May 21 (UPI) -- A cholera outbreak in war-torn Yemen has killed 315 people since April 27 and is spreading with "unprecedented" speed, the United Nations' World Health Organization said Sunday.
More than 29,300 suspected cases have been reported in 19 of the country's 22 provinces, the agency posted on Twitter. The highest number of likely cases -- more than 6,000 -- are in the capital city, Sana'a, where the Houthi government declared a state of emergency one week ago.
On Friday, the WHO warned that Yemen could have as many as 300,000 cases of cholera within six months and an "extremely high" number of deaths.
"We need to expect something that could go up to 200,000-250,000 cases over the next six months, in addition to the 50,000 cases that have already occurred," Nevio Zagaria, WHO Yemen representative, told reporters in Geneva.
"I have to admit that when I see the data that I saw this morning, not officially released; are really taking us by surprise. The speed of the resurgence of the cholera epidemic is unprecedented," Zagaria said.
About 7.6 million people live in Yemen's cholera-threatened areas, according to U.N. estimates.
Cholera is an acute diarrhoeal infection caused by ingestion of food or water contaminated with the bacterium Vibrio cholera. Almost 75 percent of people infected do not show any symptoms.
The U.S. Centers for Disease Control and Prevention estimates three million to five million cholera cases annually and more than 100,000 deaths occur each year.
Cholera can be treated by immediate replacement of the fluid and salts lost through diarrhea.
But Yemenis are facing a lack of access to food, clean water and medications and more than half of the country's medical facilities are not operating, the WHO said. Burdened medical staff members haven't been paid since September.
Doctors Without Borders, the international medical humanitarian organization, warns that the outbreak is threatening to spiral out of control.
"The fast spread of the current outbreak is extremely alarming," said Ghassan Abou Chaar, the organization's head of mission in Yemen. "Before the outbreak, the health system was already overstretched and people's health needs were already huge. To bring the outbreak under control, it won't be enough simply to treat those people who reach medical facilities. We also need to address the source of the disease, by improving water and sanitation and working in communities to prevent new cases."
The organization has treated 3,092 patients in four cholera treatment centers and nine cholera treatment units. Teams are expecting a delivery of more than 63 tons of supplies in a few days.
The current disease outbreak is a resurgence from an episode last October that peaked in December.
A power struggle has taken place between a Saudi-backed government and Iran-aligned rebels since late 2014.