Fox News Ebola crisis: Yes, we need to help but is Obama ready to keep Americans safe? As the disease increases exponentially, the likelihood also increases that a person carrying Ebola, perhaps unknowingly, travels to the United States before symptom’s appear. Northeastern University professor Allesandra Vespignanini and his research team have developed a computerized risk assessment based on travel patterns, and pegs the risk at no more than 15 percent.