With 5000 cases, according to Patrick Cockburn:

The outbreak is among the most serious signs yet that Iraqi health and social services are breaking down as the number of those living in camps and poor housing increases after people flee their homes.

“The disease is spreading very fast,” Dr Juan Abdallah, a senior official in Kurdistan’s health ministry, told a UN agency. “It is the first outbreak of its kind here in the past few decades.”

Doctors in Sulaimaiyah in Iraqi Kurdistan have appealed for help because of the rapidly increasing number of cases, saying there is a shortage of medicines. Although the city has been less affected by fighting than almost anywhere in Iraq, Unicef says that mains water is only available for two hours a day and many people have dug shallow wells outside their homes.

[...] “My two children, husband and mother have been affected by cholera because we weren’t able to get purified water and one of my children is very sick in hospital,” said Um Abir, a 34-year-old mother. “We have been displaced since January and we have to camp near a rubbish tip which, according to the doctor, might be the reason for all of the family being affected.” The number of Iraqi refugees stands at 4.2 million of whom two million have been displaced within Iraq. Many live in huts made out of rubbish and have no fresh water supplies.

In addition to Sulaimamiyah, the cholera has spread to the oil city of Kirkuk.

“The bad sanitation in Iraq, especially in the outskirts of cities where IDPs [internally displaced person] are camped, has put people at serious risk,” said Dr Abdullah. “In Sulaimaniyah and Kirkuk, at least 42 per cent of the population don’t have access to clean water and proper sewage systems.” Unicef says that local reports suggest that only 30 per cent of people in Sulaimaniyah have clean drinking water.

The BBC and al-Jazeera, reporting a day earlier, quote the Kurdish health ministry saying that only 80 cases are confirmed as cholera. The BBC:

An outbreak of cholera in two northern Iraqi provinces has killed eight people and infected 80 others, the Kurdistan Regional Government has said.

Kurdish Health Minister Zeryan Othman said local health authorities were also treating 4,250 suspected cases of the disease in Sulaimaniya and Tamim.

[...] A report by the UK-based charity, Oxfam, and the NGO Co-ordination Committee in Iraq (NCCI) last month warned that 70% of Iraq’s population did not have adequate water supplies and that only 20% had access to effective sanitation.

al-Jazeera quotes WHO:

The World Health Organisation (WHO) said in a statement released on Wednesday that it had established a programme for monitoring cholera in Iraq.

“To date, it is estimated that Sulaimaniya governorate experienced close to 5,000 cases since 10 August, with 10 deaths reported and 51 confirmed cases in Kirkuk,” the statement said.

The statement said that WHO will establish a surveillance system for water quality control, food inspection and case findings and management.

The BBC article said WHO “will establish a system to monitor water quality in the region.” It doesn’t mention WHO’s stats on cholera.

I haven’t found the most recent statement from WHO. Here is one from May 2003. It says that cases of cholera in Iraq have been reported since 1989. So WHO has been reporting on cholera in Iraq since at least 2003.

5000 is a huge number. And these in the North, which has seen least fighting.