Epidemical features of HAdV-3 and HAdV-7 in pediatric pneumonia in Chongqing, China.

Human adenoviruses (HAdV) of species B, C, and E (HAdV-B, -C, -E) are frequent causative agents of acute respiratory infections worldwide. No specific analysis has been done on the epidemiological and clinical features of HAdV in pediatric pneumonia in China. Nasopharyngeal aspirates were collected from hospitalized children with pneumonia from June 2009 to May 2014. All samples that tested positive for HAdV were typed by sequencing the hexon and fiber genes. From a total of 3089 samples, 208 (6.7 %) were positive for HAdV, identified as belonging to HAdV-B (186, 89.4 %), HAdV-C (9, 4.3 %) and HAdV-E (1, 0.5 %). HAdV-7 (104, 50.0 %) and HAdV-3 (78, 37.5 %) were the two major types, followed by HAdV-1, HAdV-55 and HAdV-14. There were 87 (41.8 %) single HAdV infections, of which 80 % were HAdV-7 infections. Multivariate analysis showed that single infections with HAdV-7 were associated with a higher prevalence of severe pneumonia. Temporal patterns showed that, except for a simultaneous outbreak of HAdV-3 and HAdV-7 during the years 2010-2011, HAdV-7 and HAdV-3 were alternately predominant, and the dominance shifted to HAdV-3 after 2014. Identification of the predominant HAdV genotypes and their epidemical features is useful for determining preventive strategies. HAdV-7 associated severe pneumonia needs to be considered with high priority in clinical practice.