Surveillance for Respiratory Syncytial Virus in Infants Hospitalized for Acute Lower Respiratory Infection in Chile (1989 to 2000)

Abstract

Hospitalized infants (4,618) were studied for lower respiratory infections from 1989 through 2000 by routine immunofluorescence assay and viral isolation. The hospitalization rate for respiratory syncytial virus (RSV) averaged 2% per year. The fatality rate was 0.1%. Monthly RSV detection varied from 14 to 88%, and epidemics lasted 3.5 to 6 months. From 1994 high-early versus low-late epidemic patterns alternately were observed, the first influenced by a group B strain.Acute respiratory infections are a major worldwide health problem because of associated high morbidity and mortality rates. In Chile acute lower respiratory infections (ALRI) are the primary cause of hospital admissions during infancy. Respiratory syncytial virus (RSV) is the principal cause of ALRI, causing yearly winter epidemics that frequently challenge health resources (3,4,5,9,12,15,21). The expanded use of new techniques has facilitated the local identification of etiologic agents, allowing the comparison of clinical and epidemiological features with biological agent characteristics (2,6,7,14,16,17,19). The aim of this study is to present an overview of RSV infection causing pediatric admissions for ALRI in Chile over a long enough period of time to support recommendations for better clinical and epidemiological management. We present 12 years of data from immunofluorescence assays and isolation for routine viral diagnosis in the pediatric context.A total of 4,618 out of 21,912 children under 2 years of age admitted for ALRI to the Roberto del Rio Children's Hospital, Santiago, Chile, were studied prospectively for RSV from January 1989 to December 2000. Exclusion criteria were prematurity; recurrent wheezing or asthma; and underlying chronic pulmonary, cardiac, or neurological diseases. During the cold season (April to September) two ALRI admissions were randomly selected per day in order to collect 40 to 60 cases per month. During the warm season (October to March) almost all patients were enrolled. For each patient, clinical features, personal and family history of asthma, and the admission diagnosis were obtained from hospital records.Nasopharyngeal aspirates (NPA) were routinely obtained within the first 48 h after admission and were immediately transported to the laboratory for viral isolation and indirect immunofluorescence assay (IFA). Weekday specimens were processed on the same day, but those obtained on weekends were kept at 4°C until processing. Samples were inoculated into HEp-2 and MDCK cells and observed for cytopathic effect (CPE) for 1 week. Confirmatory IFA for RSV, adenovirus, influenza A and B viruses, and parainfluenza viruses 1 to 3 were performed for cultures with and without CPE. Standard IFA was done using monoclonal antibodies provided by L. Anderson, Centers for Disease Control and Prevention (CDC), Atlanta, Ga., and P. Pothier, Dijon, France, as previously described (3, 17). From 1994 to 2000, RSV strains from NPA or positive cultures were grouped by IFA with monoclonal antibodies 133-1H and 93-11C (CDC) and 2B8 ...

Intragroup antigenic diversity of human respiratory syncytial virus (group A) isolated in Argentina and Chile

“…In Chile and Argentina, most studies on HRSV have been based on analyses of epidemiological and clinical aspects of HRSV infections and viral antigenic group typing [Videla et al, 1998;Lagos et al, 1999;Carballal et al, 2000;Imaz et al, 2000;Avendañ o et al, 2003] The main objective of the present study was to examine the antigenic diversity within groups of HRSV strains recovered during consecutive outbreaks in Buenos Aires (Argentina) and Santiago (Chile) from 1995 to 2002. As second objective, we proposed to compare the antigenic patterns of Argentinean and Chilean HRSV strains circulating during the same period (1999)(2000)(2001).…”

“…This study was undertaken as part of a multicenter project that involved different laboratories from South America [Avendañ o et al, 2003;Frabasile et al, 2003;Moura et al, 2004]. The use of an ELISA with MAbs directed against the G glycoprotein of HRSV was chosen as suitable method to evaluate strain diversity, since in our countries is very expensive to perform nucleotide sequencing and genotyping for a large number of strains.…”

Respiratory Syncytial Virus-Associated Hospitalizations in Pre-Mature Infants in Lima, Peru

“…8,14 In South America, especially in the southern part of the continent (i.e., Chile and Argentina), some studies have shown a clear seasonality, with a peak around the fall and winter months (May to August). 5,7 However, in equatorial regions that lack dramatic seasonal temperature variations (i.e., Fortaleza, Brazil), RSV infection may have a peak in the rainy season (January to August). 15 In this study, we were not able to define a clear-cut RSV seasonality.…”

“…It is estimated to cause approximately 33 million new episodes of acute lower respiratory infections in children annually and about 53,000-199,000 deaths annually in young children; 96% of episodes and 99% of deaths occur in developing countries. 1,2 In Latin America, there are several studies on the epidemiology of RSV infections in children [2][3][4][5] ; however, there are limited data on the disease burden of these infections in high-risk groups, such as pre-term infants. 6,7 Prevention of RSV disease relies on infection control and hygiene measures as well as provision of immunoprophylaxis in select infants.…”

Vacuna anti-influenza en niños: Estado del arte

“…Varias publicaciones nacionales concuerdan en demostrar el impacto de la influenza como causa de hospitalización en lactantes sanos 13,[15][16][17][18] . La mayoría de las hospitalizaciones pediátricas ocurren en niños bajo 2 años de edad y alrededor de 60% en lactantes bajo 12 meses, afectando en su gran mayoría (60-75%) a niños sanos, los que no son incluidos en los grupos de riesgo "tradicionales" con indicación de vacuna [15][16][17][18] . Más de 50% presenta complicaciones como sobreinfección bacteriana pulmonar, otitis media aguda (OMA) o insuficiencia respiratoria 15 .…”