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Plasmodium vivax chloroquine resistance and anemia in the western Brazilian Amazon

In Latin America, data on chloroquine (CQ)-resistant Plasmodium vivax is limited, even with the current research efforts to sustain an efficient malaria control program in all these endemic countries, where malaria still is a major public health issue.

This study estimated in vivo CQ-resistance in uncomplicated patients with P. vivax in use of CQ and primaquine simultaneously, in the Brazilian Amazon. From a total of 135 enrolled subjects, who accomplished the 28-day follow-up, parasitological failure was observed in 7 (5.2%) patients, in which plasmatic CQ and desethylchloroquine (DCQ) concentrations were above 100ng/dL. Univariate analysis showed that previous exposure to malaria and a higher initial mean parasitemia were associated to resistance, but not to age or gender.

In the multivariate analysis only high initial parasitemia remained significant. Hemoglobin levels were similar in the beginning of the follow-up and not associated to parasitemia. However, in D3 and D7, hemoglobin levels were significantly lower within patients presenting CQ-resistance. The pvdhfr, pvmrp1, pvmdr1 and pvdhps gene mutations were not related to resistance in this small sample. P. vivax CQ-resistance is already a problem in the Brazilian Amazon, what could be to some extent associated to the simultaneous report of anemia triggered by this parasite, a common complication of the disease in most of the endemic areas.

Plasmodium vivax chloroquine resistance and anemia in the western Brazilian Amazon

In Latin America, data on chloroquine (CQ)-resistant Plasmodium vivax is limited, even with the current research efforts to sustain an efficient malaria control program in all these endemic countries, where malaria still is a major public health issue.

This study estimated in vivo CQ-resistance in uncomplicated patients with P. vivax in use of CQ and primaquine simultaneously, in the Brazilian Amazon. From a total of 135 enrolled subjects, who accomplished the 28-day follow-up, parasitological failure was observed in 7 (5.2%) patients, in which plasmatic CQ and desethylchloroquine (DCQ) concentrations were above 100ng/dL. Univariate analysis showed that previous exposure to malaria and a higher initial mean parasitemia were associated to resistance, but not to age or gender.

In the multivariate analysis only high initial parasitemia remained significant. Hemoglobin levels were similar in the beginning of the follow-up and not associated to parasitemia. However, in D3 and D7, hemoglobin levels were significantly lower within patients presenting CQ-resistance. The pvdhfr, pvmrp1, pvmdr1 and pvdhps gene mutations were not related to resistance in this small sample. P. vivax CQ-resistance is already a problem in the Brazilian Amazon, what could be to some extent associated to the simultaneous report of anemia triggered by this parasite, a common complication of the disease in most of the endemic areas.