(LONDON) — The port city of Mariupol in eastern Ukraine is facing the risk of a cholera epidemic amid the destruction of water supplies and sanitation during the Russian invasion, city officials and health agencies warn.

“The risk of cholera is very high, like red, red level,” Petro Andriushchenko, an advisor to Mariupol’s mayor, told ABC News, adding that the municipality could not provide an estimation of the number of infected cases due to lack of proper access to the occupants amid the occupation by Russian forces.

While the warnings have intensified in the past few days, Mariupol Mayor Vadym Boychenko said on Telegram last month that due to problems with water supply, the city is threatened by an infectious catastrophe and more than 10,000 people may die by the end of the year.

The deteriorating water, sanitation and hygiene infrastructure has set an alarmingly high risk of an outbreak, according to a report in April from the World Health Organization’s Health Cluster Ukraine agency.

The warming spring and summer weather will likely increase transmission, the report said.

“The weather is hot. There are still dead bodies on the streets of the city — especially under the debris of residential buildings. In some blocks, it is impossible to walk by — due to the stench of rotten human flesh. There was no rain for a while, and it is getting hotter,” a resident of Mariupol, who did not want to be named for security concerns, told ABC News.

The condition of hospital staffing is also “catastrophic,” Andriushchenko wrote on his official Telegram channel on Wednesday.

“Visual demonstration of complete paralysis and collapse of medical system… In this state of medicine, any infectious disease turns into a deadly epidemic,” he said.

Andryushchenko told ABC News that swimming has been banned in the sea [of Azov] as a means to control the spread of the disease. Russian occupation authorities were beginning to quarantine the captured city of Mariupol, he said.

Dorit Nitzan, the WHO’s Ukraine incident manager, told reporters last month the international agency’s partners on the ground in Mariupol are observing “actual swamps in the streets.”

Sewage water and drinking water are getting mixed, Nitzan said at a press briefing in Kyiv.

“This is a huge hazard for many infections, including cholera,” she said.

“Accessing Mariupol is an issue, but we are looking for opportunities via partners on the ground,” WHO spokeswoman Margaret Harris told ABC News.

To take necessary measures in controlling the risk of spreading the disease, the international body “has provided Ukraine with guidance on prevention, preparedness, case definitions, detection — including in wastewater monitoring– [and] standards of care and case management,” Harris added.

Due to the lack of water, the city’s residents have drawn untreated water from rivers and lakes, the April report warns, saying Ukraine was also the last European country to declare a cholera epidemic, with 33 cases in Mariupol in 2011.

“There is still no water supply – it is delivered by trucks, and people on the streets are staying in the lines to fill some bottles,” the Mariupol resident who spoke to ABC News said, adding that people in the city have no information about possible affected cases.

Besides facilitating readiness for the use of cholera vaccines in Ukraine, the WHO says it is working with the Ministry of Health to provide risk communication materials advising people on “how to protect themselves, on prevention, but also on treatment, including on what to do at-home.”

The international body has also offered medical supplies, including WHO cholera kits with rapid diagnostic tests (RDTs), Harris said.

The city was reportedly home to over 400,000 people before Russia invaded Ukraine in February. While there are no accurate statistics on the number of current residents, Ukrainian officials estimate that 100,000 to 150,000 people are still living in the occupied city, many in hiding in the basements and bomb shelters.

Harris underlined the critical psychological condition of the people left in the city and how it would contribute to the likely outbreak.

“The fact that people have to be on the move, the fact that they often have close together, that they’re huddling in basements, in bomb shelters, and the incredible trauma, psychological pressure they are under has got to be having a severe effect on their immune systems, weakening their immune system,” she said.

“So even what’s normally just a mild infection for you or me is a much more serious infection in somebody under those conditions,” she added.

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