Filarial infections (lymphatic filariasis and onchocerciasis) are amongst the major neglected tropical diseases, and together account for more than 120 million infections in tropical and subtropical regions. The gold-standard technique for the diagnosis of filariases relies on the detection of microfilariae (mf) either in blood smears (lymphatic filariasis) or in skin biopsies (onchocerciasis). The secretion of extracellular RNAs (exRNAs) by parasitic nematodes has opened new avenues for the development of novel biomarkers for helminthiases, including filariasis. However, rather little is known about the origin and regulation of these RNAs inside the nematodes. One outstanding question is whether the secretion of small RNAs is distinct across the developmental stages of parasitic nematodes. Similarly, it is not clear whether the secretion of miRNAs is affected by treatment with anthelminthic chemotherapy or their potential as biomarkers for infection. Litomosoides sigmodontis is a murine filarial nematode closely related to filarial nematodes of medical and veterinary importance, including Onchocerca spp. and Brugia spp. L. sigmodontis has been extensively used to decipher multiple aspects of filarial biology, including parasite development, vaccine, and host-pathogen interactions. Therefore, we decided to use this model to address fundamental questions regarding the secretion of small RNAs and their biomarker potential. Our in vitro studies demonstrate that some extracellular miRNAs are enriched in a sexand stage-specific manner in the Excretion/Secretion (ES) products from early larval and adult stages from the rodent filarial nematode Litomosoides sigmodontis. Moreover, our data demonstrates that the gravid adult female worms secrete a plethora of miRNAs enriched in the secretome of this developmental stage when compared to adult males or mf. Further characterization studies show that the miRNAs are likely to be secreted in association with extracellular vesicles (EVs), as previously reported for other parasitic nematodes, including the human pathogen Brugia malayi. Interestingly, Ivermectin, which is typically used to treat filarial infections, does not have consistent effects on the secretion of miRNAs by gravid adult female worms in vitro, requiring further in vivo experiments to determine the effect of IVM on detection of extracellular parasite-derived miRNAs. In vivo experiments, using murine models of infection with L. sigmodontis (gerbils and BALB/c mice), as well as human samples from patients infected with Onchocerca volvulus and cattle infected with Onchocerca ochengi, demonstrated the presence of filarial-derived miRNAs, including female-specific miRNA markers, in biofluids from infected hosts. Further statistical analysis showed that two parasite-derived miRNAs, miR-71 and miR-100d, can significantly discriminate infected animals from naïve controls with high sensitivity/specificity (> 80%/100%). The results presented in this PhD thesis provide an initial framework to understand the secretion of small RNAs throughout nematode development, the potential interactions between anthelminthic chemotherapy and small RNA trafficking and secretion, as well as the use of parasite-derived miRNAs for the development of a new generation of biomarkers for filarial infections.

Made available in DSpace on 2012-05-07T14:43:57Z (GMT). No. of bitstreams: 2 license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) 000062.pdf: 2830403 bytes, checksum: 89eae1ce6eb7f974bdf91fade797ad15 (MD5) Previous issue date: 2008 / A filariose linfática continua a ser um sério problema de saúde pública. Segundo a Organização Mundial da Saúde existem aproximadamente 16 milhões de casos de linfedema e cerca de 27 milhões de homens com manifestações urogenitais. Uma alternativa para delimitação de áreas endêmicas foi validada na África e na Índia com abordagem da morbidade filarial pelos informantes-chave. No Brasil, em base populacional, poucas informações são disponíveis acerca da morbidade filarial, encontrando-se apenas relatos isolados acerca da ocorrência de manifestações da doença. Este estudo propõe avaliar a correlação entre a prevalência da morbidade filarial referida e a ocorrência de microfilaremia, por bairro, no município de Jaboatão dos Guararapes/PE, no período de 2001/2002, utilizando-se um estudo ecológico, em duas etapas: exploratória e analítica. Estimou-se uma prevalência de 6 por cento de domicílios positivos para filariose, sendo pesquisados 6.507 residências, investigando-se 23.673 pessoas, distribuídas em três Distritos. A pesquisa de microfilária de Wuchereria bancrofti foi feita pela técnica de gota espessa, coletada entre 23H00 e 01H00. As informações das manifestações clínicas relativas à parasitose foram obtidas através de questionário aplicado pelos Agentes Comunitários de Saúde e Agentes de Combate à Filariose, previamente treinados e capacitados na identificação e conhecimento da doença. Para análise de correlação foram utilizados o Coeficiente de Correlação de Pearson (r= regressão linear simples) e o teste de significância estatística correspondente. A prevalência de infecção filarial foi de 1,4 por cento e a da morbidade referida foi de 3,1 por cento, ambas ocorrendo com maior freqüência no bairro de Cavaleiro. Neste estudo observou-se uma associação positiva entre a prevalência das queixas filariais e a prevalência da microfilaremia, analisadas por bairro. A hidrocele foi a manifestação referida que se destacou, apresentando a associação mais fortemente positiva (r=0,699; p0,001), resultado, até então, evidenciado em áreas de alta endemicidade. Este achado indica que esta condição clínica tem valor preditivo positivo para o risco de filariose linfática, mesmo em áreas de baixa prevalência da parasitose.

Made available in DSpace on 2012-09-05T18:24:08Z (GMT). No. of bitstreams: 2 license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) 276.pdf: 1326782 bytes, checksum: bae32ec1487817e0d1342725c58ded5e (MD5) Previous issue date: 2006 / A filariose linfática bancroftiana é uma doença parasitária humana de grande complexidade em sua dinâmica de infecção, necessitando ainda de maiores esclarecimentos, principalmente, em aspectos relacionados à tolerância e imunopatologia. A existência da imunidade protetora em comunidades endêmicas de filariose permanece como objeto de intenso debate e o grupo denominado endêmicos normais , tem sido alvo de interesse para elucidar muitas questões referentes à imunologia da doença. O presente trabalho tem como objetivo verificar através de um estudo do tipo caso-controle, as diferenças entre portadores e não portadores de filariose linfática bancroftiana pelo reconhecimento humoral de bandas protéicas de extrato secretório-excretório de larvas infectantes de Wuchereria bancrofti. Os quatro setores censitários de Olinda-PE, com maior prevalência de filariose, foram escolhidos como área de estudo. Consideramos grupo controle portadores da filariose bancroftiana e grupo de casos os de endêmicos normais. (...) A identificação desse grupo de proteínas respondedoras em endêmicos normais deve nortear novas pesquisas para o estudo bioquímico desses compostos e sua relação com a imunidade protetora em filariose linfática bancroftiana.

No description available.

Brugia malayi is one of the causative agents of the disabling and disfiguring disease known as Lymphatic Filariasis (LF). This infection is a well-established ailment in tropical and subtropical countries and recently the drug ivermectin has been introduced for the LF control programs. Ivermectin (IVM) is an excellent microfilaricide, but is not markedly macrofilaricidal. However, it causes a long-lasting reduction in the production of new larvae by female worms, suggesting that adult stages are affected. However, the mechanism by which IVM produces such effect in the adult worm is not well understood. One major reason is our incomplete understanding about the biological effect of IVM on adult stages. The present study was carried out to examine the in vitro effects of IVM on B. malayi adult worms using Brugia-gerbil animal model. And also to have some leads in understanding the drug-uptake and location of probable targets in the worm body by using fluorescent labeled IVM and confocal microscopy. / The antifilarial effects of IVM were examined using three parameters: mf release by female worms, and motility, and viability in both male and female worms. The results reported in this study demonstrate that although IVM did not kill the adult worm, but showed significant antifilarial effects on B. malayi adult stages when examined in an in vitro system. Confocal microscopy images of the worms incubated in bodipy FITC-IVM showed strong specific localization signal in the anterior cephalic region of both male and female worms. These observations suggest the early/initial interactions of the drug with its probable receptors that could be located specifically in the head region.

A current initiative to eliminate lymphatic filariasis (LF), headed by the World Health Organization, aims to interrupt transmission of the disease through yearly community-wide treatment with the broad spectrum anthelmintic albendazole (ABZ), in combination with ivermectin (IVM) or diethylcarbamazine (DEC). Over the years, the use of both ABZ and IVM in the treatment of veterinary parasites has led to widespread anthelmintic resistance against these drugs. In this study, we genotyped microfilaria of Wuchereria bancrofti, a causative agent of LF, in order to detect the presence of mutations which confer ABZ resistance in other parasites, and we identified such mutations in worms obtained from untreated patients in Ghana and Burkina Faso, West Africa. Microfilaria from patients who had been treated with ABZ + IVM, had a significantly higher frequency of the resistant genotype, and this frequency was even higher in worms from patients that had received two rounds of treatment. In addition, the untreated population of microfilaria had an excess of homozygotes in the population. This excess homozygosity was equivalent to a Wright's Inbreeding Statistic of FIT= 0.44, and we found that the population was significantly subdivided between patients. In order to better understand the mechanisms and factors involved in the potential spread of ABZ resistance, caused by such mutations, through a population of Culex-transmitted W. bancrofti, we developed a deterministic model that incorporates genotype structure into the epidemiological model EPIFIL. This model predicts that the combination of ABZ + DEC leads to stronger selection for the resistant genotype than ABZ + IVM, and that drug efficacy assumptions are an important factor affecting the spread of drug resistance. Treatment coverage, non-random mating, initial allele frequency and number of treatments also had substantial impact on the speed and magnitude of the spread of ABZ resistance. When we expanded this model to include potential IVM-resistance alleles we found that, under ABZ + IVM treatment, selection for resistance to either drug is enhanced by the presence of resistance against the second drug. Similarly, excess homozygosity caused by parasite non-random mating may increase selection for a dominant IVM resistance allele through enhancing the spread of a recessive ABZ resistance allele. Resistence developed more slowly when it was inherited as a polygenic trait. Results from this study suggest that resistance monitoring is crucial, as resistance may not be apparent until treatment is stopped, recrudescence occurs and treatment is reapplied.

No description available.

Mestre -- Escola Nacional de Saude Publica, Rio de Janeiro, 2002.

Made available in DSpace on 2016-04-12T12:32:34Z (GMT). No. of bitstreams: 2 562.pdf: 1277305 bytes, checksum: f0ab3ef05319cffcb6fcae1ecd252dc0 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2010 / Fundação Oswaldo Cruz. Centro de Pesquisas Aggeu Magalhães. Recife, PE, Brasil / A filariose bancroftiana é uma parasitose que causa incapacidade momentânea ou permanente e estigmatizarão social trazendo sobrecarga para os recursos da saúde. No Brasil, são duas áreas endêmicas: Região Metropolitana do Recife (PE) e Maceió (AL). Em 1997, o Ministério da Saúde elaborou o Plano Nacional de Eliminação da Filariose Linfática - PNEFL cujos pilares foram o Tratamento em Massa ou Coletivo - TC, o controle do vetor e a assistência aos portadores da infecção. Essas ações, porem, não incorporam o conhecimento e as praticas da população sobre o problema, impossibilitando a mobilização social como ação básica e transversal para todas as etapas acima de intervenção. Este estudo aborda a analise dos conhecimentos e praticas em portadores de morbidade filarial linfática em dois bairros (Alto da Bondade e Alto da Conquista) de Olinda-PE, Brasil. Trata-se de estudo transversal de base populacional com coleta de dados primários obtidos por meio da aplicação de questionário semi-estruturado. A associação estatística entre as variáveis foi testada pelo calculo do quiquadrado de Pearson, e o valor p, a um nível de significância de 0,05. Os 373 portadores de morbidade filarial referida identificados entre 2007 a 2010 apresentaram um bom conhecimento com relação à transmissão da filariose linfática e conhecimento insuficiente com relação ao diagnostico. Com relação ao tratamento, 222/373 não sabiam tratar a doença e dentre os que souberam 151/373 (40,5 por cento) apresentaram conhecimento adequado. Com relação à cura, 255/373 (68,4 por cento) apresentaram conhecimento adequado e 187/373 (50,1 por cento) buscaram o serviço de saúde onde 95 por cento desses foram tratados por médicos. A maioria da população dos dois bairros do município evitava a picada do mosquito mediante o uso de mosquiteiros. Foi verificada a necessidade de melhor incentivo e divulgação para as praticas de cuidado com o lixo e entulhos. Conclui-se que o conhecimento e praticas em Filariose Linfática em áreas endêmicas apresentam diferentes concepções, saberes e praticas acerca da doença, inferindo que essas diferenças precisam ser estudadas pelo serviço de saúde informando ao gestor o que a população sabe e faz para prevenir a filariose linfática, permitindo intervenção nas estratégias de informação, educação e comunicação, auxiliando no controle e eliminação da doença no município.

Filarial parasites are a type of nematode that requires arthropod vectors for transmission between hosts. Filarial parasites vary among species of vertebrate hosts and can cause varying symptoms in hosts, including death. The presence of filarial parasites can influence host populations and can be costly to infected areas. To evaluate the prevalence of filarial parasites in Lake County, CA, mosquitoes were collected in 2014 and analyzed for infection using polymerase chain reaction (PCR). Of 1,008 mosquito pools, six filarial parasite species were detected in 23 pools representing six mosquito species. The DNA of Dirofilaria immitis (n=6, MIR=0.26); Setaria yehi (n=9, MIR=1.44); Splendidofilaria sp. (n=4, MIR=0.20); unknown filarial parasites A (n=2, MIR=0.09), B (n=1, MIR=0.41), and C (n=1, MIR=0.05) were detected in Aedes increpitus, Aedes sierrensis, Anopheles franciscanus, Anopheles freeborni, Culex stigmatosoma, and Culex tarsalis mosquito pools. Due to the presence of D. immitis, which can lead to chronic illness and death in domestic dogs, in Lake County it is important to evaluate vector competency of D. immitis in mosquito species. Culex tarsalis was chosen due to the high abundance found in Lake County in 2014 (n=36,587). To evaluate vector competency of Cx. tarsalis in transmission of D. immitis, colony and field-caught Lake County (n=102, n=54 respectively) mosquitoes were analyzed for infectivity using decapitation. Fourteen days post feeding on infected blood, mosquitoes were decapitated to evaluate the presence of L 3 larvae; but no L 3 larvae were detected. The presence of D. immitis DNA was detected in eight colony (IR=7.8%) and fifteen field-caught (IR=23.1%) thoraces using PCR. Though no L 3 larvae were observed in decapitated mosquitoes, presence of D. immitis DNA in the thoraces of mosquitoes using PCR has previously been used as an indicator for vector competency. Thus it is probable that Cx. tarsalis is a competent vector for D. immitis.