BEIRA, Mozambique (AP) — Mozambican authorities have announced the first cholera death among cyclone survivors in the hard-hit city of Beira as the number of cases rises to 517.

Broadcaster TVM on Sunday night cited national health official Ussene Isse for the new toll.

Cases of the acute diarrheal disease have risen dramatically since the outbreak was declared on Wednesday. Cyclone Idai severely damaged the water system for Beira, a city of 500,000, when it hit on March 14.

The World Health Organization has said some 900,000 cholera vaccine doses are set to arrive on Monday.

Cholera is an acute diarrheal disease that is spread by contaminated water and food. It can kill within hours but is relatively easy to treat.

The overall cyclone death toll in Mozambique is now 518.