Polymorphism in the pvcrt-o and pvmdr-1 genes of Plasmodium vivax associated with a better prognosis for malaria.

The early molecular identification of strains of Plasmodium vivax that have a worse prognosis is important to stratify the risk of complications and choice of conduct made by medical teams. Thus, the aim of the present study was to associate the presence of polymorphisms in the pvmdr-1 and pvcrt-o resistance genes of P. vivax in patients with better or worse prognosis. This cross-sectional epidemiological study was conducted based on data obtained from the records of 120 patients diagnosed with malaria in the Brazilian Amazon. The T958M and F1076L mutations of the pvmdr-1 gene had a frequency of 3.3 and 4.2%, respectively, and primo-infected patients had a 17 times greater chance of being infected with protozoa with the T958M mutation compared to patients with previous episodes. Regarding pvcrt-o, the C393T and T786C polymorphisms had a frequency of 14.2 and 3.3%, respectively, and self-declared white patients had a 3.1 times greater chance of being infected with protozoa with the C393T polymorphism. In addition, patients with this pvcrt-o polymorphism had lower concentrations of C-reactive protein, indicating a better prognosis. These data present clues of genetic indicators useful for assessing the virulence of the parasite and the prognosis of patients with vivax malaria.

Polymorphism in the pvcrt-o and pvmdr-1 genes of Plasmodium vivax associated with a better prognosis for malaria

@#The early molecular identification of strains of Plasmodium vivax that have a worse prognosis is important to stratify the risk of complications and choice of conduct made by medical teams. Thus, the aim of the present study was to associate the presence of polymorphisms in the pvmdr-1 and pvcrt-o resistance genes of P. vivax in patients with better or worse prognosis. This cross-sectional epidemiological study was conducted based on data obtained from the records of 120 patients diagnosed with malaria in the Brazilian Amazon. The T958M and F1076L mutations of the pvmdr-1 gene had a frequency of 3.3 and 4.2%, respectively, and primo-infected patients had a 17 times greater chance of being infected with protozoa with the T958M mutation compared to patients with previous episodes. Regarding pvcrt-o, the C393T and T786C polymorphisms had a frequency of 14.2 and 3.3%, respectively, and self-declared white patients had a 3.1 times greater chance of being infected with protozoa with the C393T polymorphism. In addition, patients with this pvcrt-o polymorphism had lower concentrations of C-reactive protein, indicating a better prognosis. These data present clues of genetic indicators useful for assessing the virulence of the parasite and the prognosis of patients with vivax malaria.

Infection of Anopheles darlingi fed on patients infected with Plasmodium vivax before and during treatment with chloroquine in Costa Marques, Rondonia, Brazil.

Patients with asexual and sexual parasites of Plasmodium vivax were treated orally with 600 mg of chloroquine diphosphate at hour zero, followed by 300 mg at 8, 24 and 48 hr. Anopheles darlingi were fed before the first dose (-0.5 hr) and at 0.5, 1, 2, 4, 6, 8, 9, 10, 11, 12, 20, 24, 36, 48, 60, and 72 hr later. Mosquitoes were examined for oocysts on day 8 and sporozoites on day 15 after infection. The frequency of infected mosquitoes and the mean number of oocysts were lower in mosquitoes that fed on patients 2-4 hr after the initial dose of chloroquine than in mosquitoes fed before treatment and at 0.5 and 1 hr. This sporontocidal effect was temporary, since the frequency of infected mosquitoes and the mean number of oocysts increased in mosquitoes fed 4-8 hr after the first dose. Nearly all mosquitoes fed on patients after the third dose of chloroquine, at 24 hr, were negative for P. vivax oocysts. Oocysts in mosquitoes fed on patients before, during, and after chloroquine treatment appeared normal and produced sporozoites. We conclude that chloroquine affects either the gametocytes, fertilization, zygotes, and/or ookinetes of P. vivax, but not subsequent stages of development.