Epidemiological investigation of equine rotavirus B outbreaks in horses in central Kentucky.

This research investigates the presence and stability of equine rotavirus group B (ERVB) in horse populations in central Kentucky. Through various analytical methods, the study found high prevalence of ERVB and its DNA in fecal, soil, water, and indoor samples collected during foal diarrhea outbreaks, highlighting the need for continued monitoring and countermeasures against this disease in horse populations and their environments.

Research Methodology

• The researchers based their study on metagenomic sequencing to identify equine rotavirus group B (ERVB) of ruminant origin in foal diarrhea outbreaks during the 2021 foaling season.
• In the 2022 foaling season, they collected mare and foal fecal samples from different farms in Central Kentucky to further investigate ERVB occurrence and determine its environmental stability.
• The occurrence of ERVB was detected using RT-qPCR-based analyses.

Results

• The study found ERVB genome in 16.67% of surveyed mare samples and 26.56% of foal samples.
• Out of 17 soil samples and 13 water samples collected from ERVB-positive farm premises, 94.12% and 100% tested weakly positive respectively.
• About 58.33% of indoor samples collected from the equipment, barn, and hospital wards during the outbreak period also confirmed ERVB presence.
• In the seroprevalence study, 87% of surveyed horse serum samples tested positive for ERVB antibodies.

Phylogenetic Analyses

• After unsuccessful attempts at ERVB cultivation, the researchers turned to phylogenetic analyses.
• The strains found in the 2022 and 2023 outbreaks were closely related to ruminant rotavirus B, similar to strains from 2021.
• Further sequence analyses showed no notable mutations in the three viral capsid proteins over the past three years. These proteins are the primary targets of virus-neutralizing antibodies.

Conclusion and Recommendations

• The study demonstrated widespread and stable presence of ERVB in horses on affected farms.
• Given these results, the researchers recommend continued surveillance of ERVB in horses and their environments.
• They also advocate for the development of effective countermeasures to protect horses against this newly identified viral disease.