Abstract Malaria is a disease caused by Plasmodium spp. protozoa. The ability of Plasmodium to develop resistance to current antimalarial drugs makes the study of chemotherapeutic alternatives extremely important. This study aimed to evaluate the antimalarial activity of compound 3286938 (1-(3-benzyloxy-4-methoxy-phenyl)-3-(3,4,5-trimethoxy-phenyl)-propan-1-one), which presents in its structure a 3,4,5-trimethoxyphenyl group, in vitro, using the W2 strain of P. falciparum and against circulating strains of P. vivax and P. falciparum from the state of Rondônia. The compound 3286938 obtained an IC50 of 24.4 µM against the W2 strain of P. falciparum, and against the circulating strains, it presented a median (MD)=38.7 µM for P. vivax and MD=6.7 µM for P. falciparum. As for toxicity, 3286938 showed CC50 > 500 µM for VERO and HepG2 strains with a selectivity index greater than 12.9, a ratio calculated for P. falciparum and P. vivax regarding Vero and HepG2 cells. The compound was not considered hemolytic in in vitro assays, thus indicating the specificity of its antiplasmodial action. Based on the results presented, and considering the unprecedented character of the compound, it can be concluded that 3286938 was shown to be promising for complementary in vitro and in vivo studies aiming to produce effective antiplasmodial action.

The PfCLAG9 has been extensively studied because their immunogenicity. Thereby, the gene product is important for therapeutics interventions and a potential vaccine candidate. Antibodies against synthetic peptides corresponding to selected sequences of the Plasmodium falciparum antigen PfCLAG9 were found in sera of falciparum malaria patients from Rondônia, in the Brazilian Amazon. Much higher antibody titres were found in semi-immune and immune asymptomatic parasite carriers than in subjects suffering clinical infections, corroborating original findings in Papua Guinea. However, sera of Plasmodium vivax patients from the same Amazon area, in particular from asymptomatic vivax parasite carriers, reacted strongly with the same peptides. Bioinformatic analyses revealed regions of similarity between P. falciparum Pfclag9 and the P. vivax ortholog Pvclag7. Indirect fluorescent microscopy analysis showed that antibodies against PfCLAG9 peptides elicited in BALB/c mice react with human red blood cells (RBCs) infected with both P. falciparum and P. vivax parasites. The patterns of reactivity on the surface of the parasitised RBCs are very similar. The present observations support previous findings that PfCLAG9 may be a target of protective immune responses and raises the possibility that the cross reactive antibodies to PvCLAG7 in mixed infections play a role in regulate the fate of Plasmodium mixed infections.

In this study, we determined whether the treatment of asymptomatic parasites carriers (APCs), which are frequently found in the riverside localities of the Brazilian Amazon that are highly endemic for malaria, would decrease the local malaria incidence by decreasing the overall pool of parasites available to infect mosquitoes. In one village, the treatment of the 19 Plasmodium falciparum-infected APCs identified among the 270 residents led to a clear reduction (Z = -2.39, p = 0.017) in the incidence of clinical cases, suggesting that treatment of APCs is useful for controlling falciparum malaria. For vivax malaria, 120 APCs were identified among the 716 residents living in five villages. Comparing the monthly incidence of vivax malaria in two villages where the APCs were treated with the incidence in two villages where APCs were not treated yielded contradictory results and no clear differences in the incidence were observed (Z = -0.09, p = 0.933). Interestingly, a follow-up study showed that the frequency of clinical relapse in both the treated and untreated APCs was similar to the frequency seen in patients treated for primary clinical infections, thus indicating that vivax clinical immunity in the population is not species specific but only strain specific.

Since around 1723, on the occasion of its initial colonization by Europeans, Rondonia has received successive waves of immigrants. This has been further swelled by individuals from northeastern Brazil, who began entering at the beginning of the twentieth century. The ethnic composition varies across the state according to the various sites of settlement of each wave of immigrants. We analyzed the frequency of the CCR5L32 allele of the CCR5 chemokine receptor, which is considered a Caucasian marker, in five sample sets from the population. Four were collected in Porto Velho, the state capital and the site of several waves of migration. Of these, two, from the Hospital de Base were comprised of HB Mothers and HB Newborns presenting allele frequencies of 3.5% and 3.1%, respectively, a third from the peri-urban neighborhoods of Candelária/Bate-Estaca (1.8%), whereas a fourth, from the Research Center on Tropical Medicine/CEPEM (0.6%), was composed of malaria patients under treament. The fifth sample (3.4%) came from the inland Quilombola village of Pedras Negras. Two homozygous individuals (CCR5Δ32/CCR5Δ32) were detected among the HB Mother samples. The frequency of this allele was heterogeneous and higher where the European inflow was more pronounced. The presence of the allele in Pedras Negras revealed European miscegenation in a community largely comprising Quilombolas.

Flavivirus é um gênero dos vírus transmitidos por artrópode da família Flaviviridae e, no Brasil, são isolados onze Flavivirus diferentes. Foi coletado o sangue de um agricultor, no município de Theobroma situado a 320km de distância da Cidade de Porto Velho, capital do Estado Brasileiro, Rondônia. Para isolamento viral, foi usado cérebro de camundongos recém-nascido, seguido por RT-PCR com primers universais específicos de Flavivirus. Nós obtivemos fragmentos com 958bp e 800bp de comprimento. Ao Blast das sequências obtivemos 91% de similaridade com uma sequência do vírus de Cacipacoré.

Flavivirus is a genus of arthropod-transmitted viruses of the family Flaviviridae, and in Brazil, up to eleven different Flavivirus have been isolated. We collected blood from farmers in the municipality of Theobroma, which is located 320km from the City of Porto Velho, the former capital of the Brazilian State of Rondônia. For viral isolation, we used newborn mouse brain, followed by RT-PCR with specific universal Flavivirus primers. We obtained fragments 958bp and 800bp in length. Based on BLAST, these sequences were 91% similar to a sequence of Cacipacore virus.

Em Rondônia, prevê-se a construção de mais duas usinas hidrelétricas (UHE) no rio Madeira, a montante da cidade de Porto Velho, Rondônia, Brasil (de Santo Antônio e Jirau). O objetivo deste trabalho foi analisar a prevalência da malária antes do início da implantação das obras civis e fazer considerações sobre os impactos da doença com o ingresso de milhares de trabalhadores e agregados atraídos pelas oportunidades de emprego e comércio. Os resultados obtidos mostram que a malária se faz presente em toda região, em variados graus de prevalência. Além disso, a existência de potenciais portadores assintomáticos de malária entre a população nativa pode ter relevância epidemiológica e deve ser considerada nos programas de controle da malária, vinda tanto das autoridades públicas quanto das empresas responsáveis pela instalação das UHE, visando o diagnóstico e tratamento precoce, controle vetorial, abastecimento de água e aplicação de infra-estrutura nos centros urbanos.

In Rondônia State, Brazil, two new hydroelectric plants, Santo Antônio and Jirau, are scheduled for construction on the Madeira River, upriver from the State capital, Porto Velho. The current study analyzes malaria prevalence before the construction and provides information on the possible impacts of malaria burden related to the influx of thousands of persons attracted by direct and indirect employment opportunities. According to the findings, malaria is present throughout the region, with varying prevalence rates. The existence of potential asymptomatic malaria carriers among the local population may be epidemiologically relevant and should be considered in the malaria control programs organized by public authorities and companies responsible for building the power plants, aimed at early diagnosis and treatment, vector control, water supply, and infrastructure in the urban areas.

Em Rondônia, prevê-se a construção de mais duas usinas hidrelétricas (UHE) no rio Madeira, a montante da cidade de Porto Velho, Rondônia, Brasil (de Santo Antônio e Jirau). O objetivo deste trabalho foi analisar a prevalência da malária antes do início da implantação das obras civis e fazer considerações sobre os impactos da doença com o ingresso de milhares de trabalhadores e agregados atraídos pelas oportunidades de emprego e comércio. Os resultados obtidos mostram que a malária se faz presente em toda região, em variados graus de prevalência. Além disso, a existência de potenciais portadores assintomáticos de malária entre a população nativa pode ter relevância epidemiológica e deve ser considerada nos programas de controle da malária, vinda tanto das autoridades públicas quanto das empresas responsáveis pela instalação das UHE, visando o diagnóstico e tratamento precoce, controle vetorial, abastecimento de água e aplicação de infra-estrutura nos centros urbanos.

In Rondônia State, Brazil, two new hydroelectric plants, Santo Antônio and Jirau, are scheduled for construction on the Madeira River, upriver from the State capital, Porto Velho. The current study analyzes malaria prevalence before the construction and provides information on the possible impacts of malaria burden related to the influx of thousands of persons attracted by direct and indirect employment opportunities. According to the findings, malaria is present throughout the region, with varying prevalence rates. The existence of potential asymptomatic malaria carriers among the local population may be epidemiologically relevant and should be considered in the malaria control programs organized by public authorities and companies responsible for building the power plants, aimed at early diagnosis and treatment, vector control, water supply, and infrastructure in the urban areas.

Após fazer uma análise da evolução da malária na Amazônia brasileira, detalhando em particular a situação em Rondônia e no município de Porto Velho, onde ocorreram episódios dramáticos de epidemias de malária no passado, os autores apresentam o quadro atual da prevalência de malária nas áreas do Vale do Rio Madeira, que sofrerão impactos com a construção das hidrelétricas de Santo Antônio e Jirau, e alertam sobre a situação particular da malária em áreas ribeirinhas. Nessas áreas, observam-se alta incidência de malária vivax e falciparum, a presença de grande número de portadores assintomáticos de parasitas e altas densidades do vetor Anopheles darlingi o ano todo. Esses elementos, associados à provável chegada de migrantes oriundos de áreas não-endêmicas de Rondônia e de outros Estados do país, atraídos pela possibilidade de trabalho nessas hidrelétricas e oportunidades de comércio, lazer, educação e atividades domésticas, criam condições favoráveis à ocorrência de epidemias de malária e de outras doenças tropicais se não forem realizadas intervenções adequadas de controle, em particular no domínio do saneamento.

The authors present a short review on the evolution of malaria incidence in the Brazilian Amazon, with particular reference to the Rondônia State and the Municipality of Porto Velho, where dramatic epidemics of malaria and other tropical diseases have been registered in the past. Next, they analyze the present endemic malaria situation in the Madeira River Valley where two important Hydroelectric Power Plants will be constructed in the localities of Santo Antônio and Jirau. Longitudinal surveys performed in the last four years in this area allow to demonstrate a high prevalence of symptomatic and asymptomatic malaria carriers in the area, associated to the presence of high densities of the malaria vector Anopheles darlingi all over the year. These elements are correlated to the expected arrival of a large number of human migrants originated from non endemic areas of Rondônia and other Brazilian States, attracted by the possibility of jobs in the Hydroelectric Power Plants and by secondary opportunities in commerce, leisure, education and domestic activities. These associations create favorable conditions for malaria outbreaks and other tropical diseases that must be avoided by the establishment of additional control measures, in particular in the sanitation domain

A primeira epidemia de febre do dengue no Estado de Rondônia, Região Ocidental do Brasil foi registrado em 1997, sem confirmação laboratorial. Em seguida, houve uma epidemia descrita em 1998, em Manaus, no vizinho Estado do Amazonas, onde os vírus DENV-1 e DENV-2 foram isolados de pacientes. No presente artigo, foi descrito a caracterização do sorotipo do vírus dengue isolado de pacientes com suspeitas clinicas de dengue em Porto Velho, Rondônia, entre 2001 a 2003. Foram coletadas 150 amostras de sangue, entre primeiro e quinto dia de sintomas. Setenta amostras de vírus isolados foram submetidas a identificação do dengue pela RT-PCR usando primers universais para gene da NS1 do DENV que amplifica um fragmento de 419pb. O amplicon obtidos foram submetidos a digestão enzimática para caracterização do sorotipo viral. Todas as amostras analisadas foram DENV-1. A seqüência nucleotídica de um dos amplicons aleatoriamente selecionada também DENV-1 demonstrou 98% similaridade com as seqüências do Sudeste Asiático obtidas no GenBank.

The first dengue fever epidemic in the State of Rondônia (western region of Brazil) was recorded in 1997, without laboratory confirmation. Following this, there was an epidemic in Manaus, in the neighboring State of Amazon, in 1998, in which DENV-1 and DENV-2 viruses were isolated from patients. In the present paper, the serotype characterization of the dengue virus isolated from patients with clinically suspected dengue in Porto Velho, Rondônia, between 2001 and 2003 is described. One hundred and fifty blood samples were collected between the first and fifth days of symptoms. Seventy samples of virus isolates were subjected to dengue identification by means of RT-PCR using universal primers for the NS1 gene of DENV, which amplifies a 419 bp fragment. The amplicons obtained were subjected to enzymatic digestion to characterize the viral serotypes. All the samples analyzed were DENV-1. A nucleotide sequence randomly selected from one amplicon, which was also DENV-1, presented 98% similarity to sequences from Southeast Asia that were obtained from GenBank.

Cross sectional studies on malaria prevalence was performed in 2001, 2002, and 2004 in Vila Candelária, an urban riverside area of Porto Velho, Rondônia, in the Brazilian Western Amazon, followed by longitudinal surveys on malaria incidence. Vila Candelária is a working class district, provided with electricity, water supply, and basic sanitation. Previous preliminary surveys indicated high malaria incidence in this community. At the end of year 2000 regular diagnostic and treatment measures for malaria were introduced, with active search of febrile cases among residents. Despite of both rapid treatment of cases and relative good sanitary and housing conditions, the malaria incidence persisted at high levels during the following years with an annual parasite index of 150 to 300/1000 inhabitants. Parasite surveys in 2001, 2002, and 2004 achieved through microscopy and polymerase chain reaction to diagnose malaria showed a constant high prevalence of asymptomatic carriers for both Plasmodium falciparum and P. vivax parasites. It was concluded that asymptomatic carriers represent an important reservoirs of parasites and that the carriers might contribute to maintaining the high level of transmission. Comparing our findings to similar geo-demographic situations found in other important urban communities of the Brazilian Amazon, we propose that asymptomatic carriers could explain malaria's outbreaks like the one recently observed in Manaus.

Longitudinal entomological surveys were performed in Vila Candelária and adjacent rural locality of Bate Estaca concomitantly with a clinical epidemiologic malaria survey. Vila Candelária is a riverside periurban neighborhood of Porto Velho, capital of the state of Rondônia in the Brazilian Amazon. High anopheline densities were found accompanying the peak of rainfall, as reported in rural areas of the region. Moreover, several minor peaks of anophelines were recorded between the end of the dry season and the beginning of the next rainy season. These secondary peaks were related to permanent anopheline breeding sites resulting from human activities. Malaria transmission is, therefore, observed all over the year. In Vila Candelária, the risk of malaria infection both indoors and outdoors was calculated as being 2 and 10/infecting bites per year per inhabitant respectively. Urban malaria in riverside areas was associated with two factors: (1) high prevalence of asymptomatic carriers in a stable human population and (2) high anopheline densities related to human environmental changes. This association is probably found in other Amazonian urban and suburban communities. The implementation of control measures should include environmental sanitation and better characterization of the role of asymptomatic carriers in malaria transmission.

Em uma área de alta transmissão de malária (Costa Marques, Rondônia) foi feito um estudo para determinar a prevalência de parasitemia assintomática e seu significado clínico. A maioria dos habitantes estudados era imigrante que vivia na região há menos de 5 anos. Em Costa Marques há facilidades para o diagnóstico e pronto tratamento da malária. Em 344 pessoas examinadas havia 77 (22%) com parasitemia para hematozoários. Entre estes, 36 não tinham sintomatologia de malária. Após dois dias, 19 dos 36 desenvolveram sintomatologia. Dos 17 que continuavam assintomáticos, 4 tinham somente gametócitos no esfregaço de sangue examinado, 1 tinha recebido tratamento antimalárico inadequado, 3 estavam em tratamento e 2 se mudaram da área. Entre o 3.º e 6.º dia 6 apresentaram sintomatologia. Um paciente continuou assintomático no 7.º dia, quando terminou a observação. Ele contava já ter tido mais de 40 ataques de malária. Exceto ele, todos os outros assintomáticos ou estavam no período de incubação ou em tratamento. Conclui-se que a malária assintomática é rara em Costa Marques e que é necessário tratar todos os indivíduos com parasitemia.

A malaria survey was conducted in an area of high transmission (Costa Marques, Rondonia, Brazil) to determine the prevalence of asymptomatic parasitemia and its clinical significance. Most of the people surveyed were immigrants who had lived in the endemic area < 5 years. The people had easy access to free diagnostic and treatment services at the Malaria Clinic in the town of Costa Marques. The prevalence of plasmodial parasitemia in 344 people was 22%. There were 36 individuals with asymptomatic infections among the 77 parasitemic patients. During the two days following the initial examination, 19 ofthe 36 individuals: with asymptomatic infections developed malaria. Among the 17 patients who remained asymptomatic for > 2 days, 4 had only gametocytes, 1 had taken inadequate anti-malarial treatment, 3 were under treatment and 2 moved. Six asymptomatic patients denied the use of anti-malarial drugs and they developed malaria 3-6 days after the initial parasitological diagnosis. The final patient remained asymptomatic during the 7 day observation period. He had a history of > 40 malaria attacks and denied the use of antimalarial treatment. With the exception of the latter all of the other asymptomatic patients, were either in the incubation period or had been treated It is concluded that asymptomatic malaria is rare in the Costa Marques area and that it is necessary to treat all individuals with plasmodial parasitemia.