| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Five community-based cross-sectional surveys of malaria morbidity and associated risk factors in remote riverine populations in northwestern Brazil showed average parasite rates of 4.2% (thick-smear microscopy) and 14.4% (polymerase chain reaction [PCR]) in the overall population, with a spleen rate of 13.9% among children 2–9 years of age. Plasmodium vivax was 2.8 times more prevalent than P. falciparum, with rare instances of P. malariae and mixed-species infections confirmed by PCR; 9.6% of asymptomatic subjects had parasitemias detected by PCR. Low-grade parasitemia detected by PCR only was a risk factor for anemia, after controlling for age and other covariates. Although clinical and subclinical infections occurred in all age groups, the risk of infection and disease decreased significantly with increasing age, after adjustment for several covariates in multilevel logistic regression models. These findings suggest that the continuous exposure to hypo- or mesoendemic malaria may induce significant anti-parasite and anti-disease immunity in native Amazonians.
Received April 16, 2008. Accepted for publication November 22, 2008.
Acknowledgments: The authors thank the inhabitants of Jaú National Park for enthusiastic participation in the study; Vitória Amazônica Foundation (FVA) and Brazilian Institute of the Environment and Natural Resources (IBAMA) for granting access of the research team to Jaú National Park; the Health Department of Barcelos and the malaria control teams of Barcelos and Novo Airão for help with fieldwork; Deise L. Oliveira, Patrícia P. Martins, Laura C. Santos, Patricia C. Escobar (Fiocruz), and Rosely S. Malafronte, Mayra N. Nassar and Adriana Y. Maeda (Institute of Tropical Medicine of São Paulo) for help with PCR-based malaria diagnosis; Débora Bergara, Bianca F. Pereira, and Gisele J. Ferreira (Superintendency for the Control of Endemies) for help with serological analysis; Cassiano P. Nunes (University of São Paulo) for artwork; Francisco das Chagas O. Luz (Ministry of Health of Brazil, Brasília) for reviewing all malaria slides; and Ângela C. V. Junqueira, Alessandra Q. Gonçalves, Pedro A. Viñas, Júlio C. Miguel, and Márcio N. Bóia (Fiocruz) for overall support.
Financial support: This study was funded by PAPES IV/Fiocruz and CNPq (410398/2006-3) (JRC) and the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, 05/51988-0) (MUF). SL-A received a doctoral scholarship and now receives a postdoctoral scholarship, both from the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); MUF and JRC are research fellows of the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brazil.
* Address correspondence to Marcelo Urbano Ferreira, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, 05508-900 São Paulo (SP), Brazil. E-mail: muferrei{at}usp.br
Authors’ addresses: Simone Ladeia-Andrade and José Rodrigues Coura, Department of Tropical Medicine, Oswaldo Cruz Institute, Fiocruz, Av. Brasil 4365, Manguinhos, 21045-900 Rio de Janeiro (RJ), Brazil, Tel: 55-21-22803740 or 55-21-25621204, E-mails: shawam{at}uol.com.br and coura{at}ioc.fiocruz.br. Marcelo U. Ferreira, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1374, 05508-900 São Paulo (SP), Brazil, Tel: 55-11-30917746, Fax: 55-11-30917417, E-mail: muferrei{at}usp.br. Maria Esther de Carvalho and Izilda Curado, Laboratory of Serology, Superintendency for the Control of Endemies, Rua Paula Souza 166, Luz, 01027-000 São Paulo (SP), Brazil, Tel: 55-11-32270622 ext. 2078 or 2075, Fax: 55-11-32270622, E-mails: esther{at}sucen.sp.gov.br and icurado{at}aol.com.
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
