[Clinical and epidemiological characteristics of respiratory infections caused by human metapneumovirus in pediatric patients]. / Características clínicas y epidemiológicas de las infecciones respiratorias causadas por el metapneumovirus humano en pacientes pediátricos.

INTRODUCTION: Human Metapneumovirus (hMPV) was first identified in 2001 in respiratory samples from children and adults with acute respiratory tract infection. The aim of this prospective study was to determine the clinical and epidemiological characteristics of pediatric patients with an acute respiratory tract infection and exclusive isolation of hMPV in respiratory samples (December 2005-January 2007). MATERIAL AND METHODS: All respiratory tract samples were submitted to rapid antigen detection against respiratory syncytial virus (RSV) and influenza A and B viruses. To isolate respiratory viruses, samples were inoculated in various cell lines using the shell vial culture assay. To isolate hMPV, the LLC-MK2 cell line was used. Only antigen-negative samples were studied for the presence of hMPV. RESULTS: Over the study period, 32 hMPV were isolated from different patients, accounting for 1.7% of all samples studied for this virus (only RSV-negative samples, 1,791) and 1.5% of all samples studied. Peak incidence was found between December and March of the two years studied. Of the 32 patients in whom hMPV was detected, 17 (53.2%) were female and 15 (46.8%) male. Mean age was 12.5 months (range, 1 month-4 years). The most frequent clinical symptoms were fever (90.6%), cough (87.5%), rhinorrhea and bronchiolitis (46.8%). Three patients (9.4%) were hospitalized. CONCLUSIONS: Respiratory infection caused by hMPV is considered an emergent disease in pediatric patients. The clinical manifestations are very similar to those of RSV infection; hence, only virological study can establish the definite etiological diagnosis.

Características clínicas y epidemiológicas de las infecciones respiratorias causadas por el metapneumovirus humano en pacientes pediátricos / Clinical and epidemiological characteristics of respiratory infections caused by human Metapneumovirus in pediatric patients

Introducción. El metapneumovirus humano (MPVh) fue identificado por primera vez en 2001 a partir de aspirados nasofaríngeos de niños y adultos con infección aguda del tracto respiratorio. El objetivo de este estudio prospectivo es conocer las características clínicas y epidemiológicas de los pacientes pediátricos con infección respiratoria aguda y aislamiento exclusivo del MPVh (diciembre 2005-enero 2007). Material y métodos. Las muestras fueron sometidas a la detección antigénica rápida frente al virus respiratorio sincitial (VRS) y los virus gripales A y B. Las muestras fueron sembradas en shell-viales de diferentes líneas celulares para el aislamiento de virus respiratorios. Para el MPVh se utilizó la línea LLC-MK2. Sólo las muestras negativas en las técnicas antigénicas fueron estudiadas para la presencia del MPVh. Resultados. En este estudio se han aislado 32 MPVh de pacientes distintos, que representan el 1,7% de todas las muestras estudiadas para este virus (sólo las negativas al VRS: 1.791) y el 1,5% de todas las muestras analizadas. La mayoría de casos se presentaron entre los meses de diciembre y marzo de ambos años estudiados. Los 32 casos correspondían a 17 niñas (53,2%) y 15 niños (46,8%). La edad media de los pacientes fue de 12,5 meses (intervalo: 1 mes y 4 años). La mayoría de los pacientes presentaron fiebre (90,6%), tos (87,5%), rinorrea y bronquiolitis (46,8%). Sólo 3 pacientes (9,4%) precisaron de ingreso hospitalario. Conclusiones. Las infecciones respiratorias causadas por el MPVh se han convertido en una enfermedad emergente en la población pediátrica. Las manifestaciones clínicas no permiten realizar un diagnóstico diferencial con el VRS, de modo que sólo el estudio virológico permitirá establecer el diagnóstico etiológico definitivo (AU)

Introduction. Human Metapneumovirus (hMPV) was first identified in 2001 in respiratory samples from children and adults with acute respiratory tract infection. The aim of this prospective study was to determine the clinical and epidemiological characteristics of pediatric patients with an acute respiratory tract infection and exclusive isolation of hMPV in respiratory samples (December 2005-January 2007). Material and methods. All respiratory tract samples were submitted to rapid antigen detection against respiratory syncytial virus (RSV) and influenza A and B viruses. To isolate respiratory viruses, samples were inoculated in various cell lines using the shell vial culture assay. To isolate hMPV, the LLC-MK2 cell line was used. Only antigen-negative samples were studied for the presence of hMPV. Results. Over the study period, 32 hMPV were isolated from different patients, accounting for 1.7% of all samples studied for this virus (only RSV-negative samples, 1,791) and 1.5% of all samples studied. Peak incidence was found between December and March of the two years studied. Of the 32 patients in whom hMPV was detected, 17 (53.2%) were female and 15 (46.8%) male. Mean age was 12.5 months (range, 1 month-4 years). The most frequent clinical symptoms were fever (90.6%), cough (87.5%), rhinorrhea and bronchiolitis (46.8%). Three patients (9.4%) were hospitalized. Conclusions. Respiratory infection caused by hMPV is considered an emergent disease in pediatric patients. The clinical manifestations are very similar to those of RSV infection; hence, only virological study can establish the definite etiological diagnosis (AU)

Comparison of different cell lines and incubation times in the isolation by the shell vial culture of human metapneumovirus from pediatric respiratory samples.

We report a prospective study concerning the efficacy of LLC-MK2 (continuous monkey kidney cell), Hep-2, MDCK (Madin-Darby Canine Kidney), Vero and MRC-5 cell lines, by shell vial assay, and incubation time in the isolation of hMPV from pediatric respiratory samples. The overall sensitivity of the cell lines studied were: 100% for the LLC-MK2, 68.7% for the Hep-2, 28.1% for the Vero, 3.1% for the MDCK and 0% for the MRC-5. Only one strain (3.1%) showed growth in the four cell lines studied and 10 (31.2%) strains only grew in the LLC-MK2 cell line. The analysis of incubation times showed that only 14 strains (43.7%) were able to grow after 3 days of incubation, while all strains (100%) showed growth after 5 days. The use of shell vials with commercial LLC-MK2 cells could be a method for isolating hMPV from respiratory samples in the pediatric population.