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Investigation of the occurrence of bancroftian filariasis in Porto Velho, Rondônia, Brazil

Grant number: 07/00848-9
Support Opportunities:Regular Research Grants
Duration: February 01, 2008 - January 31, 2010
Field of knowledge:Health Sciences - Medicine
Principal Investigator:Luís Marcelo Aranha Camargo
Grantee:Luís Marcelo Aranha Camargo
Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Associated researchers: Ana Rachel Vasconcelos de Lima ; Anderson Brandão Leite ; Caroline dos Anjos ; Cledson de Lima Mercês Júnior ; Eliana Maria Mauricio da Rocha ; Francisco Neudo Rebouças Chaves ; Gilberto Fontes ; Guilherme Angelo Vilela Faria ; Juliana de Souza Almeida Aranha Camargo ; Kaluan de Oliveira Costa ; Luana Janaína Souza Vera ; Paulo Henrique Bonassa


Filariasis comprehends a group of diseases associated to helminthes of the phylum Nematode, Filarioidea superfamify. In Brazil, we can find parasites such as Wuchereria bancrofti, Onchocerca volvulus and Mansonella ozzardi that are human parasites that cause many clinical forms of the disease.The former is transmitted by Diptera of the Culex genus and the others are transmitted by Simulidae ("black fly") and Ceratopogonidae("midges").Onchocerca volvulus and Mansonella ozzardi frequenty occur on the margins of rivers while Wuchereria bancrofti, the subject of this paper, occurs in the urban areas. Cases of this disease have been registered in Manaus, Belém,Recife, Maceió, Salvador and Porto Velho (non autochthonous), among other Brazilian cities (Rachou, 1960).Wuchereria bancrofti, that causes lymphatic filariasis, is endemic in many tropical and semi-tropical regions around the world.It is estimated that approximately 800 million people live in 83 countries in areas where they risk to be infected. In fact, 106 million have already been infected by W. bancrofti (WHO, 2000). This disease has been neglected and predominates among poor populations where sanitation and water treatment is practically non existent.Due to its precarious urbanization, the existence of potential vectors and its similarities with other Amazonian cities that have presented Bancrofilariasis in the past, it is possible that this helminthosis is also present in the capital of Rondônia. Methodology Area where the study will be conducted: peripheral districts of Porto Velho, on the margin of the Madeira River (Baixa da União, Nacional and Belmont). A geographical mapping of the area will be conducted and the size of the sample will be calculated after the mapping of the above mentioned districts is concluded. The sample unit will be he domicile; 1% empiric prevalence, 20% sample loss, error 5% and power 80%, calculated by the EpiInfo 6.01 program. Estimate of Human Microfilaremia PrevalenceBlood samples will be collected twice a week between 10:00 pm and 1 am, at the patients' domiciles. The thick smear method will be used according to standard technique. After the process, the samples will be packed and sent to the Federal University of Alagoas. At the UFAL, a blood GE will be stained. The slide will be examined on an optic microscope, with a 10X and 40Xsystem of lenses. Capture and Identification of Vectors and W.bancrofti larvae research and Insect capture: ingurgitated insects will be captured (xenomonitoring) inside domiciles randomly selected in specific areas (from 8:00 am to 1:am). The insects will be placed in thin mesh cages, separated according to the place and date of capture and then taken to the laboratory to be examined.Entomological Classification and insect separation: Captured Culex quinquefasciatus females will be examined because they are W. bancrofti vectors. The separated insects will be placed in tubes and frozen at -20oC for posterior PCR examination.Porimerase Chain Reaction (PCR): The system of detection to be utilized is the PCR amplification of a repetitive genomic fragment of W. bancrofti, a sequence denominated Sspl of 188bp (Zhong et al. 1006). The technical procedure was previously standardized according to our conditions, the DNA being extracted according to the method described by VASUKI et al. (2003).Analysis and data validation: Because the PCR is not quantitative, it will not be possible to estimate how many W. bancrofti larvae, in their respective stages of development, are present in each sample of examined mosquitoes. However, the prevalence of vectorial infection will be estimated with the aid of the "Poolscreen" program (KATHOLI et al., (2003). The xenomonitoring validation will be conducted comparing the results obtained with the antigenemia and microfilaremia data of the individuals living at the endemic area studied. (AU)

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Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
RODOLFO LUÍS KORTE; GILBERTO FONTES; JULIANA DE SOUZA ALMEIDA ARANHA CAMARGO; ELIANA MARIA MAURÍCIO DA ROCHA; EDICARLOS ANDRÉ CAVALCANTE DE ARAÚJO; MARCELO ZAGONEL DE OLIVEIRA; RAFAEL VITAL DOS SANTOS; LUÍS MARCELO ARANHA CAMARGO. Survey of Bancroftian filariasis infection in humans and Culex mosquitoes in the western Brazilian Amazon region: implications for transmission and control. Revista da Sociedade Brasileira de Medicina Tropical, v. 46, n. 2, p. 214-220, . (07/00848-9)

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