Early transmission of sensitive strain slows down emergence of drug resistance in Plasmodium vivax

摘要

The main strategy to treat and prevent malaria still relies on the use of drugs targeting Plasmodium falciparum and Plasmodium vivax parasites. Since the worldwide number of cases is still large, there is a risk of emergence of drug resistance, which is precisely the case of resistance of chloroquine for P. falciparum and P. vivax in some countries. The spread of drug resistance challenges malaria control programs due to treatment failures and consequent lower drug efficacy. This phenomenon is more frequent, accelerated, and studied in P. falciparum cases but P. vivax also presents drug resistance in some areas and the particular life cycle of P. vivax with relapses due to its latent form, an earlier transmission and more common low parasitemia densities that imposes detection difficulties. We developed a mathematical model to study drug-resistance emergence in P. vivax finding that early transmission of drug-sensitive parasites as well as infected humans without symptoms delays drug resistance. As a consequence, however, the number of P. vivax cases decreases less than the number of P. falciparum cases. These results suggest that earlier attention of all infected humans, including individuals without symptoms, might help to decrease P. vivax cases but also accelerate the spread of drug resistance.