Molecular Epidemiology of Epidemic Severe Malaria Caused by Plasmodium vivax in the State of Amazonas, Brazil
Abstract
Malaria in South America is a major public health problem. In Brazil, most of the cases occur in the Amazon Region, particularly in the State of Amazonas. In Manaus, the capital of Amazonas, atypical cases of Plasmodium vivax infections, including patients presenting with severe thrombocytopenia and bleeding, led to the hypothesis that severe disease could be related to a particular, emergent, and more pathogenic genotype of P. vivax. The authors describe the epidemiology of malaria for the Amazonas State and city of Manaus by comparing patients admitted in the hospital to those treated as outpatients in the Fundacao de Medicina Tropical do Amazonas. Admissions due to vivax malaria increased significantly from 1997 through 2003, suggesting a change in clinical presentation. The admitted group presented higher mean parasite counts, lower platelet counts, and higher levels of liver enzymes, higher total and indirect bilirubin, and higher blood urea nitrogen when compared to the outpatient group. Clinical symptoms of severe disease, including hematuria, hemolytic anemia, and thrombocytopenia were only noted in the admitted group. Furthermore, the presence of a palpable liver was more frequent in admitted patients. Nucleic acid sequences of three genes from P. vivax, the 18S SSUrRNA Type A gene, CSP gene, and MSP-1 gene were determined. Strains from test samples were compared to each other, to the reference strains Salvador I and Belem, and to sequences retrieved from the Gene Bank. It was not possible to demonstrate the evolutionary relationship among our test samples by tests of phylogeny that incorporated sequence data for all three genes tested. The factors that may have limited the power of a combined analysis include small sample size and differences in the mechanisms and extent of variation among the genes. The retrospective study was unable to demonstrate that a particular strain of P. vivax was responsible for severe disease requiring hospitalization.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2005
- Accession Number
- ADA435458
Entities
People
- Patricia D. Santos-ciminera
Organizations
- Uniformed Services University of the Health Sciences