The United Nations children's fund said it needed 17.5 million dollars (13.6 million euros) to tackle cholera in Zimbabwe.
"Zimbabwe is grappling with a cholera crisis of unprecedented levels," UNICEF said in a press briefing.
"During the past eight weeks the crisis has rapidly deteriorated as the basic service delivery system collapsed. Schools and hospitals are closing, patients cannot access health care, teachers, nurses and doctors are not able to come to work," it said.
The UN estimates that 589 people have died of cholera in Zimbabwe as of December 5 with 13,960 suspected cases declared.
However the world body's chief humanitarian aid body stressed that these figures are based on the number of people reporting to health centres in the poverty-stricken country - and that as many health centres are no longer operational, the actual toll is likely to be higher.
"Three public hospitals in Harare are closed because of a lack of staff. There are no more surgical operations, the obstetrics services and surgery are also shut which means there are silent deaths occurring that we cannot count," said Elisabeth Byrs, spokeswoman for the UN's Office for the Coordination of Humanitarian Affairs (OCHA).
The World Health Organisation said that in a worst-case scenario, up to 60,000 people could become infected - in line with a previous forecast by UNICEF's top official in the country.
"The health-cluster assessment in a worst-case scenario is 60,000 cases," WHO spokeswoman Fadela Chaib told journalists.
UNICEF said it had moved to "full emergency mode" and developed a 120-day emergency response plan focused on relief efforts and the provision of basic social services, for which it would need 17.5 million dollars.