Polymerase chain reaction for the evaluation of Schistosoma mansoni infection in two low endemicity areas of Minas Gerais, Brazil

This study aimed to evaluate the occurrence of schistosomiasis in areas with low endemicity using polymerase chain reaction (PCR) as a diagnostic method. We analysed faecal samples from 219 individuals residing in Piau and Coronel Pacheco, state of Minas Gerais, Brazil, using a single faecal sample from each individual and two slides of the Kato-Katz technique as a gold standard. Fifteen out of the 219 samples were positive with both methods of diagnosis. One sample was diagnosed as positive by the Kato-Katz technique only and 61 were diagnosed only by PCR. The positivity rates were 7.3% with the Kato-Katz method and 34.7% with PCR. When both techniques were assumed to have 100% specificity and positive individuals were identified by both methods, the sensitivity of the Kato-Katz method was 20.8% and the PCR sensitivity was 98.7%. The Kappa index between the two techniques was 0.234, suggesting weak agreement. The assessment of a single faecal sample by PCR detected more cases of infection than the analysis of one sample with two slides using the Kato-Katz technique, suggesting that PCR can be a useful diagnostic tool, particularly in areas with low endemicity.

Essential oil from leaves of Lantana camara: a potential source of medicine against leishmaniasis

Leishmaniasis is an infection of viscera or tegument caused by protozoa Leishmania sp. The extensive period required for the treatment, which involves the use of toxic medicines, leads patients to drop treatment increasing the development of resistant forms of Leishmania sp. Lantana camara L., Verbenaceae, is a tropical plant native from America. Folk uses have been described for treatment of tumors, tetanus, rheumatism and malaria. This study evaluates the leishmanicidal activity of the essential oil of leaves from L. camara on promastigote forms of Leishmania chagasi and L. amazonensis and its toxic effects on Artemia salina (brine shrimp test), macrophage cultures and BALB/c mice. The chemical composition was evaluated using the gas chromatography coupled with mass spectrometer (GC-MS). Thirty substances, mostly mono and sesquiterpenes were identified. The most representative constituents were: germacrene D (24.90%), farnesene derivatives (22%) and (E)-cariophylene (14.31%). Bioassays revealed a significant leishmanicidal activity of essential oil against L. amazonensis (IC50 0.25 µg/ mL) and a potential toxic effect on Brine shrimp (LC50 10 µg/mL) and macrophage assays (CC50 4 µg/mL), while there was no toxic manifestation on mice. The data show the relevant potential of L. camara as a source of medicine for leishmaniasis treatment.

Prevalência de parasitoses intestinais em comunidade quilombola no município de Bias Fortes, estado de Minas Gerais, Brasil, 2008 / Prevalence of parasitic intestinal diseases in a quilombola community, in the Municipality of Bias Fortes, State of Minas Gerais, Brazil, 2008

Objetivo: investigar a prevalência e os fatores associados às parasitoses intestinais na população de Colônia do Paiol, comunidade quilombola na Zona da Mata de Minas Gerais, Brasil. Metodologia: procedeu-se um estudo de corte transversal por censo, sendo que dos 425 moradores, 391 (92 por cento) foram avaliados mediante resposta a questionário estruturado e exame coproparasitológico. Resultados: a positividade para pelo menos uma espécie parasitária foi de 63,8 por cento, sendo as espécies patogênicas mais frequentes Ascaris lumbricoides (22,4 por cento) e Trichuris trichiura (17,9 por cento); o poliparasitismo ocorreu em 36,5 por cento dos investigados; predominaram casos no sexo feminino e na faixa etária de escolares de seis a 14 anos de idade. Conclusão: observou-se associação entre a presença de parasitos intestinais e determinadas condições ambientais, confirmando a necessidade de melhoria das condições de saneamento básico e de acesso ao serviço de saúde, de utilização de medicações de fácil administração no tratamento das enteroparasitoses e de educação em saúde para os membros da comunidade.

Objective: the study aims to investigate prevalence and factors associated to intestinal parasitic diseases in the population of Colônia do Paiol, a quilombola community in the municipality of Bias Fortes, located in the Zona da Mata region of the State of Minas Gerais, Brazil. Methodology: cross-sectional census study was conducted, and 391 (92 per cent) of the 425 inhabitants were interviewed through a questionnaire and evaluated by means of a coproparasitologic test. Results: the test positivity rate for at least one parasite specie was of 63.8 per cent, and the pathogenic species more often found were Ascaris lumbricoides (22.4 per cent) and Trichuris trichiura (17.9 per cent); multiparasitism was diagnosed in 36.5 per cent of those who took part in the study; prevalence was higher for females compared to males, also for school children aged from 6 to 14 years old. Conclusion: a significant association was observed between the presence of intestine parasites and a number of environment conditions such as sewage collection and disposal, access to basic health services, use of easily administered medicines for treatment of enteroparasitosis, and education policies on basic health knowledgeamong population members.

Anti-mycobacterial treatment reduces high plasma levels of CXC-chemokines detected in active tuberculosis by cytometric bead array

Chemokines recruit and activate leukocytes, assisting granuloma formation. Herein, we evaluated plasma chemokines in patients with active tuberculosis (ATB) and after completing treatment (TTB) and compared them to BCG-vaccinated healthy controls (HC). Levels of chemokines were measured by cytometric bead array. Levels of CXCL8, CXCL9 and CXCL10 were higher in ATB patients compared to HC, but they decreased in TTB. Levels of CCL2 and CCL5 in ATB patients were similar to those observed in HC. Thus, the high levels of CXC-chemokines detected during ATB, which can modulate the trafficking of immune cells from the periphery to the site of infection, were reversed by anti-mycobacterial treatment.

Validação do número de lâminas para realização do método de sedimentação espontânea das fezes / Validation of the number of slides for accomplishment of the faecal spontaneous sedimentation method

Este estudo avaliou o número satisfatório de lâminas a serem examinadas pela técnica de sedimentação espontânea das fezes ou de Hoffmann, Pons e Janer (HPJ), com o intuito de contribuir para a eficiência no diagnóstico de exames coproparasitológicos no diagnóstico de parasitoses, objetivando menor custo e maior benefício. A partir de um estudo da prevalência de enteroparasitoses, cujo cálculo amostral aleatório teve como base toda a população residente no município de Piau -Minas Gerais, foram investigadas 925 amostras. O número máximo de lâminas examinadas para cada amostra de fezes foi de cinco, considerado como padrão-ouro. Cada lâmina foi avaliada por cinco examinadores diferentes. Na análise de apenas uma lâmina, a frequência de positividade para enteroparasitos foi inferior a 60% e aumentou para 79,7% na análise de uma segunda lâmina. Na observação da terceira e quarta lâminas, a positividade das amostras foi 87,5% e 95,3%, respectivamente. Verificou-se que a sensibilidade e especificidade aumentaram com o número de lâminas examinadas e que na observação de três lâminas por amostra, a sensibilidade foi de 87,5% e a especificidade de 99,1%. Entre os enteroparasitos, os ancilostomídeos e Giardia lamblia foram os mais prevalentes, representando 13,7% de positividade para ambos. A análise de apenas uma lâmina por amostra elevou o risco de resultado falso negativo. Os resultados encontrados sugerem a realização de três lâminas por amostra pela técnica do HPJ na tentativa de aumentar a acurácia do método diagnóstico com custos sustentáveis para a gestão junto ao Sistema Único de Saúde.

This work analyzed the optimal number of slides necessary in the spontaneous fecal sedimentation method, also known as the Hoffmann, Pons e Janer (HPJ) technique, with the objective of increasing efficiency and reducing cost of the diagnosis of parasitic infections using the stool test. In a study of the prevalence of intestinal parasite infection in a random sampling of the resident population of Piau, Minas Gerais, 925 samples were analyzed. The maximum number of slides analyzed for each fecal sample was five, considered as the gold standard. Each slide was evaluated by five different analysts. Upon examination of only one slide, the positive frequency for enteroparasites was less than 60.0% and increased to 79.7% when analyzing a second slide. After analysis of a third and fourth slide, the number of enteroparasite positive samples increased to 87.5% and 95.3%, respectively. It was verified that the sensitivity and specificity increased with the number of slides examined and, after observation of three slides per stool sample, the sensitivity was 87.5% and the specificity was 99.1%. Among the enteroparasites detected, the most prevalent were hookworms and Giardia lamblia, with a frequency of 13.7% for both. The analysis of only one slide per sample increased the risk of false negative result. The findings suggest that the examination of three slides per stool sample using the HPJ fecal spontaneous sedimentation technique is optimal in order to increase the efficiency of the fecal diagnostic method without substantially increasing costs for the public health care system.

Diagnóstico imunológico da tuberculose: problemas e estratégias para o sucesso / Immunological diagnosis of tuberculosis: problems and strategies for success

A tuberculose continua sendo um grave problema social e de saúde, afetando milhões de pessoas anualmente. A vacina Bacille Calmette-Guerin (BCG), usada no controle profilático, é incapaz de conter a progressão da doença, que usualmente se manifesta através da queda da imunidade celular do indivíduo. O diagnóstico da tuberculose em seus estágios iniciais, aliado à poliquimioterapia, pode contribuir para o controle da disseminação da infecção. Os atuais métodos de diagnóstico apresentam problemas, como: baixa sensibilidade da baciloscopia; longo tempo de realização das culturas microbiológicas; e baixa especificidade do teste cutâneo com o derivado protéico purificado do M. tuberculosis. Novos métodos de diagnóstico que utilizam antígenos específicos (por exemplo, os conhecidos em inglês como o early secreted antigenic target 6-kDa e o culture filtrate protein 10-kDa), estão sendo testados. Os genes que codificam esses antígenos estão localizados na região de diferença 1 do M. tuberculosis, M. africanum e M. bovis, mas estão ausentes no M. bovis (BCG) e na maioria das micobactérias do meio ambiente. Métodos de diagnóstico baseados na produção de interferon-gama por linfócitos T, em resposta a esses antígenos, como o QuantiFERON-TB® e o T SPOT.TB®, estão sendo testados, e superam o teste cutâneo com o derivado protéico purificado nas seguintes características: maior sensibilidade; menor reatividade cruzada devido à vacinação com o BCG ou infecção por micobactérias do meio ambiente; e tempo de execução. A introdução de métodos de diagnóstico mais específicos e sensíveis, assim como um maior entendimento dos mecanismos moleculares e celulares que regulam a interação parasito-hospedeiro, pode contribuir para um eficiente combate à tuberculose.

Tuberculosis remains a serious social and public health problem, affecting millions of people annually. The bacille Calmette-Guerin (BCG) vaccine, used prophylactically, does not impede the progression of the disease, which usually manifests as decreased cellular immunity. Early diagnosis, together with polychemotherapy, can control the dissemination of the tuberculosis infection. The current diagnostic methods present certain problems. Such problems include the low sensitivity of sputum smear microscopy, the fact that performing microbiological cultures is quite time-consuming, and the low specificity of the skin test with the purified protein derivative of M. tuberculosis. New diagnostic methods, which use specific antigens such as the early secreted antigenic target 6-kDa and culture filtrate protein 10kDa, are being evaluated. The genes that encode these antigens are located in the DNA region of difference 1 of M. tuberculosis, M. africanum and M. bovis. However, they are absent from the M. bovis (BCG) and from most environmental mycobacteria. Diagnostic methods such as QuantiFERON-TB® and T SPOT.TB®, which are based on the production of interferon-gamma by T lymphocytes, in response to those antigens, are being tested and have been found to outstrip the purified protein derivative skin test in the following characteristics: greater sensitivity; lower cross-reactivity due to BCG vaccination or infection with environmental mycobacteria; and execution time. The introduction of diagnostic methods that are more specific and sensitive, together with gaining a better understanding of the molecular and cellular mechanisms that regulate the parasite-host interaction, can increase the efficiency of strategies devised to combat tuberculosis.