Epidemiology of equine rotavirus infection among foals in the breeding region.

The research study focuses on investigating the prevalence of rotavirus infections in foals in the Hidaka region of Hokkaido, Japan. Specifically, it analyses the relationship between the age of foals and instances of rotavirus infection, noting that such infections are particularly common amongst foals aged 1 to 3 months.

Context and Focus of the Study

• The researchers aim to provide a detailed report on the occurrence of diarrhea in foals caused by rotavirus, a known cause of acute diarrhea in infant mammals.
• A practical context for this research is provided by the significant population of light breed horses in the Hidaka region of Hokkaido, where more than 90% of these horses in Japan are produced.
• This study draws upon serological surveys indicating extensive spread of rotavirus among horses and foals, both in Japan and the U.S.A.

Study Methodology

• The researchers isolated the rotavirus from fecal samples of foals with diarrhea from 1983 to 1989, using a process involving MA-104 cells and trypsin.
• The isolated viruses were then identified using indirect immunofluorescent technique with the application of anti-calf rotavirus (NCDV) guinea-pig serum.
• The relationship between rotavirus infection and age was determined by examining the number and age of foals diagnosed with rotavirus infection during the same time frame.

Key Findings of the Study

• The data shows that instances of foal diarrhea, likely caused by rotavirus, were most prevalent from March to August, with peak cases occurring from April to July.
• Rotavirus was isolated from 28.1% of fecal samples, with this rate varying between 15.5% and 50.0% throughout the seven-year period. Notably, the average isolation rates were highest in May, June, and July.
• The analysis clarifies that rotavirus is a significant cause of diarrhea in foals, and the infection rate is highest amongst foals aged 1 to 3 months.

Interpretation and Implications

• The study’s findings show that foals aged 1-3 months are particularly susceptible to rotavirus, presumed to be due to the disappearance of passive immunity during this time.
• The research suggests that the frequent occurrence of rotavirus infection from May to July may be due to an increased number of foals aged 1-3 months during this period.
• The results imply the need for further investigations into the electrophoreotypes and serotypes of rotavirus prevalent among foals in the Hidaka region as these could assist in dealing and managing such viral outbreaks better in the future.