Epidemiology of human adenovirus infection in children hospitalized with lower respiratory tract infections in Hunan, China

To investigate the current genotypes of circulating human adenovirus (HAdV) strains, we molecularly genotyped HAdV in the nasopharyngeal aspirates (NPAs) of patients with acute lower respiratory tract infections (ALRTIs) and attempted to determine their associations with clinical symptoms. A total of 4751 NPA samples were collected from 4751 patients admitted to Hunan Provincial People's Hospital from September 2007 to March 2014, of which 447 (9.4%) samples were HAdV positive. Fourteen different HAdV types were identified; HAdV types 1 to 7 (HAdV 1-7) were identified in 95.7% of the 447 NPA samples with HAdV-7 and HAdV-3 being the most prevalent. In addition, 93.3% (417 of 447) of patients were younger than 5 years. The incidence of HAdV infection peaked in summer. Different HAdV types showed a predilection for different age groups and different seasonal distribution patterns. Coinfection of HAdVs and other respiratory viruses was detected in 63.3% (283 of 447) of the HAdV-positive samples. The most common clinical diagnosis was pneumonia and the most common symptoms were fever and cough. In comparison with children infected with HAdV-3 alone, those infected with HAdV-7 alone had an increased frequency of severe pneumonia involvement (11.6% vs 32.4%; P = 0.031), higher intensive care unit admission rates (7.0% vs 26.5%; P = 0.019), and a longer length of hospital stay (P = 0.03). Mixed infections in younger children were associated with a longer hospital stay (P = 0.023). Our results demonstrate the recent changes in the trends of circulating HAdV genotypes associated with ALRTIs in Hunan China.