Hepatitis C virus infection in hemodialysis patients in Maracaibo, Venezuela / Infecção pelo vírus da Hepatite C em pacientes em hemodiálise em Maracaibo, Venezuela

Over a two year period, the incidence of hepatitis C virus (HCV) infection was evaluated in 29 hemodialysis patients, aged between 15 and 75 years (mean ± SD: 45 ± 39.5 years), from the University Hospital Hemodyalisis Unit, Maracaibo, Zulia State, Venezuela. Anti-HCV antibodies were determined using a fourth generation ELISA (Innotest HCV Ab IV) kit and positive blood samples were tested using a recombinant assay kit (Inno-LIA HCV Ab III), both kits from Innogenetics N.V., Belgium. The findings indicate a lack of HCV seroconversion in the hemodialysis patients over the study period, confirmed by the recombinant assay. Risk factors for HCV infection were 0.3270 (95 percent confidence interval: 0.01323-8.080) in patients undergoing hemodialysis. The findings suggest a lack of significant sources for HCV infection due to the preventive measures to avoid its transmission in the hemodialysis unit.

Durante período de 2 anos, estudamos a incidência da infecção pelo vírus da hepatite C (VHC) em 29 pacientes em tratamento de diálise, com idades entre 15 e 75 anos (c ± DS; 45 ± 39,5 anos), procedentes da unidade de hemodiálise do Hospital Universitário de Maracaibo, Estado Zulia, Venezuela. Para a detecção dos anticorpos contra o VHC (anti-VHC) utilizamos a técnica de imunoensaio enzimático (ELISA, Innotest HCV Ab IV) e em amostras reativas por ELISA, utilizamos o método de immunoblot recombinante de terceira geração (Inno-LIA HCV Ab III), ambos da casa comercial Innogenetics N.V., Bélgica. Os resultados demonstram ausência de soroconversão ao VHC nos pacientes hemodializados durante o período estudado, o que foi confirmado pelo método de imunoblot recombinante. Os fatores de risco ao VHC foram 0,327 (95 por cento CI: 0,01323 - 8,080) nos pacientes submetidos ao tratamento de diálise. Nossos resultados sugerem ausência de fontes de infecção neste centro de hemodiálise e que as medidas universais de controle de infecção são cumpridas.

Seroepidemiological study of human cysticercosis with blood samples collected on filter paper, in Lages, State of Santa Catarina, Brazil, 2004-2005 / Estudo soroepidemiológico da cisticercose humana com amostras de sangue total coletado em papel filtro, em Lages, Estado de Santa Catarina, 2004-2005

INTRODUCTION: Human serofrequency of antibodies against Taenia solium antigens was determined and risk factors for cysticercosis transmission were identified. METHODS: Individuals (n=878) from periurban and rural locations of Lages, SC, were interviewed to gather demographic, sanitary and health information. Interviews and blood sample collections by finger prick on Whatman filter paper were performed from August 2004 to May 2005. Observation determined that 850 samples were suitable for analysis and were tested by ELISA using vesicular fluid of Taenia crassiceps heterologous antigen. To ensure the reliability of the results, 77 samples of the dried blood were matched with sera. The reactive samples were submitted to a serum confirmatory immunoblot (IB) test using purified Taenia crassiceps glycoproteins. RESULTS: The ELISA results for the dried blood and serum samples were statistically consistent. ELISA was positive in 186 (21.9 percent) out of 850 individuals. A group of 213 individuals were asked to collect vein blood for IB (186 with positive result in ELISA and 27 with inappropriate whole blood samples) and 130 attended the request. The IB was positive in 29 (3.4 percent) out of 850 individuals. A significant correlation (p = 0.0364) was determined among individuals who tested positive in the IB assay who practiced both pig rearing and kitchen gardening. CONCLUSIONS: ELISA with dried blood eluted from filter paper was suitable for cysticercosis population surveys. In Lages, human infection was associated with pig rearing and kitchen gardening. The prevalence index was compatible with other Latin American endemic areas.

INTRODUÇÃO: O primeiro levantamento sobre cisticercose humana e identificação dos fatores de risco associados à transmissão, foram realizados em Lages, SC. MÉTODOS: Oitocentos e setenta e sete voluntários de regiões periurbana e rural foram entrevistados e forneceram informações demográficas e condições sanitárias e de saúde. Amostras de sangue foram coletadas por meio de punção digital em papel filtro entre agosto 2004 e maio 2005. Verificou-se que 850 amostras estavam adequadas para análise. No ELISA, utilizou-se o antígeno heterólogo liquido vesicular de Taenia crassiceps. Para assegurar a confiabilidade dos resultados de ELISA, foram pareadas 77 amostras de soro e sangue eluido do papel filtro. A confirmação do diagnóstico sorológico foi feita por immunoblot (IB) com glicoproteínas purificadas de Taenia crassiceps. RESULTADOS: A reatividade de IgG eluída de sangue em papel filtro mostrou-se compatível com a dos soros correspondentes. A triagem por ELISA de 850 indivíduos revelou 186 (21,9 por cento) positivos. De 213 pessoas convidadas a colher soro para IB (186 ELISA positivo e 27 com amostras de sangue total inadequadas), compareceram 130. O IB foi positivo em 29 (3,4 por cento) de 850 amostras. Houve correlação significativa entre IB positivo e a prática de criação de suínos e de horta caseira (p = 0,0364). CONCLUSÕES: ELISA com sangue total em papel filtro mostrou-se adequado para inquéritos populacionais para cisticercose. A transmissão da cisticercose humana na área estudada mostrou correlação com criação suína domestica e horta caseira. A prevalência obtida foi semelhante à relatada em áreas endêmicas da América Latina.

Diagnosis of Chagas disease: what has been achieved? What remains to be done with regard to diagnosis and follow up studies?

In the acute phase and in the chronic forms of Chagas disease, the etiological diagnosis may be performed by detection of the parasite using direct or indirect parasitological methods and by the presence of antibodies in the serum by way of serological tests. Several techniques are easily available, ranging from the simplest wet smear preparation to immuno-enzymatic assays with recombinant antigens that will meet most diagnostic needs. Other tests under evaluation include a molecular test using polymerase chain reaction, which has shown promising results and may be used as a confirmatory test both in the acute and chronic phases of the disease. Better rapid tests are needed for diagnosis, some of which are already under evaluation. Additionally, there is a need for tools that can identify patients cured shortly after specific treatment. Other needs include a marker for prognosis and early diagnosis of congenital transmission.

Hepatitis C as a risk factor for diabetes type 2: lack of evidence in a hospital in central-west Brazil

In order to assess the importance of HCV infection as a possible risk factor for type 2 diabetes mellitus, a case-control study was conducted, comparing the prevalence of HCV infection among diabetic and non-diabetic patients. Diabetic outpatients attending to a University Hospital in Central-West Brazil were evaluated between April and October 2005. A control group composed by patients from the same institution was matched by gender and age. Candidates to control group were included only if fasting glucose measures were under 100 mg/dL. Diabetics and controls had blood samples taken in order to test for antibodies against HCV (anti-HCV) by enzyme-immunoassay. Polymerase chain reaction and immunoblot were performed to confirm the anti-HCV status. Each group included 206 participants. Despite of the groups were in general comparable. The diabetics had a greater body mass average and smaller family income. The prevalence of confirmed anti-HCV in the diabetic group was of 1.4 percent, which was similar to the controls (1 percent). Finding statistical difference may have been hampered by the low frequency of HCV infection in both groups. It was not possible to demonstrate a role of HCV as an etiologic factor in type 2 diabetes, since HCV infected patients represented a small portion of the overall diabetes cases. This finding does not allow to recommend regular screening for HCV infection in type 2 diabetics in this region.

Immunoblotting analyses using two-dimensional gel electrophoresis of Trypanosoma cruzi excreted-secreted antigens

Formas tripomastigotas de Trypanosoma cruzi excretam/secretam uma complexa mistura de moléculas antigênicas. Essa mistura é chamada trypomastigote excreted-secreted antigens e contém uma banda de massa molecular em torno de 150-160kDa que possui excelente performance para diagnóstico de doença de Chagas em immunoblotting. No presente estudo foi caracterizado parcialmente, por gel bidimensional, a proteína de 150-160kDa pela análise da reatividade de anticorpos de pacientes chagásicos nas diversas fases da doença. Proteínas do trypomastigote excreted-secreted antigens foram separadas por eletroforese de alta resolução em duas dimensões (2D) e submetidas a immunoblotting com soros de pacientes chagásicos e não chagásicos. A proteína de 150-160kDa foi identificada em quatro isoformas com pontos isoelétricos variando entre 6,2 a 6,7. As quatro isoformas foram reconhecidas por anticorpos IgM na fase aguda e por anticorpos IgG na fase crônica da doença de Chagas. A isoforma de 150-160kDa, com ponto isoelétrico de aproximadamente 6,4 tornou-se imunodominante dentre as demais com a progressão da doença. Não foi detectada reatividade cruzada com os soros de pacientes não chagásicos ou pacientes infectados com Leishmania sp. Os dados obtidos nesse trabalho, reforçam a importância da utilização do trypomastigote excreted-secreted antigens para o diagnóstico sorológico da doença de Chagas.

Allergy to house dust mites and asthma

House dust mites have been shown to be important sources of indoor allergens associated with asthma and other allergic conditions. Asthma is a chronic respiratory disease that affects millions of people worldwide, and numerous scientific studies have shown that the prevalence of asthma is increasing. The most common dust mite species around the world include Dermatophagoides pteronyssinus (Dp), Dermatophagoides farinae (Df), Euroglyphus maynei (Em) and Blomia tropicalis (Bt). Over the past three decades, many important allergens from these species have been identified and characterized at the molecular level. The biological function of several house dust mite allergens has been elucidated, with many of them showing enzymatic activity. However, Bt allergens remain the least studied, even though this mite is very common in tropical and subtropical regions of the world, including Puerto Rico. Therefore, it is very important to include Bt in diagnostic and therapeutic strategies for house dust mite induced allergy and asthma, particularly in areas where Bt exposure and sensitization is high. Recombinant DNA technology, as well as other molecular biology and immunological techniques, have played a fundamental role in advances towards a better understanding of the biology of house dust mites and their role in allergic diseases. This kind of study also contributes to the understanding of the complex immunologic mechanisms involved in allergic reactions. The development of effective diagnostic and therapeutic approaches depends on the continuity of research of house dust mite allergens. The objectives of this review are to describe the most important aspects of house dust mite allergy and to acquaint the scientific community with the latest findings pertaining to house dust mite allergens, particularly those derived from Bt.

Hepatitis C virus infection in a Brazilian population with sickle-cell anemia

Patients with sickle-cell anemia submitted to frequent blood transfusions are at risk of contamination with hepatitis C virus (HCV). Determination of HCV RNA and genotype characterization are parameters that are relevant for the treatment of the viral infection. The objective of the present study was to determine the frequency of HCV infection and the positivity for HCV RNA and to identify the HCV genotype in patients with sickle-cell anemia with a history of blood transfusion who had been treated at the Hospital of the HEMOPE Foundation. Sera from 291 patients were tested for anti-HCV antibodies by ELISA 3.0 and RIBA 3.0 Chiron and for the presence of HCV RNA by RT-PCR. HCV genotyping was performed in 19 serum samples. Forty-one of 291 patients (14.1 percent) were anti-HCV positive by ELISA and RIBA. Both univariate and multivariate analysis showed a greater risk of anti-HCV positivity in those who had started a transfusion regime before 1992 and received more than 10 units of blood. Thirty-four of the anti-HCV-positive patients (34/41, 82.9 percent) were also HCV RNA positive. Univariate analysis, used to compare HCV RNA-negative and -positive patients, did not indicate a higher risk of HCV RNA positivity for any of the variables evaluated. The genotypes identified were 1b (63 percent), 1a (21 percent) and 3a (16 percent). A high prevalence of HCV infection was observed in our patients with sickle-cell anemia (14.1 percent) compared to the population in general (3 percent). In the literature, the frequency of HCV infection in sickle-cell anemia ranges from 2 to 30 percent. The serological screening for anti-HCV at blood banks after 1992 has contributed to a better control of the dissemination of HCV infection. Because of the predominance of genotype 1, these patients belong to a group requiring special treatment, with a probable indication of new therapeutic options against HCV

Isolamento de genes que codificam proteínas excretadas-secretadas pelo Trypanosoma cruzi (TESA) com potencial para imunodiagnóstico / isolation of genes that codify excreted-secreted antigens for the Trypanosoma cruzi (TESA) with potential for imunodiagnosis

O perfil de antigenicidade das proteínas excretadas-secretadas pelas formas tripomastigotas (TESA) do T. cruzi apresenta, por immunoblotting (TESA-blot), duas moléculas imunodominantes que permitem o diagnóstico diferencial da doença de Chagas. TESA-blot mostra uma banda de 150-160 kDa amplamente reconhecida por soros de pacientes de fase crônica e uma outra, denominada SAPA (shed acute phase antigen), preferencialmente reativa com soros da fase aguda da doença de Chagas (Umezawa et al., 1996b). Além disso, moléculas de 160 kDa presentes somente na infecçäo ativa, consideradas potentes candidatas como marcadores de cura da doença de Chagas, foram descritas como alvo de anticorpos líticos (Krautz et al., 2000)...

Evaluation of anti-Schistosoma mansoni igG antibodies in patients with chronic schistosomiasis mansoni before and after specific treatment

The circumoval precipitin test (COPT), enzyme-linked immunosorbent assay (ELISA) and the immunoblotting anti-adult worm antigen (AWA) and soluble egg antigen (SEA) tests were applied to 17 chronically schistosome-infected patients for the detection of anti-Schistosoma mansoni antibodies before and on four occasions after oxamniquine administration over a period of six months. Compared to a control group, schistosomiasis patients showed high levels of IgG antibodies in AWA and SEA-ELISA. A decrease in IgG levels was observed six months after treatment, although negative reactions were not obtained. Significant decreases in IgG1, IgG3 and, mainly, IgG4, but not anti-SEA IgG2 levels were observed six months after treatment, again without negativity. Analysis of anti-AWA IgG antibodies by immunoblotting before treatment showed a 31 kDa strand in 14 patients (82 percent) which disappeared in three cases up to six months after treatment; furthermore, anti-SEA IgG antibodies showed the same band in nine patients (53 percent) before treatment, which disappeared in only four cases up to six months after treatment

IgG recognizing 21-24 kDa and 30-33 kDa tachyzoite antigens show maximum avidity maturation during natural and accidental human toxoplasmosis

We describe the avidity maturation of IgGs in human toxoplasmosis using sequential serum samples from accidental and natural infections. In accidental cases, avidity increased continuously throughout infection while naturally infected patients showed a different profile. Twenty-five percent of sera from chronic patients having specific IgM positive results could be appropriately classified using exclusively the avidity test data. To take advantage of the potentiality of this technique, antigens recognized by IgG showing steeper avidity maturation were identified using immunoblot with KSCN elution. Two clusters of antigens, in the ranges of 21-24 kDa and 30-33 kDa, were identified as the ones that fulfill the aforementioned avidity characteristics