A cholera emergency has been declared in Zimbabwe's capital after 20 people have died, the health minister said on Tuesday.The deaths in Harare have many fearing a repeat of the outbreak that killed thousands at the height of the southern African country's economic problems in 2008. Water and sanitation infrastructure is collapsing.While touring a hospital, Health Minister Obadiah Moyo told reporters this outbreak is spreading to other parts of the country."The numbers are growing by the day and to date there are about over 2 000 cases, that's quite a big number," the minister said, attributing the outbreak to shortages of safe drinking water and poor sanitation. "This whole problem has arisen as a result of blocked sewers. The other problem is that garbage hasn't been collected on a regular basis. There is water problems, no water availability."Residents in some Harare suburbs have gone for months without tap water, forcing them to dig shallow wells and boreholes that have been contaminated by raw sewage flowing from burst pipes.Cholera is caused by ingestion of contaminated food or water and can kill within hours if untreated.The UN children's agency said it is assisting Zimbabwe's government with hygiene and water provisions.Tents have been erected at the Beatrice Road Infectious Diseases Hospital to cater for the growing number of patients.In 2008, over 4 000 people died from cholera, according to government figures.