UNITED NATIONS, July 19 -- Discovering the poliovirus in Gaza environmental samples is deeply concerning but it's a relief that no cases of the paralyzing disease have been reported, UN humanitarians said on Friday.

The UN Office for the Coordination of Humanitarian Affairs (OCHA) is also deeply concerned over the spread of infectious diseases due to severe overcrowding of shelter spaces, dire shortages of clean water and abysmal sanitation and hygiene conditions in Gaza.

"In a particularly worrying development, the World Health Organization (WHO) reports that six environmental samples of variant poliovirus type 2 have been detected in Khan Younis and Deir al Balah," OCHA said. "No paralytic cases have been detected."

The office said polio can cause paralysis and death, especially among unvaccinated children.

WHO head Tedros Adhanom Ghebreyesus said his agency, UNICEF, the UN Relief and Works Agency for Palestine Refugees in the Near East (UNRWA) and the Gaza health ministry are conducting risk assessments to understand the scope of the poliovirus spread and the necessary response, including through prompt vaccination campaigns.

He warned that the decimation of Gaza's health system, shortages of medical supplies, constant displacement of the population, weakened sanitation services, poor water quality, ongoing access obstructions and a lack of security are increasing the risk of vaccine-preventable diseases, including polio.

WHO reported that other infectious diseases in Gaza are surging and that as of July 7, nearly 1 million cases of acute respiratory infections were recorded since the start of the conflict on Oct. 7. Nearly 575,000 cases of acute watery diarrhea and more than 100,000 cases of jaundice were also documented. However, WHO says the actual number of infections is likely far higher.

"About 90 percent of Gaza's population has been displaced at least once since October of last year, with many living in appalling conditions," OCHA said.

Last week, OCHA and humanitarian partners assessed two informal displacement sites and a UNRWA school, and found that most toilets were not working.

"This means sewage is spilling into the streets at some sites," the office said. "The toilets that are available often have doors missing or cannot flush because there is no water to do so. Clean water is extremely scarce, leaving many families to drink highly saline water, which causes stomach pain."

OCHA said that over the past week, aid organizations have seen a surge in displacement from northern to southern Gaza. As of Thursday, humanitarian partners reported more than 2,500 people displaced from northern Gaza to areas farther south in a single week.

The office said humanitarians distribute food, drinking water, hygiene supplies, and some shelter materials to the displaced with efforts for additional assistance to vulnerable groups, including pregnant women, older people, and those with disabilities.

However, OCHA says hostilities continue to pose significant risks to displaced people and humanitarian workers.

  - Xinhua