A cholera outbreak is sweeping through the largest refugee camp in the world.

Doctors Without Borders, a medical charity, reported that seven people have died in Dadaab since the debilitating diarrhoeal disease first hit the Kenyan settlement back on November 23.

In a news release, the doctors said the disease has sickened more than 540 Dadaab residents in all, and doctors built a dedicated treatment center for cholera patients. Doctors said they have seen about 307 in the past three weeks, about 30 percent of whom were children less than 12.

According to the World Health Organization, an arm of the United Nations, cholera is a bacterial disease that can kill within hours if it isn’t treated. The disease is usually transmitted through contaminated food or water, and is fueled by poor hygiene. Refugee camps are particularly at risk for outbreaks because their residents often lack access to clean water and proper sanitation.

Doctors Without Borders reported that funding cuts have accelerated the outbreak, as Dadaab hasn’t received any soap in two months and there aren’t enough latrines for its residents. More than 330,000 refugees live there, according to the United Nations Refugee Agency. The doctors worry seasonal rains could lead to more cases, as the weather has already exacerbated the issue.

“After each heavy rain, we see an increase of patients in our treatment (center),” Charles Gaudry, the head of Doctors Without Borders’ mission in Kenya, said in a statement.

Doctors Without Borders said its staff is working to educate the refugees about cholera and decontaminating the living spaces of infected patients, but called for more long-term solutions and improvements at Dadaab, which is located near Kenya’s eastern border with Somalia.

“The fact that this outbreak has occurred further highlights the dire hygiene and living conditions in the camp and a lack of proper long-term investment in sanitation services,” Gaudry said in a statement.