Occurrence of different viruses in acute respiratory tract infections of Nigerian children was examined. Respiratory swabs were collected from 246 children referred to hospital clinics because of acute respiratory symptoms from February through May 2009. Validated real-time RT-PCR techniques revealed nucleic acids of at least one virus group in 189 specimens (77%). Human rhinoviruses and parainfluenza viruses were present each in one third of the children. Adenoviruses, enteroviruses, human metapneumovirus, human bocavirus, and influenza C virus were also relatively common. Possibly due to their seasonal occurrence, influenza A and B virus, and respiratory syncytial virus were detected rarely. We conclude that all major groups of respiratory tract viruses are causing illness in Nigerian children. 1. Introduction Wide range of viruses is known to be associated with respiratory disease in humans. Adenoviruses, coronaviruses, human enteroviruses (HEV), human rhinoviruses (HRV), influenza viruses, parainfluenza viruses (PIV), and respiratory syncytial viruses (RSV) are well-known causes of acute respiratory tract infections (ARTI) in both industrialized and developing countries. Over the last decade, modern molecular techniques have led to the discovery of several previously unknown respiratory tract viruses, including human metapneumovirus (hMPV) [1], two new human coronavirus types [2, 3], human bocavirus (HBoV) [4], and two new human polyomaviruses [5, 6]. The significance of these novel viruses has been reviewed recently [7, 8]. It is widely accepted that common cold is almost always caused by viruses, most frequently by HRV [9], and viral infections are considered to contribute to the generation of complications of common cold, such as acute otitis media and sinusitis. Moreover, different viruses, including influenza viruses and RSV, are also frequently detected in samples obtained from patients with lower respiratory tract infection (LRTI), either alone or together with pathogenic bacteria. Several recent reports, including some from Africa, suggest viruses as potential etiologic agents in pneumonia in children [10–13], or exacerbations of asthma [14–16]. Several studies underscore the importance of respiratory tract viruses in Nigerian patients, but these studies were carried out before the introduction of modern molecular diagnostic techniques [14, 17–19]. The present study was designed to identify viral agents associated with respiratory infections among young children in Nigeria using modern, validated molecular techniques. We wanted to explore
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