A cholera outbreak of more than 100,000 cases has erupted in war-ravaged Yemen, killing nearly 800 people, in just over a month, the World Health Organization said Thursday.

The UN health agency said that since the end of April, 101,820 suspected cholera cases had been registered across 19 of the country’s 21 governorates, including 789 deaths.

WHO has warned that a quarter of a million people could fall sick with cholera by the end of the year in Yemen, a country where two-thirds of the population are on the brink of famine.

British charity Oxfam also voiced alarm Thursday at what it described as “a runaway cholera epidemic” in Yemen, pointing out that the disease is currently killing nearly one person every hour.

Cholera is a highly contagious bacterial infection spread through contaminated food or water.

Reining in the disease is particularly complicated in Yemen, where two years of devastating war between Iran-allied Houthis and government forces that backed by a Saudi-led Arab military coalition.

“Yemen is on the edge of an abyss. Lives hang in the balance,” Sajjad Mohammed Sajid, Oxfam’s Yemen country director, said in a statement.

“Cholera is simple to treat and prevent but while the fighting continues the task is made doubly difficult,” he said, insisting that “a massive aid effort is needed now.”