After noting an explosion of hepatitis A cases in the Gaza Strip, the World Health Organization (WHO) announced in mid-July that it had detected the polio virus in six samples taken in the Palestinian territory. A “very worrying” situation according to epidemiologist Antoine Flahault, professor at the Institute of Global Health in Geneva.
“Worrying” for Gaza first, which is going through a serious health crisis, deprived of a majority of its health structures, water and medicines. “Worrying” for Israel and the global fight against epidemics, then, because epidemics never stop at borders, however monitored they may be. Without international solidarity, nations can do nothing, or almost nothing, against diseases, recalls the specialist.
L’Express: Polio had disappeared from the Palestinian territories since 1999, and seemed on the verge of being eradicated on a global scale. Is there a risk that it will spread again?
Antoine Flahault: So far, no cases of polio have been detected in Gaza, only traces have been found in the water and soil there. It is therefore not possible to say that the disease has made a comeback, in the sense that it does not seem to be circulating among humans, at least from what we know. But the situation is very worrying. So many positive samples pose a high risk of the disease spreading. However, it particularly affects children and can cause irreversible paralysis. This can be fatal in 5 to 10% of cases. Such a resurgence would therefore be dramatic.
The Palestinian territory, completely pounded by the Israeli army since the attacks of October 7 perpetrated by the Hamasdoes he have the means to cope?
Hardly. Israeli bombings have destroyed most of the health infrastructure, from hospitals to water treatment plants. The local population is therefore particularly exposed to health disasters. In addition, while vaccination coverage among the Palestinian population was sufficient to keep the disease at bay in recent years, it must have deteriorated sharply since the start of the war.
In Israelseveral renowned doctors have expressed concern about the disease resurfacing in their own countries. Is this possible?
The virus is detected regularly in Israel. This was the case in 2013, when 87 samples tested positive, in 26 different locations in the south and center of the country. This is also the case in other developed countries, such as in the United States or the United Kingdomwhere the virus was also detected in 2022. Each time, very high vaccination coverage has prevented an epidemic resurgence. But no country is immune for life.
As long as a disease is not completely eradicated, the pressure remains. The Israeli authorities, in their very harsh policy of reprisals against the Palestinian population, thus take the risk of a health boomerang returning to their own population. This is true for polio, whose threat is, in fact, greater since the bombings. It is also true for all the diseases that are already benefiting from the health crisis caused by the war in Gaza.
Polio, like cholera, is transmitted through contact with feces and contaminated water. How could it return to Israel, which has a highly developed water infrastructure?
Both diseases share these transmission characteristics. But if cholera is the disease of unsanitary conditions par excellence, this is less true for poliomyelitis, which is much more resistant in the environment.
So, if we were able to get rid of cholera in developed countries by cleaning up water, it is vaccination that means that today, most countries in the world are free of polio.
Polio is the target of a WHO global eradication program that has been active since the 1980s. On October 11, 2023, Ursula von der Leyen believed she was finally entering the final stretch, and declared: “We are on the verge of eradicating polio from the face of the Earth.” Did she get carried away?
What the President of the European Commission said is still true. We are very close to eradicating polio from the planet, despite a few pockets of very localised resurgences, and significant circulation in two countries, Pakistan and Afghanistan. But when it comes to fighting infectious diseases, nothing is ever a given. Only very high vaccination coverage could eradicate polio viruses from the planet. For the time being, it is not yet sufficient.
These efforts, supported by WHO member states and several philanthropic organizations, such as the Bill and Melinda Gates Foundation, must be commended. They have made it possible to bring quality vaccines to almost all children on the planet, regardless of their resources. Unfortunately, these efforts are too often hampered by armed conflicts and the destruction and displacement they cause. Wars create conditions conducive to the resurgence and spread of infectious diseases, and undermine global efforts. Polio is just one example.
Paradoxically, if vaccines are the solution, they are also partly the problem, and have also contributed to the resurgences observed in recent years…
You are partly right. There are currently two types of vaccines. An injectable one, and an oral one. The first prevents any risk of polio paralysis. The second, cheaper, easier to administer in areas with little health infrastructure, immunizes, but also has the particularity of reducing the carriage of the disease, and therefore the risk that it persists, in the population or in the environment. However, it is made from an attenuated virus, which can continue to live in the bodies of those vaccinated.
In very rare cases, the weakened pathogen manages to mutate, or recombine with other viruses, and becomes virulent again. This can then give rise to the emergence of new strains. The one circulating in Gaza [NDLR : PVDVc2] is itself derived from the vaccine. This was also the case in Indonesia, where similar contaminations were detected. Since 2016, the WHO has been calling for the oral vaccine to no longer be used, to prevent the emergence of these new viruses, but many countries continue to administer this product, because it still protects those who benefit from it.
But the urgent thing is not to prevent the use of these imperfect vaccines. On the contrary, we must ensure that everyone can have a dose, despite the renewed tensions and current crises. The objective, although particularly ambitious, has already been achieved once, against smallpox, which allowed its eradication in 1980. It was also in the euphoria of this victory that the WHO member states then decided to tackle polio. We are almost there. But without great international solidarity, we will not get there.
.