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Anaemia is amongst the major complications of malaria, a major public health problem in the Amazon Region in Latin America. We examined the haemoglobin (Hb) concentrations of malaria-infected patients and compared it to that of malaria-negative febrile patients and afebrile controls. The haematological parameters of febrile patients who had a thick-blood-smear performed at an infectious diseases reference centre of the Brazilian Amazon between December 2009-January 2012 were retrieved together with clinical data. An afebrile community control group was composed from a survey performed in a malaria-endemic area. Hb concentrations and anaemia prevalence were analysed according to clinical-epidemiological status and demographic characteristics. In total, 7,831 observations were included. Patients with Plasmodium falciparum infection had lower mean Hb concentrations (10.5 g/dL) followed by P. vivax-infected individuals (12.4 g/dL), community controls (12.8 g/dL) and malaria-negative febrile patients (13.1 g/dL) (p < 0.001). Age, gender and clinical-epidemiological status were strong independent predictors for both outcomes. Amongst malaria-infected individuals, women in the reproductive age had considerably lower Hb concentrations. In this moderate transmission intensity setting, both vivax and falciparum malaria are associated with reduced Hb concentrations and risk of anaemia throughout a wide age range.

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Anaemia is amongst the major complications of malaria, a major public health problem in the Amazon Region in Latin America. We examined the haemoglobin (Hb) concentrations of malaria-infected patients and compared it to that of malaria-negative febrile patients and afebrile controls. The haematological parameters of febrile patients who had a thick-blood-smear performed at an infectious diseases reference centre of the Brazilian Amazon between December 2009-January 2012 were retrieved together with clinical data. An afebrile community control group was composed from a survey performed in a malaria-endemic area. Hb concentrations and anaemia prevalence were analysed according to clinical-epidemiological status and demographic characteristics. In total, 7,831 observations were included. Patients with Plasmodium falciparum infection had lower mean Hb concentrations (10.5 g/dL) followed by P. vivax-infected individuals (12.4 g/dL), community controls (12.8 g/dL) and malaria-negative febrile patients (13.1 g/dL) (p < 0.001). Age, gender and clinical-epidemiological status were strong independent predictors for both outcomes. Amongst malaria-infected individuals, women in the reproductive age had considerably lower Hb concentrations. In this moderate transmission intensity setting, both vivax and falciparum malaria are associated with reduced Hb concentrations and risk of anaemia throughout a wide age range.

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INTRODUCTION: In remote areas of the Amazon Region, diagnosis of malaria by microscopy is practically impossible. This study aimed to evaluate the performance of two rapid diagnostic tests (RDTs) targeting different malaria antigens stored at room temperature in the Brazilian Amazon Region. METHODOLOGY: Performance of the OptiMal Pf/Pan test and ICT-Now Pf/Pan test was analyzed retrospectively in 1,627 and 1,602 blood samples, respectively. Tests were performed over a 15-month period. Kits were stored at room temperature in five community health centres located in the Brazilian Amazon Region. RDT results were compared with thick blood smear (TBS) results to determine sensitivity, specificity, and accuracy of the RDT. RESULTS: The sensitivities of the OptiMal Pf/Pan test were 79.7% for Plasmodium falciparum malaria diagnosis and 85.7% for non-P. falciparum infections. The results showed a crude agreement of 88.5% for P. falciparum, and 88.3% for non-P. falciparum infections (Kappa index = 0.74 and 0.75, respectively). For the ICT-Now Pf/Pan test (CI 95%), the sensitivities were 87.9% for P. falciparum malaria diagnosis and 72.5% for non-P. falciparum infection. Crude agreement between the ICT-Now Pf/Pan test and TBS was 91.4% for P. falciparum and 79.7% for non-P. falciparum infection. The Kappa index was 0.81 and 0.59 for the final diagnosis of P. falciparum and non-P. falciparum, respectively. Higher levels of parasitaemia were associated with higher crude agreement between RDT and TBS. CONCLUSIONS: The sensitivities of RDTs stored at room temperature over a 15-month period and performed in field conditions were lower than those previously reported.

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We describe a case series of 17 patients hospitalized in Manaus (western Brazilian Amazon) with PCR-confirmed Plasmodium vivax infection who were treated with chloroquine and primaquine. The major complications were jaundice and severe anemia. No in vivo chloroquine resistance was detected. These data help characterize the clinical profile of severe P. vivax malaria in Latin America.

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Over the past 2 decades, the Amazon region of Brazil has experienced reemergence of Plasmodium vivax malaria, with reported occurrence of severe disease. The frequency and manifestations of this severe disease are unlike previous clinical experience. The hypothesis has been raised that the occurrence of severe disease may relate to the emergence of a variant form of the parasite. To test this hypothesis, we conducted a retrospective cohort study of P. vivax strains in the State of Amazonas. We determined nucleic acid sequences of segments of three genes, the 18S SSUrRNA Type A gene, the circumsporozoite surface protein (CSP) gene and the MSP-1 gene. Sequences were determined for parasites infecting 11 hospitalized (Inpatients) and 21 non-hospitalized (Outpatients) patients. We observed two common polymorphisms in the 18S SSUrRNA Type A gene; a thymidine (T)/adenine (A) polymorphism at residue 117 was significantly more common in the Inpatient group (p<0.05). Types of variation in the CSP gene included the numbers of repeat nonapeptide segments, alanine/aspartic acid polymorphism at position 5 of the nonapeptide repeat, and sporadic mutations. Alanine was more common as the fifth residue of the nonapeptide repeat in Inpatients and in strains causing second infections (both, p<0.05). Synonymous substitutions of the common repeat sequence occurred frequently in codons 1, 2, and 7, while the mutations at codon 5 were always non-synonymous, indicating that variation at codon 5 reflected selective pressure. Among MSP-1 gene sequences, recombination among progenitor strains, related to the Salvador I and Belém strains, was the main source of diversity. Phylogenetic analyses that incorporated sequence data for all three genes tested did not reveal clustering of sequences from inpatients. Our data do not affirm that the hypothesis that severe P. vivax disease in Amazonas is related to emergence of a new variant, but do suggest that variation in the fifth position of the CSP gene nonapeptide repeat may relate to disease manifestations.

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We focused on rates of malaria in the state of Amazonas and city of Manaus, Brazil. Plasmodium vivax accounted for an increased number and rate of hospital admissions, while P. falciparum cases decreased. Our observations on malaria epidemiology suggest that the increased hospitalization rate could be due to increased severity of P. vivax infections.

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Estamos relatando pela primeira vez um paciente com malária por Plasmodium vivax que mostrou resistência R2 à cloroquina e resistência R3 à mefloquina na Amazônia brasileira, de acordo com os critérios clínicos da OMS para resistência da malária. A falha foi observada com cloroquina oral, näo supervisionada, cloroquina oral administrada sob rigorosa supervisäo e com mefloquina no mesmo esquema. A paciente curou com o artesunato oral

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