
Israel has also begun offering polio vaccinations to its troops fighting in Gaza after remnants of the virus were found in test samples from the region.
Ayadil Saparbekov, WHO team lead for health emergencies in Gaza and the occupied West Bank, said circulating vaccine-derived poliovirus type 2 had been isolated from environmental samples from sewage.
Comment: Newsweek:
[...] the weakened virus in the OPV vaccine has mutated into a form capable of causing disease. As a result, U.S. health authorities switched to only using the IPV vaccine in 2000 [..]
"There is a high risk of spreading of the circulating vaccine-derived poliovirus in Gaza, not only because of the detection but because of the very dire situation with the water sanitation," he told reporters in Geneva via video link from Jerusalem.
"It may also spill over internationally, at a very high point."
He added that workers from WHO and the UN's children's agency, Unicef, were scheduled to arrive in Gaza on Thursday to collect human stool samples as part of a risk assessment.
Saparbekov said he hoped this would be completed before the end of the week and allow recommendations to be issued, "including the need for a mass vaccination campaign as well as what kind of vaccine should be used and what the age group of the population that will need to be vaccinated".
Epidemic fears
Since Israel began its bombardment of Gaza in October, there have been repeated warnings about the possible outbreak of viral epidemics as a result of the destruction of health, water and sewage infrastructure.
Last week the International Committee of the Red Cross (ICRC) said its hospital and all health facilities in southern Gaza were at "breaking point" and unable to treat those suffering life-threatening wounds.
Comment: Israel has bombed the vast majority of Gaza's hospitals, and it has been intentionally slaughtering healthcare workers; healthcare is near to nonexistent for the majority in Israel's Gaza concentration camp.
The organisation said in a statement that its 60-bed field hospital in Rafah was nearly at capacity following "mass casualty events", including deadly Israeli strikes on al-Mawasi refugee camp, which killed at least 90 Palestinians last week.
The Red Cross said it took in 26 people requiring hospitalisation for shrapnel and other wounds following the attack.
It added that the overwhelming pressure was forcing doctors to make "difficult choices" on who gets treated.
Saparbekov said he was "extremely worried about an outbreak happening in Gaza".
"And this is not only polio, different outbreaks of communicable diseases," he explained.
Israel's military said on Sunday that it was offering "a broad vaccination operation for all ground troops, both regular and reserves".
The army said it was also working with other organisations to take in vaccines for Gaza's Palestinian population, and that 300,000 vaccines had so far been supplied.
Comment: The following alarming reports on the fallout of the use of the polio 'vaccine' elsewhere demonstrate that this may instead create an outbreak: