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.

Cholera case diagnosed in Oman: health ministry
Muscat (AFP) Nov 9, 2015 - Omani health authorities have urged caution after a woman who had visited Iraq was found to be infected with cholera, local media reported on Monday.

"The Omani woman who was diagnosed with the disease had visited Iraq recently," the local Times of Oman daily quoted the health ministry as saying.

"The patient is receiving treatment in one of the health institutions in the sultanate" and her condition is stable, it added.

"The ministry will continue to pursue precautionary measures for some more time," the ministry said, urging Omanis to ensure they follow strict hygiene guidelines.

Iraqi health authorities launched a major vaccination campaign this month to combat a cholera outbreak that has infected more than 2,200 people, raising fears of a possible spread to neighbouring Gulf countries.

Many Shiites in Oman and other Gulf countries travel for pilgrimage in the holy Iraqi city of Najaf.

Authorities in Iraq 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 its water.

The vaccination campaign in Iraq is focused on people displaced by conflict including the war with the Islamic State group.

The United Nations says the number of people displaced by conflict in Iraq since the start of 2014 has topped 3.2 million.