Understanding the clinical spectrum of complicated Plasmodium vivax malaria: a systematic review on the contributions of the Brazilian literature.

The resurgence of the malaria eradication agenda and the increasing number of severe manifestation reports has contributed to a renewed interested in the Plasmodium vivax infection. It is the most geographically widespread parasite causing human malaria, with around 2.85 billion people living under risk of infection. The Brazilian Amazon region reports more than 50% of the malaria cases in Latin America and since 1990 there is a marked predominance of this species, responsible for 85% of cases in 2009. However, only a few complicated cases of P. vivax have been reported from this region. A systematic review of the Brazilian indexed and non-indexed literature on complicated cases of vivax malaria was performed including published articles, masters' dissertations, doctoral theses and national congresses' abstracts. The following information was retrieved: patient characteristics (demographic, presence of co-morbidities and, whenever possible, associated genetic disorders); description of each major clinical manifestation. As a result, 27 articles, 28 abstracts from scientific events' annals and 13 theses/dissertations were found, only after 1987. Most of the reported information was described in small case series and case reports of patients from all the Amazonian states, and also in travellers from Brazilian non-endemic areas. The more relevant clinical complications were anaemia, thrombocytopaenia, jaundice and acute respiratory distress syndrome, present in all age groups, in addition to other more rare clinical pictures. Complications in pregnant women were also reported. Acute and chronic co-morbidities were frequent, however death was occasional. Clinical atypical cases of malaria are more frequent than published in the indexed literature, probably due to a publication bias. In the Brazilian Amazon (considered to be a low to moderate intensity area of transmission), clinical data are in accordance with the recent findings of severity described in diverse P. vivax endemic areas (especially anaemia in Southeast Asia), however in this region both children and adults are affected. Finally, gaps of knowledge and areas for future research are opportunely pointed out.

Pharmacokinetics of chloroquine in patients with malaria by P. vivax from the Western Brazilian Amazon basin.

The western Amazon basin is an important endemic area for malaria by P. vivax. In recent years, several reports showed the treatment failure with chloroquine, which can be related to resistance. The assessment of chloroquine resistance requires the evaluation of drug exposure, and when possible, the estimation of the pharmacokinetic parameters. However, there is no data on the pharmacokinetics of chloroquine in this endemic area. Moreover, the influence of the early reappearance of parasites in blood on the exposure to the drug was low exploited in the literature. The present study described the pharmacokinetic parameters of chloroquine in whole blood of adult patients with P. vivax malaria from the western Brazilian Amazon basin and compared the area under the curve (AUC) with the parasitological outcome at day 28. A total of 19 patients with parasite recurrence within 28 days and 20 patients with no recurrence were included in the study. Chloroquine was measured by high-performance liquid chromatography (HPLC). The pharmacokinetic parameters were estimated by non-compartmental modeling. The maximum concentration ranged from 1285 to 2030 ng/mL. The terminal half-life varied from 5.3 to 12.8 days. The volume of distribution from 1090 to 2340 L/kg, and the area under the curve to the last measurable concentration from 247 to 432 ng/mL.h. The pharmacokinetic parameters were similar in both groups, which suggests the lack of influence of early reappearance of parasites on chloroquine pharmacokinetics.