Variant Type 2 Poliovirus Detected in Gaza Sewage Samples
Recent reports have confirmed the presence of circulating vaccine-derived poliovirus (cVDPV) in the Gaza Strip, with the virus isolated from six environmental sewage samples. These samples were collected on June 23, 2024, from two distinct sites located in the Khan Younis and Deir al Balah regions of Gaza.
The genomic sequencing of the isolated poliovirus strains has revealed that they share close genetic links with one another, as well as with a variant of the virus that was previously circulating in Egypt during the latter half of 2023. The last known detection of these related variant polioviruses in Egypt occurred in December 2023. Analysis suggests that the variant could have been introduced to Gaza as early as September 2023.
At this time, it is important to note that while the virus has been identified in environmental samples, there have been no reported cases of paralysis associated with this outbreak.
The Ministry of Health is currently conducting a risk assessment to evaluate the sensitivity of surveillance systems for detecting acute flaccid paralysis (AFP) and to enhance environmental surveillance. Additionally, efforts are underway to assess subnational immunity levels more accurately.
International organizations, including the World Health Organization (WHO), UNICEF, and the United Nations Relief and Works Agency (UNRWA), are collaborating with local public health authorities to address the urgent health needs of the population in Gaza. The ongoing crisis has significantly hampered the ability to maintain comprehensive disease surveillance and immunization services.
Before the outbreak of conflict in October 2023, routine immunization rates in the occupied Palestinian territories (oPt) were at optimal levels. In 2022, polio vaccination coverage (POL3) was reported at an impressive 99%. However, this figure has seen a decline to 89% in 2023, according to the latest WHO-UNICEF routine immunization estimates (WUENIC).
Currently, the healthcare infrastructure in Gaza is severely compromised, with only 16 out of 36 hospitals partially operational and 45 out of 105 primary healthcare facilities functioning. The ongoing conflict has led to significant challenges, including insecurity, inaccessibility, population displacement, and shortages of medical supplies. These factors, combined with deteriorating water quality and weakened sanitation systems, have resulted in decreased routine immunization rates and an elevated risk of vaccine-preventable diseases, including polio.
The WHO has expressed concern regarding the high risk of the spread of this poliovirus strain within Gaza and potentially beyond its borders, particularly in light of the ongoing public health crisis.
As the situation evolves, health authorities and international organizations remain committed to mitigating the impact of this outbreak and ensuring that immunization efforts are restored to safeguard the health of the population in Gaza.
