Virological studies were done in a group of 112 infants under one year of age hospitalized with acute lower respiratory infections and in 41 healthy controls of the same age. Samples of nasopharyngeal aspirates were taken in both groups. Smears for immunofluorescencc of respiratory syncytial virus (RSV), parainfluenza type 3 virus, adenovirus and direct viral isolation technics were performed. Matched samples for serology were also done in 38 cases. Virological studies were positive in 72.3 percent of patients; in 82.7 percent of them RSV was demostrated while in 16.0 percent there were viral associations. The Virological studies in the control group were positive in 36.6 percent of cases for RSV and cytomegalovirus. This results confirms the role of RSV in the etiology of bronchopneumonia in infants under one year of age. (Key woids: respiratory tract infections, pneumonia viral, respiratory syncytial virus, para influenza type 3 virus, adeno viruses).

Studies on the etiology of lower respiratory infectionsAs a contribution to knowledge about the etiology of lower respiratory tract infections (LRI) in infants, 235 patients aged one year or less admitted to a children's hospital at northern metropolitan area of Santiago, Chile along years 1987 throughout 1989 with radiologically confirmed diagnosis were studied. Infants were eligible only if their symptoms lasted for not more than five days and their hospital stay was less than two days. Controls consisted on 74 healthy infants. A search for presumtive etiology was done by means of usual bacteriological procedures {pharyngeal swabs and blood cultures), plus latex test for type b Haemophitus influanzae (Hib) and Streptococcus pneumoniae (SP* in concentrated urine specimens; indirect inmunofluorescence (IF) for specific Chlamydia tracbomatis

Respiratory syncytial virus infection in infants and childrenClinical aspects of respiralory syncytial virus (RSV) infection were studied in 131 infants under age two years who were admited to hospital fof acute lower respiratory tract infection (ALRI) during the cold seasons of year 1988 at Sanliago, Chile. Two daily samples of nasopharyngeal aspirates for RSV inmunofluorescent assay and viral isolation in Hep-2 cell culture, blood cells count and chest X ray were performed at admission. Fifty three of these patients showed positive immunofluorescense for RSV at admission. Nasopharyngeal samples were also ptospectively taken to 251 infants admited (o two hospital rooms at the cold seasons of years 1988 throughout 1989, at admission for viral isolation and immunofluorescent assay and in alternate days for this late assay, along their hospital stays. Nasopharyngeal samples obtained after admission allowed detection of 42 cases of RSV nosocomial infections. No differences were found in clinical, hematologicat and radiological features among patients with and without RSV infections. Nosocomial RSV infection rate was ] 6,7% and 76% of coses occurred in the first week after admission. That rate was not related to intensity of RSV contacts neither lenght of hospital stay. Since there are no known specific differential features between viral and bacterial respiratory infection, rapid methods for viral identification ore highly recommended for better management of acute lower respiratory trocl infections.(Key words: respiratory syncytial viruses, virus diseases, respiratory tract infections, infant.)Las infecciones respiratorias agudas bajas (IRAB) son la causa mas frecuente de hospitalizaci6n en lactantes, especialmente en la estaciones frias, y de muerte de niflos entre un mes y cuatro aflos de edad 1 ' 3 . En Chile los virus respiratorios son la primera causa de IRAB en lactantes y, entre ellos, el virus respiratorio sincicial (VRS) ocupa un rol preponderant, detectandose con frecuencias de 42% a 70%, dependiendo de la forma de estudio 4 " 9 . Estos hallazgos son semejantes a los comunicados en otros pafses 10 -n .La posibilidad de realizar un diagnostico etio16gico rapido ha aumentado al disponer de te*cnicas de inmunofluorescencia 5 -7 ' 9> 12 ' 13 . La detenci6n de VRS en nifios sanos es poco frecuente, por lo que su hallazgo podria implicar un rol patogenico 5 -14 . La mayoria de las infecciones por VRS son de caracter leve, pero algunas comprometen el tracto respiratorio inferior, produciendo bronconeumom'as o bronquiolitis que requicrcn hospitalizacion; ademas, el VRS causa frecuentemente infecciones nosocomiales 7 . Lapresentaci6n de la infecci6n por VRS en forma epidemica todos los inviernos, unida a una semiologi'a ch'nica caracterfstica, podria permitir al pediatra sospechar esta etiologia sin necesidad de recurrir a examenes virologicos, todavia poco accesibles.Este trabajo se hizo con el proposito de describir los aspectos clinicos, radiologicos y de laboratorio general de los lactantes hospitalizados por...

Chlamydia trachomatosis pneumoniaFive infants with Chlamydia trachomatis associated pneumonia are analized. They were diagnosed out of 80 infants admitted to the hospital with pneumonia whose etiology was studied for virus, bacteria and Chlamydia trachomatis. Serum IgM antibodies to Chlamydia tr. were measured by indirect immunofluorescence (IIP), wich is considered to be specific in high titers (1 > 32). The five cases represented 10.4% of infants studied younger than six months. One child was born by cesarean section suggesting the posibility of other non oculogenital still undefined mechanism of transmission. Clinical symptoms and laboratory findings were characteristics of those described in Chlamydia tr. pneumonia. Chlamydia trachomatis must be considered an etiologic agent in infantile pneumonia specially in the first six months of life. The high specificity and sensitivity of the IFF makes this serologic test the best non-invasive method for diagnosis of Chlamydia tr. pneumonia currently available.

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