What is the most common sign of B virus infection in macaques?

The most common sign of B virus infection in macaques is the presence of oral ulcers. This viral infection, caused by the monkey B virus (also known as Cercopithecine herpesvirus 1), primarily affects macaques and can lead to the development of painful lesions within the oral cavity. These ulcers can significantly impact the animal's ability to eat and drink, thus serving as a critical diagnostic indicator for veterinarians and researchers.

In the context of monitoring animal health, the identification of oral ulcers is particularly important because it can lead to the early detection of B virus infection, allowing for timely intervention. Other symptoms may accompany the infection, but oral ulcers are a hallmark sign that can point specifically to B virus, distinguishing it from other potential health issues in macaques.