The United Nations has called for “decisive action” to rectify unsafe and unsanitary conditions at the Moria refugee camp on the Greek island of Lesbos, as well as at refugee centers on four other islands, amid rising concerns about disease outbreak in the camps.

The United Nations Refugee Agency (UNHCR) “is urging Greece to intensify efforts to address alarming overcrowding and precarious conditions for asylum seekers and migrants,” a spokesperson said at a press briefing in Geneva on Friday. The UNHCR is calling on the Greek government to implement “emergency measures,” and “expedite its plans to transfer a greater number of asylum-seekers to appropriate accommodation on the mainland.”

Since July 2019, the Moria camp has quadrupled in size and now hosts 18,342 people — in a facility originally built for 2,200. 85% of people living in the camp are refugees; the remainder are classified as migrants. A majority of those living in the camp are families from Afghanistan and Syria, as well as other countries in the Middle East and Africa. A third of the camp’s population is children under the age of 12, according to the UNHCR.

3,545 people have landed on Greece’s shores in the month of January 2020; that number remains on par with the total of 59,000 people whose journey led them to Greece in 2019. Upon their arrival, refugees today are unable to leave the camps due to an EU containment policy which mandates their staying put while their asylum requests are processed. The situation has left Greece’s asylum processing system overstretched, with a current backlog of 90,000 cases — which has resulted in some refugees spending over a year in the camps.

Meanwhile, conditions continue to deteriorate.

Migrants stand near an accumulation of garbage in the stream of the Moria refugee camp on February 5, 2020 in Moria, Greece. Ivan Romano—Getty

While some estimates suggest Greece has received over $1.6 billion in financial aid to help refugees, refugee camps remain dangerous and inadequate. On Lesbos, overcrowding has forced refugees to seek shelter in nearby olive groves. In the winter — when temperatures drop below freezing — refugees are forced to build fires in their thin tents; women and girls are particularly vulnerable to sexual violence. Many women are fearful of using toilets, showers, or getting food in distribution lines, Human Rights Watch reports.

“The situation [for] migrants, including asylum seekers, in the Greek Aegean islands has dramatically worsened over the past 12 months,” the Council of Europe Commissioner for Human Rights, Dunja Mijatović, said in October after visiting reception facilities on three Greek islands. Mijatović noted that there is a drastic lack of medical care and sanitation in the camps, calling it “an explosive situation.”

“I am an experienced doctor, I have seen many patients in my life, but what I saw there had me crying,” Dr. Hana Pospisilova, a volunteer on Lesbos, told The Guardian. “If you read about Spanish flu it was exactly like this that [it] began to spread, in overcrowded facilities where people had a viral infection that became a bacterial infection that killed them,” Pospisilova said.

On Monday, Notis Mitarichi, the Greek Migration Minister announced the government’s plan to set up closed camps for asylum seekers in March. Refugees living in closed camps are allowed to enter and leave the camp during the day, but will be locked in at night. These camps, which are expected to accommodate 20,000 asylum seekers, have been developed in response to increased aggression by locals, and recent outbreaks of violence between refugees, locals and police authorities on the islands. Last week, hundreds of asylum-seekers protested the Moria camp’s deteriorating conditions in Mytilene, the capital of Lesbos. Two riot police squads were dispatched and fired tire gas at protesters.

A migrant falls to the ground while fleeing the demonstration on February 04, 2020 in Mytilene, Greece. Ivan Romano—Getty

As the Moria camp has grown and conditioned have worsened, local residents of the island have also reached their breaking point, leading to a rise in anti-immigrant sentiment.

“The Lesbos community has been abandoned by its own government for almost five years to deal with the consequences of a failed reception system,” Sophie McCann, a Médecins Sans Frontières worker told the Guardian. “Like the refugee community, it is tired.”

The current conservative government, which has held power since mid-2019, has taken a tougher stance on migration. The government passed a law that toughened asylum requirements, increased the number of border patrols, and said it wants to send 200 rejected asylum-seekers back to Turkey every week. In January, the government pledged to build a floating barrier to prevent smuggling boats from landing on Greece’s shores, sparking outcry from rights groups.

“This proposal marks an alarming escalation in the Greek government’s ongoing efforts to make it as difficult as possible for asylum-seekers and refugees to arrive on its shores,” Amnesty International’s Research Director for Europe Massimo Moratti said.

“We are treating patients but nobody is healed,” Pospisilova said. “It’s impossible to heal them in these conditions.”

Get The Brief. Sign up to receive the top stories you need to know right now. Please enter a valid email address. Sign Up Now Check the box if you do not wish to receive promotional offers via email from TIME. You can unsubscribe at any time. By signing up you are agreeing to our Terms of Use and Privacy Policy . This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Thank you! For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters. If you don't get the confirmation within 10 minutes, please check your spam folder.

Contact us at letters@time.com.