Cholera has killed over 3,000 people and infected more than 57,000 Zimbabweans, the World Health Organization said on Wednesday, making it the deadliest outbreak in Africa in 15 years.
The spread of the disease has raised the urgency of forming a new government after rival parties failed to implement a September power-sharing deal seen as a chance to ease a humanitarian crisis.
Regional leaders decided at a summit on Tuesday that a unity government should be formed next month.
Opposition leader Morgan Tsvangirai has said he agrees to form a government with President Robert Mugabe, even though his party voiced disappointment with a deal reached at the summit, a South African newspaper reported on Wednesday.
The contradiction suggested differences had emerged within Tsvangirai's Movement for Democratic Change Over implementation of the September pact. This added to uncertainty over whether a new Zimbabwean leadership would be united enough to tackle an acute economic crisis in which prices are doubling every day.
The MDC has said the outcome of the summit fell "far short of our expectations," raising doubts over prospects for ending the political deadlock.
Mugabe, who has made it clear he would set up a government without the opposition if need be, said talks were concluded and a new cabinet could now be formed.
South Africa's Star newspaper quoted Tsvangirai as saying that resolving outstanding issues over a government was a "work in progress."
"Everyone agrees that — subject to the clearing of all the issues that are outstanding — a coalition government can be formed," he said.
"After all, the whole idea of these negotiations is to form a coalition government, and I therefore agreed to that principle."
The 15-nation Southern African Development Community said after the summit in South Africa — its fifth attempt to secure a deal on forming a unity government — it had agreed that Tsvangirai should be sworn in as prime minister by February 11.
The MDC said in a statement that there are no divisions in the party and its national council will make a decision on an inclusive government on Friday.
The signing of the pact was seen as an opportunity to prevent a total economic collapse that would add to the strain on neighboring countries already hosting millions of Zimbabweans who fled in search of work.
Others are escaping the cholera epidemic.
WHO figures showed an increase of 57 deaths and 1,579 new infections since Tuesday.
The outbreak is one of the only ones in Africa which has hit an entire country, leading to a very high overall case fatality rate of 5.3 percent.
Other big African outbreaks have included one in 1994 in Goma in the former Zaire which hit Rwandan refugees and killed 50,000 people within 3 weeks and a 2006 outbreak which killed over 2,700 people in Angola.
Fears of the cholera spreading in Zimbabwe have stepped up pressure on rival parties to end the political uncertainty.
Zimbabwe's state-run Herald newspaper said MDC Secretary-General Tendai Biti, considered more hardline than Tsvangirai, had made a "sudden U-turn" against implementing the deal.
"There are struggles going on internally, between the pragmatists and the hawks in terms of their contrasting positions on the power-sharing arrangement," said Zimbabwean political analyst Eldred Masunungure.
"This presents a test for Tsvangirai, but I have no doubt that he will prevail over any internal opposition to his decision."