Evaluation of the bag-mediated filtration system as a novel tool for poliovirus environmental surveillance: Results from a comparative field study in Pakistan.

Nicolette A Zhou ,Jaffer Hussain,Lubna Rehman,Abdirahman Mahamud,Adnan Khurshid,John Scott Meschke,Humayun Asghar,Ghulam Mujtaba,Masroor Alam,Rana Muhammad Safdar ,Nicola K Beck ,G Matrajt ,Syed Sohail Zahoor Zaidi ,Alexandra L Kossik ,Jeffry H Shirai ,Ananda S Bandyopadhyay ,Muhammed Barjes Salman ,Salman Sharif ,David Scott Boyle,Christine S Fagnant-Sperati ,Shahzad Shaukat,Sadaf Khan,Rahim D Agha ,Jamal Ahmed

doi:10.1371/journal.pone.0200551

Abstract

Poliovirus (PV) environmental surveillance (ES) plays an important role in the global eradication program and is crucial for monitoring silent PV circulation especially as clinical cases decrease. This study compared ES results using the novel bag-mediated filtration system (BMFS) with the current two-phase separation method. From February to November 2016, BMFS and two-phase samples were collected concurrently from twelve sites in Pakistan (n = 117). Detection was higher in BMFS than two-phase samples for each Sabin-like (SL) PV serotype (p<0.001) and wild PV type 1 (WPV1) (p = 0.065). Seventeen sampling events were positive for WPV1, with eight discordant in favor of BMFS and two in favor of two-phase. A vaccine-derived PV type 2 was detected in one BMFS sample but not the matched two-phase. After the removal of SL PV type 2 (SL2) from the oral polio vaccine in April 2016, BMFS samples detected SL2 more frequently than two-phase (p = 0.016), with the last detection by either method occurring June 12, 2016. More frequent PV detection in BMFS compared to two-phase samples is likely due to the greater effective volume assayed (1620 mL vs. 150 mL). This study demonstrated that the BMFS achieves enhanced ES for all PV serotypes in an endemic country.

Highlights

Poliovirus (PV) environmental surveillance (ES) is essential to the Global Polio Eradication Initiative’s (GPEI) strategic plan [1,2]
wild PV type 1 (WPV1) was detected in the February bag-mediated filtration system (BMFS) sample from the Sukkur–Makka pumping station site, the BMFS and two-phase samples were not collected concurrently due to logistical supply issues
Of the 16 BMFS samples positive for WPV1, 7 WPV1 isolates were collected from reservoir areas with evidence of indigenous circulation (Karachi, Peshawar, and Quetta; Fig 3), and the remaining 9 were indirectly or directly linked to these high-risk core reservoir areas based on phylogenetic analysis with a homology greater than 95% (S1 Table)

Summary

Objectives

The objective of this study was to compare BMFS ES results with those from sequentially collected, co-located two-phase samples processed by the WHO method [1,15]

Methods

Results

Conclusion