Hello clauee, is that the current working diagnosis on your horse? It should be noted that the range of infection severity is great varying from asymptomatic to in the rare case death. Death is usually associated with hyperammonemia-associated encephalopathy.
The disease is relatively new (10 years recognition) an currently there are no studies I have found on how long the stools remain infective. The stools should be considered infective at all times, removed, and the area sanitized. Looking at natural and experimental infections there are no reports that I can find that suggest a horse entered an area previously inhabited by a infected horse but is now empty of infected horses that has become ill but I continue to look. In one study the following history was available, note the one horse that did not seem to have a infection source:
One horse was associated with a barn with five additional confirmed ECoV cases, two study horses were from the same barn and hospitalised within the same week, and three separate study horses were associated with horses with fevers at their respective farms. Five of 22 horses (23%) for which travel history was available had traveled to a horse show within the previous 3 weeks.
Currently infection is considered likely when there is direct contact between infected stools and the mouth of an infected horse. Note that there have been identified inapparent shedders that can infect those without resistance.
DrO