Kinshasa - The World Health Organization on Saturday sounded the alarm over a cholera outbreak in the Democratic Republic of Congo which has already claimed 528 lives and reached "worrying proportions".The UN says cholera is a major public health problem in the country with millions of cases registered every year. Last year, the disease claimed 817 lives there, according to the WHO."The cholera outbreak in the Democratic Republic of Congo has reached worrying proportions with 20 out of 26 provinces affected by the disease" the UN agency said in a statement.Cholera is transmitted through contaminated drinking water and causes acute diarrhoea, with children facing a particularly high risk of infection.There are between 1.4 and 4.3 million cases of the disease worldwide each year, and as many as 142 000 deaths, according to WHO statistics.As of September 2, Congolese authorities had recorded 24 217 suspected cases, it said. The outbreak has affected several cities and towns in the east, west and north, as well parts of the capital Kinshasa.WHO said the disease could resurface in the sprawling central Grand Kasai region where the infrastructure and sanitary conditions are skeletal. The last cholera outbreak here occurred in 2003.The UN health body said it was donating $400 000 to help deploy technical teams in priority zones and called on Congolese authorities to back efforts to stem the disease by cleaning up mounds of garbage and ensuring the supply of clean drinking water.