Asthma exacerbations in a subtropical area and the role of respiratory viruses: a cross-sectional study.

BACKGROUND: Multiple factors are involved in asthma exacerbations, including environmental exposure and viral infections. We aimed to assess the association between severe asthma exacerbations, acute respiratory viral infections and other potential risk factors. METHODS: Asthmatic children aged 4-14 years were enrolled for a period of 12 months and divided into two groups: those with exacerbated asthma (group 1) and non-exacerbated asthma (group 2). Clinical data were obtained and nasopharyngeal samples were collected through nasopharyngeal aspirate or swab and analysed via indirect fluorescent immunoassays to detect influenza A and B viruses, parainfluenza 1-3, adenovirus and respiratory syncytial virus. Rhinovirus was detected via molecular assays. Potential risk factors for asthma exacerbation were identified in univariate and multivariate analyses. RESULTS: In 153 children (group 1: 92; group 2: 61), median age 7 and 8 years, respectively, the rate of virus detection was 87.7%. There was no difference between groups regarding the frequency of virus detection (p = 0.68); however, group 1 showed a lower frequency (19.2%) of inhaled corticosteroid use (91.4%, p < 0.01) and evidence of inadequate disease control. In the multivariate analysis, the occurrence of three or more visits to the emergency room in the past 12 months (IRR = 1.40; p = 0.04) and nonadherence to inhaled corticosteroid (IRR = 4.87; p < 0.01) were the only factors associated with exacerbation. CONCLUSION: Our results suggest an association between asthma exacerbations, poor disease control and nonadherence to asthma medication, suggesting that viruses may not be the only culprits for asthma exacerbations in this population.

Monitoring the circulation of rotavirus among children after the introduction of the Rotarix™ vaccine in Goiânia, Brazil.

The epidemiological features of rotavirus A (RVA) infection differ between children from developing and developed countries which could result in differences in vaccine efficacy around the world. To evaluate the impact of Rotarix™ on RVA prevalence, we monitored RVA genotypes circulating in Goiânia by monitoring virus in faecal samples from children that had or had not been previously vaccinated. From February-November of 2008, 220 faecal samples were collected from children in seven day-care centres. RVA detection was performed by two methodologies and the results were confirmed by polyacrylamide gel electrophoresis. From the 220 samples, eight were RVA-positive (3.6%) and five were from children that had received either one or two doses of the vaccine. All positive samples were collected from children with diarrhoea during August and September. Genotyping of the RVA characterised five of the viral samples as genotype G2P[4] and one as G8P[4], suggesting that G2P[4] was the predominant circulating genotype in Goiânia during the study. The fact that vaccinated children were also infected by RVA suggests that the vaccine does not fully protect against infection by the G2[P4] RVA genotype.

Epidemiological features of rotavirus infection in Goiânia, Goiás, Brazil, from 1986 to 2000.

A total of 2,605 faecal specimens from children up to 10 years old with or without diarrhoea were collected. Samples were obtained from 1986 to 2000 in hospitals, outpatient clinics and day-care centers in Goiânia, Goiás. Two methodologies for viral detection were utilized: a combined enzyme immunoassay for rotavirus and adenovirus and polyacrylamide gel electrophoresis. Results showed 374 (14.4%) faecal specimens positive for Rotavirus A, most of them collected from hospitalized children. A significant detection rate of rotavirus during the period from April to August, dry season in Goiânia, and different frequencies of viral detection throughout the years of study were also observed. Rotavirus was significantly related to hospitalization and to diarrhoeal illness in children up to 24 months old. This study reinforces the importance of rotavirus as a cause of diarrhoea in children and may be important in regards to the implementation of rotavirus vaccination strategies in our country.

Detection and genotyping of astroviruses from children with acute gastroenteritis from Goiânia, Goiás, Brazil.

BACKGROUND: The astroviruses constitute important agents of childhood diarrhea. The purpose of our research was to detect and genotype astroviruses in fecal samples from children with acute gastroenteritis from Goiânia- Goiás, Brazil. MATERIAL/METHODS: The samples were collected from children up to five years of age with acute gastroenteritis, hospitalized in two public hospitals in Goiânia- Goiás, a city located in the West Central region of Brazil. A total of 516 fecal samples were collected from March 1998 to March 2000. These samples were first screened for rotavirus and adenovirus by an enzyme immunoassay (EIARA) and by PAGE for the detection of rotaviruses. In all samples negative for both viruses (n=351) the presence of astrovirus was investigated by reverse-transcription-polymerase chain reaction (RT-PCR). RESULTS: 2.8% of the samples obtained from children up to two years of age were positive for astrovirus by RT-PCR, with an expected amplicon size of 449 bp. All positive samples, except one, were collected between October and December of 1998, which corresponds to the rainy season in the region (spring/early summer). Nested-PCR genotyping showed that all samples were genotyped and belonged to astrovirus genotype 1, presenting an amplicon band pattern of 212 bp. CONCLUSIONS: This study supports data from the literature about the occurrence of astrovirus in children with acute gastroenteritis. It also helps provide a better understanding of viral etiology in diarrhea.