Perfil hematológico de uma população de região endêmica de malária da Amazônia brasileira (Anajás - PA)

Abstract

Malaria is an infectious disease caused by single-celled parasite Plasmodium genus and transmitted by Anopheles mosquitoes and anemia, leukopenia, lymphopenia and thrombocytopenia are the most common hematologic findings. The municipality of Anajás, State of Pará in the Brazilian Amazon, had the highest annual parasite incidence of malaria in 2008, with 951 cases per 1,000 inhabitants (95%). Aiming to establish the hematologic profile in that endemic area of malaria, we have analyzed hematologic data from 548 subjects classified into aged below and above 12 years old, with subdivision by gender in the last group. In total sample, we have identified 20.3% frequency of malaria (7.1% of P. falciparum and 13.2% of P. vivax) with higher frequencies in rural areas with 61.5% of malaria in Luciana locality (46.2% of P.vivax and 15.3% of P. falciparum) and 34% of malaria in Vencedora locality (28.3% of P. vivax and 5.7% of P. falciparum) against 17.9% of malaria in urban areas (10.9% of P. vivax and 7.0% of P. falciparum). Children under 12 years old negative from malaria have shown mean values of hemoglobin lower than individuals with malaria and the reference values, which may indicate that other causes of anemia could be associated and malaria is not a determinant cause of anemia in children, or could have parasitic immunity in the population. Leukopenia was a common finding, but observed more frequently in children below 12 years old with malaria (30.4%) compared to subjects over 12 years old (10.2%), which, however, can not be related to malaria since the negative subjects have shown also high frequency (26.1%). Lymphopenia among children below 12 years old was found only in carriers of malaria by P. falciparum (8.7%), near the low frequency of subjects negative for malaria (9.0%) while in group above 12 years old the frequency of lymphopenia was higher in patients with malaria (21.5%). Increase in MED value (mean of basophils, eosinophils and monocytes) found in children under 12 years old with malaria, suggests that eosinophilia and/or monocytosis could be related to malaria. Thrombocytopenia has occurred in low frequency (11.7%) among subjects with malaria, probably because the low rates of anemia or low concentrations of anti-plasmodium antibodies circulating in the population. The atypical hematolic profile observed mainly in children below 12 years old, suggests that further research should be conducted in Anajás population to clarify the true role of malaria and other biological and socio-economic factors in hematological profile of that population.