The number of cholera cases in Yemen has hit one million people according to the International Committee of the Red Cross (ICRC), a new milestone for what was already one of the fastest growing outbreaks of the deadly disease in modern history.
After almost three years of war between a Saudi-led coalition and Houthi rebels, more than 80 percent of Yemenis lack access to food, fuel, clean water, and healthcare.
As of late September, cholera had killed more than 2,200 people in Yemen, according to UN figures.
Although cholera has a death rate of 0.3 percent, the size of the outbreak combined with the lack of equipment and medical staff to deal with the crisis puts thousands more at risk of death.
Both the rebels and the coalition are accused of preventing free access to medical facilities, and compounding the crisis by besieging civilian areas or enforcing blockades.
The UN says the outbreak has affected over 90 percent of districts and 21 out of 22 governorates in Yemen.
The disease is spread through water and food that has been contaminated with waste from a person who already has the disease, and occurs most frequently in places with poor sanitation and sewage facilities.
Yemen's conflict has brought its healthcare system to its knees with many hospitals unable to help patients due to a lack of appropriate medicine and damage to equipment caused by Saudi-led coalition air attacks.
Saudi Arabia and a coalition of Arab and Muslim states intervened in Yemen, with western support, in March 2015.
That followed the capture of the Yemeni capital Sanaa in 2014 by Houthi-allied forces, and their subsequent advance southwards towards the port city of Yemen.
Despite control of the country's skies and a naval blockade, Saudi forces have failed to dislodge the Houthis from much of northern Yemen.
The fallout of the continuing conflict on civilians has been massive with millions facing hunger, according to the UN, which says the country is on the brink of famine and described the crisis as the world's worst crisis.