NEW YORK (AP) — U.S. health officials Tuesday laid out worst-case and best-case scenarios for the Ebola epidemic in West Africa, warning that the number of infected people could explode to at least 1.4 million by mid-January — or peak well below that, if efforts to control the outbreak are ramped up.

The widely varying projections by the Centers for Disease Control and Prevention were based on conditions in late August and do not take into account a recent international surge in medical aid for the stricken region. That burst has given health authorities reason for some optimism.