Prevalence of Parainfluenza Viruses in Seoul, 2021 - 2022.

BACKGROUND: Parainfluenza virus (PIV) is a significant etiological agent of acute lower respiratory tract infections (ALRIs) in infants and young children. The present study has been conducted to investigate the prevalence of recently identified respiratory viruses. METHODS: In total, 543 oropharyngeal or nasopharyngeal swab samples collected from hospitalized patients with acute respiratory symptoms (ARS) between January and December 2021 (5,653 females and 4,950 males) were tested for respiratory viruses using RT-PCR. RESULTS: At least one respiratory virus was detected by RT-PCR in 119 out of 175 samples (68%). The most frequently detected virus was human rhinovirus (HRV) (34, 6.5%), followed by human parainfluenza viruses (HPIVs) (19, 3.6%), human bocavirus (HBoV) (8, 1.5%), human adenovirus (HAdV) (7, 1.3%), and human respiratory syncytial virus (HRSV) (4, 0.8%). HPIV-3 accounted for 3.6% (19/175) of all viral pathogens and was the second most frequently detected viral pathogen in our study. HPIV-3 infections peaked in the fall (November) of 2021. Phylogenetic analysis of the coding region of the viral protein HA revealed that all 35 (100%) of 35 HPIV-infected patients were infected with HPIV-3. CONCLUSIONS: HPIV was an important causative pathogen associated with ALRI in children hospitalized in Korea in the late fall of 2021, as the social distancing rules for COVID-19 were relaxed. These findings highlight the im-portance of HPIV as a cause of ALRI.

Quantitative differential analysis of norovirus outbreak samples using RT-ddPCR.

Noroviruses cause acute gastroenteritis with symptoms of diarrhoea and vomiting, and their high infectivity allows outbreaks to readily occur. Quickly identifying and isolating potential contaminants is an effective method to prevent the spread of outbreaks. A total of 376 samples collected from nine outbreaks were categorized as either patient, asymptomatic individual, cook or environmental samples, according to the source of contamination. Using real-time PCR and sequencing analysis, norovirus GII genotypes were detected in 34·9% of samples from patients, 19·2% from asymptomatic individuals, 2·4% from the environment and 1·4% from cooks. Our findings showed contrasting results in samples categories quantified based on the limit of blank and detection limit by reverse transcription droplet digital PCR, which is a more sensitive testing method than real-time-PCR.