Isolation and identification of viral agents in Argentinian children with acute lower respiratory tract infection.

From a total population of 1,002 children with acute lower respiratory infection (ALRI), identification of virus was achieved in 304 cases. In this survey, 1,000 nasopharyngeal aspirate and 13 lung tissue samples were tested in four cell lines (HEp-2, MRC-5, MDCK, and LLC-MK2) and by indirect immunofluorescence (IIF), while 242 paired sera were studied by complement fixation. Respiratory syncytial virus (RSV) was the most frequently detected agent (n = 183), followed by adenovirus (n = 28), parainfluenza (n = 5) and 3 (n = 16) viruses, and influenza A (n = 10) and B (n = 4) viruses. The sensitivity and specificity of IIF identification vs. isolation in cell culture were high for RSV (91.5% and 94.9%, respectively). However, IIF proved poorly sensitive for detection of adenovirus (sensitivity, 23.8%; specificity, 100%). The complement-fixation test proved the least effective, with a sensitivity of only 41.5%. Therefore, on the basis of our experience, it appears that the yield for positive diagnosis of virus is increased if both isolation in multiple cell lines and identification by means of IIF are used. Our survey provides for the first time reliable data on the viral etiology of ALRI in Argentina, as determined by three different methods.

[Serologic response measured by complement fixation in children with acute respiratory infection]. / Respuesta serológica medida por fijación de complemento en niños con infección respiratoria aguda.

The aim of this work was to evaluate the sensitivity of complement fixation for serological diagnosis of lower acute respiratory infections (ARI) in small children in comparison with direct methods such as indirect immunofluorescence (IIF) on nasopharyngeal aspirate and tissue culture isolation. Sera from children under 5 year of age with ARI were studied by complement fixation for 6 respiratory viruses (respiratory syncytial virus (RSV), adenovirus, influenza A and B and parainfluenza 1 and 3). In all, 264 pairs of serum samples from children with viral ARI diagnosis (n:135) or from doubtful cases (n:90) were studied. Thirty nine sera were anticomplementary. In samples from confirmed viral ARI patients, seroconversion was detected in 38%, whereas from those with a doubtful diagnosis it was only 14%. Seroconversion for RSV and adenovirus was 39% and 50%, respectively. On correlating seroconversion for the 6 viruses according to age group, 20% positivity was found in the 0-5 month-old group, 35% in the 6-10 month-old and 30% in those over 11 months of age. For RSV alone, 0-5 month-old patients presented 25% seroconversion, and in those over 6 months of age the percentage exceeded 60% (p less than 0.001). Complement fixation test sensitivity vs direct methods (IIF and/or culture) was 38.5%). Our findings confirm the low sensitivity of complement fixation to detect antibodies in ARI, particularly in children under 6 months of age and support the higher efficacy of direct diagnostic methods. However, complement fixation serology is useful for epidemiological studies in children over 6 months of age, since over 60% of RSV were readily detected.

Respuesta serológica medida por fijación de complemento en niños con infección respiratoria aguda. / [Serologic response measured by complement fixation in children with acute respiratory infection]

The aim of this work was to evaluate the sensitivity of complement fixation for serological diagnosis of lower acute respiratory infections (ARI) in small children in comparison with direct methods such as indirect immunofluorescence (IIF) on nasopharyngeal aspirate and tissue culture isolation. Sera from children under 5 year of age with ARI were studied by complement fixation for 6 respiratory viruses (respiratory syncytial virus (RSV), adenovirus, influenza A and B and parainfluenza 1 and 3). In all, 264 pairs of serum samples from children with viral ARI diagnosis (n:135) or from doubtful cases (n:90) were studied. Thirty nine sera were anticomplementary. In samples from confirmed viral ARI patients, seroconversion was detected in 38

, whereas from those with a doubtful diagnosis it was only 14

. Seroconversion for RSV and adenovirus was 39

and 50

, respectively. On correlating seroconversion for the 6 viruses according to age group, 20

positivity was found in the 0-5 month-old group, 35

in the 6-10 month-old and 30

in those over 11 months of age. For RSV alone, 0-5 month-old patients presented 25

seroconversion, and in those over 6 months of age the percentage exceeded 60

(p less than 0.001). Complement fixation test sensitivity vs direct methods (IIF and/or culture) was 38.5

). Our findings confirm the low sensitivity of complement fixation to detect antibodies in ARI, particularly in children under 6 months of age and support the higher efficacy of direct diagnostic methods. However, complement fixation serology is useful for epidemiological studies in children over 6 months of age, since over 60

of RSV were readily detected.

Aplicabilidad de técnicas rápidas de diagnóstico para la identificación de virus sincicial respiratorio y adenovirus / Applicability of rapid techniques for respiratory sincytial virus and adenovirus detection

El objetivo de este estudio fue evaluar la eficacia y aplicabilidad en nuestro medio de tres técnicas de análisis virológico rápido, inmunofluorescencia (IF), enzimo-ensayo (ELISA) y detección de genomas virales para diagnóstico de infección respiratoria causada por virus sincicial respiratorio (VSR) y adenovirus, en comparación con el método de aislamiento en cultivo de tejidos. Entre 1984 y 1988 se estudiaron 1230 aspirados nasofaríngeos (ANF) provenientes de niños menores de 5 años con infección aguda del tracto respiratorio inferior. En los ANF se determinó la presencia de antígenos de VSR y adenovirus por IF indirecta y ELISA y se intentó el aislamiento en cultivo de células Hep-2 y MRC-5 (considerado como método patrón). Para VSR, la especificidad y la sensibilidad de la IF con respecto al aislamiento en cultivo fue de 94,3 por ciento y 87,7 por ciento, respectivamente. Para adenovirus, en cambio se obtuvo una sensibilidad y especificidad del 33,3 por ciento y 99,9 por ciento. Con la técnica de ELISA se obtuvo para VSR una sensibilidad del 96,3 por ciento y una especificidad del 91,5 por ciento y para adenovirus 18,2 por ciento y 99,7 por ciento respectivamente. La técnica de hibridación en punto se desarrolló para su uso experimental en el diagnóstico de infecciones por adenovirus sobre 1002 ANF. La misma demostró tener una alta especificidad (96,5 por ciento) y una buena sensibilidad (85,7 por ciento). El costo estimado del IF fue aproximadamente la mitad que el aislamiento del cultivo. Estos resultados señalan a la IF como técnica de elección para el diagnóstico rápido de VSR, pero no para adenovirus, para el cual el aislamienmto en cultivo y la hibridación resultaron las mejores técnicas. La IF para el diagnóstico rápido para VSR debería ser implementado a nivel asistencial en hospitales pediátricos debido a que es el principal patógeno involucrado en la infección respiratoria aguda de las vías aéreas inferiores en niños menores de 5 años

Aplicabilidad de técnicas rápidas de diagnóstico para la identificación de virus sincicial respiratorio y adenovirus / Applicability of rapid techniques for respiratory sincytial virus and adenovirus detection

El objetivo de este estudio fue evaluar la eficacia y aplicabilidad en nuestro medio de tres técnicas de análisis virológico rápido, inmunofluorescencia (IF), enzimo-ensayo (ELISA) y detección de genomas virales para diagnóstico de infección respiratoria causada por virus sincicial respiratorio (VSR) y adenovirus, en comparación con el método de aislamiento en cultivo de tejidos. Entre 1984 y 1988 se estudiaron 1230 aspirados nasofaríngeos (ANF) provenientes de niños menores de 5 años con infección aguda del tracto respiratorio inferior. En los ANF se determinó la presencia de antígenos de VSR y adenovirus por IF indirecta y ELISA y se intentó el aislamiento en cultivo de células Hep-2 y MRC-5 (considerado como método patrón). Para VSR, la especificidad y la sensibilidad de la IF con respecto al aislamiento en cultivo fue de 94,3 por ciento y 87,7 por ciento, respectivamente. Para adenovirus, en cambio se obtuvo una sensibilidad y especificidad del 33,3 por ciento y 99,9 por ciento. Con la técnica de ELISA se obtuvo para VSR una sensibilidad del 96,3 por ciento y una especificidad del 91,5 por ciento y para adenovirus 18,2 por ciento y 99,7 por ciento respectivamente. La técnica de hibridación en punto se desarrolló para su uso experimental en el diagnóstico de infecciones por adenovirus sobre 1002 ANF. La misma demostró tener una alta especificidad (96,5 por ciento) y una buena sensibilidad (85,7 por ciento). El costo estimado del IF fue aproximadamente la mitad que el aislamiento del cultivo. Estos resultados señalan a la IF como técnica de elección para el diagnóstico rápido de VSR, pero no para adenovirus, para el cual el aislamienmto en cultivo y la hibridación resultaron las mejores técnicas. La IF para el diagnóstico rápido para VSR debería ser implementado a nivel asistencial en hospitales pediátricos debido a que es el principal patógeno involucrado en la infección respiratoria aguda de las vías aéreas inferiores en niños menores de 5 años (AU)

Viral etiology in acute lower respiratory infections in children from a closed community.

The aim of this study was to determine the viral agents associated with acute lower respiratory infections (ALRI) in young children. During a 2-yr period, 204 nasopharyngeal aspirates (NPA) from children under 4 yr of age living in an orphanage and exhibiting febrile ALRI were studied by both indirect immunofluorescence (IIF) and isolation in four cell lines. NPA cell smears as well as tissue culture cells exhibiting cytopathic effect (CPE) or hemadsorption were stained by IIF for respiratory syncytial virus (RSV), adenovirus, influenza A and B, and parainfluenza 1 and 3. Viral etiology was demonstrated in 21.2% of acute respiratory infection cases. The most frequently detected virus was RSV (53.5% of viral positive diagnoses), followed by unidentified viruses (18.6%), adenovirus (13.9%), influenza A (7%), and parainfluenza 3 (4.7%). The most common clinical entities were: bronchitis, 46.1%; pneumonia, 24%; bronchiolitis, 22%; and multifocal pneumonia, 8%. Malnourishment was found in 56% of children with ALRI, whereas 50% was found among total orphanage population. The 3 to 8-month-old age group accounted for half of all ALRI cases. Viral etiology was shown for 26.5% of patients with pneumonia, 22% with bronchitis, and 16% with bronchiolitis. RSV and adenovirus occurred in fall and winter, while parainfluenza 3 was detected in early spring. In the two fatal cases observed, histologic lesions were compatible with adenovirus infection, but this virus could be isolated from the lung in only one case.