UNITED NATIONS (AP) — The United Nations is warning of a possible "third wave" of the cholera epidemic in Yemen, which is already "the largest outbreak on record."

U.N. spokesman Stephane Dujarric said Wednesday there have been more than 1.1 million suspected cases of cholera since April 2017, and the number is increasing. He said over 2,300 deaths have been reported.

Dujarric said humanitarian organizations are trying to avoid a large-scale resurgence and have vaccinated more than 385,000 people in August against the infectious disease in high-risk districts in Hodeida and Ibb governorates.

In May, nearly 275,000 people were vaccinated in Aden in southern Yemen, he said.

Cholera is caused by eating contaminated food or drinking water, and Dujarric said humanitarian organizations are continuing to support water, sanitation, hygiene and health facilities in Yemen.