Morphological atypia and molecular profile of Plasmodium vivax: Findings from an outbreak in the Brazilian Amazon.

This study aimed to perform morphological and molecular analyses of parasites isolated from the blood of malaria-infected individuals during an outbreak in the Microregion of Cametá, State of Pará, Brazilian Amazon. A total of 260 positive samples were identified by microscopy as Plasmodium vivax; however, in three samples, forms considered unusual for the species were found and defined as morphological atypia of P. vivax. Single P. vivax infection was confirmed by qPCR in all samples. Among 256 genotyped samples, the VK247 genotype alone was identified in 255 samples, and the VK210 genotype was found in only one. The study showed that this malaria outbreak was caused by the etiological agent P. vivax, and for the first time, morphological atypia was described in isolates circulating in Brazil. Likewise, for the first time, the VK247 genotype was detected predominantly in single infections in an area of the State of Pará, which may suggest a greater circulation of the genotype in the region.

Title: Atypie morphologique et profil moléculaire de Plasmodium vivax : résultats issus d'une épidémie en Amazonie brésilienne. Abstract: Cette étude visait à effectuer des analyses morphologiques et moléculaires de parasites isolés du sang d'individus infectés par le paludisme lors d'une épidémie dans la microrégion de Cametá, État du Pará, Amazonie brésilienne. Au total, 260 échantillons positifs ont été identifiés par microscopie comme Plasmodium vivax mais dans trois échantillons, des formes considérées comme inhabituelles pour l'espèce ont été trouvées et définies comme des atypies morphologiques de P. vivax. Une infection simple à P. vivax a été confirmée par qPCR dans tous les échantillons. Sur 256 échantillons génotypés, le génotype VK247 seul a été identifié dans 255 échantillons, et le génotype VK210 a été trouvé dans un seul échantillon. L'étude a montré que cette épidémie de paludisme était causée par l'agent étiologique P. vivax et, pour la première fois, une atypie morphologique a été décrite dans des isolats circulant au Brésil. De même, pour la première fois, le génotype VK247 a été détecté principalement dans des infections uniques dans une zone de l'État de Pará, ce qui peut suggérer une plus grande circulation du génotype dans la région.

Evaluation of Histidine-Rich Proteins 2 and 3 Gene Deletions in Plasmodium falciparum in Endemic Areas of the Brazilian Amazon.

Histidine-rich proteins 2 and 3 gene (pfhrp2 and pfhrp3) deletions affect the efficacy of rapid diagnostic tests (RDTs) based on the histidine-rich protein 2 (HRP2), compromising the correct identification of the Plasmodium falciparum species. Therefore, molecular surveillance is necessary for the investigation of the actual prevalence of this phenomenon and the extent of the disappearance of these genes in these areas and other South American countries, thus guiding national malaria control programs on the appropriate use of RDTs. This study aimed to evaluate the pfhrp2 and pfhrp3 gene deletion in P. falciparum in endemic areas of the Brazilian Amazon. Aliquots of DNA from the biorepository of the Laboratory of Basic Research in Malaria, Evandro Chagas Institute, with a positive diagnosis for P. falciparum infection as determined by microscopy and molecular assays, were included. Monoinfection was confirmed by nested-polymerase chain reaction assay, and DNA quality was assessed by amplification of the merozoite surface protein-2 gene (msp2). The pfhrp2 and pfhrp3 genes were amplified using primers for the region between exons 1 and 2 and for all extension of exon 2. Aliquots of DNA from 192 P. falciparum isolates were included in the study, with 68.7% (132/192) from the municipality of Cruzeiro do Sul (Acre) and 31.3% (60/192) from Manaus (Amazonas). Of this total, 82.8% (159/192) of the samples were considered of good quality. In the state of Acre, 71.7% (71/99) showed pfhrp2 gene deletion and 94.9% (94/99) showed pfhrp3 gene deletion, while in the state of Amazonas, 100.0% (60/60) of the samples showed pfhrp2 gene deletion and 98.3% (59/60) showed pfhrp3 gene deletion. Moreover, 79.8% (127/159) of isolates displayed gene deletion. Our findings confirm the presence of a parasite population with high frequencies of pfhrp2 and pfhrp3 gene deletions in the Brazilian Amazon region. This suggests reconsidering the use of HRP2-based RDTs in the Acre and Amazonas states and calls attention to the importance of molecular surveillance and mapping of pfhrp2/pfhrp3 deletions in this area and in other locations in the Amazon region to guarantee appropriate patient care, control and ultimately contribute to achieving P. falciparum malaria elimination.

Correlation between Plasmodium vivax variants in Belém, Pará State, Brazil and symptoms and clearance of parasitaemia.

The aim of this study was to determine how different types of P. vivax affect clinical symptoms and parasitaemia clearance. Blood was collected from individuals from Pará State, Brazil. The patients were treated as chloroquine plus primaquine. P. vivax were typed daily till D7 and again on D30. Now we can confirm a previously reported correlation between P. vivax genotype and response to chloroquine. Clinical symptoms do not allow for objective identification of different P. vivax types in the Brazilian Amazon, since the VK247 and P. vivax-like have only been detected in mixed infections.

Performance of an immunochromatography test for vivax malaria in the Amazon region, Brazil.

The study was carried out to evaluate the diagnostic performance of the ICT malaria Pf/Pv test for vivax malaria diagnosis in Bel m, Amazon region, Brazil. The results of blood malaria parasites examination using an immunochromatography test were compared with thick blood film (TBF) examination. It was also evaluated the performance of this test storaged at three different temperatures (25 degree C, 30 degree C, and 37 degree C) for 24 hours before use. Overall sensitivity of ICT Pf/Pv was 61.8% with a specificity of 100%, positive and negative predictive value of 100% and 71.8%, respectively and accuracy of 80.6%. The test sensitivity was independent of the parasite density. This test needs to be further reviewed in order to have better performance for P. vivax malaria diagnosis.

In vitro antiplasmodial activity of extract and constituents from Esenbeckia febrifuga, a plant traditionally used to treat malaria in the Brazilian Amazon.

Esenbeckia febrifuga (Rutaceae) is a plant traditionally used to treat malaria in the Brazilian Amazon region. Ethanol extract of stems displayed a good antiplasmodial activity against Plasmodium falciparum strains W-2 (IC(50) 15.5+/-0.71 microg/ml) and 3 D7 (IC(50) 21.0+/-1.4 microg/ml). Two coumarins (bergaptene 1 and isopimpinellin 2), five alkaloids (flindersiamine 3, kokusaginine 4, skimmiamine 5, gamma-fagarine 6 and 1-hydroxy-3-methoxy-N-methylacridone, 7), besides a limonoid (rutaevine 8), have been isolated for the first time from this species. Antiplasmodial activity of compounds 3, 5-8 has been evaluated in vitro against P. falciparum strains (W-2 and 3D7) and the furoquinolines 5 and 6 were the most potent displaying IC(50) values <50 microg/ml; flindersiamine (3) showed a weak activity while alkaloid 7 and rutaevine (8) were inactive (IC(50)>100 microg/ml).

Risco de transmissão de malária humana em área de implantação de projeto de prospecção mineral, município de Juruti, Estado do Pará / Human malaria transmission risk in an implementation area of mineral prospection, Juruti Municipality, Para State, Brazil

Este estudo objetivou avaliar o risco de transmissão de malária humana em áreas de influência do projeto Juruti no período 2006 a 2008. Um total de 976 mosquitos anofelinos foram capturados por atração humana protegida, identificados e processados para determinação de infectividade pelo teste de imunoensaio (ELISA) e, parte deles (10por cento) para taxa de paridade. Para o inquérito hemoscópico, foram feitas duas coletas (setembro/2007 na comunidade Capiranga e invasão Nova Vitória e março/2008 somente na última) utilizando-se o método da gota expressa (GE). Foram identificadas oito espécies de mosquitos anofelinos, com predomínio da espécie An. albitarsis s.l (76,8por cento) cuja taxa de paridade foi de 9,6por cento. A taxa de infecção foi zero para os primeiros dois anos de estudo e de 0,5por cento em 2008, quando um exemplar de An. albitarsis s.l coletado na comunidade de Santa Maria foi positivo para P. vivax-VK247. O índice de picada homem/hora (IPHH) variou de 0,1 a 8,1. Todas as 148 amostras de sangue foram negativas pela GE. Concluiu-se, portanto, que o risco de transmissão de malária na área estudada é baixo, apesar da presença de mosquitos vetores. Contudo, faz-se necessária vigilância permanente por causa, principalmente, do intenso fluxo migratório gerado pelo projeto.

Controle da transmissäo da malária em área de garimpo no Estado do Amapá com participaçäo da iniciativa privada / Control of malaria transmission in a gold-mining area in Amapá State, Brazil, with participation by private enterprise

Reporta a caracterizaçäo epidemiológica da malária, seguida da implantaçäo de um programa de controle da endemia em uma área de garimpo, localizada ao norte do estado do Amapá. Considera-se a influência desta regiäo no número total de casos do estado e o impacto da doença na populaçäo representada pelos funcionários e empreiteiros da Mineraçäo Novo Astro S/A, bem como pela comunidade da Vila de Lourenço, Município de Calçoene, Amapá e garimpos adjacentes. O impacto das açöes de controle adotadas no âmbito do programa, caracterizam-se pela significativa reduçäo da incidência da malária na área e a reduçäo da morbi-mortalidade. Ressalta-se a importância da participaçäo da iniciativa privada, principalmente aquelas que desenvolvem projetos de grande porte na regiäo Amazônica brasileira, no controle das endemias prevalentes na regiäo, particularmente a malária.

Correlation between Plasmodium vivax variants in Belém, Pará State, Brazil and symptoms and clearance of parasitaemia

The aim of this study was to determine how different types of P. vivax affect clinical symptoms and parasitaemia clearance. Blood was collected from individuals from Pará State, Brazil. The patients were treated as chloroquine plus primaquine. P. vivax were typed daily till D7 and again on D30. Now we can confirm a previously reported correlation between P. vivax genotype and response to chloroquine. Clinical symptoms do not allow for objective identification of different P. vivax types in the Brazilian Amazon, since the VK247 and P. vivax-like have only been detected in mixed infections

Performance of an immunochromatography test for virax malaria in the Amazon region, Brazil

Avaliaçäo do teste ICT malaria Pf/PvTM para o diagnóstico da malária por P. vivax em Belém, Estado do Pará. Foram comparados os resultados do teste imunocromatográfico com a gota espessa (GE) e avaliados o comportamento desse teste, estocado a três temperaturas distintas (250C/ 300C/ 370C), 24 horas antes de seu uso. A sensibilidade do ICT malaria Pf/PvTM foi de 61,8 por cento com especificidade de 100por cento, valores preditivo positivo e negativo de 100 por cento e 71,8 por cento, respectivamente, e acurácia de 80,67por cento. A sensibilidade desse teste foi independente da densidade parasitária. Este teste necessita de reavaliaçäo para melhorar o seu comportamento no diagnóstico da malária por P. vivax