JOHANNESBURG (AP) — Zambia is set to vaccinate one million people in its capital against cholera as a deadly outbreak grows.

The World Health Organization says doses of the cholera vaccine have been delivered to the impoverished southern African nation as fears spread in Lusaka.

Zambia's health ministry says 58 of the 63 countrywide deaths in the cholera outbreak that began in early October have occurred in the capital. Of the 2,672 cases across the country, 2,558 have been in Lusaka.

Cholera is an acute diarrheal and bacterial infection caused by ingestion of contaminated food or water. Just hours after being infected, vomiting and diarrhea cause severe dehydration that can kill without rapid intervention.