Baghdad (AFP) - More than 230,000 people received a first dose of cholera vaccine in a massive campaign to combat an outbreak of the disease in Iraq, the World Health Organisation said Monday.

Over 2,500 cases of cholera have been confirmed in Iraq since the outbreak began, causing two confirmed deaths, according to the WHO.

The first dose of the vaccine was administered to "91 percent of the targeted 255,000 Syrian refugees and internally displaced Iraqis across 62 refugee and IDP (displaced) camps in 13 governorates," WHO said in a statement.

Another dose must still be administered, with the second round expected to take place in December, it said.

More than 3.2 million Iraqis have been displaced by violence, including the war with the Islamic State jihadist group, since the beginning of 2014, according to the UN.

And over 245,000 Syrians have fled the civil war in their country for Iraq.

Iraqi authorities have blamed the cholera outbreak mostly on the poor quality of water caused by the low level of the Euphrates.

After a short incubation period of two to five days, cholera causes severe diarrhoea, draining the body of fluids.