The cholera epidemic in Zimbabwe has so far claimed more than 4,000 lives, with than 89,000 people infected.
A separate outbreak in neighbouring South Africa is being brought under control after 59 people died and more than 12,000 were infected since November.
Most of the cases were in regions near the border with Zimbabwe, but officials said the outbreak in South Africa could not be blamed entirely on Zimbabwe.
SA Health Minister Barbara Hogan told a press briefing that cholera started to develop in South Africa as a consequence of general living conditions and unsafe water supplies.
Millions of Zimbabweans have fled into South Africa and other neighbouring countries since the political crisis began last year.
Meanwhile, Zimbabwan Prime Minister Morgan Tsvangirai has returned to Harare after undergoing medical checks in Botswana following the car crash that killed his wife.
He said he was feeling fine as he left Harare's international airport on his return.
The tragedy comes at a difficult time for Mr Tsvangirai, who faces the daunting task of rescuing the ruined country under a new unity government with President Robert Mugabe.
His Movement for Democratic Change party has said it will conduct its own probe into the accident to see whether foul play was involved.
Mr Tsvangirai, whose face was swollen, was met by officials from the party and government.
Many Zimbabweans are suspicious over the crash, which took place on a potholed highway, one of the country's most dangerous and busiest routes.
The driver of a truck that slammed into Mr Tsvangirai's vehicle was expected to be charged with culpable homicide.