Viral pathogens of acute lower respiratory infections in pre-school Nigerian children and clinical implications of multiple microbial identifications.

In a prospective study of acute lower respiratory infections (ALRI), at the University College Hospital, UCH, Ibadan, 35 viral pathogens were identified by immunofluorescence (IF) techniques from 24 (68.6%) respiratory specimens from 35 hospitalised pre-school children. The respiratory diagnoses comprised croup, bronchiolitis, pneumonia and pleural effusion. The viral identifications comprised 14 (40.0%) of parainfluenza virus type 3, 10 (28.6%) of respiratory syncytial virus (RSV), 5 (14.3%) of influenza virus type A, 4 (11.4%) of parainfluenza virus type 1 and 2 (5.7%) of influenza virus type B. Two or more viral agents were identified in as many as 10 (41.7%) of the 24 IF positive secretions, 8 (80.0%) of which were obtained from children with features of protein energy malnutrition. Twenty subjects had both virological and bacteriological analyses, in 8 (40.0%) of whom co-existing bacteraemia was identified. Four (50.0%) of these blood culture positive subjects, also had features of overt malnutrition. Neither the age nor the sex was significantly related to the viral identifications (P > 0.81 & 0.35 respectively). Similarly, the final respiratory diagnoses were not significantly related to the viral identifications despite the seemingly suggestive relationship between a diagnosis of croup and parainfluenza identifications as well as that between pneumonia and RSV/parainfluenza type 3 identifications. It is concluded that the high proportion of positive viral identifications is a pointer to the importance of viruses as possible primary etiological agents of ALRI in countries of the West African sub-region and perhaps in developing countries of other tropical subregions. The multiplicity of microbial identifications (viruses and bacteria), seen in malnourished children, may explain the clinical severity of ALRI in the same group of children. The usefulness of IF as a rapid diagnostic tool, as well as the potential implications of our findings on ARI control in developing countries, are discussed.