(CNN) A cholera outbreak in war-torn Yemen continues to spread at a rapid pace. Over 124,000 cases have been recorded as of Tuesday, with 923 people -- a quarter of them children -- dead in the current outbreak, the United Nations Children's Fund said in a statement Tuesday.

Cholera is an infection caused by ingestion of Vibrio cholerae bacteria in water or food contaminated with feces. Symptoms include sudden onset of watery diarrhea that can lead to death by severe dehydration. According to the World Health Organization, cholera is widespread in the Middle Eastern nation of Yemen, with the number of cases surging since late April.

"The fact of the matter is, this is really a dire humanitarian situation and seemingly is only getting worse, particularly for children," UNICEF spokesman Christopher Tidey said.

Aid workers say Yemen, which has weathered civil conflict and terrorism for the past two years, is experiencing a humanitarian crisis. Not only are millions of civilians living in the crossfire, but they can no longer afford food, shelter or medicine, as the violence has devastated the economy.

Millions in need of assistance

Of Yemen's population of 27.4 million, UNICEF estimates that 18.8 million are in need of humanitarian assistance, Tidey said. Two-thirds of the population does not have access to safe drinking water or adequate sanitation. Of the country's 12.6 million children, 1.6 million are displaced while nearly 80%, or 9.6 million, require humanitarian assistance, Tidey said.

No age group can avoid cholera. People over 60, for instance, represent 33% of all fatalities from the disease, according to UNICEF. Cholera has an extremely short incubation period of just two hours to five days, and unlike other diarrheal diseases, it can kill even healthy adults within hours, according to the WHO.

While adults in Yemen are suffering, half of all cholera infections there are occurring in children, said Meritxell Relaño, the UNICEF representative in the country.

"Children continue to bear the brunt of the war in Yemen. Many who have become ill or have died from cholera were suffering from malnutrition," Relaño said.

In fact, more than half of the population is food-insecure, according to the CIA's World Factbook

About 2.2 million Yemeni children are malnourished, 462,000 of them severely so and thus currently at risk of death, Tidey said.

"When you have children already in that precarious situation in terms of their own health and well-being and then you have a cholera outbreak on top of that, well, that obviously makes them more vulnerable," he said.

Efforts to help

Countries facing complex emergencies are particularly vulnerable to cholera outbreaks, according to the WHO. That includes Yemen, where the disease has affected about 268 districts in 19 of its 22 governorates, the organization says. Yemen's cholera fatality rate, 0.8%, is nearing what is considered the emergency threshold, 1%.

To stop the spread, the WHO and UNICEF are honing in on the areas reporting the highest number of cases. The WHO has established four cholera treatment facilities and 16 oral dehydration centers in the country. Along with training health workers to manage cases, the WHO is providing emergency medical supplies to treatment facilities.

Dr. Nevio Zagaria, head of the WHO's office in Yemen, said in a statement that the organization has identified hot spots. "Stamp out cholera in these places, and we can slow the spread of the disease and save lives," Zagaria said. "At the same time, we're continuing to support early and proper treatment for the sick and conducting prevention activities across the country."

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UNICEF is involved in providing water and sanitation services and support, including disinfecting water tanks and wells, as well as getting clean water to children.

More than two years of conflict also means damage to societal infrastructure. Medical supplies are flowing into Yemen at a third of the rate of before the conflict began, Tidey said, adding that UNICEF has "95 verified attacks on health facilities, including personnel."

"We know that health and sanitation haven't received their salaries in about nine months," Tidey said. "Nearly half of all the health facilities in the country are not functional. So those two things combined with the ongoing conflict itself makes it very difficult for people who need treatment to access it."