Compliance with and response to hepatitis B vaccination in remaining quilombo communities in Central Brazil.

Compliance with and responses to the hepatitis B vaccine were evaluated in remaining quilombo communities in Central Brazil. A total of 708 individuals who were susceptible to hepatitis B virus infection were invited to participate in the hepatitis B vaccination program in eight communities. Although 567 (80%) individuals received the first dose, only 198 (28%) complied with the full vaccination scheme. Of 148 subjects who agreed to be tested for anti-HBs, 123 (83.1%; 95%CI: 75.9-88.6) responded to the vaccine. A geometric mean titer of 512mIU/mL (95%CI: 342.5-765.3) was found. Male sex and older age were independently associated with non-response. Additional health education programs and alternative hepatitis B vaccine schedules are needed to improve the vaccination coverage in these communities in Central Brazil.

Compliance with and response to hepatitis B vaccination in remaining quilombo communities in Central Brazil / Adesão e resposta à vacinação contra hepatite B em comunidades remanescentes de quilombos no Brasil Central

Compliance with and responses to the hepatitis B vaccine were evaluated in remaining quilombo communities in Central Brazil. A total of 708 individuals who were susceptible to hepatitis B virus infection were invited to participate in the hepatitis B vaccination program in eight communities. Although 567 (80 percent) individuals received the first dose, only 198 (28 percent) complied with the full vaccination scheme. Of 148 subjects who agreed to be tested for anti-HBs, 123 (83.1 percent; 95 percentCI: 75.9-88.6) responded to the vaccine. A geometric mean titer of 512mIU/mL (95 percentCI: 342.5-765.3) was found. Male sex and older age were independently associated with non-response. Additional health education programs and alternative hepatitis B vaccine schedules are needed to improve the vaccination coverage in these communities in Central Brazil.

A adesão e resposta à vacina contra hepatite B foram avaliadas em comunidades remanescentes de quilombos no Brasil Central. Um total de 708 indivíduos suscetíveis à infecção pelo vírus da hepatite B foi convidado para participar do programa de vacinação contra hepatite B em oito comunidades. Apesar de 567 (80 por cento) indivíduos terem recebido a primeira dose, somente 198 (28 por cento) aderiram ao esquema completo de vacinação. De 148 sujeitos que concordaram em dosar o anti-HBs, 123 (83,1 por cento; IC95 por cento: 75,9-88,6) responderam à vacina. Um título geométrico médio de 512mUI/mL (IC95 por cento: 342,5-765,3) foi encontrado. Sexo masculino e idade foram independentemente associados com ausência de resposta. Programas adicionais de educação em saúde e esquemas alternativos de vacinação contra hepatite B são necessários para melhorar a cobertura vacinal nessas comunidades no Brasil Central.

Prevalence of hepatitis C virus infection in quilombo remnant communities in Central Brazil.

In order to determine the prevalence of hepatitis C virus (HCV) infection in quilombo remnant communities in Central Brazil, 1,007 subjects were interviewed in all 12 communities existing in Mato Grosso do Sul State, Central Brazil. Blood samples were collected and sera were tested for anti-HCV by enzyme-linked immunosorbent assay. Positive samples were retested for confirmation using a line immunoassay and were also subjected to HCV RNA detection. The prevalence of HCV infection was 0.2%. This finding shows a low prevalence of HCV infection in quilombo remnant communities in Central Brazil.

Prevalence of hepatitis C virus infection in quilombo remnant communities in Central Brazil / Prevalência da infecção pelo vírus da hepatite C em comunidades remanescentes de quilombos no Brasil Central

In order to determine the prevalence of hepatitis C virus (HCV) infection in quilombo remnant communities in Central Brazil, 1,007 subjects were interviewed in all 12 communities existing in Mato Grosso do Sul State, Central Brazil. Blood samples were collected and sera were tested for anti-HCV by enzyme-linked immunosorbent assay. Positive samples were retested for confirmation using a line immunoassay and were also subjected to HCV RNA detection. The prevalence of HCV infection was 0.2 percent. This finding shows a low prevalence of HCV infection in quilombo remnant communities in Central Brazil.

Com objetivo de estimar a prevalência da infecção pelo vírus da hepatite C (HCV) em comunidades remanescentes de quilombos no Brasil Central, 1.007 indivíduos foram entrevistados nas 12 comunidades quilombolas existentes no Estado de Mato Grosso do Sul, Brasil Central. Amostras sanguíneas foram coletadas e os soros testados para anti-HCV pelo ensaio imunoenzimático. As amostras positivas foram testadas pelo ensaio confirmatório "line immunoassay" e também submetidas à detecção do RNA-HCV. A prevalência da infecção pelo HCV foi de 0,2 por cento. Este achado mostra uma baixa prevalência da infecção pelo HCV em comunidades remanescentes de quilombos no Brasil Central.

Epidemiological aspects of hepatitis C virus infection among renal transplant recipients in Central Brazil.

An investigation was conducted involving 255 renal transplant recipients in the state of Goiás, Central Brazil, to determine the prevalence of hepatitis C virus (HCV), its risk factors, the genotypes involved, and the level of alanine aminotransferase (ALT) present in the patients. All serum samples were tested for anti-HCV antibodies and HCV RNA. Forty-one patients were anti-HCV and/or HCV RNA positive, resulting in an overall HCV infection prevalence of 16.1% (95% CI: 11.9-21.3). A multivariate analysis of risk factors showed that a history of blood transfusions without anti-HCV screening, the length of time spent on hemodialysis, and renal transplantation before 1994 are all associated with HCV positivity. In HCV-positive patients, only 12.2% had ALT levels above normal. Twenty-eight samples were genotyped as genotype 1, subtypes 1a (62.5%) and 1b (31.3%), and two samples (6.2%) were genotype 3, subtype 3a. These data show a high prevalence of HCV infection and low ALT levels in the studied population. The risk factor analysis findings emphasize the importance of public health strategies such as anti-HCV screening of candidate blood and organ donors, in addition to the stricter adoption of hemodialysis-specific infection control measures. The present study also demonstrates that HCV genotype 1 (subtype 1a) is predominant in this population.

Molecular and epidemiological study on nosocomial transmission of HCV in hemodialysis patients in Brazil.

An epidemiological and molecular study of hepatitis C virus (HCV) infection was carried out in Brazilian hemodialysis centers. A total of 1,095 patients in all 15 hemodialysis centers in the State of Goiás, Brazil, were studied. All patients were interviewed for possible risk factors to HCV infection and serum samples tested for anti-HCV by ELISA and for HCV RNA by nested RT-PCR of the 5' NC region. For sequence analysis, HCV RNA amplification for the NS5B region (nt 8,279-8,619) was performed. The phylogenetic tree was generated with MrBayes, and clusters with support values above 0.85 were considered epidemiologically related. Of the 1,095 patients, 180 were anti-HCV and/or HCV RNA positive, resulting in an overall prevalence of 16.4% (95% CI: 14.3-18.7). The prevalence of HCV infection in the dialysis centers ranged from 0% to 47.7%. Multivariate analysis of risk factors revealed that history of blood transfusion not screened for anti-HCV and length of time on hemodialysis were independently associated with HCV infection in this population. One hundred six samples could be amplified and sequenced in the NS5B region. Among them, plylogenetic tree analysis revealed that 69 sequences form 13 separated clusters, which were supported by credibility intervals ranging from 85% to 100%, indicating a very close relationship among the HCV isolates and therefore a likely transmission of the virus between patients. By combining phylogenetic analysis with epidemiological data, routes of transmission between the clustered-related-patients could be suggested. These findings provide evidence for nosocomial transmission of HCV in Brazilian hemodialysis centers.

Genetic variability of hepatitis A virus strain HAF-203 isolated in Brazil and expression of the VP1 gene in Escherichia coli

The hepatitis A virus (HAV) HAF-203 strain was isolated from an acute case of HAV infection. The primary isolation of HAF-203 in Brazil and its adaptation to the FRhK-4 cell lineage allowed the production of large amounts of viral particles enabling molecular characterization of the first HAV isolate in Brazil. The aim of our study was to determine the nucleotide sequence of the HAF-203 strain genome, compare it to other HAV genomes and highlight its genetic variability. The complete nucleotide sequence of the HAF-203 strain (7472 nucleotides) was compared to those obtained earlier by others for other HAV isolates. These analyses revealed 19 HAF-specific nucleotide sequence differences with 10 amino acid substitutions. Most of the non-conservative changes were located at VP1, 2C, and 3D genes, but the 3B region was the most variable. The availability of HAF-203 complementary DNA was useful for the production of the recombinant VP1 protein, which is a major determinant of viral infectivity. This recombinant protein was shown by enzyme-linked immunoassay and blotting, to be immunogenic and resemble the native protein, therefore suggesting its value as a reagent for incorporation into diagnostic tests.

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.

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 percent (95 percent 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 percent (17/26) of the HBsAg-positive samples. Thirteen of 17 HBV DNA positive samples were genotyped. Genotype D (61.5 percent) was predominant, followed by A (30.8 percent), while genotype F was detected in only one (7.7 percent) sample.

A window of opportunity: declining rates of hepatitis B virus infection among injection drug users in Rio de Janeiro, and prospects for targeted hepatitis B vaccination.

OBJECTIVES: To measure hepatitis B virus (HBV) infection rates among injection drug users in Rio de Janeiro, Brazil, and to report their knowledge of and attitudes toward hepatitis and HBV vaccination. METHODS: 609 injection drug users recruited in Rio de Janeiro between 1999 and 2001 answered a questionnaire and were tested for hepatitis B and other blood-borne infections. Questions covered sociodemographic information, alcohol and illicit drug consumption, drug injection and sexual practices, medical history, and knowledge about HIV, AIDS and viral hepatitis. RESULTS: The prevalence of HBV infection was 27.1%, with 3.4% of the sample positive for HbsAg (active infection) and 0.8% positive for anti-HBs (indicating previous HBV vaccination). Most interviewees (81.3%) were aware of at least one form of viral hepatitis and received information from many different sources. In agreement with laboratory findings, 96.7% of the interviewees stated they had never been vaccinated against hepatitis B, but almost all unvaccinated interviewees (97.8%) said they would volunteer to be vaccinated if HBV vaccination were available. CONCLUSIONS: Few of the injection drug users surveyed had ever been vaccinated against HBV. Although most were aware of the risks posed by viral hepatitis, this awareness seldom translated into consistent behavioral change. The participants' willingness to be vaccinated against HBV suggests that the implementation of vaccination for this population may help decrease rates of hepatitis B infection.

A window of opportunity: declining rates of hepatitis B virus infection among injection drug users in Rio de Janeiro, and prospects for targeted hepatitis B vaccination

OBJETIVOS: Calcular las tasas de infección por el virus de la hepatitis B (VHB) en usuarios de drogas inyectadas en Río de Janeiro, Brasil, y dar a conocer sus conocimientos y actitudes en torno a la hepatitis y a la vacunación contra el VHB. MÉTODOS: Seiscientos nueve usuarios de drogas que se reclutaron en Río de Janeiro entre 1999 y 2001 respondieron a un cuestionario y fueron sometidos a pruebas para detectar la presencia de hepatitis B y de otras infecciones transmitidas por la sangre. Las preguntas versaban sobre aspectos sociodemográficos, el consumo de alcohol y de drogas ilícitas, el modo de inyección de las drogas y las prácticas sexuales, los antecedentes médicos y los conocimientos sobre el VIH, el sida y la hepatitis viral.RESULTADOS: La prevalencia de infección por el VHB fue de 27,1%; 3,4% de la muestra tuvo resultados positivos al HB Ag (infección activa) y 0,8% a anticuerpos anti-HBs (indicadores de que ya se ha recibido la vacuna contra el VHB). La mayor parte de las personas entrevistadas afirmaron no haber sido vacunadas contra la hepatitis B, pero casi todos las que no habían recibido la vacuna (97,8%) manifestaron estar dispuestas a vacunarse si se elaborase una vacuna. CONCLUSIONES: Pocos de los usuarios de drogas inyectadas habían sido vacunados contra el VHB. Aunque la mayor parte eran conscientes de los peligros que acarrea la hepatitis viral, ello raras veces se traducía en un cambio conductual invariable. La disposición de los participantes a vacunarse contra el VHB indica que si se implementase la vacunación en esta población se lograría reducir las tasas de hepatitis B.

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.

Hepatitis B virus infection in isolated Afro-Brazilian communities.

The prevalence and genotypes of hepatitis B virus (HBV) have distinct geographical distribution. In Brazil, some African-descendants have been maintained as small isolated communities since the slavery period. In this study, HBV infection among these communities of African origin was examined. Individuals (1,058) living in 12 communities were interviewed and serum samples screened for the presence of HBV markers. HBsAg-positive sera were tested for HBV DNA by PCR and positive samples were genotyped by restriction fragment length polymorphism (RFLP). The overall prevalence of HBV infection was 19.8% (95% CI: 17.5-22.3), ranging from 5.5% to 42.4%, depending on the communities studied. Multivariate analysis of risk factors showed that increasing age, family history of hepatitis, and sexual activity were associated significantly with this infection. HBsAg was detected in 23/1,058 (2.2%) individuals. HBV DNA was present in 2/2 of HBeAg-positive serum samples and in 18/21 (85.7%) anti-HBe-positive samples. All HBV isolates belonged to genotype A, subtype Aa. Three RFLP patterns were identified: AI (17 isolates), AIV (1 isolate), and AVI (2 isolates). These findings suggest a common introduction of HBV during the slave trade from Africa to Brazil.

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 percent, however a b decrease in positivity was detected between 1999 and 2002 (37.8 vs 16.5 percent) when the measures were fully implemented. Also, a decrease of the anti-HCV accumulated incidence in cohorts of susceptible individuals during 1993-2002 (71 percent), 1996-2002 (34.2 percent), and 1999-2002 (11.7 percent) 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, ratifying the importance of public health strategies for control and prevention of hepatitis C in the hemodialysis units.

GB virus C/hepatitis G virus infection in dialysis patients and kidney transplant recipients in Central Brazil.

In order to investigate the prevalence of GB virus C (GBV-C)/hepatitis G virus (HGV) infection in dialysis patients and kidney transplant recipients in Central Brazil and also to analyze the virus genotypes distribution, a total of 123 patients including 98 on hemodialysis, 13 on continuous ambulatory peritoneal dialysis treatment, and 12 who received kidney transplantation were interviewed in one unit of dialysis treatment in Goiania city. Blood samples were collected and serum samples tested for GBV-C/HGV RNA by polymerase chain reaction. Genotypes were determined by restriction fragment length polymorphism (RFLP) analysis. Eighteen samples were GBV-C/HGV RNA-positive, resulting in an overall prevalence of 14.6% (95% CI: 9.2-21.7). A high positivity for GBV-C/HGV RNA was observed in patients who had received kidney transplant (16.7%), followed by those on hemodialysis (15.3%), and peritoneal dialysis (7.7%). RFLP analysis revealed the presence of genotypes 1, 2, and 3 of GBV-C/HGV; more precisely, 9 (50%) samples were found belonging to the 2b subtype, 4 (22%) to the 2a subtype, 3 (17%) to genotype 1, and 2 (11%) to genotype 3. The present data indicate an intermediate prevalence of GBV-C/HGV infection among dialysis patients and kidney transplant recipients in Central Brazil. Genotype 2 (subtype 2b) seems to be the most prevalent GBV-C/HGV genotype in our region.

GB virus C/hepatitis G virus infection in dialysis patients and kidney transplant recipients in central Brazil

In order to investigate the prevalence of GB virus C (GBV-C)/hepatitis G virus (HGV) infection in dialysis patients and kidney transplant recipients in Central Brazil and also to analyze the virus genotypes distribution, a total of 123 patients including 98 on hemodialysis, 13 on continuous ambulatory peritoneal dialysis treatment, and 12 who received kidney transplantation were interviewed in one unit of dialysis treatment in Goiânia city. Blood samples were collected and serum samples tested for GBV-C/HGV RNA by polymerase chain reaction. Genotypes were determined by restriction fragment length polymorphism (RFLP) analysis. Eighteen samples were GBV-C/HGV RNA-positive, resulting in an overall prevalence of 14.6 percent (95 percent CI: 9.2-21.7). A high positivity for GBV-C/HGV RNA was observed in patients who had received kidney transplant (16.7 percent), followed by those on hemodialysis (15.3 percent), and peritoneal dialysis (7.7 percent). RFLP analysis revealed the presence of genotypes 1, 2, and 3 of GBV-C/HGV; more precisely, 9 (50 percent) samples were found belonging to the 2b subtype, 4 (22 percent) to the 2a subtype, 3 (17 percent) to genotype 1, and 2 (11 percent) to genotype 3. The present data indicate an intermediate prevalence of GBV-C/HGV infection among dialysis patients and kidney transplant recipients in Central Brazil. Genotype 2 (subtype 2b) seems to be the most prevalent GBV-C/HGV genotype in our region.

Infecção pelo vírus da hepatite B em hemofílicos em Goiás: soroprevalência, fatores de risco associados e resposta vacinal / Seroprevalence, vaccination response and risk factors for hepatitis B virus infection in hemophiliacs in Goiás

Objetivando determinar a prevalência da infecção pelo vírus da hepatite B (HBV) em hemofílicos em Goiás, analisar os fatores de risco associados e avaliar a resposta vacinal contra hepatite B, 102 pacientes foram entrevistados e amostras sangüíneas coletadas para detecção dos seguintes marcadores sorológicos: HBsAg, anti-HBs e anti-HBc. Uma prevalência global de 43,7 por cento (IC 95 por cento: 33,5-54,2) para infecção pelo HBV foi encontrada. A análise multivariada dos fatores de risco mostrou que o número de episódios transfusionais e sorologia positiva para o vírus da hepatite C estiveram significantemente associados à positividade ao HBV. Foram identificados 49 (48,1 por cento) hemofílicos susceptíveis a esta infecção, sendo imunizados 30 pacientes com a vacina recombinante Euvax-B. Destes, 28 (93,3 por cento) indivíduos apresentaram títulos de anti-HBs maiores que 10 UI/L, o que mostra uma boa resposta à vacina. Os achados deste estudo ressaltam a importância das medidas de controle e prevenção da hepatite B nesta população.

In order to study the prevalence and risk factors for hepatitis Bin hemophiliacs in Goiás, 102 patients were interviewed andblood samples collected and screened for the following serologicalmarkers: HBsAg, anti-HBs and anti-HBc. An overall prevalenceof 43.7% (95% IC: 33.5-54.2) was found to hepatitis B virus(HBV) infection. Multivariate analysis of risk factors showedthat the number of transfusions and positive serology for hepatitisC virus were significantly associated with HBV positivity. Therewere 48 (48.1%) susceptible patients for this infection, of whom30 were immunized with the Euvax-B vaccine. Among them, 28(93.3%) individuals developed anti-HBs titers higher than 10IU/L. Thus, a good response was observed in the studiedpopulation. The findings of this study emphasize the importanceof strategies of control and prevention of hepatitis B in thispopulation.

Hepatitis B and C in the hemodialysis unit of Tocantins, Brazil: serological and molecular profiles.

A survey was conducted in the hemodialysis population of the state of Tocantins, Brazil, aiming to assess the prevalence of hepatitis B virus (HBV) and hepatitis C virus (HCV) infections, to analyze associated risk factors, and also to investigate these viruses genotypes distribution. During January and March 2001, all patients (n = 100) were interviewed at the unique dialysis unit in Tocantins. Blood samples were collected and serum samples were screened for HBV serological markers. Hepatitis B surface antigen positive samples were tested for HBV DNA. All samples were also tested for anti-HCV antibodies and HCV RNA. An overall prevalence of 45% was found for HBV infection (4% were HBsAg/anti-HBc positive, 2% were anti-HBc only and 39% had anti-HBc/anti-HBs markers). Concerning HCV infection, anti-HCV and HCV RNA were detected in 13% and 14% of the subjects, respectively. Three patients were HCV RNA positive and anti-HCV negative, resulting in an overall HCV prevalence of 16%. Univariate analysis of risk factors showed that only shift and length of tile on hemodialysis were associated with HBV and HCV positivity respectively. Among the four HBsAg-positive samples, HBV DNA was detected in three of them, which were identified as genotype A by restriction fragment length polymorphism (RFLP) analysis. All 14HCV RNA-positive samples were genotyped by INNO-LiPA. Genotypes la and 3a were found in 85% and 15%, respectively. The present data show low HBsAg and HCV prevalence rates. The risk factors associated with HBV and HCV positivity suggest that nosocomial transmission may influence in spreading these viruses in the dialysis unit studied.