Identification of a Ruminant Origin Group B Rotavirus Associated with Diarrhea Outbreaks in Foals.

Area of Science:

• Veterinary Virology
• Equine Infectious Diseases
• Molecular Epidemiology

Background:

• Equine rotavirus group A (ERVA) is a common cause of foal diarrhea.
• An unusual increase in severe neonatal foal diarrhea cases occurred in Central Kentucky in early 2021.
• Standard diagnostic tests failed to identify known enteric pathogens, including ERVA.

Purpose of the Study:

• To identify the causative agent of severe diarrhea outbreaks in neonatal foals in Kentucky.
• To characterize the novel rotavirus strain detected in affected foals.
• To investigate the potential origin and prevalence of this new equine rotavirus strain.

Main Methods:

• Metagenomic sequencing of fecal samples from affected foals.
• Phylogenetic analysis of viral genetic material.
• Reverse transcription quantitative polymerase chain reaction (RT-qPCR) for targeted detection.

Main Results:

• A novel equine rotavirus group B (ERVB) was identified as the sole pathogen in affected foals.
• ERVB shared high protein sequence identity (>96%) with ruminant rotavirus group B strains.
• Phylogenetic analysis linked ERVB to caprine and bovine strains from the USA.
• RT-qPCR confirmed ERVB in 69.69% of sampled diarrheic foals.

Conclusions:

• The findings suggest ERVB, likely originating from ruminants, caused the 2021 neonatal foal diarrhea outbreak in Kentucky.
• This emergence of a ruminant-like rotavirus in foals highlights a significant cross-species transmission event.
• Further investigation is warranted due to the disease's impact on foal health and the equine industry's economy.