Disease expert warns polio outbreak in Gaza could spread to Israel
Dr. Lior Nesher says that it is ‘almost impossible’ to stop the spread of the virus in aquifers; unvaccinated children most at risk
Reporter at The Times of Israel
With traces of the poliovirus found in sewage samples in the Gaza Strip last week, the IDF began a campaign to give polio vaccinations or boosters to all soldiers serving there.
No human cases have been reported so far, but there is a concern that the poliovirus might spread throughout the region.
“It will be almost impossible to stop the ecological movement of the virus,” Dr. Lior Nesher, director of the Infectious Disease Institute at Soroka Medical Hospital in Beersheba, told The Times of Israel. “The disease does not respect borders.”
“It is not an emergency now, but it does have the potential to affect people who are not immunized,” Nesher warned.
Most of the soldiers are immunized, Nesher said. The danger, he said, lies elsewhere: When they return from Gaza, they could “carry the disease through mud, through their clothes, through their bowel movements.” Then, the disease could circulate through the country.
Polio is a highly infectious disease, mostly affecting young children, that attacks the nervous system. It can lead to paralysis and in some cases death.
What most concerns Nesher is that for the past few years, there has been a “reduction in vaccine compliance in the Israeli population that may cause a polio outbreak in Israel.”
The virus is primarily spread through fecal-oral contamination, sometimes by drinking contaminated water, poor sanitation, or poor control of sewage.
It can also spread through the underground aquifers, the subterranean areas under Israel which stores groundwater.
In the summer, when it’s dry, those aquifers are not affected. But in a few months, when the rainy season begins and there is flooding, the poliovirus could leak into the Israeli water ecosystem, Nesher said.
If the Israeli water systems become contaminated and there is a reduction in vaccine compliance in the population, then “there will be an outbreak of the virus that will primarily affect unvaccinated children or those who haven’t yet completed their vaccination program.”
Herd immunity needs a herd
Approximately 95% of Israeli children receive the inactivated polio vaccine (IPV) as part of their routine immunization schedule, according to the World Health Organization. The Israeli Health Ministry said that Israel has largely wiped out the disease through an aggressive inoculation campaign. But the disease is not completely eradicated.
“Before the polio vaccine, so many people got polio and suffered from a debilitating illness and even died,” Nesher said. “It’s a safe vaccine. It’s been around for many, many years.”
But “if enough people start to say, I’m not going to vaccinate my kid, I’m going to rely on someone else,” then, Nesher said, Israel “won’t have herd immunity against polio.”
In the case of measles, if the percentage of vaccinated people dips below about 92-93%, then there is a breakout of the disease. There have been upticks in the last few years of both measles and pertussis because the percentage of vaccinated in Israel is below herd immunity levels.
If polio drops, then “we might have an outbreak,” Nesher said.
“I highly recommend that parents who have not vaccinated their children or are delaying their vaccinations should update and continue their vaccination,” he said.
Potential for soldiers to receive a one-time booster
In Israel, the polio vaccination regimen involves four inactivated polio vaccine (IPV) shots given before the age of 18 months and another when the child is in second grade. Babies and toddlers are also given two oral polio vaccine (OPV) doses to provide full protection and prevent the shedding of the virus through the stool into the sewage system. It also prevents young children from infecting others.
The polio vaccine is thought to give lifetime immunity, but in the US, the Centers for Disease Control and Prevention (CDC) recommends that adults who are at increased risk of exposure receive a one-time booster dose of IPV (inactivated polio vaccine) to maintain immunity.
The IDF does not have figures on how many soldiers are not vaccinated at all.
“The IDF is now working in coordination with the Health Ministry to ensure the health of IDF soldiers and the public, and will continue to carry out inspections in the Gaza Strip,” a spokesperson said.
IDF soldiers were also instructed to take preventive actions and maintain personal hygiene.
The heat, accumulating garbage, sewage, and lack of clean water are accelerating the spread of diseases, according to the United Nations Relief and Works Agency for Palestine Refugees (UNRWA). Rising cases of acute hepatitis and various forms of diarrhea have also been reported.
The war started by Hamas’s October 7 massive attack on Israel has led to the destruction of large swaths of Gaza and the internal displacement of the vast majority of its population, resulting in what has been described as a humanitarian crisis for the Palestinians living in ruins and tent camps.
These conditions have led to outbreaks of various diseases, which have also impacted the well-being of the IDF troops fighting there.
Alongside the vaccination campaign for soldiers, the IDF is working with international organizations to bring more vaccines into the Strip for Gazans.
In a statement, the Health Ministry added that Israeli health authorities were “monitoring and evaluating necessary steps to prevent the risk of disease in Israel.”
