Occurrence and severity of infections caused by subgroup A and B respiratory syncytial virus in children in southeast Brazil

An amplicon-based protocol for whole-genome sequencing of human respiratory syncytial virus subgroup A

It is convenient to study complete genome sequences of human respiratory syncytial virus (hRSV) for ongoing genomic characterization and identification of highly transmissible or pathogenic variants. Whole genome sequencing of hRSV has been challenging from respiratory tract specimens with low viral loads. Herein, we describe an amplicon-based protocol for whole genome sequencing of hRSV subgroup A validated with 24 isolates from nasopharyngeal swabs and infected cell cultures, which showed cycle threshold (Ct) values ranging from 10 to 31, as determined by quantitative reverse-transcription polymerase chain reaction. MinION nanopore generated 3200 to 5400 reads per sample to sequence over 93% of the hRSV-A genome. Coverage of each contig ranged from 130× to 200×. Samples with Ct values of 20.9, 25.2, 27.1, 27.7, 28.2, 28.8, and 29.6 led to the sequencing of over 99.0% of the virus genome, indicating high genome coverage even at high Ct values. This protocol enables the identification of hRSV subgroup A genotypes, as primers were designed to target highly conserved regions. Consequently, it holds potential for application in molecular epidemiology and surveillance of this hRSV subgroup.

Respiratory Syncytial Virus Disease Severity in Young Children

BACKGROUND

Respiratory syncytial virus (RSV) is the leading cause of acute respiratory infections (ARI) in hospitalized children. Although prematurity and underlying medical conditions are known risk factors, most of these children are healthy, and factors including RSV load and subgroups may contribute to RSV-ARI severity. Therefore, we aimed to evaluate the role of RSV in ARI disease severity and determine factors associated with increased RSV-ARI severity in young children.

METHOD

Children less than five years with fever and/or ARI symptoms were recruited from the emergency department (ED) or inpatient settings at Vanderbilt Children's Hospital. Nasal and/or throat swabs were tested by qRT-PCR for common respiratory viruses, including RSV. A severity score was calculated for RSV-positive children.

RESULTS

From 11/2015 through 07/2016, 898 participants were enrolled, and 681 (76%) had at least one virus detected, with 191 (28%) testing positive for RSV. RSV-positive children were more likely to be hospitalized, require intensive care unit (ICU) admission, and receive oxygen compared to other-virus-positive children. Higher viral load, White race, younger age, and higher severity score were independently associated with hospitalization in RSV-positive children. No differences in disease severity were noted among children infected with RSV A and B.

CONCLUSION

RSV was associated with increased ARI severity in young children enrolled from ED and inpatient settings, but no differences in disease severity were noted between RSV A and B. . These findings emphasize the need for effective antiviral therapy and/or preventive measures such as vaccines against RSV in young children.

Human coronavirus alone or in co-infection with rhinovirus C is a risk factor for severe respiratory disease and admission to the pediatric intensive care unit: A one-year study in Southeast Brazil

Objective

We aimed to assess the profile of respiratory viruses in young children hospitalized for acute lower respiratory tract infection (ALRI) and its association with disease severity, defined as need for pediatric intensive care unit (PICU) admission.

Design

Prospective observational cohort study.

Setting

A tertiary-care university hospital in Brazil.

Patients

Children younger than three years attending the pediatric emergency room with ALRI who were admitted to the hospital.

Interventions

None.

Measurements and main results

Nasopharyngeal aspirates were collected from patients from June 1^st, 2008 to May 31^st, 2009within the first 48 hours of hospitalization. Nasopharyngeal aspirates were tested for 17humanrespiratory viruses by molecular and immunofluorescence based assays. Simple and multiple log-binomial regression models were constructed to assess associations of virus type with a need for PICU admission. Age, prematurity, the presence of an underlying disease and congenital heart disease were covariates. Nasopharyngeal aspirates were positive for at least one virus in 236 patients. Rhinoviruses were detected in 85.6% of samples, with a preponderance of rhinovirus C (RV-C) (61.9%). Respiratory syncytial virus was detected in 59.8% and human coronavirus (HCoV) in 11% of the samples. Co-detections of two to five viruses were found in 78% of the patients. The detection of HCoV alone (adjusted relative risk (RR) 2.18; 95% CI 1.15–4.15) or in co-infection with RV-C (adjusted RR 2.37; 95% CI 1.23–4.58) was independently associated with PICU admission.

Conclusions

The detection of HCoV alone or in co-infection with RV-C was independently associated with PICU admission in young children hospitalized for ALRI.

[Assessment of the program for use of the monoclonal antibody palivizumab in São Paulo State, Brazil]

This study aimed to assess the program for use of the monoclonal antibody palivizumab in São Paulo State, Brazil. The evaluation adopted the frame of reference proposed by Donabedian, and the data were discussed on the basis of the guidelines from the Ruling on the use of palivizumab in the national network and in the Manual on Standards and Procedures for Vaccination. Sixteen application services in the state were included, with 693 children/mothers enrolled in the program in 2014 (85.1% of the eligible population). For the structure and process evaluation, scores were created that allowed classifying the application services as adequate, partially adequate, and inadequate (non-compliance rates were ≤ 10%, 11-20%, and > 20%, respectively). Results were evaluated according to the association between failure to administer palivizumab and need for hospitalization due to respiratory disease/symptoms, based on the point and interval odds ratios, with 95% confidence interval and critical p-value < 0.05. Of the 11 application services whose structure was classified as adequate, only two showed adequate process, four showed inadequate process, and five partially adequate process. Risk of ICU admission due to respiratory disease/symptoms increased on average by 30% for each failure (p = 0.003; OR = 1.30; 95%CI: 1.09-1.55). In conclusion, having a favorable structure for the program for use of palivizumab in São Paulo State did not necessarily result in an adequate process. In general, the situation with the structure was better than the process. All doses of the monoclonal antibody need to be administered in order to prevent hospitalization from respiratory disease/symptoms.

Relative frequency, Possible Risk Factors, Viral Codetection Rates, and Seasonality of Respiratory Syncytial Virus Among Children With Lower Respiratory Tract Infection in Northeastern Brazil

Few studies, each limited to a single major city, have investigated the prevalence and seasonal patterns of different viruses among children with low respiratory tract infections (LRTI) in Northeastern Brazil. The aim of this study was to determine the frequency of respiratory syncytial virus (RSV) and of 7 other viruses in children for LRTI in 4 capitals from this region, and investigate their association with several risk factors, including meteorological data. From April 2012 to March 2013, 507 children, aged up to 24 months and hospitalized with LRTI in one of the participating centers at Aracajú, Salvador, Recife, and Maceió, had a sample of nasopharyngeal aspirate collected and analyzed for the following viruses by reverse-transcription polymerase chain reaction followed by hybridization on low-density microarrays: RSV, influenza, parainfluenza, adenovirus, rhinovirus, metapneumovirus, bocavirus, and coronavirus. The result was positive in 66.5% of cases, RSV was the most common virus (40.2%). Except for rhinovirus (17%), all other virus had frequency rates lower than 6%. Viral coinfections were detected in 13.8% of samples. Possible related risk factors for RSV infection were low age upon entry, attendance of daycare, low gestational age, and low educational level of the father. The relative frequency of viral infections was associated with increasing temperature and decreasing humidity separately, but the results also suggested both associated with increased frequency of RSV. Some of these findings differ from those reported for other regions in Brazil and may be used to guide policies that address LRTI.

Respiratory viruses are continuously detected in children with chronic tonsillitis throughout the year

OBJECTIVE

To evaluate the oscillations on the viral detection in adenotonsillar tissues from patients with chronic adenotonsillar diseases as an indicia of the presence of persistent viral infections or acute subclinical infections.

STUDY DESIGN

Cross-sectional prospective study.

SETTING

Tertiary hospital.

METHODS

The fluctuations of respiratory virus detection were compared to the major climatic variables during a two-year period using adenoids and palatine tonsils from 172 children with adenotonsillar hypertrophy and clinical evidence of obstructive sleep apnoea syndrome or recurrent adenotonsillitis, without symptoms of acute respiratory infection (ARI), by TaqMan real-time PCR.

RESULTS

The rate of detection of at least one respiratory virus in adenotonsillar tissue was 87%. The most frequently detected viruses were human adenovirus in 52.8%, human enterovirus in 47.2%, human rhinovirus in 33.8%, human bocavirus in 31.1%, human metapneumovirus in 18.3% and human respiratory syncytial virus in 17.2%. Although increased detection of human enterovirus occurred in summer/autumn months, and there were summer nadirs of human respiratory syncytial virus in both years of the study, there was no obvious viral seasonality in contrast to reports with ARI patients in many regions of the world.

CONCLUSION

Respiratory viruses are continuously highly detected during whole year, and without any clinical symptomatology, indicating that viral genome of some virus can persist in lymphoepithelial tissues of the upper respiratory tract.

The burden of single virus and viral coinfections on severe lower respiratory tract infections among preterm infants: a prospective birth cohort study in Brazil

BACKGROUND

Respiratory syncytial virus (RSV) is associated with severe lower respiratory tract infection (LRTI), especially in preterm infants. Other viruses, co-detected with RSV, may play a role in the severity of respiratory outcomes.

METHODS

This prospective epidemiologic study of severe LRTI incidence among children born ≤35 weeks gestational age at 3 sites in Brazil (2008-2010) followed a birth cohort for 1 year post-enrollment. Nasal washes from subjects with LRTI were tested for respiratory viruses using polymerase chain reaction. The primary outcome was the incidence of severe LRTI requiring hospitalization associated with RSV infection. Secondary outcomes included identification of viruses associated with LRTI, alone or coinfections, and risk factors associated with severe LRTI.

RESULTS

Among 303 subjects, 176 (58.1%) experienced LRTI. Among these subjects, 162 had samples tested using polymerase chain reaction; 27.8% (45/162) experienced severe LRTI. More subjects with severe LRTI were infected with RSV (30/45, 66.7%) than with other viruses. RSV was present in 33.1% (143/432) of LRTI events tested, 57.3% (82/143) were coinfections. RSV was the virus most frequently associated with severe LRTIs (34/56 events, 60.7%); 50% (17/34 events) single and 50% coinfections. Significantly longer hospital stays were associated with LRTI events involving RSV coinfections compared with RSV single infections (P = 0.012). Infants with severe LRTIs had significantly lower mean RSV-IgG levels at study entry compared with those with nonsevere or no LRTIs (P < 0.05).

CONCLUSIONS

This study confirms the association of RSV alone or as a coinfection with severe LRTI and reinforces the importance of providing adequate prophylaxis for susceptible infants.

Concurrent detection of other respiratory viruses in children shedding viable human respiratory syncytial virus

Human respiratory syncytial virus (HRSV) is an important cause of respiratory disease. The majority of studies addressing the importance of virus co‐infections to the HRSV‐disease have been based on the detection of HRSV by RT‐PCR, which may not distinguish current replication from prolonged shedding of remnant RNA from previous HRSV infections. To assess whether co‐detections of other common respiratory viruses are associated with increased severity of HRSV illnesses from patients who were shedding viable‐HRSV, nasopharyngeal aspirates from children younger than 5 years who sought medical care for respiratory infections in Ribeirão Preto (Brazil) were tested for HRSV by immunofluorescence, RT‐PCR and virus isolation in cell culture. All samples with viable‐HRSV were tested further by PCR for other respiratory viruses. HRSV‐disease severity was assessed by a clinical score scale. A total of 266 samples from 247 children were collected and 111 (42%) were HRSV‐positive. HRSV was isolated from 70 (63%), and 52 (74%) of them were positive for at least one additional virus. HRSV‐positive diseases were more severe than HRSV‐negative ones, but there was no difference in disease severity between patients with viable‐HRSV and those HRSV‐positives by RT‐PCR. Co‐detection of other viruses did not correlate with increased disease severity. HRSV isolation in cell culture does not seem to be superior to RT‐PCR to distinguish infections associated with HRSV replication in studies of clinical impact of HRSV. A high rate of co‐detection of other respiratory viruses was found in samples with viable‐HRSV, but this was not associated with more severe HRSV infection. J Med. Virol. 85:1852–1859, 2013. © 2013 Wiley Periodicals, Inc.

Shift in the timing of respiratory syncytial virus circulation in a subtropical megalopolis: implications for immunoprophylaxis

Respiratory syncytial virus (RSV) is the most common cause of severe respiratory infections worldwide, and an important cause of childhood bronchiolitis, pneumonia, and mortality. Although prevention of RSV infection by immunoprophylaxis with palivizumab has proved effective, a precise understanding of the timing of RSV outbreaks is necessary to ensure that infants are protected when RSV is circulating. In this study a consistent shift in the seasonal patterns of RSV circulation in southeast Brazil (São Paulo) is reported based on the analysis of 15 years of viral surveillance. Surveillance was conducted from 1996 to 2010 and involved the collection of samples from children with symptoms of acute respiratory infection. Putative changes in school terms, in the proportion of RSV genotypes infecting children and in the seasonal dynamics of several climatic parameters during the period were also investigated. The results revealed a progression in the timing of RSV seasons, with a shift in the onset and peak of RSV epidemics from 2007 onwards. Although lower rainfall and temperatures were associated with the onset of outbreaks, there was no evidence of changes in climate, school terms or in the relative proportion of genotypes in the period analyzed. These findings have direct implications for improving the prophylactic use of palivizumab, and stress the importance of fine tuning prophylaxis with recent surveillance data. In the case of São Paulo, palivizumab prophylaxis should be initiated earlier than suggested currently. Similar adjustments may be necessary in other regions.

Diversity and adaptation of human respiratory syncytial virus genotypes circulating in two distinct communities: public hospital and day care center

HRSV is one of the most important pathogens causing acute respiratory tract diseases as bronchiolitis and pneumonia among infants. HRSV was isolated from two distinct communities, a public day care center and a public hospital in São José do Rio Preto - SP, Brazil. We obtained partial sequences from G gene that were used on phylogenetic and selection pressure analysis. HRSV accounted for 29% of respiratory infections in hospitalized children and 7.7% in day care center children. On phylogenetic analysis of 60 HRSV strains, 48 (80%) clustered within or adjacent to the GA1 genotype; GA5, NA1, NA2, BA-IV and SAB1 were also observed. SJRP GA1 strains presented variations among deduced amino acids composition and lost the potential O-glycosilation site at amino acid position 295, nevertheless this resulted in an insertion of two potential O-glycosilation sites at positions 296 and 297. Furthermore, a potential O-glycosilation site insertion, at position 293, was only observed for hospital strains. Using SLAC and MEME methods, only amino acid 274 was identified to be under positive selection. This is the first report on HRSV circulation and genotypes classification derived from a day care center community in Brazil.

Seasonality of viral respiratory infections in southeast of Brazil: the influence of temperature and air humidity

Viruses are the major cause of lower respiratory tract infections in childhood and the main viruses involved are Human Respiratory Syncytial Virus (HRSV), Human Metapneumovirus (HMPV), Influenzavirus A and B (FLUA and FLUB), Human Parainfluenza Virus 1, 2 and 3 (HPIV1, 2 and 3) and Human Rhinovirus (HRV). The purposes of this study were to detect respiratory viruses in hospitalized children younger than six years and identify the influence of temperature and relative air humidity on the detected viruses. Samples of nasopharyngeal washes were collected from hospitalized children between May/2004 and September/2005. Methods of viral detection were RT-PCR, PCR and HRV amplicons were confirmed by hybridization. Results showed 54% (148/272) of viral positivity. HRSV was detected in 29% (79/272) of the samples; HRV in 23.1% (63/272); HPIV3 in 5.1% (14/272); HMPV in 3.3% (9/272); HPIV1 in 2.9% (8/272); FLUB in 1.4% (4/272), FLUA in 1.1% (3/272), and HPIV2 in 0.3% (1/272). The highest detection rates occurred mainly in the spring 2004 and in the autumn 2005. It was observed that viral respiratory infections tend to increase as the relative air humidity decreases, showing significant association with monthly averages of minimal temperature and minimal relative air humidity. In conclusion, viral respiratory infections vary according to temperature and relative air humidity and viral respiratory infections present major incidences it coldest and driest periods.

Molecular and demographic analysis of respiratory syncytial virus infection in patients admitted to King Chulalongkorn Memorial Hospital, Thailand, 2007

Please cite this paper as: Boonyasuppayakorn et al. (2010) Molecular and demographic analysis of respiratory syncytial virus infection in King Chulalongkorn Memorial Hospital admitted patients, Thailand, 2007. Influenza and Other Respiratory Viruses 4(5), 313–323.

Objectives:  To preliminary preview the molecular character and its possible clinical correlation of RSV subgroups in Thailand.

Design:  Cross‐sectional analytic design.

Setting:  Admitted acute lower respiratory tract infection patients of King Chulalongkorn Memorial Hospital, Bangkok, during Jun–Dec, 2007 were recruited.

Sample:  Nasopharyngeal aspirations were collected.

Main outcome measures:  All samples were analyzed for the presence of RSV glycoprotein G gene by reverse transcription PCR. Molecular character of each subgroup was determined by sequencing. Admission records were also analyzed for clinical correlations.

Results:  Equal infectivity and severity of both RSV subgroups to the patients was shown. Mixed infection was shown to be as common as each single infection, higher than previously reported. GA2 of subgroup A and BA‐IV of subgroup B were the most widespread genotypes and showed their monophyletic origins. From admission records, either type of infection did not show significantly preference in demographic record or clinical severity. Comorbidity, however, was statistically significant that more congenital heart disease was found in negative RSV cases, while more chronic pulmonary disease was in positive cases. Nevertheless, the clinical severity was insignificantly different suggesting that only patients with chronic pulmonary underlying were prone to be infected with RSV.

Conclusions:  This preliminary RSV study showed prevalence of subgroups, types of infection, and common genotypes in an epidemic, uncorrelated to demography or clinical severity.

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.

Acute respiratory infection and influenza-like illness viral etiologies in Brazilian adults

Influenza-like illness (ILI) definitions have been used worldwide for influenza surveillance. These different case definitions can vary with regard to sensitivity and predictive values for laboratory confirmed influenza. The literature has indicated the inclusion of other viruses may be the cause of these variable results. The objective of the study was to evaluate ILI national sentinel criteria and viral etiologies in adults diagnosed with acute respiratory infection (ARI) and/or ILI from 2001 to 2003 in Sao Paulo, Brazil. Clinical and laboratory evaluations were observed from 420 adults and collected on a daily basis from outpatient care units at University Hospital. The ILI definition included: fever plus at least one respiratory symptom (cough and/or sore throat) and one constitutional symptom (headache, malaise, myalgia, sweat or chills, or fatigue). DFA and RT-PCR for influenza, parainfluenza, respiratory syncytial virus, adenovirus, enterovirus, coronavirus, rhinovirus, and metapneumovirus were performed on nasal washes and 61.8% resulted positive. The respiratory viruses detected most often were influenza and rhinovirus. ILI was reported for 240/420 patients (57.1%), with influenza and rhinovirus etiologies accounting for 30.9% and 19.6%, respectively. Rhinovirus peak activity was concurrent with the influenza season. These findings highlight the implications of other viruses in ILI etiology and suggest that during the influenza season, this clinical overlap must be considered in the diagnosis and clinical management of patients.

Comparison of direct immunofluorescence, conventional cell culture and polymerase chain reaction techniques for detecting respiratory syncytial virus in nasopharyngeal aspirates from infants

A total of 316 samples of nasopharyngeal aspirate from infants up to two years of age with acute respiratory-tract illnesses were processed for detection of respiratory syncytial virus (RSV) using three different techniques: viral isolation, direct immunofluorescence, and PCR. Of the samples, 36 (11.4%) were positive for RSV, considering the three techniques. PCR was the most sensitive technique, providing positive findings in 35/316 (11.1%) of the samples, followed by direct immunofluorescence (25/316, 7.9%) and viral isolation (20/315, 6.3%) (p < 0.001). A sample was positive by immunofluorescence and negative by PCR, and 11 (31.4%) were positive only by RT-PCR. We conclude that RT-PCR is more sensitive than IF and viral isolation to detect RSV in nasopharyngeal aspirate specimens in newborn and infants.

Oxigenoterapia inalatória em pacientes pediátricos internados em hospital universitário

OBJETIVO: Avaliar o uso da oxigenoterapia inalatória em crianças internadas em hospital universitário. MÉTODOS: Estudo prospectivo de crianças atendidas no Pronto-Socorro Pediátrico do Hospital das Clínicas da Faculdade de Medicina de Botucatu e que receberam oxigenoterapia durante a internação, de maio a setembro de 2005. Indicou-se oxigenoterapia se saturação de oxigênio inferior a 90% e frequência respiratória elevada para idade. Crianças em uso crônico de oxigênio ou com necessidade de ventilação mecânica foram excluídas. Foram avaliados: sintomas respiratórios, diagnósticos clínicos, saturação de oxigênio, método e tempo de oxigenoterapia e responsável pela prescrição. RESULTADOS: Foram atendidas 8.709 crianças no pronto-socorro, sendo que 2.769 (32%) apresentaram doenças respiratórias e 97 necessitaram de internação na enfermaria. Destas, 62 (64%) receberam oxigenoterapia. Das 62 crianças, 37 eram do sexo masculino e a idade variou de 2 meses a 14 anos (mediana: 8 meses). A causa de hipóxia foi pneumonia em 52 crianças (84%), asma em cinco, bronquiolite em quatro e traqueomalácia em uma. As prescrições de oxigenoterapia foram feitas por médicos, com monitoração de saturação de oxigênio por oxímetro de pulso. O tempo mediano de administração de O2 foi 6 dias e o cateter nasal foi usado em 94% dos casos, sendo raro o uso de máscaras ou capuz de oxigênio. CONCLUSÕES: A oxigenoterapia inalatória foi mais frequente em crianças com menor idade e em pacientes com pneumonia, sendo sua indicação compatível com critérios internacionais. O uso do cateter nasal mostrou-se seguro, simples, efetivo e de baixo custo.

Respiratory viruses in children younger than five years old with acute respiratory disease from 2001 to 2004 in Uberlândia, MG, Brazil

The main viruses involved in acute respiratory diseases among children are: respiratory syncytial virus (RSV), influenzavirus (FLU), parainfluenzavirus (PIV), adenovirus (AdV), human rhinovirus (HRV), and the human metapneumovirus (hMPV). The purpose of the present study was to identify respiratory viruses that affected children younger than five years old in Uberlândia, Midwestern Brazil. Nasopharyngeal aspirates from 379 children attended at Hospital de Clínicas (HC/UFU), from 2001 to 2004, with acute respiratory disease, were collected and tested by immunofluorescence assay (IFA) to detect RSV, FLU A and B, PIV 1, 2, and 3 and AdV, and RT-PCR to detect HRV. RSV was detected in 26.4% (100/379) of samples, FLU A and B in 9.5% (36/379), PIV 1, 2 and 3 in 6.3% (24/379) and AdV in 3.7% (14/379). HRV were detected in 29.6% (112/379) of the negative and indeterminate samples tested by IFI. RSV, particularly among children less than six months of life, and HRV cases showed highest incidence. Negative samples by both IFA and RT-PCR might reflect the presence of other pathogens, such as hMPV, coronavirus, and bacteria. Laboratorial diagnosis constituted an essential instrument to determine the incidence of the most common viruses in respiratory infections among children in this region.

Infecções do trato respiratório inferior pelo vírus sincicial respiratório em crianças hospitalizadas menores de um ano de idade

Analisou-se características clínicas e evolutivas em crianças menores de um ano internadas com infecção do trato respiratório inferior por vírus sincicial respiratório (VSR). Feito estudo transversal com 89 lactentes hospitalizados durante as épocas de maior incidência do VSR, em 1997 e 1998, na cidade do Rio de Janeiro. Foram pesquisados antígenos virais, nas secreções de nasofaringe, com anticorpos monoclonais anti-VSR, antiinfluenza A e B e antiparainfluenza tipo 3, por ensaio de imunofluorescência indireta. Formaram-se três grupos: bronquiolite ou bronquite sibilante (n=44), pneumonia (n=26) e bronquiolite e pneumonia (n=19). Houve positividade para o VSR em 42 (47,1%) pacientes. Em 1997 a média de dias de oxigenoterapia foi de 5,2 e em 1998, de 2,5 dias (p> 0,05). Não houve diferença de apresentação clínica entre os lactentes que apresentaram positividade para o VSR e aqueles cujo resultado foi negativo. A sensibilidade e especificidade da sibilância em relação ao isolamento de VSR foram 85% e 65%, respectivamente. O VSR foi o principal causador de infeções do trato respiratório inferior em lactentes que necessitaram de hospitalização.

Genetic diversity of respiratory syncytial virus isolated during an epidemic period from children of northeastern Brazil

Outbreaks of human respiratory syncytial virus (HRSV) are the leading cause of serious acute lower respiratory viral disease in many countries in different continents. Data on clinical and epidemiological aspects of HRSV infections in this country have been reported, but there is lack of data regarding the molecular epidemiology of this virus in Salvador. The genetic variability of HRSV isolated during an outbreak in Salvador, Brazil (1999) has been analysed. Partial sequences of the G protein gene of 13 isolates from antigenic group A and 4 isolates from antigenic group B of HRSV were determined. Nucleotide sequences of C-terminal G gene were compared to sequences of HRSV isolates from countries of South America and from the rest of the world available at the GenBank. Brazilian group A and B isolates were clustered into previously characterised genotypes: GA5, GA2, GA7, and GB3, SAB3, respectively. This is the first study of GA7 and SAB3 genotypes circulation in South American countries. It is interesting to point out that viruses isolated in Salvador appear to be closer related with those from Montevideo-Uruguay and Buenos Aires, Argentina strains, suggesting circulation of similar strains among different South American countries in different seasons. Moreover, viruses closely related genetically circulated in the same year in Salvador and distant places such as Mozambique, supporting the previous suggestion on the complexity of HRSV strain circulation patterns, and the high capability of HRSV spreading world-wide.

Risk factors for wheezing in a subtropical environment: role of respiratory viruses and allergen sensitization

Background

Risk factors for acute wheezing among children in subtropical areas are largely unknown.

Objective

To investigate the role of viral infections, allergen sensitization, and exposure to indoor allergens as risk factors for acute wheezing in children 0 to 12 years old.

Methods

One hundred thirty-two children 0 to 12 years of age who sought emergency department care for wheezing and 65 children with no history of wheezing were enrolled in this case-control study. Detection of respiratory syncytial virus antigen, rhinovirus and coronavirus RNA, adenovirus, influenza, and parainfluenza antigens was performed in nasal washes. Total IgE and specific IgE to mites, cockroach, cat, and dog were measured with the CAP system. Major allergens from mites, cockroach, cat, and dog were quantified in dust samples by ELISA. Univariate and multivariate analyses were performed by logistic regression.

Results

In children under 2 years of age, infection with respiratory viruses and family history of allergy were independently associated with wheezing (odds ratio, 15.5 and 4.2; P = .0001 and P = .008, respectively). Among children 2 to 12 years old, sensitization to inhalant allergens was the major risk factor for wheezing (odds ratio, 2.7; P = .03). High-level allergen exposure, exposure to tobacco smoke, and lack of breast-feeding showed no association with wheezing.

Conclusions

Some risk factors for wheezing previously identified in temperate climates were present in a subtropical area, including respiratory syncytial virus infection in infants and allergy in children older than 2 years. Rhinovirus was not associated with wheezing and did not appear to be a trigger for asthma exacerbations.

Respiratory syncytial virus infections during an epidemic period in Salvador, Brazil. Viral antigenic group analysis and description of clinical and epidemiological aspects

Acute respiratory infections (ARI) caused by respiratory syncytial virus (RSV) were studied in 482 children from Salvador, BA, Brazil, over a period of 12 months. The epidemic period of RSV infections in Salvador occurred from February (summer) to August (winter), with peaks in May, June, and July. The grouping characteristics of 84 RSV present in nasopharyngeal secretions of children seen at a reference university hospital were analyzed. RSV represented 17.4% of all cases and 54.5% of the positive samples. Sixty-four RSV strains were assigned to group A and 14 to group B. Both groups circulated in the five months of the epidemic period studied. Infections by both groups of RSV were more frequent in children up to one year of age. The incidence of RSV ARI was slightly more frequent in males, although group B had more infected females.

Respiratory syncytial virus epidemics: the ups and downs of a seasonal virus

Respiratory syncytial virus (RSV) is the most common pathogen causing lower respiratory tract infections in infants worldwide. Lower respiratory tract infections caused by RSV occur epidemically, and the appearance of epidemics seems to vary with latitude, altitude and climate. This study uses a review of the literature on RSV seasonality to investigate whether a global pattern in RSV epidemics can be found. A comparison of morbidity and mortality caused by RSV in developed vs. developing countries is also presented. The seasons in which RSV epidemics occur typically depend on geographic location and altitude. During these seasons the epidemics tend to appear in clusters. Although the appearance pattern of these epidemics varies from one continent to another, they usually begin in coastal areas. RSV is the cause of one-fifth of lower respiratory infections worldwide. Generally RSV mortality is low, with a median value of zero. However, RSV mortality in developing countries is significantly higher than RSV mortality in developed countries.

Low mortality rates related to respiratory virus infections after bone marrow transplantation

Respiratory viruses (RVs) frequently cause severe respiratory disease in bone marrrow transplant (BMT) recipients. To evaluate the frequency of RV, nasal washes were collected year-round from BMT recipients with symptoms of upper respiratory tract infection (URI). Direct immunofluorescence assay was performed for respiratory syncytial virus (RSV), influenza (Flu) A and B, adenovirus and parainfluenza (Paraflu) virus. Patients with RSV pneumonia or with upper RSV infection, but considered at high risk for developing RSV pneumonia received aerosolized ribavirin. Oseltamivir was given to patients with influenza. A total of 179 patients had 392 episodes of URI. In all, 68 (38%) tested positive: RSV was detected in 18 patients (26.4%), Flu B in 17 (25%), Flu A in 11 (16.2%) and Paraflu in 7 (10.3%). A total of 14 patients (20.6%) had multiple RV infections or coinfection. RSV pneumonia developed in 55.5% of the patients with RSV-URI. One of the 15 patients (6.6%) with RSV pneumonia died. Influenza pneumonia was diagnosed in three patients (7.3%). RSV and influenza infections peaked in fall-winter and winter-spring months, respectively. We observed decreased rates of influenza and parainfluenza pneumonia and low mortality because of RSV pneumonia. The role of antiviral interventions such as aerosolized ribavirin and new neuraminidase inhibitors remains to be defined in randomized trials.