Objective: To probe into the epidemiology and clinical characteristics of human parainfluenza virus 3 pneumonia in children in Suzhou and its correlation with climatic factors. Methods: Nasopharyngeal secretions of 7

525 hospitalized children with community-acquired pneumonia (CAP) admitted into Children’s Hospital Affiliated to Soochow University from 2014 to 2017 were collected. Human parainfluenza virus 1

2

3 (HPIV1

HPIV2

HPIV3)

respiratory syncytial virus (RSV)

adenovirus (ADV) and influenza virus A

B (InfA

InfB) were detected by direct immunofluorescence. Human metapneumovirus and human rhinovirus (HRV) were detected by reverse transcription polymerase chain reaction (RT-PCR). Human bocavirus (HBoV) was detected by real-time fluorescent PCR. The correlation between climatic factors and the prevalence of HPIV3 pneumonia was analyzed. Results: Of the 7

525 cases

268 cases (3.56%) were positive for HPIV3

and the top 3 viruses detected were respectively HRV

RSV and HPIV3. The main clinical manifestations of HPIV3 pneumonia were cough (98.13%)

wheezing (38.06%) and fever (46.64%). HPIV3 pneumonia was likely to occur at 6 to 12 months of age

and was more frequent in spring and summer; RSV pneumonia was likely to occur at 0 to 6 months of age

and was more frequent in autumn and winter. High fever was more common in HPIV3 pneumonia

while wheezing

shortness of breath and severe illness were more common in RSV pneumonia. The detection rate of HPIV3 was highly positively correlated with monthly average temperature and total monthly rainfall (P<0.01)

and was moderately positively correlated with monthly average wind speed (P<0.05). Conclusion: HPIV3 is the third viral pathogen of CAP hospitalized children in Suzhou. The detection rate of HPIV3 is the highest at 6 to 12 months of age

and the epidemic peak is in spring and summer. The detection rate of HPIV3 is highly positively correlated with monthly average temperature and total rainfall

and is moderately positively correlated with monthly average wind speed.