Little information on the epidemiology and clinical characteristics of human parainfluenza virus (HPIV) infections, especially in children from tropical countries, has been published. The aim of this study was to determine the frequency of HPIV infections in children attended at a large hospital in Fortaleza in Northeast Brazil, and describe seasonal patterns, clinical and epidemiological characteristics of these infections. From January 2001 to December 2006, a total of 3070 nasopharyngeal aspirates collected from children were screened by indirect immunofluorescence for human parainfluenza viruses 1, 2, and 3 (HPIV-1, 2 and 3) and other respiratory viruses. Viral antigens were identified in 933 samples and HPIV in 117. The frequency of HPIV-3, HPIV-1 and HPIV-2 was of 83.76%, 11.96% and 4.27%, respectively. Only HPIV-3 showed a seasonal occurrence, with most cases observed from September to November, and with an inverse relationship to the rainy season. Most HPIV-3 infections seen in outpatients were diagnosed as upper respiratory tract infections.

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.

De janeiro a dezembro de 1998, foram analisados 482 casos de infecção respiratória aguda em crianças atendidas na emergência e nas enfermarias do Centro Pediátrico Professor Hosannah de Oliveira, da Universidade Federal da Bahia, em Salvador. O objetivo deste estudo é conhecer o papel dos vírus na etiologia destas infecções. Secreções nasofaríngeas foram examinadas para detecção viral por imunofluorescência e cultura celular. Vírus foram detectados em 154 casos (31,9%). O vírus sincicial respiratório (VSR) foi o mais prevalente (55,2%), seguido pelos vírus influenza A (17,5%) e parainfluenza 3 (16,2%), adenovírus (7,1%), influenza B (3,8%) e parainfluenza 1 (0,64%). O período epidêmico de VSR foi relacionado à estação de chuvas. Um surto de influenza foi observado nos meses de setembro a novembro. A maioria das infecções foi representada por infecção de trato respiratório superior (63,3%), enquanto que as infecções de trato respiratório inferior foram detectadas em 177 casos (36,7%). Infecções respiratórias agudas virais foram mais freqüentes em crianças até um ano de idade (72,7%).

From January to December 1998, 482 cases of acute respiratory infections in children attended at the emergence or pediatric wards of Centro Pediátrico Professor Hosannah de Oliveira, of Universidade Federal da Bahia, in Salvador (Brazil), were analysed. The aim of this study was to know data about the role of viruses in these infections. Nasopharyngeal secretions were examined for viruses by indirect immunofluorescence and cell culture. Viruses were detected in 154 (31.9%) cases. Respiratory syncytial virus (RSV) was the most prevalent (55.2%), followed by influenza A (17.5%), parainfluenza 3 (16.2%), adenoviruses (7.1%), influenza B (3.8%) and parainfluenza 1 (0.64 %). The epidemic period of RSV was related to the rainy season. One outbreak of influenza was observed from September to November. The majority of the infections were represented by upper respiratory tract infection (63.3%) while lower respiratory tract infections were detected in 177 (36.7%) cases. Viral acute respiratory infections were more frequent in children until one year of age (72.7%).