Abstract
BackgroundThe emergence and spread of Plasmodium falciparum and Plasmodium vivax resistance to available anti-malarial drugs represents a major drawback in the control of malaria and its associated morbidity and mortality. The aim of this study was to evaluate the chemoresistance profile of P. falciparum and P. vivax to commonly used anti-plasmodial drugs in a malaria-endemic area in the Brazilian Amazon.MethodsThe study was carried out in Manaus (Amazonas state), in the Brazilian Amazon. A total of 88 P. falciparum and 178 P. vivax isolates was collected from 2004 to 2007. The sensitivity of P. falciparum isolates was determined to chloroquine, quinine, mefloquine and artesunate and the sensitivity of P. vivax isolates was determined to chloroquine and mefloquine, by using the colorimetric DELI test.ResultsAs expected, a high prevalence of P. falciparum isolates resistant to chloroquine (78.1%) was observed. The prevalence of isolates with profile of resistance or decreased sensitivity for quinine, mefloquine and artesunate was 12.7, 21.2 and 11.7%, respectively. In the case of P. vivax, the prevalence of isolates with profile of resistance for chloroquine and mefloquine was 9.8 and 28%, respectively. No differences in the frequencies of isolates with profile of resistance or geometric mean IC50s were seen when comparing the data obtained in 2004, 2005, 2006 and 2007, for all tested anti-malarials.ConclusionsThe great majority of P. falciparum isolates in the Brazilian malaria-endemic area remain resistant to chloroquine, and the decreased sensitivity to quinine, mefloquine and artesunate observed in 10–20% of the isolates must be taken with concern, especially for artesunate. Plasmodium vivax isolates also showed a significant proportion of isolates with decreased sensitivity to chloroquine (first-line drug) and mainly to mefloquine. The data presented here also confirm the usefulness of the DELI test to generate results able to impact on public health policies.
Highlights
The emergence and spread of Plasmodium falciparum resistance to anti-malarial drugs represent a major drawback in the control of malaria and its associated morbidity and mortality
The same was true in Brazil, where the first report of P. falciparum resistance to chloroquine was in the 1960s [4] and, by 1990, more than 95% of P. falciparum isolates circulating in malaria endemic areas were resistant to chloroquine [8]
A total of 88 P. falciparum and 178 P. vivax samples was collected from malaria patients from 2004 to 2007
Summary
The emergence and spread of Plasmodium falciparum and Plasmodium vivax resistance to available anti-malarial drugs represents a major drawback in the control of malaria and its associated morbidity and mortality. The emergence and spread of Plasmodium falciparum resistance to anti-malarial drugs represent a major drawback in the control of malaria and its associated morbidity and mortality. Since the first reports of P. falciparum parasites with reduced sensitivity to chloroquine [4,5,6,7], the resistance to this drug spread rapidly throughout the world In many places, it became no longer effective and had to be substituted by other drugs, more expensive and in many cases presenting considerable side effects. The same was true in Brazil, where the first report of P. falciparum resistance to chloroquine was in the 1960s [4] and, by 1990, more than 95% of P. falciparum isolates circulating in malaria endemic areas were resistant to chloroquine [8]
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