Epidemiological surveillance of avian coronavirus in China in 2024

To expand our understanding of the epidemiology of avian coronavirus (ACoV) in China, the risk-based active surveillance was carried out in China in 2024. A total of 7,699 avian swab samples were collected from 153 sampling sites in 13 provinces. One thousand fifty hundred and eighty-six ACoVs were detected and identified by RT-PCR and sequencing with a positive rate of 20.60 %, including 1,125 strains of avian infectious bronchitis virus (IBV), 278 strains of duck coronavirus (DuCoV), 182 strains of pigeon coronavirus (PiCoV), and 1 strain of deltacoronavirus. Most ACoVs were detected from chickens, followed by pigeons, while others were collected from ducks and geese. The positivity rates for ACoV in poultry ranged from 2.91 % to 32.27 %. The viruses were detected from 86 sampling sites (56.21 %) in all 13 provinces surveyed. The positivity rates of ACoV in retail markets (98.08 %) and wholesale markets (100 %) were much higher than those in slaughterhouses (80.00 %) and poultry farms (20.25 %). 231 representative IBV strains from different regions were selected for S1 gene sequencing and genetic evolution analysis. The results revealed that the prevalent IBV in China comprised ten genotypes, meanwhile the recombinant variants were also detected. The viruses in GI-19 (35.06 %) and GVI-1 (33.77 %) were the predominant strains in China. Importantly, no cases of SARS-CoV-2 were found in the detected poultry samples. This study reveals the prevalence, distribution, genetic and phylogenetic characteristics of ACoV in China, and extends our understanding of the epidemiological context of ACoV in China.