Cholera has infected tens of thousands in Yemen, and doctors fear the outbreak is starting to get out of control.
The number of suspected cases has doubled in the past five days, according to Doctors Without Borders (MSF).
More than 23,500 people are believed to have fallen sick so far, with the infection spreading across 18 of the poor country's 22 provinces.
"Before the outbreak, the health system was already overstretched and people's health needs were already huge," MSF's Ghassan Abou Chaar said.
Water and sanitation need urgent improvement to hold it back, he said. More than 200 have already died, and around 7.6 million people live in the areas affected.
Yemen has been in civil war for years, with one side backed by Iran and the other, Saudi Arabia, which has just signed a new arms deal with the United States.