[Viral etiology of acute respiratory infections]. / Etiología viral de las infecciones respiratorias agudas.

Acute respiratory infections (ARI) are pathologies that affect the respiratory tract from the proximal pharynx to the lungs, with an evolution of less than 15 days. They constitute the most frequent cause of morbimortality in the world. With the purpose of identifying the viral agents associated to this type of infections in patients of Zulia State, Venezuela, between February 2005 and July 2006, a total of 102 samples of the respiratory tract (oropharyngeal swab, nasopharyngeal swab, nasopharyngeal washing, spit and bronchoalveolar lavage) were studied. Viral isolation was made through a cellular culture and the identification of the pathogenic agents by the technique of direct immunofluorescence. Forty six positive samples were obtained (45%). The greater incidence was found in the groups of 41 to 64 years old patients, followed by lactanting babies (1 to 23 months). There were no significant differences between sexes. Within the isolated viral pathogens, Respiratory Syncytial Virus (RSV) was the agent most frequently found (32.6% p < 0.05), followed by Adenovirus (28.2%), Parainfluenza (23.9%) and Influenza (15.2%). The respiratory infections of the low respiratory tract were the most frequent (67.4%). A high incidence of associated viral agents to ARI in Zulia State is demonstrated. A high incidence in adult patients and the greatest positivity was found for RSV.

Etiología viral de las infecciones respiratorias agudas / Viral etiology of acute respiratory infections

Las infecciones respiratorias agudas (IRA) son patologías que afectan el tracto respiratorio desde la faringe proximal hasta los pulmones, con una evolución de menos de 15 días y constituyen la causa más frecuente de morbimortalidad en el mundo. Con la finalidad de identificar los agentes virales asociados a este tipo de infecciones en pacientes del estado Zulia, Venezuela, entre febrero 2005 y julio de 2006, se estudiaron un total de 102 muestras provenientes del tracto respiratorio (hisopado nasal, faríngeo y/o nasofaríngeo, esputo y lavado broncoalveolar) de pacientes con clínica de IRA. El aislamiento viral se realizó a través del cultivo celular y la identificación del agente patógeno por la técnica de inmunofluorescencia directa. Se obtuvieron 46 muestras positivas (45%), la incidencia estuvo homogéneamente distribuida en todos los grupos de estudio aun cuando se observó predominio en el grupo de 41 a 64 años, seguido de los lactantes. No hubo diferencias significativas en cuanto al sexo. Dentro de los patógenos virales aislados el Virus Sincicial Respiratorio (VSR) fue el agente con mayor frecuencia (32,6%) (p<0,05), seguido de Adenovirus (28,2%), Parainfluenza (23,9%) e Influenza (15,2%). Las infecciones respiratorias del tracto inferior fueron las más frecuentes (67,4%). Se demuestra una alta incidencia de agentes virales asociados a IRA en el estado Zulia. Se destaca la alta frecuencia en pacientes adultos y la mayor positividad para VSR.

Acute respiratory infections (ARI) are pathologies that affect the respiratory tract from the proximal pharynx to the lungs, with an evolution of less than 15 days. They constitute the most frequent cause of morbimortality in the world. With the purpose of identifying the viral agents associated to this type of infections in patients of Zulia State, Venezuela, between February 2005 and July 2006, a total of 102 samples of the respiratory tract (oropharyngeal swab, nasopharyngeal swab, nasopharyngeal washing, spit and bronchoalveolar lavage) were studied. Viral isolation was made through a cellular culture and the identification of the pathogenic agents by the technique of direct immunofluorescence. Forty six positive samples were obtained (45%). The greater incidence was found in the groups of 41 to 64 years old patients, followed by lactanting babies (1 to 23 months). There were no significant differences between sexes. Within the isolated viral pathogens, Respiratory Syncytial Virus (RSV) was the agent most frequently found (32.6% p<0.05), followed by Adenovirus (28.2%), Parainfluenza (23.9%) and Influenza (15.2%). The respiratory infections of the low respiratory tract were the most frequent (67.4%). A high incidence of associated viral agents to ARI in Zulia State is demonstrated. A high incidence in adult patients and the greatest positivity was found for RSV.

In vitro, melatonin treatment decreases nitric oxide levels in murine splenocytes cultured with the venezuelan equine encephalomyelitis virus.

The purpose of this work was to determine the effect of melatonin on the nitric oxide levels in murine splenocytes cultured with the Venezuelan equine encephalomyelitis virus. After incubation, nitric oxide levels were measured by the diazotization assay. Those cultures with the Venezuelan equine encephalomyelitis virus increased nitric oxide levels. Splenocytes infected and treated with 100 and 150 microg/ml of melatonin, decreased significantly the nitric oxide levels when compared to infected and non-treated splenocytes. These findings show that splenocytes infected with the Venezuelan equine encephalomyelitis virus generate important amounts of nitric oxide and suggest that melatonin protects the mice infected with the Venezuelan equine encephalomyelitis virus by a mechanism involving the decreasing of nitric oxide concentrations in tissue.