The state-run Herald newspaper said that cholera had killed 73 people, including 36 who died just since Friday in the southern border town of Beitbridge, where another 431 have been hospitalised.
"Most of the admissions were on Sunday afternoon, after people had learnt of the outbreak. We expect that number to increase," Beitbridge medical officer Taikaitei Kanongara told the paper.
The disease has spread rapidly due to the breakdown in sanitation in many urban centres, and the outbreak prompted a vow by a group of doctors protesting in Harare on Tuesday to stay away from work it is brought under control.
The non-governmental group Doctors Without Borders (MSF) said it has set up cholera treatment centres in Harare, where 500 patients have been treated so far and an average of 38 new patients are admitted every day.
Most patients come from the Harare suburbs of Budiriro and Glen View, MSF said in a statement, but warned that a total of 1.4 million people in the capital are at risk if the disease keeps spreading.
"Things are getting out of hand" at the Budiriro clinic, said MSF water and sanitation officer Precious Matarutse.
"There are so many patients that the nurses are overwhelmed. In the observation area, one girl died sitting on a bench.
"The staff is utilising each and every available room and still in the observation area patients are lying on the floor," she added.
Another MSF worker Vittorio Varisco warned that clinics were running out of space for the patients.
"It is a constant challenge to keep up with increasing patient numbers," Varisco said.
"Today patients at the Infectious Diseases Hospital are lying outside on the grass and we are setting up tents with additional beds as an overflow for the wards."
Zimbabwe's health system, once among the best in Africa, has collapsed under the weight of the world's highest inflation rate, last estimated in July at 231 million percent.
With one of the world's worst AIDS epidemics, life expectancy in Zimbabwe has fallen to 36 years.
Cholera is endemic in parts of rural Zimbabwe, but had been rare in the cities, where most homes have piped water and flush toilets.
But after years of economic crisis, the nation's infrastructure is breaking down, leaving many people without access to clean water or proper sanitation.
News of the increasing cholera death toll came as about 100 doctors and nurses protested outside Harare's biggest hospital, saying the economic collapse has left them unable to buy medicine or equipment to combat cholera.
Dozens of riot police stopped the doctors from marching in the streets, so they danced barefoot in the hospital parking lot, saying they would not come to work until they have the necessary supplies.
"It is useless for us to come to work, because there are no medicines," said Amon Siveregi, head of the Hospital Doctors Association.
"At times, you just watch an accident victim die, yet you would have been able to save that person if there were medicine and drugs."
"Nothing is functioning," he added.
Doctors' monthly wage of two million Zimbabwe dollars is now worth only about one US dollar, he said.
"It's not even enough to buy lunch, let alone expect us to come to work every day to save people's lives," Siveregi said.