DALLAS — In Washington, a patient who had traveled to Nigeria and who was suspected of having Ebola was placed in isolation at Howard University Hospital on Thursday. In New Haven, two Yale University graduate students plan to sequester themselves when they return this weekend from Liberia, where they have helped the government develop a system to track the Ebola epidemic. And at Newark Liberty International Airport on Saturday, a sick man who had just arrived from Brussels was rushed to a hospital amid concerns that he was showing Ebola-like symptoms, a fear later dismissed by hospital officials. With fears...