BEIRA, Mozambique (AP) — A week after Cyclone Idai lashed southern Africa, flooding still raged as torrential rains caused a dam to overflow in Zimbabwe, threatening riverside populations. The confirmed death toll in Zimbabwe, neighboring Mozambique and Malawi surpassed 500 on Thursday, with hundreds more feared dead in towns and villages that were completely submerged.

Aid agencies and several governments continued to step up their deployments, with helicopters in short supply for hundreds of thousands of people displaced by the cyclone.

Spokesman Herve Verhoosel of the World Food Program tol...