Simonne Almeida e Silva

Hepatitis C prevalence and risk factors in hemodialysis patients in Central Brazil: a survey by polymerase chain reaction and serological methods.

An hemodialysis population in Central Brazil was screened by polymerase chain reaction (PCR) and serological methods to assess the prevalence of hepatitis C virus (HCV) infection and to investigate associated risk factors. All hemodialysis patients (n=428) were interviewed in eight dialysis units in Goiânia city. Blood samples were collected and serum samples screened for anti-HCV antibodies by an enzyme-linked immunosorbent assay (ELISA). Positive samples were retested for confirmation with a line immunoassay (LIA). All samples were also tested for HCV RNA by the PCR. An overall prevalence of 46.7% (CI 95%: 42-51.5) was found, ranging from 20.7% (CI 95%: 8.8-38.1) to 90.4% (CI 95%: 79.9-96.4) depending on the dialysis unit. Of the 428 patients, 185 were found to be seropositive by ELISA, and 167 were confirmed positive by LIA, resulting in an anti-HCV prevalence of 39%. A total of 131 patients were HCV RNA-positive. HCV viremia was present in 63.5% of the anti-HCV-positive patients and in 10.3% of the anti-HCV-negative patients. Univariate analysis of risk factors showed that the number of previous blood transfusions, transfusion of blood before mandatory screening for anti-HCV, length of time on hemodialysis, and treatment in multiple units were associated with HCV positivity. However, multivariate analysis revealed that blood transfusion before screening for anti-HCV and length of time on hemodialysis were significantly associated with HCV infection in this population. These data suggest that nosocomial transmission may play a role in the spread of HCV in the dialysis units studied. In addition to anti-HCV screening, HCV RNA detection is necessary for the diagnosis of HCV infection in hemodialysis patients.

Hepatitis B virus infection profile in hemodialysis patients in Central Brazil: prevalence, risk factors, and genotypes

Hemodialysis patients are at high risk for hepatitis B virus (HBV) infection. A survey was conducted in the hemodialysis population of the state of Goiás, Central Brazil, aiming to assess the prevalence of HBV infection, to analyse associated risk factors, and also to investigate HBV genotypes distribution. A total of 1095 patients were interviewed in 15 dialysis units. Serum samples were screened for HBV serological markers by enzyme-linked immunosorbent assay. Hepatitis B surface antigen (HBsAg) positive samples were tested for HBV DNA by polymerase chain reaction and genotyped by restriction fragment length polymorphism. Global HBV infection prevalence was 29.8% (95% CI: 27.1-32.5). Multivariate analysis of risk factors showed that male gender, length of time on hemodialysis, and blood transfusion before 1993 were associated with HBV positivity. HBV DNA was detected in 65.4% (17/26) of the HBsAg-positive samples. Thirteen of 17 HBV DNA positive samples were genotyped. Genotype D (61.5%) was predominant, followed by A (30.8%), while genotype F was detected in only one (7.7%) sample.

PCR Assay for Monitoring Trypanosoma cruzi Parasitemia in Childhood after Specific Chemotherapy

ABSTRACT Assessment of cure of Trypanosoma cruzi infection by antibody seroconversion usually involves several years of follow-up. Parasitological negativity is useless for cure assessment, since even untreated patients mostly show negative results; conversely, positive tests are of great value because they indicate treatment failure. Here, PCR was used to assess the rate of specific chemotherapy failure in a well-characterized Brazilian cohort of T. cruzi-seropositive children, who were enrolled in a field trial of benznidazole (Bz) efficacy. Paired blood samples from 111 children were taken at baseline and 36 months after treatment with either Bz (n = 58) or a placebo (n = 53). DNA extraction and PCR amplification were carried out as previously described, and hybridization was performed with all PCR products. At the end of follow-up, PCR was positive for 39.6% of the patients in the Bz group versus 64.2% in the placebo group (P = 0.01). Untreated patients had a 1.6-fold-higher chance of remaining positive by PCR than those in the Bz group (P < 0.05). We conclude that PCR is a useful tool for revealing therapeutic failure of T. cruzi infection on a short-term basis.

Decline of hepatitis C infection in hemodialysis patients in Central Brazil: a ten years of surveillance

Hepatitis C virus (HCV) has been a significant problem for hemodialysis patients. However this infection has declined in regions where the screening for anti-HCV in blood banks and hemodialysis-specific infection control measures were adopted. In Brazil, these measures were implemented in 1993 and 1996, respectively. In addition, all studied units have implemented isolation of anti-HCV positive patients since 2000. In order to evaluate the impact of these policies in the HCV infection prevalence, accumulated incidence, and risk factors in hemodialysis population of Goiânia City, Central Brazil, all patients were interviewed and serum samples tested for HCV antibodies in 1993, 1996, 1999, and 2002. In the first six years (1993-1999), anti-HCV prevalence increased from 28.2 to 37.2%, however a b decrease in positivity was detected between 1999 and 2002 (37.8 vs 16.5%) when the measures were fully implemented. Also, a decrease of the anti-HCV accumulated incidence in cohorts of susceptible individuals during 1993-2002 (71%), 1996-2002 (34.2%), and 1999-2002 (11.7%) was found. Analysis of risk factors showed that length of time on hemodialysis, blood transfusion before screening for anti-HCV and treatment in multiple units were statistically associated with anti-HCV (p < 0.05). Our study showed a significant decline of hepatitis C infection in hemodialysis patients of Central Brazil, gratifying the importance of public health strategies for control and prevention of hepatitis C in the hemodialysis units.

Population-based surveillance of pediatric pneumonia: use of spatial analysis in an urban area of Central Brazil

This study examined the spatial distribution of childhood community-acquired pneumonia detected through prospective surveillance in Goiânia, Brazil. Three spatial analysis techniques were applied to detect intra-urban geographic aggregation of pneumonia cases: Kernel method, nearest neighbor hierarchical technique, and spatial scan statistic. A total of 724 pneumonia cases confirmed by chest radiography were identified from May 2000 to August 2001. All cases were geocoded on a digital map. The annual pneumonia risk rate was estimated at 566 cases/100,000 children. Analysis using traditional descriptive epidemiology showed a mosaic distribution of pneumonia rates, while GIS methodologies showed a non-random pattern with hot spots of pneumonia. Cluster analysis by spatial scan statistic identified two high-risk areas for pneumonia occurrence, including one most likely cluster (RR = 2.1; p < 0.01) and one secondary cluster (RR = 1.3; p = 0.01). The data used for the study are in line with recent WHO-led efforts to improve and standardize pediatric pneumonia surveillance in developing countries and show how GIS and spatial analysis can be applied to discriminate target areas of pneumonia for public heath intervention.

Vigilância de doenças endêmicas em áreas urbanas: a interface entre mapas de setores censitários e indicadores de morbidade

In this article we discuss the methodological issues associated with the creation of a surveillance system for endemic diseases in urban areas based on analysis of populations at risk and on spatially referenced epidemiological indicators. We comment on the systems basic requirements, selection criteria for socioeconomic variables, and methodological steps to combine these variables so as to construct a census-based deprivation index. We also present the ways we solved some operational problems related to generation of digitized census tracts maps and linkage of morbidity data from different sources. This approach, spatial organization into account in surveillance of endemic diseases, exemplified here by tuberculosis and leprosy, allows for the interaction of several official data sets from census and health services in order to geographically discriminate inner-city risk strata. Criteria for constructing these risk strata were considered a useful tool for health planning and management activities for the control of endemic diseases in cities.

Soroprevalência e fatores de risco para a infecção pelo vírus da hepatite B pelos marcadores AgHBs e anti-HBs em prisioneiros e primodoadores de sangue

Two cross-sectional surveys on hepatitis B virus (HBV) infection were carried out among 1,033 volunteer first-time blood donors in five blood banks (3 private, 2 public) and among 201 prisoners in the Penitentiary Center of Industrial Activity, in Goiania, Central Brazil, between June 1988 and February 1989. Those surveys were part of a major study designed to estimate seroprevalence of HBsAg and anti-HBsAg markers by ELISA test, and to study risk factors associated with seropositivity. The presence of any serum marker was considered as previous exposure to HBV. A standard questionnaire was applied to both populations to evaluate previous blood transfusion, number of sexual partners, homo/bisexual activity, history of sexually transmitted diseases, drug abusers, use of parenteral medicine, acupuncture, tattooing and VDRL seropositivity. Seroprevalence varied from 12.8% to 26.4% in blood donors and prisoners, respectively, (p less than 0.05) and increased with age (X2 trend=14.0 p less than 0.05%). Prisoners had higher percentages of all risk factors investigated than blood donors, with the exception of number of sexual partners. Among all risk factors studied, age, imprisonment and tattooing were statistically associated with seropositivity, even after multivariate analysis controlling for age and reclusion. The paper discusses the methodologic issues related to this epidemiologic investigation.Foram rastreados 1.033 primodoadores de sangue e 201 prisioneiros, para a infeccao pelo virus da hepatite B (VHB), durante o periodo de junho de 1988 a fevereiro de 1989, em Goiânia, GO (Brasil). Foi estimada a soroprevalencia dos marcadores AgHBs e anti-HBs, e estudados os fatores de risco associados a soropositividade. Os testes sorologicos foram realizados pela tecnica de ELISA e a presenca de qualquer dos marcadores estudados foi interpretada como exposicao ao virus da hepatite B. Um questionario padronizado foi aplicado em ambos os grupos populacionais para avaliar: transfusao sanguinea previa, numero de parceiros sexuais, atividade homo/bissexual, historia de outras doencas sexualmente transmissiveis, uso de droga injetavel, uso de medicacao injetavel, acupuntura, tatuagem e soropositividade ao VDRL. Foram obtidas soroprevalencias globais para a infeccao pelo VHB de 26,4% e 12,8% para a populacao carceraria e de primodoadores respectivamente, diferenca estatisticamente significante (p<0,05), observando-se tendencia crescente da soropositividade com a idade (X² para tendencia = 14,0, p<0,05). A populacao carceraria apresentou maiores percentuais de exposicao a todos os fatores de risco quando comparada aos primodoadores, a excecao do numero de parceiros sexuais. Grupo etario, encarcera-mento e presenca de tatuagem foram os fatores de risco estatisticamente significantes associados a soropositividade, mesmo apos analise multivariada controlada por idade e encarceramento. Foram discutidas as dificuldades metodologicas que poderiam ter influenciado nos resultados.Foram rastreados 1.033 primodoadores de sangue e 201 prisioneiros, para a infeccao pelo virus da hepatite B (VHB), durante o periodo de junho de 1988 a fevereiro de 1989, em Goiânia, GO (Brasil). Foi estimada a soroprevalencia dos marcadores AgHBs e anti-HBs, e estudados os fatores de risco associados a soropositividade. Os testes sorologicos foram realizados pela tecnica de ELISA e a presenca de qualquer dos marcadores estudados foi interpretada como exposicao ao virus da hepatite B. Um questionario padronizado foi aplicado em ambos os grupos populacionais para avaliar: transfusao sanguinea previa, numero de parceiros sexuais, atividade homo/bissexual, historia de outras doencas sexualmente transmissiveis, uso de droga injetavel, uso de medicacao injetavel, acupuntura, tatuagem e soropositividade ao VDRL. Foram obtidas soroprevalencias globais para a infeccao pelo VHB de 26,4% e 12,8% para a populacao carceraria e de primodoadores respectivamente, diferenca estatisticamente significante (p<0,05), observando-se tendencia crescente da soropositividade com a idade (X² para tendencia = 14,0, p<0,05). A populacao carceraria apresentou maiores percentuais de exposicao a todos os fatores de risco quando comparada aos primodoadores, a excecao do numero de parceiros sexuais. Grupo etario, encarcera-mento e presenca de tatuagem foram os fatores de risco estatisticamente significantes associados a soropositividade, mesmo apos analise multivariada controlada por idade e encarceramento. Foram discutidas as dificuldades metodologicas que poderiam ter influenciado nos resultados.

Computer-aided diagnosis in chest radiography for detection of childhood pneumonia.

OBJECTIVES This article presents a novel approach based on computer-aided diagnostic (CAD) scheme and wavelet transforms to aid pneumonia diagnosis in children, using chest radiograph images. The prototype system, named Pneumo-CAD, was designed to classify images into presence (PP) or absence of pneumonia (PA). MATERIALS AND METHODS The knowledge database for the Pneumo-CAD comprised chest images confirmed as PP or PA by two radiologists trained to interpret chest radiographs according to the WHO guidelines for the diagnosis of pneumonia in children. The performance of the Pneumo-CAD was evaluated by a subset of images randomly selected from the knowledge database. The retrieval of similar images was made by feature extraction using wavelets transform coefficients of the image. The energy of the wavelet coefficients was used to compose the feature vector in order to support the computational classification of images as PP or PA. Methodology I worked with a rank-weighted 15-nearest-neighbour scheme, while methodology II employed a distance-dependent weighting for image classification. The performance of the prototype system was assessed by the ROC curve. RESULTS Overall, the Pneumo-CAD using the Haar wavelet presented the best accuracy in discriminating PP from PA for both, methodology I (AUC=0.97) and methodology II (AUC=0.94), reaching sensitivity of 100% and specificity of 80% and 90%, respectively. CONCLUSION Pneumo-CAD could represent a complementary tool to screen children with clinical suspicion of pneumonia, and so to contribute to gather information on the burden of-pneumonia estimates in order to help guide health policies toward preventive interventions.

Survey of nonsusceptible nasopharyngeal Streptococcus pneumoniae isolates in children attending day-care centers in Brazil.

A survey of nasopharyngeal carriage of penicillin nonsusceptible pneumococcal (PNSp) isolates was conducted among 1192 children attending 62 day care centers in Brazil, where pneumococcal vaccination has not been routinely introduced. Nasopharyngeal pneumococcal carriage was detected in 686 (57.6%) infants, and 178 (25.9%) of them carried PNSp isolates. Being less than 24 months of age, hospitalization in the previous 3 months, and recurrent acute otitis media were independently associated with PNSp. Serotypes 14, 23F, 19A, 6A, 6B and 19F were the most common serotype isolated accounting for 80% of the PNSp. A high proportion (35/332) of non-(sero)typeable isolates was detected, 62.9% of them PNSp. Serotypes coverage projected for the pneumococcal conjugate vaccine (PCV) 13-valent vaccine (72%) was significantly higher compared with PCV7 (58.4%) and PCV 10-valent vaccine (59.3%).

Prevalence of hepatitis C Virus infection among hemophiliacs in Central Brazil

In order to investigate the hepatitis C virus (HCV) infection prevalence and risk factors in hemophiliacs in Central Brazil, 90 patients were interviewed and serum samples tested for HCV RNA and anti-HCV antibodies. An overall prevalence of 63.3% (CI 95%: 53.0-72.7) was found. Multivariate analysis of risk factors showed that number of blood transfusions was significantly associated with this infection. Most hemophiliacs received locally produced cryoprecipitate. All infected patients were transfused before the screening of blood units for anti-HCV. However, hemophiliacs who received exclusively screened cryoprecipitate were HCV negative. It confirms the expected decline in transfusion-acquired hepatitis C.