Control externo de la calidad del diagnóstico serológico del dengue en laboratorios de países de las Américas, 1996-2001 / Quality control of the serological diagnosis of dengue in laboratories throughout the Americas, 1996-2001

Dar a conocer los resultados de cuatro controles externos de la calidad del diagnóstico serológico del dengue realizados en la Región de las Américas en el período de 1996- 2001 y presentar los resultados obtenidos por los laboratorios participantes. MÉTODOS: Se realizaron controles externos de la calidad del diagnóstico serológico del dengue en 1996-1997, 1998-1999, 1999-2000 y 2000-2001. Paneles compuestos por 20 sueros (12 de estos positivos a anticuerpos IgM contra el dengue) fueron enviados a laboratorios de la Región para que participaran en los controles realizados. Los sueros de los paneles eran negativos a anticuerpos contra el virus de la inmunodeficiencia humana y el virus de la hepatitis C, así como al antígeno de superficie de la hepatitis B, y fueron almacenados a -20 °C hasta su envío en refrigeración a los laboratorios participantes. La presencia de anticuerpos IgM se determinó mediante un ensayo inmunoenzimático (ELISA) de captura, mientras que el título de anticuerpos IgG se determinó por inhibición de la hemoaglutinación o ELISA de IgG. Los resultados de la determinación de anticuerpos IgM contra el dengue que no coincidían con los del centro de referencia se consideraron discordantes. El título de anticuerpos IgG se consideró discordante cuando los resultados difirieron en dos diluciones o más con respecto al resultado del centro de referencia. RESULTADOS: Un total de 27 laboratorios recibió 59 paneles de sueros de 1996 a 2001, y se recibieron los resultados del análisis de 54 de esos paneles (91,5 por ciento). De 1 080 sueros (20 X 54), 95,6 por ciento coincidieron con el laboratorio de referencia en cuanto a los resultados de la detección de anticuerpos IgM contra el dengue. Además, en 47 paneles (87 por ciento) la coincidencia con el laboratorio de referencia se observó en 90 por ciento de las muestras del panel o más. De los 27 paneles para los cuales se recibieron los resultados de los títulos de anticuerpos IgG contra el dengue, 22 (81,5 por ciento) coincidieron con el centro de referencia. Tomando en conjunto los cuatro controles realizados, 22 laboratorios coincidieron con el centro de referencia en 90 por ciento de las muestras o más y 13 en 100 por ciento de las muestras en cuanto a la presencia de IgM. CONCLUSIONES: Los resultados indican que la mayoría de los laboratorios participantes mostraron un excelente desempeño en la detección de anticuerpos IgG e IgM contra el dengue. No obstante, las deficiencias encontradas ...

Objective. To report the results from participating laboratories for four external quality control proficiency tests of dengue serological diagnosis that were carried out in the Region of the Americas in the period of 1996­2001. Methods. External quality control proficiency tests of dengue serological diagnosis were carried out in 1996­1997, 1998­1999, 1999­2000, and 2000­2001. Panels made up of 20 serum samples (12 of them positive for dengue IgM antibodies) were sent to participating laboratories in the Region. The sera were negative for HIV antibodies, hepatitis C virus antibodies, and hepatitis B surface antigen. The sera were stored at ­20 °C until they were sent in refrigerated shipments to the participating laboratories. The presence of IgM antibodies was determined through IgM-capture enzyme-linked immunosorbent assay (ELISA), while the IgG antibody titer was determined by hemagglutination inhibition or by IgG ELISA. The results of the IgM antibody testing that differed from those of the reference center were considered discordant. The IgG antibody titer was considered discordant when the results differed by two dilutions or more with respect to the reference center's results. Results. A total of 27 laboratories received a total of 59 serum panels over the 1996­ 2001 period, and the results from testing 54 of those panels (91.5%) were sent back in. Of the total of 1 080 sera samples from those 54 panels, the results from 95.6% of the IgM antibody tests were concordant with the results from the reference center. With 47 of the 54 panels (87.0%) the participating laboratories' agreement with the reference center's results for the IgM antibody testing was 90.0% or higher. The laboratories sent back results from a total of 27 IgG antibody titer tests, and 22 of them (81.5%) coincided with those from the reference center. Considering the IgM antibody testing results from the four periods, the findings from 22 of the participating laboratories coincided with those from the reference center for at least 90% of the samples, and 13 of the laboratories were in complete concordance with the reference center. Conclusions. The majority of the participating laboratories showed an excellent level of performance in detecting dengue IgG and IgM antibodies. However, the deficiencies found in some instances confirm the need for continuing to improve laboratory diagnosis of dengue in the Region of the Americas

Isolation and identification of Adenovirus in hospitalized children, under five years, with acute respiratory disease, in Havana, Cuba

Nine Adenovirus (Ad) strains isolated in Cuba, from 128 nasopharingeal swab specimens of children below five years old, with acute respiratory diseases, during 1996 and 1997, were studied by restriction enzyme analysis of genomic DNA with two endonucleases BamH I and Sma I. All different fragment patterns were compared with the respective prototypes. The identified adenoviruses were Ad 1 (n=4), Ad 2 (n=1) and Ad 6 (n=4). Males were more frequently infected than females. The analysis of the occurrence of these Adenovirus strains of subgenus C revealed that Ad 1 and Ad 6 were the predominant serotypes in 1996 and in 1997, respectively