Marize Pereira Miagostovich

Molecular Detection and Characterization of Gastroenteritis Viruses Occurring Naturally in the Stream Waters of Manaus, Central Amazônia, Brazil

ABSTRACT To assess the presence of the four main viruses responsible for human acute gastroenteritis in a hydrographic network impacted by a disordered urbanization process, a 1-year study was performed involving water sample collection from streams in the hydrographic basin surrounding the city of Manaus, Amazonas, Brazil. Thirteen surface water sample collection sites, including different areas of human settlement characterized as urban, rural, and primary forest, located in the Tarumã-Açu, São Raimundo, Educandos, and Puraquequara microbasins, were defined with a global positioning system. At least one virus was detected in 59.6% (31/52) of the water samples analyzed, and rotavirus was the most frequent (44.2%), followed by human adenovirus (30.8%), human astrovirus (15.4%), and norovirus (5.8%). The viral contamination observed mainly in the urban streams reflected the presence of a local high-density population and indicated the gastroenteritis burden from pathogenic viruses in the water, principally due to recreational activities such as bathing. The presence of viral genomes in areas where fecal contamination was not demonstrated by bacterial indicators suggests prolonged virus persistence in aquatic environments and emphasizes the enteric virus group as the most reliable for environmental monitoring.

Dengue virus type 3 in Rio de Janeiro, Brazil

Dengue virus type 3 was isolated for the first time in the country as an indigenous case from a 40 year-old woman presenting signs and symptoms of a classical dengue fever in the municipality of Nova Iguaçu, State of Rio de Janeiro. This serotype has been associated with dengue haemorrhagic epidemics and the information could be used to implement appropriate prevention and control measures. Virological surveillance was essential in order to detected this new serotype.

Evaluation of an IgG enzyme-linked immunosorbent assay for dengue diagnosis

BACKGROUND The hemagglutination inhibition (HI) test has been one of the standards, with the IgM antibody capture ELISA (MAC-ELISA), for the diagnosis of dengue virus infections. The spread of dengue throughout the world and the increasing number of cases to be tested makes an ELISA-format test for IgG antibodies to replace the HI test highly desirable. OBJECTIVES Evaluate the use of the IgG-ELISA as a substitute for the HI test in dengue diagnosis. STUDY DESIGN Paired serum samples defined as being from primary or secondary dengue virus infections by HI, were tested by an ELISA that detects IgG antibodies. The correlations of titers and serologic interpretations between these two tests were examined. RESULTS The IgG-ELISA showed a low correlation with the HI in primary infections, and a higher correlation in secondary infections because of the influence of IgM antibodies in the HI test. Nevertheless, IgG ELISA titers could be reliably associated with primary or secondary infections when analyzed by days after onset of symptoms, and can be used to characterize the immune response after flavivirus infections. CONCLUSION The combination of the IgM and IgG ELISAs may be used to serologically diagnose dengue virus infections, since the IgG ELISA can substitute for the HI test in characterizing the immune response to dengue virus infections.

Analysis of adenoviruses and polyomaviruses quantified by qPCR as indicators of water quality in source and drinking-water treatment plants

Three drinking-water treatment plants were analyzed for the presence of human adenoviruses (HAdV) and JC polyomavirus (JCPyV), previously suggested as viral contamination indicators, in order to define their water quality in relation to the presence of viral pathogens and the efficiency of the treatments applied. The 90% of the river water samples had positive results of HAdV (10(1)-10(4) genome copies (GC)/L); and 48%, of JCPyV (10(0)-10(3)GC/L). Lower concentrations of HAdV and JCPyV were found in different treatment steps of the plants in absence of bacterial standards. Virus removal efficiencies were higher than 5 logs in plants 1 and 3 and could be quantified as >2 logs in plant 2. However, three post-chlorinated samples from plants 2 and 3 (11%) were found to be positive for HAdV by qPCR, but did not show infectivity in the cell cultures assayed. Simple methods based on the adsorption-elution of viruses from glass wool give low-cost and efficient virus recovery from source water and large-volume water samples. Quantification of JCPyV and HAdV using qPCR is useful for evaluating virus removal efficiency in water treatment plants, identification of Hazard Analysis and Critical Control Points (HACCP) and as a molecular index of the virological quality of water. Though infectivity is not guaranteed when using qPCR techniques in water treated with disinfection processes, the quality of source water, where viruses have proved to have infective capabilities, and the removal efficiency of viral particles may be efficiently quantified.

Dengue Virus Type 3, Brazil, 2002

An explosive epidemic of DENV-3 in 2002 was the most severe dengue epidemic reported in Brazil since dengue viruses were introduced.

Characterisation of Lymphocyte Response and Cytokine Patterns in Patients with Dengue Fever

It is believed that the pathogenesis of dengue is generated by a deregulation of the immunological response. Dengue virus-infected monocytes/macrophages are likely to secrete monokines, which play a role in clinical features observed in patients with dengue haemorrhagic fever or dengue shock syndrome. This is a report on a study on 45 individuals presenting clinical and laboratory characteristics of dengue virus infection. During the acute phase of infection, immunophenotyping of peripheral mononuclear leukocytes was carried out in 19 patients and demonstrated a reduced frequency of CD2+ lymphocytes and their CD4+ and CD8+ subsets. Normal ratios were recovered during convalescence. Also, during the acute phase, mononuclear cells proliferated poorly in response to mitogens and dengue antigens as detected by incorporation of radiolabeled thymidine. During convalescence the lymphoproliferative response was re-established. In addition, the presence of circulating cytokines was investigated in the plasma of the same 45 patients. Concentrations of tumour necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin-10 (IL-10) and soluble tumor necrosis factor receptor (sTNF-Rp75) were found to be significantly elevated in patients when compared to normal controls. The increase in TNF-alpha was correlated with haemorrhagic manifestations and the increase in IL-10 with platelet decay. The data demonstrate that during the acute phase of dengue infection subsets of T lymphocytes are depressed in terms of both rate and function and provide evidence that circulating pro-inflammatory cytokines, such as TNF-alpha, are important in the pathogenesis and severity of dengue. IL-10 may be downregulating lymphocyte and platelet function.

Dengue haemorrhagic fever in the state of Rio de Janeiro, Brazil: a study of 56 confirmed cases.

We studied 56 cases of serologically confirmed dengue haemorrhagic fever living in the metropolitan area of Niterói and surrounding cities in the state of Rio de Janeiro, Brazil. The most frequent findings were fever and myalgia. Spontaneous haemorrhagic manifestations occurred in 46 patients, and 23 of these had more than one kind of bleeding; petechiae and bleeding gums were the most frequent association. The distribution according to the World Health Organizations criteria of severity was 6 in grade I, 23 in grade II, 24 in grade III and 3 in grade IV.

Assessment of adenovirus, hepatitis A virus and rotavirus presence in environmental samples in Florianopolis, South Brazil

Aims:  To assess the presence of human adenovirus (HAdV), hepatitis A (HAV) virus and rotavirus A (RV‐A) in environmental samples from the Southern region of Brazil and to provide viral contamination data for further epidemiological studies and governmental actions.

Prevalence and Molecular Epidemiology of Noroviruses in Hospitalized Children With Acute Gastroenteritis in Rio de Janeiro, Brazil, 2004

Background: The role of noroviruses (NoV) as a cause of gastroenteritis outbreaks is well documented; however, the importance of NoV infections in hospitalized children is not well established. The aim of this study was to determine the prevalence and the genetic diversity of NoV in hospitalized children. Methods: Three-hundred eighteen fecal samples were collected from January to December 2004, from children with acute gastroenteritis in 3 public hospitals in Rio de Janeiro, Brazil. The prevalence and genetic diversity of NoV was carried out by using genome amplification and sequencing of polymerase and capsid genes. Results: NoV infections were detected in 65 (20%) of the samples, of which 11 (4%) were mixed infections with rotavirus. Infants up to 1-year-old were the most affected and a peak of virus detection was observed in autumn and spring seasons. Dehydration and diarrhea were the inclusion criterion; coughing (51%), vomiting (33%), and fever (22%) were the main clinical manifestations. Phylogenetic analysis showed that Genogroup II and GII/4 were prevalent. Two potential recombinant strains based in the different clustering pattern were observed. Conclusions: This study demonstrated the importance of NoV infections causing severe acute gastroenteritis in hospitalized children in Rio de Janeiro, Brazil. Molecular epidemiology surveillance determining the circulation pattern of different genotypes and recombinant strains is helpful for designing prevention strategies of NoV transmission in children. Studies concerning the prevalence and the molecular epidemiology of gastroenteric viruses in hospitalized children are particularly important to evaluate the impact of the rotavirus vaccine in Brazil.

Evaluation of an adsorption–elution method for detection of astrovirus and norovirus in environmental waters

Human astroviruses (HAstV) and noroviruses (NoV) are shed frequently at high concentrations and persist for long periods in the environment, raising a significant health risk of water-related gastroenteritis. The aim of this study was to evaluate an adsorption-elution method with an HA (mixed cellulose esters) negatively charged membrane to determine the best recovery of HAstV and NoV from different environmental waters. As the presence of MgCl(2) affects viral adsorption onto the membrane, three different MgCl(2) concentrations were evaluated. The best recovery of both NoV and HAstV from mineral and river water samples was between 18% and 64%, while recovery from tap water and sea water samples was between 3% and 14%. These results suggest that detection and recovery of each enteric virus with this adsorption-elution method requires a specific MgCl(2) concentration and depends on the source of environmental water tested. The combination of the HA negatively charged membrane to concentrate viruses with quantitative PCR detection allows for the identification of gastroenteritis viruses implicated in acute outbreaks of gastroenteritis.