Human parainfluenza virus infection in severe acute respiratory infection cases in Beijing, 2014-2016: A molecular epidemiological study

Background: Severe acute respiratory infection (SARI) threatens human health and even survival, causing a huge number of hospitalized patients every year. However, as one of the most common respiratory viruses circulated worldwide, the epidemiological and phylogenetic characteristics of human parainfluenza virus (HPIV) in these cases were not well known. Objectives: To reveal the epidemiological features of HPIV infection in SARIs in Beijing area from September 2014 to August 2016. Methods: A total of 1229 SARI cases in Beijing area were enrolled, investigated, sampled, and tested by multiplex real-time PCR to identify HPIVs and other common respiratory viruses. Eighteen HPIV-3 viruses isolated from all HPIV-positive samples in these SARI cases were sequenced and analyzed. Results: Among all enrolled cases, 0.81%, 0.73%, 4.48%, and 0.57% were positive for HPIV-1 to HPIV-4, respectively. The highest yield rate of HPIV infection occurred in children under 5 years old (9.07%), followed by the patients over 60 years old (6.02%). The phylogenetic information of HPIV-3 showed that all viruses belonged to Cluster C3a. Conclusions: Besides the young children, the elders older than 60 years also showed a relatively high infection rate of HPIVs, which should be given comparable attentions. Moreover, the HPIV-3 circulating in China undergoes continued evolution, suggesting the potential risk of evolved HPIV infection should not be overlooked.