Those in the relevant area that need to know, probably already do so. It sounds as though the yard is dealing with it in a professional and open manner, if you browse their facebook face you can read the details. Having dealt with an EHV 1 outbreak in the past, i wish them well getting through this difficult time.
Here here, just read the statement on my FB.
Wouldn't it be brilliant if everyone with an infectious illness on their yard could be so honest and open. I imagine he will get a lot of respect for this.