Human parainfluenza viruses (HPIVs) are an important cause of acute lower respiratory tract infections (ALRTIs). HPIV‐4, a newly identified virus, has been associated with severe ALRTIs recently. A total of 771 nasopharyngeal aspirate samples were collected from hospitalized children between March 2010 and February 2011. HPIVs were detected by Nest‐PCR, and other known respiratory viruses were detected by RT‐PCR and PCR. All amplification products were sequenced. HPIVs were detected in 151 (19.58%) patients, of whom 28 (3.63%) were positive for HPIV‐4, 12(1.55%) for HPIV‐1, 4 (0.51%) for HPIV‐2, and 107 (13.87%) for HPIV‐3. Only three were found to be co‐infected with different types of HPIVs. All HPIV‐positive children were under 5 years of age, with the majority being less than 1 year. Only the detection rate of HPIV‐3 had a significant statistical difference (χ² = 29.648, P = 0.000) between ages. HPIV‐3 and HPIV‐4 were detected during the summer. Sixty (39.74%) were co‐infected with other respiratory viruses, and human rhinovirus (HRV) was the most common co‐infecting virus. The most frequent clinical diagnosis was bronchopneumonia, and all patients had cough; some patients who were infected with HPIV‐3 and HPIV‐4 had polypnea and cyanosis. No significant difference was found in clinical manifestations between those who were infected with HPIV‐4 and HPIV‐3. Two genotypes for HPIV‐4 were prevalent, although HPIV‐4a dominated. HPIV‐4 is an important virus for children hospitalized with ALRTIs in China. HRV was the most common co‐infecting virus. Two genotypes for HPIV‐4 are prevalent, HPIV‐4a dominated. J. Med. Virol. 88:2085–2091, 2016.

To explore the epidemiological and clinical features of different human metapneumovirus (hMPV) genotypes in hospitalized children. Reverse transcription polymerase chain reaction (RT‐PCR) or PCR was employed to screen for both hMPV and other common respiratory viruses in 2613 nasopharyngeal aspirate specimens collected from children with lower respiratory tract infections from September 2007 to February 2011 (a period of 3.5 years). The demographics and clinical presentations of patients infected with different genotypes of hMPV were compared. A total of 135 samples were positive for hMPV (positive detection rate: 5.2%). Co‐infection with other viruses was observed in 45.9% (62/135) of cases, and human bocavirus was the most common additional respiratory virus. The most common symptoms included cough, fever, and wheezing. The M gene was sequenced for 135 isolates; of these, genotype A was identified in 72.6% (98/135) of patients, and genotype B was identified in 27.4% (37/135) of patients. The predominant genotype of hMPV changed over the 3.5‐year study period from genotype A2b to A2b or B1 and then to predominantly B1. Most of clinical features were similar between patients infected with different hMPV genotypes. These results suggested that hMPV is an important viral pathogen in pediatric patients with acute lower respiratory tract infection in Changsha. The hMPV subtypes A2b and B1 were found to co‐circulate. The different hMPV genotypes exhibit similar clinical characteristics. J. Med. Virol. 87:1839–1845, 2015.

Purpose: To evaluate viral loads in children with human adenovirus (HAdV) pneumonia at different stages of disease and compare the viral load between upper and lower respiratory tract samples. Methods: We prospectively enrolled children who required invasive ventilation for HAdV pneumonia. Nasopharyngeal aspirate (NPA) and tracheal aspirate (TA) samples were collected throughout the entire period of invasive ventilation. Viral detection and quantification were performed using quantitative real-time polymerase chain reaction. Results: Ninety-four children were enrolled. The median age of the children was 12.0 months (IQR: 11.0–24.0), and > ninety percent of patients were aged between 6 and 59 months. Seven hundred and nine paired NPA-TA samples were collected. The median viral loads of the NPA and TA samples were 7.31 log10 and 7.50 log10 copies/mL, respectively. Viral loads generally decreased steadily over time. The median viral load after 1, 2, 3, and > 3 weeks of the disease course was 8.65, 7.70, 6.69, and 5.09 log10 copies/mL, respectively, in NPA samples and 8.67, 7.79, 7.08, and 5.53 log10 copies/mL, respectively, in TA samples. Viral load showed a significant negative correlation with time since symptom onset in both NPA samples (Spearman r = − 0.607, P = 0.000) and TA samples (Spearman r = − 0.544, P = 0.000). The predicted duration of HAdV shedding was 60.17 days in the NPA group and 65.81 days in the TA group. Viral loads in NPA and TA from the same subjects correlated well with each other (R² = 0.694). HAdV loads in NPA and TA were most comparable during the early phase of infection (95% limits of agreement, − 1.36 to 1.30 log10 copies/mL, R² = 0.746). Variation increased during the late phase of infection (i.e., in follow-up samples), with viral loads remaining significantly higher in TA than NPA. Conclusions: In children with HAdV pneumonia, viral loads in both NPA and TA steadily decreased during the course of the disease, and the predicted duration of viral shedding was more than 2 months. The HAdV DNA load of NPA is highly correlated with that of TA, especially in the initial phase of infection.