity and var repertoire similarity or relatedness in parasite isolates from clinical cases. We identified nine genetic varcodes in 58 P. falciparum isolates causing clinical disease in 2013-2015. Network analyses revealed that four of the varcodes were highly related to the outbreak varcode, with identification of possible diversification of the outbreak parasites by recombination as seen in three of those varcodes. The majority of clinical cases in Ecuador were associated with parasites with highly related or recombinant varcodes to the outbreak clone and due to local transmission rather than recent importation of parasites from other endemic countries. Sharing of types in Ecuadorian varcodes to those sampled in South American varcodes reflects historical parasite importation of some varcodes, especially from Colombia and Peru. Our findings highlight the translational application of varcoding for outbreak surveillance in epidemic/unstable malaria transmission, such as in E-2025 countries, and point to the need for surveillance of local reservoirs of infection in Ecuador to achieve the malaria elimination goal by 2025.
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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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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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Prolonged Breastfeeding and the Risk of Plasmodium vivax Infection and Clinical Malaria in Early Childhood: A Birth Cohort Study. Pediatr Infect Dis J 2022; 41:793-799. [PMID: 35763695 DOI: 10.1097/inf.0000000000003618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Relatively few Amazonian infants have clinical malaria diagnosed, treated and notified before their first birthday, either because they are little exposed to an infection or remain asymptomatic once infected. Here we measure the proportion of children who have experienced Plasmodium vivax infection and malaria by 2 years of age in the main transmission hotspot of Amazonian Brazil. METHODS We measured IgG antibodies to 3 blood-stage P. vivax antigens at the 1- and 2-year follow-up assessment of 435 participants in a population-based birth cohort. Children's malaria case notifications were retrieved from the electronic database of the Ministry of Health. We used multiple Poisson regression models to identify predictors of serologically proven P. vivax infection and clinical vivax malaria during the first 2 years of life. RESULTS Overall, 23 [5.3%; 95% confidence interval (CI): 3.5-7.8%) children had antibodies to ≥2 antigens detected during at least one follow-up assessment, consistent with past P. vivax infection(s). Fifteen (3.4%; 95% CI: 2.1-5.6%) children had clinical vivax episodes notified during the first 2 years of life; 7 of them were seronegative. We estimate that half of the infections remained unnotified. Children born to women who experienced P. vivax infection during pregnancy were more likely to be infected and develop clinical vivax malaria, while those breast-fed for ≥12 months had their risk of being P. vivax -seropositive (which we take as evidence of blood-stage P. vivax infection during the first 2 years of life) decreased by 79.8% (95% CI: 69.3-86.7%). CONCLUSION P. vivax infections in early childhood are underreported in the Amazon, are associated with anemia at 2 years of age, and appear to be partially prevented by prolonged breastfeeding.
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COVID-19 in Latin America and the Caribbean Region: Symptoms and Morbidities in the Epidemiology of Infection. Curr Opin Pharmacol 2022; 63:102203. [PMID: 35255454 PMCID: PMC8896761 DOI: 10.1016/j.coph.2022.102203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 01/21/2022] [Accepted: 02/01/2022] [Indexed: 01/06/2023]
Abstract
The COVID-19 pandemic has widespread economic and social effects on Latin America (LA) and the Caribbean (CA). This region, which has a high prevalence of chronic diseases, has been one of the most affected during the pandemic. Multiple symptoms and comorbidities are related to distinct COVID-19 outcomes. However, there has been no explanation as to why different patients present with different arrays of clinical presentations. Studies report that similar to comorbidities, each country in LA and the CA has its own particular health issues. Moreover, economic and social features have yet to be studied in detail to obtain a complete perspective of the disease in the region. Herein, the impact of demographic and economic characteristics in LA and the CA on COVID-19 are presented in combination with symptoms and comorbidities related to the disease as important aspects that can influence management and treatment.
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Ferreira MU, Corder RM, Johansen IC, Kattenberg JH, Moreno M, Rosas-Aguirre A, Ladeia-Andrade S, Conn JE, Llanos-Cuentas A, Gamboa D, Rosanas-Urgell A, Vinetz JM. Relative contribution of low-density and asymptomatic infections to Plasmodium vivax transmission in the Amazon: pooled analysis of individual participant data from population-based cross-sectional surveys. LANCET REGIONAL HEALTH. AMERICAS 2022; 9:100169. [PMID: 35663000 PMCID: PMC9161731 DOI: 10.1016/j.lana.2021.100169] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Background Low-density and asymptomatic Plasmodium vivax infections remain largely undetected and untreated and may contribute significantly to malaria transmission in the Amazon. Methods We analysed individual participant data from population-based surveys that measured P vivax prevalence by microscopy and polymerase chain reaction (PCR) between 2002 and 2015 and modelled the relationship between parasite density and infectiousness to vectors using membrane feeding assay data. We estimated the proportion of sub-patent (i.e., missed by microscopy) and asymptomatic P vivax infections and examined how parasite density relates to clinical manifestations and mosquito infection in Amazonian settings. Findings We pooled 24,986 observations from six sites in Brazil and Peru. P vivax was detected in 6·8% and 2·1% of them by PCR and microscopy, respectively. 58·5% to 92·6% of P vivax infections were asymptomatic and 61·2% to 96·3% were sub-patent across study sites. P vivax density thresholds associated with clinical symptoms were one order of magnitude higher in children than in adults. We estimate that sub-patent parasite carriers are minimally infectious and contribute 12·7% to 24·9% of the community-wide P vivax transmission, while asymptomatic carriers are the source of 28·2% to 79·2% of mosquito infections. Interpretation Asymptomatic P vivax carriers constitute a vast infectious reservoir that, if targeted by malaria elimination strategies, could substantially reduce malaria transmission in the Amazon. Infected children may remain asymptomatic despite high parasite densities that elicit clinical manifestations in adults. Funding US National Institutes of Health, Fundação de Amparo à Pesquisa do Estado de São Paulo, and Belgium Development Cooperation.
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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,Corresponding author: Prof Marcelo U. Ferreira, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, 05508-900 São Paulo, SP, Brazil.
| | - Rodrigo M. Corder
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Igor C. Johansen
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | | | - Marta Moreno
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Angel Rosas-Aguirre
- Institute of Health and Society, Université catholique de Louvain, Brussels, Belgium
| | - Simone Ladeia-Andrade
- Laboratory of Parasitic Diseases, Oswaldo Cruz Institute, Fiocruz, Rio de Janeiro, Brazil
| | - Jan E. Conn
- Department of Biomedical Sciences, School of Public Health, University at Albany, State University of New York, Albany, NY, USA,Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Alejandro Llanos-Cuentas
- Instituto de Medicina Tropical "Alexander von Humboldt", Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Dionicia Gamboa
- Instituto de Medicina Tropical "Alexander von Humboldt", Universidad Peruana Cayetano Heredia, Lima, Peru,Laboratorio ICEMR-Amazonia, Laboratorios de Investigación y Desarrollo, Departamento de Ciencias Celulares y Moleculares, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Anna Rosanas-Urgell
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Joseph M. Vinetz
- Laboratorio ICEMR-Amazonia, Laboratorios de Investigación y Desarrollo, Departamento de Ciencias Celulares y Moleculares, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru,Section of Infectious Diseases, Department of Internal Medicine, Yale School of Medicine, New Haven, CT, USA
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9
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Ortiz DI, Piche-Ovares M, Romero-Vega LM, Wagman J, Troyo A. The Impact of Deforestation, Urbanization, and Changing Land Use Patterns on the Ecology of Mosquito and Tick-Borne Diseases in Central America. INSECTS 2021; 13:20. [PMID: 35055864 PMCID: PMC8781098 DOI: 10.3390/insects13010020] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/13/2021] [Accepted: 12/16/2021] [Indexed: 11/29/2022]
Abstract
Central America is a unique geographical region that connects North and South America, enclosed by the Caribbean Sea to the East, and the Pacific Ocean to the West. This region, encompassing Belize, Costa Rica, Guatemala, El Salvador, Honduras, Panama, and Nicaragua, is highly vulnerable to the emergence or resurgence of mosquito-borne and tick-borne diseases due to a combination of key ecological and socioeconomic determinants acting together, often in a synergistic fashion. Of particular interest are the effects of land use changes, such as deforestation-driven urbanization and forest degradation, on the incidence and prevalence of these diseases, which are not well understood. In recent years, parts of Central America have experienced social and economic improvements; however, the region still faces major challenges in developing effective strategies and significant investments in public health infrastructure to prevent and control these diseases. In this article, we review the current knowledge and potential impacts of deforestation, urbanization, and other land use changes on mosquito-borne and tick-borne disease transmission in Central America and how these anthropogenic drivers could affect the risk for disease emergence and resurgence in the region. These issues are addressed in the context of other interconnected environmental and social challenges.
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Affiliation(s)
- Diana I. Ortiz
- Biology Program, Westminster College, New Wilmington, PA 16172, USA
| | - Marta Piche-Ovares
- Laboratorio de Virología, Centro de Investigación en Enfermedades Tropicales (CIET), Universidad de Costa Rica, San José 11501, Costa Rica;
- Departamento de Virología, Escuela de Medicina Veterinaria, Universidad Nacional, Heredia 40104, Costa Rica
| | - Luis M. Romero-Vega
- Departamento de Patología, Escuela de Medicina Veterinaria, Universidad Nacional, Heredia 40104, Costa Rica;
- Laboratorio de Investigación en Vectores (LIVe), Centro de Investigación en Enfermedades Tropicales (CIET), Universidad de Costa Rica, San José 11501, Costa Rica;
| | - Joseph Wagman
- Malaria and Neglected Tropical Diseases Program, Center for Malaria Control and Elimination, PATH, Washington, DC 20001, USA;
| | - Adriana Troyo
- Laboratorio de Investigación en Vectores (LIVe), Centro de Investigación en Enfermedades Tropicales (CIET), Universidad de Costa Rica, San José 11501, Costa Rica;
- Departamento de Parasitología, Facultad de Microbiología, Universidad de Costa Rica, San José 11501, Costa Rica
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10
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Johansen IC, Rodrigues PT, Tonini J, Vinetz J, Castro MC, Ferreira MU. Cohort profile: the Mâncio Lima cohort study of urban malaria in Amazonian Brazil. BMJ Open 2021; 11:e048073. [PMID: 34789490 PMCID: PMC8727682 DOI: 10.1136/bmjopen-2020-048073] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 10/22/2021] [Indexed: 01/21/2023] Open
Abstract
PURPOSE This population-based open cohort study aims to investigate biological and sociodemographic drivers of malaria transmission in the main urban hotspot of Amazonian Brazil. PARTICIPANTS Nearly 20% of the households in the northwestern town of Mâncio Lima were randomly selected and 2690 participants were enrolled since April 2018. Sociodemographic, housing quality, occupational, behavioural and morbidity information and travel histories were collected during consecutive study visits. Blood samples from participants>3 months old were used for malaria diagnosis and human genetic studies; samples from participants with laboratory-confirmed malaria have been cryopreserved for genetic and phenotypic characterisation of parasites. Serology was introduced in 2020 to measure the prevalence and longevity of SARS-CoV-2 IgG antibodies. FINDINGS TO DATE Malaria prevalence rates were low (up to 1.0% for Plasmodium vivax and 0.6% for P. falciparum) during five consecutive cross-sectional surveys between April-May 2018 and October-November 2020; 63% of infections diagnosed by microscopy were asymptomatic. Malaria risk is heterogeneously distributed, with 20% study participants contributing 86% of the overall burden of P. vivax infection. Adult males are at greatest risk of infection and human mobility across the urban-rural interface may contribute to sustained malaria transmission. Local P. vivax parasites are genetically diverse and fragmented into discrete inbred lineages that remain stable across space and time. FUTURE PLANS Two follow-up visits, with similar study protocols, are planned in 2021. We aim to identify high-risk individuals that fuel onwards malaria transmission and represent a priority target for more intensive and effective control interventions. TRIAL REGISTRATION NUMBER NCT03689036.
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Affiliation(s)
| | | | - Juliana Tonini
- Parasitology, University of Sao Paulo, Sao Paulo, Brazil
| | - Joseph Vinetz
- Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Marcia C Castro
- Global Health and Population, Harvard School of Public Health, Boston, Massachusetts, USA
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11
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Costa GL, Mascarenhas MEP, Martin TOG, Fortini LG, Louzada J, Pereira DB, Aguiar ACC, Carvalho LH, de Brito CFA, Fontes CJF, de Sousa TN. A Comprehensive Analysis of the Genetic Diversity of Plasmodium falciparum Histidine-Rich Protein 2 (PfHRP2) in the Brazilian Amazon. Front Cell Infect Microbiol 2021; 11:742681. [PMID: 34621693 PMCID: PMC8491578 DOI: 10.3389/fcimb.2021.742681] [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: 07/16/2021] [Accepted: 08/19/2021] [Indexed: 11/16/2022] Open
Abstract
Early diagnosis and treatment are fundamental to the control and elimination of malaria. In many endemic areas, routine diagnosis is primarily performed microscopically, although rapid diagnostic tests (RDTs) provide a useful point-of-care tool. Most of the commercially available RDTs detect histidine-rich protein 2 (HRP2) of Plasmodium falciparum in the blood of infected individuals. Nonetheless, parasite isolates lacking the pfhrp2 gene are relatively frequent in some endemic regions, thereby hampering the diagnosis of malaria using HRP2-based RDTs. To track the efficacy of RDTs in areas of the Brazilian Amazon, we assessed pfhrp2 deletions in 132 P. falciparum samples collected from four malaria-endemic states in Brazil. Our findings show low to moderate levels of pfhrp2 deletion in different regions of the Brazilian Amazon. Overall, during the period covered by this study (2002-2020), we found that 10% of the P. falciparum isolates were characterized by a pfhrp2 deletion. Notably, however, the presence of pfhrp2-negative isolates has not been translated into a reduction in RDT efficacy, which in part may be explained by the presence of polyclonal infections. A further important finding was the discrepancy in the proportion of pfhrp2 deletions detected using two assessed protocols (conventional PCR versus nested PCR), which reinforces the need to perform a carefully planned laboratory workflow to assess gene deletion. This is the first study to perform a comprehensive analysis of PfHRP2 sequence diversity in Brazilian isolates of P. falciparum. We identified 10 PfHRP2 sequence patterns, which were found to be exclusive of each of the assessed regions. Despite the small number of PfHRP2 sequences available from South America, we found that the PfHRP2 sequences identified in Brazil and neighboring French Guiana show similar sequence patterns. Our findings highlight the importance of continuously monitoring the occurrence and spread of parasites with pfrhp2 deletions, while also taking into account the limitations of PCR-based testing methods associated with accuracy and the complexity of infections.
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Affiliation(s)
- Gabriel Luíz Costa
- Molecular Biology and Malaria Immunology Research Group, Instituto René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Brazil
| | - Maria Eduarda Pereira Mascarenhas
- Molecular Biology and Malaria Immunology Research Group, Instituto René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Brazil
| | | | - Laura Guimarães Fortini
- Molecular Biology and Malaria Immunology Research Group, Instituto René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Brazil
| | | | | | | | - Luzia Helena Carvalho
- Molecular Biology and Malaria Immunology Research Group, Instituto René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Brazil
| | - Cristiana Ferreira Alves de Brito
- Molecular Biology and Malaria Immunology Research Group, Instituto René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Brazil
| | | | - Tais Nóbrega de Sousa
- Molecular Biology and Malaria Immunology Research Group, Instituto René Rachou, Fundação Oswaldo Cruz (FIOCRUZ), Belo Horizonte, Brazil
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12
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Ueno TMRL, Lima LNGC, Sardinha DM, Rodrigues YC, de Souza HUS, Teixeira PR, Guimarães RJDPSE, Lima KVB, Ventura AMRDS. Socio-Epidemiological Features and Spatial Distribution of Malaria in an Area under Mining Activity in the Brazilian Amazon Region. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph181910384. [PMID: 34639684 PMCID: PMC8507758 DOI: 10.3390/ijerph181910384] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 08/20/2021] [Accepted: 09/16/2021] [Indexed: 11/16/2022]
Abstract
Malaria is an acute febrile infectious disease that represents an important public health problem in the Brazilian amazon region. The present study described the socio-epidemiological and spatial characteristics of malaria in a population from the Tapajós mining areas, Pará, Brazilian Amazon. A cross-sectional study, including individuals from Itaituba city, an area under mining activity influence, was conducted. The geographic coordinates were obtained in the field using the Global Positioning System (GPS) Garmin 78csx; for spatial analysis, we used the Kernel Density Estimator with the application of scanning statistics with the SaTScan software. Of the 908 individuals, 311 were positive for malaria. Most of the malaria cases were associated with male individuals, gold miners and with a monthly income of 4-6 salaries. Binary logistic regression analysis demonstrated that gold miners were nearly five times more likely to acquire malaria. In addition, a context of risk for sexually transmitted infections, substance abuse and poor support conditions was observed, worsening the healthcare scenario in this endemic area for malaria. The spatial distribution of malaria cases is irregular in the municipality with hotspot areas located in the Amana Flona that coincide with areas of illegal mining and high human mobility. Finally, the presented socio-epidemiological and spatial distribution data may aid in the development of more effective control measures for malaria in the area.
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Affiliation(s)
- Thalyta Mariany Rêgo Lopes Ueno
- Programa de Pós-Graduação em Biologia Parasitária na Amazônia (PPGBPA), Instituto Evandro Chagas (IEC), Universidade do Estado do Pará (UEPA), Belém 66087-662, Brazil; (L.N.G.C.L.); (Y.C.R.); (K.V.B.L.); (A.M.R.d.S.V.)
- Correspondence: ; Tel.: +55-91-98252-7226
| | - Luana Nepomuceno Gondim Costa Lima
- Programa de Pós-Graduação em Biologia Parasitária na Amazônia (PPGBPA), Instituto Evandro Chagas (IEC), Universidade do Estado do Pará (UEPA), Belém 66087-662, Brazil; (L.N.G.C.L.); (Y.C.R.); (K.V.B.L.); (A.M.R.d.S.V.)
- Seção de Bacteriologia e Micologia (SABMI), Instituto Evandro Chagas (IEC), Ananindeua 67030-000, Brazil;
- Programa de Pós-Graduação em Epidemiologia e Vigilância em Saúde (PPGEVS), Instituto Evandro Chagas (IEC), Ananindeua 67030-000, Brazil;
| | - Daniele Melo Sardinha
- Seção de Bacteriologia e Micologia (SABMI), Instituto Evandro Chagas (IEC), Ananindeua 67030-000, Brazil;
- Programa de Pós-Graduação em Epidemiologia e Vigilância em Saúde (PPGEVS), Instituto Evandro Chagas (IEC), Ananindeua 67030-000, Brazil;
| | - Yan Corrêa Rodrigues
- Programa de Pós-Graduação em Biologia Parasitária na Amazônia (PPGBPA), Instituto Evandro Chagas (IEC), Universidade do Estado do Pará (UEPA), Belém 66087-662, Brazil; (L.N.G.C.L.); (Y.C.R.); (K.V.B.L.); (A.M.R.d.S.V.)
- Seção de Bacteriologia e Micologia (SABMI), Instituto Evandro Chagas (IEC), Ananindeua 67030-000, Brazil;
| | - Herberto Ueno Seelig de Souza
- Programa de Pós-Graduação em Ciências Florestais (PPGCF), Universidade Federal Rural da Amazônia (UFRA), Belém 66077-830, Brazil;
| | - Paula Ribeiro Teixeira
- Discente do Curso de Licenciatura em Ciências Biológicas, Instituto de Educação, Ciência e Tecnologia do, Pará (IFPA), Itaituba 68183-300, Brazil;
| | - Ricardo José de Paula Souza e Guimarães
- Programa de Pós-Graduação em Epidemiologia e Vigilância em Saúde (PPGEVS), Instituto Evandro Chagas (IEC), Ananindeua 67030-000, Brazil;
- Laboratório de Geoprocessamento (LABGEO), Instituto Evandro Chagas (IEC), Ananindeua 67030-000, Brazil
| | - Karla Valéria Batista Lima
- Programa de Pós-Graduação em Biologia Parasitária na Amazônia (PPGBPA), Instituto Evandro Chagas (IEC), Universidade do Estado do Pará (UEPA), Belém 66087-662, Brazil; (L.N.G.C.L.); (Y.C.R.); (K.V.B.L.); (A.M.R.d.S.V.)
- Seção de Bacteriologia e Micologia (SABMI), Instituto Evandro Chagas (IEC), Ananindeua 67030-000, Brazil;
| | - Ana Maria Revorêdo da Silva Ventura
- Programa de Pós-Graduação em Biologia Parasitária na Amazônia (PPGBPA), Instituto Evandro Chagas (IEC), Universidade do Estado do Pará (UEPA), Belém 66087-662, Brazil; (L.N.G.C.L.); (Y.C.R.); (K.V.B.L.); (A.M.R.d.S.V.)
- Seção de Parasitologia (SAPAR), Instituto Evandro Chagas (IEC), Ananindeua 67030-000, Brazil
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13
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Fontoura PS, Silva MF, da Costa AS, Ribeiro FS, Ferreira MS, Ladeia-Andrade S, Tonini J, Rodrigues PT, Castro MC, Ferreira MU. Monthly biological larviciding associated with a tenfold decrease in larval density in fish farming ponds and reduced community-wide malaria incidence in northwestern Brazil. Parasit Vectors 2021; 14:445. [PMID: 34479606 PMCID: PMC8414731 DOI: 10.1186/s13071-021-04964-3] [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: 07/08/2021] [Accepted: 08/17/2021] [Indexed: 12/01/2022] Open
Abstract
Background Larvicides are typically applied to fixed and findable mosquito breeding sites, such as fish farming ponds used in commercial aquaculture, to kill immature forms and thereby reduce the size of adult malaria vector populations. However, there is little evidence suggesting that larviciding may suppress community-wide malaria transmission outside Africa. Here, we tested whether the biological larvicide VectoMax FG applied at monthly intervals to fish farming ponds can reduce malaria incidence in Amazonian Brazil. Methods This study was carried out in Vila Assis Brasil (VAB; population 1700), a peri-urban malaria hotspot in northwestern Brazil with a baseline annual parasite incidence of 553 malaria cases per 1000 inhabitants. The intervention consisted of monthly treatments with 20 kg/ha of VectoMax FG of all water-filled fish ponds in VAB (n ranging between 167 and 170) with a surface area between 20 and 8000 m2, using knapsack power mistblowers. We used single-group interrupted time-series analysis to compare monthly larval density measurements in fish ponds during a 14-month pre-intervention period (September 2017–October 2018), with measurements made during November 2018–October 2019 and shortly after the 12-month intervention (November 2019). We used interrupted time-series analysis with a comparison group to contrast the malaria incidence trends in VAB and nearby nonintervention localities before and during the intervention. Results Average larval densities decreased tenfold in treated fish farming ponds, from 0.467 (95% confidence interval [CI], 0.444–0.490) anopheline larvae per dip pre-intervention (September 2017–October 2018) to 0.046 (95% CI, 0.041–0.051) larvae per dip during (November 2018–October 2019) and shortly after the intervention (November 2019). Average malaria incidence rates decreased by 0.08 (95% CI, 0.04–0.11) cases per 100 person-months (P < 0.0001) during the intervention in VAB and remained nearly unchanged in comparison localities. We estimate that the intervention averted 24.5 (95% CI, 6.2–42.8) malaria cases in VAB between January and December 2019. Conclusions Regular larviciding is associated with a dramatic decrease in larval density and a modest but significant decrease in community-wide malaria incidence. Larviciding may provide a valuable complementary vector control strategy in commercial aquaculture settings across the Amazon. Graphical abstract ![]()
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Affiliation(s)
- Pablo S Fontoura
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, São Paulo, SP, 05508-900, Brazil
| | - Marcos F Silva
- Multidisciplinary Center, Federal University of Acre, Cruzeiro do Sul, Brazil
| | - Anderson S da Costa
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, São Paulo, SP, 05508-900, Brazil
| | - Francismar S Ribeiro
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, São Paulo, SP, 05508-900, Brazil
| | - Marcílio S Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, São Paulo, SP, 05508-900, Brazil
| | - Simone Ladeia-Andrade
- Laboratory of Parasitic Diseases, Oswaldo Cruz Institute, Fiocruz, Rio de Janeiro, RJ, 21045-900, Brazil
| | - Juliana Tonini
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, São Paulo, SP, 05508-900, Brazil
| | - Priscila T Rodrigues
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, São Paulo, SP, 05508-900, Brazil
| | - Marcia C Castro
- Department of Global Health and Population, Harvard T. H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Marcelo U Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, São Paulo, SP, 05508-900, Brazil.
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14
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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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15
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Arévalo-Herrera M, Miura K, Cespedes N, Echeverry C, Solano E, Castellanos A, Ramirez JS, Miranda A, Kajava AV, Long C, Corradin G, Herrera S. Immunoreactivity of Sera From Low to Moderate Malaria-Endemic Areas Against Plasmodium vivax r Pvs48/45 Proteins Produced in Escherichia coli and Chinese Hamster Ovary Systems. Front Immunol 2021; 12:634738. [PMID: 34248932 PMCID: PMC8264144 DOI: 10.3389/fimmu.2021.634738] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Accepted: 05/25/2021] [Indexed: 11/13/2022] Open
Abstract
P48/45 is a conserved gametocyte antigen involved in Plasmodium parasite fertilization. A recombinant Plasmodium vivax P48/45 (Pvs48/45) protein expressed in Escherichia coli (E. coli) was highly antigenic and immunogenic in experimental animals and elicited specific transmission-blocking (TB) antibodies in a previous pilot study. Here, a similar Pvs48/45 gene was expressed in Chinese Hamster Ovary (CHO) cells and we compared its immunoreactivity with the E. coli product. Specific antibody titers were determined using plasma from Colombian individuals (n=227) living in endemic areas where both P. vivax and P. falciparum are prevalent and from Guatemala (n=54) where P. vivax is highly prevalent. In Colombia, plasma seroprevalence to CHO-rPvs48/45 protein was 46.3%, while for E. coli-rPvs48/45 protein was 36.1% (p<0.001). In Guatemala, the sero prevalence was 24.1% and 14.8% (p<0.001), respectively. Reactivity index (RI) against both proteins showed an age-dependent increase. IgG2 was the predominant subclass and the antibody avidity index evaluated by ELISA ranged between 4-6 mol/L. Ex vivo P. vivax mosquito direct membrane feeding assays (DMFA) performed in presence of study plasmas, displayed significant parasite transmission-blocking (TB), however, there was no direct correlation between antibody titers and oocysts transmission reduction activity (%TRA). Nevertheless, DMFA with CHO rPvs48/45 affinity purified IgG showed a dose response; 90.2% TRA at 100 μg/mL and 71.8% inhibition at 10 μg/mL. In conclusion, the CHO-rPvs48/45 protein was more immunoreactive in most of the malaria endemic places studied, and CHO-rPvs48/45 specific IgG showed functional activity, supporting further testing of the protein vaccine potential.
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Affiliation(s)
- Myriam Arévalo-Herrera
- Immunology Department, Malaria Vaccine and Drug Development Center, Cali, Colombia
- Immunology Department, Caucaseco Scientific Research Center, Cali, Colombia
| | - Kazutoyo Miura
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, United States
| | - Nora Cespedes
- Immunology Department, Malaria Vaccine and Drug Development Center, Cali, Colombia
| | - Carlos Echeverry
- Immunology Department, Malaria Vaccine and Drug Development Center, Cali, Colombia
| | - Eduardo Solano
- Immunology Department, Caucaseco Scientific Research Center, Cali, Colombia
| | - Angélica Castellanos
- Immunology Department, Malaria Vaccine and Drug Development Center, Cali, Colombia
| | | | - Adolfo Miranda
- Parasitology Department, Centro Nacional de Epidemiología (CNE), Guatemala City, Guatemala
| | - Andrey V. Kajava
- Centre de Recherche en Biologie Cellulaire de Montpellier, Université Montpellier, Montpellier, France
| | - Carole Long
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, United States
| | | | - Sócrates Herrera
- Immunology Department, Malaria Vaccine and Drug Development Center, Cali, Colombia
- Immunology Department, Caucaseco Scientific Research Center, Cali, Colombia
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Fouque F, Knox T. Special Programme for Research and Training in Tropical Diseases-coordinated Multicountry Study to Determine the Burden and Causes of Residual Malaria Across Different Regions. J Infect Dis 2021; 223:S91-S98. [PMID: 33906219 PMCID: PMC8079130 DOI: 10.1093/infdis/jiaa605] [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] [Indexed: 11/14/2022] Open
Abstract
The burden and causes of residual malaria were investigated between 2015 and 2019 through 5 research projects coordinated by the Special Program for Research and Training in Tropical Diseases (TDR), cosponsored by the United Nations Development Programme, UNICEF, the World Bank, the World Health Organization (WHO) and the WHO Global Malaria Programme. The 5 projects included 10 countries in 4 WHO regions: Africa, the Americas, South-East Asia, and the Western Pacific. The countries represented a range of malaria endemicities, from low to high levels of transmission. The main findings of the projects indicate that overall the core malaria vector control tools (long-lasting insecticidal nets [LLIN] and indoor residual spraying) were not deployed in the optimal way and/or not efficient in many settings of the supported projects. Furthermore, vector biting behavior and human activity-associated factors strongly contributed to malaria persistence. Changes in vector species composition and abundance, with an increase in outdoor biting, were also reported. Some of these factors may be an adaptation of the vectors to the deployment of the tools and/or can be linked to other sectors, such as agricultural practices, environmental changes, social factors, and water management. Human behaviors and sleeping habits that included activities and sleeping outside villages in unprotected dwellings were another part of the problem. The evidence collated demonstrates the need for new approaches, such as the multisectoral one and new vector control tools, all adapted to the local contexts and integrated into current malaria programs.
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Affiliation(s)
- Florence Fouque
- Research for Implementation Unit, Special Programme for Research and Training in Tropical Diseases, Geneva, Switzerland
| | - Tessa Knox
- World Health Organization, Port Vila, Vanuatu
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17
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de Oliveira TC, Rodrigues PT, Early AM, Duarte AMRC, Buery JC, Bueno MG, Catão-Dias JL, Cerutti C, Rona LDP, Neafsey DE, Ferreira MU. Plasmodium simium: population genomics reveals the origin of a reverse zoonosis. J Infect Dis 2021; 224:1950-1961. [PMID: 33870436 DOI: 10.1093/infdis/jiab214] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 04/14/2021] [Indexed: 11/12/2022] Open
Abstract
The population history of Plasmodium simium, which causes malaria in sylvatic Neotropical monkeys and humans along the Atlantic Coast of Brazil, remains disputed. Genetically diverse P. vivax populations from various sources, including the lineages that founded the species P. simium, are thought to have arrived in the Americas in separate migratory waves. However, here we find a minimal genome-level differentiation between P. simium and present-day New World P. vivax isolates, consistent with their common geographic origin and subsequent divergence on this continent. The meagre genetic diversity in P. simium samples from humans and monkeys implies a recent transfer from humans to non-human primates - a unique example of malaria as a reverse zoonosis of public health significance. Likely genomic signatures of P. simium adaptation to new hosts include the deletion of >40% of a key erythrocyte invasion ligand, PvRBP2a, which may have favored more efficient simian host cell infection.
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Affiliation(s)
- Thaís C de Oliveira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Priscila T Rodrigues
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Angela M Early
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA, USA.,Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - Ana Maria R C Duarte
- Laboratory of Biochemistry and Molecular Biology, Superintendency for the Control of Endemics (SUCEN), State Secretary of Health, São Paulo, Brazil.,Laboratory of Protozoology, Institute of Tropical Medicine of São Paulo, University of São Paulo, São Paulo, Brazil
| | - Julyana C Buery
- Department of Social Medicine, Center for Health Sciences, Federal University of Espírito Santo, Vitória, Brazil
| | - Marina G Bueno
- Laboratory of Wildlife Comparative Pathology, Department of Pathology, School of Veterinary Medicine and Animal Sciences, University of São Paulo, São Paulo, Brazil.,Laboratory of Comparative and Environmental Virology, Oswaldo Cruz Institute, Fiocruz, Rio de Janeiro, Brazil
| | - José L Catão-Dias
- Laboratory of Wildlife Comparative Pathology, Department of Pathology, School of Veterinary Medicine and Animal Sciences, University of São Paulo, São Paulo, Brazil
| | - Crispim Cerutti
- Department of Social Medicine, Center for Health Sciences, Federal University of Espírito Santo, Vitória, Brazil
| | - Luísa D P Rona
- Department of Cell Biology, Embryology, and Genetics, Federal University of Santa Catarina, Florianópolis, Brazil.,National Council for Scientific and Technological Development, National Institute of Science and Technology in Molecular Entomology, Rio de Janeiro, Brazil
| | - Daniel E Neafsey
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA, USA.,Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - Marcelo U Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
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18
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Abstract
BACKGROUND Cross-border malaria is a major barrier to elimination efforts. Along the Venezuela-Brazil-Guyana border, intense human mobility fueled primarily by a humanitarian crisis and illegal gold mining activities has increased the occurrence of cross-border cases in Brazil. Roraima, a Brazilian state situated between Venezuela and Guyana, bears the greatest burden. This study analyses the current cross-border malaria epidemiology in Northern Brazil between the years 2007 and 2018. METHODS De-identified data on reported malaria cases in Brazil were obtained from the Malaria Epidemiological Surveillance Information System for the years 2007 to 2018. Pearson's Chi-Square test of differences was utilized to assess differences between characteristics of cross-border cases originating from Venezuela and Guyana, and between border and transnational cases. A logistic regression model was used to predict imported status of cases. RESULTS Cross-border cases from Venezuela and Guyana made up the majority of border and transnational cases since 2012, and Roraima remained the largest receiving state for cross-border cases over this period. There were significant differences in the profiles of border and transnational cases originating from Venezuela and Guyana, including type of movement and nationality of patients. Logistic regression results demonstrated Venezuelan and Guyanese nationals, Brazilian miners, males, and individuals of working age had heightened odds of being an imported case. Furthermore, Venezuelan citizens had heightened odds of seeking care in municipalities adjacent Venezuela, rather than transnational municipalities. CONCLUSIONS Cross-border malaria contributes to the malaria burden at the Venezuela-Guyana-Brazil border. The identification of distinct profiles of case importation provides evidence on the need to strengthen surveillance at border areas, and to deploy tailored strategies that recognize different mobility routes, such as the movement of refuge-seeking individuals and of Brazilians working in mining.
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Affiliation(s)
- Nicholas J Arisco
- Department of Global Health and Population, Harvard T.H. Chan School of Public Health, 655 Huntington Avenue, Building 1, Room 1002A, Boston, MA, 02115, USA
| | - Cassio Peterka
- Diretoria de Vigilancia Epidemiológica, Secretaria de Estado de Saúde Do DF, Brasília, DF, 70390-125, Brazil
| | - Marcia C Castro
- Department of Global Health and Population, Harvard T.H. Chan School of Public Health, 655 Huntington Avenue, Building 1, Room 1002A, Boston, MA, 02115, USA.
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19
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Johansen IC, Rodrigues PT, Ferreira MU. Human mobility and urban malaria risk in the main transmission hotspot of Amazonian Brazil. PLoS One 2020; 15:e0242357. [PMID: 33237945 PMCID: PMC7688137 DOI: 10.1371/journal.pone.0242357] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 10/30/2020] [Indexed: 11/22/2022] Open
Abstract
Malaria in the Amazon is often perceived as an exclusively rural disease, but transmission has been increasingly documented within and near urban centers. Here we explore patterns and causes of urban-to-rural mobility, which places travelers at risk of malaria in Mâncio Lima, the main malaria hotspot in northwestern Brazil. We also analyze rural-to-urban mobility caused by malaria treatment seeking, which poses an additional risk of infection to urban residents. We show that the rural localities most frequently visited by urban residents–typically farming settlements in the vicinity of the town–are those with the most intense malaria transmission and also the most frequent source localities of imported malaria cases diagnosed in the town. The most mobile urban residents are typically poor males 16 to 60-years old from multi-sited households who lack a formal job. Highly mobile residents represent a priority target for more intensive and effective malaria control interventions, that cannot be readily delivered to the entire community, in this and similar urbanized endemic settings across the Amazon.
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Affiliation(s)
- Igor C. Johansen
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo (SP), Brazil
- * E-mail: (ICJ); (MUF)
| | - Priscila T. Rodrigues
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo (SP), Brazil
| | - Marcelo U. Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo (SP), Brazil
- * E-mail: (ICJ); (MUF)
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20
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Massad E, Laporta GZ, Conn JE, Chaves LS, Bergo ES, Figueira EAG, Bezerra Coutinho FA, Lopez LF, Struchiner C, Sallum MAM. The risk of malaria infection for travelers visiting the Brazilian Amazonian region: A mathematical modeling approach. Travel Med Infect Dis 2020; 37:101792. [PMID: 32771653 DOI: 10.1016/j.tmaid.2020.101792] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 05/30/2020] [Accepted: 06/15/2020] [Indexed: 12/15/2022]
Abstract
BACKGROUND Human mobility between malaria endemic and malaria-free areas can hinder control and elimination efforts in the Amazon basin, maintaining Plasmodium circulation and introduction to new areas. METHODS The analysis begins by estimating the incidence of malaria in areas of interest. Then, the risk of infection as a function of the duration of stay after t0 was calculated as the number of infected travelers over the number of arrived travelers. Differential equations were employed to estimate the risk of nonimmune travelers acquiring malaria in Amazonian municipalities. Risk was calculated as a result of the force of the infection in terms of local dynamics per time of arrival and duration of visit. RESULTS Maximum risk occurred at the peak or at the end of the rainy season and it was nonlinearly (exponentially) correlated with the fraction of infected mosquitoes. Relationship between the risk of malaria and duration of visit was linear and positively correlated. Relationship between the risk of malaria and the time of arrival in the municipality was dependent on local effects of seasonality. CONCLUSIONS The risk of nonimmune travelers acquiring malaria is not negligible and can maintain regional circulation of parasites, propagating introductions in areas where malaria has been eliminated.
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Affiliation(s)
- Eduardo Massad
- Escola de Matemática Aplicada, Fundação Getúlio Vargas, Rio de Janeiro, Brazil
| | - Gabriel Zorello Laporta
- Setor de Pós-graduação, Pesquisa e Inovação, Centro Universitário Saúde ABC, Fundação do ABC, Santo André, SP, Brazil
| | - Jan Evelyn Conn
- Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Leonardo Suveges Chaves
- Departamento de Epidemiologia, Faculdade de Saúde Pública, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Eduardo Sterlino Bergo
- Superintendência de Controle de Endemias, Secretaria de Estado da Saúde de São Paulo, Araraquara, SP, Brazil
| | | | | | | | - Claudio Struchiner
- Escola de Matemática Aplicada, Fundação Getúlio Vargas, Rio de Janeiro, Brazil
| | - Maria Anice Mureb Sallum
- Departamento de Epidemiologia, Faculdade de Saúde Pública, Universidade de São Paulo, São Paulo, SP, Brazil.
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21
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Corder RM, de Lima ACP, Khoury DS, Docken SS, Davenport MP, Ferreira MU. Quantifying and preventing Plasmodium vivax recurrences in primaquine-untreated pregnant women: An observational and modeling study in Brazil. PLoS Negl Trop Dis 2020; 14:e0008526. [PMID: 32735631 PMCID: PMC7423143 DOI: 10.1371/journal.pntd.0008526] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 08/12/2020] [Accepted: 06/26/2020] [Indexed: 12/27/2022] Open
Abstract
Each year, 4.3 million pregnant women are exposed to malaria risk in Latin America and the Caribbean. Plasmodium vivax causes 76% of the regional malaria burden and appears to be less affected than P. falciparum by current elimination efforts. This is in part due to the parasite's ability to stay dormant in the liver and originate relapses within months after a single mosquito inoculation. Primaquine (PQ) is routinely combined with chloroquine (CQ) or other schizontocidal drugs to supress P. vivax relapses and reduce the risk of late blood-stage recrudescences of parasites with low-grade CQ resistance. However, PQ is contraindicated for pregnant women, who remain at increased risk of repeated infections following CQ-only treatment. Here we apply a mathematical model to time-to-recurrence data from Juruá Valley, Brazil's main malaria transmission hotspot, to quantify the extra burden of parasite recurrences attributable to PQ ineligibility in pregnant women. The model accounts for competing risks, since relapses and late recrudescences (that may be at least partially prevented by PQ) and new infections (that are not affected by PQ use) all contribute to recurrences. We compare recurrence rates observed after primary P. vivax infections in 158 pregnant women treated with CQ only and 316 P. vivax infections in non-pregnant control women, matched for age, date of infection, and place of residence, who were administered a standard CQ-PQ combination. We estimate that, once infected with P. vivax, 23% of the pregnant women have one or more vivax malaria recurrences over the next 12 weeks; 86% of these early P. vivax recurrences are attributable to relapses or late recrudescences, rather than new infections that could be prevented by reducing malaria exposure during pregnancy. Model simulations indicate that weekly CQ chemoprophylaxis extending over 4 to 12 weeks, starting after the first vivax malaria episode diagnosed in pregnancy, might reduce the risk of P. vivax recurrences over the next 12 months by 20% to 65%. We conclude that post-treatment CQ prophylaxis could be further explored as a measure to prevent vivax malaria recurrences in pregnancy and avert their adverse effects on maternal and neonatal health.
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Affiliation(s)
- Rodrigo M. Corder
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- * E-mail: (RMC); (MUF)
| | - Antonio C. P. de Lima
- Department of Statistics, Institute of Mathematics and Statistics, University of São Paulo, São Paulo, Brazil
| | - David S. Khoury
- Kirby Institute for Infection and Immunity, University of New South Wales, Sidney, Australia
| | - Steffen S. Docken
- Kirby Institute for Infection and Immunity, University of New South Wales, Sidney, Australia
| | - Miles P. Davenport
- Kirby Institute for Infection and Immunity, University of New South Wales, Sidney, Australia
| | - Marcelo U. Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- * E-mail: (RMC); (MUF)
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22
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Corder RM, Ferreira MU, Gomes MGM. Modelling the epidemiology of residual Plasmodium vivax malaria in a heterogeneous host population: A case study in the Amazon Basin. PLoS Comput Biol 2020; 16:e1007377. [PMID: 32168349 PMCID: PMC7108741 DOI: 10.1371/journal.pcbi.1007377] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 03/31/2020] [Accepted: 01/29/2020] [Indexed: 02/07/2023] Open
Abstract
The overall malaria burden in the Americas has decreased dramatically over the past two decades, but residual transmission pockets persist across the Amazon Basin, where Plasmodium vivax is the predominant infecting species. Current elimination efforts require a better quantitative understanding of malaria transmission dynamics for planning, monitoring, and evaluating interventions at the community level. This can be achieved with mathematical models that properly account for risk heterogeneity in communities approaching elimination, where few individuals disproportionately contribute to overall malaria prevalence, morbidity, and onwards transmission. Here we analyse demographic information combined with routinely collected malaria morbidity data from the town of Mâncio Lima, the main urban transmission hotspot of Brazil. We estimate the proportion of high-risk subjects in the host population by fitting compartmental susceptible-infected-susceptible (SIS) transmission models simultaneously to age-stratified vivax malaria incidence densities and the frequency distribution of P. vivax malaria attacks experienced by each individual over 12 months. Simulations with the best-fitting SIS model indicate that 20% of the hosts contribute 86% of the overall vivax malaria burden. Despite the low overall force of infection typically found in the Amazon, about one order of magnitude lower than that in rural Africa, high-risk individuals gradually develop clinical immunity following repeated infections and eventually constitute a substantial infectious reservoir comprised of asymptomatic parasite carriers that is overlooked by routine surveillance but likely fuels onwards malaria transmission. High-risk individuals therefore represent a priority target for more intensive and effective interventions that may not be readily delivered to the entire community.
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Affiliation(s)
- Rodrigo M. Corder
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- * E-mail: (RMC); (MGMG)
| | - Marcelo U. Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - M. Gabriela M. Gomes
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
- CIBIO-InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, and CMUP, Centro de Matemática da Universidade do Porto, Porto, Portugal
- * E-mail: (RMC); (MGMG)
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