Outbreak of equine coronavirus infection among riding horses in Tokyo, Japan

• Published in: Comparative immunology, microbiology and infectious diseases Vol. 77; p. 101668
• Main Authors: Kambayashi, Yoshinori, Bannai, Hiroshi, Tsujimura, Koji, Hirama, Akiko, Ohta, Minoru, Nemoto, Manabu
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.08.2021; Elsevier Science Ltd
• Subjects: Anorexia; Coronaviruses; Diarrhea; Equine coronavirus; Fever; Genomes; Horses; Infections; Japan; Lethargy; Neutralization; Nucleotide sequence; Outbreak; Outbreaks; Polymerase chain reaction; Sequence analysis; Shedding; Spreaders; Subclinical infection; Thoroughbred; Viruses; Japan; Equine coronavirus; Subclinical infection; Outbreak; Japan; Thoroughbred
• ISSN: 0147-9571; 1878-1667
• DOI: 10.1016/j.cimid.2021.101668

•An outbreak of equine coronavirus (ECoV) infection occurred among 41 horses.•All 41 horses were infected with ECoV but only 15 of them showed clinical signs.•No affected horses showed severe signs, and all recovered within 3 days.•Subclinical horses likely played an important role as spreaders.•Non-Thoroughbred horses shed ECoV in faeces longer than Thoroughbreds. In 2020, an outbreak of equine coronavirus (ECoV) infection occurred among 41 horses at a riding stable in Tokyo, Japan. This stable had 16 Thoroughbreds and 25 horses of other breeds, including Andalusians, ponies and miniature horses. Fifteen horses (37 %) showed mild clinical signs such as fever, lethargy, anorexia and diarrhoea, and they recovered within 3 days of onset. A virus neutralization test showed that all 41 horses were infected with ECoV, signifying that 26 horses (63 %) were subclinical. The results suggest that subclinical horses played an important role as spreaders. A genome sequence analysis revealed that the lengths from genes p4.7 to p12.7 or NS2 in ECoV differed from those of ECoVs detected previously, suggesting that this outbreak was caused by a virus different from those that caused previous outbreaks among draughthorses in Japan. Among 30 horses that tested positive by real-time RT-PCR, ECoV shedding periods of non-Thoroughbreds were significantly longer than those of Thoroughbreds. The difference in shedding periods may indicate that some breeds excrete ECoV longer than other breeds and can contribute to the spread of ECoV.