Marcadores de estresse oxidativo em plasma e eritrócitos de pacientes com Malária Vivax grave

Abstract

The human malaria is an infectious disease, febrile, acute or chronic, caused by protozoa transmitted by vectors, being the disease more widely distributed in the world and one of the most prevalent parasitic diseases today. About 300 to 500 million cases occur annually and about 1 to 2 million people - mostly children - die from malaria. In the state of Amazonas, between january 2007 and march 2009, 22,081 cases of malaria were diagnosed and reported, with the largest record (14,249) in 2007. Although Plasmodium vivax malaria is considered a benign form of the disease with a low mortality rate in relation to Plasmodium falciparum, it can cause a serious disease where complications such as jaundice, severe anemia, renal failure and pulmonary complications are described. Oxidative stress occurs when there is an imbalance in the concentration of oxidants, free radicals, and antioxidants, such as enzymes, vitamins C and E, β-carotene. During the malaria disease, oxidative stress may be developed by two mechanisms: by the parasite, when it is to reproduce, generates reactive species and the host immune system, which makes use of these reactive species to try to combat the parasite. In order to study oxidative stress in patients with severe vivax malaria who developed jaundice in the course of the disease in plasma and erythrocytes, and also to check the influence of this high concentration of bilirubin in oxidative stress, the following groups of patients was studied: non-severe malaria , severe malaria presenting jaundice, concurrent malaria and dengue, healthy patients with no history of malaria (control group) and one patient with deficiency in the enzyme glucose-6-phosphate dehydrogenase which contracted malaria. In all patients were measured the levels of antioxidant enzymes and lipid peroxidation marker malondialdehyde on day zero (when diagnosed with malaria) and on day fourteen (free of symptoms and parasitemia). The levels of malondialdehyde and the enzymes celuroplasmin, lactate dehydrogenase and glutathione reductase were increased (p <0.02) in plasma of patients with severe malaria compared with the control group, unlike the enzymes catalase, superoxide dismutase and thioredoxin reductase where levels were decreased (p <0.03) compared to the control group. The levels of glutathione reductase and malondialdehyde marker also showed significantly higher levels in severe malaria groups when compared with non-severe malaria group. The correlation between glutathione reductase and total bilirubin was significant (p < 0.0001) in all patients of each group. Patients who developed malaria and dengue fever showed levels of oxidative stress similar to patients with severe malaria. With all these results, we conclude the patients with severe vivax malaria who developed jaundice had a higher oxidative stress than the patients who contracted the disease in milder form. Thus, these high concentrations of bilirubin may develop the role of signaling to oxidation in patients with malaria