Why Polio Has Reemerged in Gaza
THIS ARTICLE IS republished from The Conversation under a Creative Commons license.A 10-month-old boy in the Gaza Strip was recently paralyzed by poliovirus—the first such case in the region this century. Israel and Hamas have agreed to a limited ceasefire to allow 640,000 children in the enclave to be vaccinated against the virus. We asked a virologist to explain how the virus emerged in the region after all this time, and how it will be dealt with.The Conversation: Given that polio was all but eradicated in this region of the world, how might the 10-month-old baby in Gaza have caught it?Lee Sherry: The sequences of the polioviruses detected in Gaza in July 2024 suggest that these viruses may be related to a strain circulating in Egypt, with the virus potentially being introduced to Gaza as early as September 2023.This is probably due to the nature of the oral poliovirus vaccine (OPV), which contains a weakened live poliovirus that can be shed by vaccinated people. This suggests the virus may have been introduced by someone traveling to the region.The war in Gaza has also provided an ideal environment for the virus to thrive and spread, due to the unhygienic conditions caused by little access to clean water and sanitation.Can the virus “survive” (remain viable) for long periods without a human host?Yes, poliovirus is an incredibly stable virus that can remain infectious for long periods outside of the human body, depending on the environmental conditions. For example, polioviruses are capable of surviving in groundwater for several weeks.Can you explain what “wild type” poliovirus is, compared with vaccine-derived “variants”?Wild type poliovirus is a virus that is circulating naturally in the environment, whereas vaccine-derived strains are related to the weakened virus present in the OPV, which in extremely rare cases is capable of reverting to a form capable of causing paralysis.Is the wild type still endemic anywhere in the world?Due to the success of the Global Polio Eradication Initiative, led by the World Health Organization, that began in 1988, type 2 and type 3 polioviruses have been declared eradicated. Only type 1 poliovirus is currently circulating in Afghanistan and Pakistan, where there have been 27 recorded cases so far in 2024.A health worker marks the finger of a Palestinian child vaccinated against polio in Deir Al-Balah in the central Gaza Strip. Photograph: NurPhoto/Getty Images
After a quarter of a century, the disease has returned to Gaza, prompting a campaign to immunize all of the territory's children against the virus.
THIS ARTICLE IS republished from The Conversation under a Creative Commons license.
A 10-month-old boy in the Gaza Strip was recently paralyzed by poliovirus—the first such case in the region this century. Israel and Hamas have agreed to a limited ceasefire to allow 640,000 children in the enclave to be vaccinated against the virus. We asked a virologist to explain how the virus emerged in the region after all this time, and how it will be dealt with.
The Conversation: Given that polio was all but eradicated in this region of the world, how might the 10-month-old baby in Gaza have caught it?
Lee Sherry: The sequences of the polioviruses detected in Gaza in July 2024 suggest that these viruses may be related to a strain circulating in Egypt, with the virus potentially being introduced to Gaza as early as September 2023.
This is probably due to the nature of the oral poliovirus vaccine (OPV), which contains a weakened live poliovirus that can be shed by vaccinated people. This suggests the virus may have been introduced by someone traveling to the region.
The war in Gaza has also provided an ideal environment for the virus to thrive and spread, due to the unhygienic conditions caused by little access to clean water and sanitation.
Can the virus “survive” (remain viable) for long periods without a human host?
Yes, poliovirus is an incredibly stable virus that can remain infectious for long periods outside of the human body, depending on the environmental conditions. For example, polioviruses are capable of surviving in groundwater for several weeks.
Can you explain what “wild type” poliovirus is, compared with vaccine-derived “variants”?
Wild type poliovirus is a virus that is circulating naturally in the environment, whereas vaccine-derived strains are related to the weakened virus present in the OPV, which in extremely rare cases is capable of reverting to a form capable of causing paralysis.
Is the wild type still endemic anywhere in the world?
Due to the success of the Global Polio Eradication Initiative, led by the World Health Organization, that began in 1988, type 2 and type 3 polioviruses have been declared eradicated. Only type 1 poliovirus is currently circulating in Afghanistan and Pakistan, where there have been 27 recorded cases so far in 2024.