Prevalence and clinical aspects of respiratory syncytial virus A and B groups in children seen at Hospital de Clínicas of Uberlândia, MG, Brazil.

Respiratory syncytial virus (RSV) is well recognized as the most important pathogen causing acute respiratory disease in infants and young children, mainly in the form of bronchiolitis and pneumonia. Two major antigenic groups, A and B, have been identified; however, there is disagreement about the severity of the diseases caused by these two types. This study investigated a possible association between RSV groups and severity of disease. Reverse transcription-polymerase chain reaction was used to characterize 128 RSV nasopharyngeal specimens from children less than five years old experiencing acute respiratory disease. A total of 82 of 128 samples (64.1%) could be typed, and, of these, 78% were group A, and 22% were group B. Severity was measured by clinical evaluation associated with demographic factors: for RSV A-infected patients, 53.1% were hospitalized, whereas for RSV B patients, 27.8% were hospitalized (p = 0.07). Around 35.0% of the patients presented risk factors for severity (e.g., prematurity). For those without risk factors, the hospitalization occurred in 47.6% of patients infected with RSV A and in 18.2% infected with RSV B. There was a trend for RSV B infections to be milder than those of RSV A. Even though RSV A-infected patients, including cases without underlying condition and prematurity, were more likely to require hospitalization than those infected by RSV B, the disease severity could not to be attributed to the RSV groups.

Understanding the transmission dynamics of respiratory syncytial virus using multiple time series and nested models.

The nature and role of re-infection and partial immunity are likely to be important determinants of the transmission dynamics of human respiratory syncytial virus (hRSV). We propose a single model structure that captures four possible host responses to infection and subsequent reinfection: partial susceptibility, altered infection duration, reduced infectiousness and temporary immunity (which might be partial). The magnitude of these responses is determined by four homotopy parameters, and by setting some of these parameters to extreme values we generate a set of eight nested, deterministic transmission models. In order to investigate hRSV transmission dynamics, we applied these models to incidence data from eight international locations. Seasonality is included as cyclic variation in transmission. Parameters associated with the natural history of the infection were assumed to be independent of geographic location, while others, such as those associated with seasonality, were assumed location specific. Models incorporating either of the two extreme assumptions for immunity (none or solid and lifelong) were unable to reproduce the observed dynamics. Model fits with either waning or partial immunity to disease or both were visually comparable. The best fitting structure was a lifelong partial immunity to both disease and infection. Observed patterns were reproduced by stochastic simulations using the parameter values estimated from the deterministic models.

The reappearance of Victoria lineage influenza B virus in Brazil, antigenic and molecular analysis.

BACKGROUND: In contrast to influenza A, minor influenza B viruses can co-circulate with the dominant strain during an epidemic allowing the re-emergence of old strains and reassortment between those different strains. The 2001-2002 influenza season in the northern hemisphere was distinguished by the re-emergence of the Victoria-lineage viruses, which replaced the Yamagata-lineage, after being restricted to East Asia throughout the 1990s. OBJECTIVES: To describe the antigenic and genetic characteristics of influenza B viruses detected in South and South East Brazil and determine their lineages. STUDY DESIGN: Influenza samples collected during epidemics between 1999 and 2002 were analyzed by indirect immunofluorescence assay (IFA). Positive results were confirmed through multiplex PCR and isolation in cell culture. Isolated viruses were antigenically characterized by hemagglutination inhibition. Fourteen hemagglutinin (HA) gene sequences obtained in this work were used for phylogenetic analysis. RESULTS: Brazilian isolates from 2002 were associated with the Victoria-lineage, diverging from the vaccine used throughout that influenza season in Brazil. CONCLUSIONS: These results indicate the reappearance of Sichuan/7/97-like samples in South and South East Brazilian Regions simultaneously. They indicate the need for neuraminidase gene evaluation and demonstrate the importance of influenza laboratory surveillance to establish which strains should be included in the influenza vaccine.

Measles virus antigen in macrophage/microglial cells and astrocytes of subacute sclerosing panencephalitis.

In two patients with subacute sclerosing panencephalitis (SSPE) of 10 and 25 months duration we demonstrated by immunohistochemistry the presence of measles-virus nucleocapsid antigen (MVNA) in CD68+ cells and astrocytes of brain tissues. In both cases, CD68+ hematogenous monocyte/ macrophages and perivascular microglial cells (Mphi) were found infiltrating the brain parenchyma, and often partially or completely invested by perivascular reactive astrocytes expressing glial fibrillary acidic protein (GFAP). Mphi with cytoplasmic MVNA were often seen in the Virchow-Robin spaces and in close association with perivascular astrocytes, which often also contained MVNA+ intracytoplasmic inclusions. Reactive astrocytosis was more severe in the patient with long-standing illness, and a correspondingly elevated number of strongly GFAP+ MVNA+ or MVNA- perivascular binucleated astrocytes was observed. An uptake of MVNA+ cell debris by reactive astrocytes was evident in areas of white matter displaying extensive demyelination and necrosis. Taken together, these observations seem to indicate that the brain infiltration by Mphi carrying measles virus could represent one pathway of virus entry and dissemination in the central nervous system. Virus transfer to perivascular astrocytes via cell-to-cell contacts with infected macrophages is also suggested.

Comparison of PCR, enzyme immunoassay and conventional culture for adenovirus detection in bone marrow transplant patients with hemorrhagic cystitis.

BACKGROUND: Adenovirus-associated hemorrhagic cystitis (HC) has become a recognized sequel of immunosuppression. The diagnosis of viral infection is usually determined by viral cultures. OBJECTIVES: Analysis of different diagnostic methods for adenovirus (AdV) detection in bone marrow transplant patients with hemorrhagic cystitis. STUDY DESIGN: We describe a prospective study for AdV detection in the urine of patients with hematuria in the first 100 days after bone marrow transplant (BMT), comparing different laboratory techniques, PCR, enzyme immunoassay (EIA) and conventional culture. RESULTS: A total of 143 urine samples were analyzed, 75 collected in the pre-transplant period with and without hematuria and 68 post-transplant, only with microscopic or macroscopic hematuria. After BMT, hematuria occurred in 38.9% of patients, being more frequent in unrelated donor transplants. AdV was isolated in one pre-transplant patient without symptoms and in three post-transplant patients with HC grades 3 and 4 (severe), who were in month 2 or 3 post-transplant. Compared to culture as the gold standard, the accuracy, specificity and sensitivity of EIA were 95, 30 and 100% and for PCR were 63, 100 and 60%, respectively. CONCLUSIONS: We concluded that despite technical difficulties and the long time that elapsed before results were obtained, cell culture still remains the best method for adenovirus detection in the urine of patients with hemorrhagic cystitis.

IgM antibody capture haemadherence test (MACHAT) for the detection of measles specific IgM.

An antibody capture haemadherence test (MACHAT) for detecting measles-specific IgM is described. The assay is based on the antibody capture principle with rhesus monkey erythrocytes as detector system in place of labelled antisera. MACHAT was compared with a commercial indirect enzyme immunoassay (EIA) for measles-specific IgM using 382 sera from patients notified as measles. There was good agreement between the two tests; 106 sera were found to contain measles IgM by both tests, 7 further sera were positive only in the commercial EIA and 9 only in MACHAT. One sera gave an equivocal result in MACHAT and another in the commercial EIA. Twelve of the 18 sera with discrepant results were also tested by MACRIA; in 7 MACRIA gave the same results as MACHAT, in 3 the MACRIA results agreed with the commercial test and in 2 the MACRIA results were equivocal. Specificity was established by a lack of MACHAT reactivity in sera collected from blood donors (n = 83) and from cases of recent rubella, dengue and parvovirus B19 infection (n = 51). The MACHAT is a simple, cheap test that can be read by eye and is suitable for measles surveillance programmes in the developing world.

In situ hybridization with biotinylated DNA probes: a rapid diagnostic test for adenovirus upper respiratory infections.

Adenovirus DNA was detected in cells from nasopharyngeal secretions of children with acute respiratory infections by in situ hybridization with biotinylated probes. The technique was easy to perform, giving rapid results which were well correlated with those of immunofluorescence assays of the same samples. Adenoviruses of subgroups B, C and E were detected equally well by probes prepared either from purified adenovirus type 5 or from a plasmid (A1) carrying a cloned insertion of BamH1 fragments C and D of adenovirus type 2 in pAT 153. The use of stable non-radioactive probes makes in situ hybridization a feasible assay for use in clinical laboratories with moderate resources.

Salivary diagnosis of measles for surveillance: a clinic-based study in Niterói, state of Rio de Janeiro, Brazil.

This study was designed to investigate whether saliva could be a feasible alternative to serum for the diagnosis of recent measles infection in a clinic setting. Forty-two paired blood and saliva samples collected 1 to 16 days after onset of illness from 29 patients with clinical measles were tested for specific immunoglobulin (Ig) M by antibody-capture radioimmunoassay. Measles IgM was detected in all serum samples and in 39 (92.9%) saliva specimens. Between 1 and 3 weeks after illness onset, virus-specific IgM was detected in 100% of saliva samples. Measles IgM was also detected in 17 saliva specimens, not paired with blood samples, collected from study patients 5 days to 3 weeks after onset. Our results indicate that salivary IgM detection is a suitable non-invasive method for investigation of notified cases under conditions of routine clinic use.

Serological findings during a measles outbreak occurring in a population with high vaccine coverage.

From March 1991 to April 1992, serum samples for IgM detection were collected from 112 clinical measles cases reported to the Health Department of Niterói, State of Rio de Janeiro. The positivity exceeded 90% for specimens collected from the 5th to the 29th day after the onset of the disease. After day 30 a decline in IgM detection was observed, although positivity has been detected up to 90 days after the onset of the symptoms. Forty-four patients (48.9%) with an IgM response had a history of prior measles vaccination. In 5 of the 22 measles-IgM negative cases the infection was due to other agents (rubella: 4 cases, dengue: 1 case). These results show that sensitivity of the test employed for confirming suspected measles cases is high, even in vaccinated patients.

Longitudinal study of acute respiratory diseases in Rio de Janeiro: occurrence of respiratory viruses during four consecutive years.

The occurrence of different viruses in nasopharyngeal secretions from children less than 5 years old with acute respiratory infections (ARI) was investigated over a period of 4 years (1982-1985) in Rio de Janeiro. Of the viruses known to be associated with ARI, all but influenza C and parainfluenza types 1, 2 and 4 were found. Viruses were found more frequently in children attending emergency or pediatric wards than in outpatients. This was clearly related to the high incidence of respiratory syncytial virus (RSV) in the more severe cases of ARI. RSV positive specimens appeared mainly during the fall, over four consecutive years, showing a clear seasonal occurrence of this virus. Emergency wards provide the best source of data for RSV surveillance, showing sharp increase in the number of positive cases coinciding with increased incidence of ARI cases. Adenovirus were the second most frequent viruses isolated and among these serotypes 1, 2 and 7 were predominant. Influenza virus and parainfluenza virus type 3 were next in frequency. Influenza A virus were isolated with equal frequency in outpatient departments, emergency and pediatric wards. Influenza B was more frequent among outpatients. Parainfluenza type 3 caused outbreaks in the shanty-town population annually during the late winter or spring and were isolated mainly from outpatients. Herpesvirus, enterovirus and rhinovirus were found less frequently. Other viruses than RSV and parainfluenza type 3 did not show a clear seasonal incidence.

Measles antibody prevalence after mass immunization campaign in Niterói, state of Rio de Janeiro, Brazil.

Three months after a mass vaccination campaign (coverage: 100%) against measles a random seroepidemiological survey was carried out in students aged 1 to 19 years old in the Municipality of Niterói, State of Rio de Janeiro. Blood samples were tested for measles antibodies by enzyme immunosorbent assay (EIA) and negative cases were tested again using hemagglutination inhibition (HI) and plaque reduction neutralization (PRN). Of the 798 samples tested by EIA, 718 (90.2%) were positive for measles antibodies. PRN test was more sensitive than EIA and HI in detecting measles specific antibodies. The total antibody prevalence increased from 90.2% to 93.2% when HI was employed in EIA negative specimens and to 98.9% when PRN was used. After the mass vaccination campaign a marked decrease in measles incidence was observed in the municipality studied, showing the effectiveness of the strategy used for measles control in developing countries.

Enteroviruses isolated from patients with acute respiratory infections during seven years in Rio de Janeiro (1985-1991).

Enteroviruses were investigated in respiratory secretions collected from patients with acute respiratory infections (ARI) over a seven year period (1985-1991), as part of a longitudinal study of ARI aetiology. All the viruses that are most commonly associated with ARI were found in this study. Among the virus isolates, enteroviruses were only less frequent than respiratory syncytial viruses, adenoviruses and influenzaviruses. Forty five enterovirus samples were isolated from patients with either upper respiratory tract infections (URTI) or lower respiratory tract infections (LRTI). From these enterovirus isolates, thirty one samples were identified as poliovirus (n = 18) and non polio enterovirus (n = 13) by serum neutralization. Poliovirus were identified as type 1 and 2 and all of them were vaccinal strains. From thirteen non polio enterovirus, twelve were identified as echovirus serotypes 1, 2, 7, 11, 19 and 31. The remainder was identified as coxsackievirus B4.

Genomic characterization of adenovirus serotype 7 isolated in Brazil from acute respiratory disease patients during the period from 1980 to 1991.

Forty isolates of adenovirus type 7 were analized by restriction enzyme digestion with BamHI, SmaI, EcoRI and HindIII. These isolates were obtained from acute respiratory disease patients during the years 1980 to 1991. Only two genomic types were found: Ad7b and Ad7e, with Ad7b (87.5%) being more frequent than Ad7e (12.5%). The genomic type Ad7e appeared in the years 1980, 1981 and 1983. Ad7b appeared in 1982 and it was the only genomic type found from 1984 to 1991. Both genomic types were responsible for lower (LRTI) and upper (URTI) respiratory tract infection, but the proportion LRTI/URTI is higher for Ad7b (25/6) than for Ad7e (1/4).

Recent measles viral activity in Uruguai: serological and genetic approaches.

In the summer 1999, a measles outbreak occurred in Uruguai. During this outbreak 58 cases were recorded, 36 of which were laboratory confirmed as positive for measles virus (MV) IgM. The cases occurred in touristic places (Montevideo and Maldonado) predominantly among health facilities and tourist service personnel. Urine specimens collected between days 1 and 4 after the onset of the rash from seven cases were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and nested PCR with primers specific for the carboxyl-terminal region of the nucleoprotein (N) gene. Three of these specimens/cases were positive for MV. Sequencing of 300 nucleotides (nt) of PCR products corresponding to a part of the carboxyl-terminal region of the MV N gene detected in these specimens MV of D6 genotype. The same nucleotide sequences and the same genotype were also previously observed for MV isolates from the 1997 epidemic in Brazil and the 1998 epidemic in Argentina, demonstrating that the D6 genotype was, and may be still circulating in South America.

Genetic characterization of wild-type measles viruses isolated during the 1998 measles epidemic in Argentina.

This study reports on genomic characterization of six measles virus (MV) isolates obtained from a measles epidemic in Argentina in 1998. Reverse transcription-polymerase chain reaction (RT-PCR) and nucleotide sequence analysis of the carboxyl-terminal region of the nucleoprotein (N) gene of these isolates classified all of them as wild type MV of D6 genotype. MVs of D6 genotype with identical nucleotide sequences in the region analyzed were also identified during the 1997 measles epidemic in Brazil and the 1999 measles outbreak in Uruguai. These results suggest that the MVs associated with the 1998 measles epidemic in Argentina might have originated from Brazil. As the D6 genotype is also widely distributed in Europe, it is possible that this genotype was brought to South America from Europe.

Respiratory syncytial virus (RSV) bronchiolitis: comparative study of RSV groups A and B infected children.

The grouping characteristics of 29 respiratory syncytial virus (RSV) present in nasopharyngeal cells collected from hospitalized children with bronchiolitis during the 1990 RSV season in Porto Alegre, RS, were analysed. Twenty-two were grouped as belonging to group A and 7 to group B. Cyanosis, oxygen therapy, cough, length of hospitalization and atelectasis were observed to be more frequently found within group B infected children. Other clinical signs and symptoms were similarly found in both groups.

Human parvovirus B19 infections among exanthematic diseases notified as measles.

A total of 1397 sera collected from 1095 cases of exanthematic disease notified as measles in ES and RJ states during July 1992 to December 1994 were investigated. These sera were first tested for measles and rubella specific IgM. When they proved negative, they were tested for B19 specific IgM by an enzyme immunoassay. B19 infection was confirmed in 27 (2.5%) of these cases. Sera from 194 negative cases for measles and rubella IgM received from other Brazilian states were also investigated and B19 infection was confirmed for 11 of them. Sera from these 38 IgM positive cases for B19, were tested for anti-B19 IgG by an enzyme immunoassay and for B19 DNA by dot blot hybridization. Anti-B19 IgG antibodies were detected in most of the acute sera. B19 DNA was detected in the acute serum of one patient that had been splenectomized before. As the exanthem caused by human parvovirus infection may be clinically diagnosed as rubella, it could be important to diagnose B19 infection in Brazil since it is becoming prevalent as the cause of rash in countries where rubella is controlled by vaccination.

Diagnosis of rubella infection by detecting specific immunoglobulin M antibodies in saliva samples: a clinic-based study in Niterói, RJ, Brazil.

This study was designed to investigate whether saliva could be a feasible alternative to serum for the diagnosis of recent rubella infection in a clinic setting. Forty-five paired blood and saliva samples collected 1 to 29 days after onset of illness were tested for specific immunoglobulin (Ig) M by antibody-capture radioimmunoassay (MACRIA). Rubella IgM was detected in all serum samples and in 38 (84.4%) saliva specimens. Forty-six serum and saliva samples from other patients with rash diseases were tested by MACRIA for control purposes and two saliva specimens were reactive. The saliva test had specificity of 96%. These results indicate that salivary IgM detection may be a convenient non-invasive alternative to serum for investigation of recent rubella cases, especially for disease surveillance and control programmes.

[The joint manifestations of exanthematous viroses]. / Manifestações articulares nas viroses exantemáticas.

The frequency of arthropathy was evaluated in 251 patients with clinical and serological diagnosis (specific IgM detection by enzyme immunoassay) of exanthematous disease. Arthropathy (arthralgia and/or arthritis) was more frequent in dengue fever (49%) and rubella (38.2%) cases than in human parvovirus (30%) and measles (28.1%) cases. Except for measles cases, joint complaints prevailed in adults (> or = 15 years of age) and this difference was significant. The higher frequency of arthropathy in adults was more evident in human parvovirus (75%), rubella (65%) and dengue fever (57.7%) cases than in measles cases (31%). Arthropathy was also more frequent in females for all rash diseases studied. The results of this study showed the high occurrence of joint complaints in the disease described here and the importance of laboratory confirmation for their differential diagnosis.