[Analysis of enterovirus infection type among acute respiratory tract infection cases in Luohe City, Henan Province from 2017 to 2021]

Objective: To understand the infection status of Enterovirus (EV) in cases of acute respiratory infections (ARIs) in Luohe City, Henan Province from 2017 to 2021, and analyze the prevalence and type composition of EV in ARIs. Methods: From October 2017 to May 2021, pharyngeal swab samples were collected from 1 828 patients with ARIs in Luohe Central Hospital and the clinical epidemiological data of these cases were also collected. EV-positive samples were identified by Quantitative Real-time Polymerase Chain Reaction (qPCR). The 5'-untranslated region (5'UTR) was amplified by Reverse Transcription-Polymerase Chain Reaction (RT-PCR). The results of 5'UTR region were initially typed by Enterovirus Genotyping Tool Version 1.0. Based on the typing results, the full-length of VP1 region was amplified by RT-PCR. The EV typing was identified again by VP1 region. Results: Among 1 828 cases of ARIs, 56.7% (1 036) were males. The median (Q₁, Q₃) age was about 3 (1, 5) years. Patients under 5 years old accounted for 71.6% (1 309 cases). Among all cases, a total of 71 EV-positive samples were identified by qPCR, with a detection rate of 3.88% (71/1 828). The EV detection rates for men and women were 3.28% (34/1 036) and 4.67% (37/792), without statistically significant differences (χ²=2.32, P=0.14). The EV detection rates for 2 to <6 years, 6 months to <2 years, 6 to <10 years, and <6 months were 6.29% (48/763), 3.00% (18/600), 2.52% (4/159), and 1.67% (1/60) (χ²=27.91, P<0.001). The EV detection rate was 0.92% (3/326) in autumn and winter of 2017. The EV detection rates were 1.18% (6/508), 2.47% (12/485) and 8.31% (34/409) in each year from 2018 to 2020, with an increasing trend year by year(χ²_trend=29.76, P<0.001). The main prevalent seasons were summer and autumn. The detection rate in spring of 2021 was 4.00% (4/100). A total of 12 types were identified and classified as CVA2, CVA4, CVA5, CVA6, CVA10, CVB3, CVB5, E5, E11, E30, PV-1, and EV-D68. The types of CVA2, CVA10, CVA6, and CVB3 were the dominant phenotypes. In 59 sample of EV typing, the main clinical manifestation was upper respiratory tract infection (36/59, 61.01%). The dominant types detected in upper respiratory tract infections were CVA10 (10/36, 27.78%), CVA6 (9/36, 25.00%) and CVB3 (8/36, 22.22%). The dominant type detected in lower respiratory tract infections was CVA2 (7/19, 36.84%). Conclusion: In Luohe City, Henan Province from 2017 to 2021, EV infection in ARIs cases has clear seasonal and age-specific patterns, and the dominant types of upper and lower respiratory tract infections are different.