GENEVA: The World Health Organization voiced alarm on Tuesday at the prospect of outbreaks of polio and other diseases in war-ravaged Gaza, amid an already crippling health crisis.

Here is an overview of some of the many health challenges facing the Gaza Strip, according to the UN health agency.

A massive global effort has in recent decades come close to wiping out polio, a crippling and potentially fatal viral disease that mainly affects children under the age of five.

Cases have decreased by 99 percent since 1988, when polio was endemic in 125 countries and 350,000 cases were recorded worldwide.

The wild version of the virus is now only endemic in Afghanistan and Pakistan, but a type of vaccine that contains small amounts of weakened but live polio still causes occasional outbreaks elsewhere.

United Nations agencies said last week that such vaccine-derived type-2 poliovirus had been detected in samples collected from the sewage in Deir al-Balah and Khan Yunis in the Gaza Strip on June 23.

No samples have been taken from humans yet, so it remains unclear if anyone in the Palestinian territory has actually been infected.

Oral polio vaccine (OPV) replicates in the gut and can be passed to others through faecal-contaminated water - meaning it won't hurt the child who has been vaccinated, but could infect their unvaccinated neighbours in places where hygiene and immunisation levels are low.

Ayadil Saparbekov, the WHO's head of health emergencies in the occupied Palestinian territories, said Tuesday that genomic sequencing conducted by the US Centers for Disease Control and Prevention (CDC) in Atlanta indicated that the samples had close genetic linkage with each other and to samples found in Egypt in late 2023.

"We do consider that there is a high risk of spreading of... (the) vaccine-derived polio virus in Gaza," he said.

WHO and the UNICEF children's agency will send a joint team to Gaza on Thursday to begin collecting human samples, with clear recommendations expected within coming days on how to address the threat, including possibly for a mass vaccination campaign.

Israel's military meanwhile said Sunday that it had started vaccinating its troops in Gaza against polio.

Polio is not the only disease that risks spreading in Gaza, which is facing a towering humanitarian crisis after more than nine months of war following Hamas's deadly October 7 attack inside Israel.

"I'm extremely worried about outbreaks happening in Gaza," Saparbekov said, pointing to the "very dire situation with water sanitation."

When it comes to polio and other diseases, he warned "it will be very difficult for the population to follow the advice to wash their hands and drink safe water" when living in shelters with one toilet for 600 people and extremely limited access to clean water.

"With the crippled health system, lack of water and sanitation, as well as lack of access of the population to health services... this is going to be a very bad situation," he warned.

Only 16 of Gaza's 36 hospitals are even partially functional, according to WHO, which on Tuesday lamented "a new mass casualty influx" to the Nasser hospital following deadly Israeli strikes in Khan Yunis.

Saparbekov warned of a dire lack of blood units, medical supplies and hospital beds.

Before the war began there were 3,500 hospital beds available in Gaza. Today there are 1,532, he said, adding that only 45 of Gaza's 105 primary health care facilities were functioning.

At the same time, WHO said as many as 14,000 people are in dire need of being evacuated from Gaza for medical treatment.

Amid such a "crippled health system", Saparbekov warned that Gaza could soon see more people dying of different communicable diseases than from injury-related diseases.

 -AFP