Recent studies favor increased copy number of pfmdr1 and not pfmdr1 poly-morphisms as the most important determinant of in vivo resistance to Mefloquine and reduced sensitivity in vitro to Artesunate and Lumefantrine.
In a retrospective molecular survey, we assessed the frequency of occurrence of increased copy number of the pfmdr1 – gene in parasite DNA, obtained during two time periods, 2005 [n=41] and 2009 [n=27] from patients living/working in geographically different locations throughout the country, including mining areas.
From the samples with a quantifiable copy number, 89% exhibited a single copy of Plasmodium falciparum multidrug resistance gene pfmdr1, while 11% of multicopy samples could be detected.
Our results contribute to the status in South America since reports on pfmdr1 copy number in South America have been limited to Peru, where only single copy isolates were detected and Venezuela, with 12 % of multicopy isolates.
Our results augment the results of Venezuela that increasing pfmdr1 copy number is also surfacing in South America, warranting caution for emerging resistance.