DAKAR, Senegal (AP) — The fastest-growing Ebola outbreak in history has killed more than 1,000 people in eastern Congo as health officials race to contain a virus with no approved vaccine or treatment. Advertisement AdvertisementResponders are struggling to understand how far the Ebola outbreak has spread and how much worse it might become. U.S. Centers for Disease Control and Prevention researchers last month used computer modeling and found that in a worst-case scenario, the current Ebola outbreak could approach the worst in history. The CDC echoed that assessment in its latest situation report, saying Ebola doesn't spread like respiratory viruses such as flu or COVID-19. The outbreak has spread little beyond CongoThe vast majority of Ebola cases are concentrated in Congo.