Short communicationField study of fecal excretion as a decision support tool in response to silent reintroduction of wild-type poliovirus 1 into Israel
Section snippets
Background
Israel had been free of wild poliovirus (WPV) since 1988 based on ongoing acute flaccid paralysis (AFP) and environmental surveillance [1]. Routine immunization in Israel has involved inactivated polio vaccine (IPV) only since 2005. In 2013, WPV1 was discovered into Southern Israel [2] and found in sewage samples obtained from Rahat and Beer-Sheva [3]. Molecular analysis determined the strain to be closely related to the South Asia type 1 lineage (WPV1-SOAS) endemic in Afghanistan and Pakistan
Objectives
In the framework of Israel's response to this unprecedented silent reintroduction (WPV1 transmission lacking clinical cases in a population immunized with IPV only), data regarding the force of infection in the community were needed in order to determine the most appropriate supplementary immunization activity (SIA). An urgent field survey of WPV1 excretion was thus carried out.
Study design
The study involved a convenience sample of the population of Southern Israel in July 2013. The primary goal was to estimate the rate of WPV1 excretion and secondary goals were to estimate excretion rates by age group and residence. Our assumption was that children <9 years old, representing birth cohorts not given oral polio vaccine (OPV) were the main source of transmission. Since prevalence was unknown, sampling efforts were concentrated in the Bedouin and Jewish populations at the epicenter
Results
Of 2395 collected samples, 2196 non-duplicate samples were initially analyzed (49% from Bedouin, 51% from Jewish residents). Of 2065 samples with age data, 1576 (76.3%) were obtained from <8 year-olds (OPV-naive), 40 (1.94%) from 8–10 year-olds (transition between vaccine schedules), 122 (5.91%) from 10–22 year-olds (cohorts given OPV and IPV) and 327 (15.84%) from >22 year-olds (cohorts given OPV only).
Sixty-one subjects excreted WPV1-SOAS (2.77%), of whom 55 were Bedouin (90.16%). Among 59
Discussion
The detection of silent introduction of WPV1 into Israel via environmental surveillance created challenges for risk assessment (magnitude of virus circulation and correlation between environmental findings and human excretion), risk management (data needed to support the decision-making regarding a vaccination campaign and target population), and risk communication (generate evidence to facilitate acceptance of a live vaccine campaign) [10]. The development of a novel molecular assay specific
Funding
None.
Conflicts of interest
None.
Ethical approval
The study was approved by the Institutional Review Board of Sheba Medical Center (SMC-0774-13) and the CDC.
Authors’ contribution
All authors have contributed to this work and qualify for authorship.
Acknowledgements
The authors would like to thank the following: Southern District Health Office personnel for collection of specimens and data; The clinical laboratory services of three Israeli HMO's: South District laboratories of Clalit Health Services (D Amichay, E. Fuchs and staff), Central laboratories of Maccabbi Health Services (B. Sheinberg, M. Parizade, D.Taran and staff) and Leumit Health Services (Y. Dickstein, N. Ben Horin and staff); Laboratory personnel at the Central Virology Laboratory, Israel
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