It is very likely that polio has infected people in the Gaza Strip, in what would be a setback for global efforts to eradicate the disease, a World Health Organization spokesperson said on Tuesday.
Gaza's health ministry declared a polio epidemic across the Palestinian enclave late on Monday after samples of the virus were found in sewage. It has not announced any human cases.
According to the WHO, polio is now endemic only in Pakistan and Afghanistan, but more than 30 countries are still listed as subject to outbreaks, including Gaza's neighbors Egypt and Israel. Any country risks a return of polio if outbreaks are not contained with mass vaccinations.
The WHO's Christian Lindmeier told a UN press briefing that people had probably already been infected in Gaza but that detecting cases can be difficult since most cases of the potentially deadly viral disease are asymptomatic.
"Having vaccine-derived polio virus in the sewage very likely means that it's out there somewhere in people," he said. "So the risk of (it)... spreading further is there and it would be a setback definitely (for global efforts)."
He said an investigation and risk assessment was underway in Gaza.
Risks of getting polio
Poliomyelitis, which is spread mainly through the faecal-oral route, is a highly infectious virus that can invade the nervous system and cause paralysis and death in young children.
Cases of polio have declined by 99% worldwide since 1988 thanks to mass vaccination campaigns, and efforts continue to eradicate it completely.
The WHO has sent more than 1 million vaccines to prevent children from being infected in Gaza. Israel's military, which is fighting Hamas in Gaza after the terrorist group killed 1,200 people and kidnapped 253 in the October 7 massacre, said last week it would start offering polio shots to its soldiers there.
James Elder, spokesperson for the UN children's agency, said that more than nine months of conflict had led to a drop in polio vaccination rates from 99% to 89%. He voiced concerns about vaccines reaching people in need, given humanitarian access constraints into and within the enclave.
"The mass displacement, the decimation of health infrastructure, the horrendously insecure operating environment, they will make it much, much more difficult (to do vaccinations), hence putting more and more children at risk."
Israel, which vets goods entering Gaza and is in charge of granting security clearance for aid convoys within it, blames UN inefficiency for aid delays.
Gaza's Hamas-run health ministry says over 39,000 people have been killed in Israel's military offensive. Humanitarian workers say the real death toll, including those killed by disease, is likely much higher given high case numbers of Hepatitis A, dysentery, and other diseases among people displaced by the conflict.