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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Epidemiology of Disappearing Plasmodium vivax Malaria: A Case Study in Rural Amazonia

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Barbosa, Susana [1] ; Gozze, Amanda B. [1] ; Lima, Nathalia F. [1] ; Batista, Camilla L. [1] ; Bastos, Melissa da Silva [1] ; Nicolete, Vanessa C. [1] ; Fontoura, Pablo S. [1] ; Goncalves, Raquel M. [1] ; Viana, Susana Ariane S. [1] ; Menezes, Maria Jose [1] ; Scopel, Kezia Katiani G. [2] ; Cavasini, Carlos E. [3] ; Malafronte, Rosely dos Santos [4] ; da Silva-Nunes, Monica [5] ; Vinetz, Joseph M. [6, 7, 8] ; Castro, Marcia C. [9] ; Ferreira, Marcelo U. [1]
Total Authors: 17
[1] Univ Sao Paulo, Inst Biomed Sci, Dept Parasitol, Sao Paulo - Brazil
[2] Univ Fed Juiz de Fora, Inst Biol Sci, Dept Parasitol Microbiol & Immunol, Juiz De Fora, MG - Brazil
[3] Fac Med Sao Jose do Rio Preto, Dept Dermatol Infect & Parasit Dis, Sao Paulo - Brazil
[4] Univ Sao Paulo, Inst Trop Med Sao Paulo, Sao Paulo - Brazil
[5] Univ Fed Acre, Ctr Hlth Sci & Sports, Rio Branco, Acre - Brazil
[6] Univ Calif San Diego, Dept Med, Div Infect Dis, La Jolla, CA 92093 - USA
[7] Univ Peruana Cayetano Heredia, Res & Dev Lab, Alexander von Humboldt Inst Trop Med, Lima - Peru
[8] Univ Peruana Cayetano Heredia, Res & Dev Lab, Dept Cellular & Mol Sci, Fac Sci, Lima - Peru
[9] Harvard Univ, Sch Publ Hlth, Dept Global Hlth & Populat, Boston, MA 02115 - USA
Total Affiliations: 9
Document type: Journal article
Source: PLoS Neglected Tropical Diseases; v. 8, n. 8 AUG 2014.
Web of Science Citations: 55

Background: New frontier settlements across the Amazon Basin pose a major challenge for malaria elimination in Brazil. Here we describe the epidemiology of malaria during the early phases of occupation of farming settlements in Remansinho area, Brazilian Amazonia. We examine the relative contribution of low-density and asymptomatic parasitemias to the overall Plasmodium vivax burden over a period of declining transmission and discuss potential hurdles for malaria elimination in Remansinho and similar settings. Methods: Eight community-wide cross-sectional surveys, involving 584 subjects, were carried out in Remansinho over 3 years and complemented by active and passive surveillance of febrile illnesses between the surveys. We used quantitative PCR to detect low-density asexual parasitemias and gametocytemias missed by conventional microscopy. Mixed-effects multiple logistic regression models were used to characterize independent risk factors for P. vivax infection and disease. Principal Findings/Conclusions: P. vivax prevalence decreased from 23.8% (March-April 2010) to 3.0% (April-May 2013), with no P. falciparum infections diagnosed after March-April 2011. Although migrants from malaria-free areas were at increased risk of malaria, their odds of having P. vivax infection and disease decreased by 2-3% with each year of residence in Amazonia. Several findings indicate that low-density and asymptomatic P. vivax parasitemias may complicate residual malaria elimination in Remansinho: (a) the proportion of subpatent infections (i. e. missed by microscopy) increased from 43.8% to 73.1% as P. vivax transmission declined; (b) most (56.6%) P. vivax infections were asymptomatic and 32.8% of them were both subpatent and asymptomatic; (c) asymptomatic parasite carriers accounted for 54.4% of the total P. vivax biomass in the host population; (d) over 90% subpatent and asymptomatic P. vivax had PCR-detectable gametocytemias; and (e) few (17.0%) asymptomatic and subpatent P. vivax infections that were left untreated progressed to clinical disease over 6 weeks of follow-up and became detectable by routine malaria surveillance. (AU)

FAPESP's process: 09/52729-9 - Determinants and consequences of asymptomatic carriage of malaria parasites: population-based studies in rural Brazilian Amazonia
Grantee:Marcelo Urbano Ferreira
Support Opportunities: Regular Research Grants
FAPESP's process: 13/23770-6 - Optimising malaria case detection in a low transmission setting in rural Brazilian Amazon
Grantee:Susana Do Carmo Pinto Barbosa
Support Opportunities: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 13/17259-7 - Geospatial methods for investigating Plasmodium vivax reservoirs in rural Brazilian Amazon
Grantee:Marcelo Urbano Ferreira
Support Opportunities: Research Grants - Visiting Researcher Grant - International
FAPESP's process: 09/12180-8 - Determinants and consequences of asymptomatic carriage of malaria parasites: population-based survey in rural Brazilian Amazonia
Grantee:Amanda Begosso Gozze
Support Opportunities: Scholarships in Brazil - Master